• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.468-474
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• 2003

1. Schedule for the meetings of ISO/TC108 Mechanical vibration and shock and ISO/TC108/SC3 Use and calibration of shock measuring instruments 2. Minutes for the seventh meeting of ISO/TC108/WG23 Mechanical vibration and shock - Resilient mounting systems - Information for the application of source and receiver isolation (omitted)

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1126-1128
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• 2005

In this paper, electromagnetic vibration soruce of BLDC motor is analyzed, and a method of reducing vibration is presented. The vibration sources of BLDC motor are cogging torque and commutation torque ripple. The effectiveness of the proposed method were verified with experiments on FFT analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.628-632
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• 2001

In this paper, Firstly, it is shown that the bending mode vibration source of vertical pump system is comparatively large because resonance. Secondly in order to the bending mode vibration of vertical pump some practical dynamic absorber have been developed and its effectiveness is investigated as installing it at the vertical pump system practically.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.1
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• pp.42-49
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• 2009

In this paper, an alternative method was introduced to conduct a transfer path analysis for airborne noise. The method used the transfer function matrix composed of acoustic transfer functions that are referenced by the input voltage of a calibration source. A calibration factor which is converting a virtual voltage to source strength was deduced by vibro-acoustical reciprocity theorem. The calibration factor is then multiplied to the virtual input voltage to estimate the operational source strength. Three loudspeakers were used to noise sources of acrylic half car model. The method was applied to airborne noise transfer path analysis of the half car. The estimated source strength by transfer path analysis was compared the deduced source strength by vibro-acoustical reciprocity to verify the method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.6 s.111
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• pp.565-573
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• 2006

Acoustic analysis of a moving sound source required that the measured sound signals be do-Dopplerized and restored as of the original emission signals. The purpose of this research is development of beamforming technique can be applied to the rotor noise source identification. For the do-Dopplerization and reconstruction of emitted sound wave, Forward Propagation Method is applied to the time domain beamforming technique. And validation test were performed using rotating sound source constructed by bended pipe and horn driver. In the validation test using sinusoidal sound wave, sufficient performance of signal processing can be seen, and the effect of measuring duration for accuracy was compared. In the prop-rotor measurements, the acoustic source locations were successfully verified in varying positions for different frequencies and collective pitch angle, in hover condition.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.1-7
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• 2018

Recently, as interest in the internet of things has increased, a vibration energy harvester has attracted attention as a power supply method for a wireless sensor. The vibration energy harvester can be divided into piezoelectric types, electromagnetic type and electrostatic type, according to the energy conversion type. The electromagnetic vibration energy harvester has advantages, in terms of output density and design flexibility, compared to other methods. The efficiency of an electromagnetic vibration energy harvester is determined by the shape, size, and spacing of coils and magnets. Generating all the experimental cases is expensive, in terms of time and money. This study proposes a method to perform design optimization of an electromagnetic vibration energy harvester using an open source, big data platform.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.9
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• pp.920-929
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• 2008

The main noise and vibration source of the BLDC rotary compressor for air conditioner was analyzed by using the measurement of noise and vibration, noise contour, and experimental modal analysis. The source is presumed to the mechanical resonance excited by the electromagnetic attractive force of the BLDC motor. To reduce the excessive noise of the BLDC rotary compressor due to the mechanical resonance, air-gap enlargement and structural dynamic modification were applied in this paper. Its validations were conducted by the analysis of the electromagnetic attractive force which is generated by the BLDC motor and by the measurement of noise and vibration of the BLDC rotary compressor. By enlarging the length of air-gap and conducting the structural dynamic modification, the noise and vibration in the compressor was significantly improved by 4.5 dB(A) and 56 percent, respectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.8
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• pp.774-780
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• 2011

Recently, customers have been concerned about vehicle NVH depending on vehicle designing and manufacturing technologies development. In choosing vehicle, vehicle NVH is becoming the most important factor to customers. Especially, a seat is the final stage of vibration transfer path to passengers from all sources of vibration like engine, transmission and etc. And seat is the nearest component from driver's ear. For this reason, seat is the most important component that directly related to ride comfort for passengers. And driver can be influenced sensitively by BSR caused by seat. Thus, evaluating the vibration characteristics of vehicle seat and BSR caused by vehicle seat is necessary to reduce the seat BSR. The rattle noise occurred from seat has evaluated through sound source visualization and multi-dimensional spectral analysis - coherence function technique in this paper. Vibration characteristics of the seat has verified through modal test.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.11
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• pp.1177-1184
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• 2008

URN(underwater radiated noise) is one of the important performances of the battle ship related to the stealth. The main source of the URN is the structure-borne noise on the hull. And the pipe vibration transmitted to the hull is the main source of the structure-borne noise when the speed of the ship is lower than CIS(cavitation inception speed). In this paper, the vibration isolator(rubber mount) for the pipe system is described in order to reduce the structure-borne noise transmitted to the hull. The vibrations on the sea-water conveying pipes and their supports are measured in order to know how much vibration occurs on those positions. Based on these test results, the improved design of the rubber mount is suggested by the parametric study and is verified numerically with the pipe and hull model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.275-285
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• 1996

A noise measurement method of the multi-sound sources in a reverberation field with wave-guide is developed by experimental method. In the reverberation field, it is very hard to measure sound level or noise spectra of a certain sound source, when many sound sources generate noise simultaneously with a small space between them. Flexible wave-guide(tube) was used to measure noise level in a reverberation field. One end of the tube is attached to a sound source and the other end is closed with an anechoic terminal. Detailed method of the measurement and the source of error was considered as well.