This is the 11503rd most frequent Korean word.
끝마친
"끝마친" means "finished" or "completed."
In this sentence, '끝마친' describes the state of the work being completed ('일'), indicating an action finalized prior to the following event (rest).
그는 일을 끝마친 후 쉬고 싶었다.
He wanted to rest after finishing his work.
Here, '끝마친' modifies '프로젝트 보고서' to emphasize that the report has been finalized.
끝마친 프로젝트 보고서는 팀장에게 전달되었다.
The completed project report was delivered to the team leader.
In this context, '끝마친' describes '과제' as something that has been completed and requires review before submission.