• Journal of the Korean Operations Research and Management Science Society
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• v.10 no.1
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• pp.1-8
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• 1985

By introducing the concept of reliability of parallel systems the set covering. A branch-and-bound algorithm is developed and illustrated by a numerical example. The procedure has been coded and its computational efficiency is studied.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.22
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• pp.65-69
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• 1990

Two different algorithms for traveling salesman problem(TSP) will be discussed. One is the engineering approach to the TSP. The other one is Branch-and-Bound algorithm to take advantage of the special structure of combinational problems. Also a generalization of TSP will be presented.

• Journal of the Korean Operations Research and Management Science Society
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• v.32 no.4
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• pp.51-60
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• 2007

In this study, we consider the minimum ADM problem which is the fundamental problem for the cost-effective design of SONET ADM embedded in WDM ring networks. To minimize the number of SONET ADMs, efficient algorithms for the routing and wavelength assignment are needed. We propose a mathematical model based on the graph theory for the problem and propose a branch-and-price approach to solve the suggested model effectively within reasonable time. By exploiting the mathematical structure of ring networks, we developed polynomial time algorithms for column generation subroutine at branch-and-bound tree. In a computer simulation study, the suggested approach can find the optimal solution for sufficient size networks and shows better performance than the greedy heuristic method.

• Journal of applied mathematics & informatics
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• v.8 no.1
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• pp.181-197
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• 2001

A heuristic method TABU-CSP using Tabu Search (TS) is described for solving Constraint Satisfaction Problems (CSPs). The method is started with a complete but inconsistent solution of a binary CSP and obtained in prespecified number of iterations either a consistent solution or a near optimal solution with an acceptable number of conflicts. The repair in the solution at each iterative step is done by using two heuristics alternatively. The first heuristic is a min-conflicts heuristic that chooses a variable with the maximum number of conflicts and reassigns it the value which leads to the minimum number of conflicts. If the acceptable solution is not reached after the search continued for a certain number of iterations, the min-conflict heuristic is changed and the variable selected least number of times is chosen for repair. If an acceptable solution is not reached, the method switches back to the min-conflict heuristic and proceeds further. This allowed the method to explore a different region of search space space for the solution as well as to prevent cycling. The demonstration of the method is shown on a toy problem [9]which has no solution. The method is then tested on various randomly generated CSPs with different starting solutions. The performance of the proposed method in terms of the average number of consistency is checked and the average number of conflicts is conflicts is compared with that of the Branch and Bound(BB) method used to obtain the same solution. In almost all cases, the proposed method moves faster to the acceptable solution than BB.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.2
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• pp.129-138
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• 2016

This paper presents a natural corners-based SLAM (Simultaneous Localization and Mapping) with a robust data association algorithm in a real unknown environment. Corners are extracted from raw laser sensor data, which are chosen as landmarks for correcting the pose of mobile robot and building the map. In the proposed data association method, the extracted corners in every step are separated into several groups with small numbers of corners. In each group, local best matching vector between new corners and stored ones is found by joint compatibility, while nearest feature for every new corner is checked by individual compatibility. All these groups with local best matching vector and nearest feature candidate of each new corner are combined by partial compatibility with linear matching time. Finally, SLAM experiment results in an indoor environment based on the extracted corners show good robustness and low computation complexity of the proposed algorithms in comparison with existing methods.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2187-2195
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• 2017

In order to solve the AC optimal power flow (OPF) problem considering the generators' on/off status, it is necessary to model the problem as mixed-integer nonlinear programming (MINLP). Because the computation time to find the optimal solution to the mixed-integer AC OPF problem increases significantly as the system becomes larger, most of the existing solutions simplify the problem either by deciding the on/off status of generators using a separate unit commitment algorithm or by ignoring the minimum output of the generators. Even though this kind of simplification may make the overall computation time tractable, the results can be significantly erroneous. This paper proposes a novel algorithm for the mixed-integer AC OPF problem, which can provide a near-optimal solution quickly and efficiently. The proposed method is based on a combination of the outer approximation method and the relaxed AC OPF theory. The method is applied to a real-scale power system that has 457 generators and 2132 buses, and the result is compared to the branch-and-bound (B&B) method and the genetic algorithm. The results of the proposed method are almost identical to those of the compared methods, but computation time is significantly shorter.

• Annual Conference of KIPS
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• 2017.04a
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• pp.829-830
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• 2017

스카이라인 질의는 '지배(dominate)'관계를 적용한 선호도 질의(preference query)의 한 종류로, 복수의 기준을 이용한 의사 결정 시 사용된다. 스카이라인 질의 결과는 다수의 선택지 중에서 사용자가 다른 객체에 비해 뒤처지지 않는 선택지를 제시함으로써 사용자가 검토해야하는 선택지의 수를 대폭 감소시키기 때문에 대용량 데이터 분석 시 매우 유용하게 활용될 수 있다. 본 논문에서는 기존에 제시된 BBS(Branch and Bound Skyline Computation)에서 사용되고 있는 평가함수를 설명하고, 스카이라인 계산을 위해 사용할 수 있는 대안 평가함수의 속성을 제시한다. 또한 다양한 대안 평가함수를 사용한 실험을 통해 성능을 분석했으며, 이를 통해 기존 기법의 성능보다 좋은 평가함수가 존재함을 보였다.

• The Journal of the Korea Contents Association
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• v.6 no.4
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• pp.46-54
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• 2006

We propose an optimization method for PCB assembly lines including multiple surface mounters. To increase the productivity of PCB assembly line, the component allocation, feeder assignment, and assembly sequence of each surface mounter should be optimized. The optimization Problem is formulated as an integer programming problem. We divide the overall problem into two hierarchical sub-problems: forward-path problem and backward-path problem. The clustering algorithm and branch-and-bound algorithm are applied to solve the forward-path problem. The assignment algorithm and connection algorithm are applied to solve the backward-path problem. Simulation results are presented to verify the usefulness of the proposed method.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.3
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• pp.101-109
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• 2008

This paper considers an integrated decision for scheduling and outsourcing(or, subcontracting) of a finite number of jobs(or, orders) in a time-sensitive make-to-order manufacturing environment. The jobs can be either processed in a parallel in-house facilities or outsourced to subcontractors. We should determine which jobs should be processed in-house and which jobs should be outsourced. And, we should determine the schedule for the jobs to be processed in-house. If a job is determined to be processed in-house, then the scheduling cost(the completion time of the Job) is imposed. Otherwise(if the job should be outsourced), then an additional outsourcing cost is imposed. The objective is to minimize the linear combination of scheduling and outsourcing costs under a budget constraint for the total available outsourcing cost. In the problem analysis, we first characterize some solution properties and then derive dynamic programming and branch-and- bound algorithms. An efficient heuristic is also developed. The performances of the proposed algorithms are evaluated through various numerical experiments.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.7
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• pp.405-413
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• 2004

Traditionally, electrical power systems had the vertically-integrated industry structures based on the economics of scale. However power systems have been recently reformed to increase the energy efficiency of the power system. According to these trends, Korean power industry has been partially restructured, and the competitive generation market was opened in 2001. In competitive electric markets, correct demand data are one of the most important issue to maintain the flexible electric markets as well as the reliable power systems. However, the measuring load data can have the uncertainty because of mechanical trouble, communication jamming, and other things. To obtain the reliable load data, an efficient evaluation technique to adust the missing load data is needed. This paper analyzes the load pattern of historical real data and then the turned ARIMA (Autoregressive Integrated Moving Average) model, PCHIP(Piecewise Cubic Interporation) and Branch & Bound method are applied to seek the missing parameters. The proposed method is tested under a variety of conditions and tested with historical measured data from the Korea Energy Management Corporation (KEMCO).