I have found seven identical facilities around the country wich are actually chicken farms (닭공장). You can see one of them in this video from the Central News Agency.
I just found what looks like some curtains array antenna at 40°04’46.03″ N 126°06’42.21″ E.
I found some buildings around the country wich seems to be restricted by fence and guard towers. Maybe they are just military barracks or some storage buildings but I still want to share it. So below there some pictures of them with personal analysis (wich could be wrong). I have also read some testimonies of Korean refugees in “The Hidden Gulag Second Edition” by David Hawk but I don’t find anything about it. So if you have any idea of there purpose let me know.
Some Google Earth files: