• 동력기계공학회지
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• 제11권1호
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• pp.39-44
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• 2007

The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve(main steam dump valve) and check valve(main steam outlet pump check valve) on the normal size of 12 and 18". The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.

• 한국정밀공학회지
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• 제16권12호
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• pp.31-39
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• 1999

Previous researches and experiments have already verified that the primary noise source of high pressure tandem axial thpe piston pump is fluid-borne noise from the process of oil distribution between the kidney-shaped port and valve plate. So, many researchers have improved pressure gradients and reduced sound levels by applying pre-compression and pre-decompression metering grooves to valve plate. In practice however, the sound level of th high pressure tandem axial type piston pump is still undesirable. This paper testified the effect of pumping phase of the piston on vibration and noise of th high pressure tandem axial type piston pump on the best of theoretical research in $this^(1)$. Therefore considering the pumping phase of the piston when assembling the tandem axial type piston pump, it is possible to reduce 1.5~2[dB]of sound level.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.694-699
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• 2004

The purpose of this study is to estimate the availability of acoustic emission method to the internal leak of the valves at nuclear power plants. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. From the comparison of the background noise data with the experimental results as to relation between leak flow and acoustic signal, the minimum leak flow rates that can be detected by acoustic signal was suggested. When the background levels are higher than the acoustic signal, the method described below was considered that the analysis the remainder among the background noise frequency spectrum and the acoustic signal spectrum become a very useful leak detection method. A few experimental examples of the spectrum analysis that varied the background noise characteristic were given.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.756-757
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• 2011

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.480-485
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• 2009

This paper presents dynamic modeling and control analysis of a military vehicle suspension featuring MR valve structure. Firstly, the dynamic model of the suspension system which is included gas spring, MR valve and gas chamber is established with respect to the disturbance. Secondly, the friction model of the suspension system is derived by considering experiment result of the MR suspension system. And then, response characteristics of the damping force with respect to the magnetic field and friction force with the proposed friction model are provided to show the feasibility of practical application. In addition, control performance of the proposed MR suspension system is evaluated with quarter vehicle.

• 한국소음진동공학회논문집
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• 제20권1호
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• pp.58-65
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• 2010

This paper presents dynamic modeling and control analysis of a military vehicle suspension featuring MR valve structure. Firstly, the dynamic model of the suspension system which is included gas spring, MR valve and gas chamber is established with respect to the disturbance. Secondly, the friction model of the suspension system is derived by considering experiment result of the MR suspension system. And then, response characteristics of the damping force with respect to the magnetic field and friction force with the proposed friction model are provided to show the feasibility of practical application. In addition, control performance of the proposed MR suspension system is evaluated with quarter vehicle.

• 한국자동차공학회논문집
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• 제9권1호
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• pp.37-44
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• 2001

This study is focused on the development of a new muffler. A control valve installed in the exhaust system is operated by torsion springs, and its open angle is controlled automatically corresponding to the engine operating conditions. The experiments were done using an exhaust system simulator having the same pulsation wave frequency and similar pulsation propagation characteristics of a real exhaust system. The purpose of this study is to develop a new muffler system which has improved noise reduction quality and less power loss than conventional mufflers and electronic-control mufflers.

• 소음진동
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• 제9권4호
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• pp.754-760
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• 1999

The valve motions of a reciprocating compressor generate the pressure fluctuation at the plenum which is a main source of noise and vibration of a compressor unit. But a cycle of a compressor process consists of complicated phenomena interacting in a short period of time. A mathematical model is developed by simplifying and idealizing the complicated phenomena to simulate the compressor process. The governing equations about the pressure and working fluid flow are developed from the unsteady Bernoulli equation. The pressure fluctuations at the plenums are derived from the Helmholz's resonator model. The valves are modeled as one degree of freedom spring-mass-damper system. This model is verified by the experimental results.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.329-334
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• 2003

Design of pre-compression region(trapping region) of the valve plate is an important element to minimize the pressure fluctuation in a cylinder and in discharge process, and pump noise. In this study, we tried to prove what the characteristics of the oil hydraulic pump would be according to the angle of the trapping region. Three kinds of asymmetrical valve plates were used. As a result, we found that by designing the trapping region, the slope of the pressure rise in the cylinder port from low-pressure suction region to high-pressure discharge region is relaxed and the pressure fluctuation width and the discharge pressure pulsation are reduced. Therefore, because the pump gets smooth pressure fluctuation and low fluid Impact, the pump noise is reduce.

• 한국소음진동공학회논문집
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• 제22권11호
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• pp.1049-1056
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• 2012

The forced vibration response characteristics of a cracked pipe conveying fluid with a concentrated mass are investigated in this paper. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Hamilton's principle. The effects of concentrated mass and fluid velocity on the forced vibration characteristics of a cracked pipe conveying fluid are studied. The deflection response is the mid-span deflection of a cracked pipe conveying fluid. As fluid velocity and crack depth are increased, the resonance frequency of the system is decreased. This study will contribute to the decision of optimum fluid velocity and crack detection for the valve-pipe systems.