Where did you get those numbers from? Didn't see them in the article you posted.
While I don't doubt that number is disproportionately high with the US army presence in Korea, internally I guarantee the numbers are not accurate.
Korean society is extremely patriarchal and protective of all of their boys. I've been living here for two years and have heard many stories about how police officers telling women that they shouldn't have taken free drinks from guys, and because they accepted it it's their fault they were raped. Guys escaping charges in exchange for starting their military service ASAP. Actually quite recently a judge threw out a rape case claiming the victim was giving mixed signals because she offered the guy the food she couldn't finish.
On top of that the standard rape charges are lowered if you were drunk, and lowered further if you were too drunk to remember. This is the same for peodo crimes as well. The country is pretty fucked when it cones to protecting their daughters from their own sons. This isn't to defend white dudes, all should be held accountable.