US KH-11 intelligence satellites can just as well clearly show those in there who are in the 'anti-revolutionary' segment of the DPRK population, being prepared for firing squads (usually three AK-47 shots and then dumped into a shallow grave, with fellower prisoners as witnesses).
Regarding DPRK society, every North Korean right down to an infant is labeled as a member of one of three categories as far as the Korean Worker's Party is concerned: Cadres (or trusted), workers (not necessarily trusted), and traiterous anti-revolutionaries (the majority of the population.) The most suspect of the third category are regularly taken away for "relocation" or "internal immigration." Each of these camps has a geographic name or a code number name (like "Camp 11 in Hamkyong Province", etc.)
Escapees from these camps have written blood curdling accounts in the Japanese and S. Korean press and books. Some have, from memories, drawn maps and cartoons of what goes on there.
It is not for the faint I can assure you.
They suffer as I write.