Since said hello and exchanged business cards at once with a lot of people yesterday, I do not remember the name.
Sorry, could you let me know who is which person?

어제 많은 사람들과 한꺼번에 명함을 주고 받으며 인사를 하여 저는 성함을 전혀 기억하지 못하고 있습니다.
죄송하지만 누가 누구인지 알려주시면 안 될까요? 聼起來自然嗎?

**Since I said hello and exchanged cards with a lot of people yesterday, I do not remember all of their names. Sorry, but please could you tell me who each person is?

I think this might be what you're trying to say, I'm not sure though because I don't speak Korean :)