Ok, here's my questions:

1. The school years are four or three? Because in America they have 4 years and elsewhere they have 3 years.

2. In Korea they usually have 3 years?

3. I know in American movies they have seniors, juniors, sophomores and freshmen. Is it for high school and university or just for one of them? Does it work the same in Korea?

This is important for my school related fics, so I'd appreciate it if you can tell me. Thanks for reading!!!!!