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수익을 최대로 하는 픽업 및 배송문제의 세분화 타부서치 알고리즘 기법 연구
김경근(Kyung Gun Kim),엄현섭(Hyun Seop Uhm),이영훈(Young Hoon Lee),태현철(Hyunchul Tae) 한국경영과학회 2021 한국경영과학회지 Vol.46 No.4
In this paper, we propose the granular tabu search heuristic for the pickup and delivery problem to maximize the total revenue by transportation of customer demands with a limited fleet of vehicles. The problem, denoted as the pickup and delivery maximum covering problem, is designed for the efficient operation of military air transportation system, it also can be applied to the competitive door-to-door transportation systems. In the problem, there exist several transportation requests, each of which consists of demand volume, price value, and unique pickup and delivery locations. The company maximizes the sum of the price value from allocated customers under the vehicle capacity and the maximum route length constraints. Since the suggested mathematical formulation is too hard to solve within the reasonable computational time, the local search heuristic algorithm is suggested. The algorithm contains two procedures for the efficient search of neighbor solutions, and the first suggestion is the granularity condition that only considers the edges with smaller cost-per-price value than the given threshold. The procedure not only reduces the computational requirements for the local search significantly but also keeps the solution quality compared to the results without the granularity condition. Also, we use the short-term memory procedure from the tabu search heuristic to prevent the repetition in a sequence of solutions. Test results show that the mathematical formulation is difficult to solve with commercial optimization software due to the NP-hardness. Also, we analyze the algorithm’s performance with various value of granular threshold, and the results show the advantages of the granularity condition.
정인웅(Inwoong Jung),엄현섭(Hyun Seop Uhm),이영훈(Young Hoon Lee) 한국경영과학회 2018 한국경영과학회지 Vol.43 No.4
As the environmental effect is becoming increasingly important in urban life, an eco-friendly bike sharing system has been considered as a good alternative transportation system. Most of the bike-sharing systems operate in a one-way mode, in which users can borrow a bike from any station and return it wherever they want. Hence, an imbalance exists between the supply and the demand of each station, and in such a situation, the operators must relocate bicycles using an inter-station vehicle (truck). In this study, we focused on dynamic repositioning, which relocates bikes several times a day. A mathematical model for an optimal dynamic repositioning operation plan is proposed, which can be executed once a day. This model considers pickup and delivery vehicle routing under time constraints and aims to minimize the number of unbalanced bikes while ensuring target fulfillment as close as possible. The relocating vehicle may visit several stations to pick up and deliver bikes needed within a time allowed for operation. The suggested model is evaluated through the standard cases with reasonable size and the real cases of Seoul city as well. Results indicate that the bike-sharing system can be operated efficiently to meet demand with practical implementation validity
문재경(Jae Kyeong Moon),엄현섭(Hyun Seop Uhm),태현철(Hyun Chul Tae) 한국산업경영시스템학회 2021 한국산업경영시스템학회지 Vol.44 No.4
The printing process can have to print various colors with a limited capacity of printing facility such as ink containers that are needed cleaning to change color. In each container, cleaning time exists to assign corresponding inks, and it is considered as the setup cost required to reduce the increasing productivity. The existing manual method, which is based on the worker’s experience or intuition, is difficult to respond to the diversification of color requirements, mathematical modeling and algorithms are suggested for efficient scheduling. In this study, we propose a new type of scheduling problem for the printing process. First, we suggest a mathematical model that optimizes the color assignment and scheduling. Although the suggested model guarantees global optimality, it needs a lot of computational time to solve. Thus, we decompose the original problem into sequencing orders and allocating ink problems. An approximate function is used to compute the job scheduling, and local search heuristic based on 2-opt algorithm is suggested for reducing computational time. In order to verify the effectiveness of our method, we compared the algorithms performance. The results show that the suggested decomposition structure can find acceptable solutions within a reasonable time. Also, we present schematized results for field application.
노남선(Nam Sun Noh),엄현섭(Hyun Seop Uhm),이영훈(Young Hoon Lee) 한국경영과학회 2018 韓國經營科學會誌 Vol.43 No.3
Air power missions suffer from target allocation (WTA) issues, and resolving these issues is an important goal in air power operations to effectively destroy targets in a fixed area. A key consideration is the space separation between flight resources, in which the horizontal-vertical spatial separation between each flight resource entering an enemy zone should be considered. Spatial separation is regarded fundamental in successful mission performance, and it increases the viability of an aircraft to accomplish a given operation. Another important consideration is the speed of operations. Determining the shortest distance between the air power platform and an assigned moving target can help speed up operational performance and increase survival. However, swift operations not only rely on the shortest distance toward an assigned moving target within a zone but also how the moving targets enter and exit the zone. This paper presents an effective method for spatial separation within a given area and a model for rapid operation considering entry and egress.