According to testimonies collected to date, a total of ten such camps have operated since the foundation of the North Korean government. Currently, it is believed that five to six PPC are in operation in North Korea, frequently undergoing relocation, integration or division of the facilities. The total number of inmates in all PPC is estimated to be approximately 150,000 to 200,000. The number of North Koreans continuing to arrive in South Korea with some level of experience in detention at PPC is steadily increasing and their independent testimonies provide an important source of information needed for the objective and accurate study of human rights violations in PPC. The objective of this survey report is to present an overall and systematic analysis of PPC on the basis of in-depth interviews with North Korean witnesses in respect to the nature of human rights violation in PPC, the degree to which they are systematic, and the analysis and assessment of changes since the 1990s. 2. Comments on/ evaluation of earlier research studies Systematic studies that focus exclusively on PPC are not readily found in earlier Korean studies on North Korean human rights violations. Some studies of a limited nature on PPC were carried out by international human rights organizations. In Korea, however, the subject was only treated as part of an extensive review of the human rights situations in North Korea. Attempts have been made only in recent years for an exclusive study of PPC. The present survey will review earlier studies and examine information from the testimonies of North Korean defectors that have been increasing over the past decade. 10