• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.46-52
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• 2017

Recently durability design based on deterministic or probabilistic method has been attempted since service life evaluation in RC(Reinforced Concrete) structure exposed to chloride attack is important. The deterministic durability design contains a reasonable method with time effect on surface chloride content and diffusion coefficient, however the probabilistic design procedure has no consideration of time effect on both. In the paper, a technique on PDF(Probability of Durability Failure) evaluation is proposed considering time effect on diffusion and surface chloride content through equivalent surface chloride content which has same induced chloride content within a given period and cover depth. With varying period to built-up from 10 to 30 years and maximum surface chloride content from $5.0kg/m^3$ to $10.0kg/m^3$, the changing PDF and the related service life are derived. The proposed method can be reasonably applied to actual durability design with preventing conservative design parameters and considering the same analysis conditions of the deterministic method.

• Review of KIISC
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• v.31 no.5
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• pp.21-31
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• 2021

컴퓨터 기술의 발전에 따라 ML(Machine Learning) 및 AI(Artificial Intelligence)의 도입이 활발히 진행되고 있으며, 정보보호 분야에서도 활용이 증가하고 있는 추세이다. 그러나 이러한 모델들은 black-box 특성을 가지고 있으므로 의사결정 과정을 이해하기 어렵다. 특히, 오탐지 리스크가 큰 정보보호 환경에서 이러한 문제점은 AI 기술을 널리 활용하는데 상당한 장애로 작용한다. 이를 해결하기 위해 XAI(eXplainable Artificial Intelligence) 방법론에 대한 연구가 주목받고 있다. XAI는 예측의 해석이 어려운 AI의 문제점을 보완하기 위해 등장한 방법으로 AI의 학습 과정을 투명하게 보여줄 수 있으며, 예측에 대한 신뢰성을 제공할 수 있다. 본 논문에서는 이러한 XAI 기술의 개념 및 필요성, XAI 방법론의 정보보호 분야 적용 사례에 설명한다. 또한, XAI 평가 방법을 제시하며, XAI 방법론을 보안 시스템에 적용한 경우의 결과도 논의한다. XAI 기술은 AI 판단에 대한 사람 중심의 해석정보를 제공하여, 한정된 인력에 많은 분석데이터를 처리해야 하는 보안담당자들의 분석 및 의사결정 시간을 줄이는데 기여할 수 있을 것으로 예상된다.

• 대한예방의학회:학술대회논문집
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• 1993.10a
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• pp.153-154
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• 1993

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.185-185
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• 2011

기존 장대레일 궤도의 안정성 평가는 궤도 매개변수에 대하여 고정된 안전측의 값을 사용하는 결정론적인 해석에 의존해서 평가되어져 왔다. 그러나 실제현장의 궤도조건은 많은 영향인자들에 의해 그 특성이 불확실하게 변하고 있다. 따라서 온도하중에 의한 궤도 좌굴에 영향을 미치는 궤도 구성인자들의 불확실성 및 임의성을 보다 합리적으로 고려하기 위해서 확률론적 기법을 적용하는 것이 필수적이다. 본 연구에서는 기존 본 연구진에 의해 개발된 장대레일 궤도의 좌굴확률 평가시스템을 이용하여 좌굴 취약도 곡선을 나타내었으며, 궤도 좌굴에 영향을 미치는 주요변수 중 하나인 도상횡저항력에 대한 영향을 분석하였다. 좌굴확률 평가시스템에서는 장대레일 궤도의 좌굴확률을 산정하기 위하여 구조물의 안정과 파괴를 판단할 수 있는 기준을 한계상태방정식으로 표현하고, 이 한계상태방정식으로부터 확률론적 기법 중 하나인 AFOSM(Advanced First Order Second Moment) 방법을 이용하여 파괴확률의 간접적인 지표인 신뢰도지수(${\beta}$)를 통해 좌굴확률을 계산한다. 한계상태방정식에서 구조물의 강도(보유성능)에 해당하는 부분은 궤도의 허용좌굴온도이고, 하중(요구성능)에 해당하는 부분은 레일온도하중으로써 현재 레일온도와 중립온도의 차로 반영된다. 허용좌굴온도 산정에 고려되는 주요변수는 곡선반경(Radius), 도상횡저항력(Lateral Ballast Resista nce), 연직도상강성(Vertical Ballast Stiffness), 궤도 틀림량(Misalignment), 틀림길이(Half Wave Length), 열차운행속도(Velocity)이다. 각 확률변수들이 갖는 확률분포는 모두 정규분포로 가정하였다. 궤도의 기하학적 특성은 곡선반경 5,000m에 대해 고려하였으며, 열차는 KTX의 제원을 사용하여 정지된 상태에서 고려하였다. 틀림량과 틀림길이는 이에 대한 통계적 특성자료가 부족하여 확률변수로 고려하지 않고 결정론적 값으로 취급하였다. 레일온도의 통계적 특성치는 본 연구진에 의해 구축된 기후요소 및 레일온도 DB를 근거로 결정하였으며, 중립온도는 선로관리지침에 따라 $25{\pm}3^{\circ}C$를 기준으로 결정하였다. 또한 도상횡저항력은 실측 데이터를 참고로 하여 평균값에서 10%의 변동량을 갖는 것으로 보고 통계적 특성치를 결정하였다. 도상횡저항력이 좌굴확률에 미치는 영향을 매우 큰 것을 알 수 있었으며, 레일온도 $60^{\circ}C$일 때 도상횡저항력이 증가하면서 감소되는 좌굴확률이 도상저항력이 커질수록 그 감소량이 작아지는 것을 알 수 있었다.

• Nuclear Engineering and Technology
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• v.18 no.1
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• pp.38-47
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• 1986

A statistical procedure, which uses response surface method and Monte Carlo simulation technique, is proposed for analyzing the thermal margin of light water reactor core. The statistical thermal margin analysis method performs the best.estimate thermal margin evaluation by the probabilistic treatment of uncertainties of input parameters. This methodology is applied to KNU-1 core thermal margin analysis under the steady state nominal operating condition. Also discussed are the comparisons with conventional deterministic method and Improved Thermal Design Procedure of Westinghouse. It is deduced from this study that the response surface method is useful for performing the statistical thermal margin analysis and that thermal margin improvement is assured through this procedure.

• The Journal of the Korea Contents Association
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• v.19 no.7
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• pp.99-109
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• 2019

Data Envelopment Analysis (DEA), a non-parametric productivity analysis tool, has become an accepted approach for assessing efficiency in a wide range of fields. Despite of its extensive applications, some features of DEA remain bothersome. For example DEA is good at estimating "relative" efficiency of a DMU(Decision Making Unit), it only tells us how well we are doing compared with our peers but not compared with a "theoretical maximum." Thus, in order to measure efficiency of a new DMU, we have to develop entirely new DEA with the data of previously used DMUs. Also we cannot predict the efficiency level of the new DMU without another DEA analysis. We aim to show that DEA can be used to evaluate the efficiency of ports and suggest the methodology which overcomes the limitation of DEA through hybrid analysis utilizing DEA along with C5.0. We can generate classification rules C5.0 in order to classify any new Port without perturbing previously existing evaluation structures by proposed methodology.

• Investigative Magnetic Resonance Imaging
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• v.6 no.2
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• pp.137-146
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• 2002

Purpose : This paper introduces an improved classification approach which adopts a deterministic relaxation method and an agglomerative clustering technique for the classification of MRI using neural network. The proposed approach can solve the problems of convergency to local optima and computational burden caused by a large number of input patterns when a neural network is used for image classification. Materials and methods : Application of Hopfield neural network has been solving various optimization problems. However, major problem of mapping an image classification problem into a neural network is that network is opt to converge to local optima and its convergency toward the global solution with a standard stochastic relaxation spends much time. Therefore, to avoid local solutions and to achieve fast convergency toward a global optimization, we adopt MFA to a Hopfield network during the classification. MFA replaces the stochastic nature of simulated annealing method with a set of deterministic update rules that act on the average value of the variable. By minimizing averages, it is possible to converge to an equilibrium state considerably faster than standard simulated annealing method. Moreover, the proposed agglomerative clustering algorithm which determines the underlying clusters of the image provides initial input values of Hopfield neural network. Results : The proposed approach which uses agglomerative clustering and deterministic relaxation approach resolves the problem of local optimization and achieves fast convergency toward a global optimization when a neural network is used for MRI classification. Conclusion : In this paper, we introduce a new paradigm to classify MRI using clustering analysis and deterministic relaxation for neural network to improve the classification results.

• Journal of Convergence for Information Technology
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• v.9 no.6
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• pp.91-96
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• 2019

Recently, it is expected for requirement for more scientific research of weapon systems acquisition alternatives with reliability and objectivity. For these needs, study on methodology of weapon systems acquisition alternatives is but on-going, but it is still in its early stages and is unprofessional. We compared general decision making methods, government development program decision making methods, methodologies of weapon systems acquisition alternatives research such as AHP, ANP, KAAM and proposed AHP as weapon acquisition analysis. This study guarantees objectivity and derives scientific research results reliability by analyzing and comparing comprehensive elements such as cost, effectiveness, deployment schedule, program management risk. Further study on AHP weight and other decision making methods is needed considering category of weapon systems and program characteristics.

• Environmental and Resource Economics Review
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• v.19 no.1
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• pp.23-43
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• 2010

This article compares two different auction designs for $CO_2$ emission allowances, namely uniform pricing and multiple pricing, in view of market efficiency. Experimental economic method of Buckley et al. (2004) is applied in this analysis. As a result of this analysis as expected, multiple pricing method brings out Winner's curse. It means that uniform pricing method is more efficient than multiple pricing method.

• International Area Studies Review
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• v.14 no.2
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• pp.229-248
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• 2010

This study is intended to empirically investigate determinants of the degree of standardization vs. adaptation in global marketing programs for Korea firms. Our study has two main focuses. First, our study takes a global perspective instead of a binational, i. e., home vs. foreign perspective. Second, we accommodated two conflicting veiws - contingency and resource-based views in explaining determinants of global marketing strategy. As such determinants, we considered global market dynamism and complexity from a contingency view and global marketing assets from a resource-based view. Surveys were conducted with 128 Korean firms engaged in global marketing. Our study found that Korean firms with global assets tend to engage in highly standardized global marketing programs. On the other hand, global market dynamism and complexity did not show statistically significant relationships with the degree of standardization vs. adaptation. The findings suggest that a resource-based view may be more powerful than a contingency view in explaining global marketing strategies of Korean firms.