This is Zooladies husband.

I was hiking in South Korea and saw a snake a bunch of times and was wondering what kind it was. She told me this was the place to ask. It was about a foot and a half long (average diameter for that length). It was green, but every 3 to 4 inches it had thin yellow and black bands. It had a thin, sleek head. And I guess that's about it as I didn't get too close. Anyone have an idea?