• 한국지하수토양환경학회지:지하수토양환경
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• 제8권1호
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• pp.48-56
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• 2003

간단한 모형시추공을 이용한 전기전도도 측정실험을 실시하고 이로부터 시추공에서의 수리상수 결정에 관련된 제반기초 환경을 검증하고 실험에 의한 모델방정식을 유도하였다. 실험은 상대적으로 높은 염도를 공내수로 하고 증류수를 지하수를 사용하여, 지하수의 유입과 유출되는 유량을 일정하게 유지한 상태에서 전기전도도를 측정하는 것으로 이루어졌다. 관찰의 주 대상은 지하수의 유량, 공내수와 지하수 사이의 염도차 및 밀도차에 따른 공내에서의 전기전도도 변화 양상에 있었다. 실험결과, 공내에서의 시간에 따른 전기전도도 변화가 매우 일정한 양상으로 나타남을 보였으며, 유량과 전기전도도 변화율 사이에 양호한 상관관계가 얻어졌다. 이 결과는 향후 추가될 일반적인 수리상수와 검층수리 상수들의 비교연구로 모델방정식에 대한 검증이 이루어진다면, 희석모델에 근거한 전기전도도검층 기법이 수리 상수 결정을 위한 효과적인 방법이 될 수 있음을 보여 주었다.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.109-116
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• 2004

Bent-axis piston pump have been commonly used in hydraulic systems because of high pressure level, best efficiency, low shear force on pistons and low operating costs. The other side, they have a few demerits like that they have the relatively high number of moving parts and more discharge pressure ripples. Especially, the discharge pressure ripples bring about vibrations and noises in hydraulic system components such as connecting pipes and control valves, so that these deteriorate the stability and accuracy of the systems. Therefore, the hydraulic systems having the bent-axis piston pump require the methods to reduce the discharge pressure ripples. So, the purpose of this paper is to reduce the discharge pressure ripples by the phase interference of pressure wave and to develope the analysis model of the pumps to predict the discharge pressure ripples. In this paper, the analysis model of the bent-axis piston pump was developed using the AMESim software, and the reliability of that was verified by the comparison with the experimental results. The hydraulic pipeline with a parallel line was used as the method to generate the phase interference of pressure wave. the dynamics characteristics of the hydraulic pipeline with a parallel line were analyzed by a transfer matrix method. the usefulness of the phase interference of pressure wave was investigated through the experiment and simulation. The results from the experiment and simulation said that the phase interference of pressure wave by the hydraulic pipeline with a parallel line could reduce the discharge pressure wave of the pump well. The analysis model of the bent-axis piston pump developed in this paper and the method of the phase interference by the hydraulic pipeline with a parallel line are expected to be helpful to achieve the design of the pump and to reduce the discharge pressure wave of the pump effectively.

• 한국지반공학회논문집
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• 제34권3호
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• pp.5-12
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• 2018

불포화 투수계수 추정을 위하여 부정류 유출 및 흡입시험을 수행하였고 그 결과를 이용하여 역해석을 수행하였다. 부정류 수리특성을 이용하면 함수특성곡선 및 불포화투수계수를 정확하고 효율적으로 구할 수 있다. 본 연구에서 세가지 시료에 대한 실험을 세분화된 모관흡수력에 대하여 실행하고 시간에 따른 함수비의 변화를 정밀하게 측정하였다. 역해석과 실험결과를 비교한 결과, 시간에 따른 유량의 변화를 신뢰성 있게 계산할 수 있었다. 역해석의 해로 구한 함수특성곡선에서는 실험결과와 근사하게 나타났다. 불포화 투수계수곡선에서는 함수특성곡선으로부터 이론적으로 구한 곡선과 비교하였으나 역해석 결과와는 다소 차이를 보였다. 하지만 실험적 및 해석적 기법을 병행하여 획득한 불포화 수리적 거동이 실제거동에 부합된다고 판단된다.

• 한국해양공학회지
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• 제23권1호
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• pp.31-37
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• 2009

Coastal vegetation consists of rooted flowering marine plants that provide a variety of ecosystem services to the coastal areas they colonize. The attenuation of currents and waves and sediment stabilization are often listed among these services. From this point of view, artificial seaweed is an effective method of controlling sea bed sediment and stabilization without damaging the landscape or the stability of the coastline. A series of hydraulic experiments were performed in a wave channel with regular and irregular waves to examine the effect of artificial seaweed in relation to scouring and beach erosion prevention. Based on the results of these experiments, the coastal vegetation model is efficient against scouring and beach erosion.

• 한국해안해양공학회지
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• 제19권2호
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• pp.179-182
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• 2007

본 연구에서는 연안침식방지와 친수공간을 제공하기 위한 목적으로 새로 개발된 환경친화형 친수호안블록의 성능을 검증하기 위하여 반사율과 안정성을 대상으로 수리모형실험을 실시하였다. 실험 결과 블록의 현장적용 가능성이 있음을 확인하였다.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1555-1562
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• 2023

Natural circulation phenomena have been nowadays largely revisited aiming to investigate the performances of passive safety systems in carrying-out heat removal under accidental conditions. For this purpose, assessment studies using CFD (Computational Fluid Dynamics) and also 3D thermal-hydraulic system codes are considered at different levels of the design and safety demonstration issues. However, these tools have not being extensively validated for specific natural circulation flow regimes involving flow mixing, temperature stratification, flow recirculation and instabilities. In the present study, an experimental test case based on a small-scale pool test rig experiment performed by Korea Atomic Energy Research Institute, is considered for code-to-code and code-to-experimental data comparison. The test simulation is carried out using the FLUENT and the 3D thermal-hydraulic system CATHARE-2 codes. The objective is to evaluate and compare their prediction capabilities with respect to the test conditions of the experiment. It was observed that, notwithstanding their numerical and modelling differences, similar agreement results are obtained. Nevertheless, additional investigations efforts are still needed for a better representation of the considered phenomena.

• Journal of Biosystems Engineering
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• 제31권2호
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• pp.88-94
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• 2006

The market of rice transplanter has already been changed for riding and to be turned large size of chassis. Because an automation is rapidly expanded, It is strongly need to analyze a mechanism and develop a hydraulic circuit. In this study, we analyzed the mechanism of working equipment of rice transplanter for riding and developed hydraulic circuits. We proposed the operating mechanism of rice transplanter for riding through the mechanistic analysis of working equipment. And the simulation and experiment were performed. In order to up and down the working equipment of rice transplanter for riding, we designed the mechanism which was installed hydraulic circuit and hydraulic cylinder, and it was manufactured. The pressure of developed hydraulic circuit was set by 800 $N/cm^2$. In the field testing, the hydraulic response presented at 50 msec in the maximum driving velocity, 0.8 m/sec of rice transplanter for riding, and it was well performed. The results of experiments showed the system characteristics sufficient to use as the hydraulic mechanism for a rice transplanter for riding.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.237-242
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• 2000

In this paper, an experiment was carried out to measure the hydrodynamic oil pressure distribution in the clearance gap between a piston and cylinder. The results showed that the pressure distributions are highly affected by the eccentricity of the piston. Therefore present experimental method can be used to enhance the performance of hydraulic piston pumps. Further experimental studies for various operating conditions and improvement in data acquisition methods are required to obtain more accurate results.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제27회 춘계학술대회
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• pp.335-341
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• 1998

In this study, the dynamic characteritics in various loading methods for wear tester were investigated experimentally. As for the dead-weight, the pneumatic, and the hydraulic method, the load control performance against external disturbances was estimated under the several loading conditions like the different sliding speed, the varied normal load, and the misaligument. The hydraulic loading method showed the most stable loading performance of all the loading methods in the experiment.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.304-309
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• 2001

In this paper, the hydraulic oil pressure distributions are measured in the clearance gap between a stationary piston and moving cylinder apparatus. The results showed that the hydrodynamic pressure distributions are highly affected by the speed of cylinder and further experimental and analytical studies are required to obtain more accurate results. Therefore present experimental method can be used to enhance the performance of various hydraulic components adopting the piston-cylinder mechanism.