• 한국경영과학회지
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• 제36권1호
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• pp.27-38
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• 2011

In this paper, we deal with the periodic heterogeneous fleet vehicle routing problem (PHVRP). PHVRP is a problem of designing vehicle routes in each day of given period to minimize the sum of fixed cost and variable cost over the planning horizon. Each customer can be visited once or more times over the planning horizon according to the service combinations of that customer. Due to the complexity of the problem, we suggest a heuristic algorithm in which an initial solution is obtained by assigning the customer-day and the customer-car simultaneously and then it is improved. A performance of the proposed algorithm was compared to both well-known results and new test problems.

• 한국경영과학회지
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• 제18권1호
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• pp.29-43
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• 1993

This paper condisers a problem of determining arc capacities for a communication network with fixed-charged linear arc-cost functions, which is known to be NP-hard. For the problem, an efficient heuristic solution procedure is derived. The procedure is further shown working well for designing arc capacities of a network in a situation where the network needs to be extended by connecting its nodes to some new nodes or where the network needs to be extended by expanding its arc capacities.

• 산업경영시스템학회지
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• 제19권40호
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• pp.169-178
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• 1996

Geographically dispersed computing system is made of computers interconnected by a telecommunications network. To make the system operated efficiently, system designer must determine the allocation of data files to each node. In designing such distributed computing system, the most important issue is the determination of the numbers and the locations where database files are allocated. This is commonly referred to as the file allocation problem (FAP)[3]. The proposed model is a 0/l integer programming problem minimizing the sum of file storage costs and communication(query and update) costs. File allocation problem belongs to the class of NP-Complete problems. Because of the complexity, it is hard to solve. So, this paper presents an efficient heuristic algorithm to solve the file allocation problem using Tabu Search Technique. By comparing the optimal solutions with the heuristic solutions, it is believed that the proposed heuristic algorithm gives good solutions. Through the experimentation of various starting points and tabu restrictions, this paper presents fast and efficient method to solve the file allocation problem in the distributed computing system.

• 대한산업공학회지
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• 제19권3호
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• pp.37-49
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• 1993

In this paper, the TSP(traveling salesman problem) which its costs(distance) between nodes are defined with Max($\bar{x}$, $\bar{y}$) has been dealt. In order to find a satisfactory solution for this kind of problem, we generate weighted matrix, and then develope a new heuristic problem solving method using the weighted matrix. Also we analyze the effectiveness of the newly developed heuristic method comparing it with other heuristic algorithm already exists for Euclidean TSP. Finally, we apply a new developed algorithm to real Max($\bar{x}$,$\bar{y}$) TSP such as PCB inserting.

• 대한산업공학회지
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• 제23권3호
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• pp.451-467
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• 1997

Tabu search (TS) is a useful strategy that has been successfully applied to a number of complex combinatorial optimization problems. By guiding the search using flexible memory processes and accepting disimproved solutions at some iterations, TS helps alleviate the risk of being trapped at a local optimum. In this article, we propose TS-based heuristics for solving a class of clustering problems, and compare the relative performances of the TS-based heuristic and the simulated annealing (SA) algorithm. Computational experiments show that the TS-based heuristic with a long-term memory offers a higher possibility of finding a better solution, while the TS-based heuristic without a long-term memory performs better than the others in terms of the combined measure of solution quality and computing effort required.

• 대한산업공학회지
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• 제27권1호
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• pp.18-24
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• 2001

This paper presents a model and a heuristic algorithm for the Traveling Salesman Problem with Time Windows(TSPTW). The main difference of our model compared with the previous ones lies in that the time windows we are concerned are more flexible and realistic than the previous ones. In the typical TSPTW, the service at a node must begin within the time grid called the time window that is defined by the earliest and the latest time to start the service at each node. But, in real business practice, a lateness cost is usually penalized rather than the service is prohibited at all when a vehicle arrives after the latest time. Considering this situation, we develop a model with a new time window that allows an arrival after the latest time and penalizes the late arrival by charging a lateness cost. A two-phased heuristic algorithm is proposed for the model and is extensively tested to verify the accuracy and efficiency of the algorithm.

• 전자통신동향분석
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• 제14권6호통권60호
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• pp.31-37
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• 1999

정보검색시스템에서는 방대한 양의 데이터에서 보다 효율적이고, 보다 정확한 데이터를 어떻게 추출할 것인가가 항상 가장 중요한 문제로 인식되어 왔다. 특히, 앞으로 데이터베이스는 지식정보를 담는 대규모 데이터베이스가 되므로 이러한 문제를 해결하기 위한 방법은 갈수록 복잡해 질 것이다. 현재 이의 해법으로 데이터마이닝에 대한 연구가 활발하게 진전되고 있으며, 특히 문서의 연관관계를 정의해 주는 클러스터링은 향후 지식발견의 가장 중요한 요소가 될 것으로 보인다. 따라서, 본 논문은 대규모 데이터베이스에서 지식정보 발견에 관한 기법에 대한 최근의 연구동향을 소개한다. 즉, 이용자 질의에 대한 검색 결과를 개선하기 위한 방편인 데이터마이닝 기법의 기본개념과 데이터마이닝 기법 중에서도 최근 가장 빠르게 실용화가 이루어지고 있는 클러스터링에 대한 최근의 동향을 살펴본다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
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• pp.433-440
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• 2003

통신시스템의 발전과 더불어 WDM 전송기술의 등장은 미래의 다양한 광대역 서비스의 제공이 가능하게 되었다. 하지만, 개별 수요들이 요구하는 대역폭이 광파장의 대역폭에 비해 매우 작으므로. 개별 수요들을 다중화하여 하나의 광경로를 통해 전송하는 수요집적(traffic grooming)에 관한 연구들이 많은 관심을 받고. 있다 본 연구는 mesh 구조의 WDM 통신망에서의 수요집적 및 광경로 설정에 관한 문제를 다루고 있다. 주어진 네트워크 상에 하나의 가상노드와 아크를 추가하여 새로운 네트워크를 구성하고 이를 대상으로 목적함수를 사용되는 광파장의 수를 최소화하는 혼합정수계획 모형을 수립하였다. 아울러. NP-Complete로 알려진 본 문제의 해를 효과적으로 구하기 위한 발견적 해법을 제안하며, 실제 다양한 실험을 통해 제안된 알고리즘의 효율성을 보인다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.1733-1739
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• 2006

This paper is concerned with multi-objective vehicle routing problem(VRP), in which objective of this problem is to minimize the total operating time of vehicles and the total tardiness of customers. A mixed integer programming formulation and a heuristic for practical use are suggested. The heuristic is based on the route-perturbation and route-improvement method(RPRI). Performances are compared with other heuristic appeared in the previous literature using the modified bench-mark data set. It is shown that the suggested heuristic give good solution within a short computation time by computational experiment.

• 한국경영과학회지
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• 제21권2호
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• pp.111-124
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• 1996

The main purpose of this study is to develop an algorithm to solve the scheduling problems of FMS using Petri-net is well suited to model the dynamics of FMS and Petri-net is an ideal tool to formulate scheduling problems with routing flexibility and shared resources. By using the marking of Petri-net, We can model features of discrete even system, such as concurrency, asynchronous, conflict and non-determinism. The proposed algorithm in this paper can handle back-tracking using the marking of Petri-net. The results of the experiment show that marking is one of the best ways that describe exactly movement of the discrete event system. To show the effectiveness of the algorithm suggested here, we compare it with L1 algorithm using the Petri-net through the test on randomly generated test problems.