I completely understand people not being happy about the fairly blatant racism in Korea but you have to keep it in perspective and be careful not to make a blanket assumption every Korean is like that because they're not. Also, EVERY country has it's own prejudices of some form to a greater or lesser degree. The fact it is more transparent in Korea (and plenty of other countries) isn't nice but you know where you stand. In most western countries it is still there but just suppressed through political correctness and fear of litigation, so you face prejudice without it being visible. To me this is worse in some ways. If you're applying for a job and get refused for some bogus reason when you know it's because someone doesn't like your skin colour or religion or whatever, is that any better than the blunt truth? Some people just look for a reason to be offended because they've been conditioned to think that way these days and it kills a lot of conversations that might provide a chance to change peoples thinking. Don't get me wrong I don't condone racism at all and don't understand the mentality behind it at all. It just seems an irrational fear of something different, and I think that's part of the issue in Korea where conformity is normality, probably because of the strong confucian influence, even amongst the Christians and Bhudists. People react quite negatively to any deviation from mainstream society in Korea and this seems quite deeply rooted in their culture. although it is fast changing like everything in Korea. And that pace of change is another element. People are working such long hours there thanks to the remnants of Japanese influence over 40 years of occupation, that they simply don't have time to be polite. I guess the key is to observe with an open mind and be aware of your own prejudices and pre-conceptions.
I have been married to a Korean quite a few years now and have visited Korea many times so I'm close enough to this issue to understand it a bit. I also know teachers who work there and have heard their experiences. Most of them are no where near as judgemental as the comments on this blog. They accept they're in a different country and so accept you're playing by someones elses rules even if you don't like them. As a white man I haven't experienced the sort of racism that black people and south Asians experience in Korea of course and I feel sad that they have to face this in Korea or the U.S. or anywhere else. They face this every day of their lives while I might face it a few times a year at worst so you can't compare that experience. But everyone knows what it is and should be able to empathise. Those that can't or won't empathise are the ones that make all the noise and love to foster hatred. These people are mentally ill and need help as far as I'm concerned.
Look for some of the positives in Korea if you can, there is plenty.