Changing visa from H-1(working holiday) to student or working visa

Hello,

I am going to South Korea on an H-1 visa for 18 months in September. In the event that I decide that I want to study at a Korean University, or that I'm offered a job opportunity within this period of time, is it possible to change my H-1 visa to a student or working visa? Even if I have to come back to America for a visa run, that's fine; I just want to know if it's possible to get a switch. While I'm excited to go to Korea on a Working Holiday, 18 months is a long time, so I want to be open to other opportunities that may arise during my stay. 

I've been tearing the web apart trying to find an answer to this question but I've been unsuccessful. If anyone could help me out, I would be eternally grateful!

Thank you