I looked into this early this year. I called everyone I could think of in Australia, hassled anyone I had contact details for in Korea, searched the net and enlisted a friend living in Korea. And the result was that no-one knew.
The most useful thing I found was the web forum of the Korean customs department. Suprisingly this seems to be the main way they receive and answer questions.
However if I decided to do it I'd just turn up, preferably with a few phone numbers of people high up in the customs department, and see if I could talk my way through.
Vladivostok - Denmark 2008... Finished.
Denmark - South Africa 2010-2011... Finished.