• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.211-212
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• 2004

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.4
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• pp.164-173
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• 2006

In the electro-hydraulic injector for the common rail Diesel fuel injection system, the injection nozzle is being opened and closed by movement of a injector's needle which is balanced by pressure at the nozzle seat and at the needle control chamber, at the opposite end of the needle. In this study, the piezo actuator was considered as a prime movers in high pressure Diesel injector. Namely a piezo-driven Diesel injector, as a new method driven by piezoelectric energy, has been applied with a purpose to develop the analysis model of the piezo actuator to predict the dynamics characteristics of the hydraulic component(injector) by using the AMESim code. Aimed at simulating the hydraulic behavior of the piezo-driven injector, the circuit model has been developed and verified by comparison with the experimental results. As this research results, we found that the input voltage exerted on piezo stack is the dominant factor which affects on the initial needle behavior of piezo-driven injector than the hydraulic force generated by the constant injection pressure. Also we know the piezo-driven injector has more degrees of freedom in controlling the injection rate with the high pressure than a solenoid-driven injector.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.4
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• pp.93-99
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• 2013

Parts and structures such as piston rod and knuckle joint for the use of hydraulic cylinder are often welded together in some fashion, usually due to cost and process effectiveness. Welding strongly affects the material by the process of heating and subsequent cooling as well as by the fusion process with additional filler material. Furthermore, a weld is usually far from being perfect, containing inclusions, pores, cavities, undercuts etc. As a consequence, fatigue failures appear in welded structures mostly at the welds rather than in the base metal, even if the latter contains notches. For this reason, fatigue analyses are of high practical interest for all welded structures under the action of cyclic loads. This paper describes the influence of welding parameters, material combinations and heat treatment on the fatigue behavior of welded cylinder rod. In addition, statistical characterization of stress-life response in weldment of hydraulic cylinder rod are presented.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.122-128
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• 2002

In this paper dynamic responses of an engine, which is supported by hydraulic mount, to throttle tip-in/Tip out are analyzed. Because the hydraulic mounts have non-linearity that the characteristics of stiffness and damping vary with frequencies, it is difficult to analyze the dynamic behavior of an engine using general integral algorithms. Convolution integral and relationship between unit impulse response functions and frequency response functions are therefore used to simulate the transient behaviors of an engine indirectly. In time domain, impulse response functions are calculated by two-side discrete inverse courier transform of frequency response function achieved by laplace transform of equations of motion. Considering the fact that the shapes of behavior of an engine simulated by the proposed method are in good agreement with test results, it is confirmed that the proposed method is very effective for the analysis of transient response to throttle tip-in/out of an engine with hydraulic mounts.

• International Journal of Fluid Machinery and Systems
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• v.4 no.2
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• pp.289-306
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• 2011

In the development of very high head pumped storage projects, one of the critical problems is the strength of pumpturbine runners. Data obtained by stress measurements of high head pump-turbine runners indicated that dynamic stress due to the vibration of runner might be detrimental, possibly to cause fatigue failure, if the runner were designed without proper consideration on its dynamic behaviour. Numerous field stress measurements of runners and model tests conducted with hydrodynamic similarity revealed that the hydraulic excitation force developed by the interference of rotating runner blades with guide vane wakes sometimes would induce such heavy vibration of runner. Theoretical and experimental investigations on both the hydraulic excitation force and the natural frequencies of runner have been conducted to explore this forced vibration problem.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.489-494
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• 2002

This paper presents hydraulic model which can capture the hysteric damping force behavior of ER damper. A flow mode rue ER damper is manufactured, and its field-dependent damping forces are measured. Newly proposed hydraulic model which derived from physical hydro-mechanical parameters of ER damper are conventional Bingham model are investigated to represent the field-dependent damping force characteristics of ER damper. After principal parameters of two models are estimated from the measured damping forces data, the force vs velocity hysteresis cycles are then reconstructed. The results show that the proposed hydraulic model can capture the hysteresis behavior of ER damper accurately.

• International Journal of Automotive Technology
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• v.8 no.5
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• pp.615-622
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• 2007

In this study, a Coupled Computational Fluid Dynamics(CFD) and Finite Element Analysis(FEA) method are used to predict and evaluate the performance of an automotive shock absorber. Averaged Navier-Stokes equations are solved by the SIMPLE method and the RNG $k-\varepsilon$ is used to model turbulence. CFD analysis is carried out for different intake valve deflections and piston velocities. The force exerted on the valve in each valve deflection is obtained. The valve deflection-force relationship is investigated by the FEA method. The force exerted on the valve in each piston velocity is obtained with a combination of CFD and FEA results. Numerical results are compared with the experimental data and have shown agreement. Dependence of valve deflection as a function of piston velocity is investigated. Effects of hydraulic oil temperature change on valve behavior are also studied.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1571-1580
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• 2008

Subsea tunnels that link land to island and among nations for transportation, efficient development of limited surface and pursuit of economic development should be designed to support pore water pressure on the lining. It is generally constructed in the bed rock of the sea bottom. When the tunnel excavation face meets fractured-zones below sea bottom, collapse may occur due to an increase of pore water pressure and large inflow. Such an example can be found in the Norwegian subsea tunnel experiences in 1980's. In this study hydraulic behavior of tunnel heading is investigated using numerical method based on the collapse of Norwegian subsea tunnel. The effect of pore water pressure and inflow rate were mainly concerned. Horse-shoe shaped model tunnel which has 50 m depth from the sea bottom is considered. To evaluate hydraulic performance, parametric study was carried out for varying relative permeability. It is revealed that pore water pressure has increased with an increase of sea depth. Especially, at the fractured-zone, pore water pressure on the lining has increased significantly. Inflow rate into tunnel has also increased correspondingly with an increase in sea depth. S-shaped characteristic relation between relative permeability and normalized pore water pressure was obtained.

• Journal of Drive and Control
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• v.19 no.1
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• pp.26-33
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• 2022

This study dealt with a self-propelled spinach harvester, which is capable of carrying out sequential harvesting work. This study aimed to find the cause of the harvester's occasional performance deterioration, which occurs in the process of simplifying the hydraulic circuit, using a multi-domain analysis model. The study was carried out in the following manner. First, a hydraulic system analysis model, which combines linear motion, rotary motion, hydrodynamic behavior, and an electrical signal, was developed through SimulationX software, specialized in multi-domain analysis. Second, a scenario for single behavior and coupled behavior was set out on an actuator basis. Third, the flow rate of the hydraulic system, which is not required for the movement of the actuator, was quantitatively analyzed. The results showed that a change in oil temperature was the cause of the harvester's occasional performance deterioration. And the higher the oil temperature, the more serious the performance deterioration, especially as the number of actuators operated simultaneously was small.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.601-608
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• 2011

In order to design floating structures, it should be required to evaluate hydrodynamic motions and structural behavior under the wave loadings. Then, structural behavior of floating structures should be evaluated including the effects of wave-induced hydraulic pressure subjected to floating structures. However, there has been a problem to exactly evaluate structural behavior of floating structures since it was difficult to directly connect wave-induced hydraulic pressure resulting from hydrodynamic analysis with structural analysis model. In this study, in order to exactly evaluate structural behavior of floating structures under the wave loading, integrated analysis of hydrodynamic motion and structural behavior was carried out to the large-scaled floating structure. The wave-induced hydraulic pressure resulting from hydrodynamic analysis AQWA were directly mapped to structural analysis model ANSYS bia Workbench interface of ANSYS Inc.. As the results of this study, it was found that the integrated analysis of this study evaluate exactly structural behavior of floating structures under the wave loadings since this method can directly reflect wave-induced hydraulic pressure resulting from hydrodynamic analysis to structural analysis model. Also, as the results of structural behavior evaluation, it was found that the tensile stress on the top slab was maximized at the wave direction of $0^{\circ}$, and tensile stress on the bottom slab was maximized at the wave direction of $45^{\circ}$, respectively.