I don't know the name of this tune, but you've probably heard it. It's not to hard to figure out. I made this song to go with Lesson 5.5
Oh where oh where is Namdaemun?
Namdaemun?
Namdaemun?
Where oh where is Namdaemun?
Namdaemun, Please?
Turn LEFT
and Go STRAIGHT
Turn RIGHT
AT THE BANK
Where oh where is Namdaemun,
Namdaemun?
Namdaemun?
Where oh where is Namdaemun?
Namdaemun, Please?
Turn LEFT
and Go STRAIGHT
Turn RIGHT
AT THE BANK
Where oh where is Namdaemun,
Namdemun, Please!

But it's still part of the GEPIK curriculum.
It's a little harder to find it these days.