지하철 열차 혼잡도는 어떻게 아는 걸까?

<div class="figure-img" data-ke-type="image" data-ke-style="alignCenter" data-ke-mobilestyle="widthOrigin" data-link="https://cafe.daum.net/baemilytory/91cd/949278" data-link-newwindow="_blank"><a href="https://cafe.daum.net/baemilytory/91cd/949278" target="_blank" class="ke-link"><img src="https://t1.daumcdn.net/cafeattach/1Yeqd/bb8b7e2cf0556b78a6a5841883b6cbf69674a68d" data-img-src="https://t1.daumcdn.net/cafeattach/1Yeqd/bb8b7e2cf0556b78a6a5841883b6cbf69674a68d" data-origin-width="480" data-origin-height="120"></a></div><p> 출처: <a href="https://youtu.be/Dc2-4neZ8Rs?si=yzuCaZwL4hdVLLYM" target="_blank" class="ke-link">https://youtu.be/Dc2-4neZ8Rs?si=yzuCaZwL4hdVLLYM</a></p><div class="figure-video" data-ke-type="video" data-video-url="https://www.youtube.com/watch?v=Dc2-4neZ8Rs" data-video-host="youtube" data-video-play-service="daum_cafe" data-video-width="1280" data-video-height="720" data-ke-style="alignCenter" data-video-thumbnail="http://scrap.kakaocdn.net/dn/rn2mr/bl4IRJkf6EE/DE4Z2OhJaHjkS1EgdARIrK/kakaolink40_original.jpg?width=1280&height=720" data-ke-mobile-mobileStyle="widthFull" data-video-origin-width="1280" data-video-origin-height="720"><iframe src="https://www.youtube.com/embed/Dc2-4neZ8Rs" width="1280" height="720" frameborder="0" scrolling="no" allowfullscreen=""></iframe><div class="figcaption"></div></div><div class="figure-img" data-ke-type="image" data-ke-style="alignCenter" data-ke-mobilestyle="widthOrigin"><img src="https://t1.daumcdn.net/cafeattach/1Yeqd/33c481a37b99bfc96e83d3618bce5b633a28c8d8" class="txc-image" data-img-src="https://t1.daumcdn.net/cafeattach/1Yeqd/33c481a37b99bfc96e83d3618bce5b633a28c8d8" data-origin-width="2556" data-origin-height="1179"></div><p style="text-align: left;">신형 지하철 탔으면 한 번쯤 봤을 이거<br>어떻게 아는 건지 궁금하지 않아?<br></p><div class="figure-img" data-ke-type="image" data-ke-style="alignCenter" data-ke-mobilestyle="widthOrigin"><img src="https://t1.daumcdn.net/cafeattach/1Yeqd/3e57b8cdfdf40175aa50aea8299bc6d87c40ce43" class="txc-image" data-img-src="https://t1.daumcdn.net/cafeattach/1Yeqd/3e57b8cdfdf40175aa50aea8299bc6d87c40ce43" data-origin-width="2556" data-origin-height="1179"></div><div class="figure-img" data-ke-type="image" data-ke-style="alignCenter" data-ke-mobilestyle="widthOrigin"><img src="https://t1.daumcdn.net/cafeattach/1Yeqd/5f516a48d104c96cbdce203c844841df32e0729e" class="txc-image" data-img-src="https://t1.daumcdn.net/cafeattach/1Yeqd/5f516a48d104c96cbdce203c844841df32e0729e" data-origin-width="2556" data-origin-height="1179"></div><p style="text-align: left;">이렇게 열차엔 무게 측정 하중감지 센터가 있대<br>재차 승객 무게를 재서 성인 평균 몸무게인 65kg로 나눠서 표시하는 거래</p><div class="figure-img" data-ke-type="image" data-ke-style="alignCenter" data-ke-mobilestyle="widthOrigin"><img src="https://t1.daumcdn.net/cafeattach/1Yeqd/57fa9d8bc806453bd1cd3366dc85e11f0f868e32" class="txc-image" data-img-src="https://t1.daumcdn.net/cafeattach/1Yeqd/57fa9d8bc806453bd1cd3366dc85e11f0f868e32" data-origin-width="2556" data-origin-height="1179"></div><p style="text-align: left;">이렇게!<br><br>기준은</p><div class="figure-img" data-ke-type="image" data-ke-style="alignCenter" data-ke-mobilestyle="widthOrigin"><img src="https://t1.daumcdn.net/cafeattach/1Yeqd/60b39de581d06ca71ea517be88ba8d98d51bc3a6" class="txc-image" data-img-src="https://t1.daumcdn.net/cafeattach/1Yeqd/60b39de581d06ca71ea517be88ba8d98d51bc3a6" data-origin-width="2556" data-origin-height="1179"></div><div class="figure-img" data-ke-type="image" data-ke-style="alignCenter" data-ke-mobilestyle="widthOrigin"><img src="https://t1.daumcdn.net/cafeattach/1Yeqd/2f1b469b0c2339d79ae311ec848ffa9b3a526a2c" class="txc-image" data-img-src="https://t1.daumcdn.net/cafeattach/1Yeqd/2f1b469b0c2339d79ae311ec848ffa9b3a526a2c" data-origin-width="2556" data-origin-height="1179"></div><div class="figure-img" data-ke-type="image" data-ke-style="alignCenter" data-ke-mobilestyle="widthOrigin"><img src="https://t1.daumcdn.net/cafeattach/1Yeqd/bfc68e0b576496342066c6ce3c6000121a01985f" class="txc-image" data-img-src="https://t1.daumcdn.net/cafeattach/1Yeqd/bfc68e0b576496342066c6ce3c6000121a01985f" data-origin-width="2556" data-origin-height="1179"></div><div class="figure-img" data-ke-type="image" data-ke-style="alignCenter" data-ke-mobilestyle="widthOrigin"><img src="https://t1.daumcdn.net/cafeattach/1Yeqd/e8709ae8b366e1c5cbc37246d1670a37af3b230f" class="txc-image" data-img-src="https://t1.daumcdn.net/cafeattach/1Yeqd/e8709ae8b366e1c5cbc37246d1670a37af3b230f" data-origin-width="2556" data-origin-height="1179"></div><p style="text-align: left;">이렇게<br><br>버스는 카드 찍는 걸로 계산한대<br><br>그럼 안녕<br></p>