Is there an active developer forum in Korea?

Besides Oki who replied above...

Living coding: https://www.facebook.com/groups/codingeverybody/

Android Pub: http://www.androidpub.com/

GDG Korea Android : https://www.facebook.com/groups/gdg.korea.android/

GDG Seoul : https://www.facebook.com/groups/gdgseoul/

Devpia: http://www.devpia.com/

I think there's about this much more.

Representatively, http://okky.kr/ is this site

Other than that, there are more places that are gathered by language or field

https://www.facebook.com/groups/pythonkorea/ Python Korea

http://semog.co.kr Triangle Paper

I have Debs Note. https://devsnote.com

If you post a question, you answer it well and there are various information.