Korean short ribs are usually cut 1/4" or 1/2" thin. Cut 1/4" thin, they will grill faster, be more tender, and have the marinade penetrate more fully. The tradeoff is that they fall apart more than the 1/2" thick ribs. For beautiful presentation, choose thicker ribs. For succulent, more tender ribs, go with the thinner option (but expect some of them to fall off the bone before they hit the plate).