• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.272-273
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• 2012

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.270-271
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• 2012

• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.27-32
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• 2004

Recently, the expansion of social infrastructures and urban redevelopment, the construction works have been a rapidly increase. The subway's noise and vibration are on a continuously increasing status in its importance as by the industrial and cultural development process. Nevertheless, in our country, adequate alternative idea for the construction noise and vibration are not yet established. In this point, the purpose of this study is to know the vibration effect to the structure. This study was used to determine the standard of vibration and the way of losing vibration. The case of construction site is a good example. The data of this study was obtained by a construction company in Korea. Vibration effect could cause structural problems and affect human mental state. The results of this study are as follows; check the vibrating point, determine the suitable limit of vibration, make a good plan and construction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.10
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• pp.902-908
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• 2013

The input torque ripple induced by combustion engines is a significant source of NVH(noise, vibration and harshness) problem in automotive transmissions. Because this torque fluctuation is primarily transmitted to the input shaft of automotive powertrains(e.g., automatic transmissions) when the lock-up clutches are closed, a torsional damper with helical springs is generally inserted between engine and transmissions to isolate the input vibratory energy, which is essential for the passenger comfort. The torsional vibration isolator exhibits frequency ranges in which there is low vibration transmissibility. However, the isolation performance is currently evaluated through the static torsional spring characteristics. In this study, the transmissibility of torsional spring dampers, essential dynamic performance index for vibration isolator, is first experimentally evaluated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.8
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• pp.331-337
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• 2001

The purpose of this study is to analyze the principal causes of vibration problem and find out the method of vibration reduction in a chip-mount system. The principal causes are investigated through measurements of vibration spectrum and model parameters. Modal parameters are obtained by using an experimental model test. Based on the model parameters from experiments. a model of finite element method is formulated. The model presents effective redesign of increasing the natural frequencies in order to reduce the vibration of a chip-mount system. Further, through computer simulation for the behavior of head to be main vibration source, the best acceleration pattern of head movement can be verified to achieve effective head-positioning and reduce the vibration due to head movement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.29-33
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• 1996

This paper addresses a systematic way of understanding the transfer characteristics of whole-body vibration due to the external excitation. Amirouche's and Tamaoki's models are considered, whose analysis shows a new result that resonant frequencies related to the head vibration are well coincided with those of the body. This point reveals that the improvement of the ride quality of passenger cars can be achieved by isolating only external vibration components transfered to the body. Finally, this paper points out the limitation of previous whole-body vibration models, which gives the motivations of setting up more 'practical and generalized' whole-body vibration models of interests in this study.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.738-742
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• 2005

Ground vibration at Gil-dong in Seoul induced by the 5th ling of Seoul Subway is predicted using various prediction methods and compared with measured vibration. Also, several issues on the improvement of prediction methods are discussed. Furthermore, as an alternative vibration source, measured vibration acceleration level(VAL) on the tunnel wall of the Bundang line of Seoul Subway is applied to the prediction of the VAL at the location mentioned previously. Then requirements accompanied to the suggestion of the new vibration source appropriate to the condition of Seoul Subway.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.3
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• pp.186-193
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• 2003

Floor vibrations in residence and office buildings are typically induced by heel drop and walking movement of occupants. The criteria of most vibration provisions have been developed based on the vibration caused by heel drop impact rather than walking. There may be considerable differences between the vibration characteristics induced by walking and heel drop. The effect of walking vibration was not well reflected on current provisions. In this paper, shaking table test was performed to investigate the human perception level against the vibrations due to walking and heel drop. This study attempts to compare the human Perception level of two different vibration sources. Also, this study investigates the effect of damping on a Perception level under heel drop and walking vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1-5
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• 2007

A majority of piping vibration problems are induced by internal fluid pulsation; turbulent flow, vortex shedding at internal discontinuities, and pressure pulsation at equipment nozzles. The pulsation at the pressure sources resonates acoustically with the piping and the amplified pressure pulsation can generate shell mode vibration in the piping. Reheater attemperator piping supplies water from feedwater pump to reheater attemperator to control the boiler temperature. In normal operating condition, the high frequency shell mode vibration occurred in the piping with the high level of sound(105 ${\sim}$ 117 dB). The vibration sources are pressure pulsation in the pump nozzle and the frequencies are related to the blade passing frequencies. The objects of this paper are to analyze the cause of the high frequency vibration and to establish corrective actions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.537-542
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• 2006

This paper deals with the vibration isolation techniques for a large structure using experimental research. In the case of vibration isolation for the vicinity of a subway or a railroad station, most of vibration isolation techniques using isolation materials with high isolation efficiency only, have been applied. Therefore, the quantitative evaluation and design technologies are required for a vibration isolation of large structures. In this study, firstly, vibration characteristics due to train or subway are analyzed. Secondly, the performance of existing vibration isolation materials such as precision isolation material, elastomer is estimated through the experiments. Thirdly the performance of tire isolation material and its frame is tested and evaluated.