Kap Hwan Kim

A crane scheduling method for port container terminals

Abstract This paper discusses the problem of scheduling quay cranes (QCs), the most important equipment in port terminals. A mixed-integer programming model, which considers various constraints related to the operation of QCs, was formulated. This study proposes a branch and bound (B & B) method to obtain the optimal solution of the QC scheduling problem and a heuristic search algorithm, called greedy randomized adaptive search procedure (GRASP), to overcome the computational difficulty of the B & B method. The performance of GRASP is compared with that of the B & B method.

Berth scheduling by simulated annealing

The objective of the berth-scheduling problem is to determine the berthing times and positions of containerships in port container terminals. Every vessel requires a specific amount of space in a wharf for a predetermined length of time to unload and load containers. In this study, a mixed-integer-linear-programming (MIP) model was formulated for the berth-scheduling problem. The simulated annealing algorithm was applied to the berth-scheduling problem to find near-optimal solutions. Experimental results showed that the simulated annealing algorithm obtains solutions that are similar to the optimal solutions found by the MIP model.

Deriving decision rules to locate export containers in container yards

Abstract A methodology is proposed to determine the storage location of an arriving export container considering its weight. We consider the configuration of the container stack and the weight distribution of containers in the yard-bay. A dynamic programming model is formulated to determine the storage location to minimize the number of relocation movements expected for the loading operation. We also develop a decision tree from the set of the optimal solutions to support real time decisions. The performance of the decision tree is evaluated by the number of decisions that are different from the optimal solutions of the slower dynamic programming solution method.

A scheduling method for Berth and Quay cranes

This paper discusses a method for scheduling Berth and Quay cranes, which are critical resources in port container terminals. An integer programming model is formulated by considering various practical constraints. A two-phase solution procedure is suggested for solving the mathematical model. The first phase determines the Berthing position and time of each vessel as well as the number of cranes assigned to each vessel at each time segment. The subgradient optimization technique is applied to obtain a near-optimal solution of the first phase. In the second phase, a detailed schedule for each Quay crane is constructed based on the solution found from the first phase. The dynamic programming technique is applied to solve the problem of the second phase. A numerical experiment was conducted to test the performance of the suggested algorithms.

Evaluation of the number of rehandles in container yards

Abstract The rehandling work influences the performance of transfer cranes significantly in a container terminal. The height and the width of a bay in the container stack are important decision variables in designing the storage configuration. And they are key factors which determine the average number of rehandles to pick up a container. In this paper, we propose a methodology to estimate the expected number of rehandles to pick up an arbitrary container and the total number of rehandles to pick up all the containers in a bay for a given initial stacking configuration. Simple tables and equations are provided to help the estimation of the number of rehandles.

A heuristic rule for relocating blocks

One of the most important objectives of the storage and pickup operations in block stacking systems is to minimize the number of relocations during the pickup operation. This study suggests two methods for determining the locations of relocated blocks. First, a branch-and-bound (B&B) algorithm is suggested. Next, a decision rule is proposed by using an estimator for an expected number of additional relocations for a stack. The performance of the decision rule was compared with that of the B&B algorithm.

An Optimal Routing Algorithm for a Transfer Crane in Port Container Terminals

This paper focuses on how to optimally route transfer cranes in a container yard during loading operations of export containers at port terminals. Decision variables are the number of containers that a transfer crane picks up at each yard-bay and the sequence of yard-bays that atransfer crane visits during a loading operation. This routing problem is formulated as a mixed integer program. The objective function of the formulation is to minimize the total container handling time of a transfer crane, which includes setup time at each yard-bay and travel time between yard-bays. Based on the mixed integer program, an optimizing algorithm is developed.

Segregating space allocation models for container inventories in port container terminals

This paper considers how to allocate storage space for import containers. In the segregation strategy, stacking newly arrived containers on the top of containers that arrived earlier is not allowed. We analyze cases where the arrival rate of import containers is constant, cyclic, and dynamic. Spaces are allocated for each arriving vessel so as to minimize the expected total number of rehandles. Mathematical models and solution procedures are suggested for obtaining the optimal solution. Numerical examples are provided in order to illustrate the solution procedure.

A note on a dynamic space-allocation method for outbound containers

Abstract Storage space is a critical resource in port container terminals. This paper discusses how to allocate storage space for outbound containers that will arrive at a storage yard. The main objectives of space allocation are to utilize space efficiently and make loading operations more efficient. Objective functions and constraints of both the direct and the indirect transfer systems are described and formulated. A basic model is formulated as a mixed-integer linear program. Two heuristic algorithms are suggested based on the duration-of-stay of containers and the sub-gradient optimization technique, respectively. A numerical experiment was conducted to compare two heuristic algorithms.

The optimal sizing of the storage space and handling facilities for import containers

This paper discusses a method of determining the optimal amount of storage space and the optimal number of transfer cranes for handling import containers. A cost model is developed for the decision making. The cost model consists of the space cost, the investment cost of transfer cranes, and the operating cost of transfer cranes and trucks. Two different cases are treated, one where the cost of only the terminal operator is minimized, and another where the total cost of both the terminal operator and the customers is minimized. For the former case, a deterministic model is developed, while for the latter case, a stochastic model is developed. Simple solution procedures for the models are provided. The solution procedures are illustrated using numerical examples.