I can't tell if you're just trolling or actually care. Either way it's fairly dickish behavior that's totally unnecessary and doesn't advance the discussion.
Calling someone by their chosen name is one of the most human things you can do. Dale Carnegie and all that. The United State's dehumanization of the citizens of the DRPK begins with calling them by the name we prefer rather than the name they've chosen for themselves.
(It's also not U.S.- or English-specific; you do the same thing in all these cases in Danish. Except for formal documents, it's Nordkorea and Sydkorea, not Den Demokratiske Folkerepublik Korea / DDFK or Republikken Korea / RK.)
Anyway, words are hard.
EDIT: Also, we call it "Nordkorea" in Sweden. Take that, Kim!
The nation is neither democratic, nor is it for "the people", nor is it a republic - but instead a totalitarian dictatorship run for the convenience of one man and his favored associates. But it is Korean. One out of four isn't too bad, I guess.