I am sure they did. I heard once that the reason N. Korea had been keen on sending their troops or military advisers to many third world conflict zone (in small numbers, though,) is that they feared their troops would lack real combat experience which SK troops were getting in Vietnam. On the order of tens of thousands of troops.
My cousin was in Chu Lai and the GIs and Marines shared a bar with the ROKs. He saw a ROK from the Tiger get into it with a Marine over a Bgirl. The guy hit the Marine 3 times and the Marine stopped breathing. The ROK’s CO came storming in. They took the ROK out and the MPs told my cousin that the ROK officer put one round in the back of the guy’s head.Very tough hombres.