If you've been dying for climbing material to read or watch in English, here is the beta on such a store:
서울시 성북구 동소문동1가 44 삼우빌딩 502호. (우)136-031
(Seoul-si Seongbok-gu Dongsomundong 1ga 44 Sam-u Building 502ho)
In order to view a map of his shop, click on "회사소개" in the upper lefthand corner of his homepage.
The owner's name is Ho, Gyeong-pil. His shop is completely dedicated to climbing and mountaineering. He has a ton of books, magazines(current and old) and videos both in Korean and in English.
You can also have him mail order you whatever it is you find of interest on his webpage if you live too far away or cannot make the trip.
If you have difficulty finding his shop, feel free to give him a call. I'm sure he'll be glad to come out to meet you nearby.