Just see her a few more times and keep escalating after building a bit more comfort with her.
DO NOT ask her why she doesn't want to do X or Y. The best way to find out if she wants to is to DO it. A lot of times she may resist initially, but often because she doesn't want to appear too easy. If you react badly to her initial resistance and start pouting and moaning and asking her why, then that's a real attraction killer and you may lose the opportunity to try again. If you don't react, leave it a while, and then try again, chances are she may well comply after 2 or 3 tries. I've had a girl reject a kiss 2 or 3 times, and say "I'm not sleeping with you" 4 or 5 times before eventually doing it! "No" often means "maybe, later."
As for her being Korean, it's true that Asian/Oriental cultures tend to be more conservative and thus you may have to calibrate things by moving slower and building more comfort with her.
Also, step back from the situation a bit. She doesn't even speak that good English - how much do you really have in common with this girl? What do you guys even really talk about? She can't really mean THAT much to you, therefore go into your interactions with her like a GAME or an experiment in escalation - see if you can figure out what makes her tick and what you need to do to make her feel comfortable. It'll be a useful learning exercise for future conquests!
Good luck
