When taking a vacation from a hagwon (an after school private academy) sometimes it is necessary to find your own replacement. Normally, employees at my company are not responsible in any way for finding their substitutes, but luck fell upon me to find my own. The best thing I found was to take to Facebook.
Substitute Teaching Groups
There are a few groups on Facebook filled with people looking to hire, and work as, substitute teachers. A few of the ones that worked the best for me were Substitute Teachers In Korea, and Sub In Seoul if you’re lucky enough to be in the Seoul area.
Location Based Groups
Make sure to check these – especially if you’re in a small city far away from anything else. You’re much more likely to find someone who’s already in your city who might not have that much experience, than an experienced substitute who’d be willing to travel the distance. Just search around and you’re bound to find plenty – they will have names like “Jobs in X City” or “X City Job Board”.