For the Kubuntu people wondering if they can replace .gnomerc with .kderc -- in my experience that doesn't work.
For Kubuntu I do the following (circa 10.10 Maverick):
1. Copy Batang, Dotum, and Gulim fonts from Korean windows install to /usr/share/fonts/windows-fonts (create the windows-fonts directory). Run fc-cache to refresh the font cache. You could probably also download these fonts from the interwebs.
2. Install the nabi package via your favored method. I prefer the trusty: sudo apt-get install nabi
3. Now instead of modifying/creating .kderc you should create a script in ~/.kde/env called something like nabi.sh with the following:
chmod +x nabi.sh and restart kdm and X.
You might have to fool around with the dpkg-reconfigure locales, but I think simply specifying a UTF-8 based locale is good enough. Hope that clears up any confusion. If I put the contents of nabi.sh into .kderc then nabi would go to the system try but I would not be able change into hangul.