I've seen that  when it comes to OCs most people in here go for what they remember best, and sounds most american as possible aka. Kim or Park or Lee. Accompanied with Hana/Minah/etc.

They're possible names, and there's nothing wrong with them, but if you're dedicated enough you might want your OC to be unique and realistic, and the first step to make it happen is by a thought-out, proper name.

So in order for you to not be limited in options and not loose yourself in the internet and data. I'm listing them from most to least common.

Shall you know about korean surnames, they're ordered in "families" so there are not that much BUT all of the have from five to even twelve variants. So I have only chosen the ones that are most memorable, easy to pronounce, and phonetically appealing for non-native speakers. 

I did this for myself but decided to share it here since I don't have a blog or a personal page. Note: I'll put an astherisc (*) for my persoanl favourites.