Application for tourist visa in Vietnam

I have resigned from my university in Seoul in that I have retired. My E-1 visa expires at the end of February and I am off to visit Vietnam for a few months, and also in hopes of visiting China. Since my E-1 Korean visa and ARC expire 02-28, am I able to apply within Korea as a Canadian citizen? If I am not able to do this in Seoul, am I able to apply for a visa for China while in Vietnam?