• 한국안전학회지
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• 제5권3호
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• pp.8-26
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• 1990

It is important to have exact information about the contact pressure distribution in the design of connected parts of machines and structures. In previous works, stress analyses on a two body contact problem have been carried out in large numbers. Besides, the measurement of contact stress is important to confirm the adequateness of the theoretical analysis, to verify appropriateness of Hertzian contact theory and to know the practical pressure distribution, but an excellent measuring method con't be found at present. Therefore, a quantitative measurement of contact pressure by means of ultrasonic waves using a normal probe and an angle has been proposed to measure the contact pressure distribution between two rough flat surfaces. At first, in a new proposed calibration method, the relation between mean contact pressure and sound pressure of reflected waves is obtained by using calibration blocks with various surface roughnesses made of the same material as the rectangular section beams And then, this experimental results are compared with the analytical ones, and the utility of this method is discussed.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2003년도 춘계학술발표논문집 (하)
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• pp.2045-2048
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• 2003

정보통신기술의 발전으로 유 무선 인터넷 사용자가 기하급수적으로 증가하고 있는 가운데 무선 인터넷을 이용한 m-Commerce 의 활성화가 기대되고 있다. 이와 더불어 무선 인터넷에서 안전한 m-Commerce를 제공하기 위해서는 다양한 모바일 기기 환경에 맞춘 무선 인터넷 PKI 서비스가 요구된다. 본 논문에서는 모바일 기기 성능, 네트워크 환경, 서비스 종류, 사용자의 보안 요구 사항에 맞추어 경제학 이론에서 출발한 MAUT(Multi-Attribute Utility Theory)와 간결한 휴리스틱스(Simple Heuristics) 알고리즘을 이용한 보안 등급 프로토콜을 동적으로 결정하는 적응적 보안 정책 알고리즘을 제안한다. 이를 바탕으로 PKI와 X9.59 기반의 보안 e/m-Commerce를 구축한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.113-115
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• 2003

The electric power industry throughout the world is undergoing considerable changes from the vertically integrated utility structure to the deregulated market. However, the deregulated electricity market is operated with respect to theory of economical efficiency, and therefore, the system operator requires data with fast contingency ranking for security of the bulk power system. This paper presents fast calculation method for determining contingency ranking using the weather dependant probabilistic risk index(PRI). The probabilistic risk index can be classified into normal weather and adverse weather. This paper proposes calculation method using the probabilistic risk index in determining contingency ranking requiring for security under the deregulated electricity market.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권2호
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• pp.246-253
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• 2013

The Modular Multilevel Converter (MMC) with full bridge cells is available for utility interactive inverter in high voltage line. When it is interconnected with power line, it is possible to control the active power flow in order to supply or charge the power in the line. This research applied the MMC to grid connection system of distributed generator and a power flow control for the MMC is investigated. Theory of power flow between the MMC and the power line is described and control method of power flow and capacitor voltages on arm cells for the MMC are proposed. And effectiveness of the proposed control method is presented by simulation.

• 대한안전경영과학회지
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• 제4권3호
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• pp.1-11
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• 2002

It has been Management for stabilize Enterprise-Management for Economic demand for to Productivity, Automation, customer satisfaction, Especially Semiconductor-Industry has been, potential-risk in working to factory to machine equipment, all kinds of utility, gas, chemical, electronic, Fire. This study of basic-purpose has Research Different From as Follow to analysis and Solution For semiconductor product Factory of a actual point Data and specific-gravity to Relation for company-Injury. 1. It has been try to Injury-Tendency and cause-Analysis for our County-Manufacture-Occupation. 2, Semiconductor Injury of Actual-condition in Enforcement for problem and Analysis that Injury Problem has occupated it Submitted to Solution for ordinary Injury theory View to point Solve at for New Model has applicated to that nilem for processed to Solution.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제24권3호
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• pp.777-792
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• 2010

경쟁력 있는 지식기반 사회를 구축하기 위해서 다양한 교수법을 구안하고자 하는 노력과 더불어 우리나라 현실에 맞는 교수법 구안 연구도 함께 진행되어야 할 필요성이 있다. 이에 따라 본고에서는 설명식 수업을 통하여 학생들이 수학을 이해하고 의미 있게 받아드리기 위한 방안으로 Ausubel의 유의미 학습을 재조명하였다. Ausubel의 유의미 학습의 의의와 조건 그리고 유의미 학습의 방법 등을 분석함으로써 수학교육에서 유의미 설명식 학습 활용이 보다 용이하게 활용될 수 있도록 하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1114-1116
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• 2003

Voltage sags are known as a serious problem causing mal-operation of equipment like computers, process controllers and adjustable-speed drives. In this paper, characterization of voltage sag and an overview of methods used in the mitigation of voltage sags are presented. Moreover a fast detection method for voltage disturbances is explored. The algorithm is based on the theory that allows a set of three-phase voltages be converted the d-q value. The utility input voltages are sensed and then converted to some quantities in the d-q transformation. And the difference between reference value and input value are showed that some disturbances happened in the system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.152-153
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• 2007

industrial site has led to a growing concern for harmonic distortion and the resulting impacts on system equipment and operation. Harmonic current is generated by the operation of non-linear load, it means that voltage and current waveforms exhibit a non-linear relationship. Harmonics cause increase losses in the customer and utility power system components. This paper describes application of instantaneous active and reactive theory for the compensation of harmonic currents in three-phase non-linear load.

• 산업공학
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• 제13권2호
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• pp.273-280
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• 2000

Time-tradeoff measures and healthy years equivalents were assessed and compared through an empirical study based on Multi-attribute utility theory. The study included 33 student subjects as a pilot study, and 54 end-stage renal disease patients in Wisconsin. The two outcome measures were compared with the survival duration of 1, 5, and 10 years. The results of the study show that the time-tradeoff method and the two-stage method did not lead to the same numerical quantities, although they aim to measure the same quantities (equivalent numbers of healthy years) theoretically. The healthy years equivalents involved more inconsistencies, and were less reliable than the time-tradeoff measures. Overestimation of the healthy years equivalents was observed. This seemed to be caused by the complex procedure of the two-stage method as well as by the preferences assessment biases. Based on the study experiences, the time-tradeoff measure would be recommended for problems involving generic medical applications and health policies.

• Structural Engineering and Mechanics
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• 제69권2호
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• pp.121-129
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• 2019

The present study investigates the propagation of shear waves in a composite structure comprised of imperfectly bonded piezoelectric layer with a micropolar half space. Piezoelectric layer is considered to be initially stressed. Micropolar theory of elasticity has been employed which is most suitable to explain the size effects on small length scale. The general dispersion equations for the existence of waves in the coupled structure are obtained analytically in the closed form. Some particular cases have been discussed and in one particular case the dispersion relation is in well agreement to the classical-Love wave equation. The effects of various parameters viz. initial stress, interfacial imperfection and micropolarity on the phase velocity are obtained for electrically open and mechanically free system. Numerical computations are carried out and results are depicted graphically to illustrate the utility of the problem. The phase velocity of the shear waves is found to be influenced by initial stress, interface imperfection and the presence of micropolarity in the elastic half space. The theoretical results obtained are useful for the design of high performance surface acoustic devices.