• 설비공학논문집
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• 제8권2호
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• pp.187-197
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• 1996

A computer program for thermal design analysis has been developed to predict the operating characteristics and performance of an absorption heat pump to recover $30{\sim}40^{\circ}C$ of waste hot water. The effects of heat transfer area of the system components, temperature and mass flow rate of heat transfer medium, and solution circulation rate on the system performance are investigated in detail. The results obtained indicate that the COP is increased with a decrease in the temperature of driving steam and with an increase in the temperature of waste hot water while the COP is little affected by the variation of a hot water temperature. It is also found that the heating output is increased with an increase in the temperature of waste hot water and driving steam as well as with a decrease in the temperature of hot water. The simulation results are also compared with the experimental results for a periodic operation of the system and obtained a satisfactory agreement.

• 한국산학기술학회논문지
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• 제14권5호
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• pp.2069-2074
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• 2013

내연기관 차량에 전자기식 클러치 워터펌프의 적용은 연비 향상 및 배기가스 저감을 꾀할 수 있다. 이러한 클러치 워터펌프는 엔진 냉각시스템의 유량 단속에 의하여 최적 운전 조건을 가능케 한다. 본 연구에서는 클러치 워터펌프를 이용한 냉각시스템을 제어함으로써 디젤 차량의 연비 및 배기가스 특성을 살펴보았다. 전자기식 클러치 워터펌프에 의한 저온 시동시 냉각수 흐름을 차단하여 아이들 조건에서 예열 시간을 기존 워터펌프 대비 49% 정도 단축시켰고, 주행 중에는 냉각수가 최적 고온상태를 유지하도록 제어하였다. 그리하여 NEDC 모드에서 연소 효율이 개선되어 최대 5% 정도의 연비 향상 효과를 나타내었다. 또한 NOx를 제외한 HC, CO 및 $CO_2$ 배기가스의 농도가 전반적으로 감소하였다.

• 한국산학기술학회논문지
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• 제14권10호
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• pp.4679-4684
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• 2013

기존 내연기관에 비해 전기자동차가 가지는 한계 중 하나는 에너지 밀도가 상대적으로 낮은 배터리로 인한 짧은 주행거리이며, 겨울철 실내 난방을 위하여 전기 히터 사용 시, 전기 소모량이 30%이상 증가하는 문제가 발생한다. 본 연구에서는 전기 히터보다 에너지 효율이 우수한 히트펌프를 이용하여 난방 시, 전기 자동차의 주행성능 변화를 조사하였다. 일차원 해석 프로그램인 AMESim Software를 이용하여 전기자동차의 구동시스템 및 히트펌프의 해석모델을 개발하였고, 해석 결과 전기 히터를 히트펌프로 대체하면, 배터리 소모량이 약 50% 감소하여 그 만큼의 주행거리를 증가시킬 수 있는 것으로 나타났다. 본 연구 결과는 전기자동차 난방을 위한 히트펌프의 장점을 입증하였으며, 향후 전기 자동차 난방 대책의 비전을 제시하는데 기여할 것으로 사료된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.3159-3162
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• 2008

A sensitivity analysis of the liquid rocket engine has been made. A mode analysis program is used to predict the performance change due to the variation of rocket engine operating environment. The propellant supply pressure and density are the major variables of the operating condition. The material properties of the turbine driving gas is assumed as the function of mixture ratio. The discrepancies of performance change between constant turbine driving gas properties and variable properties are greater for the case of fuel pump inlet pressure change than the oxidizer pump inlet pressure change.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.159-159
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• 2009

Existence of physical moving parts (ex. check valve) produces several problems (mechanical abrasion, deterioration of reliability, limited temperature performances etc.) in driving pumps. To overcome such problems, we proposed a valveless piezoelectric micro-pump which has new type volume transferring mechanism. The proposed micro-pump has a double faced disk type vibrator that can generate peristaltic motion formed by traveling wave in each surface of a disk. This type of micro-pump is able to apply to a fluid supply system that provides two different kinds of fluid simultaneously. In this paper, we propose a simple and novel design of piezoelectric micro-pump that is peristaltically by piezoelectric actuators and allows the removal of the need for valves of other physically moving parts. The finite elements analysis on the proposed pump model was carried out to verify its operation principle using the commercial analysis software.

• 대한전자공학회논문지SD
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• 제45권8호
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• pp.44-47
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• 2008

본 논문에서는 UWB PLL charge pump 의 충/방전 전류오차를 최소화하기 위한 회로를 제안하였다. Common-gate 와 Common-source 증폭기를 추가한 피드백 전압 조정기를 구성하여 높은 응답성을 가지는 charge pump를 설계하였다. 제안한 회로는 넓은 동작 영역을 갖으며, 낮은 전원 전압으로도 뛰어난 성능을 보인다. 본 회로는 1.2V 공급 전압과 IBM 0.13um CMOS 공정으로 집적되었다. 설계의 효율성을 평가하기 위해 참고 논문의 다른 회로와 성능을 대조하였다.

• 한국자기학회지
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• 제20권6호
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• pp.234-238
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• 2010

캠샤프트의 구동력을 활용한 기계식 연료펌프 시스템을 대체할 솔레노이드 격막 연료펌프는 최근 각광받고 있는 고효율 그린카 부품 중 하나이다. 하지만 솔레노이드 격막 연료펌프의 경우 왕복운동에 필요한 자속을 오직 솔레노이드에 의존하므로 전력소비가 비교적 큰 단점이 있다. 따라서 본 연구에서는 전력소모를 최소화 하기 위하여 영구자석형 VCA 연료펌프 시스템을 제안한다. 또한 상용전자기해석소프트웨어인 MAXWELL을 활용하여 유한요소 해석을 통해 기존의 솔레노이드 격막 펌프와의 전력소모 및 동적 성능을 비교 분석한다.

• 한국압력기기공학회 논문집
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• 제13권1호
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• pp.69-74
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• 2017

In the fire protection system or fire fighting water supply system, the jockey pump is generally installed for the prevention of the pressure decrease of pipes, the frequent driving of the fire pump and protection the pipes from the water hammer. In this paper, the pressure-rise in fire fighting water distribution pipes in condition of pipe pressurization by the surge tank at the start-up and the sudden-stop of the fire pump without additional installation of jockey pump is considered by using simple formula calculations and the evaluation of water hammer occurrence in condition of pipe pressurization by the surge tank is included. As a result, the pressure-rise of pipes is less than the pipe design pressure at the condition of pump's start-up and sudden stop, and the possibility of water hammer occurrence is remarkably low due to pressurization of the pipes by the surge tank.

• Journal of Mechanical Science and Technology
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• 제20권12호
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• pp.2079-2086
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• 2006

A fundamental study for developing a fault diagnosis system of a pump is performed by using neural network. Acoustic signals were obtained and converted to frequency domain for normal products and artificially deformed products. The neural network model used in this study was 3-layer type composed of input, hidden, and output layer. The normalized amplitudes at the multiples of real driving frequency were chosen as units of input layer. And the codes of pump malfunctions were selected as units of output layer. Various sets of teach signals made from original data by eliminating some random cases were used in the training. The average errors were approximately proportional to the number of untaught data. Neural network trained by acoustic signals can detect malfunction or diagnose fault of a given machine from the results.

• 한국정밀공학회지
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• 제33권2호
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• pp.95-100
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• 2016

Various processes have been developed to improve the performance of the lubrication oil pump in a recent automobile industry. In particular, trochoidal profile has been widely used for the lubrication oil pump because it is easy to flow control and a lot of oil feed rate is obtained. Accuracy of the trochoidal profile as a core component of the lubricating oil pump affects the driving performance. So, it is necessary to develop efficient processing of the trochoidal profile. In this study, a machining process for the trochoidal profile is developed by turn-mill. Cutting force, surface roughness and tool wear were evaluated in accordance with machining conditions.