If you don't know already, there is a FREE travel helpline for foreigners in Korea (in English, Chinese, and Japanese).
(Area code) + 1330
They can give you information from bus timetables to Mexican restaurant locations nearby, and in my experience they are generally on - or very close to - the money.
You MUST dial the local area code (02 for Seoul, 054 for Gyeongbuk, etc.) + 1330.
If you're dial the wrong area code, they won't be able to help you. If you're in Seoul and call 052-1330, they will tell you to hang up and call the Seoul extension.
Korea area codesSeoul 02