Usage patterns
〈人〉がゼミに入るfor someone to join a seminar (research group)
He joined an economics seminar.
ゼミで発表するto give a presentation in a seminar
I'll present about my paper at next week's seminar.
ゼミを取るto take (enroll in) a seminar course
I'm taking a history seminar this semester.
ゼミの合宿a seminar's off-campus retreat/camp
During summer break, we went to a hot spring town for our seminar's retreat.