• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.217-227
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• 1992

The first and second-order reliability method(FORM and SORM) is presented using one dimensional finite difference and two dimensional finite element transport models. FORM and SORM can be used without any restrictive assumptions about the properties of the media, and the sensitivity information obtained as part of these analyses is used to identify the parameters which have major influence on the estimate of probability. The reliability analysis of transport in a one-dimensional domain is used to test the robustness of the reliability code and to evaluate the accuracy of the reliability method. A continuous source 2-D example with a concentration threshold limit state function is used to evaluate the influence of the parameters in the location of interest on the reliability solution.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.8
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• pp.813-822
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• 2010

Integrated data processing for display of flight critical data and mission critical data was conducted without additional display instruments using glass cockpit design. Based on a pre-designed flight critical system and a mission critical system, this paper shows an optimal design of subsystem integration. The design satisfies safety requirements of flight control systems(FCS) and requires minimized modification of pre-designed systems. By conducting integration test using System Integration laboratory(SIL), it is confirmed that the introduced design approach meets the safety requirements of the MEP system.

• Journal of the Korea Society for Simulation
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• v.16 no.1
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• pp.59-68
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• 2007

IT (Intrusion Tolerant) technology is for guaranteeing the availability of service for certain amount time against the attacks which couldn't be prevented by the currently deployed information security countermeasures. IT (Intrusion Tolerant) technology mainly makes use of the replication of service and system fur enhancing availability, and voting scheme and GMP (Croup Management Protocol) are used for the correctness of service. This paper presents a scheme to analyze dependability of IT (Intrusion Tolerant) technology through probabilistic and simulation method. Using suggested analysis scheme, we can analyze the robustness and make a sensible trade-offs in of IT (Intrusion Tolerant) technology.

• The Korean Journal of Applied Statistics
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• v.22 no.2
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• pp.261-270
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• 2009

Current financial crisis triggered by shaky U.S. banking system adds to the emphasis on the importance of the volatility in controlling and understanding financial time series data. The ARCH and GARCH models have been useful in analyzing economic time series volatilities. In particular, multivariate GARCH(MGARCH, for short) provides both volatilities and conditional correlations between several time series and these are in turn applied to computations of hedge-ratio and VaR. In this short article, we try to assess various MGARCH models with respect to the back-testing performances in VaR study. To this end, 14 korean stock prices are analyzed and it is found that MGARCH outperforms rolling window, and BEKK and CCC are relatively conservative in back-testing performance.

• Journal of KIISE:Software and Applications
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• v.29 no.12
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• pp.860-872
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• 2002

Fault tree analysis is the most widely used saftly analysis technique in industry. However, the analysis is often applied manually, and there is no systematic and automated approach available to validate the analysis result. In this paper, we demonstrate that a real-time model checker UPPAAL is useful in formally specifying the required behavior of safety-critical software and to validate the accuracy of manually constructed fault trees. Functional requirements for emergency shutdown software for a nuclear power plant, named Wolsung SDS2, are used as an example. Fault trees were initially developed by a group of graduate students who possess detailed knowledge of Wolsung SDS2 and are familiar with safety analysis techniques including fault tree analysis. Functional requirements were manually translated in timed automata format accepted by UPPAAL, and the model checking was applied using property specifications to evaluate the correctness of the fault trees. Our application demonstrated that UPPAAL was able to detect subtle flaws or ambiguities present in fault trees. Therefore, we conclude that the proposed approach is useful in augmenting fault tree analysis.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.6
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• pp.248-262
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• 2008

As the number of large size multimedia files increases and the importance of individual's digital data grows, storage devices have been advanced to store more data into smaller spaces. In such circumstances, a physical damage in a storage device can destroy large amount of important data. Therefore, it is needed to verify the robustness of various physical faults in storage device before certain systems are used. We developed SOAR(Storage Reliability Analyzer), Storage Reliability Analyzer, to detect physical faults in diverse kinds of HDD hardware components and to recover the systems from those faults. This is a useful tool to verify robustness and reliability of a disk. SOAR uses three unique methods of creating physical damages on a disk and two unique techniques to apply the same feature on file systems. In this paper, we have performed comprehensive tests to verify the robustness and reliability of storage device with SOAR, and from the verification result we could confirm SOAR is a very efficient tool.

• Geotechnical Engineering
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• v.13 no.1
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• pp.5-18
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• 1997

In order to make reliable ground shock predictions in saturated geological media, it is necessary to use multi -phase material models and numerical codes. This paper presents the results of theoretical study of the fundamental behavior of multi-phase porous media subjected to high dynanlic loadings, and deals with the development of numerical code MPDAP with JWL(Jones-Wilkins-Lee) model, which is capable of considering the kinds and characters of explosives. To check the global equilhorium equations of the numerical code, we carried out some verifications. In the cases of the elastic spherical wave propagation in a single phase medium, one-dimensional linear ronsolidation, and one timensional wave propagation in saturated linear elastic soils and rocks, the results calculated by MPDAP show close agreement with closed-form solutions or numerical solutions generated with two phase code.

• Fire Science and Engineering
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• v.26 no.2
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• pp.32-39
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• 2012

This research focuses on finding the way of improving creativity in fire stations by scrutinizing the factors influencing and enhancing creativity in organizations. As environmental changes including the needs of citizens as well as the climate change are moving culminated today, fire stations should be changed appropriately to get the legitimacy of existence not to mention their own mission accomplishments. In this respect, the creativity can be expected as the main factor for fire stations' going concern. This research provided 5 hypotheses to find whether the chosen factors such as vision, learning/unlearning and positive feedback affect the creativity in fire stations. To prove hypotheses are valid, we employed survey as a method in which 155 firemen in Seoul responded, ending up with getting the result that the vision formulation and sharing, unlearning activities and positive feedback improve organizational creativity. In conclusion, this paper suggests that fire stations establish useful policies for the creativity based on these research findings.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.261-274
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• 1999

Recently, automated business processing systems, so called workflow systems, have been studied. have been studied. even though each task has noticible duration inherently, most of previous models regard it as a simple finite automation where state transitions occur instantly. In this paper, we propose a modeling method for workflow each of whose component task has minimum processing time and due-date. Firstly we provide a priority function to choose the proper alternatives when tasks fail before their due-date. The priority function considers the time-relevant factor and the semantic compatibility level to decide the best alternative. secondly, we identify six different types of execution requirements for tasks with noticible durations. They are serial, parallel, simultaneous start simultaneous termination, interleaved and nested dependency. Note that previous models deal with only serial execution and parallel execution. Lastly, we also propose graph-based methods to detect logical conflicts in time constraint-based workflow specifications.

• The Korean Journal of Health Service Management
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• v.5 no.3
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• pp.25-39
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• 2011

본 연구는 병원 근로자들의 직무스트레스와 소진의 관계에 미치는 펀 리더십과 근로자 놀이성의 조절효과를 규명함으로써 향후 병원조직의 효과적인 인적자원관리에 필요한 기초자료를 제공하고자 하였다. 연구자료는 부산지역 2개 병원에 근무하는 근로자(의사 제외)를 대상으로 구조화된 자기기입식 설문지를 통하여 수집하였으며 총 230부의 설문지를 배부하여 이 중 207부의 설문을 회수하였다. 설문 문항에는 응답자의 일반적 특성, 직무스트레스 특성, 펀 리더십, 근로자 놀이성, 소진 등을 측정하는 항목들이 포함되었다. 자료 분석을 위해 SPSS WIN 18.0을 이용하여 빈도분석, 신뢰도분석, 상관관계분석과 조절회귀분석 등을 수행하였다. 주요 결과를 요약하면 다음과 같다. 첫째, 직무스트레스와 소진의 관계에서 펀 리더십은 직접 효과는 물론 조절효과도 유의하게 나타나지 않았다. 둘째, 직무스트레스와 소진의 관계에서 근로자 놀이성은 소진에 직접적인 효과를 주는 변수임과 동시에, 낮은 유의수준(p=0.053)에서지만 직무스트레스와의 상호작용을 통해 소진을 감소시키는 조절효과가 있는 것으로 나타났다. 본 연구는 병원 근로자의 업무 수행과 관련해 비교적 관심을 받지 못했던 펀 리더십이나 근로자 놀이성 등과 같은 성격적 특성이 소진을 감소시키는 유효한 조절변수가 될 수 있음을 검증해 보았다는 점에 그 의의가 있으며, 다만 후속 연구를 통해 추가적인 검증이 필요할 것으로 판단된다.