• Journal of Drive and Control
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• v.18 no.1
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• pp.45-48
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• 2021

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.11
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• pp.963-970
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• 2015

In this study, the pressurization characteristics of the small piezoelectric hydraulic pump for a brake system has been analyzed through modeling the full hydraulic pump components; the pump chamber, check valve, pump load, pump drive controller etc. To analyze the pressurization characteristics, the process of charging pressure in the chamber with stacked-layer piezoelectric actuator were firstly modeled. Secondly, the flow coefficient of the check valve in terms of valve opening has been calculated after computational fluid dynamics analysis, such as the pressure distribution around check valve and the flow rate, was conducted. Also the pump driving controller, which controls the input voltage to the actuator, was designed to make the load pressure follow the input pressure command. The simulation results find that it takes about 0.03ms to reach the operating load pressure required for the braking system. The simulation result was also verified through comparison to the result of the pump performance test.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.404-408
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• 2013

In this Study, another way to accomplish the goal of meeting large steam-flow requirements is the use of multiple valves. Multiple valves can provide better control in meeting the precision pressure controller requirements. Simulation demonstrates the effectiveness of the pressure controller. The key point of this study is to precisely control the position of the control valve on the outside of the electro-hydraulic system using a special PID controller. Simulation and experiments verify the performance of the controller.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.05a
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• pp.79-82
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• 2006

본 논문은 원자력 발전소의 주요 제어계통 중에서 터빈 조속기 제어계통에 관련한 성능평가를 목적으로 한다. 터빈 조속기 계통은 고압의 유압계통으로 구성되어 있어 구동설비가 복잡하다. 복잡한 기계설비는 운전 중 많은 오동작에 의한 고장을 일으키고, 유지보수에 어려움이 있다. 이러한 복잡한 기계설비에 있어 운전원에 의한 기계성능 평가는 불리한 점이 많다. 예를 들어 서로 다른 시간에서 일어나는 같은 상황에 대해 다른 판단을 내릴 수 있다는 점이다. 터빈 조속기 계통의 기계설비에 있어서 터빈 밸브 유압공급 및 구동장치는 각 터빈벨브 자체에 부착되어 있어 터빈벨브를 동작시킨다. 터빈벨브들은 구동기 유압 서보실린더(Actuator Hydraulic Servo Cylinder)에 의해 열리고 압축된 스프링에 의해 닫힌다. 이러한 시스템을 진단하기 위해서 본 논문에서는 밸브의 내부 압력의 특징정보를 입력으로 하는 퍼지이론을 적용하여 터빈 밸브 구동설비의 성능을 판단하고자 한다. 퍼지이론에 적용하기위해 터빈 조속기 제어계통의 고압 터빈 조절 벨브와 고압 터빈 정지 밸브의 압력변화 데이터를 이용한다. 퍼지이론의 적용과정에서 퍼지 Rule은 실제 운전원이 압력변화 데이터에 대한 판단기준을 근거로 하여 정하기로 한다. 그리고 퍼지이론에 적용한 결과를 분석하고 실제 터빈 조속기 계통의 전문가가 판단 결과와 비교하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.1
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• pp.10-17
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• 2007

For the purpose of optimal control of anti-lock brake system, precise dynamic characteristics analysis of the hydraulic modulator, especially solenoid valve is necessary. However, most of researches so law have dealt with dynamic characteristic analysis of valve itself and the results have been restrictive to apply on the actual ABS modulator, where hydraulic pressure is acting. In this study, mathematical modeling and experimental analysis were executed in order to evaluate the valve dynamic characteristics when the hydraulic pressure applied. High pressure on the master cylinder effects on the valve dynamic characteristics have been analyzed quantitatively and performance improvement methods have been suggested varying the design factor. Consequently, results of solenoid valve dynamic characteristics analysis derived in the study can be utilized criteria for the optimal control of anti-lock brake system.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.4
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• pp.1-8
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• 2010

본 논문은 유압해석 상용툴인 AMESim을 이용하여 로드센싱형 휠로더 유압 시스템을 모델링 하였다. 휠로더 유압장치의 주요 구성요소인 펌프, 메인 컨트롤밸브, 압력 보상기, 리모트 컨트롤밸브 및 작업 장치를 모델링 하였으며 실제 차량의 제원을 적용하여 시뮬레이션을 수행하였다. 시뮬레이션 결과와 실차 데이터를 비교 검토하여 시뮬레이션 결과와 실차 데이터가 유사함을 알 수 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.3
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• pp.231-237
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• 2007

The torque ripple of the hydraulic pumps for the Electro-hydrostatic Actuators can disturb the cylinder position control under slewing speed operation condition. In principle, the periodic change of the reaction torque generated by a piston type pump is highly dependent on the waveform of its cylinder chamber pressure. In case of uni-directional pumps operating at constant speed, the transient overshoot and rising slope of the cylinder pressure can be adjusted by the precompression angle and notch shape of their valve plates. Therefore, the influence of the valve plate geometry on the torque ripple magnitude of a bent-axis type piston pump for EHA application was investigated in this study. The results showed that any improvement of the torque ripple of such a bi-directional pump can not be achieved by modifying the valve plate geometry, regardless of its operation speed.

• Journal of Aerospace System Engineering
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• v.12 no.2
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• pp.7-14
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• 2018

In this study, a new check valve was studied to improve the load pressure of a brake system with a small piezoelectric-hydraulic pump. During the pressurization process, the steady-state pressure at the load is affected by the ratio of the cross-sectional area of the check valve the chamber pressure and load pressure. Since the flow path cover of the check valve is made wider than the cross-sectional area of the output flow to prevent backflow, a method of reducing the area ratio is proposed for a higher load pressure by mounting an additional mass to a thin plate spring type check valve. To identify the effect of mounting an additional mass to the existing check valve on the load pressure, a simple brake system with a small piezoelectric-hydraulic pump was modeled using a commercial code AMESim. The AMESim modeling was verified by comparing the simulation results with the experimental results of the pump the existing check valve. The additional mass was added to the verified AMESim modeling and higher load pressure was able to be obtained through simulation. The 35% performance improvement in load pressure identified by carrying out pressurization test of the brake system after adopting the new check valve the small piezoelectric-hydraulic pump.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.4
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• pp.121-130
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• 2001

For the purpose of optimal control of anti-lock brake systems, precise dynamic characteristics analysis of hydraulic modulator, especially solenoid valve is necessary. However, most of researches so far have dealt with dynamic characteristic analysis of valve itself, and the results have been restrictively applied to the actual ABS modulator, where hydraulic pressure is acting. In this study, mathmatical modeling and experimental analysis were peformed in order to evaluate the valve dynamic characteristics when the hydraulic pressure is applied. High pressure on the master cylinder that affects on the valve dynamic characteristics have been analyzed quantitatively, and performance improvement methods have been suggested through parameter study. Consequently, results of solenoid valve dynamic characteristics analysis derived in the study can be utilized as criteria for the optimal control of anti-lock brake systems.

• Journal of the KSME
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• v.18 no.2
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• pp.118-121
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• 1978

지난번 강좌에서는 유압밸브의 스푸울에 작용하는 반경방향의 유동력(Iateral flow force)에 대해 서 그 원인과 대책을 소개하였다(대한기계학회지 vol.2, No.1).여기서는 스푸울에 작용하는 축방향 의 유동력(axial flow force)을 기술하는 방법과 이에 대한 보상방법(method of compensation)을 소개한다. 축방향의 유동력은 유체의 운동방정식을 적분형으로 고쳐 쓴, 소위 운동량 이론을 적용 함으로써 그 표현을 용이하게 얻을 수 있다. 그러므로 먼저 유동력의 보석에 적용될 수 있는 운 동량 이론을 소개하고, 스푸울의 형상이 비교적 간단한 경우에 대해서 유동력을 계산하고, 그 보상방법을 논의한다.