• 전기학회논문지
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• 제57권7호
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• pp.1123-1128
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• 2008

The necessity of online dynamic security assessment is getting apparent under Electricity Market environments, as operation of power system is exposed to more various operating conditions. For on-line dynamic security assessment, fast transient stability analysis tool is required for contingency selection. The TEF(Transient Energy Function) method is a good candidate for this purpose. The clustering of critical generators is crucial for the precise and fast calculation of energy margin. In this paper, we propose a new method for fast decision of mode of instability by using stability indices and energy margin. The method is a new version of our previous paper.[1] Case studies are showing very promising results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.134-136
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• 2002

In April of 2000, the Korea Power Exchange(KPX) was introduced into Korea electricity market. The purpose of this paper is to describe how the system operator indicates operational risks between the transmission planning and the supply and demand growth to make the market "work" and manage the power system in real time. This paper describes the experiences of kpx about the indication of operational risks including, for example, contingency analysis, voltage profile and fault capacity of three-phase short current.

• 한국경영과학회지
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• 제21권2호
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• pp.71-93
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• 1996

Selection of appropriate knowledge acquisition and representation techniques is regarded as a major task in the development of expert systems. This depends on the characteristics of problem domains. Expert system builders have often adopted a technique without a formal analysis of application domains. The purpose of this paper is to provide the best knowledge aquisition and representation technique for use in human resource management problem domains. In an attempt to meet this purpose, the conceptual contingency model that suggests the best technique according to managerial decision categories is used as a guidance. In order to determine the priority of managerial decision categories, the Analytic Hierarchy Process and an extended method are proposed.

• Communications for Statistical Applications and Methods
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• 제9권1호
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• pp.197-212
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• 2002

When assessing goodness-of-fit of a model, a small subset of deviating observations can give rise to a significant lack of fit. It is therefore important to identify such observations and to assess their effects on various aspects of analysis. A Cook's distance measure is usually used to detect influential observation. But it sometimes is not fully effective in identifying truly influential set of observations because there may exist masking or swamping effects. In this paper we confine our attention to influential subset In GLMs such as logistic regression models and loglinear models. We modify a backwards stepping algorithm, which was originally suggested for detecting outlying cells in contingency tables, to detect influential observations in GLMs. The algorithm consists of two steps, the identification step and the testing step. In identification step we Identify influential observations based on influencial measures such as Cook's distances. On the other hand in testing step we test the subset of identified observations to be significant or not Finally we explain the proposed method through two types of dataset related to logistic regression model and loglinear model, respectively.

• 농촌계획
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• 제8권1호
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• pp.94-104
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• 2002

In spite of the importance of the farm area in Seoul, in providing fresh vegetables, a pleasant environment and a good quality of life for residents, rapid urbanization and industrialization have greatly reduced the farm area. The purpose of this study is to examine farmers' intentions and attitudes to provide supporting data for planning the strategy of urban agricultural development. All the collected data was analyzed using the contingency tables and the Chi-square test using the SAS computer statistical package. Based on analysis of the survey data, the leaseholders were found to be more satisfied with their job than the landowning farmers. Also, the small-scale farmers with green houses showed greater job satisfaction than the ordinary large-scale farmers. Farmers' views on the farming in Seoul were different depending on their status. Therefore, agricultural strategies in there should be considered their different attitudes.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2006년도 춘계학술발표논문집
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• pp.502-505
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• 2006

인터넷 전자상거래는 점차 신무역라운드로 부상하고 있으며, 온라인 기업 중심으로 주목받던 e-비즈니스는 비용절감 및 기업의 효율성을 극대화하기 위해 정보기술을 도입하는 기존 기업 중심으로 재편되고 있고, e-비즈니스가 기업의 기본 전략으로 자리 잡고 있다. 본 논문에서는 차세대 전자상거래의 모습을 예측하기 위해 Drivers, Enablers, Mega-trends를 찾고, Contingency Analysis 등의 도구를 활용하여 유통업의 새로운 고객 만족을 위한 탐색 기회를 제공하면서, 기술 주도의 새로운 산업 분야로 대두될 수 있는 다양하고 자동화된 종합적인 서비스 제공 여부를 중심으로 차세대 전자상거래 모습을 예측해 보고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.239-242
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• 2001

This paper presents a windows program package for solving security constrained OPF in interconnected power systems, which is based on the combined application of evolutionary programming(EP) and sequential quadratic programming(SQP). The objective functions are the minimization of generation fuel costs and system power losses. The control variables are the active power of the generating units, the voltage magnitude of the generator, transformer tap settings and SVC setting. The state variables are the bus voltage magnitude, the reactive power of the generating unit, line flows and the tie line flow. In OPF considering security, the outages are selected by contingency ranking method. The resulting optimal operating point has to be feasible after outages such as any single line outage(respect of voltage magnitude, reactive power generation and power flow limits). The OPF package proposed is applied to 10 machines 39 buses model system.

• 산업공학
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• 제14권2호
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• pp.198-204
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• 2001

The ISO 9000 family of international quality management standards were revised on 15 December 2000. The ISO 9001:2000 standard is used for certification/registration and contractual purposes by organizations seeking recognition of their quality management system(QMS). We summarize key contents changed in ISO 9000:2000 family standards. To comply with ISO 9001:2000, we analyze the current QMS for steel outfit industry, using audit results from ISO 9001:1994 for seven steel outfit firms during last three years. We investigate statistical relationships between ISO 9001:2000 and ISO 9001:1994 requirements from a three dimensional contingency table with audit results. We observe that the importance of requirements of the ISO 9001:2000 sections makes a difference between companies.

• 한국안전학회지
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• 제11권3호
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• pp.89-96
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• 1996

This paper presents a study on the analysis and evaluation for ELF( Extremely Low Frequency) electric and magnetic fields under the transmission line according to the power system states. The power system states are classified into two types, normal state resulting from normal operation and alert state from outages. The current in a system is changed continually owing to the load fluctuations even in a normal operation. To calculate the current of the concerned line in a normal state, the system load level is devided into light, base and heavy load level. In case of contingency, an efficient algorithm based on matrix inversion lemma is developed to figure out the current changes. In order to analyze the variations of ELF field caused by the current fluctuations the electrostatic field approach which is far simpler than the electromagnetic field one based on Maxwell equation is introduced in this paper. The suggested method is applied to the IEEE 14 bus system to demonstrate the usefulness.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1999년도 KOBA 방송기술 워크샵 KOBA Broadcasting Technology Workshop
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• pp.43-48
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• 1999

To clarify the motion characteristics of free-style Okinawan dance“Kachaasi”, first the subjective impression was quantitatively evaluated with semantic differential technique to cluster its types. Then, the contingency of joint rotation in shoulder, elbow and wrist joints was examined with multivariate autoregressive model. The time-series data of positions and angels of three joints were calculated according to the deforming conditions and shielding directions of the ring lights. As the results, in an excellent dancer, the motions of shoulder and elbow were highly synchronized and smoothly controlled. The low-frequency output of the shoulder and elbow were mutually interacted. Meanwhile, the wrist behaved independently of other joints' rotation.