• 한국음향학회:학술대회논문집
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• 한국음향학회 2002년도 하계학술발표대회 논문집 제21권 1호
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• pp.525-528
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• 2002

The speed of sound, transmission coefficient, and attenuation are measured around the center frequency 1 and 2 MHz in solid materials such as bone, sediment, rubber, and Lucite materials. Common and different characteristics of such materials in the sound speed, transmission coefficient, and attenuation are discussed. Ambiguities in estimating such acoustic characteristics we also addressed. Ultrasonic properties of the first and second kind waves are clarified for different materials. Discussions are concentrated on classes of sound speed, broadband ultrasonic attenuation (BUA), and correlations of sound speed and BUA with apparent density. New correlations of inverse sound speed square and BUA with apparent density are suggested.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.772-777
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• 2004

Opera house acoustics were subjectively evaluated in order to investigate the effect of performance stage views on the audience's perception of the seat acoustics in an opera house. Nine seats from an existing opera house were selected for the auditory and/or visual experiments according to seating area distribution and acoustical parameters such as RT and $1-IACC_{E3}$. The recorded music, convolved from the impulse response, was presented with and without visual images of the stage. Subjects were asked to assess the auditory/visual descriptors and overall impression of the music at each seat. The results showed that good visual input helps produce a favorable impression of the acoustics, but a limited view degrades acoustical impression. The acoustical parameters in the tested seats were also investigated to find the relationship between the acoustical parameters and the visual/sound impression.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1993년도 학술논문발표회 논문집 제12권 1호
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• pp.190-194
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• 1993

In the ocean bubble layers play a significant role in the sound propagation as well as sound generation. Most of early works dealt with acoustic properties of the bubble layers with sharp flat boundaries. Bubble layers with sharp flat boundaries. Bubble layers with transition sublayers are more likely in the coean. In this paper a theory of sound propagation through plane bubble layers with transition sublayers at both borders was developed. It shows that the reflection and transmission coefficients depend on the thickness of transition sublayers. The theory with thicker transition sublayers shows weaker resonance properties of bubble layer. It gives better presentation for the peculiar behavior of the experimental data than that with sharp flat boundaries.

• International Journal of Aeronautical and Space Sciences
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• 제18권2호
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• pp.197-205
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• 2017

We investigate the slat noise generation mechanism by using large-eddy simulation (LES) and simple source modeling based on linearized Euler equations. An incompressible LES of an MD 30P30N three-element airfoil in the high-lift configuration is conducted at $Re_c=1.7{\times}10^6$. Using the total derivative of the hydrodynamic pressure (DP/Dt) acquired from the incompressible LES, representative noise sources in the slat cove region are characterized in terms of simple sources such as frequency-specific monopoles and dipoles. Acoustic radiation around the 30P30N multi-element airfoil is effectively computed using the Brinkman penalization method incorporated with the linearized Euler equation. The directivity pattern of $p^{\prime}_{rms}$ at $r=20c_{slat}$ in the multiple sources is closely compared to that obtained by the application of the LES/Ffowcs-Williams and Hawking's methods to the entire flow field. The power spectrum of p' at ${\theta}=290^{\circ}$ is in good agreement with the data reported in BANC-III, especially the broadband part of the spectrum with a decaying slope ${\propto}f^{-3}$.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.699-703
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• 1998

ISO/TC 43/SC 2(Building Acoustics)은 음향기술위원회의 건축음향분과로서 건축음향관련 규격을 제정하거나 개정하고 관련규격을 검토하는 운영위원회이다. ISO/TC 43/SC 2의 운영범위와 최근의 활동상황을 개괄적으로 소개하고자 한다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.170-171
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• 2003

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.208-209
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• 2012

This paper describes a comprehensive process and range of design tools and components for providing Improved perception of engine sound for mass production vehicles by the generation of finely tuned engine harmonics.

• 한국음향학회지
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• 제36권5호
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• pp.321-328
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• 2017

본 연구는 실제 콘서트홀에서의 무대음향측정과 무대 위 연주평가를 통해 듀엣연주자의 무대음향 선호요인을 도출한 것이다. 실험은 1186석 규모의 공연장에서 진행하였으며, 무대에는 오케스트라 쉘(Orchestra Shell)이 설치되었다. 실험에는 15쌍(총30명)의 연주자가 참여하였고, 선별된 5개 위치에서 순서에 따라 쌍을 지어 자기연주에 따른 각 지점의 선호도를 평가하였다. 그 결과, 무대 중앙의 선호도가 가장 높은 것으로 나타났으며, CS(Clarity at stage) 및 $ST_{Late}$가 가장 유의한 선호요인으로 도출되었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.87-91
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• 2005

The effects of the movable reflectors on the stage acoustics in Seoul's Sejong Performing Arts Center (3,048-seat multi-purpose hall, stage area of $270m^2$ within an orchestra shell) and Ceramic Palace Hall (440-seat concert hall, stage area of $105m^2$) were investigated. Acoustical parameters were evaluated by measuring stage and audience acoustics in the two halls. The study was primarily based on the stage support parameter STI proposed by Gade (Acustica 65, pp.193-203, 1989). Results showed that STI varied on the stage of the large hall according to the position of the reflectors, whereas STI did not vary in the small hall. In the large hall, a smaller clear stage area (bounded by the reflectors) yields an increase in both STI and other early energy measures. In the small hall, early energy decreases when its stage's surface diffusion was covered with specular reflectors.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 추계학술발표대회논문집 제23권 2호
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• pp.321-322
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• 2004

It is well known that the loss factor and Young's modulus are fundamental mechanical properties of materials. In this study. the dynamic characteristics of plastics are evaluated by using two different standard test methods which are ASTM E 756 and ISO 6721. Polycarbonate and acrylonitrile butadiene styrene were used as test specimens. In order to evaluate vibration of damping properties with temperature, we measured loss factor and Young's modulus of the specimens the temperature range between $-10^{\circ}C$ and $60^{\circ}C$. The Young's modulus for polycarbonate decreased significantly as increasing temperature, while the loss factor increased. However, the Young's modulus and loss factor of acrylonitrile butadiene styrene are varied somewhat with temperature.