Looks like the Pepsi symbol to me. Lol. Yes brand advertising has gone too far. Instead of one racing car, Pepsi now sponsors a whole air force.
But I can see where this would increase morale. Just imagine the tired and hot and thirsty ROK troops on the ground look up in the sky and see one of their planes fly by, then they will be reminded of a cool refreshing ice cold can of Pepsi.
But I can see why they would rip off the US symbols, since isn't SK military doctrince basicly handed down to them by the US, and didn't the US practicly raise up and retrain the SK army from the ground up after the war in order for better coordination.