Excuse me. 실례합니다.
<when you make an attention from strangers>
Excuse me, is this the way to the cityhall?
실례합니다만, 이 길이 시청으로 가는 길입니까?
<when you want to pass thru>
Excuse me(could you let me through)?
실례지만 좀 지나가도 되겠습니까?
similar expression in above situation.
<when we want to go thru people in crowded place or so.>
저기, 잠시만요.
literally this means 'hey there, wait a minute' but we often say this, when we want to go thru people.
지나갈게요(지나갑니다)
please let me go thru you.
<when you need to leave the place or want to talk with other person>
‘Excuse me for a moment,' Wonjoo said and left the room.
'잠시만 실례하겠습니다'라고 말하며 원주는 방을 나갔다.
<when you did mistake. for example, you pushed people by accident>
죄송합니다(죄송해요). 미안합니다(미안해요)
oops, excuse me, I didn't know you are there. 죄송합니다, 거기 계신지 몰랐습니다(몰랐어요)
<when you couldn't understand or hear other person's saying>
Excuse me(pardon me)?
뭐라고 하셨습니까(뭐라고 하셨죠)?
cf. (please)say that again? 다시 한 번 말씀해주시겠습니까(말씀해주시겠어요? 말씀해 주실래요?)
<when you express oposite opinion to others politely>
Excuse me, but I don't think that is necessary.
죄송합니다만, 전 그게 필요하다고 생각하지 않습니다.
hope it could be helpful. have a great one.