• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.353-360
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• 2000

We developed large diameter sampler (we called KICT type large diameter sampler) to obtain undisturbed clay and sand samples. In-situ test carried out in the In-Chon international airport and Kim-Hae. Also we obtained undisturbed sample with a hydraulic piston sampler in the nearly site and carried out unconfined compression test, consolidation test and triaxial test. The result, unconfined compression strength, secant modules, preconsolidation pressure and undrained shear strength of samples to obtain KICT type large diameter sampler are larger than that of samples to obtain hydraulic piston sampler. But failure strains and volume changes at the consolidation of samples to obtain KICT type large diameter sampler are smaller than that of samples to obtain hydraulic piston sampler

• 한국자동차공학회논문집
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• 제8권1호
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• pp.101-109
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• 2000

Occupant protection in the side impact of a car became one of the most important issues of car crashworthiness due to high injury level in a side impact crash. An accurate simulation of the side impact crash is an essential tool for the reduction of development time and cost for side impact safety system. This paper describes a new test methodology that can accurately generate the crash pulses of a vehicle and a door in a very cost-effective manner, and then evaluates the injury values of the dummy for the various sled pulses. This test methodology is simple and easy to approach because the door velocity is controlled by the hydraulic actuator and brake and the seat velocity is only adjusted by the friction force of the hydraulic brake. The superiority of the proposed test methodology is proven by the evaluation of dummy's injury values according to the change of the pressure of the hydraulic brake and by the application as a tool for the development of side airbag.

• 동력기계공학회지
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• 제13권5호
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• pp.18-24
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• 2009

This paper shows the result of development about the revolution system of azimuth thruster which of power is less than 250kW for small ship. Advanced Azimuth revolution system can revolve propeller and rudder from 360 degree so that this system for vessel maneuvering can be excellent of propulsion effectively. Fluid power control system for azimuth thruster is designed with PID control system by using CEMTool/SIMTool program. And the actuator used for servo valve can control rudder angle, pressure and direction. The first, We had a test for the angle control of revolution system. The result of angle control confirmed that it has the good efficiency from experiment result of time input degree $30^{\circ}$, $90^{\circ}$ and $180^{\circ}$. The second, We had to a test for the pressure characteristic of hydraulic motor. As a result, We confirmed the maximum pressure 3.5MPa and steady state 0.7MPa nom experiment result of time input degree $30^{\circ}$. In this paper, it is identified the pressure characteristic of hydraulic motor and angle control for azimuth thruster by AMESim, and it has been confirmed the usefulness of AMEsim modeling was verified by comparison between AMESim simulation results and experiments results.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2006년도 학술발표대회 논문집
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• pp.116-125
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• 2006

Piston assemblies, which are key components of hydraulic high pressure pumps & motors, are major failure products operating at high pressure and high speed, and the main failure mode is wearout of the shoe surface. To predict the actual life of piston assemblies. we require to find out the most sensitive parameters and establish related empirical formula. In this study, we analyzed the life of piston and shoe assemblies in accordance with variation of speed, pressure, and temperature to reduce the life test time, then analyzed the result of combined accelerated life test which is applied by high speed, speed pressure, and high temperature simultaneously, and finally developed combined accelerated life test model.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1537-1546
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• 2017

Many thermal-hydraulic tests have been conducted at the Korea Atomic Energy Research Institute for verification of the SMART (System-integrated Modular Advanced ReacTor) design, the standard design approval of which was issued by the Korean regulatory body. In this paper, the contributions of these tests to the standard design approval of SMART are discussed. First, an integral effect test facility named VISTA-ITL (Experimental Verification by Integral Simulation of Transients and Accidents-Integral Test Loop) has been utilized to assess the TASS/SMR-S (Transient and Set-point Simulation/Small and Medium) safety analysis code and confirm its conservatism, to support standard design approval, and to construct a database for the SMART design optimization. In addition, many separate effect tests have been performed. The reactor internal flow test has been conducted using the SCOP (SMART COre flow distribution and Pressure drop test) facility to evaluate the reactor internal flow and pressure distributions. An ECC (Emergency Core Coolant) performance test has been carried out using the SWAT (SMART ECC Water Asymmetric Two-phase choking test) facility to evaluate the safety injection performance and to validate the thermal-hydraulic model used in the safety analysis code. The Freon CHF (Critical Heat Flux) test has been performed using the FTHEL (Freon Thermal Hydraulic Experimental Loop) facility to construct a database from the $5{\times}5$ rod bundle Freon CHF tests and to evaluate the DNBR (Departure from Nucleate Boiling Ratio) model in the safety analysis and core design codes. These test results were used for standard design approval of SMART to verify its design bases, design tools, and analysis methodology.

• 유공압시스템학회논문집
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• 제4권1호
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• pp.18-24
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• 2007

The continuously variable transmission (CVT) of which speed ratio can change continuously in a fixed range has the benefits of low fuel consumption and exhaust gas because it enables the engine of a vehicle to operate in a high efficiency range regardless of vehicle speed. The speed ratio of belt type CVT is controlled by adjusting line pressure. The one of the line pressure control methods, mechanical-hydraulic control is usually adopting VDT's control method, in which the secondary solenoid valve has two functions both a regulator and a line pressure controller. However, this control method could not show the high performance of CVT with optimal driving capability because of the limitation of simple control algorithm, and it could not gain market share sufficiently in spite of the advantage of CVT with low fuel consumption. On the other hand, the electro-hydraulic control method gives the enhancement of power performance and low fuel consumption by implementing various driving mode using the proportional control or PWM control. The key of CVT technique is to develop a control algorithm of the electro-hydraulic solenoid valve in order to implement the speed ratio efficiently. In this paper, the line pressure control algorithm is proposed and the hydraulic system is controlled using metal belt type CVT test rig and the embedded ECU platform.

• 농업과학연구
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• 제40권3호
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• pp.237-241
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• 2013

This study started to export an orchard tractor to Europe under the situations that R&D activities for orchard tractor were marginal and even it was not produced. The R&D for orchard tractor has been progressed and the most of it is accomplishing the goal. In this study, the durability of clutch friction part was tested for F/R clutch and moment of inertia of PTO clutch, and it was compared with the design criteria of transmission of tractor. According to the results of inertia test of F/R clutch, hydraulic pressures of clutch satisfied $1,961.33{\pm}196.13kPa$ of design criteria, and the variations of torque for forward and reverse operation were relatively constant. Therefore, it was found that the durability of clutch friction part was stable and reliable. Test results showed that the main hydraulic pressures were maintained $1,961.33{\pm}196.13kPa$ during the tests of moment of inertia of PTO clutch, and when it was operated, the hydraulic pressures were reached $1,961.33{\pm}196.13kPa$. Therefore, it was found that the hydraulic pressures of PTO satisfied the design criteria. By the results that the time of the hydraulic pressures of PTO reaching main hydraulic pressure, and that of torque values restoring to the original was same as the time of the first gear of PTO reaching the maximum rotational speed, it was found that PTO could transfer power to attachments as it was designed.

• Journal of Mechanical Science and Technology
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• 제19권8호
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• pp.1621-1631
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• 2005

In this paper, making the best use of the features of the electro-rheological (ER) valve, a two-port pressure control valve using ER fluids is proposed and manufactured. The ER-Valve characteristics are evaluated by changing the intensity of the electric field and the number of electrode. As only with electrical signal change to the ER-Valve in which ER fluid flowing, ER fluid flow is controlled, so development of simple ER-Valves have been tried. The ER-Valves and pressure drop check method are considered to be applied to the fluid power industry. Using the manufactured pressure control valve, a one-link manipulator with FHA (Flexible Hydraulic Actuator) is driven. As a result, it is experimentally confirmed that the pressure control valve using ER fluids is applicable to use in driving actuator. If it applies characteristics of the ER fluids, it will be able to apply in the control system for the ER Valve which occurs from industrial controller. After having durability test, shear stress increased regularly because of starch particles crushed by pump and particle size that was almost the same. Moreover, Ra of copper electrode increased about 1.56 times rather than before those of performing durability test, and Rz increased about 2.2 times.

• Journal of applied mathematics & informatics
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• 제41권2호
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• pp.295-309
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• 2023

The Richards' equation attracts the attention of several scientific researchers due to its importance in the hydrogeology field especially porous soil. This work presents a numerical method to solve the two dimensional Richards' equation. The pressure form and the mixed form of Richards' equation are solved numerically using a bivariate diamond finite volumes scheme. Euler explicit scheme is used for the time discretization. Different test cases are done to validate the accuracy and the efficiency of our numerical model and to compare the possible numerical strategies. We started with a first simple test case of Richards' pressure form where the hydraulic capacity and the hydraulic conductivity are taken constant and then a second test case where the hydrodynamics parameters are linear variables. Finally, a third test case where the soil parameters are taken according the Van Gunchten empirical model is presented.

• International Journal of Automotive Technology
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• 제3권2호
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• pp.57-62
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• 2002

It is well known that the entrained air in oil causes appreciable reduction in the stiffness of hydraulic systems. It makes the response delay of the systems and sometimes destroys the stability. Because the hydraulic systems of automatic transmissions are operated in relatively low pressure and high temperature, it is very important to analyze the effects of the air included in automatic transmission fluid. However, it is difficult to derive the generalized model to describe the effective bulk modulus theoretically or measure it in actual operating conditions of automatic transmissions. This paper reviews previous studies of the air effects in hydraulic systems and the measurement techniques of the effective bulk modulus in operating conditions. Based on this work, the theoretical model with moderate complexity and the measurement technique of the effective bulk modulus considering entrained air effect at real operating conditions are suggested. Our paper also shows that the quantity of the entrained air in the automatic transmission fluid can be estimated from the experimental results.