• 한국주거학회:학술대회논문집
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• 한국주거학회 2004년도 추계학술대회 논문집
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• pp.367-371
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• 2004

The purpose of this research is furnishing of basic material for acoustic planning hereafter, after understanding the acoustic merits and demerits through measuring and analyzing on room acoustic of small performance hall. As the result of the measurement, those physical evaluation indexes such as SPL, RT, EDT, $D_{50}$, $C_{80}$, RASTI have being kept the satisfiable acoustic condition for the service of performance hall. Therefore, as small performance hall is regarded as equipped with sufficient volume of sound, reverberatory feeling and diffusive feeling, it judges as an excellent performance place, also it is considered that it could be utilized as a useful material when design so similar performance hall, hereafter.

• 한국음향학회지
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• 제13권1호
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• pp.93-98
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• 1994

본 논문은 모형실험법에 관한 것으로 실내음향과 차음에 있어서 건축음향분야의 모형실험의 의의와 동향 및 음향모형실험에서 실내음향의 물리적인 대응관계인 가장 기본적인 상사칙과 차음의 상사칙에 관하여 이론적으로 고찰하였다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2001년도 추계학술발표대회 논문집 제20권 2호
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• pp.219-222
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• 2001

Nondestructive nonlinear acoustic method in two dimensions is suggested as a useful tool for detecting defects in a composite layer-structured material. Spectrum level changes in fundamental and harmonic frequencies are observed in the presence of a layer type defect compared with in the absence of such a defect. It is proposed in this study that such spectrum changes we due to the mode conversion. The layer type defect makes different normal modes due to different boundary conditions in the thickness direction for the Lamb waves propagating in a layer-structured material. Specifically, the normal mode with the fundamental frequency in the case of the water-layer gap is converted to the normal mode with the second harmonic frequency in the case of the air-layer gap.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2001년도 추계학술발표대회 논문집 제20권 2호
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• pp.271-274
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• 2001

강의실의 언어 요해도에 관한 연구는 그 평가방법과 지표에 대한 주제로 꾸준히 이루어져 왔다. 기존의 지표들에서는 전체 음에너지에 대한 초기음에너지의 비율로 계산하거나(C80, D50) 주파수 대역별 음에너지의 감쇠율(RASTI)을 구하여 명료도를 평가하였다. 본 연구에서는 Autocorrelation Function (ACF)의 시간적 요소를 통해 강의실의 언어 요해도를 평가하였다. 먼저 시뮬레이션 대상 강의실에서 무향실 음원이 제시되었을 때 12개 수음점에서 음향특성을 측정$\cdot$분석하였으며 청감실험과 ACF 분석을 통해 강의실 요해도와의 상관관계 규명하였다

• 한국유체기계학회 논문집
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• 제19권2호
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• pp.11-15
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• 2016

In this study, the generation of the propeller hub vortex was analyzed and a PBCF(Propeller Boss Cap Fins) was designed to control the propeller hub vortex. A RANS(Reynolds-averaged Navier-stokes) approach is employed to predict the hub vortex characteristics. The hub profile is an important factor but only a small increase (1.9%) of efficiency was obtained with the hub profile modification. The propeller hub vortex was eliminated by installing the PBCF and as a result, the propeller efficiency was increased by 5.6%.

• 한국연소학회지
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• 제22권3호
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• pp.41-46
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• 2017

This study has numerically investigated the flame-acoustics interactions in the turbulent partially premixed flame field. In the present approach, in order to analyze the combustion instability, the present approach has employed the LES-based combustion model as well as the Helmholtz solver. Computations are made for the validation case of the partially premixed LIMOUSINE burner. In terms of the FFT data, numerical results are compared with experimental data. Moreover, Helmholtz equation in frequency domain is solved by combining CFD field data including the flight time from a nozzle to the flame zone. Based on numerical results, the detailed discussions are made for the essential features of the combustion instability encountered in the partially premixed burner.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.851-856
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• 2003

The study on the new measurement method of room acoustics is now in process in the ISO TC43/SC2/WG24 New standard(WD 18233) is dealing with the MLS, swept sinusoidal signal and impulse. This working group is composed of more than 20 specialists in 10 countries and the convener is professor J.H.Rindel in technical university of Denmark. The meeting of WG24 was held in the DIN, Berlin at 23rd. this september and the results was sent to the secretary of ISO TC43/SC2 for the circulation. Brief information of ISO/WD18233 and the result of this meeting is given here.

• 대한조선학회논문집
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• 제41권5호
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• pp.41-47
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• 2004

In this paper, floor impact noise reduction in cruise ship cabin is studied. A mock-up is built by using 6t steel plate, and two identical cabins are made where 25t panel is used to construct wall and ceiling inside the steel structure. Various floating floor systems are tested for which normalized impact noise is measured according to ISO 140-7. In addition, floor SBN (Structure-borne Noise) and floor damping are measured to study the effect of floating floor structure. It is shown that VL(Visco-elastic Layer) is more effective when hard plates are added above the VL.

• The Journal of the Acoustical Society of Korea
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• 제14권2E호
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• pp.65-72
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• 1995

주파수 응답 특성에 근거하여 스피커의 주관적인 성능을 평가하는 알고리듬을 제시하였고, 이 알고리듬에 의한 평가를 청취 실험과 비교하여 보았다. 청취 실험과 비교한 결과, 본 알고리듬에 의한 평가가 주관적 평가에 상당히 근접한 것을 볼 수가 있었다.

• Journal of Hydrospace Technology
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• 제2권1호
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• pp.18-26
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• 1996

It is normal practice to consider bending wave modes only, when one applies SEA (Statistical Energy Analysis) to ship structures because of complexities in SEA modeling and evaluation of coupling loss factors for inplane modes. According to the result of Tratch[1], the inplane wave modes becomes important for the analysis of a foundation structure as the distance from the source and receiver increases. In this paper, the effect of inplane wave modes on structure-borne noise propagation in ship structures is presented. It is shown that the inplane wave could increase the noise level more than 10 dB compared with the results without inplane wave modes at high frequency bands for compartments far from the source location.