wow.. some of the expressions are just too polite and awkward for me. maybe you want to say it to the... mr. president? :D tom actually has transliterated the meanings, but let me add some annotations. 안녕히 주무세요~ it's literally translated as "bye and sleep tight". for a more casual meaning it's equivalent with "good night". youngsters usually use more casual salutation like "잘 자요" or "잘 자" ㅋㅋㅋ as pointed by tom, it's the sound of chuckles. other variants are 허허 (hoho) and 헤헤(hehe) 다음에 뵙시다 perfectly means "see you later" but people say "다음에 만나요" or "다음에 봐요" more often 좋은 꿈 꾸세요 in colloquial meaning, it's something like "have a nice dream" (actually it's the same with tom's but for the sake of diverging the answer, here is another wrap-up.. :P)

안녕히 주무세요（对长辈或老师说的敬体【晚安】） 다음에 뵙시다（敬体【（下次）再见】） 좋은 꿈 꾸세요 （对平辈【做个好梦】）

안녕히 주무세요~ (Good night) ㅋㅋㅋ (ㅋ pronounce 'ke', it looks like sound when you chuckle.) 다음에 뵙시다 (See you later) 좋은 꿈 꾸세요 (Have a good dream)

【세요】本身不算敬体，但【주무시다】是【자다】的敬体，【ㅂ시다/읍시다】也是敬体。