Credit Cards Accepted in Korea?

Hi all! I'm planning a trip to Seoul (my first international solo trip - so excited!), and I'm wondering what experience you have had with your credit cards being accepted / rejected? I've read some stories of people's cards being rejected, so I'm hoping to learn and not make mistakes, since I'm also getting my first travel rewards credit card. (AmexGold or the Capital One Venture X, both with no foreign currency fees.)

EDIT: I realize the title is confusing! I understand of course credit cards are accepted - I meant which ones specifically. Sorry all!