It's not quite a marathon, but here's the scoop...
www.ygmarathon.net. It's all in Korean, so you may need help translating. I used translate.google.com which gave me a general idea of what was said.
This is a 5K, 10K and 1/2 marathon scheduled for May 25 at 9am. It is a chip timed race. It will start from the Yeonggwang Sportium (stadium). They give you a T-shirts in sizes s, m, l, xl, 2xl and 3 xl. The cost is 10,000 won for the 5K, 25,000 for the 10K and 30,000 for the half. Deadline to enter is April 25. You can call 1566-1936. There is a man that speaks English and can sign you up. Their bank is NongHyup and the acct # is 664-01-003295. And of course photos are available online after the race sometime....