기제가 · 기제를
mechanism (of how something works)
Example
스트레스가 몸에 영향을 주는 기제를 연구하고 있어요.
They are studying the mechanism by which stress affects the body.
Word parts
기 machine+제 control
Literally 'machine control' — the workings behind a process.
Good to know
Mostly in academic writing; in psychology, 방어 기제 means 'defense mechanism'.