• 한국건설관리학회논문집
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• 제19권5호
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• pp.81-89
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• 2018

본 연구의 목적은 플랜트 건설사업에서 모듈러 공법의 적용이 확대됨에 따라 모듈러 플랜트에 대한 업무특성을 고려하여 위험을 평가하고 위험에 대응하기 위한 예비비를 예측하는 것이다. 연구방법은 모듈러 플랜트의 업무특성을 고려하여 위험의 영향을 평가하기 위한 모델(방법)과 예비비를 예측하기 위한 모델(방법)을 제시한다. 그리고 제시된 모델을 기반으로 모듈러 플랜트 건설사업 1곳을 사례로 선정하여 위험요인의 영향을 평가하고 예비비를 예측한다. 상기와 같은 목적과 방법에 따라 도출된 결과는 다음과 같다. 위험요인의 발생확률과 영향점수를 평가하여 중요 위험요인 15개를 선정하였다. 그리고 모듈러 플랜트의 특성을 고려하기 위하여 설계(E), 구매(P), 제작(F), 운송(T), 시공(C)단계로 업무를 분류하여 예측된 예비비는 기초사업비(610,503,596 천원) 대비 약 6.739%이며, 설계(E) 2.850%, 구매(P) 6.225%, 제작(F) 6.211%, 운송(T) 4.165%, 시공(C) 8.168%로 도출되었다. 본 모델은 위험관리를 위한 의사결정 과정에서 정량적인 결과를 도출하는 방법으로 활용된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.184-188
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• 1989

This paper presents a fast realistic method based on a P-Q decoupled linearized model for contingency analysis. This method involves new idea to correct the errors caused by neglecting the resistance of transmission lines and/or by linearizing the model. The idea is to use fast correction method of errors by the principle of superposition for compensating these errors. Results demonstrating the effectiveness of the method on 25-bus model system and IEEE30-model system are presented

• Journal of the Korean Data and Information Science Society
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• 제26권6호
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• pp.1547-1555
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• 2015

We study the problem of nonignorable nonresponse in a two-way contingency table and there may be one or two missing categories. We describe a nonignorable nonresponse model for the analysis of two-way categorical table. One approach to analyze these data is to construct several tables (one complete and the others incomplete). There are nonidentifiable parameters in incomplete tables. We describe a hierarchical Bayesian model to analyze two-way categorical data. We use a nonignorable nonresponse model with Bayesian uncertainty analysis by placing priors in nonidentifiable parameters instead of a sensitivity analysis for nonidentifiable parameters. To reduce the effects of nonidentifiable parameters, we project the parameters to a lower dimensional space and we allow the reduced set of parameters to share a common distribution. We use the griddy Gibbs sampler to fit our models and compute DIC and BPP for model diagnostics. We illustrate our method using data from NHANES III data to obtain the finite population proportions.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.541-548
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• 2017

An increasing concern is paid to short-term voltage stability with the growth of penetration of induction motor loads. Reactive power reserve(RPR) of power system is critical to improve voltage stability. A definition of short-term voltage stability-related RPR(SVRPR) is proposed. Generators vary their contributions to voltage stability with their location and system condition, etc. Voltage support coefficient based on the second-order trace sensitivity method is proposed to evaluate SVRPR's contribution to short-term voltage stability. The evaluation method can account for the generator's reactive support in transient process and the contingency severity. Then an optimization model to improve short-term voltage stability is built. To deal with multiple contingencies, contingency weight taking into account both its probability and severity is proposed. The optimization problem is solved by primal dual interior point method. Testing on IEEE_39 bus system, it is indicated that the method proposed is effective. Short-term voltage stability is improved significantly by the way of SVRPR optimization. Hence, the approach can be used to prevent the happening of voltage collapse during system's contingency.

• Journal of the Korean Data and Information Science Society
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• 제28권6호
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• pp.1547-1555
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• 2017

This paper studies Bayesian test of homogeneity in contingency tables made by discretizing a continuous variable. Sometimes when we are considering events of interest in small area setup, we can think of discretization approaches about the continuous variable. If we properly discretize the continuous variable, we can find invisible relationships between areas (groups) and a continuous variable of interest. The proper discretization of the continuous variable can support the alternative hypothesis of the homogeneity test in contingency tables even if the null hypothesis was not rejected through k-sample tests involving one-way ANOVA. In other words, the proportions of variables with a particular level can vary from group to group by the discretization. If we discretize the the continuous variable, it can be treated as an analysis of the contingency table. In this case, the chi-squared test is the most commonly employed method. However, further discretization gives rise to more cells in the table. As a result, the count in the cells becomes smaller and the accuracy of the test becomes lower. To prevent this, we can consider the Bayesian approach and apply it to the setup of the homogeneity test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.209-210
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• 2011

This paper proposed protective coordination on HTS(High Temperature Superconducting) cable on 22.9kV distributed system. HTS cable transient model is developed and tested using EMTP-RV, system protective coordination is studied with ETAP. Possible contingency and protective scheme are considered real distribution system in Icheon substation. The simulation results was showed, in protective case to apply conventional relay, that appeared problem on HTS cable inner part. The HTS cable couldn't protection on contingency state of power system. It was using high-speed relay system instead of conventional relay system. Then, the HTS cable was protected contingency by circuit breaker.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1042-1045
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• 1999

This paper presents a new method for contingency selection of the transient stability. Contingency ranking in transient stability is done by estimating the change in the imaginary part of electro-mechanical oscillation mode, which represents modal synchronizing coefficient. And the change in the imaginary part is obtained by applying eigen-sensitivity theory of augmented matrix to linear system model. The Proposed algorithm was tested for New England System and compared the results with PSS/E dynamic simulation.

• Journal of the Korean Data and Information Science Society
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• 제28권1호
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• pp.207-215
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• 2017

In this paper we study pooling effects in Bayesian testing procedures of independence for contingency tables from small areas. In small area estimation setup, we typically use a hierarchical Bayesian model for borrowing strength across small areas. This techniques of borrowing strength in small area estimation is used to construct a Bayes test of independence for contingency tables from small areas. In specific, we consider the methods of direct or indirect pooling in multinomial models through Dirichlet priors. We use the Bayes factor (or equivalently the ratio of the marginal likelihoods) to construct the Bayes test, and the marginal density is obtained by integrating the joint density function over all parameters. The Bayes test is computed by performing a Monte Carlo integration based on the method proposed by Nandram and Kim (2002).

• Asia pacific journal of information systems
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• 제5권2호
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• pp.177-197
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• 1995

In a study involving 52 large organizations in the savings institutions industry, the relationship between information systems technology (IST) structure and competitive strategy was investigated based on structural contingency theory. Structural contingency theory argues that organizational performance is contingent on the congruence between structure and contingent factors. Competitive strategy is considered to be the most important contingent factor among organizational context variables. Two dimensions of IST structure and three types of competitive strategy were employed to test a contingency model. It was found that enhanced congruence between IST structure and competitive strategy was associated with higher competitive advantage. The structural dimension significantly associated with the "defender" strategic stance was more centralized and more integrated application of IST, while the structural dimension significantly associated with "prospector" positioning was more decentralized and less integrated application of IST.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.193-196
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• 1999

This paper presents a new systematic contingency selection and screening method for transient stability. The variation of modal synchronizing torque coefficient(MSTC) is computed using eigen-sensitivity analysis of the electromechanical oscillation modes in small signal stability model and contingencies are ranked in decreasing order of the sensitivities of the MSTC(SMSTC). The relevant clusters are identified using the eigenvector or participating factor. The proposed algorithm is tested on the KEPCO system. Ranking obtained by the SMSTC is consistent with the time simulation results by PSS/E.