Banking: The single biggest problem for non-Korean citizens living in Korea is banking. You cannot just open an account at Kookmin Bank (KB) and then take your ATM card to the U.S. and withdraw money at the Citibank ATM in Los Angeles. It doesn’t work.
I must recommend KEB, Korea Exchange Bank, which has a global banking account, where foreigners can open accounts, which have the same online banking capabilities as the other banks in Korea. In addition, with the global banking account, you can with withdraw money when you are back home (assuming that is not Korea).
VITAL POINT: You need to designate a foreign exchange bank with a form at KEB. Without this, you will not be able to withdraw money in a country outside of Korea, even if you have the correct acccount, and ATM card. This is a VITAL POINT (the phrase native Koreans love is “key point”). I cannot stress how important this is!.