• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.186-193
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• 2001

In the high pressure state, the leakage flow rate of hydraulics is one of serious problems and the great reason to decrease the volume efficiency. In this paper, I tried to clarify tribology characteristics for the slipper hydrostatic bearing in swash plate type axial piston pumps and motors by means of experiment . I measured the leakage flow rate between swash plate and piston shoe with change the supply pressure and oil temperature at a swash plate angle of 0。 . And I also investigated the slipper pocket pressure and calculated oil film thickness for theoretical method. So. 1 have analyzed the tribology characteristics of hydrostatic bearing for leakage flow rate and oil film thickness with oil temperature and supply pressure.

• 한국유체기계학회 논문집
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• 제3권4호
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• pp.52-58
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• 2000

The numerical study on the waterhammer was carried out for the intake pumping station of the metropolitan water supply 6th stage project. Because the waterhammer problems as a result of the pump power failure were the most important, these situations were carefully investigated. The surge tank and the stand pipes effectively protected the tunnels md the downstream region of pipeline from the pressure surge. In case the moment of inertia of the pump and motor was above $5080\;kg{\cdot}m^2$, the column separation did not occur in the pipeline between the pumping station and the inlet of 1st tunnel. As the moment of inertia increased, the pressure surges decreased in the pipeline conveying raw water. The pump control valve was chosen as the main surge suppression device for the intake pumping station. After power failure, the valve disc should be rapidly closed in 2.5 seconds and controlled the final closure to 15 seconds by the oil dashpot. If the slamming happened to the pump control valve, there was some danger of this system damaging. As the reverse flow through the valve increased, the upsurge extremely increased.

• 한국유체기계학회 논문집
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• 제8권4호
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• pp.20-26
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• 2005

When the pumps are started or stopped for the operation or tripped due to the power failure, the hydraulic transients occur as a result of the sudden change in velocity. The field tests on the waterhammer were carried out for Pangyo booster pumping station in which had six booster pumps and two in-line pumps with the motor of output 1,700 kW, respectively. The booster pumping station was equipped with the pump control valve as the main surge suppression device, and the surge relief valve as auxiliary one. But the pump control valve had not early controlled in the planned closing mode, the slamming occurred to the valve of which abruptly closed during the large reverse flow. Because the positive pressure wave caused by the pump failure was superposed on the slam surge, the upsurge increased so extremely that the pump control valve was damaged. After the air chambers were additionally installed in the booster pumping station, it was preyed that the water supply system acquire the safety and reliability on the pressure surge.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.576-579
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• 2008

The purpose of study is a development of the high reliance electric driven water-pump that fuction is forcing the movement of water using basic design, proto sample and test at the cooling system. It was important to supply a coolant quickly and accurately for the requirement of flow rate at the system when we carried out the designs for BLDC Moter, Controller and water pump(Impeller, Volute Casing, Sealing Device) First, we attained ours purpose that the target efficiency for water pump was over 40% and then we are doing the optimum design for Brushless Motor and Controller that its target is over 55% of efficiency.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.217-220
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• 2007

The purpose of study is a development of the high reliance electric driven water-pump that fuction is forcing the movement of water using basic design, proto sample and test at the cooling system. It was important to supply a coolant quickly and accurately for the requirement of flow rate at the system when we carried out the designs for BLDC Motor, Controller and water pump(Impeller, Volute Casing, Sealing Device) First, we attained ours purpose that the target efficiency for water pump was over 40% and then we are doing the optimum design for Brushless Motor and Controller that its target is over 55% of efficiency.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.172.1-172.1
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• 2010

In Jeju, underground air is used for heating greenhouse and fertilizing natural $CO_2$ gas by suppling directly into greenhouse. But greenhouse heating method by direct supply of underground air has several problems as like low temperature below $20^{\circ}C$ or high relative humidity over 90%. The underground air is inadequate in heating of crops such as mangos, oranges with the growing temperature over $20^{\circ}C$. Also if the relative humidity of greenhouse is kept with over 90%, diseases can strike almost of the crops. And also the ventilation loss becomes larger because the air pressure of inside greenhouse by direct supply of underground air is higher. In this study the heat pump system using underground air as heat source was developed and heating performance of the system was analyzed. Heating COP of the system was 2.5~5.0 and rejecting heat into greenhouse and extracting heat from underground air in this heat pump system were 46.5~31.4 kW, 34.9~20.9 kW respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.110-115
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• 2014

The nuclear power plant was launched by Kori unit 1 in 1978 years. Currently, 23 nuclear power plants have been operating in Korea since 1978 years. The localization was completed for most of the reactor facility from Hanbit(Youngkwang) unit 3&4. However, RCP(Reactor Coolant Pump) and MMIS(Man Machine Interface System) is an important technology that has been excluded from the scope of the technical transfer has been dependent on a specific overseas vendor. Recent success in RCP development through co-operation with government and industries. Developed RCP will be applied to Shin-Hanul unit 1&2 nuclear power plants. The RCP operates in high speed and high pressure condition and only rotating component in the NSSS(Nuclear Steam Supply System). Therefore, the problem of vibration has arisen caused by the hydraulic forces of the working fluid. These forces can influence on the stability characteristics for entire RCS(Reactor Coolant System) loop, and can act as significant destabilizing forces. In this study, vibration evaluation of the pump shaft of development RCP estimated under normal operation and over speed conditions. In order to predict the vibration characteristics and dynamic behavior, modal analysis, critical speed analysis and unbalance response spectrum analysis were performed.

• 설비공학논문집
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• 제29권1호
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• pp.38-42
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• 2017

This study proposes an idea for energy saving in apartment machine rooms. A conventional district heating system is equipped with constant-flow pumps and bypass valves to regulate pump differential pressure. Each family unit is equipped with a constant-flow on/off valve. This leads to excessive hot water circulation and a high return temperature. To reduce energy loss, this study assumes that each family unit is renovated with a heating valve which regulates the return temperature at $35^{\circ}C$. The hot water supply pump is also replaced with a pump with an inverter to vary flow rate. Expected energy savings is then estimated from field test data. According to the results, pump electricity consumption was reduced by 6,100 kWh for a family unit building over about half a year. The supply temperature can also be lowered by $5^{\circ}C$, which can contribute to a production of electricity of 10.3 kWh/ton of hot water.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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• pp.45-49
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• 2001

To maintain the freshness of produce, because of stand away between produced and consumer, we need refrigeration system that can supply to consumer at cold chain as soon as gathering. General refrigeration system consist of refrigeration chamber or low temperature store. But the vacuum technology can rapidly refrigeration without refrigerator. This precool system possible to get low precooled temperature, suitable for the fishes, the meat, the vegetables, the fruit etc. Especially get advantage that quality maintain through rapid refrigeration of ferment directly generate heat. Vacuum precool system's principle is that water saturated temperature reduce according to pressure is get to vacuum area, so product temperature reduce as water evaporation at product. In vacuum suction, unit, on early experiment period run the rotary type vacuum pump at purpose pressure, then maintain pressure by water-diven ejector. As the results, cabbage took about 60 minutes to reach from $23.2^{\circ}C$ to $4.5^{\circ}C$at 5mgHg abs.

• 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.