Default [Q] Noob Stuck in South Korea

I am using a Sprint model LG G2 LG-LS980 - Sprint Customer service unlocked my phone and I did the UICC unlock process succssefuuly in settings. I went to the LGU+ store here at the Army post and they were able to get my phone to talk and text but could not get the data unlocked. Can someone help me out what do I need to do to get this phone working on a South Korea service provider!

Thanks a lot for all you folks do to support us overseas!!