Probably one of the best ways to travel in Korea is by train. There are several different classes of trains one can choose from, but if you’re a commuter, chances are one you might elect to ride is the Nooriro (누리로).
The Nooriro is a newer train, essentially a glorified subway. It is nicer than a subway and can travel at speeds up to 150kph. It’s also electrical rather than diesel powered.
I’ve had the opportunity to ride nooriro trains a few times and have found them a better ride then their slower counterparts.