Wikipedia
North Korea's political penal labour colonies, transliterated kwalliso or kwan-li-so, constitute one of three forms of political imprisonment in the country, the other two being what Hawk (2012) which is translated as "short-term detention/forced-labor centers" and "long-term prison labor camps" for misdemeanour and felony offences respectively. In total, there are an estimated 80,000 to 120,000 political prisoners.
In contrast to these other systems, the condemned are sent there without any form of judicial process as are their immediate three generations of family members in a form of sippenhaft. Durations of imprisonment are variable, however, many are condemned to labour for life. Forced labour duties within kwalliso typically include forced labour in mines (known examples including coal, gold and iron ore), tree felling, timber cutting or agricultural duties. Furthermore, camps contain state run prison farms, furniture manufacturing etc.
Estimates suggest that at the start of 2007, a total of six kwalliso camps were operating within the country. Despite fourteen kwalliso camps originally operating within North Korea, these later merged or were closed following reallocation of prisoners.