• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.20-26
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• 2011

This paper is to investigate noise source for reciprocating type air compressors. The reciprocating type air compressors are widely used in the small and medium sized enterprise and many employees are affected and irritated by their noise during working. The investigation and analysis of the noise source were made according to the ISO 1680/1 and MIL-STD 7410-1 and noise evaluation of each part of compressors was made. Noise emitted from the intake and exhaust valve and the air receiver tank were dominant compared with those from other parts of compressor. Noise from the motor and the revolution of crank mechanism was negligible relatively with the noise sources as mentioned above.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.99.2-99.2
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• 2005

• Journal of Drive and Control
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• v.18 no.2
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• pp.1-8
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• 2021

In this work, a circuit with a hydraulic power unit is formulated as a means of predicting the behavior of the prefill valve in the future. The behavior of the prefill valve can be examined by the measurements of the configured power unit, and the performance is determined by using hydraulic pumps, relief valves, and hydraulic hoses that make up the power unit. In particular, pressure/flow pulsation generated by hydraulic pumps can cause instability in the prefill valve and cause noise-induced degradation of the overall performance and reliability of the hydraulic system containing the prefill valve. Therefore, to study the behavior and performance of the prefill valve in a relatively accurate manner, the prediction of the characteristics of the hydraulic power unit driving the prefill valve is very important. In this study, the pulsation characteristics of the hydraulic pump were analyzed to theoretically demonstrate its relationship with different settings of the power unit, such as relief valve pressure settings and the presence/absence of the hose.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1087-1094
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• 2003

The piston slap phenomenon occurs when the piston collides with the internal wall of the cylinder. Impact force caused by piston slap is one of the major mechanical noise sources in reciprocating compressors. In response to public demand, strict regulations are increasingly being imposed on the allowable noise level which is caused mostly by household electric appliances. In this paper, forces acting on piston by considering the dynamic behavior of suction and discharge valves are analytically calculated and the piston slap caused by the piston secondary motion is investigated by the finite element method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.2
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• pp.35-43
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• 1999

The paper describes an approach for measuring delivery flow ripple generated by oil hydraulic axial piston pumps. In order to reduce pressure ripple which cause to undesirable noise. vibration and fatigue in hydraulic systems it is indispensible measure a delivery flow ripple from pumps. Since the flow ripple measurement of flow pumps is independent of the dynamic characteristics of the connected hydraulic circuit the measurement of flow ripple is most suitable for pump fluid-borne noise rating. The measurement of flow ripple with high frequencies from axial piston pumps is made by applying the remote instantaneous flow rate measurement method which is based on the dynamic characteristics between pressure and flow rate in hydraulic pipeline. The measured flow ripple waveforms are influenced by the configuration of V-shaped triangular relief groove in the valve plate. It can be seen that the appropriate relief groove in valve plate reduces the pressure and flow ripple amplitude and frequency spectrum for high harmonics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1125-1130
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• 2007

This paper presents a maneuver analysis of a full-vehicle featuring electrorheological (ER) suspension and ER brake. In order to achieve this goal, an ER damper and an ER valve pressure modulator are devised to construct ER suspension and ER brake systems, respectively. After formulating the governing equations of the ER damper and ER valve pressure modulator, they are designed and manufactured for a middle-sized passenger vehicle, and their field-dependent characteristics are experimentally evaluated. The governing equation of motion for the full-vehicle is then established and integrated with the governing equations of the ER suspension and ER brake. Subsequently, a sky-hook controller for the ER suspension and a sliding mode controller for the ER brake are formulated and implemented. Control performances such as vertical displacement and braking distance of vehicle are evaluated under various driving conditions through computer simulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.215-215
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• 2014

현재 가장 많이 사용되고 있는 스프링식 안전밸브는 스프링과 설정치 드리프트, 누설 취약성, 채터링에 의한 시트 파손등의 문제점을 지니고 있다. 안전밸브 디스크에서 발생하는 유체 누설은 안전밸브 설정압력 개방에 영향을 주며, 시트(Seat)면의 이물질 삽입, 균열 및 유체에 의한 침식(Erosion) 등에 의해 밸브 핵심 부품이 쉽게 손상되어 기기 성능 저하를 초래하게 된다. 따라서 유체 누설을 조기에 탐지하고 정량화하여 해당 기기의 상태정보 제공을 통한 누설 감지 기법 연구가 요구된다. 원자력 발전소의 경우 밸브에서 유체가 누설되면 밸브의 오작동 및 운전 안정성 저해 요인이 된다. 따라서 본 연구에서는 음향방출법을 이용하여 안전밸브의 유체 누설을 평가하고, 안전밸브의 음향신호 측정 위치 선정 및 누설량에 따른 음향신호를 분석하고자 한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.171-176
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• 2008

Active suspension controls stiffness and damping between unsprung mass and sprung mass in order to increase the ride quality. However, to increase the riding quality, the handling quality should be decreased and the rattle space should be increased. So, active suspension should cope with these conflict conditions. Therefore its actuating devices have to produce sufficient actuating force and have sufficiently short response time. In this paper, the dynamic characteristics of 1/4 car model with an active suspension is studied according to hydraulic design variables. The active suspension consists of a hydraulic servo valve and a hydraulic cylinder. It shows better performance when it has more powerful and faster actuator.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2071-2075
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• 2003

Pressure variation is one of the major sources on noise emission in the oil hydraulic piston pumps. Therefore, it is necessary to clarify about pressure variation characteristics of the oil hydraulic piston pumps to reduce noise. Pressure variations in a cylinder at trapping region were measured during pump working period with discharge pressures, rotational speeds. The effect of pre-compression of the discharge port with three types valve plates also investigated. It was found that the pressure variation characteristics of oil hydraulic piston pumps deeply related with pre-compression design of the discharge port. Also, it was found that the pressure overshoot at trapping region can reduce by use of pre-compression at the end of the discharge port in valve plate

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.420-424
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• 2008

The new MOV(motor-operated valve) diagnostic system MOVIDS(MOV intelligent diagnostic system) was developed. Its remote diagnostic methods with high accuracy have improved the applicability. This enables the diagnostic tests and the evaluations of many MOVs not only at the valves but also in remote places like MCCs(motor control centers). The remote diagnostic ability of the new system reduces the cost and the man power for diagnosing MOVs and eliminates the danger of the toxic or radioactive environments to which workers might be exposed.