I have found that people in Korea, though well-meaning, don't get it at all. My coworkers would constantly put bread, cookies, cakes, etc, on my desk, and then ask why I wasn't eating, even though I explained DOZENS of time! Once, at a BBQ place, my friend interrogated the owner about the meat and asked if it had any sauce on it. The owners repeatedly said "No, no, no," no sauce, but then once my friend dropped the phrase" severe allergy," suddenly the meat was magically soaked in wine! Then, halfway through the meal, I felt sick, so my friend asked once again, and the owner admitted that the meat had soy flour on it. *Bangs head against wall.* It's tough !
As far as having gluten free foods with you, I highly recommend iherb.com, a natural food and supplement website that ships all over the world. You could even go ahead and order so that you have a box of food waiting for you. Prices are really reasonable and shipping is dirt cheap. Good luck! I hope you enjoy your travels!