There are not many ways to say these greetings in Korean, since everyone just says "Hi" all day long. I will do my best to find some phrases for you though, haha. Good morning - Formal: 좋은 아침입니다/좋은 오후에요. - Informal: 안녕! or 좋은 아침! Good afternoon Just saying 안녕 will be okay, but if you really want to say good afternoon.... - Formal: 좋은 오후입니다/좋은 오후에요. - Informal: 안녕! Good evening/Good night - Formal: 좋은 밤입니다/좋은 밤이에요. - Informal: you know where this is going... 안녕! I hoep it helps :)