There are several websites that may help you in broadening your friendship circle in Korea.
1) Meetup - www.meetup.com. This website has many different groups that organise events in various cities around the world, and it is excellent in making new friends. Just join a group that you find interesting, and attend a meet up.
2) Facebook - Of cause FB is great as a way to stay in contact with friends and family back in South Africa, however, there are also groups and societies on there, such as Saffas in Korea and others, that may or may not organize meet ups and events in Korea for South Africans:
Saffas in Korea (http://www.facebook.com/group.php?gid=127544466273).
South Africans in South Korea - General stuff, you can ask questions or just say hi and what not. http://www.facebook.com/#!/group.php?gid=2309967428
Sakornet - they often organize some big events (and braai's) for Saffas in Korea