• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.489-491
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• 1993

Many optimization problem or multiple attribute, multiple alternative decision making problem may have fuzzy evaluation factors. In this case, fuzzy number operation technique is needed to evaluate and compare object functions which become fuzzy sets. Generally, fuzzy number operations can be defined by extension principle of fuzzy set theory, but it is tedious to do fuzzy number operations by using extension principle when the membership functions are defined by complex functions. Many fast methods which approximate the membership functions such as triangle, trapezoidal, or L-R type functions are proposed. In this paper, a fast fuzzy number operation method is proposed which do not simplify the membership functions of fuzzy numbers.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.762-763
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• 2016

동형 암호화 시스템을 구현하는 데 있어, encrypt, decrypt, recrypt 연산은 큰 골격을 이루는 연산이다. 각각에 있어 공통된 가장 중요한 연산은 백만 비트가 넘는 큰 정수에 대한 법 곱셈이며, 이것은 푸리에 변환을 반복적으로 수행하여 얻을 수 있는 매우 큰 정수에 대한 곱셈 연산과 곱셈 결과에 대한 법 간소화를 요구한다. 본 논문에서는 Schonhage-Strassen이 제안한 큰 정수에 대한 법 곱셈을 수행하는 알고리즘을 응용하여, 이를 다시 메모리를 절약할 수 있는 효율적인 알고리즘을 제안하고 구현한다. 제안한 정수 푸리에 변환 구조는 FPGA에 구현하여 성능을 비교하였다.

• 한국국방경영분석학회지
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• 제16권2호
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• pp.83-95
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• 1990

This paper addresses the problem of determining the optimal number of spares for a system consisting of multi-item parts. In commercial sector, the cost minimization is mainly considered as an objective functions in most inventory models. However, in the military inventory systems, it is more stressed on maximizing the system availability than minimizing the system cost because the field commander always wants the system to be in perfect working condition to prepare against an emergence case. In this point of view, this paper develops an inventory model which decides the optimal number of spares by minimizing units short and simultaneously achieving a certain level of system availability. Solution algorithms are derived using the generalized Lagrange multiplier approach and marginal analysis approach. Sample data and output results are provided and sensitivity analysis is performed as the level of system availability changes in order to decide the optimal number of spares and availability in terms of economic sense.

• 한국국방경영분석학회지
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• 제7권2호
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• pp.43-62
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• 1981

Computational expressions for point availability and average availability of a system of components each of which is subject to random failures and has random restoration times are determined. Each component is assumed to have a fixed number of spares such that where all spares are exhausted no restoration can take place. These expressions are useful in deciding PL and ASL in the military logistic applications. Given a fixed length of mission duration and finite number of spares, a system may not be available at the end of a mission due to lack of spares. The probability distribution of system down time due to lack of spares is determined as a function of number of spares and mission duration.

• 한국경영과학회지
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• 제14권1호
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• pp.27-35
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• 1989

An algorithm that searches the general AND-OR graph is proposed. The convergence and the efficiency of the algorithm is examined and compared with an existing algorithm for the AND-OR graph. It is proved that the proposed algorithm is superior to the existing method both in the quality of the solution and the number of node expansions.

• 한국경영과학회지
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• 제34권4호
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• pp.43-56
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• 2009

In korean peninsular, aircraft defense with SAM (Surface-to-Air Missile) is very important because of short range of combat space in depth. Effective and successful defense operation largely depends on two factors, SAM's location and the number of SAM for each target based on missile's availability in each SAM's location. However, most previous papers have handled only the former. In this paper, we developed Set covering model which can handle both factors simultaneously and Multi-heuristic algorithm for solving allocation problem of the batteries and missile assignment problem in each battery. Genetic algorithm is used to decide optimal location of the batteries. To determine the number of SAM, a heuristic algorithm is applied for solving missile assignment problem. If the proposed model is applied to allocation of SAM, it will improve the effectiveness of air defense operations.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1998년도 추계학술대회 논문집
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• pp.182-185
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• 1998

In the two-tier CDMA cellular system with microcells and overlaying macrocells, slow-moving mobile user are assigned to microcells and those who move fast are assigned to overlaying macrocells in order to minimize the total number of handoffs. With this consideration the problem is how to find the thresholds by which the system distinguishes fast-moving user from those who move slowly based on the estimated speed of users. In this paper, two methods for the mobile speed estimation are proposed and two operations schemes for micro-macro cellular CDMA system are suggested. Based on these, Optimization models to find the optimal thresholds for micro-macrocell selection, which are subject to the constrains of QoS, are developed in view of minimizing the weighted total number of handoffs. And then algorithms to find optimal solutions of the models are devised.

• 한국시뮬레이션학회논문지
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• 제8권4호
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• pp.61-72
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• 1999

This paper presents an estimation method of container handling capacity and selection of resource allocation strategies of container terminals using the computer simulation models. Simulation models are developed to model container terminal consisting of 4 berths considering the berth allocation strategies, crane allocation strategies and the total number of container cranes using Arena simulation package. The proposed models do not consider the yard operations and gate operations. All the input parameters for the models are estimated on the basis of the existing container terminal operation data and the planning data for the automated container terminal planned by Korean government. Four berth allocation strategies and three crane allocation strategies are considered. The total number of container cranes considered ranges from 12 to 15. Non-terminating simulation techniques are utilized for the performance comparison among alternatives. The performance measures such as average ship turnaround time, average ship waiting time, average ship service time, the number of containers handled per year, and the number of ships processed per year are used. The result shows that the berth allocation strategy minimizing the sum of the number of ships waiting, the number of busy container cranes and number of ships handled performs better than any other berth allocation strategies. In addition, the crane allocation strategy allocating up to 5 container cranes per berth performs better than any other crane allocation strategies. Finally there are no significant performance differences among the alternatives consisting of different total number of container cranes allocated.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2006년도 추계학술대회
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• pp.284-287
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• 2006

We consider the transportation problem of optimizing the use of trailers and tractors. Several variants with fixed loading and unloading time are discussed. We show that the variant requiring on-time delivery can be solved in polynomial time, whereas the other variant requiring time-window delivery is NP-hard. We also discuss that if the number of loading and unloading operations assigned to each trailer or tractor is limited, even the variant requiring on-time delivery becomes NP-hard.

• 한국통신학회논문지
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• 제34권12B호
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• pp.1418-1425
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• 2009

본 논문은 플래쉬 메모리 접근시 erase 횟수를 줄이기 위하여 섹터 매핑 기법을 적용한 FTL (Flash Translation Layer) 알고리듬을 제안한다. 블록 매핑 기법을 적용한 기존의 알고리듬에 비하여 제안한 알고리듬은 섹터 단위의 매핑 테이블을 활용하여 데이터를 억세스하는 섹터 매핑 기법을 사용하여 erase 횟수를 줄임으로써 전체적인 메모리 억세스 시간을 줄이고 플래쉬 메모리의 수명을 연장시킬 수 있다. 제안한 알고리듬에서는 write를 위한 빈 공간이 없을 때 erase 횟수가 가장 적은 블록을 victim 블록으로 선택함으로써 wear-leveling을 구현하였다. 제안한 알고리듬을 검증하기 위하여 MP3 재생기, 동영상 재생기, 웹 브라우저, 문서 편집기의 어플리케이션에 대해 실험을 수행하였다. 제안한 알고리듬을 사용하였을 때 기존의 BAST, FAST 알고리듬과 비교하여 72.4%, 61.9%의 erase 횟수가 감소하였다.