If you have lots of time - go to the RCC (it is straight ahead as you exit the people-mover at North terminal. Pay as you go bar, normally some decent snack options, more space. The SK Business lounge is very small, not much choice of anything and rather inattentive staff IMHO. Big advantage it is one level below boarding area in south terminal (mid-way between exit from people-mover and boarding area) where the SK flight departs. If you got to RCC give yourself at leat 15 minutes to get to the SK gate. Enjoy either way..