• Journal of KSNVE
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• v.8 no.1
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• pp.36-40
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• 1998

공항주변지역의 항공기 소음영향은 항공기 1대에 의한 소음크기나 시끄러움보다는 항공기가 계속하여 반복 운항하는데 더욱 큰 영향이 있다.그래서 ICAO가 1971년에 공포한 Annex 16 Aircraft Noise중에서 다수의 항공기에 의해 장기간 연속폭로 된 소음척도로서 EPNL에 항공기 운항회수와 운항시간대등을 고려한 WECPNL(가중 등가속 감각 소음 레벨 : Weighted Equivalent Continuous Perceived Noise Level)이 제안되었다.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.314-319
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• 2021

The measurement of the Underwater Radiated Noise (URN) for the underwater vehicle should consider both the acoustic interference due to the surface reflection and the calculation of the Closet Point of Approach (CPA). In this paper, I tried to analyze the underwater vehicle's URN using the Lloyd's mirror effect. First, the theoretical Lloyd's mirror pattern was compared with the sea trial result, and the sea trial results corresponded well with the theoretical predicted pattern. And then the CPA distance could be estimated by the Lloyd's mirror pattern. As a results, acoustic source level shows the spectral fluctuation due to the acoustic interference of the Lloyd's mirror effect.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.197-201
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• 1983

Underwater ambient noise level was measured at two points near the Youngil Bay. The environmental characteristics depend upon oceanographic conditions of sound propagation ana its implication on the source of ambient noise. Some noise sources were estimated, and the effect of the oceanographic conditions on the noise level variation had been considered. The results were as follows : 1) At the nearshore station of Youngil Bay, the ambient noise level in the near bottom(45m) was lower than that of the near surface(10m) by 15dB. This difference was due to spherical spreading from the upper to the lower layer. 2) At the open sea station which is located outside of the thermal front existing near the Youngil Bay, the ambient noise level of the upper layer(20m) was higher than that of the lower layer (100m) by $8{\sim}12dB$ below 50Hz and $15{\sim}23dB$ above 50Hz. 3) Above 60Hz the ambient noise level at the nearshore station was higher than that of the open sea station, while below 60Hz, the result was reverse. It appears that a boundary layer existed between the two stations.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1193-1197
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• 2005

The low frequency noise below 200 Hz, including inaudible infra-sound, is known to affect human physiology ; circulation, respiration, nerve, endocrine, etc. Legislation has been introduced in several countries regarding evaluation guideline and measurement method of low frequency noise. In this work, low frequency characteristics of the Seoul subway transportation system was investigated in terms of the noise level and spectrum in the interior of running passenger car and the subway station. The interior sound pressure level of the passenger car was between 60 and 105 dB in the frequency range of $1{\sim}200\;Hz$ and varied with car speed. The marked sound pressure level peak at 8 Hz, infra-sound, observed for the most of Lines is shown to correspond to the resonance frequency of passenger car. The level of station platform noise was lower than the interior noise of running car because of the lower speed at arriving/departure. The results indicated that the interior noise level of running passenger car was inside the oppressive feeling region, proposed by Ochiai, in the frequency range of $20{\sim}80\;Hz$ which makes a little concern.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.415-416
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• 2004

이어도 해양과학기지에서 해수중으로 청음기를 내려 2004년 7월에 3일간 연속적으로 수중 배경소음을 녹음 하였다. 측정된 주파수스펙트럼을 통계처리하고 또한 시계열 신호의 특성을 분석하였다. 해상 풍속도 관측하였다. 전체적으로 한반도 주변 해양의 배경소음에 비해 상대적으로 소음레벨이 작은 경향을 보였다.

• Journal of the Korean GEO-environmental Society
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• v.12 no.3
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• pp.27-35
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• 2011

This study investigated a sound reduction degree by each soundproofing materials and the sound pressure level of a main frequency range to develop soundproofing facilities installed for reducing sound in a tunnel blasting. The frequency range and sound pressure level of soundproofing materials(eg. sand and water etc.) mainly used at a working spot were measured using the experimental apparatus considered with blasting situation. The full scale pilot test was also carried out using developed soundproofing facilities in this study. And the performance of developed soundproofing facilities was analyzed. As a result, the developed soundproofing facilities using water in sound insulation materials could reduce about 10dB(A) of blasting noise in compare with the existing soundproofing facilities.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.9 s.102
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• pp.1092-1099
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• 2005

This experimental study deals with the characteristics of LCD or PDP TV set noise, which are differ form those of CRT TV set. These characteristics are most important for establishing the effective method to reduce noise level, searching for the appropriate exposure level and evaluation method of LCD or PDP TV set noise. This study adopt two measurement method to specify the power level of LCD or PDP TV set noise in anechoic room(ISO 3741) and reverberation room(ISO 3745) . Comparing with each results of the two method, the reverberation room method is more simple in measuring and calculating the power level. And the subjective response test are carried out to select the pair of appropriate adjectives to present the characteristics of LCD or PDP TV set noise. The pair of 17 adjectives are selected from the 168 adjectives which are used in presenting the sound and noise form literature.

• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.162-167
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• 2024

Low frequency noise emitted by wind turbines is one of the most noise complaints. In this study, the reliability of the models was examined by comparing the measured sound pressure levels with the predicted levels based on Denish model and commercial programs of the SounPLAN and the ENPro based on ISO 9613. As a result of applying it to representative 3 MW wind turbines, on lnad, the measured and the predicted values differed within a maximum of 5 dB in the frequency range of 12.5 Hz to 80 Hz. It may be due to the change in the acoustic power levels because the wind turbines have been in operation for more than 7 years. However, considering that the Boundary Element Method (BEM) predicted value, which is known to be the most accurate in the low frequency band, the predicted values are well matched within 2.5 dB, the models of this study are expected to be used as deviation within 3 dB.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.768-771
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• 2004

항공기 소음평가 방법에 있어 전혀 다른 소음특성을 갖는 군용 항공기 소음과 민간 항공기 소음을 환경부에서 고시한 소음 진동공정 시험방법에 의거하여 소음을 측정하고 평가하는데는 많은 문제점이 뒤따른다. 따라서 본 연구에서는 민간 항공기와 군용 항공기 소음의 측정 및 평가방법에 대한 문제점들을 고찰하였다. 연구결과로 부터, 민간 항공기나 군용 항공기의 정확한 소음측정을 위해서는 동특성을 빠름(Fast)으로 설정하여 측정하는 것이 바람직한 것으로 확인되었다. 또한 등가 소음도를 측정하여 항공기 소음을 평가하는 방식은 민간 항공기 소음평가시에는 적절하지만, 이를 군용 항공기 소음에 적용하여 평가할 때에는 상당한 오차를 포함하는 것으로 조사되었다. 그리고 군용 항공기 이 착륙지점에서의 소음 지속시간이 대부분 30초를 초과하는 것으로 조사되었기 때문에, 군용 항공기 소음평가시에는 지속시간에 대한 보정이 반드시 반영되어야 할 것으로 사료된다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.722-727
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• 1998

본 연구는 도시 인근발전소의 소음 유발 기기에 의한 환경소음의 실제적인 기여도를 평가하고 더욱 쾌적한 환경조성방안을 도출하기 위하여 수행되었다. 발전소 경계의 수음자소음을 기초로 각종 기기의 주파수 분석을 통하여 소음 유발 기기를 규명하고 소음원의 주 주파수 및 크기를 구하였다. 소음원의 전파경로를 파악하기 위해 소음레벨의 분포도를 구하였으며, 측정치와도 잘 일치함을 보여주었다.