I'm not sure what is "아체, 슬체". I tried to find them on google.
I found "아체슬체 패키지" on kartrider site(kind of racing game like mario kart).
It's an item change&slot change package in game.
I think it come from item(아) change(체)&slot(슬) change(체). (아이템 체인지&슬롯 체인지.)
Also that's shortened word.