diff --git a/hyewon/3-customVideoPlayer/README.md b/hyewon/3-customVideoPlayer/README.md
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+# 목차
+- `<video>` 요소
+- loadedmetadata
+- Event listener 중첩
+
+## `<video>` 요소
+- - -
+- 비디오 플레이백을 지원하는 미디어 플레이어를 문서에 삽입한다.
+
+### Properties
+- - -
+<br /> | Description
+|--|--|
+src | 삽입할 동영상의 주소
+poster | 동영상 재생/탐색하기 전까지 출력되는 포스터 프레임 주소
+currentTime | 현재 재생 위치
+duration | video 전체 길이
+
+### Methods
+- - -
+<br /> | Description
+|--|--|
+play() | 재생 시작
+pause() | 일시정지
+
+### Events
+- - -
+<br /> | Description
+|--|--|
+ended | 현재 video 가 끝났을 때
+loadedmetadata | 브라우저가 video 에 대한 메타 데이터를 로드했을 때
+pause | video 가 일시정지 되었을 때
+play | video 가 시작되었거나 더이상 일시정지 되지 않았을 때
+timeupdate | 현재 재생위치가 변경되었을 때
+
+### 내 코드
+```javascript
+if($video.paused){
+    $video.play()
+    $playButton.classList.replace('fa-play', 'fa-pause')
+    return
+}
+```
+```javascript
+$video.currentTime = Math.trunc(currentPosition)
+```
+
+## loadedmetadata
+- - -
+- video 의 메타 데이터가 로드되면 해당 이벤트가 발생한다.
+- video 의 전체 길이를 가져오는 duration 속성은, **video 에 대한 로드가 끝나지 않은 시점에서 호출하면 NaN 값이 출력된다.**
+- 따라서 로드가 끝난 시점에서 duration 값을 호출하고 싶다면, **'lodaedmetadata'** 이벤트 리스너를 등록해야 한다.
+
+### 내 코드
+- - -
+```javascript
+$video.addEventListener('loadedmetadata', function() {
+    const duration = $video.duration
+```
+
+## Event listener 중첩
+- - -
+### 내 코드
+```javascript
+$video.addEventListener('loadedmetadata', function() {
+    const duration = $video.duration
+    const unit = ((parseFloat($progressBar.max) - parseFloat($progressBar.min)) / duration) / 4
+
+    $video.addEventListener('timeupdate', e => {
+        $progressBar.value = parseFloat($progressBar.value) + unit
+        // 생략
+    })
+    
+    $progressBar.addEventListener('change', e => {
+        const currentPosition = duration * $progressBar.value / (parseFloat($progressBar.max)
+        // 생략
+    })
+})
+```
+loadedmetadata 항목의 설명에서도 언급했듯이, duration 은 메타데이터가 로드된 이후에 호출하는 것이 안전하다. 그럼 duration 과 관련된 변수를 사용하는 event listener 들은 loadedmetadata 로 duration 을 가져온 이후에 실행됨이 보장되어야 할 것 같은데, 그렇게 할 만한 방법이 중첩밖에 생각나지 않았다... 이게 효율적인 방법인지는 잘 모르겠다... (nested event listener 이런 식으로 서치해 봤는데 좋은 정보를 얻지 못했다.)
+
+## 참조
+- - -
+- `<video>` 요소 <br />
+https://developer.mozilla.org/ko/docs/Web/HTML/Element/Video <br />
+https://html.spec.whatwg.org/#the-video-element <br />
+https://www.w3schools.com/tags/ref_av_dom.asp <br />
+- loadedmetadata <br />
+https://m.blog.naver.com/PostView.naver?isHttpsRedirect=true&blogId=ivory82&logNo=220096880567 <br />
diff --git a/hyewon/3-customVideoPlayer/css/progress.css b/hyewon/3-customVideoPlayer/css/progress.css
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+/* SOURCE: https://css-tricks.com/styling-cross-browser-compatible-range-inputs-css/ */
+
+input[type='range'] {
+	-webkit-appearance: none; /* Hides the slider so that custom slider can be made */
+	width: 100%; /* Specific width is required for Firefox. */
+	background: transparent; /* Otherwise white in Chrome */
+}
+
+input[type='range']::-webkit-slider-thumb {
+	-webkit-appearance: none;
+}
+
+input[type='range']:focus {
+	outline: none; /* Removes the blue border. You should probably do some kind of focus styling for accessibility reasons though. */
+}
+
+input[type='range']::-ms-track {
+	width: 100%;
+	cursor: pointer;
+
+	/* Hides the slider so custom styles can be added */
+	background: transparent;
+	border-color: transparent;
+	color: transparent;
+}
+
+/* Special styling for WebKit/Blink */
+input[type='range']::-webkit-slider-thumb {
+	-webkit-appearance: none;
+	border: 1px solid #000000;
+	height: 36px;
+	width: 16px;
+	border-radius: 3px;
+	background: #ffffff;
+	cursor: pointer;
+	margin-top: -14px; /* You need to specify a margin in Chrome, but in Firefox and IE it is automatic */
+	box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d; /* Add cool effects to your sliders! */
+}
+
+/* All the same stuff for Firefox */
+input[type='range']::-moz-range-thumb {
+	box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+	border: 1px solid #000000;
+	height: 36px;
+	width: 16px;
+	border-radius: 3px;
+	background: #ffffff;
+	cursor: pointer;
+}
+
+/* All the same stuff for IE */
+input[type='range']::-ms-thumb {
+	box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+	border: 1px solid #000000;
+	height: 36px;
+	width: 16px;
+	border-radius: 3px;
+	background: #ffffff;
+	cursor: pointer;
+}
+
+input[type='range']::-webkit-slider-runnable-track {
+	width: 100%;
+	height: 8.4px;
+	cursor: pointer;
+	box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+	background: #3071a9;
+	border-radius: 1.3px;
+	border: 0.2px solid #010101;
+}
+
+input[type='range']:focus::-webkit-slider-runnable-track {
+	background: #367ebd;
+}
+
+input[type='range']::-moz-range-track {
+	width: 100%;
+	height: 8.4px;
+	cursor: pointer;
+	box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+	background: #3071a9;
+	border-radius: 1.3px;
+	border: 0.2px solid #010101;
+}
+
+input[type='range']::-ms-track {
+	width: 100%;
+	height: 8.4px;
+	cursor: pointer;
+	background: transparent;
+	border-color: transparent;
+	border-width: 16px 0;
+	color: transparent;
+}
+input[type='range']::-ms-fill-lower {
+	background: #2a6495;
+	border: 0.2px solid #010101;
+	border-radius: 2.6px;
+	box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+}
+input[type='range']:focus::-ms-fill-lower {
+	background: #3071a9;
+}
+input[type='range']::-ms-fill-upper {
+	background: #3071a9;
+	border: 0.2px solid #010101;
+	border-radius: 2.6px;
+	box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
+}
+input[type='range']:focus::-ms-fill-upper {
+	background: #367ebd;
+}
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diff --git a/hyewon/3-customVideoPlayer/css/style.css b/hyewon/3-customVideoPlayer/css/style.css
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+@import url('https://fonts.googleapis.com/css?family=Questrial&display=swap');
+
+* {
+  box-sizing: border-box;
+}
+
+body {
+  font-family: 'Questrial', sans-serif;
+  background-color: #666;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  max-height: 100vh;
+  margin: 0;
+}
+
+h1 {
+  color: #fff;
+}
+
+.screen {
+  cursor: pointer;
+  width: 60%;
+  background-color: #000 !important;
+  border-top-left-radius: 10px;
+  border-top-right-radius: 10px;
+}
+
+.controls {
+  background: #333;
+  color: #fff;
+  width: 60%;
+  border-bottom-left-radius: 10px;
+  border-bottom-right-radius: 10px;
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  padding: 10px;
+}
+
+.controls .btn {
+  border: 0;
+  background: transparent;
+  cursor: pointer;
+}
+
+.controls .fa-play {
+  color: #28a745;
+}
+
+.controls .fa-stop {
+  color: #dc3545;
+}
+
+.controls .fa-pause {
+  color: #fff;
+}
+
+.controls .timestamp {
+  color: #fff;
+  font-weight: bold;
+  margin-left: 10px;
+}
+
+.btn:focus {
+  outline: 0;
+}
+
+@media (max-width: 800px) {
+  .screen,
+  .controls {
+    width: 90%;
+  }
+}
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diff --git a/hyewon/3-customVideoPlayer/img/poster.png b/hyewon/3-customVideoPlayer/img/poster.png
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diff --git a/hyewon/3-customVideoPlayer/index.html b/hyewon/3-customVideoPlayer/index.html
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+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
+    <title>Custom Video Player</title>
+    <link
+      href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css"
+      rel="stylesheet"
+      integrity="sha384-wvfXpqpZZVQGK6TAh5PVlGOfQNHSoD2xbE+QkPxCAFlNEevoEH3Sl0sibVcOQVnN"
+      crossorigin="anonymous"
+    />
+    <link rel="stylesheet" href="css/progress.css" />
+    <link rel="stylesheet" href="css/style.css" />
+  </head>
+  <body>
+    <h1>Custom Video Player</h1>
+    <video
+      src="videos/gone.mp4"
+      id="video"
+      class="screen"
+      poster="img/poster.png"
+      onclick="videoPlay()"
+    ></video>
+    <div class="controls">
+      <button class="btn" id="play" onclick="videoPlay()">
+        <i class="fa fa-play fa-2x"></i>
+      </button>
+      <button class="btn" id="stop" onclick="stop()">
+        <i class="fa fa-stop fa-2x"></i>
+      </button>
+      <input
+        type="range"
+        id="progress"
+        class="progress"
+        min="0"
+        max="100"
+        step="0.1"
+        value="0"
+      />
+      <span class="timestamp" id="timestamp">00:00</span>
+    </div>
+
+    <script src="script.js"></script>
+  </body>
+</html>
+
+<!-- https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Video_and_audio_APIs -->
\ No newline at end of file
diff --git a/hyewon/3-customVideoPlayer/script.js b/hyewon/3-customVideoPlayer/script.js
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+const $video = document.getElementById('video')
+const $playButton = document.querySelector('.controls .btn#play .fa')
+const $progressBar = document.getElementById('progress')
+const $timestamp = document.getElementById('timestamp')
+
+function videoPlay() {
+    if($video.paused){
+        $video.play()
+        $playButton.classList.replace('fa-play', 'fa-pause')
+        return
+    }
+    if($video.played) {
+        $video.pause()
+        $playButton.classList.replace('fa-pause', 'fa-play')
+        return
+    }
+}
+
+function stop() {
+    $video.currentTime = 0
+    $video.pause()
+    if($playButton.classList.contains('fa-pause')){
+        $playButton.classList.replace('fa-pause', 'fa-play')
+    }
+    $progressBar.value = 0
+}
+
+$video.addEventListener('loadedmetadata', function() {
+    const duration = $video.duration
+    const unit = ((parseFloat($progressBar.max) - parseFloat($progressBar.min)) / duration) / 4
+
+    $video.addEventListener('timeupdate', e => {
+        $progressBar.value = parseFloat($progressBar.value) + unit
+        const min = Math.trunc(Math.trunc($video.currentTime) / 60)
+        const sec = Math.trunc(Math.trunc($video.currentTime) % 60)
+        const time = ((min >= 10 ) ? `${min}` : ("0" + `${min}`)) + ((sec >= 10) ? `:${sec}` : (":0" + `${sec}`))
+        $timestamp.textContent = time
+        if($video.ended) {
+            $playButton.classList.replace('fa-pause', 'fa-play')
+        }
+    })
+    
+    $progressBar.addEventListener('change', e => {
+        const currentPosition = duration * $progressBar.value / (parseFloat($progressBar.max) - parseFloat($progressBar.min))
+        $video.currentTime = Math.trunc(currentPosition)
+    })
+})
\ No newline at end of file
diff --git a/hyewon/3-customVideoPlayer/videos/gone.mp4 b/hyewon/3-customVideoPlayer/videos/gone.mp4
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