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Risks mean cases of uncertainty of project, the impact of which is realized as a threat (negative aspect) and/or opportunity (positive aspect). The traditional viewpoint on risk is a negative viewpoint that implies damages, loss and harmful consequences. Judgments such as this on risk merely emphasize on risks management and pay less attention to opportunities management. It is clear that some uncertainties might be profitable for the project as in many cases, it could be the source of loss. In a developed attitude, focus is made on a common process that could address the integrated management of both opportunities and risks to aim at maximizing the positive effectsopportunities-, and minimizing negative effects- risks-. Therefore, existence of causal-effect relations between risks, relationship, effects of risks and opportunities on each other and variety of strategies in facing risks gives no alternative for risk management team than taking integrated management of risks and opportunities. In another word, reaction to risks, with respect to risks and/or relevant opportunities, separately, will be never effective. In this paper, for the purpose of integrated management of risks and opportunities, the stages of quality analysis and reactions to risk are combined. The method which is used for reaction towards risk is a procedure based on dynamic system. Dynamic system is highly important among uncertainties due to considering the type and intensity of effects. By using dynamic system and attention to the relationship between uncertainties (risks/ opportunities), reaction to risk and decision making on employing suitable strategies to face risks will be more precise and accurate.

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Project Management knowledge has been used in many project oriented organizations in last two decades across the world. Despite, rate of project success did not change during these years. We believe there is a basic challenge in projects environment for managing them based on its inherent characteristics. In fact, project management knowledge use theories and concepts that are belong to process management world, as a different world. There is no enough attention to project characteristics as a fundamental differentiation for coping projects. Identification of construction projects nature in order to discern variables that create the project behaviors is main concern of the paper.Considering project characteristics in this research revealed construction project nature creates from combination two aspects. First, detecting environmental changes to develop a need and second prepare resources structure to respond the need. Important management challenge in this model is environmental continuous changes that alter the need and exchange resources structure. So, the paper considers how these aspects can be operationalized for developing a dynamic project management model. It gives some ideas about why project complexity might be considered to be increasing, and how construction projects move towards shorter timescales. The effectiveness of the model is verified by applying it for predicting some construction projects behavior. The results of the paper may capable future project managers to test any decision before its applying and lead to a new project management tool for construction projects management.