FWIW, I see the people answering by translating it literally. However; I never, ever hear that used as a greeting. 아침 does mean morning, but it also means "Breakfast." :). Someone may ask if you've had breakfast as a morning greeting. Normally, people use the greetings you learn in Korean without respect for time of day. However; upon parting a business, or getting out of a cab in the morning, I sometimes say (and sometimes hear my wife and relatives say) 좋은 하루 듸세요, which is telling someone to have a good day. That's as close as I get to the western greetings like "good morning." But note that was used when parting, too :). It'd be good to hear from a few natives when they pause long enough to think if it is normal, but from my observations, time of day greetings like "good morning" or "good evening" aren't used.