yes~ hi - annyeong bye - annyeong or jal ga but for elderly person , hi - annyeong haseyo / bye - annyeonghi gaseyo

Oh yes, in informal situations (for instance, greetings between close friends), "an-nyeong" (안녕) can be expressed as both "hi!" and "bye! / see you!". This is something similiar to "salut" in Quebec region, "adiós" in Spanish (possibly in some Mexican regions), and "ciao" in Italian. So, take care, and 안녕! / Salut! / ¡Adiós! / Ciao! :)