The number of South Koreans studying in China more than doubled to 62,855 in 2012 from 2003, according to South Korea’s Ministry of Education. The number of U.S.-bound students grew 50 percent to 73,351 in the same period.
Perhaps this has something to do with it:
Trade with China climbed an average 20 percent per year between 1992 and 2012, faster than the 6 percent growth with the U.S., according to Korea Customs Service. South Korea exported more to China than to the U.S. and European Union combined last year. China overtook the U.S. for South Korean foreign direct investment in the first quarter, the finance ministry said.
There is more here, and for the pointer I thank KunLung Wu.