Congrats on your new assignment.
I've been in Korea for about 8 years now. Yes, there is diving over here (we even have a little club with a boat), but be advised, the diving is not 5 star and you need to be careful who you dive with.
Korea has a seperate organization called "korean underwater diving association-KUDA" and they are not recognized by anyone. Most Korean divers do it for the purpose of hunting. Their training is very poor, and their dive habits are on the verge of being extremely unsafe. Personally I rarely dive over here. I have this fear of being speared by my "dive buddy."
I make monthly trips to Thailand, Phillipines, etc... You can fly to any of these places (over your government 4-day weekends) for less than $350. A nice four day dive trip to Southeast Asia will run you about $600 for airfare, hotel, diving, and food (plus, if you're single, there are always "friends" to be made.
We're doing a 5 day trip to Cambodia this month (see my post in the travel section).
You can dive here, but be careful, get in touch when you get here and you can dive with us.