• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.2
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• pp.68-77
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• 2004

This paper considers the workforce assignment problem to minimize both the deviations of workloads assigned to workers and to maximize the total preference between each worker and each machine. Because of the high expense of technology education and the difficulties of firing employees, there is no part time workers in semiconductor industry. Therefore, multi-skilled workers are trained for performing various operations in several machines. The bicriteria workforce assignment problem in this paper is not easy to obtain the optimal solution considering the aisle structure and it is belong to NP-class. The proposed heuristic algorithms are developed based on the combination of spacefilling curve technique, simulated annealing technique and graph theory focusing on the multiple-row machine layout. Examples are presented for the proposed algorithms how to find a good solution.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.725-730
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• 2000

Genetic algorithms based on the theory of natural selection, have been applied to many different fields, and have proven to be relatively robust means to search for global optimum and handle discontinuous or even discrete data. Genetic algorithms are widely used for unconstrained optimization problems. However, their application to constrained optimization problems remains unsettled. The most prevalent technique for coping with infeasible solutions is to penalize a population member for constraint violation. But, the weighting of a penalty for a particular problem constraint is usually determined in the heuristic way. Therefore this paper proposes, the effective technique for handling constraints, the ranking penalty method and hybrid genetic algorithms. And this paper proposes dynamic mutation tate to maintain the diversity in population. The effectiveness of the proposed algorithm is tested on several test problems and results are discussed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.4
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• pp.42-49
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• 2003

The branch and bound techniques based on cut tree and eigenvector have been Introduced in the literature [1, 2, 3, 6, 9, 12]. These techniques are used as a basis to allocate departments to floors and then to fit departments with unchangeable dimensions into floors. Grouping algorithms to allocate departments to each floor are developed and branch and bound forms the basis of optimizing using the criteria of rectilinear distance. The proposed branch and bound technique, in theory, will provide the optimal solution on two dimensional layout. If the runs are time and/or node limited, the proposed method is a strong heuristic The technique is made further practical by the fact that the solution is constrained such that the rectangular shape dimensions length and width are fixed and a perfect fit is generated if a fit is possible. Computational results obtained by cut tree-based algorithm and eigenvector-based algorithm are shown when the number of floors are two or three and there is an elevator.

• Proceedings of the Korea Association of Information Systems Conference
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• 2000.11a
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• pp.45-63
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• 2000

Facing in very repidly changing environments via information technologies, we need to study and develop new information technologies in postal delivery service in Korea. We study to find the near optimal route for the better postal service between the collection centers. Optimal routing decision for the postal delivery is NP-Hard. The main purpose of this paper is to develop the near optimal simulation technique for the postal routing decision. We consider the distance between collection centers, and the quantity of post articles in the collection center to obtain the near optimal route. We use the heuristic algorithm to obtain the near optimal solution for the transportation route of postal articles. Also, we try to show the transportation route by using the map after deciding the near optimal route.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.791-800
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• 2016

Optimal Power Flow (OPF) is an important operational and planning problem in minimizing the chosen objective functions of the power systems. The recent developments in power electronics have enabled introduction of dc links in the AC power systems with a view of making the operation more flexible, secure and economical. This paper formulates a new OPF to embrace dc link equations and presents a heuristic optimization technique, inspired by the behavior of fireflies, for solving the problem. The solution process involves AC/DC power flow and uses a self adaptive technique so as to avoid landing at the suboptimal solutions. It presents simulation results of IEEE test systems with a view of demonstrating its effectiveness.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.65
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• pp.89-102
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• 2001

In this paper, the aircraft route scheduling consists of two steps; the pairing generation and the aircraft assignment. The pairing generation is heuristic approach how flights construct pairings from and to the main base. The aircraft resource assignment which is to establish a aircraft route schedule is constructed by constraint satisfaction problem technique. ILOG solver and schedule is used to solve this problem. In addition, a aircraft route reschedule process against departure-arrival delay or aircraft maintenance schedule change is added by partial constraints satisfaction problem technique. Also, Gantt chart made by ILOG views is used to show aircraft route schedule results more easily.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.738-743
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• 1991

A multiobjective analysis technique was applied for the optimum operation of pumps and reservoirs in service water transmission systems. Three major objectives were identified and assessed on the normally operating service water transmission systems. They are, 1) stability of pump operation; 2) economic point of view in minimizing the energy cost for pumping; 3) reliability in meeting the stochasticaly varying demands. The measures of these objectives were required times of pump on-offs in stability, required total energy cost in economics, and minimum required storage during the operating horizon in reliability. In order to find the best meeting solution to the decision maker, a set of non-dominated solutions which show the tradeoff relationships between the considering objectives were generated. The DM selects the best solution from this explicit tradeoff relationships using his heuristic decision rules or experience. The theory was verified by applying to the Kumi Service Water System. A combined technique of the ${\varepsilon}-constraint$ and the weighting methods was used to generate the nondominated solutions, and the dynamic programming algorithm was applied to find the optimal solution for the discretized multi-objective analysis problems.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.3
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• pp.123-128
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• 2017

Electric utilities has been considered the necessity to introduce AM(asset management) of electric power facilities in order to reduce maintenance cost of existing facilities and to maximize profit. In order to make decisions in terms of repairs and replacements for power transformers, not only measuring by counting parts and labor costs, but comprehensive comparison including reliability and cost is needed. Therefore, this study is modeling input cost for power transformer during its entire life and also the life cycle cost (LCC) technique is applied. In particular, this paper presents an application of heuristic harmony search(HS) optimization algorithm to the convergence and the validity of economic life assessment of power transformer from LCC technique. This recently developed HS algorithm is conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary. The effectiveness of the proposed identification method has been demonstrated through an economic life assessment simulation of power transformer using HS optimization algorithm.

• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.473-481
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• 2002

Decryption of encrypted malicious scripts is essential in order to analyze the scripts and to determine whether they are malicious. An effective decryption technique is one that is designed to consider the characteristics of the script languages rather than the specific encryption patterns. However, currently X-raying and emulation are not the proper techniques for the script because they were designed to decrypt binary malicious codes. In addition to that, heuristic techniques are unable to decrypt unknown script codes that use unknown encryption techniques. In this paper, we propose a new technique that will be able to decrypt malicious scripts based on analytical approach. we describe its implementation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.3
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• pp.58-66
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• 2003

The cut tree approach of Montreuil and Ratliff [16] and eigenvector approach [10] are used to automatically draw a feasible facility layout with aisle structure. The department arrangement can minimize an aisle distance criterion considering door locations and dimension constraints. The aisle distance is measured by the door to door distance between departments. An eigenvector and cut tree approaches [1] are implemented based on the branch and bound technique in Kim et al. [2] in order to obtain feasible layouts. Then, the algorithm to fix the door location of each department is developed. After the door locations are determined, the factory layout is evaluated in terms of aisle distance. The aisle structure is obtained by expanding the original layout. The solution is kept until we will find better factory layout. The proposed approach based on the branch and bound technique, in theory, will provide the optimal solution. If the runs are time and/or node limited, the proposed method is a strong heuristic. The technique is made further practical by the fact that the solution is constrained such that the rectangular shape dimensions length(l) and width(w) are fixed and a perfect fit is generated if a fit is possible.