• 한국소음진동공학회논문집
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• 제16권7호
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• pp.729-738
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• 2006

Knowledge of acoustic transmission loss of acoustic window material has a great importance for the sonar performance in ship. The purpose of this study was to investigate the measurement and analysis method for the acoustic transmission loss of the acoustic window materials for sonar dome. The measurement and analysis were carried out in water with GRP material. Transmission losses were calculated based on integrated direct and transmitted signals. The experimental setup enabled to vary the angle of incidence. Thus the transmission loss data could be expressed as the function of frequency and angle of rotation. In this paper, diffraction effect of incident angle, size of specimen with test material, transmission analysis method and multiple waves as incident acoustic signal were discussed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1183-1189
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• 2006

Knowledge of acoustic transmission loss of acoustic window material has a great Importance for the sonar performance in ship. The purpose of This study was to investigate the measurement and analysis method for me acoustic transmission loss of the acoustic window materials for sonar dome. The measurement and analysis were carried out in water with GRP material. Transmission losses were calculated based on integrated direct and transmitted signals. The experimental setup enabled to vary the angle of incidence. Thus the transmission loss data could be expressed as the function of frequency and angle of rotation. In this paper, diffraction effect of incident angle, size of specimen with test material, transmission analysis method and multiple waves as incident acoustic signal wet-e discussed

• 한국소음진동공학회논문집
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• 제23권10호
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• pp.920-927
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• 2013

The requirement of acoustic performance about underwater acoustic material which is used in underwater environment more increases. Underwater acoustic material was made by viscoelastic material such as a rubber and a polyurethane etc. In order to increase an acoustic performance, several kinds of inclusions were added to viscoelastic material. In this paper, acoustic modelling and analysis techniques were introduced and the acoustic characteristics of underwater acoustic material were studied. Echo reduction and transmission loss were calculated with volume fraction of inclusion in the material. Also the characteristic impedance and the input impedance of underwater acoustic material were obtained and effects on the echo reduction and transmission loss of material were discussed.

• 대한조선학회논문집
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• 제58권6호
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• pp.375-381
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• 2021

This paper investigated sound characteristics by the delamination of an acoustic window. In detail, acoustic scattering and transmission characteristics on the delaminated acoustic window were estimated using an experimental and numerical approach. The experiment results showed that acoustic wave could lose its amplitude and take phase delay when it propagates the delaminated acoustic window. The numerical results showed that scattering phenomena occur on the delamination surface. The scattering characteristics presented differently according to the delamination size in the acoustic window. It also showed that transmitted sound distortion due to delamination could cause a direction detection error of SONAR by changing the position of the main lobe and the magnitude of the side lobe. In conclusion, the delamination has to be managed during the manufacturing process of acoustic windows.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.770-773
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• 2004

The transmission loss coefficient is very important acoustic property in parallel with absorption and acoustic impedance categorizing the acoustical materials, which can control the acoustical problems. At the same time, the transmission loss coefficient is a key parameter to choose the optimum material for the analysis of acoustical characteristics of material using SEA(Statistical Energy Analysis). In this paper, the acoustic transmission loss measurement system using 4-microphone TL tube is applied to the exhaust system, which is one of the most important acoustic control parameters in a car, based on the idea calculating the full transfer matrix. The theoretical background and measurement system are introduced, and finally the measurement results are verified.

• 한국소음진동공학회논문집
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• 제21권10호
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• pp.890-896
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• 2011

For developing acoustic window, transmission loss in accordance with incident angle was calculated and compared with measurement results. In design stage, the material choice of acoustic window is very important because the material is one of main parameters of transmission loss and structural strength. In order to analyze the effect of material properties on transmission loss, the parametric studies were carried out and the results were discussed in this paper. And, to verify the design specification of acoustic window, measurement was carried out and the results were compared and analyzed.

• 한국음향학회지
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• 제29권3호
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• pp.173-183
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• 2010

본 논문에서는 원통형 공동계의 음향 전달 특성에 대하여 이론적으로 검토한다. 원통형 공동계는 성덕대왕 신종의 음향 공동을 단순화시킨 모델로, 주 공동, 보조 공동 및 간극으로 구성되어 있다. 주 공동 내부에 점음원을 주고 내부 및 외부 음장에서의 주파수 응답 특성과 음향 모드를 구하였다. 그 결과는 SYSNOISE를 이용한 경계요소 해석결과와 비교하여 타당성을 확인하였다. 제안된 이론모델을 이용하여 간극과 보조 공동이 음향계의 공명 주파수와 음향 전달 특성에 미치는 영향을 규명하였다. 마지막으로 음원 주파수를 공동 내부에서 외부로 가장 잘 전달시키는 보조 공동과 간극의 조합을 결정하였다.

• 소음진동
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• 제7권3호
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• pp.457-466
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• 1997

The experimental and analytical study was conducted to determine the noise transmission characteristics of acoustically loaded steel plate of rectangular enclosure and to investigate the sound radiation characteristics through out the enclosure. The vibrations of acoustically loaded plate give rise to sound radiations and generate the reverberant space that the sound field exists very close to a vibrating plate. Acoustic transmission loss is measured from the incident intensity into the plate and the transmitted intensity through out the plate. Sound radiation patterns are measured from both acoustic intensity technique and surface intensity technique. Those resultant patterns and vibrational modes are vital in understanding the relations between vibration and noise in the near field out of vibrating plate.

• 한국소음진동공학회논문집
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• 제23권2호
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• pp.167-175
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• 2013

The wave propagation characteristics of an acoustic metamaterial composed of periodically repeated one-dimensional Helmholtz resonator array was investigated considering the effects of dimensional changes of the resonator geometry on the transmission coefficient and band gap. The effective impedance and transmission coefficient of the acoustic metamaterials are obtained based on the acoustic transmission line method. The designed acoustic metamaterials exhibit band gaps and negative bulk modulus that are non-existent properties in the nature. The band gap of the acoustic metamaterial is strongly dependent on the geometry parameters of Helmholtz resonators and lattice spacing. Also, a new type of metamaterial that is periodically constructed with two different resonators was designed to open the local resonance band gap without change of Bragg scattering.

• 한국정보통신학회논문지
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• 제5권1호
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• pp.202-211
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• 2001

본 논문은 수중에서 초음파를 이용하여 데이터를 전송할 때 전체 전송성능에 영향을 주는 Multipath를 수학적으로 분석하였고, 분석된 결과를 이용하여 다중경로의 영향을 고려한 수중 초음파 영상통신 시스템을 설계하였다. 주파수 제약환경에 강인한$\pi/4 QPSK$ 알고리듬을 채택하였고, 수중 초음파 통신에서 발생하는 신호의 Ringing 효과를 상쇄하기 위하여 FM 변조방식을 가미한 Hybrid 변복조 시스템을 설계하였다. 또한, 다중경로의 영향을 상쇄하기 위하여 적응 등화기를 설계하였으며, Baseline PEG 기법을 이용하여 수중영상 압축에 대한 연구를 수행하였다.