• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.80-88
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• 2010

In a conventional system, hydraulic unit pumps out pressurized oil when the power use is not even necessary. As a result, it causes much power loss. This study is on the proposal of new hydraulic unit which controls the revolution of the pump in order to produce proper power needed and to have good response characteristic. In addition, the existing control methods such as PID control method, fuzzy control method, and adaptive control method are applied to the proposed hydraulic unit. Then the best control method is selected and the controller is developed to realize minimum power loss.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.177-181
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• 1992

For this study, a new hydraulic control unit which designed in compact compared to the currently manufactured hydraulic control unit for ABS has been introduced and its experimental model has been made. Based on the basic principle as ABS using braking force characteristics against slip ratio of tire, half car model bench tester were designed and made to make an analysis of braking effect of the new hydraulic control unit. Experiment for slip ratio characteristics of tire has been carried out using half car model bench tester and with the results of this experiment and control experiment of the new hyraulic control unit, the experiment result of the characteristics of tire and control experiment were compared to find out their correspondence. And furthermore, slip ratio characteristics of the new hydraulic control unit has been studied based on the experiment result of slip ratio characteristics of tire through simulation and compared with experiment result.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1249-1255
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• 2010

An ultra high- pressure system generally consists of a hydraulic power unit, an oil supply unit, an electrical power supply device, and an electrical control device. The hydraulic power unit supplies the hydraulic power to the intensifier to create generate ultra high pressure. The intensifier amplifies increases the pressure using the oil supplied from by the hydraulic power unit. The electrical supply devices and control devices maintain are provided for the electric motors, valves, and sensors. In this study, instead of a flow-control device, a pressure-control type device was mounted on a manifold block in the hydraulic power unit instead of the flow-control type. A servo valve was fitted in the intensifier, and the performance characteristics of the intensifier varied according to the variations of in the pressure cycle and with the temperature of the operating oil in the hydraulic power unit.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.733-738
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• 2004

This paper deals with feedback control of a hydraulic unit for direct yaw moment control, a method used to actively maintain the dynamic stability of an automobile. The uncertain parameters and complex structure naturally call for empirical modeling of the hydraulic unit, which readily results in a control-oriented model with high fidelity. The identified model is cross-validated against experimental data under various conditions, which helps to establish model uncertainty. Then, the $H_{\infty}$ optimization technique is employed to synthesize a controller with guaranteed robust stability and performance against the model uncertainty. The performance of the synthesized controller is verified using experimental results, which shows the viability of the proposed approach in a real-world application.

• Proceedings of the KIEE Conference
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• summer
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• pp.1355-1357
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• 2004

The hydraulic brake system is recently apply to the AGT system such merit as installation is convenient and brake force is stronger than pneumatic brake system. The hydraulic brake system consist of brake operating unit, electronic control unit, air compressor and pneumatic/hydraulic tranducer. The components of it are controlled and designed to perform the function of brake system. Therefore, This paper design and the hydraulic brake system and propose the derection of development for Urban Transit System.

• Journal of Biosystems Engineering
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• v.23 no.5
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• pp.427-438
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• 1998

In Korea, rotary implements are mainly utilized in the tillage operation. The attitude control system for rolling phenominon of tractors, which in caused due to uneven ground surfaces and sinkage of tractor wheels, is one of the most important control systems in agricultural tractors. The attitude control system of a rotary implement, attached on tractors, was designed and fabricated in this study. The control system was largely composed of four main units; a setting unit, a detection unit, a controller and a hydraulic unit. The implement was controlled by control signals from a computer proportional to controlled errors, on/off action of two directional solenoide valve and lift cylinder on the right lift rod. Response characteristic experiments for the control system fabricated in this study were carried out indoors and outdoors. The results of experiments showed the response characteristics sufficient to use as the attitude control system of rotary implements for agricultural tractors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2106-2112
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• 2013

In a traditional hydraulic elevator, elevator car is descended by down control valve, and the oil hydraulic energy must be lost during the descending stroke. In this paper, hybrid type energy saving unit for a hydraulic elevator is researched to save the hydraulic energy which is lost during the descending stroke. The energy is stored as converted electrical energy, and the saved energy is reused as the auxiliary power for the ascending stroke of elevator car or the main power of other parts. The results show that the output characteristics are stable and good and the research is successful and useful to reuse the saved energy during the descending stroke of elevator car.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.897-902
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• 2004

The hydraulic brake system is recently apply to the AGT system such merit as installation is convenient and brake force is stronger than pneumatic brake system. The hydraulic brake system consist of brake operating unit, electronic control unit, air compressor and pneumatic/hydraulic tranducer. The components of it are controlled and designed to perform the function of brake system. Therefore, This paper design and the hydraulic brake system and propose the derection of development for Urban Transit System.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.259-261
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• 2005

The hydraulic brake system is recently apply to the AGT system such merit as installation is convenient and brake force is stronger than pneumatic brake system. The hydraulic brake system consist of brake operating unit, electronic control unit, air compressor and pneumatic/hydraulic tranducer. The components of it are controlled and designed to perform the function of brake system. Therefore, This paper design and the hydraulic brake system and propose the detection of development for Urban Transit System.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.94-102
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• 1995

The active control system of structural vibration using a hydraulic actuator is developed. The developed system consists of three parts : a hydraulic unit, an actuator unit and a control unit. Structural vibration is sensored by the accelerometer attached to the structure and reduced by the optimally controlled motion of active mass giving anti-phase inertia force to the structure. It is experimentally confirmed that the vibration level of model structure is reduced to about 1/6 by the developed active control system.