• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.828_829
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• 2009

본 논문에서는 가변속 펌프 시스템에 적합한 SRM의 최적 구동을 위한 예측 방법에 대해 나타내었다. 회전자의 위치에 따른 쇄교 자속 곡선 모델링을 통하여 제안된 방법에 의해 전류의 최적 인가 시점을 테이블로 구성하였으며, 이를 기반으로 SRM 제어기 및 알고리즘을 Matlab/Simulink를 이용하여 시뮬레이션을 통해 결과값을 나타내었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.355-358
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• 2003

This paper presents characteristics of vacuum preloaded porous air bearing. Pressure distribution of a porous pad and vacuum pocket are calculated. And load capacity and stiffness of the bearing are analyzed with various vacuum parameters, that is. clearance height. tube diameter, tube length. pumping speed of vacuum pump, vacuum pocket to porous pad area ratio. From the simulation results, optimum clearance for best performance can be selected adjusting these parameters, especially tube diameter which is the most dominant source.

• 대한전자공학회논문지SD
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• 제45권4호
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• pp.137-145
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• 2008

본 논문에서는 출력 단 전달 스위치로 NMOS와 PMOS를 병렬 결합하여 사용하고 벌크 펌핑 회로를 채용한 CMOS 전하펌프를 제안하였다. 제안된 전하 펌프는 NMOS 및 PMOS의 병렬 결합을 통하여 출력 단의 전류전달 능력을 향상시킬 수 있다. 또한, 채용된 벌크 펌핑 회로는 PMOS에 의한 벌크의 순방향 바이어스 문제를 효과적으로 해결할 수 있다. 제안된 회로의 성능을 확인하기 위하여, 80-nm CMOS 공정기술을 이용하여 전하 펌프를 설계하였다. 모사실험을 통한 비교 결과, 제안된 CMOS 전하 펌프는 기존의 NMOS 혹은 PMOS 만을 사용한 전하 펌프들과 비교하여 47% 이상의 전류전달 능력의 향상을 가져왔고 펌핑 속도도 9% 이상 개선되었으며, 동작 시 최대 벌크 순방향 전압 또한 24%이상 개선되어 벌크 순방향 바이어스 문제가 완화되었음을 확인하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.73-76
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• 2009

Generally, wind or solar power system is operated as a stand-alone power system, the efficiency of which could be higher by designing wind-solar combined system considering average wind speed and solar radiation of the desert region, Mongolia. This system is designed to generate electricity for power users and pumps the ground water for irrigation using deep well pump. The ground water can be used for farming or forestation where there is no or little irrigation system. In connection with this study, a renewable energy park, Green Eco Energy Park, was developed at about 50km east of Ulaanbaatar. 3 sets of 10kW wind power generator and 70 kW of solar power module were installed there. The electricity generated from the system is used to on-site office building and deep well pump for ground water pumping. A 10kW stand-alone solar pumping system, which has no rechargeable battery system, is installed to pump the ground water with the amount of generated power. The ground water is stored in 3 artificial ponds and then it is used for raising nursery tree and farming. The purpose of this study is to provide a possible energy solution to desert regions where there is no or little power system. The system also supply power to ground water pump, and the water can be used for farming and forestation, which will also be a solution of preventing desertification or spreading of desert area.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.159-164
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• 2001

An extensive range of pumping facilities are employed in the regional water supply system in metropolitan areas, and optimization and the systematic combination of the pump facilities have direct bearing on the stability and economy of the water supply system concerned. These systems must be able to guarantee stability, efficiency and offer high reliability. Preparation of metropolitan area regional water supply system construction project must include a basic plan which takes into account the suitability of pumping facilities to be used, the environment in which facilities will be installed, man-power requirements and basic operational and management policies. This paper contains over-all analysis of the management of metropolitan area regional water supply systems and highlights the cause of Inefficiency and energy waste and puts forward a remedial plan of action. In addition, pump/motor specification programs were developed using Visual Basic to assist selection of the same.

• 한국진공학회지
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• 제7권1호
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• pp.1-4
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• 1998

이온 펌프의 중심에 네그(Non-Evaporable Getters)가 삽입된 새로운 조합 펌프를 사용하여 극고진공 시스템을 구현하였다. 진공 용기는 터보 분자 펌프만으로도 극고진공에 성공하였던, $450^{\circ}C$에서 잘 산화된 304 스테인레스 스틸 쳄버를 사용하였다. 시스템의 압력은 Leybold사의 EXG(Extractor Gauge)로 측정하였으나, 본 실험에서의 최고 진공도는 이미 그 게이지의 측정 한계인 1~$2\times10^{-12}$torr범위를 훨씬 지나 게이지 지시가 $-0\times10^{-12}$torr를 읽교 있는 극고진공에 도달해 있었다. 이는 효과적인 네그 활성화로 수소 가스에 대한 배기 속도 를 크게 향상시켜준 결과라 볼 수 있다. 또한 본 실험은 극고진공 표면 분석 장치의 실현 가능성을 시사해주는 것으로, 앞으로의 초미세 표면 과학에 있어서 새로운 장을 열어줄 것 으로 기대된다.

• 한국진공학회지
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• 제18권4호
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• pp.272-280
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• 2009

원판형 분자 드래그펌프 내부의 회전자 위치에 따른 압축 성능과 배기특성에 대하여 실험과 수치 해석적으로 고찰하였다. 실험은 각각의 회전자 위치에 진공압력 게이지들을 부착하여, 펌프의 출구 압력이 0.2 Pa에서 533 Pa 사이일 때, 각 회전자에서의 압력을 측정하였다. 압력측정범위는 출구 압력이 0.2 Pa에서 533 Pa 범위사이에서 측정하였다. 진공펌프 로터의 회전 속도는 24,000 rpm이며, 질소 가스를 사용하여 성능실험을 수행하였다. 본 연구에서는 원판의 단의 수에 따른 원판형 분자 드래그펌프의 성능특성을 파악하고자 하였다. 수치해석을 통해 내부 유동채널에 대한 구체적인 압력 분포를 파악하였으며, 수치해석의 신뢰도 파악을 위하여 실험 측정값과 수치해석 값을 비교하여 검증하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1222-1229
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• 2011

Railway bridges are divided into ballastless and ballast track bridges. The ballast abrasion occurs on the ballast track upon bridges more than soil roadbed because the track vibration occurs a lot in the ballast track upon bridges due to girder vibration when a train's weight is loaded onto track even though the identical ballast is used. The phenomena of mud pumping especially, which occurs when drainage is not properly secured for heavy rain, leads to the increase of maintenance work load and the decline of ride comfort. There are countermeasures such as ballast change, installation of cross-drainage for poor drainage, gutter establishment, ballast lifting methods, ballast mats and resilient sleepers laying for the mud pumping. The ballast thickness range in domestic railroad construction rule is uniformly set up according to the design speed of railroad and passing tonnage of train without considering field conditions which is considered in foreign railroad companies. The purpose of this study is to verify the effect of vibration decrease by measuring the acceleration, displacement and ride comfort of ballast track with the change of ballast thickness on the ballast track bridges and to suggest the optimal height of ballast on the Yocheon Bridge built for the test in Honam Line.

• 대한기계학회논문집
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• 제18권12호
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• pp.3386-3394
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• 1994

An experimental study has been performed on the flow over a rotating disk, where the diameter of the disk is 500 mm and the maximum vertical deviation of the upper surface is $50 \mu{m}$ for the whole range of the angular velocity up to 3400 rpm. The flow visualization experiment for the wall jet flow induced by impinging circular jet is carried out using schlieren system and measurements are made by 3-hole and 5-hole pitot tubes. Schlieren photographs show that as the rotating speed increases the wall jet flow becomes more stable and the size of the largest eddies becomes smaller. Measurements for impinging jet flow on the stationary disk verify the accuracy of the present experiment, and those for free rotating disk flow display the existence of transition region from laminar to turbulent flows. Measurements for impinging jet flow on the rotating disk exhibit the interaction between the wall jet and the viscous pumping effect, which explains the decay in size of turbulent eddies illustrated by the schlieren photographs.

• 설비공학논문집
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• 제8권2호
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• pp.219-229
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• 1996

In the free molecular flow range, the pumping performance of a turbomolecular pump has been predicted by calculation of the transmission probability employing the integral method and the test particle Monte-Carlo method. The velocities of molecules incident upon a moving blade are given by the random numbers, which are sampled from the Maxwell molecular velocity distribution function. The present results agree quantitatively with the previous known numerical results. For a multi-stage pump, the velocity profile of molecules between two blade rows is not Maxwell distribution. In this case, the Monte-Carlo method is employed to calculate the overall transmission probability for the entire set of blade rows. When the results of the approximate method combining the single stage solutions are compared with those of the Monte-Carlo method for the pump having six rows at C=0.6, the approximate method overestimates as much as 36% in the maximum compression ratio and 19% in the maximum pumping speed than does the Mote-Carlo method.