• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 추계학술대회 논문집
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• pp.295-299
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• 2007

This paper presents the photovoltaic(PV) water pumping system with a maximum power point tracking(MPPT). The wale- pumping system uses a variable speed single phase induction motor(SPIM) driven a centrifugal pimp by field oriented control(FOC) inverter. The MPPT using a DC-DC converter controlled the duty cycle to track maximum power from PV under different insolation conditions. The duty cycle directly relate with a flux producing current control($i_{ds}$). The FOC inverter uses a current control voltage source inverter(CC-VSI). The simulation results are shown that the characteristics and performance of drive system, which varies as each conditions of light by expresses in voltage ($V_{dq}$), current($I_{dq}$), speed of motor and torque.

• 한국진공학회지
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• 제8권3B호
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• pp.257-261
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• 1999

The claw pump, one of oil-less dry pumps developed to solve problems found in vacuum systems pumped by oil-sealed rotary pumps, has been widely used separately or as a part of compound structure with a roots pump. The claw pump has some merits such as a high pumping speed, a high compression ratio, and relatively little heat generation. The high compression ratio of the claw pump is compression ratio, and relatively little heat generation. The high compression ratio of the claw pump is based on efficient sweeping action of the special type rotor and an intrinsic self-valving mechanism. The contour of the rotor with claw-type blade is designed basically to make two rotors revolve smoothly without touching with each other, and related dimensions are determined by required pumping speed, compression ratio, power demand and diameter of the rotor axis. In this paper the procedure of designing the rotor of the claw pump is described and factors influencing the pump performance are analyzed.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권1호
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• pp.1-8
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• 2018

As the key equipment in deep ocean mining, the slurry pump suffers from wear and blocking problems. In this paper, high-speed photography technique is applied to track the movement rule of single particle of the coarse particle solid-liquid two-phase flow in a double blade slurry pump. The influences of particle diameter and particle density on the pass-through and collision characteristics of particles are analyzed as well. The results show that the average of the passing pump time first decreases and then increases when the particle diameter increases. The average of the passing pump time decreases by 22.7%, when the particle density increases from $1.09g/cm^3$ to $1.75g/cm^3$. Besides, the particle density has great influence on the location where the particle hits the tongue. Most particles of $1.09g/cm^3$ hit the tongue on the left side, while collision location of particles of $1.75g/cm^3$ is mainly on the top and at the right side of the tongue. The research can provide a basis for the optimization design of slurry pump in deep ocean mining system.

• 한국유체기계학회 논문집
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• 제6권3호
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• pp.58-63
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• 2003

The performance of turbo pump drops rapidly and it gets into break-down when the void fraction reaches above the threshold value because the impeller flow passage is choked up with air bubbles. Phenomenological understanding of break-down and pumping recovery mechanisms under air-water two-phase flow conditions are therefore important for pump designers and essential assignment for researchers. In this paper, we investigated the characteristics of break-down and pumping recovery due to entrained air occurring inside a screw-type centrifugal pump which has a wide flow passage mainly through the findings of suction and discharge pressures, rotational speed, flow rate measurements and visualization.

• International journal of advanced smart convergence
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• 제5권2호
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• pp.1-7
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• 2016

Recently, with the development of advanced thin film devices comes the need for constant high quality vacuum as the deposition pressure is more demanding. It is for this reason our research seeks to understand how the variable design factors are employed in such vacuum systems. In this study, the effects of design factor applications on the vacuum characteristics were simulated to obtain the optimum design modeling of variable models on an ultra high vacuum system. The commercial vacuum system simulator, $VacSim^{(multi)}$, was used in our investigation. The reliability of the employed simulator was verified by the simulation of the commercially available models of ultra high vacuum system. Simulated vacuum characteristics of the proposed modeling aligned with the observed experimental behavior of real systems. Simulated behaviors showed the optimum design models for the ideal conditions to achieve optimal pressure, pumping speed, and compression ratio in these systems.

• 한국정밀공학회지
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• 제16권5호통권98호
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• pp.74-82
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• 1999

To meet the needs of the hydraulic excavator of large capacity, tandem axial type piston pump which is high pressure and high speed have been developed. But inevitably we can not help facing the problem of noise at that time. In order to reduce the noise of this pump, many researchers have been studying the problem of oil distribution manner. But they are not interested in the symmetric structure of tandem type pump. So, focusing on the symmetric structure of tandem type pump, this paper analyzed unbalanced force developed in the pump chamber and verified the effect of the pumping phase of the piston on vibration and noise of the tandem axial type piston pump theoretically.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2723-2728
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• 2008

The present study is numerically and experimentally performed to reveal the pumping characteristics of a helical-type molecular drag pump (HTDP) in the molecular transition flow region. In the experimental study, the pressures are measured simultaneously at the 5 positions along the helical channel of rotor under various conditions of outlet pressure and throughputs, and nitrogen is used as test gas. The outlet pressure is in the range of 26-533 Pa. As results, the local pressure changes are checked corresponding to the various outlet pressure and throughput of HTDP. In the numerical study, Navier-Stokes equations with slip boundary conditions are employed (Re< 1000, Kn< 0.1). The local pressure distribution and the pumping speed are calculated. The numerical results are compared with the experimental results. The numerically computed value agrees with the experimental data within an error of approximately 5%.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2159-2164
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• 2002

This paper reports on the effects of additional factors on the engine friction characteristics. The total friction loss of engine is composed of pumping and mechanical friction loss. The pumping loss was calculated from the cylinder pressure, and the mechanical friction loss was measured by strip-down method under the motoring condition. The various parameters were tested. The engine friction loss was much affected by oil and coolant temperature. The low viscosity oil was very effective to reduce the friction loss, and friction modifier was very useful to reduce the friction loss at lower engine speed. The engine friction loss was varied with engine running time because of surface roughness decreasing and oil degradation. To prevent oil-churning effect, it was very important to maintain the proper oil level. The presented results will be very useful to understand friction characteristics of engine.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1993년도 제4회 학술발표회 논문개요집
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• pp.124-125
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• 1993

• 대한전자공학회논문지SD
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• 제45권7호
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• pp.37-43
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• 2008

본 논문에서는 전하 펌프 방법 (Charge Pumping Method, CPM)를 이용하여 서로 다른 질화막 층을 가지는 N-Channel SANOS (Silicon-$Al_2O_3$-Nitride-Oxide-Silicon) Flash Memory Cell 트랜지스터의 트랩 특성을 규명하였다. SANOS Flash Memory에서 계면 및 질화막 트랩의 중요성은 널리 알려져 있지만 소자에 직접 적용 가능하면서 정화하고 용이한 트랩 분석 방법은 미흡하다고 할 수 있다. 기존에 알려진 분석 방법 중 전하 펌프 방법은 측정 및 분석이 간단하면서 트랜지스터에 직접 적용이 가능하여 MOSFET에 널리 사용되어왔으며 최근에는 MONOS/SONOS 구조에도 적용되고 있지만 아직까지는 Silicon 기판과 tunneling oxide와의 계면에 존재하는 트랩 및 tunneling oxide가 얇은 구조에서의 질화막 벌크 트랩 추출 결과만이 보고되어 있다. 이에 본 연구에서는 Trapping Layer (질화막)가 다른 SONOS 트랜지스터에 전하 펌프 방법을 적용하여 Si 기판/Tunneling Oxide 계면 트랩 및 질화막 트랩을 분리하여 평가하였으며 추출된 결과의 정확성 및 유용성을 확인하고자 트랜지스터의 전기적 특성 및 메모리 특성과의 상관 관계를 분석하고 Simulation을 통해 확인하였다. 분석 결과 계면 트랩의 경우 트랩 밀도가 높고 trap의 capture cross section이 큰 소자의 경우 전자이동도, subthreshold slop, leakage current 등의 트랜지스터의 일반적인 특성 열화가 나타났다. 계면 트랩은 특히 Memory 특성 중 Program/Erase (P/E) speed에 영향을 미치는 것으로 나타났는데 이는 계면결함이 많은 소자의 경우 같은 P/E 조건에서 더 많은 전하가 계면결함에 포획됨으로써 trapping layer로의 carrier 이동이 억제되기 때문으로 판단되며 simulation을 통해서도 동일한 결과를 확인하였다. 하지만 data retention의 경우 계면 트랩보다 charge trapping layer인 질화막 트랩 특성에 의해 더 크게 영향을 받는 것으로 나타났다. 이는 P/E cycling 횟수에 따른 data retention 특성 열화 측정 결과에서도 일관되게 확인할 수 있었다.