不在中
during my absence - 斎藤和英大辞典
不在中
(不在の時に重きをおけば)while one is absent―during his absence―(不在なることに重きをおけば)―when one is absent―in one's absence - 斎藤和英大辞典
旅行中で不在です
He is away on a journey. - 斎藤和英大辞典
http://ejje.weblio.jp/sentence/content/%E4%B8%8D%E5%9C%A8%E4%B8%AD