• Journal of the Korean Society of Industry Convergence
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• v.4 no.3
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• pp.305-310
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• 2001

Hydraulic power shifting systems of hydraulic travel motor may be far safer than mechanical power transmission systems. Thus, hydraulic power shifting systems are widely used for speed control on the hydraulic equipments. In the case of liquid shifting lines, the rapid change of area, such as valve closing, can result in a large pressure transient. It is necessary to assure proper control method in order to obtain the smallest shift shock. This study conducts the shock characteristics of hydraulic power shifting system of the hydraulic travel motor. Experimental results show that shock pressure depends on the operating pressure, flow rate and pipe line area. The shock characteristics can be applied for reducing shocks.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.33-36
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• 2010

The attention in construction Automation is getting higher since it could be the answer to the lack of skilled labor by decrease in construction population and aging which adversely affects productivity and quality in the construction site. We are on the way to develop a construction automation system adequate for domestic circumstances in Korea; it is called RCA(Robotic-crane based Construction Automation)system. Climbing hydraulic robots system is a part of RCA system and makes Construction factory(CF) climb through the guide rail on the core wall. The safety of climbing hydraulic robots system is at issue due to the overloaded weight of CF. Preventing this issue, present study did the design verification through the structural analysis and the simulation. Mock-up test also was done to analyze the drive performance of climbing hydraulic robots system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1008-1013
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• 2012

Electro-hydraulic power steering (EHPS) system is the power-assisted steering which operates the hydraulic pump by BLDC motors for assisting the steering force. EHPS consists of BLDC motor, gear pump, oil-hydraulic circuit and steering system. Since EHPS is a convergence system consisting of electricity and electronic, hydraulic and mechanical system, it is difficult to establish the simulation model. In this paper, the mathematical model of EHPS system components were presented, and the simulations of the multi-domain system were performed by using AMESim. The trial and error of development would be reduced by using this simulation results, and it would be helpful for developing high-quality EHPS.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.498-505
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• 2000

Performance of a hydraulic system is influenced by its working temperature. Therefore, it is very important to make the system perform uniformly in an entire range of the working temperature. In this study a simulation of a hydraulic control system for the powershift transmission of tractors was conducted and the effect of the temperature was investigated in terms of design conditions of the system. Results of the simulation are as follows. The hydraulic control system with a spring accumulator was found to be more convenient to control the shifting time than that with a gas accumulator. By returning the oil from the clutches to the system through a path between the filter and pump, the time delay due to the pressure difference between the low and high temperatures could be reduced. Therefore, it was recommended that the hydraulic control system for the powershift transmission of tractors must be equipped with a spring accumulator and a circuit to return oil from the clutches to the system through a path between the filter and pump.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1109-1114
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• 2007

This paper presents the road simulator control technology for reproducing the road input signal to implement the real road data. The simulator consists of the hydraulic pump, servo valve, hydraulic actuator and its control equipment. The QFT is utilized to control the simulator effectively. The control system illustrates a tracking performance of the closed-loop controller with low order transfer function G(s) and pre-filter F(s) for a parametric uncertain model. A force controller is designed to communicate the control signal between simulator and digital controller. The efficacy of the QFT force controller is verified through the numerical simulation, in which combined dynamics and actuation of the hydraulic servo system are tested. The simulation results show that the proposed control technique works well under uncertain hydraulic plant system. The conventional software (Labview) is used to make up for the real controller in the real-time basis, and the experimental works show that the proposed algorithm works well for a single road simulator.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.148-154
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• 2000

In this study, the static and the dynamic characteristics of the load-sensitive hydraulic pump control systems of a hydraulic excavator were analyzed using the developed analysis tool. The results were compared with the experimental ones. To improve the static performance of the system, the system parameter effects on the controllable region and the pump pressure variation were studied. The parameters enhancing dynamic characteristics were also considered.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.68.2-68
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• 2001

A position control system using hydraulic cylinder is modeled as a nonlinear system. In order to control this nonlinear system, in this paper, the fuzzy PID control technique which has time-varying control parameters is adopted. In this study, an exclusive sensor to detect the position of hydraulic cylinder is used, which is embeded in hydraulic cylinder.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.332-337
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• 1988

A digital series-feedback compensator algorithm for tracking time-varying signal is presented. The series-feedback compensator is composed of one closed loop pole / zero cancellation compensator and one desired-input generator. This algorithm is applied to nonlinear hydraulic position control system. The hydraulic servo system is modelled as a second order linear model and cancellation compensator is modelled from it. The desired input generator is inserted to reduce modelling error. Digital computer simulation output using this control method is present and the usefulness of this control algorithm for nonlinear hydraulic system is verified.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.675-680
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• 1990

According to the recent increase of demands for multi-function and economics on hydraulic excavator, it is required that excavator should have simple operation, higher and operational efficiency. However, it is difficulty for current hydraulic system to satisfy demands fully. This study shows that new control system improves power transmission efficiency, work capability of engine and hydraulic system of current excavator.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.2
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• pp.124-130
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• 2003

The electro-hydraulic servo system with a servo valve is applied widely in force control. However, the composition of control system using a servo valve is difficult due to nonlinearities in the servo valve, such as square-root terms in flow equation. The electro-hydraulic servo system using a DDV(Direct Drive Valve) instead of a servo valve was proposed and it's characteristics was estimated. The DDV and whole system are modelled by parameter identification using the input-and-output data, then the models are verified by the comparison of simulation with experiment. Also, the state feedback controller has been designed based on this model, then the performance of the electro-hydraulic force servo system using a DDV is evaluated by simulation and experimental results.