• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.152-157
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• 2008

Enclosure is widely used for the sound insulation in a ship. But it is very difficult to estimate the sound insertion loss for the enclosure because the sound field between the enclosure and the machine is so complex. Therefore, it is usually estimated experimentally. In this research, sound insertion loss of the enclosure is estimated by theory assuming that the sound field in the enclosure is reverberation field. And the results from the theory are compared to those from the experiment.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.894-903
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• 2014

Insertion loss prediction of large acoustical enclosures using Statistical Energy Analysis (SEA) method is presented. The SEA model consists of three elements: sound field inside the enclosure, vibration energy of the enclosure panel, and sound field outside the enclosure. It is assumed that the space surrounding the enclosure is sufficiently large so that there is no energy flow from the outside to the wall panel or to air cavity inside the enclosure. The comparison of the predicted insertion loss to the measured data for typical large acoustical enclosures shows good agreements. It is found that if the critical frequency of the wall panel falls above the frequency region of interest, insertion loss is dominated by the sound transmission loss of the wall panel and averaged sound absorption coefficient inside the enclosure. However, if the critical frequency of the wall panel falls into the frequency region of interest, acoustic power from the sound radiation by the wall panel must be added to the acoustic power from transmission through the panel.

• 한국소음진동공학회논문집
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• 제18권2호
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• pp.263-271
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• 2008

Compressor radiated noise is one of the dominant noise for the outdoor unit of the air conditioner. Therefore, air conditioner makers are trying to reduce it continuously. Even though noise absorption and isolation technology are one of the important parts for reducing the noise from the compressor, it is usually treated to the substitute technology when the noise from the compressor is very difficult to reduce by the compressor noise control only. In this paper, we focus on the property of the sound insulation for the cabinet and measure it applying the theory of the sound transmission loss and insertion loss of the simple enclosure. The insertion loss is evaluated by the experiments according to the thickness and the aperture of the partition in the cabinet.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.198-203
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• 2001

This paper discusses an experimental method for measuring the insertion loss (IL) performance of a double panel that are used in vehicles. Instead of two adjacent reverberation chambers which are generally used to measure the transmission loss (TL) of the large sound isolation materials, air-borne sound insulation tester was utilized to determine the IL and articulation index (AI) of standardized deadening materials. In comparison to reverberation chamber method, air-borne sound insulation tester method is more space-saving, more time-saving and more simple to the automotive acoustics. From the empirical results, it is verified that the performance of deadening materials is closely connected with thickness of panels, type of filling material that is filled into a double panel, and area ratio of double panel.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.1180-1184
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• 2001

This paper presents the effect of air gap insertion on the results in measuring the transmission loss of sound barrier by using APAMAT. The measured results show that air gap insertion improves transmission loss as by two-room method or intensity method. The measured results are compared with the predicted transmission loss using MATLAB GUI program based on the transfer matrix method. Predicted results were found to be in reasonable agreement with measured results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.646-650
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• 2001

In this paper, it is presented that the effect of air gap insertion in testing the transmission loss of sound barrier using structural vibration system. In this study, we use the APAMAT based on the structure-borne-noise. The measured results show that air gap insertion improves transmission loss as results of test based on the air-borne-noise. The measured results are compared with the predicted transmission loss using the transfer matrix method. The predicted results were found to be in reasonable agreement with measured results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.282-287
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• 2001

The test facility has been manufactured to predict the dynamic insertion loss and the pressure drop for ducted silencers based on ISO 7235. The qualification test of the test facility is necessary for determining the dynamic insertion loss and the pressure drop of the test silencer, and is surveyed the reflection coefficient for an anechoic termination, the velocity profile near the upstream connection to the test silencer, the reduction of the system silencer and the limiting insertion loss due to the flanking sound transmission along the duct walls.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.746-751
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• 1994

The four-terminal transmission matrix method has been widely used to estimate the insertion-loss. However, the predictins using the equations in the four-terminal transmission matrix method do not reflect a practical phenomenon accurately, In this paper, the correction method to derive the insertion-loss for a constant sound pressure source is presented. The method of correction to the four-terminal transmission matrix method was proposed by rewriting the real and imaginary parts as they depend solely on the flow velocity. Then the result was compensated for by adding the component of the temperature gradient.

• 한국음향학회지
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• 제41권3호
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• pp.302-311
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• 2022

방음벽은 도심구간의 도로 및 철도에서 환경소음 저감을 위한 가장 효율적 대안의 하나이다. 도로교통소음 등에 대한 방음벽의 삽입손실은 방음판의 음향투과손실, 흡음손실 및 방음벽의 회절감쇠에 의한 음에너지 저감량의 합으로 이루어진다. 방음판의 음향투과손실은 방음벽의 삽입손실을 결정하는 중요한 요인 중 하나로 방음벽의 성능을 결정하는 기본적인 지표이다. 그럼에도 불구하고 아직까지 우리나라는 방음판의 음향투과손실 측정방법에 관한 별도의 규격이 없다. 방음판의 일반적 재질에 대해 규정하고 있는 KS F 4770 시리즈의 한두 항목으로 가볍게 다루고 있을 뿐이다. 이 논문은 방음판의 음향투과손실 측정 및 평가 규격의 필요성에 대해 고찰하고, 실내 건축부재와 달리 외부공간에 설치되는 방음벽의 특성을 감안한 자유음장(무향실) 수음실에서의 측정방법을 모색하였다. 아울러 도로변이나 철로변 등 다양한 설치장소에 따른 방음효과를 간단히 표시할 수 있도록 기준 스펙트럼을 활용한 단일수치 평가법을 제안하였다.

• 한국소음진동공학회논문집
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• 제20권2호
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• pp.191-198
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• 2010

The noise by the construction activities is one of the main issues in Korea. To prevent the noise from construction site, construction company installs temporary noise barriers along the construction site boundary. Normally sound insulation performance ($R_w$) of the temporary noise barriers made by metal or plastic is between 18 and 31 dB and metallic noise barriers are around 5 dB higher than plastic noise barriers. Sound absorption performance (NRC) of the temporary noise barriers are between 0.20 and 0.59 so it's difficult to characterize their acoustic performance. In this study, it has founded that sound insulation performance of the temporary noise barrier has been improved about 3dB by stick the high density acoustic sheet and insertion loss of noise barrier is getting increased as the source and receiver approached the temporary noise barriers.