Maryam Bakhshi - Department of Industrial Engineering, Arak Branch, Islamic Azad University, Arak, Iran.
Seyed Emadedin Hashemi - Department of Industrial Engineering, Arak Branch, Islamic Azad University, Arak, Iran.
Habib Dezhdar - Department of Industrial Engineering, Arak Branch, Islamic Azad University, Arak, Iran.

In this research, we present a mathematical model for allocating people to different jobs and shifting employees between related jobs. This action will reduce the repetitive activities workload and ergonomic risks at the planned time horizon, and finally increases the organization's efficiency. In this proposed model, the devices are semi-automatic and it is possible to allocated more than one task to one person. Regarding the modeling and the case study of the constraints, it is shown that the complexity of this problem type is NP-Hard, and the result of accurate methods for solving the problem is not possible in a reasonable time. Due to this Simulated Annealing (SA) algorithm is used to study the proposed model and comparison of the results of SA algorithm with the results of precise optimization methods shows the better performance of the Simulated Annealing algorithm in terms of the time and answer quality.

Job Rotation, Mathematical Modeling, physical injuries, Simulated Annealing Algorithm