The stocker is a critical material handling system for transporting work-in-process materials in a display fab. Efficient dispatching is particularly challenging in twin-crane systems. The cranes share a single track while jobs arrive dynamically. In this study, we consider a weight-based dispatching method that combines multiple dispatching rules. The weight set determines the relative importance of multiple dispatching rules with competing objectives such as job priority and travel time, and its effectiveness varies with system dynamics. Evaluating weight sets requires simulation in stochastic and dynamic systems, which is computationally expensive. We therefore propose a simulation optimization framework to efficiently search the best weight set. Gaussian process- based Bayesian optimization is employed to guide the search under a limited simulation budget. Experimental results show that the relative importance of dispatching rules changes across scenarios. The proposed framework consistently identifies effective weight sets across diverse operating conditions.

1. Introduction
2. Literature Review
3. System and Problem Description
    3.1 Stocker System and Lot Dispatching Rule
    3.2 Weight-based Dispatching Rule
    3.3 Weight optimization problem
4. Methodology
    4.1 Proposed Framework
    4.2 Bayesian Optimization
5. Experiment and Results
    5.1 Experimental Design
    5.2 Experimental Results
6. Conclusion
Acknowledgement
References
Appendix

• Jonghyeon Chun(Major in Industrial Data Science and Engineering, Department of Industrial Engineering, Pusan National University) | 천종현 (부산대학교 산업공학과 산업데이터공학융합전공)
• Bosung Kim(Major in Industrial Data Science and Engineering, Department of Industrial Engineering, Pusan National University) | 김보성 (부산대학교 산업공학과 산업데이터공학융합전공)
• Min Hong(Mobile Display Logistics Automation Team, Samsung Display) | 홍민 (삼성디스플레이 중소형사업부 물류자동화팀)
• Soondo Hong(Department of Industrial Engineering, Pusan National University) | 홍순도 (부산대학교 산업공학과) Corresponding author