• 유기물자원화
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• 제17권1호
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• pp.73-79
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• 2009

수리전도도는 다공성매체 시스템의 중요한 특성인자이다. 수리전도도를 측정하는 방법은 실외측정방법과 실내측정방법이 있다. 수리전도도의 실내측정은 일반적으로 투수측정기를 이용한다. 기존의 투수측정방식으로 산정한 수리전도도는 경계흐름의 영향을 고려하지 않고 모든 유체가 수직으로 이동한다는 가정으로 결정되었다. 하지만 실제 토양에서 유체는 수직, 좌우 방향으로 이동할 수 있다. 본 연구에서는 경계흐름을 배제한 투수계를 이용하여 경계흐름이 수리전도도에 미치는 영향을 평가하였다. 실험결과 기존방식으로 산정한 수리전도도에 비해 경계흐름을 배제한 수리전도도가 약 1/3에 해당하였다. 투수측정기를 이용한 수리 전도도 측정에 있어 경계흐름에 대한 영향을 고려한 수리전도도 결정이 필요하다. 또한 토양 입경과 계면활성제가 수리전도도에 미치는 영향을 파악하였다. 토양입경과 수리전도도는 비례하는 것으로 나타났으며 계면활성제는 수리전도도를 감소시키는 것으로 확인되었다. 계면활성제 농도가 증가할수록 수리전도도는 보다 많이 감소하였다. 수리전도도를 결정하는 물리적 특성을 평가한 결과 유체의 점도가 가장 큰 영향을 미치는 것으로 나타났다.

• Journal of Biosystems Engineering
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• 제16권4호
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• pp.355-362
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• 1991

The objective of this study was to develop an electronic-hydraulic depth control system. Simulation was carried out to investigate the responses of the control system, and indoor experiments were carried out to confirm the simulation results of the control system. Field experiments were carried out to compare the newly-developed electronic-hydraulic depth-control system with the existing mechanical-hydraulic position control system in terms of the performance of depth control. The electronic-hydraulic depth control system showed better performance than the existing mechanical-hydraulic hitch control system for the forward speeds of tractor less than 7 km/h. It is concluded that the new control system could be adapted to the existing tractors with slight modifications to the conventional mechanical-hydraulic hitch control systems.

• The Journal of the Acoustical Society of Korea
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• 제21권1E호
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• pp.42-48
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• 2002

In this paper, a computer simulation method is presented far the dynamic analysis of a hydraulic engine mount system. The hydraulic engine mount system controls the damping characteristics using the viscosity of fluid flow. The complex stiffnesses of the main rubber for the hydraulic engine mount system are computed using a finite element analysis. The equations of motion considering the parameters of the hydraulic engine mount system are derived. To investigate the effects of the hydraulic engine mount system, the computer simulation running over a typical rough road is carried out using a vehicle dynamic model. These results are compared with those of the conventional rubber mount system.

• 항공우주시스템공학회지
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• 제4권2호
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• pp.16-20
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• 2010

In General, the hydraulic system of T-50 Advanced Trainer is applied to flight control system, wheel & Brake system and fuel system for aircraft operation. The hydraulic system is operation with pressure of 3000psi. and many mechanical parts which is operated by hydraulic system has been stressed in incomplete environment same as heat and friction. for example, Oil leakage had occurred in the shutoff valve of FFP used in a certain period of time. After study, The crack progressed by fatigue due to the irregular hydraulic pressure and vibration has been identified as the reason of oil leakage. This paper presents life cycle extension plans of FFP shutoff valve by configuration improvements of shutoff valve and FFP hydraulic motor.

• 한국자동차공학회논문집
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• 제14권4호
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• pp.32-38
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• 2006

A clutch hydraulic system for automotive manual transmissions transfers hydraulic pressure generated by driver's pedal manipulation to the clutch mechanism. The foot effort when the clutch pedal is pushed is different than that when the clutch is returned. The effort or load difference, called hysteresis, is caused by the friction produced between rubber seal and inner wall inside the hydraulic cylinder. This clutch pedal travel foot effort hysteresis is essential for a clutch hydraulic system design and analysis. The dynamic model for a clutch hydraulic system is developed and a simulation analysis is performed to estimate the fiction coefficient as a function of the cylinder pressure. The simulation result is then compared to the measurements obtained from a clutch hydraulic system tester to ensure the reliability of the dynamic model and the coefficients estimated. Also the estimated friction coefficients at various pressure values are compared to those reported by an independent study.

• 한국공작기계학회논문집
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• 제15권5호
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• pp.29-36
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• 2006

The hydraulic excavators are mainly applied for excavating, public works, quarrying, etc. In some of the construction site, however, they are used for crane works of relatively light materials, although the crane works by the hydraulic excavators are forbidden by law due to the safety reasons. The major construction equipment companies in forward countries have been developing the new systems, e.g. crane works by the hydraulic excavators, and they are working in the construction site. Therefore, the new system of crane works by the hydraulic excavators should be developed for the domestic construction site in order to prevent the accident. In this paper, the fundamental study and experiment are accomplished for the crane system application on the hydraulic excavators.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.585-588
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• 1995

In this study, the analysis of the static and dynamic characteristics of the load-sensitive hydraulic pump control system used in the hydraulic excavator was performed by hydraulic circuit ananlysis program. Thess results was verified by the experimental data of the hydraulic excavtor system. The responses on effective parameters of system at the controllable region and the pressure variation of the pump used in hydraulic excavator system was studied to enhance the static performace of the system. the parameter enhance dynamic sharacteristics was considerd.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 추계학술발표회
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• pp.208-211
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• 2001

Geosynthetic Clay Liners (GCLs) have been used for the applications of the hydraulic containment system in landfill due to inexpensive costs, simple workability and distinguished ability as a barrier material. However, bentonite of GCLs is easy to be damaged by the chemical solutions. Thus, there is a need to evaluate the potential susceptibility of GCLs causing Increase the hydraulic conductivity when GCLs are exposed to raw leachate and dissolved humic substances from landfill leachate. The hydraulic conductivity tests were performed with flexible-wall permeameter (the falling -headwater/rising -tailwater procedure) in order to verify the potential susceptibility of GCLs. The values of the hydraulic conductivity conducted with raw leachate as a permeant liquid increased considerably; however, The change of the hydraulic conductivity in the case of humic and fulvic acid were not worthy of notice. As the results of swelling tests of bentonite, however, humic substances can affect badly on the dispersion behavior of bentonite. These results indicate that humic substances dissolved in leachate could reduce the hydraulic conductivity of GCLs in landfill.

• 한국환경과학회지
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• 제6권1호
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• pp.17-24
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• 1997

The objective of this study was to examine the transient response to hydraulic shocks in an Inverse fluidized bed bioflm reactor(IFBBR) for the treatment of apartment sewage. The hydraulic shock experiments, when the system were reached at steady state with each HRT 12, 7, and 4hr, were conducted by chancing twice HRT per day during 3days. The SCOD, SS, DO, and pH of the effluent stream were increased with hydraulic shock, but easily recovered to the steady state of pre-hydraulic shock condition. In spite of hydraulic shock, there were not much variation of biomass concentration, biofilm thickness and biofilm dry density.

• 기계와재료
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• 제11권2호통권40호
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• pp.53-61
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• 1999

The paper describes a characteristics analysis for cushion pressure and cushion stroke time at hydraulic cushioning cylinder. In hydraulic cushioning cylinder, an inertia exaggerates a kinetic energy at a reciprocation that collide with an end of stroke and generate a destructive shock, noise and vibration within the structural and operating member of machine of equipment. In order to reduce which cause to undesirable noise, vibration and fatigue in hydraulic control system, it is indispensible measure a cushion parameters at cushion region of hydraulic cushioning cylinder. A cushioning device is applied to absorb high impact energy and to decelerate a fast travelling object, too. At an experimental results, it turns out that cushion pressure is mainly a function of the external load and cylinder input flowrate rather than the supply pressure.