• 한국기계가공학회지
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• 제2권3호
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• pp.41-47
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• 2003

In this study an elevator plant model is made with an electro-hydraulic servo valve and a single rod cylinder. A PID controller, a velocity feedback PID controller and a MRAC controller ate designed. Experimental apparatus including an elevator plant model and these controllers are constructed. In case of experiment, external load which is made with a hydraulic cylinder and a pressure control valve burdens varying load to the elevator plant model being driven. With experiment, the control performances of three proposed control methods are compared.

• 한국정밀공학회지
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• 제28권8호
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• pp.936-941
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• 2011

This paper deals with the issue of motion control of a single rod cylinder-load system using simple adaptive control (SAC) method. Prior to controller design, the experiment of open-loop response has been performed. Based on it, design parameters of transfer function are obtained and used for controller design. The effect of parallel feedforward compensator has been investigated by computer simulation, suppressing the oscillatory motion. Through experiments it is conformed that the SAC method gives good tracking performance compared to the PD control method.

• 한국정밀공학회지
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• 제20권12호
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• pp.89-95
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• 2003

A PID controller integrated with a velocity feedback is designed for fluid power elevator model system in this study. In this case, for outside disturbance load a hydraulic cylinder and a pressure control valve are used. In this method overshoot is reduced and settling time becomes also shorter than the values achieved from the PID controller system only In conclusion a PID controller integrated with a velocity feedback is considered a suitable control method for fluid power elevator system.

• 플랜트 저널
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• 제6권4호
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• pp.63-71
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• 2010

The best way to prevent the corrosion of piston rod is a selection of quality of the material and method of construction which minimize the porosity. The high velocity oxy fuel(HVOF) method, which generates lower porosity than existing plasma spray, was applied to ceramic laminated bond layer. Porosity percentage fell to bellow 2%, lower than that of plasma spray at 7%. Coating material of ceramic-coated main layer was selected as the $Cr_2O_3$ affiliation material, which is more dense than $Al_2O_3$ affiliation. To fill up the pores formed after the coating process, we sealed the bond layer and main layer. Sealing process was performed twice, once after the coating and once after the grinding. Upon the anti-corrosion test on the sealed sample and on the non-sealed sample, it is confirmed that the sealed sample was not corroded for 1,000 hours while the non-sealed sample was corroded within 48 hours.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.199-204
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• 2000

A cylindrical brake device with plastic deformation is designed to stop the object moving at high velocity. Baseline model is determined based on the design specification and analytic solutions. Using finite element method, effects of various design parameters, such as thickness of the cylinder, clearance between cylinder and rod, and cone angle, to the performance of the brake device are investigated. Cone-type brake device shows better performance than cylindrical brake device with constant thickness in that plastic hinges are generated sequentially from impact end to fixed boundary, thus increasing the reliability of braking operation.

• Journal of Advanced Marine Engineering and Technology
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• 제41권1호
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• pp.118-124
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• 2017

본 연구대상 디젤기관의 연접봉 볼트, 크랭크 핀 베어링 볼트 등의 손상원인을 조사 분석하기 위하여 수행한 현장검사, 파손부에 대한 시험 및 고찰, 참고문헌 및 연구자의 경험 등을 통하여 다음과 같은 결론을 얻었다. 파손된 크랭크 핀 베어링 볼트는 연접봉 볼트보다 늦게 파손된 것으로 추정된다. 파손된 연접봉 볼트는 충격적인 하중에 의해서 취성파괴된 것이 아니고, 비정상적인 반복하중(예를 들어 체결 볼트의 풀림 등)에 의해서 피로파괴가 되었다는 것을 그 파단면의 모습을 통하여 알 수 있다. 파손된 연접봉 볼트용 U 너트는 윤활유(고착방지제)의 부적절한 사용, 각 실린더와 연접봉 별로 구분되어 사용되지 않았던 것 등으로 인하여 표면 상태가 불량하게 되었고, 이것은 연접봉 볼트의 파손사고에 영향을 미쳤을 가능성이 있다고 할 수 있다. 그리고 파손된 국내 제작품인 연접봉 볼트와 크랭크 핀 베어링 볼트의 기계적 성질, 전조공정 등은 해당 볼트의 설계요건에 적합하다고 할 수 있다.

• 대한기계학회논문집B
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• 제26권5호
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• pp.675-684
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• 2002

Two-dimensional, angle-resolved LDV(Laser Doppler Velocimetry) measurements of the turbulent rotating flow field in a confined cylinder have been performed. The configurations of interest are flows between a rotating upper disk with a rod attached by a disk or impeller($\theta$ = 45$^{\circ}$, 90$^{\circ}$) and a stationary lower disk in a confined cylinder. The mean flow velocity as well as the turbulent intensity of the flow field have been measured. The results show that the flow is strongly dependent on the position of the impellers or the disk, negligibly affected by the Reynolds number in turbulent flow. It is observed that the mixing effect of the axial flow impeller($\theta$ = 45$^{\circ}$) is better than that of the radial flow impeller($\theta$ = 90$^{\circ}$) or a disk.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1018-1025
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• 2003

The diesel engine is often a serious excitation source in ships. Both the varying cylinder gas forces and the reciprocating and rotating mass forces associated with the crank and the connecting rod mechanism produce ample possibilities for excitation of the engine structure itself, the shafting, the surrounding substructures as well as the hull girder. This paper presents a guide for optimization of excitation forces produced by the marine propulsion 2-stroke diesel engine. The computational program for predicting the excitation forces is developed and applied to 2-stroke in-line engines. The object function is defined as the work done by every cylinder excitation force which is related to the mode shape of the diesel engine system, especially in the torsional vibration of the shafting. As a practical application of the presented method, the crank angle of 7 cylinder 2-stroke engine is optimized to reduce torsional vibration stresses on the shafting. Compared with the regular firing angle, about 60% of the 4th order torsional vibratory stress on the propeller shaft can be reduced by optimizing the crank angle irregularly. The usefulness of the presented optimization method is confirmed by the measurements.

• 한국소음진동공학회논문집
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• 제14권8호
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• pp.709-717
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• 2004

The diesel engine is often a serious excitation source in ships. Both the varying cylinder gas forces and the reciprocating and rotating mass forces associated with the crank and the connecting rod mechanism produce ample possibilities for excitation of the engine structure itself, the shafting, the surrounding substructures as well as the hull girder. This paper presents a guide for optimization of excitation forces produced by the marine propulsion 2-stroke diesel engine. The computational program for predicting the excitation forces is developed and applied to 2-stroke in-line engines. The object function is defined as the work done by every cylinder excitation force which is related to the mode shape of the diesel engine system, especially in the torsional vibration of the shafting. As a practical application of the presented method. the crank angle of 7 cylinder 2-stroke engine is optimized to reduce torsional vibration stresses on the shafting. Compared with the regular firing angle, about 60 ％ of the 4th order torsional vibratory stress on the propeller shaft can be reduced by optimizing the crank angle irregularly. The usefulness of the presented optimization method is confirmed by the measurements.

• 항공우주시스템공학회지
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• 제8권2호
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• pp.7-13
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• 2014

In order to enable fail-safe operation the electro-hydrostatic actuators can be dualized. When a symmetrical actuator is combined in series with an asymmetrical actuator with single rod cylinder, the flow rates of their cylinders are unmatched. If their position controller has same configuration, one of their pumps can supply too much flow rate under particular load conditions, which should be bypassed into low pressure side e.g. by a relief valve. In this paper it is shown how the hydraulic circuit for the asymmetrically combined electro-hydrostatic actuator can be designed without sacrificing power consumption.