• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.142-150
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• 1997

A numerical analysis is carried out to study the effect of piston shape on the lubricaton characteristics between the cylinder and piston in hydraulic piston pump. The shapes of piston affect significantly the pressure distributions, the lateral force and leakage flowrate. Composite shaped piston is more effective than other shapes which not only reduces the possibility of hydraulic locking but improves the volumetric efficiency of the piston pump.

• The KSFM Journal of Fluid Machinery
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• v.3 no.3 s.8
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• pp.25-30
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• 2000

Thermodynamic method of pump performance measurement calculates pump efficiency and flowrate by measuring fluid temperature increase and pressure rise through the pump. The theory of this method is investigated and precise comparison experiment with classical hydraulic method was conducted to verify the accuracy. Classical hydraulic pump performance measurement results and Yatesmeter results based on the thermodynamic method showed good agreement in measured performance.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.105-110
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• 2003

The hydraulic excavator has been a popular research object for automation because of its multi-workings and economic efficiency. When it works crane tasks, most of disasters happen. The objective of this paper is to design each components and to construct boom, arm, bucket circuit. These models modeled with AMESim show us change of variables and behavior of excavator. Simulation model will be used for simulator of excavator.

• Proceedings of the KWS Conference
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• 1996.05a
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• pp.34-37
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• 1996

The expanding method of tube to tubesheet joint part on neclear steam generators are classified into three classes of roller expanding, explosive expanding and hydraulic expanding. After the expanded Mock-Up specimen are made by the three expanding method. The general properties, microstructure/microvickers hardness, pull-out strength, hydraulic leak pressure, of tube to tubesheet joint part were inspected. and We evaluated the operation efficiency of expansion, reproduction of expanded joint about three expanding method. Through the overall evaluation of tube to tubesheet joint part, The hydraukic expanding and explosive expanding could be certificated more useful expanding method.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.3
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• pp.314-321
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• 2020

In this work, a preliminary design of an inlet guide vane and runner for developing a 2.5 kW hydraulic turbine was conducted by using computational fluid dynamic analysis. Three-dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model were used to analyze the fluid flow in the hydraulic turbine. The hexahedral grid system was used to construct computational domain, and the grid dependency test was performed to obtain the optimal grid system. Velocity triangle diagram considering the flow angles of the inlet guide vane and runner was analyzed to obtain a basic geometry of the inlet guide vane and runner. Through modification of the preliminary design, the hydraulic performances of the turbine have improved under overall drop conditions. Especially, the efficiency and power of the turbine increased by 0.95% and 1.45%, respectively, compared to those of the reference model.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.701-704
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• 2005

Aquifer Thermal Energy Storage (ATES) can be a cost-effective and renewable geothermal energy source, depending on site-specific and thermohydraulic conditions. To design an effective ATES system having influenced by groundwater movement, understanding of thermo hydraulic processes is necessary. The heat transfer phenomena for an aquifer heat storage are simulated using FEFLOW with the scenario of heat pump operation with pumping and waste water reinjection in a two layered confined aquifer model. Temperature distribution of the aquifer model is generated, and hydraulic heads and temperature variations are monitored at the both wells during 365 days. The average groundwater velocities are determined with two hydraulic gradient sets according to boundary conditions, and the effect of groundwater flow are shown at the generated thermal distributions of three different depth slices. The generated temperature contour lines at the hydraulic gradient of 0.00 1 are shaped circular, and the center is moved less than 5m to the groundwater flow direction in 365 days simulation period. However at the hydraulic gradient of 0.01, the contour center of the temperature are moved to the end of boundary at each slice and the largest movement is at bottom slice. By the analysis of thermal interference data between two wells the efficiency of the heat pump system model is validated, and the variation of heads is monitored at injection, pumping and no operation mode.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.263-267
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• 2007

Even though Waterpower Generation as pollution-free has its own merit of contribution by supply of good quality electricity, due to the noise made at the time of its operation, a normal mutual communication among the workers and technicians engaging at the hydraulic turbine dynamo room is almost impossible, and since those finishing materials had been used mainly by reflection material, it is actual situation that when working for maintenance in the hydraulic turbine dynamo room, as counterpart's voice vibrates, its working efficiency is difficult to ensure. On such view point, this Research has conducted Psycho-acoustics Experiment about voice Definition using Auralizational Technique, on the object for the hydraulic turbine dynamo room that improved its acoustic performance by computer simulation. As the result of Study, it was known that the clearness of sound with regard to voice information transmission was apparently improved in all items than before improvement. Therefore, it is considering that these results would be utilized usefully when renovation on the hydraulic turbine dynamo room in the future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.2
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• pp.85-90
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• 2004

The effect of the hydraulic residence time (HRT) for the removal of aquarium waste, such as protein, total suspended solids (TSS) and turbidity were investigated by using a foam separator Protein, TSS and turbidity removal efficiencies were increased with the increase of hydraulic residence time. The optimum hydraulic residence time was 0.5 min, and the highest protein and TSS removal rates were $14.4\;g/L{\cdot}day\;and\;38.9\;g/L{\cdot}day,$ respectively. The tendency of turbidity removal rate and efficiency was similar to that of protein.

• Journal of Mechanical Science and Technology
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• v.20 no.3
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• pp.358-365
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• 2006

The hydraulic pump of an Electro-hydrostatic Actuator should be able to quickly feed large volume of oil into hydraulic cylinder in order to reduce the response time. On the other hand, it should be also able to precisely dispense small amount of oil through low-speed operation so that the steady state position control error of the actuator can be accurately compensated. Within the scope of axial piston type hydraulic pumps, this paper is focused on the investigation how the surface treatment of their cylinder barrel with TiN plasma coating can contribute to the reduction of the friction and wear rate of valve plate in the low-speed range with mixed lubrication. The results showed that the friction torque of the valve plate mated with a TiN coated cylinder barrel could be reduced to 22% of that with an uncoated original one when load pressure was 300 bar and rotational speed 100 rpm. It means that the torque efficiency of the test pump was expected to increase more than 1.3% under the same working condition. At the same time, the wear rate of the valve plate could be reduced to $40\sim50%$.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.5
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• pp.169-175
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• 2013

CRDi technology of diesel engine was developed from in the early 2000s due to a need to increase fuel efficiency and environment care. Especially, high-pressure fuel injection system in CRDi system which has a fuel injection unit including an injector, a fuel pump and common-rail, etc. becomes possible to make the exhaust gas clean as well as power improvement. In this study, comparison of dynamic characteristics of servo-hydraulic piezo-driven injector with 3-way and bypass-circuit type was analyzed by using the AMESim code. As results of this study, it found the bypass-circuit inside servo-hydraulic piezo injector can cause a faster injection response than that of the 3-way type. Also it was shown that bypass-circuit type had better control capability due to hydraulic bypass system.