عنوان مقاله [English]
Realization of plans and on time demands providing, is nowadays one of the most strategic goals in all production industries. This importance is caused by importance of customer position and also exploitation of resources. In this paper, the aggregate production planning problem is studied. Two objective function is considered for this problem. First, minimizing total cost elements and second, minimizing dissatisfaction of customer that comes about delay in demands delivery. Due to the importance of the customer place in nowadays competitive environment, the last objective function is added to problem to getting closer to the real world. Therefore, at first problem definition via objective functions, parameters, and decision variables are presented. Then mathematical model in multi objective is developed. Since, this problem has been proved as NP-Hard, an approximation method is also developed based on Non-dominated Sorting Genetic Algorithm II (NSGA-II). Finally this problem is solved applying two algorithm ε_Constraint and NSGA-II using standard data that is obtained from references. The result show good performance of the proposed method based on NSGA-II both in solution quality and running time.