• 한국공작기계학회논문집
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• 제17권3호
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• pp.8-13
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• 2008

The paper proposes a model-based measurement of unsteady flow rate by using distributed parameter pipeline model and the measured pressure values at two distant points along the pipeline. The distributed parameter model of hydraulic pipeline is applied with consideration of frequency dependent viscosity friction and unsteady velocity distribution at a cross section of a pipeline. By using the self-diagnostics functions of the measurement method, the validity is investigated by comparison with the measured and estimated pressure and flow rate wave forms at the halfway section on the pipeline. The results show good agreement between the estimated flow rate wave forms and theoretical those under unsteady laminar flow conditions. The method proposed here is useful in estimating unsteady flow rate through an arbitrary cross section in hydraulic pipeline and components without installing an instantaneous flowmeter.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.179-179
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• 2012

Low pressure radio-frequency glow discharges are investigated using theoretical modeling and various experimental diagnostic methods. In the calculations, global models and transformer models are developed to understand the chemical kinetics as well as the electrical properties such as the effective collision frequency, the heating mechanism and the power transferred to the plasma electrons. In addition, Boltzmann equation solver is used to compensate the effect of the electron energy distribution function (EEDF) shape in the global model, and the general expression of energy balance for non-Maxwellian electrons is developed. In the experiments, a number of traditional plasma diagnostic methods are used to compare with calculated results such as Langmuir probe, optical emission spectroscopy (OES), optical absorption spectroscopy (OAS) and two-photon absorption laser-induced fluorescence (TALIF). These theoretical and experimental methods are applied to understand several interesting phenomena in low pressure ICP discharges. The chemical and physical properties of low pressure ICP discharges are described and the applications of these methods are discussed.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.117-122
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• 2002

This study assesses the wear process of particle impingement erosion which is a major source of erosion among fluid power components. First, Bitter's theory was modified to simplify engineering calculations. Second, actual experiments were conducted to validate the modified equation. And the effect of concentration and size distribution of impinging particles was tested. Little deviation from the prediction of the modified equation was observed. To develop complete analytical approach to the erosion mechanism, further experimental data are required to establish a correlation with other engineering parameters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2364-2367
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• 1999

Polymer insulating materials are widely used in power distribution and transmission systems for their good dielectric properties, light weight, low cost, and good contamination performance. Tracking is one of the biggest problems to be overcome in polymer insulating materials. The alumina trihydrate(ATH) is widely used as a filler for improve the tracking performance of silicone rubber. In this paper, we have investigated the influence of surface treatment of fillers on the tracking performance of silicone insulator using the IEC 587 tracking test method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.10-14
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• 2001

In order to assess the long-tenn reliability of polymer insulators for distribution power systems, we have developed the accelerated aging test method which can simulate the operation conditions. In this study, 3000 hours aging test for 4 kinds of polymer insulators has been completed by the developed accelerated aging test. After 3000 hours aging test, visual inspection and electrical tests were carried for identifying a change of characteristics. Some specimens showed the surface erosion and the manufacturing defect. In the electrical tests, the wet flashover voltage was significant1y decreased by the accelerated aging test. In comparison with the field-aged polymer insulators, it can be concluded that the developed test method can evaluate the long-tenn reliability within short time and screen the manufacturing defect.

• Coupled systems mechanics
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• 제4권1호
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• pp.99-114
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• 2015

In this paper, a refined exponential shear deformation beam theory is developed for bending analysis of functionally graded beams. The theory account for parabolic variation of transverse shear strain through the depth of the beam and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. Contrary to the others refined theories elaborated, where the stretching effect is neglected, in the current investigation this so-called "stretching effect" is taken into consideration. The material properties of the functionally graded beam are assumed to vary according to power law distribution of the volume fraction of the constituents. Based on the present shear deformation beam theory, the equations of motion are derived from Hamilton's principle. Analytical solutions for static are obtained. Numerical examples are presented to verify the accuracy of the present theory.

• Nuclear Engineering and Technology
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• 제15권1호
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• pp.41-49
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• 1983

특정 원자력발전소 안전성 계통의 신뢰도 분석을 위한 자료평가의 목적으로 전산코드를 개발하였으며 그 유용성을 입증하였다. 가압 경수로 보조급수 계통 신뢰도 분석을 위하여 개발된 전산코드를 이용하여 관련자료를 평가하였다. 이를 위하여 부품고장률의 선분포는 미국의 원자력안전성 연구보고서, 특정 발전소의 운전경험은 기 발간된 인허가자 사상보고서에서 얻었다. 분석결과 후분포는 대수정규분포 곡선에 잘 점철되며 분포의 오차인자들은 현저히 감소하는 것으로 나타났다.

• Nuclear Engineering and Technology
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• 제48권4호
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• pp.975-981
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• 2016

The containment response during the first 24 hours of a low-pressure severe accident scenario in a nuclear power plant with a two-loop Westinghouse-type pressurized water reactor was simulated with the CONTAIN 2.0 computer code. The accident considered in this study is a large-break loss-of-coolant accident, which is not successfully mitigated by the action of safety systems. The analysis includes pressure and temperature responses, as well as investigation into the influence of spray on the retention of fission products and the prevention of hydrogen combustion in the containment.

• 드라이브 ㆍ 컨트롤
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• 제12권1호
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• pp.21-27
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• 2015

Pneumatic cylinders are classified into rod-type pneumatic cylinders and rodless pneumatic cylinders depending on the presence of the rod. Rodless cylinders have a constant area and have no deflection. Rodless cylinders are widely used in automatic systems requiring high-speed performance and high-precision transportation. However, the research of the pneumatic cylinder has been focused on the structure and life characteristics. In this research, aging characteristics and shape parameter analysis which are related to the lifetime were investigated. By conducting the lifetime tests with two different materials for the transfer plate, the failure mode and lifetime characteristics were analyzed. By the Anderson-Darling (A-D) verification based on the complete data set, the analysis results of lifetime distribution, shape parameter, and scale parameter were provided.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.350-351
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• 2013

본 논문은 가정용 DC 배전 시스템을 위한 DAB 컨버터 구조의 양방향 절연형 밧데리 충전기를 제안한다. 가정용 DC 배전 시스템은 양방향 AC-DC 정류기, 신재생 에너지원, 에너지 저장 시스템, 가정용 가전기기, 조명 등으로 구성되어진다. 가정용 DC 배전 시스템의 안정적인 동작을 보장하고 부하에 안정적인 전력을 공급하기 위하여 에너지 저장 시스템은 가정용 DC 배전 시스템에 필수적으로 요구되어진다. 다양한 양방향 DC-DC 컨버터 중에서, DAB 컨버터는 고주파 변압기로 절연된 고효율의 승압/강압이 가능한 양방향 DC-DC 컨버터이다. 본 논문에서는 DAB 컨버터의 기본적인 동작 특성과 설계 원리를 설명하고 가정용 DC 배전 시스템을 위한 밧데리의 충/방전 알고리즘을 제안한다. 제안한 밧데리 충전기의 성능을 검증하기 위하여 3kW(380Vdc 입력, 150-200Vdc 출력) DAB 컨버터를 제작/테스트하였다.