Turns out it's a
K1. If it's a K1A1, it even has the 120MM smoothbore of the M1A1 and Chobham armor. Diesel, not turbine powered. No longer in production. It's about to be replaced by the
K2, which has 300 more HP, among other things.
Given that Korea is pretty much the world's shipyard these days, and that they have unpleasant neighbors to the north, it's not surprising that they're using that steel mill and foundry capacity to grow a domestic arms industry, rather than just buy a few toys for parades.
Korean industrial economic policy has generally mimicked the Japanese policy with about a 20 year lag, and the Japanese pretty much have rolled their own anything since about 1970 or so, so it's not too surprising that Korea has been building its own MBTs since 1988. With the way the Chinese have been behaving lately, expect the ROK Navy to put on some muscle soon, as well.