• International Journal of Fluid Machinery and Systems
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• 제3권1호
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• pp.80-90
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• 2010

The cavity oscillation with swirling flow in hydraulic power generating systems was studied by a simple experiment and numerical simulation. Several types of fluctuation were observed in the experiment, including the cavitation surge caused by the diffuser effect and the vortex precession by the swirling flow. Both cavitation surge and vortex precession were simulated by CFD. Detailed flow structure was examined through flow visualization and CFD.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.498-507
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• 2008

The mixture of bentonite powder and water is generally used to maintain the stability of excavation surface during the construction of vertical cutoff walls. The filter cake on the sidewall surface is the result of filtration of slurry into the adjacent soil formation. The filter cake is believed to have a very low hydraulic conductivity compared to that of the cutoff wall. This paper evaluates hydraulic conductivities of bentonite filter cakes set up with three types of bentonites under various pressure levels. A modified fluid loss test was employed in this experiment. Theory of filtration process was reviewed to explain the procedure in the present experiment. Hydraulic conductivity of the filter cakes with consideration of the filter medium resistance was evaluated. The results of the experiment with two calculation methods and discussion are presented to show the efficiency of the modified fluid loss test.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1502-1511
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• 2008

The mixture of bentonite powder and water is generally used to maintain the stability of excavation surface during the construction of vertical cutoff walls. The filter cake on the sidewall surface is the result of filtration of slurry into the adjacent soil formation. The filter cake is believed to have a very low hydraulic conductivity compared to that of the cutoff wall. This paper evaluates hydraulic conductivities of bentonite filter cakes set up with three types of bentonites under various pressure levels. A modified fluid loss test was employed in this experiment. Theory of filtration process was reviewed to explain the procedure in the present experiment. Hydraulic conductivity of the filter cakes with consideration of the filter medium resistance was evaluated. The results of the experiment with two calculation methods and discussion are presented to show the efficiency of the modified fluid loss test.

• 한국산학기술학회논문지
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• 제18권10호
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• pp.24-35
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• 2017

본 논문은 하천 제방의 침투방지공법으로 일본 미쓰야마 하천 국도 사무소에서 제시한 월륜 공법에 대한 효용성을 연구한 것으로, Hydraulic well의 현장 적용성과 시공성 개선, 침투압 분포 특성을 파악하기 위하여 대형 제방실험과 침투 해석을 수행하였다. 대형제방실험의 방법은 제외지 수위를 재현하여 제방을 포화시킨 후 제방의 간극수압계 변화를 감지, hydraulic well의 내부 수위를 0.1 m ~ 0.7m로 변화하고 이때 간극수압계를 통해 측정된 간극수압을 비교하여 침투압의 변화를 확인하였다. 대형 제방실험은 hydraulic well의 설치 지점에 따라 두 가지 방법으로 수행하였다. 대형 제방실험결과, hydraulic well의 내부 수위 변화에 따라 최대 37%의 침투압 저감 현상이 발생하는 것으로 평가되었다. 대형 제방실험과 침투 해석의 간극수압을 비교한 결과 거의 유사한 경향이 나타났다. hydraulic well의 내부 수위 변화와 산정된 간극수압의 변화도 비슷한 양상을 보였으나, 심도가 깊어짐에 따라 대형 제방실험결과보다 침투 해석의 간극수압이 더 크게 산정되었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.167-174
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• 1997

In this paper, the mathematical model of the hydraulic control valve is formulated, that is, this dynamic modeling which includes the motion equations and continuity equations can analyze the dynamic characteristics of the hydraulic control valve. The control valve for the transmission has the Over Speed Protection to protect a hydraulic travel motor. Therefore, this simulation shows the over speed protection and researches the main design parameters. The results of the computer simulation were assured through the experiment. From the comparison between both results, it is shown that this simulation program is useful and effective.

• 산업기술연구
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• 제24권B호
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• pp.123-131
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• 2004

The existing of developed scour Equation have a very different value by boundary condition, hydraulic condition and bed condition. Therefore it may give rise to a serious trouble if it make a wrong application of the scour Equation. So this research of purpose is the predicting of scour depths, the method is that analysis river of feature and hydrauric feature for river in kangwondo young-seo region. And hydrauric model experiment of Scour phenomenon execute after the existing of calculate scour depths equation analysis sensitivity, assort a practical.

• 한국생산제조학회지
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• 제8권4호
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• pp.38-44
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• 1999

This paper primarily directed toward analyzing the frequency response in hydraulic pipe lines with a small diameter. The exact solution to the frequency response is obtained by using the complicated transfer function. The discrepancy with the exact and the approximate is small so the approximation solution is adopted to compare the experimental results with the theoretical analysis. In this experiment the input frequency was generated by the frequency generator with the ball valve and speed controller. In order to compare the theoretical were forms with the experimental ones the trace obtained from the oscilloscope is photographed, The diameter the length of lines and input pressure amplitude are varied to investigate their effects,. the experiment results show that th values of dimensionless parameter are very affected to the phase delay and guide response time in the design of pressure manifold to measure the pressure of hydraulic pipelines.

• 대한기계학회논문집
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• 제12권2호
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• pp.215-220
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• 1988

본 연구에서는 비례제어하였을 때 정정한 시스템(K=1.0)과 진동 현상을 보이는 시스템(K=20)을 제어대상으로 설정한 후, 관측기의 상태변수를 이용하여 이들을 피이드백 제어하였을 때 응답 특성이 개선될 수 있는지를 조사하고자 한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.133-137
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• 2007

As the waterpower generation plant, the subject of this Study, is a facility that produces plenty of electricity corresponds to $196{\sim}240GWh$ annually, and in its generation process it creates a loud noise when the turbine related to the hydraulic turbine dynamo revolves, and since such loud noise must be transmitted to the dynamo room and amplified, it is effecting a lot of influences to the adjacent office and space. In such viewpoint, this Research, based on the soundproof measure presented at the preceding research, has attempted to evaluate about the effect of noise-reduction countermeasure against the hydraulic turbine dynamo using Auralizational Technique through Psycho-Acoustics Experiment. It deems that such result could be applied hereafter as the useful material when setting up a soundproof countermeasure for the hydraulic turbine dynamo room in dam.

• 한국기계가공학회지
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• 제2권4호
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• pp.46-52
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• 2003

For position control of electro-hydraulic servo system, single rod cylinders and double rod cylinders are used. Single rod cylinders have simple structure for manufacturing but different volume ratio of two sides induce to non-linearity in process of then mathematical modeling. So only with conventional PID control method it is difficult to control single rod cylinders precisely. For mole precise position control of single rod cylinders, a controller which is inserted a velocity feedback PID controller and MRAC controller are proposed. With experiment control performances of three control methods are compared. In case of experiment, for external varying load to the system, a hydraulic cylinder and a pressure control valve are used. In conclusion a MRAC is considered a suitable control method for external varying load.