Thank you in Korea?

There are a few ways. They're really the same. However, in Korea, there are two ways to say things normally. The "formal" way and the "informal" way. The "formal" way is used for adults and important people, and the "informal" way is used for people younger than you or friends. I will tell you both ways.

FORMAL WAY:
감사합니다. (gam-sa-ham-ni-da)
고맙습니다. (go-map-sim-ni-da)

INFORMAL WAY:
고마워. (go-ma-wo)
안녕. (an-young)

I hope I have been some help!