• 대한기계학회논문집A
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• 제22권3호
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• pp.654-662
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• 1998

Shift quality of an automatic transmission in a vehicle is mainly affected by transient pressures in the hydraulic system during shifting. In this study, dynamic modelings of the hydraulic system and the power train of an automatic transmission are made systematically by a bond-graph method. The dynamic characteristics of the line pressures and clutch/brake pressures during shiftings are investigated by simulations and verified by experiments. The effects of clutch/brake pressures on the shift torque are also investigated through driving simulation.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(1)
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• pp.637-638
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• 2005

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.573-576
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• 1995

The realization by many industrial countries that manufacturing is a critical ingredient for attaining economic strength and stability has led to the development of automated systems which were proviously considered as gimmicks. The adaptive skill of the human operator is now being simulated and reproduced by computer that have become more powerful and less expensive. The work presented in this paper forms an investigation of the effects of dynamic viscosity and load of hydraulic oil an pressures with three different circuit(meter-in, meter-out and bleed off). The experimental results showed that pressures increase with an increase in dynamic viscosity and load in bleed off circuit, but there is no variation of pressure in meter-In meter-out circuit.

• Earthquakes and Structures
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• 제6권2호
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• pp.163-179
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• 2014

Dynamic test with scaled model of a group of intake towers was performed to study the dynamic interaction between water and towers. The test model consists of intake tower or towers, massless foundation near the towers and part of water to simulate the dynamic interaction of tower-water-foundation system. Models with a single tower and 4 towers were tested to find the different influences of the water on the tower dynamic properties, seismic responses as well as dynamic water-tower interaction. It is found that the water has little influence on the resonant frequency in the direction perpendicular to flow due to the normal force transfer role of the water in the contraction joints between towers. By the same effect of the water, maximum accelerations in the same direction on 4 towers tend to close to each other as the water level increased from low to normal level. Moreover, the acceleration responses of the single tower model are larger than the group of towers model in both directions in general. Within 30m from the surface of water, hydrodynamic pressures were quite close for a single tower and group of towers model at two water levels. For points deeper than 30m, the pressures increased about 40 to 55% for the group of towers model than the single tower model at both water levels. In respect to the pressures at different towers, two mid towers experienced higher than two side towers, the deeper, the larger the difference. And the inside hydrodynamic pressures are more dependent on ground motions than the outside.

• 한국농공학회지
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• 제38권5호
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• pp.85-94
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• 1996

For the geotechnical analysis in the construction and Deign of the coastal structures, one of the most important factors is the existence of waves. The dynamic behavior and deformation of the seabed subjected to wave load must be considered. It is expected that the soil behavior in the seabed subjected to cyclic wave load is much different from that on the ground subjected to dynamic forces such as earthquake. The purposes of this study are as follows ; Firstly, to provide a testing method to generate wave loads in the laboratory and measuring oscillatory pore water pressures in the unsaturated marine silty sand specimen, Secondly, to analyze the mechanism of wave induced pore water pressures and liquefaction potentials under the conditions in the testing. It is shown that the test set-up manufactured especially for the test is good to generate oscillatory wave pressures to the specimen with sine wave type. From the results of this study, it is understood that the pore water pressure due to induced waves is not accumulated as the wave number increases but is periodically varied with wave passage on still water surface. The magnitude of pore water pressures measured tends to be diminished radically with a certain time lag under the action of both high and low waves as depth increases.

• 대한기계학회논문집
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• 제16권2호
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• pp.191-199
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• 1992

This paper presents in experimental study of the dynamic internal pressure within an oil hydraulic vane pump. The measurements of the dynamic internal pressures near the vane of a pressure balance type of an oil hydraulic vane pump with intravanes has been made to provide the essential information for the study of the pump dynamics and control, the pump design and the analysis of tribological problems in the sliding components. The influences of the discharge pressure and rotating speed of the vane on the dynamic pressure in four chambers surrounding a vane have been investigated. The results indicate that the surge pressures of the chambers at the instant moment of discharge and closure are affected by the rotating speed. The pressure in the intravane chamber maintains almost constant values, which remarkably effects the pulsating discharge pressure.

• 대한기계학회논문집
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• 제18권5호
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• pp.1150-1157
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• 1994

This paper presents dynamic analysis of a hydraulic excavator based on experimental data. A three dimensional multibody model of a hydraulic excavator is modeled for the computer simulation. The hydraulic pressures acting on the cylinders are measured from experiments, and the forces exerting on the cylinders are calculated from the measured pressures. Using these forces, the dynamic analysis of the excavator is carried out to regenerate the motion in the computer simulation. A proper operation scheme is assumed to match the computational result and the experiment. The DADS program is used for the dynamic analysis.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.72-74
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• 1998

The adaptive skill of the human operator is now being simulated and reproduced by computer that have become more powerful and less expensive. This paper is concerned with an investigation of the effects of dynamic load of hydraulic oil on pressures with three different circuit(meter-in, meter-out and bleed-off). The experimental results showed that pressures increase with an increase in dynamic load in bleed-off circuit, but there is no variation of pressure in meter-in and meter-out circuits.

• 산업기술연구
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• 제24권B호
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• pp.29-36
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• 2004

The wind and wind-induced dynamic wind pressures fluctuate irregularly according to time and space. In this study, the proper orthogonal decomposition(POD) technique is applied to wind pressures acting on a tall tower model, and the following results are found: the along-wind and across-wind forces can be reconstructed by only four dominant POD modes, and the reconstructed errors are 4.71% and 22%, respectively for across-wind and along-wind directions. The physical meanings for dominant modes are also presented in the paper. The POD analysis can compress complex wind pressure data only by a few dominant modes and interpret spatio-temporal characteristics of wind pressure by novel way while existing statistical methods do not have such benefits.

• Journal of Advanced Marine Engineering and Technology
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• 제20권2호
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• pp.116-116
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• 1996

This paper is concerned with a method for calibrating five-hole probes of both angle-tube and prismatic geometries to measure local total and static pressures and the magnitude and direction of the mean velocity vector. Descriptions of the calibration technique, the typical calibration data, and an accompanying discussion of the interpolation procedure are included. The flow properties are determined explicitly from measured probe pressures using calibration data. Flow angles are obtained within the deviation angle of 1.0 degree and dynamic pressures within 0.03 with 95% certainty. The variations in the calibration data due to Reynolds number are also discussed. For the range of Reynolds number employed, no effect was detected on the pitch, yaw and total pressure coefficients. However, the static pressure coefficient showed change to cause minor variations in the magnitude of the calculated velocity vector. To account for these variations, average correction factors need to be incorporated into the static pressure coefficient.