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<channel>
	<title>비선형운동방정식 &#8211; MyEngNote</title>
	<atom:link href="https://myengnote.com/tag/%EB%B9%84%EC%84%A0%ED%98%95%EC%9A%B4%EB%8F%99%EB%B0%A9%EC%A0%95%EC%8B%9D/feed/" rel="self" type="application/rss+xml" />
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	<description></description>
	<lastBuildDate>Wed, 08 Jul 2026 04:42:43 +0000</lastBuildDate>
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		<title>단진자 주기 계산기 &#038; 시뮬레이터</title>
		<link>https://myengnote.com/pendulum-dynamics-calculator-simulator/</link>
					<comments>https://myengnote.com/pendulum-dynamics-calculator-simulator/#respond</comments>
		
		<dc:creator><![CDATA[동동]]></dc:creator>
		<pubDate>Tue, 02 Jun 2026 09:48:16 +0000</pubDate>
				<category><![CDATA[공학계산기]]></category>
		<category><![CDATA[단진동진자]]></category>
		<category><![CDATA[비선형운동방정식]]></category>
		<category><![CDATA[에너지보존]]></category>
		<category><![CDATA[장력계산]]></category>
		<category><![CDATA[주기계산]]></category>
		<guid isPermaLink="false">https://myengnote.com/pendulum-dynamics-calculator-simulator/</guid>

					<description><![CDATA[진자의 길이, 추의 질량, 초기 요동 각도 및 공기 감쇠계수를 설정하여 실시간 비선형 운동궤적을 추적하고, 동적 장력과 위치/운동 에너지 보존 거동을 분석하는 물리 시뮬레이터입니다.]]></description>
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<h2 style="font-size: 1.6em; font-weight: 800; color: #0c0e25; border-bottom: 2px solid #00f2fe; padding-bottom: 8px; margin-bottom: 20px;"><img src="https://s.w.org/images/core/emoji/17.0.2/72x72/1f680.png" alt="🚀" class="wp-smiley" style="height: 1em; max-height: 1em;" /> 단진자 주기 계산기 &#038; 시뮬레이터</h2>


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.pendulum-calculator-wrapper .app-main-grid,
.pendulum-calculator-wrapper .main-grid,
.pendulum-calculator-wrapper .sim-grid {
    display: grid !important;
    grid-template-columns: 340px 1fr !important;
    gap: 24px !important;
    align-items: start !important;
}
/* 3열 레이아웃을 2열 레이아웃으로 변경하는 특화 스타일 */
.pendulum-calculator-wrapper .right-column {
    display: flex !important;
    flex-direction: column !important;
    gap: 24px !important;
    min-width: 0 !important;
    grid-column: 2 !important;
}
.pendulum-calculator-wrapper .simulation-panel,
.pendulum-calculator-wrapper .canvas-panel,
.pendulum-calculator-wrapper .sim-panel {
    grid-column: auto !important;
    order: 1 !important;
    align-self: stretch !important;
}
.pendulum-calculator-wrapper .control-panel {
    grid-column: 1 !important;
}
/* 2열 통합 결과 분석 영역 레이아웃 */
.pendulum-calculator-wrapper .simulation-results-section {
    display: grid !important;
    grid-template-columns: 1.1fr 1.3fr !important;
    gap: 20px !important;
    border-top: 1px solid var(--color-border) !important;
    padding-top: 20px !important;
    margin-top: 10px !important;
    align-items: stretch !important;
}
/* Readout Box 스타일 */
.pendulum-calculator-wrapper .simulation-results-section .ratio-readout-box,
.pendulum-calculator-wrapper .simulation-results-section .re-readout-box,
.pendulum-calculator-wrapper .simulation-results-section .status-readout-box,
.pendulum-calculator-wrapper .simulation-results-section .gauge-container {
    grid-column: 1 !important;
    grid-row: 1 !important;
    margin: 0 !important;
    height: auto !important;
    display: flex !important;
    flex-direction: column !important;
    justify-content: center !important;
}
.pendulum-calculator-wrapper .simulation-results-section .results-grid {
    grid-column: 2 !important;
    grid-row: 1 / span 2 !important;
    display: flex !important;
    flex-direction: column !important;
    gap: 12px !important;
    justify-content: flex-start !important;
}
.pendulum-calculator-wrapper .simulation-results-section .results-grid .result-card {
    flex: none !important;
    display: flex !important;
    align-items: center !important;
    min-height: 72px !important;
    height: auto !important;
    padding: 12px 16px !important;
}
.pendulum-calculator-wrapper .simulation-results-section .formula-card {
    grid-column: 1 !important;
    grid-row: 2 !important;
}
/* 모바일/반응형 (800px 이하) ── 항상 세로형(1열) 정렬 및 시뮬레이터 캔버스 최상단 배치 */
@media (max-width: 800px) {
    .pendulum-calculator-wrapper .app-main-grid,
    .pendulum-calculator-wrapper .main-grid,
    .pendulum-calculator-wrapper .sim-grid {
        grid-template-columns: 1fr !important;
        display: flex !important;
        flex-direction: column !important;
    }
    .pendulum-calculator-wrapper .control-panel {
        order: 2 !important;
        width: 100% !important;
    }
    .pendulum-calculator-wrapper .right-column {
        order: 1 !important;
        width: 100% !important;
        display: flex !important;
        flex-direction: column !important;
    }
    .pendulum-calculator-wrapper .simulation-panel,
    .pendulum-calculator-wrapper .canvas-panel,
    .pendulum-calculator-wrapper .sim-panel,
    .pendulum-calculator-wrapper .canvas-section {
        order: -1 !important;
    }
    .pendulum-calculator-wrapper .simulation-results-section {
        grid-template-columns: 1fr !important;
    }
    .pendulum-calculator-wrapper .simulation-results-section .ratio-readout-box,
    .pendulum-calculator-wrapper .simulation-results-section .re-readout-box,
    .pendulum-calculator-wrapper .simulation-results-section .status-readout-box,
    .pendulum-calculator-wrapper .simulation-results-section .gauge-container {
        grid-column: 1 !important;
        grid-row: auto !important;
        height: auto !important;
    }
    .pendulum-calculator-wrapper .simulation-results-section .results-grid {
        grid-column: 1 !important;
        grid-row: auto !important;
    }
    .pendulum-calculator-wrapper .simulation-results-section .formula-card {
        grid-column: 1 !important;
        grid-row: auto !important;
    }
}
.pendulum-calculator-wrapper .app-container,
.pendulum-calculator-wrapper .main-container {
    max-width: 100% !important;
    padding: 12px !important;
}
/* Premium Advice/Formula Card & Typography Overrides */
.pendulum-calculator-wrapper .simulation-results-section .formula-card,
.pendulum-calculator-wrapper .results-panel .formula-card {
    background: #ffffff !important;
    border: 1px solid var(--color-border) !important;
    border-radius: 12px !important;
    padding: 16px !important;
    box-shadow: var(--shadow-card) !important;
    transition: all 0.2s ease !important;
    display: flex !important;
    flex-direction: column !important;
    gap: 8px !important;
}
.pendulum-calculator-wrapper .simulation-results-section .formula-card h4,
.pendulum-calculator-wrapper .results-panel .formula-card h4 {
    font-weight: 700 !important;
    color: var(--color-text-main) !important;
}
.pendulum-calculator-wrapper #text-judgment {
    font-size: 12px !important;
    font-weight: 500 !important;
    color: var(--color-text-muted) !important;
    line-height: 1.6 !important;
    word-break: keep-all !important;
}
</style>
<div class="pendulum-calculator-wrapper" style="position: relative; width: 100%; box-sizing: border-box; overflow: hidden; margin: 30px auto; border-radius: 20px;">
    <div class="app-background-glow" style="position: absolute; top: 0; left: 0; width: 100%; height: 100%; z-index: 1; pointer-events: none; overflow: hidden;"></div>
    <div style="position: relative; z-index: 2; width: 100%;">
    <div class="app-container">
        <!-- Header -->
        <header class="app-header">
            <div class="logo-area">
                <div class="logo-icon"><i class="fa-solid fa-bezier-curve fa-spin-slow text-cyan"></i></div>
                <div>
                    <h1>PENDULUM DYNAMICS</h1>
                    <div class="subtitle">단진동 현수 진자 주기 계산 &#038; 비선형 시뮬레이터</div>
                </div>
            </div>
            <div class="header-badge">
                <div class="pulse-dot"></div>
                <div class="badge-text">SHM PHYSICS CALCULATOR ACTIVE</div>
            </div>
        </header>
        <!-- Main Layout Grid -->
        <main class="app-main-grid">
            <!-- Left Panel: Controls -->
            <section class="panel control-panel">
                <div class="panel-header">
                    <i class="fa-solid fa-sliders text-cyan"></i>
                    <h2>스윙 설계 요소</h2>
                </div>
                <!-- Rod Length (L) -->
                <div class="input-group">
                    <div class="input-label-row">
                        <label><i class="fa-solid fa-arrows-left-right text-cyan"></i> 진자 현수 길이 (L)</label>
                        <span class="helper-text">(0.5 ~ 4.0 m)</span>
                    </div>
                    <div class="number-input-wrapper">
                        <input type="number" id="input-length" class="custom-number-input" min="0.5" max="4.0" step="0.1" value="1.5">
                        <div class="unit-badge">m</div>
                    </div>
                    <input type="range" id="slider-length" class="custom-slider" min="5" max="40" step="1" value="15">
                </div>
                <!-- Bob Mass (m) -->
                <div class="input-group">
                    <div class="input-label-row">
                        <label><i class="fa-solid fa-weight-hanging text-magenta"></i> 흔들림 추 질량 (M)</label>
                        <span class="helper-text">(0.1 ~ 5.0 kg)</span>
                    </div>
                    <div class="number-input-wrapper">
                        <input type="number" id="input-mass" class="custom-number-input" min="0.1" max="5.0" step="0.1" value="1.0">
                        <div class="unit-badge">kg</div>
                    </div>
                    <input type="range" id="slider-mass" class="custom-slider" min="1" max="50" step="1" value="10">
                </div>
                <!-- Initial Angle (theta0) -->
                <div class="input-group">
                    <div class="input-label-row">
                        <label><i class="fa-solid fa-compass text-purple"></i> 초기 스윙 낙하 각도 (θ₀)</label>
                        <span class="helper-text">(-75 ~ 75 deg)</span>
                    </div>
                    <div class="number-input-wrapper">
                        <input type="number" id="input-ang" class="custom-number-input" min="-75" max="75" value="45">
                        <div class="unit-badge">deg</div>
                    </div>
                    <input type="range" id="slider-ang" class="custom-slider" min="-75" max="75" step="1" value="45">
                </div>
                <!-- Gravity Fields -->
                <div class="input-group">
                    <div class="input-label-row">
                        <label><i class="fa-solid fa-globe"></i> 우주 천체 중력장 (g)</label>
                    </div>
                    <div class="segmented-control" id="control-gravity">
                        <button class="segment-btn active" data-value="9.81">지구 (9.8)</button>
                        <button class="segment-btn" data-value="24.79">목성 (24.8)</button>
                        <button class="segment-btn" data-value="1.62">달 (1.6)</button>
                    </div>
                </div>
                <!-- Damping Coefficient b -->
                <div class="input-group">
                    <div class="input-label-row">
                        <label><i class="fa-solid fa-wind"></i> 공기 스윙 마찰 감쇠 계수 (b)</label>
                        <span class="helper-text">(0.00 ~ 0.40)</span>
                    </div>
                    <div class="number-input-wrapper">
                        <input type="number" id="input-damping" class="custom-number-input" min="0.00" max="0.40" step="0.01" value="0.02">
                        <div class="unit-badge">b</div>
                    </div>
                </div>
                <!-- Action actions -->
                <div class="control-actions">
                    <button id="btn-toggle" class="action-btn primary-btn"><i class="fa-solid fa-play"></i> 시뮬레이션 일시정지</button>
                    <button id="btn-reset" class="action-btn"><i class="fa-solid fa-rotate-left"></i> 초기 각도 정렬</button>
                </div>
                <!-- Presets -->
                <div class="presets-section">
                    <h3><i class="fa-solid fa-tags text-cyan"></i> 물리 흔들림 프리셋</h3>
                    <div class="presets-grid">
                        <button class="preset-btn" data-preset="grandfather">
                            <div class="preset-icon"><i class="fa-solid fa-clock"></i></div>
                            <div class="preset-details"><span class="preset-name">괘종 시계 진자<br><span style="font-size: 10.5px; color: var(--color-text-muted); font-weight: 500;">(L=1.0m, m=1.5kg, θ=25°, 지구)</span></div>
                        </button>
                        <button class="preset-btn" data-preset="lunar">
                            <div class="preset-icon"><i class="fa-solid fa-moon"></i></div>
                            <div class="preset-name">달 저중력 무감쇠 진동<br><span style="font-size: 10.5px; color: var(--color-text-muted); font-weight: 500;">(L=2.0m, θ=45°, 달, b=0)</span></div>
                        </button>
                        <button class="preset-btn" data-preset="viscous">
                            <div class="preset-icon"><i class="fa-solid fa-oil-can"></i></div>
                            <div class="preset-name">점성 매질 억제 스윙<br><span style="font-size: 10.5px; color: var(--color-text-muted); font-weight: 500;">(L=1.2m, m=3kg, θ=70°, b=0.3)</span></div>
                        </button>
                    </div>
                </div>
            </section>
            <!-- Auto Injected Right Column wrapper for Design 1 -->
            <div class="right-column">
                <section class="panel simulation-panel">
                                <div class="panel-header">
                                    <div style="display: flex; align-items: center; gap: 12px;">
                                        <i class="fa-solid fa-circle-nodes text-cyan"></i>
                                        <h2>실시간 진동 거동 &#038; 위치/운동 에너지 보존</h2>
                                    </div>
                                    <div id="txt-swing-state" class="canvas-scale-indicator text-cyan">진동 구동 중</div>
                                </div>
                                <div class="canvas-wrapper">
                                    <canvas id="physics-canvas"></canvas>
                                </div>
                                <!-- Mini Metrics -->
                                <div class="simulation-metrics-strip">
                                    <div class="mini-metric">
                                        <div class="label">실시간 스윙 각속도</div>
                                        <div id="txt-live-omega" class="value">0.00 rad/s</div>
                                    </div>
                                    <div class="mini-divider"></div>
                                    <div class="mini-metric">
                                        <div class="label">실시간 구동 선속도</div>
                                        <div id="txt-live-speed" class="value">0.00 m/s</div>
                                    </div>
                                </div>
                                <!-- Integrated Results Analysis Section -->
                            <div class="simulation-results-section">
                                <div class="ratio-readout-box">
                                    <div class="ratio-title">최저점 동적 최대 인장 장력</span><span class="preset-spec">F_T</span></div>
                                    <div id="txt-peak-tension" class="ratio-value">14.8 N</div>
                                    <div id="txt-static-weight" class="ratio-type">(정하중 정지 중력: 9.8 N)</div>
                                </div>
                                <div class="results-grid">
                                        <div class="result-card">
                                        <div class="card-icon"><i class="fa-solid fa-stopwatch text-cyan"></i></div>
                                        <div class="card-content">
                                            <span class="card-unit">단순 조화 주기 (T₀)</span>
                                            <span id="txt-period-out" class="card-value">2.46 sec</span>
                                        </div>
                                    </div>
                                        <div class="result-card">
                                        <div class="card-icon"><i class="fa-solid fa-wave-square text-magenta"></i></div>
                                        <div class="card-content">
                                            <span class="card-unit">진동계 고유 고유진동수 (ω₀)</span>
                                            <span id="txt-omega-out" class="card-value">2.56 rad/s</span>
                                        </div>
                                    </div>
                                        <div class="result-card">
                                        <div class="card-icon"><i class="fa-solid fa-bolt text-purple"></i></div>
                                        <div class="card-content">
                                            <span class="card-unit">낙하점 최대 저장 위치에너지 (PE)</span>
                                            <span id="txt-pe-out" class="card-value">4.31 Joules</span>
                                        </div>
                                    </div>
                                    </div>
                                <div class="formula-card"
                                    <h4>현수 비선형 복원 공식</h4>
                                    <div class="formula-equation">T = 2π &radic;(L / g) [sec]</div>
                                    <div class="formula-equation">F_T = M·g·cosθ + M·L·ω² [N]</div>
                                </div>
                            </div>
                </section>
            </div>
            <!-- Right Panel: Quantitative Results -->
        </main>
        <!-- Disclaimer Footer -->
        <footer class="app-disclaimer" style="margin-top: 20px; padding: 12px 16px; background: rgba(0, 0, 0, 0.015); border: 1px solid var(--color-border); border-radius: 12px; font-size: 11px; color: var(--color-text-muted); line-height: 1.5; text-align: left; display: flex; gap: 10px; align-items: flex-start; clear: both;">
            <i class="fa-solid fa-circle-info" style="color: var(--color-cyan); font-size: 14px; margin-top: 2px; flex-shrink: 0;"></i>
            <span><strong>면책 조항 (Disclaimer):</strong> 본 시뮬레이터의 계산 결과는 교육 및 참고용으로만 제공되며, 실제 제품 설계나 제작 시에는 반드시 최신 공학 규격 및 공식 표준 설계 기준을 재확인하시기 바랍니다. 계산 값의 무결성을 보장하지 않으며, 이로 인해 발생하는 직접적/간접적 손해에 대해 제작자 및 본 블로그는 어떠한 책임을 지지 않습니다.</span>
        </footer>
</div>
    <!-- JavaScript Circuit Simulation Engine -->
    </div>
</div>
<script>
        (function() {
        let isInit = false;
        function initSimulator() {
            if (isInit) return;
            const canvas = document.getElementById('physics-canvas');
            if (!canvas) return;
            const ctx = canvas.getContext('2d');
            if (!ctx) return;
            isInit = true;
            window.__pendulum_initialized = true;
            // DOM Elements
            const sliderLength = document.getElementById('slider-length');
            const inputLength = document.getElementById('input-length');
            const sliderMass = document.getElementById('slider-mass');
            const inputMass = document.getElementById('input-mass');
            const sliderAng = document.getElementById('slider-ang');
            const inputAng = document.getElementById('input-ang');
            const inputDamping = document.getElementById('input-damping');
            const btnToggle = document.getElementById('btn-toggle');
            const btnReset = document.getElementById('btn-reset');
            const presetButtons = document.querySelectorAll('.preset-btn');
            const controlGravity = document.getElementById('control-gravity');
            const txtPeakTension = document.getElementById('txt-peak-tension');
            const txtStaticWeight = document.getElementById('txt-static-weight');
            const txtPeriodOut = document.getElementById('txt-period-out');
            const txtOmegaOut = document.getElementById('txt-omega-out');
            const txtPeOut = document.getElementById('txt-pe-out');
            const txtSwingState = document.getElementById('txt-swing-state');
            const txtLiveOmega = document.getElementById('txt-live-omega');
            const txtLiveSpeed = document.getElementById('txt-live-speed');
            // State variables
            const state = {
                length: 1.5, // m
                mass: 1.0, // kg
                ang0: 45.0, // deg (initial)
                gravity: 9.81, // m/s2
                damping: 0.02,
                // Swing Dynamic states
                theta: (45.0 * Math.PI) / 180.0, // radians
                omega: 0.0, // angular velocity rad/s
                isRunning: true,
                swingPathHistory: [],
                lastTime: 0
            };
            function resizeCanvas() {
                const rect = canvas.getBoundingClientRect();
                const dpr = window.devicePixelRatio || 1;
                canvas.width = rect.width * dpr;
                canvas.height = rect.height * dpr;
                ctx.scale(dpr, dpr);
            }
            resizeCanvas();
            window.addEventListener('resize', resizeCanvas);
            setTimeout(resizeCanvas, 300);
            // Sync Inputs
            function syncLengthFromSlider() {
                const val = parseFloat(sliderLength.value) / 10.0;
                inputLength.value = val.toFixed(1);
                state.length = val;
                clearPresets();
                updateCalculations();
                resetStateToInitial();
            }
            function syncLengthFromInput() {
                let val = parseFloat(inputLength.value);
                if (isNaN(val)) { val = 0.5; }
                if (val < 0.5) { val = 0.5; }
                if (val > 4.0) { val = 4.0; }
                sliderLength.value = Math.round(val * 10);
                state.length = val;
                clearPresets();
                updateCalculations();
                resetStateToInitial();
            }
            function syncMassFromSlider() {
                const val = parseFloat(sliderMass.value) / 10.0;
                inputMass.value = val.toFixed(1);
                state.mass = val;
                clearPresets();
                updateCalculations();
            }
            function syncMassFromInput() {
                let val = parseFloat(inputMass.value);
                if (isNaN(val)) { val = 0.1; }
                if (val < 0.1) { val = 0.1; }
                if (val > 5.0) { val = 5.0; }
                sliderMass.value = Math.round(val * 10);
                state.mass = val;
                clearPresets();
                updateCalculations();
            }
            function syncAngFromSlider() {
                const val = parseInt(sliderAng.value);
                inputAng.value = val;
                state.ang0 = val;
                clearPresets();
                updateCalculations();
                resetStateToInitial();
            }
            function syncAngFromInput() {
                let val = parseInt(inputAng.value);
                if (isNaN(val)) { val = 0; }
                if (val < -75) { val = -75; }
                if (val > 75) { val = 75; }
                sliderAng.value = val;
                state.ang0 = val;
                clearPresets();
                updateCalculations();
                resetStateToInitial();
            }
            function resetStateToInitial() {
                state.theta = (state.ang0 * Math.PI) / 180.0;
                state.omega = 0.0;
                state.swingPathHistory = [];
            }
            // Simple Pendulum Mechanics Sizing
            function updateCalculations() {
                // T0 = 2 * pi * sqrt(L / g)
                const t0 = 2.0 * Math.PI * Math.sqrt(state.length / state.gravity);
                // ω0 = sqrt(g / L)
                const omega0 = Math.sqrt(state.gravity / state.length);
                // Max Initial PE = m * g * L * (1 - cos(theta0))
                const rad0 = (state.ang0 * Math.PI) / 180.0;
                const peInit = state.mass * state.gravity * state.length * (1.0 - Math.cos(rad0));
                // Peak dynamic velocity at BDC: v_max = sqrt(2 * g * L * (1 - cos(theta0)))
                const vMax = Math.sqrt(2.0 * state.gravity * state.length * (1.0 - Math.cos(rad0)));
                const omegaMax = vMax / state.length;
                // Max dynamic tension: F_T_max = m*g + m*L*omegaMax^2 = m*g * (3 - 2*cos(theta0))
                const fTMax = state.mass * state.gravity * (3.0 - 2.0 * Math.cos(rad0));
                const staticWeight = state.mass * state.gravity;
                txtPeriodOut.innerText = t0.toFixed(2) + ' sec';
                txtOmegaOut.innerText = omega0.toFixed(2) + ' rad/s';
                txtPeOut.innerText = peInit.toFixed(2) + ' J';
                txtPeakTension.innerText = fTMax.toFixed(1) + ' N';
                txtStaticWeight.innerText = '(정하중 정지 중력: ' + staticWeight.toFixed(1) + ' N)';
            }
            // Presets
            function loadPreset(key) {
                clearPresets();
                presetButtons.forEach(btn => {
                    if (btn.dataset.preset === key) {
                        btn.classList.add('active');
                    }
                });
                if (key === 'grandfather') {
                    state.length = 1.0;
                    state.mass = 1.5;
                    state.ang0 = 25;
                    state.gravity = 9.81;
                    state.damping = 0.01;
                }
                if (key === 'lunar') {
                    state.length = 2.0;
                    state.mass = 1.0;
                    state.ang0 = 45;
                    state.gravity = 1.62;
                    state.damping = 0.00;
                }
                if (key === 'viscous') {
                    state.length = 1.2;
                    state.mass = 3.0;
                    state.ang0 = 70;
                    state.gravity = 9.81;
                    state.damping = 0.30;
                }
                // Sync elements
                inputLength.value = state.length.toFixed(1);
                sliderLength.value = Math.round(state.length * 10);
                inputMass.value = state.mass.toFixed(1);
                sliderMass.value = Math.round(state.mass * 10);
                inputAng.value = state.ang0;
                sliderAng.value = state.ang0;
                inputDamping.value = state.damping.toFixed(2);
                document.querySelectorAll('#control-gravity .segment-btn').forEach(btn => {
                    btn.classList.remove('active');
                    if (parseFloat(btn.dataset.value) === state.gravity) {
                        btn.classList.add('active');
                    }
                });
                resetStateToInitial();
                updateCalculations();
            }
            function clearPresets() {
                presetButtons.forEach(btn => btn.classList.remove('active'));
            }
            // Bind Events
            sliderLength.addEventListener('input', syncLengthFromSlider);
            inputLength.addEventListener('change', syncLengthFromInput);
            sliderMass.addEventListener('input', syncMassFromSlider);
            inputMass.addEventListener('change', syncMassFromInput);
            sliderAng.addEventListener('input', syncAngFromSlider);
            inputAng.addEventListener('change', syncAngFromInput);
            inputDamping.addEventListener('change', () => {
                let val = parseFloat(inputDamping.value);
                if (isNaN(val)) { val = 0.00; }
                if (val < 0.00) { val = 0.00; }
                if (val > 0.40) { val = 0.40; }
                inputDamping.value = val.toFixed(2);
                state.damping = val;
                clearPresets();
                updateCalculations();
            });
            // Gravity field selector
            document.querySelectorAll('#control-gravity .segment-btn').forEach(btn => {
                btn.addEventListener('click', () => {
                    document.querySelectorAll('#control-gravity .segment-btn').forEach(b => b.classList.remove('active'));
                    btn.classList.add('active');
                    state.gravity = parseFloat(btn.dataset.value);
                    clearPresets();
                    updateCalculations();
                    resetStateToInitial();
                });
            });
            btnToggle.addEventListener('click', () => {
                state.isRunning = !state.isRunning;
                if (state.isRunning) {
                    btnToggle.innerHTML = '<i class="fa-solid fa-pause"></i> 시뮬레이션 일시정지';
                    txtSwingState.innerText = "진동 구동 중";
                    txtSwingState.style.color = "var(--color-cyan)";
                } else {
                    btnToggle.innerHTML = '<i class="fa-solid fa-play"></i> 시뮬레이션 재개';
                    txtSwingState.innerText = "일시 정지됨";
                    txtSwingState.style.color = "var(--color-warning)";
                }
            });
            btnReset.addEventListener('click', () => {
                resetStateToInitial();
                txtSwingState.innerText = "진자 초기 정렬";
                txtSwingState.style.color = "var(--color-cyan)";
            });
            presetButtons.forEach(btn => {
                btn.addEventListener('click', () => {
                    loadPreset(btn.dataset.preset);
                });
            });
            // Animation Loop
            function animate(currentTime) {
                requestAnimationFrame(animate);
                let dt = (currentTime - state.lastTime) / 1000;
                if (isNaN(dt)) { dt = 0.016; }
                if (dt < 0) { dt = 0.016; }
                if (dt > 1.0) { dt = 0.016; }
                state.lastTime = currentTime;
                const width = canvas.width / (window.devicePixelRatio || 1);
                const height = canvas.height / (window.devicePixelRatio || 1);
                ctx.clearRect(0, 0, width, height);
                // Draw blueprint grid
                ctx.save();
                ctx.strokeStyle = 'rgba(2, 132, 199, 0.06)';
                ctx.lineWidth = 1;
                const gridSpacing = 25;
                for (let x = 0; x < width; x += gridSpacing) {
                    ctx.beginPath();
                    ctx.moveTo(x, 0);
                    ctx.lineTo(x, height);
                    ctx.stroke();
                }
                for (let y = 0; y < height; y += gridSpacing) {
                    ctx.beginPath();
                    ctx.moveTo(0, y);
                    ctx.lineTo(width, y);
                    ctx.stroke();
                }
                ctx.restore();
                // Non-linear Euler-Cromer dynamic pendulum swing steps if running
                if (state.isRunning) {
                    // Sub-integrate to maintain stability
                    const subSteps = 6;
                    const subDt = dt / subSteps;
                    for (let step = 0; step < subSteps; step++) {
                        // d^2theta/dt^2 = -(g / L) * sin(theta) - (b / m) * omega
                        const alpha = -(state.gravity / state.length) * Math.sin(state.theta) - (state.damping / state.mass) * state.omega;
                        state.omega += alpha * subDt;
                        state.theta += state.omega * subDt;
                    }
                    // Display live values
                    txtLiveOmega.innerText = state.omega.toFixed(2) + " rad/s";
                    const speed = Math.abs(state.length * state.omega);
                    txtLiveSpeed.innerText = speed.toFixed(2) + " m/s";
                }
                // Geometry definitions
                const pivotX = width / 2;
                const pivotY = 55;
                // Dynamic auto-zoom: scale so pendulum fills ~75% of available canvas height
                // Available height = canvas height minus pivot top margin and bottom energy bar
                const availH = height - pivotY - 170; // 170 for energy bar at bottom
                const scaleLengthPx = Math.max(40, availH / Math.max(state.length, 0.5));
                const visualLength = state.length * scaleLengthPx;
                // Bob location
                // angle theta (theta = 0 is straight down)
                const bobX = pivotX + visualLength * Math.sin(state.theta);
                const bobY = pivotY + visualLength * Math.cos(state.theta);
                // Swing trail trace
                if (state.isRunning) {
                    state.swingPathHistory.push({ x: bobX, y: bobY });
                    if (state.swingPathHistory.length > 50) {
                        state.swingPathHistory.shift();
                    }
                }
                // A. Draw Swing Path Dotted Trace
                if (state.swingPathHistory.length > 1) {
                    ctx.save();
                    ctx.strokeStyle = "rgba(219, 39, 119, 0.25)";
                    ctx.lineWidth = 2;
                    ctx.beginPath();
                    for (let i = 0; i < state.swingPathHistory.length; i++) {
                        const pt = state.swingPathHistory[i];
                        if (i === 0) {
                            ctx.moveTo(pt.x, pt.y);
                        } else {
                            ctx.lineTo(pt.x, pt.y);
                        }
                    }
                    ctx.stroke();
                    ctx.restore();
                }
                // B. Draw Hanging Steel Rod
                ctx.save();
                ctx.strokeStyle = "#475569";
                ctx.lineWidth = 3.5;
                ctx.beginPath();
                ctx.moveTo(pivotX, pivotY);
                ctx.lineTo(bobX, bobY);
                ctx.stroke();
                ctx.restore();
                // C. Draw Pivot mount structure
                ctx.save();
                ctx.fillStyle = "#ffffff";
                ctx.strokeStyle = "#334155";
                ctx.lineWidth = 3.0;
                ctx.beginPath();
                ctx.rect(pivotX - 14, pivotY - 8, 28, 16);
                ctx.fill();
                ctx.stroke();
                // Pivot pin
                ctx.fillStyle = "#475569";
                ctx.beginPath();
                ctx.arc(pivotX, pivotY, 4, 0, Math.PI * 2);
                ctx.fill();
                ctx.restore();
                // D. Draw Bob Sphere (diameter linear to mass)
                const bobRadius = 10.0 + Math.pow(state.mass, 0.33) * 12.0;
                ctx.save();
                ctx.fillStyle = "#ffffff";
                ctx.strokeStyle = "#0284c7";
                ctx.lineWidth = 4;
                ctx.beginPath();
                ctx.arc(bobX, bobY, bobRadius, 0, Math.PI * 2);
                ctx.fill();
                ctx.stroke();
                // Render dynamic text on bob indicating angle
                ctx.fillStyle = "#1e293b";
                ctx.font = "bold 9px Inter, sans-serif";
                ctx.textAlign = "center";
                const currentDeg = (state.theta * 180.0) / Math.PI;
                ctx.fillText(Math.round(currentDeg) + "°", bobX, bobY + 3);
                ctx.restore();
                // 1. 줄 중간에 찰랑거리며 흡착하는 길이 라벨링
                ctx.save();
                ctx.fillStyle = "#475569";
                ctx.font = "bold 10px Inter, sans-serif";
                ctx.textAlign = "left";
                const midX = (pivotX + bobX) / 2;
                const midY = (pivotY + bobY) / 2;
                const angle = state.theta;
                const nx = Math.cos(angle);
                const ny = -Math.sin(angle);
                ctx.fillText("L = " + state.length.toFixed(1) + "m", midX + nx * 12, midY + ny * 12);
                ctx.restore();
                // 2. 추 상단 외곽에 동화되어 주행하는 질량 라벨링
                ctx.save();
                ctx.fillStyle = "var(--color-magenta)";
                ctx.font = "bold 10px Outfit, sans-serif";
                ctx.textAlign = "center";
                ctx.fillText("M = " + state.mass.toFixed(1) + "kg", bobX, bobY - bobRadius - 8);
                ctx.restore();
                // 3. 우측 상단 실시간 단진동 설계 사양 모니터 카드 (100% 완전 불투명 순백색 배경)
                ctx.save();
                const specW = 145;
                const specH = 75;
                const specX = width - specW - 15;
                const specY = height - specH - 15; // 최우측 하단으로 전격 배치하여 겹침 영구 박멸!
                ctx.fillStyle = "rgba(255, 255, 255, 1.0)";
                ctx.strokeStyle = "rgba(0, 0, 0, 0.08)";
                ctx.lineWidth = 1.5;
                ctx.beginPath();
                ctx.rect(specX, specY, specW, specH);
                ctx.fill();
                ctx.stroke();
                ctx.fillStyle = "#1e293b";
                ctx.font = "bold 9.5px Outfit, sans-serif";
                ctx.fillText("실시간 단진동 설계 사양", specX + 10, specY + 16);
                ctx.fillStyle = "rgba(71, 85, 105, 0.9)";
                ctx.font = "500 8.5px Inter, sans-serif";
                ctx.fillText("&#x1f4cf; 진자 길이 (L): " + state.length.toFixed(1) + " m", specX + 10, specY + 32);
                ctx.fillText("&#x2696; 추의 질량 (M): " + state.mass.toFixed(1) + " kg", specX + 10, specY + 47);
                let gName = "지구";
                if (state.gravity === 24.79) gName = "목성";
                if (state.gravity === 1.62) gName = "달";
                ctx.fillText("&#x1fa90; 중력가속도 (g): " + state.gravity.toFixed(2) + " (" + gName + ")", specX + 10, specY + 62);
                ctx.restore();
                // E. Render real-time Tension, Gravity dynamic Vector arrows on the bob
                ctx.save();
                // 1. Gravity arrow straight down - Purple
                // Dynamic vector scale: max arrow ~40% of pendulum visual length, normalized by force
                const maxArrowLen = Math.min(60, visualLength * 0.4);
                const wForce = state.mass * state.gravity;
                const vectorScale = maxArrowLen / Math.max(wForce, 5);
                ctx.strokeStyle = "#7c3aed";
                ctx.lineWidth = 2.5;
                ctx.beginPath();
                ctx.moveTo(bobX, bobY);
                ctx.lineTo(bobX, bobY + wForce * vectorScale);
                ctx.stroke();
                // 2. Tension arrow along the rod towards pivot - Cyan
                const liveTension = state.mass * state.gravity * Math.cos(state.theta) + state.mass * state.length * state.omega * state.omega;
                // direction from bob to pivot:
                const dx = pivotX - bobX;
                const dy = pivotY - bobY;
                const dLen = Math.sqrt(dx*dx + dy*dy);
                if (dLen > 0.01) {
                    const tx = (dx / dLen) * liveTension * vectorScale;
                    const ty = (dy / dLen) * liveTension * vectorScale;
                    ctx.strokeStyle = "#0284c7";
                    ctx.lineWidth = 2.5;
                    ctx.beginPath();
                    ctx.moveTo(bobX, bobY);
                    ctx.lineTo(bobX + tx, bobY + ty);
                    ctx.stroke();
                }
                ctx.restore();
                // F. Render real-time Energy Conservation Bar meters (PE / KE / Total) - Scaled Up & Korean Labels!
                ctx.save();
                const barX = 15; // 좌측 밀착
                const barY = height - 150; // 하단 안착
                const barWidth = 200; // 130 -> 200px로 대폭 확장
                const barHeight = 130; // 85 -> 130px로 대폭 확장
                // 100% 불투명 순백색 배경 마스킹
                ctx.fillStyle = "rgba(255, 255, 255, 1.0)";
                ctx.strokeStyle = "rgba(0, 0, 0, 0.08)";
                ctx.lineWidth = 1.5;
                ctx.beginPath();
                ctx.rect(barX, barY, barWidth, barHeight);
                ctx.fill();
                ctx.stroke();
                // Energy variables
                const pe = state.mass * state.gravity * state.length * (1.0 - Math.cos(state.theta));
                const linearVel = state.length * state.omega;
                const ke = 0.5 * state.mass * linearVel * linearVel;
                const te = pe + ke; // total energy
                // Max absolute energy for scaling (based on initial PE)
                const initialRad = (state.ang0 * Math.PI) / 180.0;
                const maxEnergy = Math.max(state.mass * state.gravity * state.length * (1.0 - Math.cos(initialRad)), 5.0);
                // 세로 스케일 최대 68px로 조절하여 상단 제목 겹침 완벽 소멸!
                const peBarH = Math.max(0, (pe / maxEnergy) * 68.0);
                const keBarH = Math.max(0, (ke / maxEnergy) * 68.0);
                const teBarH = Math.max(0, (te / maxEnergy) * 68.0);
                const chartBottomY = barY + barHeight - 28;
                // 1. 위치에너지 (PE Bar - Magenta, 폭 20px)
                ctx.fillStyle = "#db2777";
                ctx.beginPath();
                ctx.rect(barX + 25, chartBottomY - peBarH, 20, peBarH);
                ctx.fill();
                // 2. 운동에너지 (KE Bar - Cobalt Blue, 폭 20px)
                ctx.fillStyle = "#0284c7";
                ctx.beginPath();
                ctx.rect(barX + 85, chartBottomY - keBarH, 20, keBarH);
                ctx.fill();
                // 3. 역학적에너지 (TE Bar - Green, 폭 20px)
                ctx.fillStyle = "#10b981";
                ctx.beginPath();
                ctx.rect(barX + 145, chartBottomY - teBarH, 20, teBarH);
                ctx.fill();
                // 4. 에너지 바 꼭대기 실시간 J 수치 표기 (데이터 연동형)
                ctx.fillStyle = "rgba(71, 85, 105, 0.95)";
                ctx.font = "bold 8.5px Inter, sans-serif";
                ctx.textAlign = "center";
                ctx.fillText(pe.toFixed(1) + "J", barX + 35, chartBottomY - peBarH - 5);
                ctx.fillText(ke.toFixed(1) + "J", barX + 95, chartBottomY - keBarH - 5);
                ctx.fillText(te.toFixed(1) + "J", barX + 155, chartBottomY - teBarH - 5);
                // 5. 한글 약어 2단 복합 축 라벨링
                ctx.fillStyle = "#475569";
                ctx.font = "bold 9.5px Inter, sans-serif";
                ctx.textAlign = "center";
                ctx.fillText("위치", barX + 35, barY + barHeight - 16);
                ctx.font = "500 7.5px Inter, sans-serif";
                ctx.fillText("(PE)", barX + 35, barY + barHeight - 6);
                ctx.font = "bold 9.5px Inter, sans-serif";
                ctx.fillText("운동", barX + 95, barY + barHeight - 16);
                ctx.font = "500 7.5px Inter, sans-serif";
                ctx.fillText("(KE)", barX + 95, barY + barHeight - 6);
                ctx.font = "bold 9.5px Inter, sans-serif";
                ctx.fillText("역학", barX + 155, barY + barHeight - 16);
                ctx.font = "500 7.5px Inter, sans-serif";
                ctx.fillText("(TE)", barX + 155, barY + barHeight - 6);
                ctx.textAlign = "left";
                ctx.fillStyle = "#1e293b";
                ctx.font = "bold 9.5px Outfit, sans-serif";
                ctx.fillText("에너지 평형 모니터", barX + 8, barY + 14);
                ctx.restore();
            }
            // Sync preset and run initial calculations
            loadPreset('grandfather');
            requestAnimationFrame(animate);
            // Right-click & Keyboard shortcuts block
            document.addEventListener('contextmenu', function(e) {
                e.preventDefault();
                alert("이 콘텐츠는 저작권법의 보호를 받습니다. 무단 복제 및 우클릭을 금지합니다.");
                return false;
            }, { capture: true });
            document.addEventListener('selectstart', function(e) {
                e.preventDefault();
                return false;
            }, { capture: true });
            document.addEventListener('keydown', function(e) {
                if (e.key === 'F12') {
                    e.preventDefault();
                    alert("이 콘텐츠는 저작권법의 보호를 받습니다. 무단 복제 및 우클릭을 금지합니다.");
                    return false;
                }
                if (e.ctrlKey) {
                    if (e.key === 'u' || e.key === 'c' || e.key === 's' || e.key === 'U' || e.key === 'C' || e.key === 'S') {
                        e.preventDefault();
                        alert("이 콘텐츠는 저작권법의 보호를 받습니다. 무단 복제 및 우클릭을 금지합니다.");
                        return false;
                    }
                    if (e.shiftKey) {
                        if (['i','I','j','J','c','C'].includes(e.key)) {
                            e.preventDefault();
                            alert("이 콘텐츠는 저작권법의 보호를 받습니다. 무단 복제 및 우클릭을 금지합니다.");
                            return false;
                        }
                    }
                }
            }, { capture: true });
        }
        let initAttempts = 0;
        function tryInit() {
            initAttempts++;
            initSimulator();
            if (!window.__pendulum_initialized) {
                if (initAttempts < 50) {
                    setTimeout(tryInit, 100);
                }
            }
        }
        if (document.readyState === 'complete' || document.readyState === 'interactive') {
            tryInit();
        } else {
            document.addEventListener('DOMContentLoaded', tryInit);
            window.addEventListener('load', tryInit);
        }
        })();
</script>


<div style="background: linear-gradient(135deg, rgba(0,242,254,0.03), rgba(138,43,226,0.03)); border: 1px solid rgba(0,242,254,0.15); border-radius: 12px; padding: 18px 24px; margin: 25px auto 35px auto; font-size: 0.95em; color: #4b5563; line-height: 1.7; font-family: sans-serif;">
    <strong style="color: #1f2937; font-size: 1.05em; display: flex; align-items: center; gap: 8px;">
        <span style="font-size: 1.2em;"><img src="https://s.w.org/images/core/emoji/17.0.2/72x72/1f4a1.png" alt="💡" class="wp-smiley" style="height: 1em; max-height: 1em;" /></span> 간편 사용 설명서
    </strong>
    <ol style="margin: 10px 0 0 0; padding-left: 20px;">
        <li style="margin-bottom: 6px;"><strong>진자 길이 및 질량 조절: 매달린 진자의 Rod 길이(0.5m ~ 4m)와 추의 실질 질량(kg)을 설정합니다.</strong></li>
<li style="margin-bottom: 6px;">초기 각도(θ) 및 감쇠율(b) 지정: 진자를 한쪽으로 당겨 놓는 초기 낙하 각도(Degree)와 공기 마찰 등으로 운동 에너지를 상실시키는 감쇠 마찰 계수를 조절합니다.</li>
<li style="margin-bottom: 6px;">중력장 천체 선택: 지구(9.81), 목성(24.79), 달(1.62) 등 진자가 스윙할 우주 중력 환경을 선택합니다.</li>
<li style="margin-bottom: 6px;">실시간 장력 및 에너지 모니터링: 진자가 요동치면서 변하는 유기 장력(Tension)과 에너지(PE/KE) 막대바의 실시간 유기 변동 상태를 관측합니다.</li>
    </ol>
</div>


<details class="premium-seo-accordion" style="border: 1px solid rgba(0,0,0,0.08); border-radius: 12px; background: #fbfbfc; padding: 0; margin: 30px auto; box-shadow: 0 4px 6px -1px rgba(0,0,0,0.01); font-family: sans-serif;">
    <summary style="display: flex; justify-content: space-between; align-items: center; padding: 20px 24px; font-size: 1.1em; font-weight: 700; color: #1f2937; cursor: pointer; user-select: none; outline: none; list-style: none;">
        <span><img src="https://s.w.org/images/core/emoji/17.0.2/72x72/1f4da.png" alt="📚" class="wp-smiley" style="height: 1em; max-height: 1em;" /> 상세 단진자 운동 주기 및 물리 에너지 공식 해설</span>
        <span class="accordion-arrow" style="font-size: 0.9em; color: #9ca3af; transition: transform 0.2s ease;">▼</span>
    </summary>
    <div style="padding: 0 24px 24px 24px; border-top: 1px solid rgba(0,0,0,0.04); background: #ffffff; border-radius: 0 0 12px 12px; font-size: 0.98em; color: #374151; line-height: 1.8;">
        <div style="margin-top: 20px;">
            <h3>1. 단순 조화 진동(Simple Harmonic Motion)과 비선형 단진동 방정식</h3>
<p>일반적으로 물리학에서 다루는 진자의 주기는 미소 각도(&theta; &approx; sin&theta;) 가정을 통해 선형화되지만, 본 시뮬레이터는 대각도 발진 상태에서도 오차가 없도록 다음의 <strong>비선형 2계 미분방정식</strong>을 실시간 수치 해석(Euler-Cromer integration)합니다.</p><p style="text-align: center; font-weight: bold; background: #f3f4f6; padding: 12px; border-radius: 8px;">d&sup2;&theta;/dt&sup2; + (b/m)&middot;d&theta;/dt + (g/L)&middot;sin(&theta;) = 0</p><p>여기서 <code>b</code>는 공기 감쇠력, <code>m</code>은 질량, <code>L</code>은 진자 길이, <code>g</code>는 중력가속도입니다. 감쇠가 0일 때는 에너지가 영구 보존되나 감쇠가 투입되면 운동 진폭이 지수함수적으로 수축하며 원점에 수렴합니다.</p>
<h3>2. 진자 로드에 유도되는 동적 장력(Tension) 계산식</h3>
<p>진자가 각도 <code>&theta;</code>인 상태에서 로드에 유도되는 <strong>동적 장력 (Tension Force, F_T)</strong>은 원심력과 중력 분력의 벡터 합성 결과입니다.</p><p style="text-align: center; font-weight: bold; background: #e0f2fe; padding: 16px; border-radius: 8px; font-size: 1.05em; color: #0369a1;">F_T = m &times; g &times; cos(&theta;) + m &times; L &times; &omega;&sup2; &nbsp;[N]</p><p>여기서 <code>&omega; = d&theta;/dt</code>(각속도, rad/s)입니다. 진자가 가장 아래인 수직 중심선(&theta; = 0)을 통과할 때 속도가 최고조에 이르며 동적 장력이 극대값을 형성하고, 반대로 스윙 정점(&theta; = &theta;_max)에서는 각속도 <code>&omega; = 0</code>이 되므로 단순 <code>m&middot;g&middot;cos&theta;</code>의 순수 정하중만 작용하게 됩니다.</p>
<h3>3. 에너지 보존 법칙과 감쇠 감쇠 소실율</h3>
<p>단진자 계의 전체 기계적 에너지 합 <code>E_total</code>은 아래의 두 성분으로 결합됩니다.</p><ul><li><strong>위치 에너지 (Potential Energy, PE):</strong> 기준 최하점으로부터 상승한 높이에 따른 에너지입니다. <code>PE = m &times; g &times; L &times; (1 - cos&theta;) &nbsp;[J]</code></li><li><strong>운동 에너지 (Kinetic Energy, KE):</strong> 추의 궤도 접선 선형 속도에 기인합니다. <code>KE = 1/2 &times; m &times; (L&middot;&omega;)&sup2; &nbsp;[J]</code></li></ul><p>공기 마찰 저항이 존재하면 스윙할 때마다 열에너지로 감쇠 마찰 손실이 발생하여 총 에너지는 지속적으로 감량되며 계의 무질서도를 형성합니다.</p>
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