• Journal of Korean Institute of Industrial Engineers
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• v.18 no.2
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• pp.141-147
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• 1992

This article evaluates the efficiency of three branch-and-bound heuristics for a job scheduling problem that minimizes the sum of absolute deviations of completion times from a common due date. To improve the performance of the branch-and-bound procedure, Algorithm SA is presented for the initial feasible schedule and three heuristics : breadth-first, depth-first and best-first search are investigated depending on the candidate selection procedure. For the three heuristics the CPU time, memory space, and the number of nodes generated are computed and tested with nine small examples (6 ${\leq}$ n ${\leq}$ 4). Medium sized random problems (10 ${\leq}$ n ${\leq}$ 30) are also generated and examined. The computational results are compared and discussed for the three heuristics.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.57-63
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• 2012

Software release planning model of software product lines was formulated as a precedence-constrained multiple 0-1 knapsack problem. The purpose of the model was to maximize the total profit of an entire set of selected features in a software product line over a multi-release planning horizon. The solution approach is a dynamic programming procedure. Feasible solutions at each stage in dynamic programming are determined by using backward dynamic programming approach while dynamic programming for multi-release planning is forward approach. The pre-processing procedure with a heuristic and reduction algorithm was applied to the single-release problems corresponding to each stage in multi-release dynamic programming in order to reduce the problem size. The heuristic algorithm is used to find a lower bound to the problem. The reduction method makes use of the lower bound to fix a number of variables at either 0 or 1. Then the reduced problem can be solved easily by the dynamic programming approaches. These procedures keep on going until release t = T. A numerical example was developed to show how well the solution procedures in this research works on it. Future work in this area could include the development of a heuristic to obtain lower bounds closer to the optimal solution to the model in this article, as well as computational test of the heuristic algorithm and the exact solution approach developed in this paper. Also, more constraints reflecting the characteristics of software product lines may be added to the model. For instance, other resources such as multiple teams, each developing one product or a platform in a software product line could be added to the model.

• Journal of the Korean Operations Research and Management Science Society
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• v.19 no.3
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• pp.219-233
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• 1994

A fixed k-coloring problem is introduced and dealt with by efficient heuristic algorithms. It is shown that the problem can be transformed into the graph partitioning problem. Initial coloring and improving methods are proposed for problems with and with and without the size restriction. Algorithm Move, LEE and OEE are developed by modifying the Kernighan-Lin's two way uniform partitioning procedure. The use of global information in the selection of the node and the color set made the proposed algorithms superior to the existing method. The computational result also shows that the superiority does not sacrifice the time demand of the proposed algorithms.

• Journal of Korean Institute of Industrial Engineers
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• v.12 no.1
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• pp.13-18
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• 1986

This paper is concerned with flow-shop permutation scheduling problem. This paper presents an algorithm for the minimum makespan sequence. The efficiency of proposed algorithm is demonstrated by comparisons with the existing algorithms: Johnson's, branch & bound method, and heuristic algorithms. The proposed algorithm is more effective than the other algorithms. A numerical example is given to illustrate the procedure.

• Industrial Engineering and Management Systems
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• v.4 no.2
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• pp.123-128
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• 2005

The author derives a general explicit formula and presents an heuristic algorithm for solving Baker’s model. The examples show that this new approximate solution procedure for determining near optimum inspection intervals is more accurate than the ones suggested by Chung (1993) and Vaurio (1994), and is more efficient computationally than the one suggested by Hariga (1996). The construction and solution of the simplest profit model for an exponential failure distribution were presented in Baker (1990), and approximate analytical results were obtained by Chung (1993) and Vaurio (1994). The author will therefore mainly devote the following discussion to the problem of further approximating optimum inspection intervals.

• Management Science and Financial Engineering
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• v.8 no.2
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• pp.1-20
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• 2002

This paper presents a model that analyzes the impact of uncertainties in demand and processing times on the production lead time of a Kanban system. We consider the waste associated with under-production as well as over-production when we measure the production lead time. We set up an optimization model to minimize the production lead time. A simple heuristic procedure is developed to determine solutions in terms of the size of containers and the number of Kanban cards. In addition, we numerically examine the behavior of the optimal Kanban system.

• Management Science and Financial Engineering
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• v.10 no.2
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• pp.89-102
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• 2004

In this paper, we deal with a processor assignment problem that minimizes the total traffic load of an ATM switch controller by optimally assigning processors to ATM interface units. We develop an integer programming (IP) model for the problem, and devise an effective tabu search heuristic. Computational results reveal the efficacy of the proposed tabu search procedure, finding a good quality solution within 5% of optimality gap.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2008.10a
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• pp.308-311
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• 2008

The ant colony optimization (ACO) is a metaheuristic inspired by the behavior of real ants. Recently, ACO has been widely used to solve the difficult combinatorial optimization problems. In this paper, we propose an ACO algorithm to solve the two disjoint paths problem with dual link cost structure (TDPDCP). We propose a dual pheromone structure and a procedure for solution construction which is appropriate for the TDPDCP. Computational comparisons with the state-of-the-arts algorithms are also provided.

• Journal of the Korea Safety Management & Science
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• v.3 no.3
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• pp.97-106
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• 2001

This paper considers automated storage and retrieval systems with double shuttle. We developed the expected travel time model based on the first come first served rule. An heuristic procedure by retrieval order sequencing was presented which aimed to improve the operation efficiency laking advantage of ＂No cost zone＂. Through sensitivity study, we evaluated the performance of the double shuttle system working on the four command cycle.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1782-1793
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• 1989

Stroke crossing number, syntactic pattern recognition procedure, top down recognition structure, and heuristic approach are studied for the Korean text recognition. We propose new algorithms: 1)Korean vowel seperation using limited scanning method in the Korean characters, 2) extracting strokes using stroke width method, 3) stroke crossing number and its properties, 4) average, standard deviation, and mode of stroke crossing number, and 5) classification and recognition methods of limited chinese character. These are studied with computer simuladtions and experiments.