This is the 4090th most frequent Korean word.
작성한
"작성한" means "written" or "created."
Here, '작성한' (completed) is used to modify the noun '보고서를' (report), indicating the action of having completed it.
나는 보고서를 작성한 후에 제출했다.
I completed the report and then submitted it.
In this sentence, '작성한' is used as a modifier for '이메일' (email), indicating that you are the one who wrote it.
당신이 작성한 이메일은 정말 감동적이었어요.
The email you wrote was really touching.
'작성한' modifies '데이터' (data) to show that the user was the one who provided or created the data.