It's been about 2 years since South Korea started using the standardized chargers. It's now expected that most internet cafes (PC bangs we call them here) supply chargers at each terminal. As the parent said, convenience stores have booths for paid charging.
The charging booths in convenience stores have been around for a long time, actually. The three major cell phone companies here (LG, SK, and KTF) have used unified chargers for their own brands for a much longer time, so it wasn't uncommon even 5 years ago to see 3-6 charging booths in stores.