휴리스틱 알고리즘을 이용한 선박의 밸러스트수의 자동 교체 시스템 개발에 관한 연구

Abstract

A Study on the Development of Ship’s Ballast Water Sequential Exchange Planning Using Heuristic Algorithm

Hong, Chung-You Advisor : Prof. Park, Jae-Woong, Ph.D. Department of Advanced Marine Transportation Plan & Production Management, Graduate School of Chosun University

Harmful aquatic organism invasions through ballast water are recognized as a serious threat to global biological diversity and human health. Studies have shown that many species of bacteria, plants, and animals can survive in a viable form in the ballast water and sediment carried in ships, even after journeys of several months’ duration. Subsequent discharge of ballast water or sediment into the waters of port states may result in the establishment of these harmful organisms creating a detriment to the marine environment. The potential for ballast water discharge to cause harm has been recognized not only by the International Maritime Organization (IMO) but also by the World Health Organization (WHO), which is concerned about the role of ballast water as a medium for the spreading of disease bacteria. Ballast exchange is known to be effective, among the methods for Ballast Water Management, but potentially dangerous to the safe operation of ship, if performed incorrectly. Therefore, there is a great need to develop more effective and efficient approaches to ballast water exchange plan on ships. With the aforementioned regulations (guidelines), an optimal Ballast Water Exchange Plan is suggested as an automatic system based on IMO Guideline. To optimize the ballast water exchange sequences, the proposed system combines the features of a mechanical analysis and a hybrid optimization algorithm: meta-heuristic algorithm and uninformed searching algorithm. Heuristic algorithm A* was specially chosen for the general robustness of applicability and optimality. Three main factors (node, operator, and objective function) are, then, modified and redefined for the heuristic global solution of A* Algorithm. The entire sequence of exchange can be divided into the following steps. The node of modified A* algorithm is matched with each step of sequences in 'Exchange Module’ of ballast water plan. The entire optimum sequence can be, then, found with subsequent explorations from the starting node to the final goal node. The operator in modified A* algorithm is adopted in accordance with the capacities of pumps and the linking combinations between tanks and pumps. The objective function is evaluated to minimize the time frame for the current exchange sequence, giving penalties to these nodes that violate criteria. Therefore, the modified A* algorithm can be introduced as a heuristic approach to find the optimum sequence. The developed optimal Ballast Water Exchange Plan has been applied to various ballast conditions of ships (i.e., bulk carrier, tanker, and container carrier), which have installed loading instruments approved by classification society. From the test results, it has been concluded that the developed system is an effective and efficient optimization tool for the Ballast Water Exchange Plan in suitable computational time frame.