Economy of North Korea
Estimating gross national product in North Korea is a difficult task because of a dearth of economic data and the problem of choosing an appropriate rate of exchange for the North Korean won, the nonconvertible North Korean currency. The South Korean government's estimate placed North Korea's GNP in 1991 at US$22.9 billion, or US$1,038 per capita. In contrast, South Korea posted US$237.9 billion of GNP and a per capita income of US$5,569 in 1991. North Korea's GNP in 1991 showed a 5.2% decline from 1989, and preliminary indications were that the decline would continue. South Korea's GNP, by contrast, expanded by 9.3% and 8.4%, respectively, in 1990 and 1991.
Juche
In 1956, Kim Il-sung declared "Juche" to be the guiding principle of the economy. After the devastation of the Korean War, North Korea began to rebuild its economy with a base in heavy industry, with the aim of becoming as self-sufficient as possible. As a result, North Korea developed what has been called the "most autarkic industrial economy in the world". North Korea received a lot of economic aid and technical assistance from the Soviet Union and China, but it did not join Comecon, the Communist common market. In the 1990s, it had one of the world's lowest rates for dependence on petroleum, using hydroelectric power and coal instead of imported oil. Its textile industry uses vinylon, known as the ""Juche" fiber", which was invented by a Korean and which is made from locally available coal and limestone. The history of the development of vinylon often featured in propaganda that preached the virtues of technological self-reliance. North Korea had 10,000 CNC machines in 2010. The first domestic homemade CNC machine was introduced in 1995 and in 2017 it has around 15,000 machines.