Civilization V DLC - Korean Civilization & Scenario
This is the highly powerful science turtle civ, apart from that other one
Korea is one of the most powerful civilizations available, and with a great aesthetic too. It focuses on science generation, as you can see by Korea's unique abilities:
* +2 Science for all specialists and Great Person tile improvements
* Receive a tech boost each time a scientific building/Wonder is built in the Korean capital
It's quite fun to blow past everyone else's tech, have WWII submarines in the 1840s and maintain what is pretty much the world's best army, especially if it's not the largest. As such, it's best suited for building tall (small number of densely populated cities). The Turtle Boat and Hwach'a unique units help you with this, being powerful units meant for defensive purposes.
Korea's AI is supposedly peaceful and tolerant, with a focus on science and building tall. They're not guaranteed to stick to that, though - the first game I saw them in they didn't like me (because I was Babylon) and got dominated by Carthage.
Speaking of Babylon, they're the other powerful DLC science civ. They're more technical to play, but have a greater early science advantage - and early advantages can be very useful, even if Korea has slightly more overall science potential throughout the game. The purchase value of the Babylon DLC isn't quite as good since you only get the one civ, but if you want more science and potentially more interesting science, you'd do well to try them as well.
I haven't played the included scenario...yet.
If you want science, I'd recommend this.