• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.894-903
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• 2019

An approach for collapse risk assessment is proposed to evaluate the vulnerability of electric cabinet in nuclear power plants. The lognormal approaches, namely maximum likelihood estimation and linear regression, are introduced to establish the fragility curves. These two fragility analyses are applied for the numerical models of cabinets considering various boundary conditions, which are expressed by representing restrained and anchored models at the base. The models have been built and verified using the system identification (SI) technique. The fundamental frequency of the electric cabinet is sensitive because of many attached devices. To bypass this complex problem, the average spectral acceleration $S_{\bar{a}}$ in the range of period that cover the first mode period is chosen as an intensity measure on the fragility function. The nonlinear time history analyses for cabinet are conducted using a suite of 40 ground motions. The obtained curves with different approaches are compared, and the variability of risk assessment is evaluated for restrained and anchored models. The fragility curves obtained for anchored model are found to be closer each other, compared to the fragility curves for restrained model. It is also found that the support boundary conditions played a significant role in acceleration response of cabinet.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.2
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• pp.139-150
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• 2008

Recently, financial institutes and industrial companies are adopted to security token such as OTP, smart card, and USB authentication token and so on for secure system management and user authentication. However, some research institutes have been introduced security weaknesses and problems in security tokens. Therefore, in this paper, we analyses of security functions and security requirements in security token performed by analyses of standardization documents, trends, security problems, attack methods for security tokens. Finally, we propose a CC v.3.1 based security token protection profile.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.5
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• pp.271-277
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• 2020

Recoverability and vulnerability of navy ships under underwater explosion are critical verification factors in the acquisition phase of navy ships. This paper aims to establish numerical analysis techniques for the underwater explosion of navy ships. Doubly Asymptotic Approach (DAA) Equation of Motion (EOM) of primary shock wave and secondary bubble pulse proposed by Geers-Hunter was introduced. Assuming a non-compressive fluid, reference solution of the DAA EOM of Geers-Hunter using Runge-Kutta method was derived for the secondary bubble pulse phase with an assumed charge conditions. Convergence analyses to determine fluid element size were performed, suggesting that the minimum fluid element size for underwater explosion analysis was 0.1 m. The spherical and cylindrical fluid domains were found to be appropriate for the underwater explosion analyses from the fluid domain shape study. Because the element size of 0.1 m was too small to be applied to the actual navy ships, a very slender beam with the square solid section was selected for the study of fluid domain existence effect. The two underwater explosion models with/without fluid domain provided very similar results in terms of the displacement and stress processes.

• Structural Engineering and Mechanics
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• v.39 no.3
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• pp.411-425
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• 2011

This paper illustrates the results of a seismic vulnerability study aimed to derive the fragility curves for typical Algerian reinforced concrete bridge piers using an analytical approach. Fragility curves express the probability of exceeding a certain damage state for a given ground motion intensity (e.g., PGA). In this respect, a set of 41 worldwide accelerometer records from which, 21 Algerian strong motion records are included, have been used in a non-linear dynamic response analyses to assess the damage indices expressed in terms of the bridge displacement ductility, the ultimate ductility, the cyclic loading factor and the cumulative energy ductility. Combining the damage indices defined for 5 damage rank with the ground motion indices, the fragility curves for the bridge piers were derived assuming a lognormal distribution.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.790-793
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• 2007

유비쿼터스 환경 구축에 필수적인 IP의 고갈은 이미 심각한 문제로 대두된지 오래며, IPv6의 도입 연구 및 시범적용이 활발이 진행되고 있어 거의 무한에 가까운 IP로 희망에 가득찬 u-Korea 건설을 목표로 순차적인 진행 단계에 있으나, 기존 IPv4 체계에서 IPv6 환경으로의 전환 및 프로토콜 스펙 변경으로 인한 보안에 대한 필요성 또한 증대되고 있다. 본 고에서는 IPv6 환경의 보안 취약성 및 이에 대한 대응방안의 분석을 통하여 이러한 보안 문제를 해결하기 위한 해법을 살펴보고자 한다.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.81-86
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• 2000

In recent modern protective systems have been introduced to reduce the vulnerability of bridges to seismic events. These protective systems include base isolation devices of different types, damping devices and active control devices. The objective of this study is to analytically evaluate the efficiency of a seismic retrofit scheme using base isolation systems, such as lead rubber bearings and sliding isolators. In this study, a triaxial model was used, which is capable of accurately developing the behavior of sliding isolators including the influence of the changing vertical force and velocity on the friction coefficients. Seismic response analyses of the bridge before and after retrofit were carried out by using a three-dimensional nonlinear seismic analysis program, IDARC-BRIDGE. To evaluate the efficiency of a retrofit scheme using triaxial isolators, a comparative study of performances of above two base isolation systems was conducted, and the numerical results show that the triaxial isolation solution can effectively reduce the sheat forces at the piers for the vertical ground motion.

• Journal of Korean Society for Quality Management
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• v.19 no.2
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• pp.96-107
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• 1991

At the design stage of a plant, the plausible causes and pathways of release of hazardous materials are not clearly known. Thus there exist large amount of uncertainties on the consequences resulting from the operation of a fusion plant. In order to better handle such uncertain circumstances, we utilize the Probabilistic Risk Assessment(PRA) for the safety analyses on fusion power plant. In this paper, we concentrate on the tritium release accident. We develop a simple model that describes the process and flow of tritium, by which we figure out the locations of tritium inventory and their vulnerability. We construct event tree models that lead to various levels of tritium release from abnormal initiating events. Branch parameters on the event tree are assessed from the fault tree analysis. Based on the event tree models we construct influence diagram models which are more useful for the parameter updating and analysis. We briefly discuss the parameter updating scheme, and finally develop the methodology to obtain the predictive distribution of consequences resulting from the operating a fusion power plant. We also discuss the way to utilize the results of testing on sub-systems to reduce the uncertain ties on over all system.

• Structural Engineering and Mechanics
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• v.41 no.4
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• pp.527-538
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• 2012

In seismic analyses of structures, additional eccentricity is introduced to take account for oscillations of random and unknown origins. In many codes of practice, the torsion about the vertical axis is considered through empirical accidental eccentricity formulation. Due to the random nature of structural systems, it is very difficult to evaluate the accidental eccentricity in a deterministic way and to specify its effect on the overall seismic response of structures. The aim of this study is to develop a procedure for the evaluation of the accidental eccentricity induced by uncertainties in stiffness and mass of structural members, using the neural network techniques coupled with Monte Carlo simulations. This method gives very interesting results for single story structures. For real structures, this method can be used as a tool to determine the accidental eccentricity in the seismic vulnerability studies of buildings.

• Journal of the Korean Home Economics Association
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• v.34 no.4
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• pp.161-174
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• 1996

The purpose of the study is to investigate how childhood attachment and autonomy explain the gender differences in adulthood heterosexual love styles. The study examines (1) the gender differences in childhood attachment and autonomy and adulthood heterosexual love relationships, (2) the relationship between childhood attachment and autonomy in relation to mother, and love styles in adulthood among men and women. 405 married or unmarried men and women participated in a questionnaire study. Such statistic analyses are engaged for this study as cross-tabulation analysis, and one-way ANOVA. The key findings of the study are that the relationships of childhood developmental pattern of attachment and autonomy to adulthood heterosexual love styles differ between men and women. That is, developmental patterns of childhood attachment and autonomy to mother operate as a vulnerability factor in establishing adulthood love relationship, whereas childhood experiences do not explain adulthood love among women. These gender differences are discussed in theoretical contexts which explain gender-differentiated process of separation from mother during childhood.

• Journal of the Korean Home Economics Association
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• v.46 no.1
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• pp.73-86
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• 2008

The purpose of this study was to investigate the personal traits of children's characteristics as well as those of mothers' on the children's maladjustment behaviors. The study subjects were 345 preschooler-mother pairs. Results revealed that boys exhibited more maladjustment behaviors than girls, as expected. The results of a three way ANOVA analyses indicated that the multiple interactive factors of the children's temperament, cognitive outcomes, and parenting attitudes significantly affected the children's maladjustment behaviors. This trend was only representative across the sample of boys. In this study, the interaction effects of negative parenting attitudes and the children's lower levels of cognitive development on the children's maladjustment capacity were accentuated among boys with temperamental vulnerability.