My friend who's lived in Korea a while says if you want a very "safe" choice, you might pick something like Monsieur Han (probably Mr. Han in English) by Hwang Sok-Yong, as it's widely recognized as one of the "must-read" of contemporary korean literature, both at home and abroad. He's liked "L'Invité" (by the same writer too.

He says the translations read very nicely, but he's referring to the French ones.

He also likes Jo Kyung-Ran a lot (especially a novel about a woman chef that he found quite deligthful), and Yy Ch’Ongjun

In a general way he says you can more or less take for granted that the few writers available in translation are pretty much the big names of contemporary literature and for the most part their best works, so whatever cover blurb catches your interest is probably the best guide, and perhaps to avoid what sounds a bit too weird/ too "out there" unless a culture shock/novel you won't really understand is precisely what you seek (though Thom says that aspect isn't as bad as with some Japanese novelists).