To be correct it should be Russian. The Koreans and Chinese didn't start making sks until after the Korean War.
To be really correct it would be an earlier Russian SKS. The Korean War was Jun 25, 1950 – Jul 27, 1953
Given how "new" the sks was in regular Russian production there has been talk about how it would be unlikely the North Korean army would be issued them. However Russian advisors may have been in county with them.
Judging by the gas block it looks like a 1950 Russian.