동참했던

In a sentence

• 그는 자선 단체의 활동에 동참했던 과거를 자랑스럽게 여깁니다.

  He is proud of the past where he had participated in charitable activities.

  Here, "동참했던" is used to describe a past participation in the activities of a charitable organization, conveying active involvement.

• 이 프로젝트는 많은 사람들이 동참했던 중요한 사회적 운동의 일환이었어요.

  This project was part of an important social movement that many people had participated in.

  In this sentence, "동참했던" refers to the involvement of many people in a significant social initiative in the past.

• 그가 동참했던 그룹은 환경 보호 활동에 많은 기여를 했습니다.

  The group he had taken part in contributed significantly to the environmental protection activities.

  Here, "동참했던" is applied to illustrate the subject's affiliation with a group involved in environmental protection efforts.