出口儲區取櫃問題為貨櫃裝船作業中重要的一環。為了有效使用儲位空間，貨櫃多以堆疊的方式存放，僅能由堆疊的最上方存取貨櫃，因此儲區存在壓櫃現象。壓櫃現象導致取櫃時需要額外、無直接生產力的翻櫃動作，因而影響儲區之作業效率。
本研究發展一套演算法用以處理取櫃問題之最佳化，求解如何以最少的搬動次數、最短的軌道型門式起重機(RMGC)工作時間，將所有貨櫃以已知的順序搬離儲區。本研究將取櫃問題分為三類。第一類為單吊、單一台RMGC取櫃問題，先以一演算法求解取櫃計畫，再將取櫃計畫建構成最短路徑模型，藉求解最短路徑來減少RMGC工作時間。第二類為多吊、單一台RMGC取櫃問題，則是將單吊、單一台RMGC之取櫃計畫，透過兩個貨櫃搬動動作之交換，將貨櫃搬動動作分配給數個夾櫃器處理。第三類為單吊、兩台RMGC取櫃問題，先將取櫃計畫分配給兩台RMGC，再以模擬的方法求得兩台RMGC完成其所負責之貨櫃搬動動作所需的時間。
測試結果顯示本研究求解出之單吊、單一台RMGC取櫃問題之取櫃計畫接近或等於搬動次數下限值。可求解2000個以上貨櫃的儲區之取櫃計畫。使用多個夾櫃器亦可減少搬動時間，並且有可能減少搬動次數，但多吊之效用隨夾櫃器數目增加而遞減。將取櫃計畫分配給兩台RMGC，總工作時間可以減少30%以上。

Retrieving export containers from a yard is an important part of the ship-loading process. Containers are stacked high to utilize yard space more efficiently, and can be accessed only from the top of each stack. Therefore, non-productive reshuffles are required to remove the containers stacked on top of a targert container in the process of retrieving containers. Reshuffles influence the efficiency of a container yard operation.
In this research we develop a heuristic to solve the container retrieval problem which yields a working plan for a rail mounted gantry crane(RMGC) to retrieve all the containers from a given export container yard in a given sequence. The optimization goal is to minimize the number of container movements and the RMGC’s working time. We study three variants of the container retrieval problem. The first one is single-lift and single RMGC container retrieval problem. We propose a heuristic to develop a retrieving plan. Next, we use the retrieving plan to construct a graph and solve the shortest path in the graph to reduce the RMGC’s working time. The second one is multi-lift and single RMGC container retrieval problem. Assigning the movements to multiple spreaders is done by exchanging the movements of the single-lift and single RMGC retrieving plan. The third one is single-lift and multiple RMGCs container retrieval problem. First, assign the movements to two RMGCs. Second, calculating the time for the two RMGCs to finish their tasks by simulation.
Numerical testing results show that the number of container movements of the single-lift and single RMGC retrieving plan approaches or equals the lower bound. The heuristic is able to solve instances with more than 2000 containers. Using multiple spreaders can reduce RMGC’s working time as well as the number of container movements. The effect of multi-lift is decreasing with the increase in spreaders. Using two RMGCs to execute the retrieving plan can reduce the RMGC’s working time by more than 30%.

1. 林美利, 港區貨櫃場儲區作業模式評選之研究. 民國97年, 國立臺灣海洋大學航運管理學系碩士學位論文.
2. Kim, K.H. and J.W. Bae, Re-marshaling export containers in port container terminals. Computers & Industrial Engineering, 1998. 35(3-4): p. 655-658.
3. Lee, Y. and N. Hsu, An optimization model for the container pre-marshalling problem. Computers & Operations Research, 2007. 34(11): p. 3295-3313.
4. Lee, Y. and S. Chao, A neighborhood search heuristic for pre-marshalling export containers. European Journal of Operational Research, 2009. 196(2): p. 468-475.
5. Choe, R., et al., Generating a rehandling-free intra-block remarshaling plan for an automated container yard. Journal of Intelligent Manufacturing, 2009: p. 1-17.
6. Kim, K. and G. Hong, A heuristic rule for relocating blocks. Computers & Operations Research, 2006. 33(4): p. 940-954.
7. Lee, Y. and Y.-J. Lee, A heuristic for retrieving containers from a yard. Computers & Operations Research, 2010. 37(6): p. 1139-1147.
8. Forster, F. and A. Bortfeldt, A tree search procedure for the container relocation problem. Computers & Operations Research, 2012. 39(2): p. 299-309.
9. Ng, W.C., Crane scheduling in container yards with inter-crane interference. European Journal of Operational Research, 2005. 164(1): p. 64-78.
10. Li, W., et al., Discrete time model and algorithms for container yard crane scheduling. European Journal of Operational Research, 2009. 198(1): p. 165-172.
11. Park, T., et al., Real-time scheduling for twin RMGs in an automated container yard. OR Spectrum, 2010. 32(3): p. 593-615.
12. Kemme, N., Effects of storage block layout and automated yard crane systems on the performance of seaport container terminals. OR Spectrum, 2011: p. 1-29.
13. 紀國斌, 多部軌道式門型起重機排程最佳化之研究. 民國93年, 國立台灣海洋大學航運管理學研究所碩士論文.
14. 許乃云, 貨櫃儲區整櫃之最佳化網路模式. 民國91年, 國立成功大學土木工程學研究所碩士論文.