사각지대가 · 사각지대를
blind spot; area left unprotected or overlooked
Example
복지 사각지대에 놓인 노인들이 여전히 많습니다.
There are still many elderly people left in the blind spots of the welfare system.
Word parts
사 dead+각 angle+지 land+대 zone
Literally 'dead-angle zone', where you can't see.
Good to know
Pronounced [사각찌대]; in news it often means people the system fails to reach, as in 복지 사각지대.