• 한국경영과학회지
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• 제27권3호
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• pp.145-156
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• 2002

Business managers are often required to use LP problems to deal with uncertainty inherent in decision making due to rapid changes in today＇s business environments. Uncertain parameters can be easily formulated in the two-stage stochastic LP problems. However, since solution methods are complex and time-consuming, a common approach has been to use modified formulations to provide upper and lower bounds on the two-stage stochastic LP problem. One approach is to use an expected value problem, which provides upper and lower bounds. Another approach is to use “walt-and-see” problem to provide upper and lower bounds. The objective of this paper is to propose a modified approach of “wait-and-see” problem to provide an upper bound and to compare the relative error of optimal value with various upper and lower bounds. A computing experiment is implemented to show the relative error of optimal value with various upper and lower bounds and computing times.

• 한국정보시스템학회지:정보시스템연구
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• 제9권1호
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• pp.235-255
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• 2000

Facing in very rapidly 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.

• 한국정보시스템학회:학술대회논문집
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• 한국정보시스템학회 2000년도 추계학술대회
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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.

• Communications for Statistical Applications and Methods
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• 제28권6호
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• pp.643-653
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• 2021

Few studies are found in literature on estimation of population quantiles using the method of ranked set sampling (RSS). The optimal RSS strategy is to select observations with at most two fixed rank order statistics from different ranked sets. In this paper, a near optimal unbalanced RSS model for estimating p^th(0 < p < 1) population quantile is proposed. Main advantage of this model is to use each rank order statistics and is distributionfree. The asymptotic relative efficiency (ARE) for balanced RSS, unbalanced optimal and proposed near-optimal methods are computed for different values of p. We also compared these AREs with respect to simple random sampling. The results show that proposed unbalanced RSS performs uniformly better than balanced RSS for all set sizes and is very close to the optimal RSS for large set sizes. For the practical utility, the near optimal unbalanced RSS is recommended for estimating the quantiles.

• 가정의학회지
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• 제39권6호
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• pp.333-339
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• 2018

Background: There is a distinction in alcohol consumption behavior between adults and college students. This study aims to verify the usability and the optimal cutoff point of Alcohol Use Disorders Identification Test-Korean revised version (AUDIT-KR) for screening alcohol use disorder in college students when the diagnostic and statistical manual of mental disorders (DSM), 5th edition diagnostic criteria is applied. Methods: A total of 922 college students living in Daejeon were enrolled and divided into two groups based on how many items they corresponded to among DSM-5 alcohol use disorder diagnostic criteria: those who corresponded to ${\geq}2$ of the 11 items were classified into the patient group (107 males, 89 females) while the others into the control group (311 males, 415 females). The participants were evaluated using AUDIT-KR to find the optimal cutoff point for screening alcohol use disorder, sensitivity, and specificity. Results: The mean${\pm}$standard deviation scores in the AUDIT-KR were $12.76{\pm}7.27$, $10.72{\pm}4.62$ for males and females, respectively, in the patient group. In contrast, in the control group the scores were $6.26{\pm}5.23$ and $3.95{\pm}3.59$ in males and females, respectively. The area under the receiver operating characteristic curve (95% confidence interval) regarding alcohol use disorder screening by AUDIT-KR was 0.768 (0.715-0.821) and 0.883 (0.848-0.919) for males and females, respectively. The optimal cutoff point of alcohol use disorder for males was >9, sensitivity 64.49%, and specificity 76.85%. The optimal cutoff point for females was >6, sensitivity 82.02%, and specificity 80.48%. Conclusion: This study suggested that AUDIT-KR can be used as a screening tool for alcohol use disorder in groups of college students when DSM-5 diagnosis criteria are applied.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.337-339
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• 2004

In this paper, we discuss optimal design of Fuzzy Polynomial Neural Networks by means of Genetic Algorithms(GAs). Proceeding the layer, this model creates the optimal network architecture through the selection and the elimination of nodes by itself. So, there is characteristic of flexibility. We use a triangle and a Gaussian-like membership function in premise part of rules and design the consequent structure by constant and regression polynomial (linear, quadratic and modified quadratic) function between input and output variables. GAs is applied to improve the performance with optimal input variables and number of input variables and order. To evaluate the performance of the GAs-based FPNNs, the models are experimented with the use of Medical Imaging System(MIS) data.

• 대한수학회논문집
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• 제12권3호
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• pp.531-538
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• 1997

In this paper, we show how to construct an optimal normal basis over finite field of high degree and compare two methods for fast operations in some finite field $GF(2^n)$. The first method is to use an optimal normal basis of $GF(2^n)$ over $GF(2)$. In case of n = st where s and t are relatively primes, the second method which regards the finite field $GF(2^n)$ as an extension field of $GF(2^s)$ and $GF(2^t)$ is to use an optimal normal basis of $GF(2^t)$ over $GF(2)$. In section 4, we tabulate implementation result of two methods.

• 응용통계연구
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• 제8권2호
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• pp.121-132
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• 1995

정상조건에서 수명이 상당히 긴 다수의 부품으로 구성된 직렬형 시스템의 수명검사를 현실적으로 수행하기 위해 부분적 단계충격 수명검사의 최적 검사계획에 관하여 고찰하였다. 시스템을 구성하고 있는 부품의 수명이 서로 독립인 지수분포를 따르는 것으로 가정하여 각 부품의 고장률과 가속인자의 최우추정량을 구하였다. 또한 각 부품의 고장률과 가속인자에 관한 최우추정량의 일반화 점근분산의 합과 각 부품의 가속인자에 관한 최우추정량의 점근분산의 합을 구하여 이를 최소가 되게 하는 최적변환시점의 결정방법을 제안하였다.

• 환경위생공학
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• 제18권3호통권49호
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• pp.11-20
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• 2003

There are two ways of reducing air pollution. One is the approach of the pollutant source control and the other one is the traffic demand decreasing approach. This study is focusing on the approach of land use planning and optimal location of urban facilities because those are the basic cause to generate transportation demands. So, the purpose of this study would be to analyze the changes of NOx and CO distribution on environmental air by functional hierarchy of urban roads and to make evaluation model of 'Transportation-Land Use -Air Pollution'. It will contribute to improve the air pollution level at same actual traffic generation according to different location.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.75-79
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• 2000

This paper proposes the optimal placement with minimum set of Phasor Measurement Units (PMU's) using tabu search and makes an alternative plan to secure the robustness of the network with PMU's. The optimal PMU Placement (OPP) problem is generally expressed as a combinatorial optimization problem subjected to the observability constraints. Thus, it is necessary to make a use of an efficient method in solving the OPP problem. In this paper, a tabu search based approach to solve efficiently this OPP problem proposed. The observability of the network with PMU's is fragile at any single PMU contingency. To overcome the fragility, an alternative scheme that makes efficient use of the existing measurement system in power system state estimation proposed. The performance of the proposed approach and the alternative scheme is evaluated with IEEE sample systems.