The Joongang has an article about ski hills, mostly in Gangwon, that offers plenty of detail.
Currently, there are 16 ski resorts in South Korea, with the number of fans of skiing and snowboarding rising annually.
Those craving a world-class experience should try Yongpyong Ski Resort in Pyeongchang County, Gangwon Province, which is once again trying to host the Winter Olympic Games. Nearby Phoenix Park ski resort is known for its spectacular scenery. You can reach High1 Resort in Jeongseon County, Gangwon Province by train, and if you want to stay closer to Seoul then Konjiam Resort in Gwangju County, Gyeonggi Province is the way to go.
[High1] Staff members dress up and entertain skiers waiting to board the gondolas with magic shows, pop quiz games and raffles.
I have not been to High1, but they do a lot of do a lot of advertising and promotions in Sokcho.
Read the article for more details.