• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.97-100
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• 2005

Precise prediction of resonance frequency has been the subject of numerous papers related to Helmholtz resonator design because of its high performance at the frequency. The resonance frequency is dependent upon not only the internal dimensions of resonator but also the external boundary conditions such as the existence of other resonators in Helmholtz resonator array panel. However, the latter effect, which changes the external end correction of resonator, has not been well studied. We propose a formula to calculate the radiation impedance (or external end correction) of Helmhoitz resonator array panel. Any distance between adjacent resonators and any angle of Incidence can be allowed in the method. Numerical examples show how and how much the distance affects the resonance frequency of the panel. It is also found that the maximum absorption of the panel varies with the resonator arrangement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.861-866
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• 2012

Turbo-charger noise radiated from air intake part is one of the most important noise sources in diesel power plant. In this paper, intake noise control of the diesel power plant was studied using parallel baffle type silencer and concentric hole-cavity resonator simultaneously. Firstly, acoustical characteristics and attenuation performance for parallel baffle type silencer were investigated through theoretical approach and experimental method. Based on the results, optimal design of the parallel baffle silencer was suggested. Secondly, for reducing the low frequency noise contained in the intake noise, the concentric hole-type resonator was developed and the acoustic performance was verified from the test. By combining two types of silencers, it is expected that the overall insertion loss is about 50 dB. So, the combined silencer is very helpful in reducing the intake noise of diesel power plant.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.280-285
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• 2008

The helmholtz resonator with the perforated neck has demerits that the absorption performance is not so outstanding in an anti-resonance frequency and high frequency bandwidth. In order to overcome these problems, in the paper, a resonator combined with porous material is proposed. The absorption performances of resonators are measured by two-microphone method and estimated by transfer matrix method. The experimentally measured values of normal absorption coefficients agree well with the corresponding values from the transfer matrix method. Because of the porous material, it is shown that the absorption performance have been significantly improved in the anti-resonance frequency and high frequency bandwidth.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.288-291
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• 2004

The Helmholtz resonator is one of noise control elements widely used in many practical applications. However the resonator array system, which is sometimes used to reflect or absorb low frequency noise, has not been well studied. We have investigated the difference in sound absorption of the Helmholtz resonator array panel caused by change in the resonator arrangement. Experiments and numerical calculations for various Helmholtz resonator array panels are carried out and the results are compared each other. The comparisons show that the acoustic coupling between closely located resonators affects the performance of the sound absorbing system. Particularly, the distance between resonators has a significant effect on the broadness of the sound absorption coefficient.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.8 s.101
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• pp.924-930
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• 2005

Sound absorptive materials have good performance in high frequency range, not at low frequencies. Therefore it has been great challenge to develop a sound absorbing structure that is good at low frequency. We propose to use a Helmholtz resonator array panel for this purpose. A Helmholtz resonator is one of noise control elements widely used in many practical applications. The resonator is a simple structure composed of a rigid-walled cavity with a neck, but it has very high performance at resonance frequency. This paper discusses the sound absorption of Helmholtz resonator array panels at normal and random incidence. First, various experimental results are introduced and studied. Secondly, we theoretically predict the absorptive characteristics of the resonator away panel. The theoretical approach is based on the Fourier analysis for a periodic absorber. We believe that this method can be used to design a panel for low frequency noise control.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.951-956
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• 2008

Development of a silencer to Reduce Noise of Cross Talking in Apartment & Stores and air conditioning to fan Composite silencer application a specific of resonant type and expansion type, design possibility at reduction frequency. This silencer test result develop reduce 20dB of specification frequency. Pressure loss 2mmAq. This silencer is special of brief structure and possibility disjoint and joint, simple installation and maintenance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.104-110
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• 2008

Desire about agreeable habitat by enhancement of standard of living has been increased, and common complaints by transformer noise have been happening constantly. It has been installed resonator and sound-proof shutter in order to solve substation's noise problems. But those methods are not effective. Therefore, It is necessary to study transformer noise level that can satisfy noise regulation standard. In this paper described that predicted transformer noise level of substation boundary by operating situation at the indoor substation. Also, Presented most suitable noise level of transformer that satisfy noise regulation standard at the indoor substations through predicted results.

• 한국가스학회:학술대회논문집
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• 2005.10a
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• pp.98-103
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• 2005

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.330-331
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• 2009

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.491-500
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• 2016

The present study describes the acoustical characteristics of the new noise barriers which can control not only noise but also wind pressure by allowing air flow through barriers. In order to investigate the sound reduction index of the air transparent noise barrier, 17 models in total were examined with various size of openings and the volume of the resonators. As a result, it was found that the sound reduction index varies with the volume of the resonator and the area of the openings. Also, it was revealed that double layer of units has more sound reduction index than the single layer of unit at the frequency band from 400 Hz to 1250 Hz. This denoted that physical features of openings and resonators affect the sound reduction index of the air transparent noise barrier.