I called them for this issue, they say they accept non-Korean members but there is a problem with the SMS system.
I asked further but the person said I couldn't make an account now and wait for the problem to be fixed, BS if you ask me.
Why is it BS? Are you in tantrum mode again? They told you there is a problem with their SMS system and to wait for the problem to be fixed. What is wrong or abnormal about a Korean (or any other) exchange having such issues? If you live in a perfect world, then there is a lot to learn and catch up with outside that world you live in.
The exchange is in Korea and therefore caters primarily to users in that jurisdiction. If you live elsewhere and hope to use this exchange's services, they are not obliged to offer that service and if they do, it wouldn't be "BS" if there are issues here and there. It could be a very real SMS systems issue. It could also be a precautionary or preemptive issue as a result of recent hacking problems affecting Korean exchanges.
http://on.wsj.com/2kQQdN4No need to throw a tantrum over a system glitch. Wait for them to fix it or look for alternatives.