Let’s learn about "출입문 끼임 주의" on the platform screen doors of subway stations in Korea

출입문 끼임 주의 means "Watch out for door entrapment”

* 출입 : out and in (출 : go out, 입 : go in; come in)

* 문 : door

* 출입문 : door; gate

* 끼이다 : (1) be put [held] between; be caught in; get jammed [hemmed] in; be sandwiched between (2) be [lie] between; be sandwiched between (3) be tight [close] (4) take one's place among; rank with (5) [=미워하다•싫어하다] hate (people)

* 끼임 : a noun form of 끼이다 (-ㅁ : this suffix makes a verb a noun)

* 주의 : (1) [=조심] care, caution (2) [=관심] attention, caution (3) [=경고] warning, (formal) admonition (4) [=원칙] principle, [=신념] belief

* 주의하다 / 주의를 하다 : (1) [=조심하다] beware (of), be careful, be cautious (about) (2) [=관심을 가지다] give attention to, (formal) pay heed to, (formal) take head to (3) [=경고하다] warn, (formal) admonish

[About 스크린도어]

한국의 지하철에는 모두 스크린도어가 설치되어 있다.(All Korean subways have screen doors installed)

스크린도어에 대한 위키피디아의 설명은 다음과 같다.(Wikipedia's description of the screen door is as follows)

Platform screen doors, also known as platform edge doors, are used at some train or subway stations to separate the platform from train tracks, as well as on some bus rapid transit systems. They are primarily used for passenger safety (https://en.m.wikipedia.org/wiki/Platform_screen_doors)