North Korean development model has been primarily characterized by plan economy in ``Yuil`` regime. In this model, the economy is captured by the political, and the management of economy is directly leaded by political party. Because the material incentive is very restricted in North Korea, labour mobilization is mainly achieved by ideological penetration. The main strategies of North Korean model have been threefold: 1) priority on heavy industry. 2) emphasis on self-supporting national economy. 3) advances on the military and the economy side by side. The dynamics of North Korean economy has determined by these characters of its development model and strategies. After Korean war. North Korean economy was rapidly grown for the following two decades. In the 1970s, however, the North Korean economy has been stagnant. In the 1990s, the economic situation has been worse and worse, and North Korea has finally confronted to serious economic crisis. At the early stage of North Korean development model. economic growth by extensive accumulation was possible due to the plan economy. which was directed by the powerful government. Like in other existed socialist countries. however, its economy has been gradually stagnant. In this regard. the problems of North Korean economy is deeply rooted in the intrinsic contradictions of existed socialist development model. However, economic crisis of North Korea in the 1990s, is partly caused by the changes of external circumstances -namely the end of Cold War and the emergence of small cold war around northeast Asia. The changes of international circumstances around the 1990s have made a severe impact on North Korean economy. The trade between North Korea and other existed socialist countries has dropped abruptly. while the relations between North Korea and capitalist countries has not expanded. In this situation, the North Korean development model has paralyzed. Such external circumstances have forced North Korea to change its development model in relation to external opening and internal reforms, at least partly. In fact, North Korean development model have sought external opening since the beginning of the 1970s. despite of its discontinuity. In the late 1990s, few internal reforms have been carried. However, until the July First economic management improvement measure in 2002, the significant changes of North Korean development model has not been made. Above all, the July First measure is crucial, because external opening has been paralleled by the internal reform. The measure is characterized by strengthening material incentives, reflection of market signals, decentralization of planning, and recognition of market mechanism. In this regard, the measure signals the changes of North Korean development model. However, the future of North Korean development model is uncertain, because the changes of North Korean development model can threaten ``Yui1`` regime of North Korea, and its dominant ideology, namely ``Juche`` ideology.