grandfather:할아버지 ha ra bu ji
grandmother:할머니 hal mu ni
father: (formal) 아버지 a bu ji (informal) 아빠 appa
mother: (formal) 어머니 u mu ni (informal) 엄마 umma
older brother:
from a girl: 오빠 oppa
from a boy: 형 hyung
older sister:
from a girl: 언니 unni
from a boy: 누나 nuna...