there are pairs to use these are what I am thinking when other Koreans say those words. 오전 오후 : 오전 means before 12 in the morning. 오후 means after 12 (at noon) 아침 점심 저녁 밤 : 아침 means "morning", 점심 means around 12, 저녁 means "evening", 밤 means after 9 (21:00)? So...in total, it looks like, 새벽(dawn) -> 아침 -> 오전 -> 점심 -> 오후 -> 저녁 -> 밤 -> 자정(midnight)

by the way, did you mean "모으다"? we use 모으다 when someone is gathering something. (나는 우표를 모으고 있다.) 모이다 is a passive form of 모으다. (사람들이 모이고 있다. 사람들이 모였다.)