Buchae Rock has two faces: the N face is primarily trad (a few bolts and anchors on most routes) and has about 15 routes; the S face has about 11 sport climbs. The ridgeline is a scramble, and will allow you to TR most of the routes.
It can get windy and cold on the mountain, but you can also find some sunny climbs on mild winter days. While the main trails get crowded, the crag is accessed by a climbers trail and is fairly secluded.
Geumjeongsan is a small mountain in the middle of Busan, Korea's 2nd largest city. Buchae Rock is one of the 2 "main" developed crags. From Oncheonjang Subway Station (homeplus) you can get a bus up the mountain. Get off at the top and follow the trail -- you'll see the rock as you get close, with it's boulders balanced on top.