I am getting mixed info on the bus in Wonju. I have read: catch bus #52 at the Fam-Mart bus stop next to Wonju train station (I am familiar with the stop as I live nearby Wonju). In this thread I have also read that you can catch bus #52 on the opposite side of the large street in front of the Wonju Express bus terminal (also familiar to me.)
A few Korean websites (featuring vague information in their English versions) suggest that bus #54 in Wonju also goes to Ganhyeon. (I don't feel this holds water, a few buses familiar to me in Wonju seemed to change course over the summer, so I am skeptical.)
BUT, anyways... I will be in Wonju tomorrow near the express bus terminal... I will check the #52 route there the best I can. I will report back, however I imagine the bulk of the people coming will figure it out on their own. Worst case scenario ask the driver with your Korean skills!