Korean instructors I know use 뒤로돌아 for turn around."Fix your uniform" would be something like 도복정리, although I don't know if Korean classes say it at all. I don't know if they say 뒤로돌아 either, as it's informal and such commands would be said in noun form and not imperative. For kneel, it would probably be 무릅! or 무릅꿇어.
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