I tried linking to the below picture rather than downloading and uploading it again. The result is, it is full size, although only half can be seen on this page. After you have read the article thoroughly, you have my permission to click the map to see it in it's entirety.
The festival takes place at Seorak National Park. This is the fifth annual and I have not attended one, but have always wanted to. I hope to do the 20km course although if I am dragging a rugrat (always the loving father), I will do the 5 km course. The website is here.
The 20 km course is only on Saturday, which also has three 10 km courses and a 5 km course. Sunday has only the 5 km and 10 km courses.