• Journal of Biosystems Engineering
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• 제24권5호
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• pp.383-390
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• 1999

When a tractor travels slope lands, problems of operator safety and the reduction of job efficiency usually occur. Therefore, maintaining the tractor body being horizontal is critical to improve the security of traveling and the job performance. An experiment was made in a soil bin using the experimental model system built and equipped with a leveling control system. Adaptability of the control system was tested and investigated by analyzing system response in time and frequency domains. Control response time of hydraulic cylinder with 10lpm flow rate on a step input of 10$^{\circ}$slope was about 0.42sec. And it showed a linearly increasing trend without any hunching state. A steady state error of 0.6$^{\circ}$occurred but it was negligible. The hydraulic control system showed a little phase differences within the range of 0.4Hz input frequency. The experimental model showed that implementation of the proposed tractor control system to on slope lands tractor was feasible.

• 한국수자원학회논문집
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• 제36권5호
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• pp.811-821
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• 2003

본 연구에서는 수리모형실험을 실시하여 방류관의 흐름특성을 분석 방류관 설계의 적정성을 검토하는데 있다. 수리모형실험 결과 기본계획의 방류관 통수능은 과소설계 되었고, 이를 토대로 설계 변경한 기본설계의 방류관 통수능 설계치는 실험치와 거의 일치하여 적절하게 설계되었음을 알 수 있었다. 또한 방류관 부압발생 여부 및 종단형상의 적정성을 검토한 결과 허용치 이내 값이 발생되어 적절한 것으로 판명되었다. 이러한 과정을 토대로 기본설계의 방류관 규모 및 위치가 적절하였음이 검토되었다.

• 방사선산업학회지
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• 제5권1호
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• pp.87-93
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• 2011

A laboratory experiment using a radioisotope was performed to analyze the characteristics of transport and diffusion of a pollutant released from industrial plants. A wave hydraulic model based on the similarity theory was constructed and used to reappear the tidal wave in the laboratory. Two-dimensional numerical models were used to reproduce the results of a wave hydraulic model. The measured and calculated concentrations were compared with the same conditions. As a result of the comparative study, the time of maximum concentration showed slight difference between them, but the values of maximum concentration were relatively well agreed.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.1126-1135
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• 2022

The MARS code has been assessed for the prediction of onset of flow instability (OFI) in a vertical channel. For assessment, we built an experiment database that consists of experiments under various geometry and thermal-hydraulic condition. It covers pressure from 0.12 to 1.73 MPa; heat flux from 0.67 to 3.48 MW/m²; inlet sub-cooling from 39 to 166 ℃; hydraulic diameters between 2.37 and 6.45 mm of rectangular channels and pipes. It was shown that the MARS code can predict the OFI mass flux for pipes reasonably well. However, it could not predict the OFI in a rectangular channel well with a mean absolute percentage error of 8.77%. In the cases of rectangular channels, the error tends to depend on the hydraulic diameter. Because the OFI is directly related to the subcooled boiling in a flow channel, we suggest a modified subcooled boiling model for better prediction of OFI in a rectangular channel; the net vapor generation (NVG) model and the modified wall evaporation model were modified so that the effect of hydraulic diameter and heat flux can be accurately considered. The assessment of the modified model shows the prediction of OFI mass flux for rectangular channels is greatly improved.

• 드라이브 ㆍ 컨트롤
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• 제16권1호
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• pp.7-13
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• 2019

The objective of this study was to present a damped pneumatic suspension, a bike fork suspension, which can adapt itself to incoming road excitations is presented in this paper. It consists of a hydraulic damper and a pneumatic spring in parallel with a linear spring. The study also proposed a variable and switchable orifice, in the hydraulic damper, to select appropriate damping property. Hydraulic-pneumatic circuit model for the bike fork suspension was established based on AMESim, in order to predict its performance. In addition, elastic-damping characteristics of the fork such as spring constant and viscous damping coefficient were computed and compared, for validation, with those evaluated by experiment using the universal test machine. Through simulation analysis and test, it was established that the hydraulic-pneumatic circuit model is effective and practical for development of future MTB suspensions.

• 한국해안해양공학회지
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• 제14권3호
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• pp.240-246
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• 2002

타원형 천퇴해역에 대한 규칙파 및 일방향 불규칙파의 전파변형에 대한 수리모형실험을 수행하였다. 수리모형실험은 비쇄파조건의 규칙파와 천퇴의 정상부에서 부분쇄파가 발생하는 일방향 불규칙파를 대상으로 수행되었다. 수리모형실험 조건에 대해 포물형근사식을 적용한 수치해석을 수행하여 실험결과와 비교하였다.

• 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.

• 산업기술연구
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• 제26권B호
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• pp.63-71
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• 2006

The concerned object of the construction industry is environment. It is one of the main purposes of today's construction that human can live reasonably in nature. This study is about the fish-road connecting hydraulic structure in the river with nature. Chapter 2, starting with the general investigation about fish-road and helps comprehension for relatively general fish-road such as necessity, establishment purpose, history, study example, relating domestic law, design condition, consideration and form of fish-road. Chapter 3, containing the present condition of fish-road facilities in Gangwon-Do and thoughts of the problems and general countermeasures of existing fish-road. Chapter 4, Having Examined compatibility by amount of flowing water through hydraulic model test in the Ice harbor I-type model. chapter 5, Analyzation and arrangement to efficient establishment plan of fish-road and the result of the hydraulic model experiment to be beaconed a little in forward fish-road study. In the hydraulic model test result, when we suppose establishment of 1~3 in slope of 1/20, could know that applicable drought flow of the river is $0.06{\sim}3.0m^3/sec$ in case of Ice harbor I-type which transforming Ice harbor that was invented as studying project of the Ministry of Environment.

• 한국자동차공학회논문집
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• 제18권4호
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• pp.107-114
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• 2010

Coupling systems for trains need more complicated buffer equipments than existing systems because the recent tendency of the regulations enforces trains to be safe for collisions even when the driving speed is higher than before. Using hydraulic buffer is an effective way to satisfy the requirement while it causes the increase of the cost for the coupling system. In this study, we introduce the methodology to build a simulation model for the hydraulic buffer, which could be installed into the coupling systems. In the simulation model of the hydraulic buffer, the reacting force is determined by both buffer stroke and speed whereas the elastic buffer model is designed by using only the buffer stroke in other studies. The simulation results with the advanced hydraulic buffer model shows that the simulating results can be close the real experimental results around 10%, and, if we considers friction forces, the simulation calculates the maximum force within 10% comparing to the experimental.

• 한국방재학회 논문집
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• 제5권1호
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• pp.63-68
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• 2005

영상 해석을 이용한 유속 측정 방법인 LSIV를 합류점의 수리 모형 실험에 적용하였다. LSIV에 의해 측정된 표면 유속은 유속계에 의해 측정된 평균 유속과 상당히 유사한 결과를 나타내었다. 일반적인 유속계는 순간적인 지점 유속만을 나타내기 때문에 전체적인 유속장을 살피는 데 어려움이 있으나, LSIV는 전체적인 흐름장의 양상을 한 눈에 살펴 볼 수 있는 좋은 도구이다. 특히 합류점이나 교각 주변부와 같이 흐름이 국부적으로 변화가 심한 경우 LSIV는 적절한 실험 도구가 될 수 있을 것이다.