I've studied Japanese politics and society, and many people comment on how difficult it is to be a foreigner in Japan, working or living. I think it's interesting that there seems to be a comparably difficult situation for foreigners in Korea, as described in this Chosun Ilbo report. The report focuses on financial and business related difficulties, such as problems getting a cell phone plan or internet without a Korean to sign you up for it, but it seems indicative of the kind of insularity that Japan is often accused of.
I would also imagine that reactions like these are rooted in negative reactions to foreigners on their soil previously, like the Japanese, specifically. Is that an accurate assessment? Is there a controversy regarding immigration policy in Korea as there is in the US?