때문이었으며

In a sentence

• 그 사고는 운전자의 부주의 때문이었으며 많은 피해를 초래했습니다.

  The accident was due to the driver's negligence and caused significant damage.

  '때문이었으며' is used to indicate a reason (negligence) and is followed by additional consequences of the reason (damage).

• 행사가 연기된 것은 날씨가 좋지 않았기 때문이었으며, 장소 변경도 고려되고 있습니다.

  The event was postponed because the weather was unfavorable, and a venue change is being considered.

  Here, '때문이었으며' is used to give the reason for the event's postponement (weather issues) and relates it to subsequent actions (venue consideration).

• 성적이 향상된 것은 그가 열심히 노력했기 때문이었으며, 선생님의 격려도 큰 도움이 되었습니다.

  The improvement in his grades was due to his hard effort, and the teacher's encouragement was also greatly helpful.

  In this sentence, '때문이었으며' provides the primary cause for improvement (effort) and associates it with additional supportive factors (encouragement).