안녕히 = annyeonghi (peacefully)
안녕히 게십시오 = annyeonghi kesipssio (goodbye)
*This greetings is use when we as the owner of the house greets goodbye to our guest @
안녕히 가십시오 = annyeonghi kasipssio (goodbye)
*This greetings is use when say goodbye to people outside of the house. For an example at the restaurant.