• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.533-538
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• 1993

본 논문에서는 퍼지제어 이론을 적용한 전지 유압 속도제어 시스템을 설계하였다, 최적의 퍼지 추론법을 유도하기 위해서 시뮬레이션 프로그램을 개발하여 최적의 샘플링 시간, A/D 및 D/A 변환기의 비트수를 결정하였고, 퍼지 입출력 변수의 형태, 퍼지 관계 행렬의 크기, 비퍼지화 방법 등을 시뮬레이션화하여 최적의 제어조건을 결정하였다, 전기유압 서어보 시스템에 적합한 퍼지 알고리즘은 Lsrsen 추론법, 비퍼지화 방법으로는 무게중심ㅂ버, 9*9 퍼지관계 행렬, 등간격의 삼각형 입출력 변수, 오차의 퍼지집합 및 오차 변화분의 퍼지집합이 각각 40과 5 일때 제어가 가장 잘 되었다. PID 제어방법과 비교할 때 퍼지제어가 우수한 성능을 보였으며,시스템의 등록성이 변할 때도 퍼지제어가 PID 제어 보다 적응이 잘 됨을 확인하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.1
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• pp.28-35
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• 2017

Recently, conventional hydraulic car lift systems face the technological limitations due to a lack of height control. The demand for height controllability is required in many tasks such as wheel alignment, and requires compensation for the structural deformation of the lift caused by irregular load distribution. In order to resolve this limitation of the conventional car lift, in this work, a new type of a hydraulic vehicle lift using a magneto-rheological (MR) valve system is proposed and analyzed. Firstly, the dynamic model of vehicle lift is formulated to evaluate control performance; subsequently, an MR valve is designed to obtain the desired pressure drop required in the car lift. Next, a proportional-integral-derivative (PID) controller is formulated to achieve accurate control of the lifting height and then computer simulations are undertaken to show accurate height control performances of the proposed new car lift system.

• Journal of the KSME
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• v.33 no.1
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• pp.22-32
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• 1993

본드선도는 물리적 등가가 적용되는 모든 상사 시스템을 대단히 조직이며 일관성 있게 모델링할 수있을 뿐만 아니라 시스템의 동적 방정식을 제어동역학 관점에 유리한 상태방정식으로 직접 유도할 수 있다. 또한 본드선도는 모델링 단계에서 무시된 각 요소들의 동적 특성 즉, 기계시스 템에서 회전축의 탄성처짐이나 운동 물체들 사이의 마찰 효과 전기 . 자기시스템에서 자속유출량, 그리고 유체 . 유압시스템에서 밀봉부분의 유량손실이나 압축성 유체 특성 등을 기곤에 구성된 본드선도의 변경 없이 각 특성들이 나타나는 본드상에 적절한 접합요소와 함께 단순히 첨가하여 고려할 수 있기 때문에 모델링 과정을 다시 반복하지 않고도 무시된 동적 특성들이 전체시스템에 미치는 영향을 파악할 수 있다. 특히 본드선도가 에너지 변환 장치나 에너지 유동 메카니즘이 복잡한 다에너지역 시스템 등에 거동이 전체시스템에 미치는 효과를 시각적으로 보다 세밀히 파악할 수 있을 뿐만 아니라 구성된 본드선도에 인과관계를 할당하여 본드선도의 접합요소를 통하여 유도된 최종적인 동적 방정식이 현실적으로 실현 가능한 물리시스템인지 파악할 수 있어 본드선도 모델링 단계에서 시스템을 묘사하는 동적 방정식의 옳고 그름을 평가할 수 있다. 이와 같이 본드선도는 기계, 전기 . 자기, 유체 . 유압, 열 시스템 및 이들이 조합된 복잡한 다에너지역 시스템 등을 효과적으로 모데링할 수 있는 매우 유용한 동적 시스템 모델링 방법이다.

• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.54-68
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• 2018

The objective of this study is to analyze the effect of dynamic characteristics of the check valve applied to the small piezoelectric-hydraulic pumps on flow rate formation. The flow rate of the piezoelectric-hydraulic pump is a key factor in the formation of the load pressure to operate the brake system. At this time, the natural frequency of the check valve operating in the fluid has a great influence on the formulation of the flow rate of the piezoelectric-hydraulic pump. In addition, the natural frequency of the check valve is affected by the gap between the check valve and the pump seat. In this study, the natural frequency of the check valve according to the gap between the check valve and the pump seat was calculated through the fluid-structure interaction analysis. The flow rate obtained from the simulation result was verified by comparing it with the result from the flow rate experiment using the developed piezoelectric-hydraulic pump.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.80-88
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• 2018

The function of a vehicle holding device (VHD) is to securely hold a launch vehicle on the launch pad and release the launch vehicle at maximum thrust after engine ignition to allow lift-off of the launch vehicle. During the release of the launch vehicle, to prevent the Ka doing a doing a doing mode, which is the vertical oscillation of the entire liquid propellant, the release of the launch vehicle should be gradual. In this study, for the gradual release of a launch vehicle, a hydraulic system comprising an accumulator and pyro valve to operate a hydraulic cylinder and control the speed of the cylinder with an orifice is introduced. Through a test, the influence of design variables on the cylinder speed is analyzed. Based on this, the design values of the hydraulic cylinder are determined. Through this study, the engineering basis for developing a VHD releasing a launch vehicle at maximum thrust is provided.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.68-78
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• 2023

In this paper, improvement measures were studied for false alarm (abnormal lighting) of emergency hydraulic warning light due to RF radiation signals in aircraft. When the warning lamp of the emergency hydraulic system is lit during flight due to electromagnetic interference caused by RF radiation signals, it affects flight mission and safety which can result in efficiency degradation and maintenance of flight mission. For false alarm of emergency hydraulic warning light, root cause analysis and troubleshooting were carried out. By shielding a composite strip under fuselage of the aircraft located in the path of the RF radiation signal, the RF radiation signal flowing into the emergency hydraulic indicator was blocked. Results of applying the improvement method through ground and flight monitoring were also described.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.1062-1070
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• 1995

The study deals with controlling the velocity of hydraulic motor with PI controller through the control of displacement pump which has higher efficiency than valve-controlled system. This was done as follows. First, we modified original displacement pump and designed this electrohydraulic puma system. Second, after experimenting static and dynamic characteristics, we identified system parameter of approximated model. Lastly, to control the velocity of hydraulic motor we controlled the angle of the swash plate of displacement pump. Test carried out in the laboratory shows that transient and steady state response could be improved by PI controller reducing power loss.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.2
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• pp.218-228
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• 2003

A hydraulic system is modeled as the second order differential equation with uncertain system parameters and disturbance composed of modeling errors. To Position the load of the hydraulic system to a desired point. the servo valve of the hydraulic system is controlled. As a control scheme. a global sliding mode control(GSMC) is Proposed Since the servo valve has a torque limit. the GSMC is designed to coordinate the position of the load along the minimum time trajectory within the torque limit. The Proposed control scheme can be designed with ranges of parametric uncertainties and specified torque limits. By the proposed control scheme, the closed form solution of the arriving time at the desired position can be estimated.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.2
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• pp.201-211
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• 2002

In this research, we are trying to research about hydraulic system design and vehicle dynamic modeling far the development of the tire roller. The reason why we would like develop it is that tire roller is one of the most useful machine for the road construction site and application other construction equipments. Here, we conceptualize the new hydraulic system and derive the equations of motion fur dynamic analysis and also investigate system modeling by using a DAQ board. We design the hydraulic circuit of steering and traction mechanism system. This design can be used to create virtual prototypes of construction equipment. So, we studied tire roller to integrate development technology. In system analysis, we formulate hydraulic traction system model and hydraulic steering system model. Also, we integrate DAQ system to acquire experimental results in real tire roller equipment.