This is the 3032nd most frequent Korean word.
한국계
"한국계" means "of Korean descent" or "Korean origin."
한국계 here describes the ethnic background of the person, indicating they have Korean heritage.
저는 한국계 미국인입니다.
I am Korean-American.
한국계 is used to describe individuals who have a Korean background, emphasizing their relation to Korean heritage.
한국계 사람들과 한국 문화를 공부하는 게 재미있어요.
Studying Korean culture and people of Korean descent is fun.
한국계 specifies that the person has Korean ancestry while being described as also having Japanese background.