North Korean Intellectuals

I was intrigued to read in Hagen Koo's book "State and Society in Contemporary Korea" that unlike Mao Zedong, Kim II Sung has rarely, if ever, denigrated intellectuals and experts. Kim also explicitly authorized their widespread introduction into positions of authority.

This made me wondered, how come the North Korean intellectuals never spoke their minds the way Chinese intellectuals did? Or maybe they did but were sidelined? Or maybe they were further induced and "sold" into the system? But surely there must have been intellectuals with personal convictions that differed from the official line?