This is the 17617th most frequent Korean word.
세웠던
"세웠던" means "that was set up" or "that was established."
The word "세웠던" in this sentence refers to actions taken in the past, specifically setting goals.
나는 어렸을 때 목표를 세웠던 기억이 있다.
I remember setting goals when I was young.
Here, "세웠던" describes the act of making plans in the past timeframe while appreciating past efforts.
그가 계획을 세웠던 노력은 감탄할 만하다.
His efforts in planning are admirable.
In this context, "세웠던" is used to refer to a strategy that was formulated previously and its current evaluation.