on the occasion of; at the time of
on the occasion of; at the time of; when; during
開始に当たり、挨拶する。
Upon commencement, I will give a greeting.
発表に当たり、彼は緊張した。
At the time of the announcement, he was nervous.
卒業に当たり、感謝の言葉を述べた。
On the occasion of graduation, I expressed words of gratitude.