• Geomechanics and Engineering
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• 제28권6호
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• pp.637-644
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• 2022

Loess soils are unsaturated and widely distributed in the northwest zone in China. Many steep slope of unsaturated are observed are observed to be naturally stable. However, a low factor of safety (FoS) for these slopes would be computed from the slope stability analysis following local code practices. It seems that the analyzed results following the local code practices do not agree with the real condition as observed in the field. It is commonly known that soil suction plays an important role in slope stability due to a higher shear strength of the unsaturated soil as compared with that of the saturated soil. In this paper, it is observed that the computed FoS can also be affected by unsaturated unit weight of the soil. However, the effect of unsaturated unit weight of the soil on the slope stability is commonly ignored in engineering practice. Therefore, both the effects of shear strength and unit weight of the unsaturated soil on the computed FoS of unsaturated soil slope are investigated in this study. It is observed that the unsaturated unit weight of soil on the computed FoS increases with increase in slope angle. It is also observed that the effects of the unsaturated shear strength and unsaturated unit weight on the computed FoS are more significant than the effect of 3D analyses compared to the 2D analyses on the FoS.

• 전기학회논문지
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• 제63권10호
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• pp.1467-1472
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• 2014

This paper study on powering characteristic on speed variation of propulsion system of prototype 8200 electric locomotive propulsion system through simulation modeling. For this purpose, it being applied in the field of railway IGBT (Insulated Gate Bipolar Transistor) elements are used. Converter was performed PLL (Phase-Locked Loop) control method that is used to control the phase and output voltage, and the inverter was carried an indirect vector control method to control the speed of traction motor. The results of simulation by modeling and experimental unit, we was confirmed that converter is controlled a unity power factor and output voltage by reference voltage. Also traction motor was controlled by indirect vector control and SVPWM inverter switching method very well.

• Nuclear Engineering and Technology
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• 제15권4호
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• pp.236-247
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• 1983

한국원자력 1호기(KNU-1)의 설계 및 운전자료를 이용하여 가압경수로 운전변수들의 변화에 대한 DNBR의 민감도를 분석하였다. 본 민감도 분석에는 원자로 출력, 압력, 냉각수 주입유량, 냉각수 주입온도, 반경방향 및 축방향 출력분포 그리고 축방향 출력편차 등의 운전변수가 고려되었다. 민감도 분석을 위하여는 노심의 열수력 해석용 전산코드인 COBRA-IV-K를 사용하였는데 본 코드는 COBRA-IV-i의 수정판으로써 한국에너지연구소에서 일부 프로그램을 수정하였고 또한 신뢰도도 확인하였다. 민감도 분석을 수행하기 전에 KNU-1 원자로심의 설계 및 운전조건을 근거로 하여 기초 계산을 수행하고 이 결과를 본 민감도 분석의 기본자료로 삼았다. 민감도 분석결과 원자로의 DNBR 열설계에 있어서 가장 민감한 운전변수는 냉각수 주입온도이고 가장 둔감한 변수는 축방향 출력분포라는 것이 밝혀졌다.

• Nuclear Engineering and Technology
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• 제29권1호
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• pp.78-84
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• 1997

The specific purpose of this study is to develop the numerical guide for the cost-benefit analysis of ORE ($/person-Sv reduction) to meet the criterion of ALARA in the design stage of the KNGR. In deriving the guide, the risk factor which is defined by the risk to unit collective radiation exposure dose (deaths/person-Sv) and the monetary value of human life ($/death) are required. The risk factor has been estimated from various clinical data accumulated for a number of years and continuously modified. And the monetary value of human life is usually quantified using the human capital approach. In this study, the risk to radiation exposure perceived by a group of people is investigated through an extensive poll survey conducted among university students in order to modify the existing risk factor for radiation exposure. And in evaluating the monetary value of human life, the QOL factor is introduced in order to incorporate the degree of public welfare or quality of life. As a result of study, a value within the range of 151, 000~172, 000 dollars per person-Sv reduction is recommended as the appropriate interim numerical guide for cost-benefit analysis of ORE to meet the criterion of ALARA in the design stage of the KNGR. A poll survey was also conducted in order to see whether the public acceptance cost of nuclear power should be incorporated in developing the guide, and the result of study shooed that such a cost does not need to be considered.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권3호
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• pp.387-400
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• 2017

A new junction-splitting based SAR ADC with a redundant searching capacitor array structure in $0.13{\mu}m$ CMOS process to alleviate capacitor mismatch effects, is presented. The normalized average power has a factor of 0.35 to the conventional SAR ADC at 10-bit conversion accuracy. Statistical experiments show the number of missing codes resulting from the mismatch reduces by 95% for 3% unit-capacitor mismatch ratio, while keeping the conversion energy to that of the conventional JS capacitor array.

• Korean Journal of Hydrosciences
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• 제3권
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• pp.81-96
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• 1992

This study represents the methodology for feasibility analysis of small hydro power SHP plant. Cumulative density function of Weibull distribution and Thiessen method were adopted to decide flow duration curve at SHP candidate site. The perfomance prediction model and construction cost estimation model for tunnel-type SHP plant were developed. Eight tunnel -type SHP candidate sites existing on Han-river were selected and surveyed for actual site reconnaissance. The performance characteristics and economical feasibility for these sites were analyzed by using developed models. As a result, it was found that the optimum design flowrate with the lowest unit generation cost for tunel-type SHP candidate site were the flowrate concerming with between 20% and 30% of time ratio on the flow duration curve. Additionally, primary design specifications such as design flowrate, effective head, capacity, annual averageload factor, annual electricity production were estimated and discussed for eight surveyed SHP candidate sites.

• 한국신뢰성학회지:신뢰성응용연구
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• 제11권1호
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• pp.59-81
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• 2011

Six Sigma has been disseminated into a variety of areas. It is believed that a stepwise understanding of Six Sigma's DMAIC is required for successes of unit projects. Meanwhile, infra-structure factors, such as leadership, organization, personnel management, educational system, etc., are also important to safely implant the Six Sigma into the whole enterprise and to thoroughly create the culture of innovation and enterprise. Careful analysis of those elements makes it possible to draw common connection between Project Management and the Six Sigma. This study drives the success elements for the successful adoption of the Six Sigma in the Korea Western Power Co., Ltd., of which management was evaluated as one of the tops based on the results of 2007 Management Innovation Assessment and arranges the similarity of like this factor and Enterprise Project Management. The results of this study are expected to provide a useful guideline for the adoption of the Six Sigma in whole company level.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.89-91
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• 1999

The use of electronic power unit essentially result in serious problems by harmonics. To reduce the effect by harmonics, we propose passive filter system which can control each harmonic filters individually. So, additional devices to detect and analyze harmonics were installed to filter system. According to measured data in the field, we calculated the values of filter components and verified them by computer simulation. After installation of filter system in the field, we could reduce harmonics and improve power factor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.277-279
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• 2002

Recently, power requirement has been increasing. But the large generation unit is hardly installed because of economic and environment problem. Therefore, the concern for DG(distributed generation) is growing. Present, allowable interconnection capacity of DG for composite distributed generation is studied. In this paper, it is studied that the new interconnection capacity of DG for composite distribution system interconnected DG. We study new allowable interconnection capacity by power factor and placement. We study SERV(sending end reference voltage) variation and allowable interconnection capacity interconnected new DG.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.361-364
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• 2011

In this paper, This work demonstrates a experimental evaluation for vehicle road noise NVH performance from the component-level NVH measurements of Tire. The power unit noise from tire emitted by cars has been reduced. It has been found that tire noise dominates noise produced by the power train when vehicles are driven at high constant speed. Therefore tire pattern noise is affected by pattern and vehicle and transmission loss. Tire noise mechanism is generated by several mechanisms. The sound of tire can propagate either through the air or through the structure of vehicle. Pattern noise is the result of pressure variations through the air to the interior side of vehicle. Especially, smooth asphalt, the periodicity of tread design, groove depth is important factor, which have an influence on the reduction of tire pattern noise.