Check this link out. Its a how to on clearing your corners. When I did it, it was done on my 04 Optima I once had but if you read it you will get the general idea on how to do it and how long to bake them for. In the spring Im going to be doing this to my Spectra.
http://www.kia-forums.com/do-yourself/28141-clearing-corners-optima.html