This link is to a very poor (but entertaining) Bing translation of a Korean article that just showed up in my news feed. It's the only source I could find unfortunately. The gist is that Yoon, who is 27 and profiles as a back-end starter, is heading to LA to meet with his agent, Scott Boras in preparation for a move to MLB. He has reached full free agency in the KBO, so won't require a posting fee to negotiate with. If NPB's Masahiro Tanaka doesn't get posted, which is quite possible, Yoon would be the best available pitcher on the international FA market.