Addressing friend's name
When a person is addressed 아/야 is attached to their name. If my name were 진우[Jin-u], my friend would call me, 진우야! [Jin-u-ya]. This is like "Hey 진우/Jin-u!"
This colloquialism should only be used between close friends. This is an informal expression. At school, friends call each other this way, and teachers to students but not vice versa.
Note that 야 is used for names without a final consonant and 아 for names with a final consonant.
- 진욱 → 진욱아!
- 진우 → 진우야!
- 영희 → 영희야!
- 철수 → 철수야!
- 경일 → 경일아!
So when you call your Korean friend's name, just add 아/야 to their name.