• Journal of Industrial Technology
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• v.25 no.A
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• pp.3-14
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• 2005

In order to accurately analyze the detailed hydraulic characteristics of the curved channel in the downstream of dam with the hydraulic structures such as bridge piers, RMA2 model which is one of two-dimensional models is applied to ChunCheon dam downstream curved channel. A series of hydraulic model tests are carried out for comparison studies. HEC-RAS model is also applied to the same site. There are no errors when velocities and water levels resulted from HEC-RAS model RMA2 model are compared with those of hydraulic model test on the straight channel. But, it is found that results of RMA2 model have a better agreement with those of hydraulic model test than those of HEC-RAS model on the curved channel with bridge piers. Additionally, RMA2 model can be predicted the eddy phenomena around bridge piers of the curved channel.

• International Journal of Highway Engineering
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• v.15 no.3
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• pp.45-52
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• 2013

PURPOSES : This study is to construct the regression models of drainage asphalt concrete specimens and to provide the appropriate coefficients of hydraulic conductivity prediction models. METHODS: In terms of easy calculation of the hydraulic conductivity from porosity of asphalt concrete pavement, the estimation model of hydraulic conductivity was proposed using regression analysis. 10 specimens of drainage asphalt concrete pavement were made for measurement of the hydraulic conductivity. Hydraulic conductivity model proposed in this study was calculated by empirical model based on porosity and the grain size. In this study, it shows the compared results from permeability measured test and empirical equation, and the suitability of proposed model, using regression analysis. RESULTS: As the result of the regression analysis, the hydraulic conductivity calculated from the proposal model was similar to that resulted from permeability measured test. Also result of RMSE (Root Mean Square Error) analysis, a proposed regression model is resulted in more accurate model. CONCLUSIONS: The proposed model can be used in case of estimating the hydraulic conductivity at drainage asphalt concrete pavements in fields.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.4
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• pp.93-99
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• 2008

The clutch is a subcomponent of the transmission that is designed to engage and disengage power flow between the engine and the transmission. Recently, the engine power of automobile has been continuously increased because of customer's demand for the bigger one. As the engine power is increased, the vibration transmitted to the hydraulic clutch operating system has been increased. Therefore the demand for the reduction of clutch pedal vibration during the operation of the clutch system has been increased. This paper describes the pressure pulsation reduction characteristics of the damper cylinder which is applied to the hydraulic clutch operating system. And the purpose of this study is to confirm the availability of a simulation model and investigating the test results of hydraulic clutch operating system. The test results are compared with the simulation results. Therefore it may be concluded that the simulation model and test results will be very useful f3r the design of hydraulic clutch damper cylinder.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.4
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• pp.429-440
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• 2015

In this study, model test equipment was developed to evaluate the hydraulic pressure reduction in appling the drainage shield tunnel and the model test for hydraulic pressure difference was performed in case of drainage and undrained conditions. In the result of model test, increase ratio of pore water pressure was decreased in drainage condition and total stress in drainage condition was smaller than that in undrained condition, so the hydraulic pressure was reduced by the groundwater inflow into the model tunnel. In the result of field instrumentation, the hydraulic pressure in the back ground of shield tunnel was small by 11~22% in comparison with the calculated hydraulic pressure ($r_w{\cdot}H$) in same groundwater level. In the result of model test and field instrumentation, it was appeared in drainage and undrained conditions that the difference between the theoretical hydraulic pressure and the real hydraulic pressure. It shows that it is possible to apply the reduced hydraulic pressure in applying the drainage shield tunnel and to reduce the segment section due to hydraulic pressure reduction.

• Journal of Drive and Control
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• v.15 no.3
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• pp.43-48
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• 2018

The hydraulic control valve, used in the CPB (cold-pad-Batch) cold dyeing system, passes through a pressurized material that absorbs the dye. The hydraulic control of the hydraulic control panel shall be driven in a uniform and precisely controlled manner, as it interferes directly with the dyschromatism. In this study, an acceleration test model was employed to verify the durability of the hydraulic control of the hydraulic control panel, which was manufactured by the scenic model, and the pre-roll angle was analyzed before the performance of acceleration test. Based on the change in the amount of deformation of the padder roll the durability of the padder roll was analyzed along with verification of the durability of the skin and the rubber coating in contact with the fabric. Furthermore, the accelerated test method used for hydraulic controlled multi-cell padder rolls was verified.

• Journal of Environmental Science International
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• v.9 no.1
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• pp.35-42
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• 2000

In this study, the movable bed model testing was carried out so as to analyze bed profile changes including predicting scouring and deposition of bed profile and to solve hydraulic problems affecting with bed and both-bank between upstream and downstream of intake weir in the Nakdong river channel. The movable bed model testing consists of fundamental test, movable model test and numerical analysis method respectively. The fundamental test was enforced to analyze relationship of discharge and sediment load in the tilting flume. When the movable model test was worked, it was shown that sediment budget between input sediment load and output sediment load was balanced exactly. As a result of movable model test, it was presented that scouring and deposition changes in quantities between the upstream and downstream of modification weir were less than those of nature and planning weir. Finally, numerical analysis method was operated by 1-dimensional bed profile changes model ; HEC-6 model so as to complement unsolving hard problems during movable model test. So, modification weir will sustained the stable bed profile changes than any other weirs in the study channel.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.5
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• pp.635-642
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• 2011

Hydraulic efficiency was a vital component in evaluating the disinfection capability of clearwell. Current practice evaluates these system based on the tracer test only. In this paper, CFD(Computational Fluid Dynamics) was applied on the clearwell for alternating or supplementing the tracer test. The baffle factor derived from the CFD modeling closely matched the values obtained from full scale tracer testing. And, for suggesting proper numerical model in clearwell; the turbulence model, discretization scheme, convergence criteria were investigated through separate simulation runs. The model validation was conducted by comparing the simulated data with experimental data. In the turbulence model, the realizable ${\kappa}-{\varepsilon}$ model and the standard ${\kappa}-{\varepsilon}$ model were found to be more appropriate than RNG ${\kappa}-{\varepsilon}$ model. The residuals of convergence criteria should be used as not $10^{-3}$ but $10^{-4}$ or $10^{-5}$. In discretization scheme, the difference of simulated values in 1st, 2nd, 3rd upwind scheme was found to be insignificant. Moreover, the result of this study suggest that CFD modeling can be a reliable alternative to tracer testing for evaluating the hydraulic efficiency.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.705-712
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• 2002

Geotextile tube is environmentally sustainable technology and has been applied in hydraulic and coastal engineering applications. Geotextile tube is composed in permeable fabrics and Inside dredged materials, and hydraulically or mechanically filled with dredged materials. These tube are generally about 1.0m to 2.0m in diameter, through they can be sized for any application. The tubes can be used solely, or stacked to add greater height and usability. Stacked geotextile tubes will create by adding the height necessary for some breakwaters and embankment, therefore increasing the usability of geotextile tubes. This paper presents the hydrodynamic behavior of stacked geotextile tube by hydraulic model tests. The hydraulic model test conducted by structural condition and wave conditions. Structural condition is installation direction to the wave(perpendicular band 45$^{\circ}$), and wave condition is varied with the significant wave height ranging from 3.0m to 6.0m. Based on the test results, the hydrodynamic behaviors such as structural stability, wave control capacity, and strain are interpreted.

• International Journal of Fluid Machinery and Systems
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• v.8 no.4
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• pp.318-326
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• 2015

A valve-less electro-hydraulic servo steering device (short: VSSD) for ships was chosen as a study object, and its mathematic model of hydraulic shock was established on the basis of flow properties and force balance of each component. The influence of system structure parameters, changing rate of motor speed and external load on hydraulic shock strength was simulated by the method of numerical simulation. Experiment was designed to test the hydraulic shock mathematic model of VSSD. Experiment results verified the correctness of the model, and the model provided a correct theoretical method for the calculation and control of hydraulic shock of valve-less electro-hydraulic servo steering device.

• Geomechanics and Engineering
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• v.25 no.2
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• pp.75-87
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• 2021

Because the hydraulic/mechanical behaviour of unsaturated soil is more complicated than that of saturated soil, one of the most important issues in modelling unsaturated soil is to properly couple its stress-strain relationship with its water retention characteristics. Based on the results of a series of tests, the stress-strain relationship and the changes in suction and saturation of unsaturated completely decomposed granite (CDG, also called Masado) vary substantially under different loading/hydraulic conditions. To precisely model the hydraulic/mechanical behaviour of unsaturated Masado, in this study, the superloading concept was firstly introduced into an existing saturated/unsaturated constitutive model to consider the structural influences. Then a water retention curve (WRC) model considering the volumetric change in the soil, in which the skeleton and scanning curves of the water retention characteristics were assumed to shift in parallel in accordance with the change in the void ratio, was proposed. The proposed WRC model was incorporated into the constitutive model, and the validity of the newly proposed model was verified using the results of tests conducted on unsaturated Masado, including water retention, oedometer and triaxial tests. The accuracy of the proposed model in describing the stress-strain relationship and the variations in suction and saturation of unsaturated Masado is satisfactory.