• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.835-836
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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.196-197
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• 2012

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.791-796
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• 2010

Installing noise barriers is the most common method for reducing the highway traffic noise to the road side residential area. After the report about edge potential concept of a noise barrier, various types of noise reducing devices(NRDs) called "noise reducers" have been suggested for getting more shielding effect on the top of highway noise barriers. But, it has been doubtful about effect of the NRDs in field because there was no appropriate and unified method to estimate the acoustic performance by using field measurement of the NRDs in Korea. In this study, the authors have considered to setup a practical method to test and estimate the acoustic performance of NRDs. For eliminating the noise reduction effect of the NRDs height itself, the source and measuring points are adjusted as highly as the NRDs height. For the frequency weighting in the estimation of the NRDs effect, the highway noise spectra were measured at asphalt and concrete road side and then averaged for a unit spectral parameter.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.488-492
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• 1997

원자력 발전소의 공조 시스템에 설치되는 덕트형 소음기를 설계.제작하여 감음성능 시험, 내진해석, 내진시험, 난연시험 및 기밀시험 등을 수행하여 각각의 요구조건에 적합한 소음기를 설계.제작한 결과 원자력 발전소에 기 설치된 소음기와 동등한 성능을 갖는 것으로 나타났다. 소음기를 설계, 제작, 시험하는 과정에서의 노-하우를 바탕으로 어떠한 요구조건에도 만족하는 제품을 국내에서 설계.생산할 수 있는 기술 확보에 있다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.35-40
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• 1990

본 연구에서는 덕트내 입사파와 반사파의 분리가 가능한 2개 마이크로폰법 (Two-sensor Method)의 입사파와 반사파의 분리측정 정밀도를 확인하고 이 방법에 따라 입사파 음향인텐시티만을 분리 측정하여 투과손실을 구하고 이 값과 ASTM E 477규격에 따른 삽입손실 측정값을 상호 비교검토하고자 한 다.

• The Journal of the Acoustical Society of Korea
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• v.8 no.1
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• pp.59-66
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• 1989

This study aims to provide the basic data useful in assessing indoor-noise and designing sound devices in office buildings of HVAC system. The measurements of HVAC noise were carried out in office room and mechanical room. The performance of absorptive chamber and side branch was also estimated in the office buildings which have HVAC noise problems. The results of experiments show that the NR value of indoor HVAC noise is rather higher than that of ISO recommendations at the frequencies below 500Hz. In addition, the results indicated that the absorptive chamber attenuates noise over broad band frequencies and side branch reduces noise at the special resonant frequency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.596-597
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• 2011

본 연구에서는 선박용 디젤엔진의 저주파수 대역 소음저감을 위해, 엔진 점화주파수 성분을 제어하고자 연장관과 헬름홀쯔 공명기, 흡음재로 구성된 소음기를 제안하고, 성능테스트를 통해 저감성능을 확인하였다. 개발된 소음기의 성능 계측결과, 저주파수 대역에서 5dB 이상의 감음성능을 확인할 수 있었다.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.653-660
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• 2008

The purpose of this study is to analyze the optimal mix design of the sound absorption material that is made from perlite and various binder systems for noise barrier wall. The polymer cement slurry which is made from two types of polymer dispersions, and silicone type inorganic material are used as binder. The test specimens are prepared with various polymer cement ratios, binder ratios, and tested for strengths, freezing and thawing and sound absorption performance by the tube and the reverberation room methods. From the test results, the difference of sound absorption coefficient by the tube method is a little recognized, however, noise reduction coefficient (NRC) of test specimens bound by the polymer cement slurry is in the ranges of 0.48 to 0.51. They are a little higher than those bound by cement only, and are lower values than recommended value of 0.7 by the Ministry of Environment. However, the sound absorption coefficient of test specimens at low frequency range of 250 to 500 Hz by reverberation room method shows very high values as 0.84 to 1.00, and 0.57 to 0.77 at the high frequency. The test specimens with polymer cement slurry binder have a good balance between performance and cost, and have proper properties in strengths, freezing and thawing resistance as sound absorption material for noise barrier wall. It is apparent that the good sound absorption material can be produced according to the optimum mix design that is recommended from this study.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.1
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• pp.108-115
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• 2001

The noise level of the navigation bridge as well as topside of the superstructure is dominated by the exhaust gas noise of the high-powered main engine and generator engine of special purpose vessels. In the case of the noise radiated from the top of the funnel. the exhaust pipe can be fitted with a silencer to reduce the propagated noise level. This paper is prepared based on an experimental performance test results of the silencers for generator-engine exhaust gas noise with consideration of air velocity. Two silencers were examined to check the performance of noise reduction in cases of air velocity 0m/s and 32m/s. In the sound reduction test, 400mm and 600mm diameter pipe ducts equipped with an axial fan were used as exhaust gas pipe system in the actual ship. The test procedure and results are presented in detail.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.372-375
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• 2006

건설 공사장에서 발생하는 건설장비의 소음을 저감하여 공사장 인근 지역의 생활환경에 미치는 소음영향을 최소화할 수 있도록 건설업체에서는 최대한의 노력으로 가설방음벽을 설치 운영하고 있으나, 설치된 가설방음벽의 효과분석 및 운영방법에 대한 검토가 부족하여 효율적인 소음저감대책으로서의 가설방음벽 운영이 어려운 실정이다. 따라서, 본 연구에서는 가설방음벽의 기초데이터의 확보와 소음해석을 통한 효율적인 운영방안을 제시하며, 설치기준에 관한 방안을 제시하고자 한다.