• The Journal of the Acoustical Society of Korea
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• v.39 no.6
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• pp.606-614
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• 2020

In this paper, we analyze the influences of ship traffic and marine weather information on underwater ambient noise. Ambient noise is an important environmental factor that greatly affects the detection performance of underwater sonar systems. In order to implement an automated system such as prediction of detection performance using artificial intelligence technology, which has been recently studied, it is necessary to obtain and analyze major data related to these. The main sources of ambient noise have various causes. In the case of sonar systems operating in offshore seas, the detection performance is greatly affected by the noise caused by ship traffic and marine weather. Therefore, in this paper, the impact of each data was analyzed using the measurement results of ambient noise obtained in coastal area of the East Sea of Korea, and public data of nearby ship traffic and ocean weather information. As a result, it was observed that the underwater ambient noise was highly correlated with the change of the ship's traffic volume, and that marine environment factors such as wind speed, wave height, and rainfall had an effect on a specific frequency band.

• 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.

• The Journal of the Acoustical Society of Korea
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• v.34 no.6
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• pp.432-443
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• 2015

Coherence describing the similarity between physical quantities of two signals is a very useful tool to investigate the temporal and spatial characteristics of signals propagating in underwater acoustic waveguide. Ambient noise measurements were made by the vertical received array consisting of three hydrophones as part of the KIOST-HYU joint acoustics experiment, and the coherence for the underwater ambient noise was analyzed. In this paper, the coherence results in cases that the generator in the research vessel was off and turned on are presented. The coherence estimated in the case of the generator operation mode are compared to the predictions obtained using the theoretical model with the directional density function dominated by vertical components propagating downward from the ship. In the case of the generator switch-off, the results are compared to the model predictions with directional density function including the effects of sea surface noise and long-distance shipping noise.

• The Journal of the Acoustical Society of Korea
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• v.38 no.4
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• pp.378-386
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• 2019

Unlike ship noise that radiates from moving ships, wind noise is caused by breaking waves as a result of the interaction between the wind and the sea surface. In this paper, WNL (Wind Noise Level) was modeled by considering the noise source of the wind as the bubble cloud generated by the breaking waves. In the modeling, SL( Source Level) of the wind noise was calculated using the wind-speed data measured from the weather buoy operated in the coastal area of the East Sea. At the same time as observing the wind speed, NL (Noise Level) was continuously measured using a self-recording hydrophone deployed near the weather buoy. The modeled WNL according to the wind speed and the measured NL removing the shipping noise from the acoustic raw data were compared in the low-frequency band. The overall trends between the modeled WNL and the measured NL were similar to each other. Therefore, it was confirmed that it is possible to model the WNL in the shallow water considering the SL and distribution depth of bubble cloud caused by the wind.

• The Journal of the Acoustical Society of Korea
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• v.39 no.5
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• pp.390-399
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• 2020

Underwater ambient noise was measured at the eastern and western costal sites of Jeju Island where the water depth was 20 m by a hydrophone moored at mid-depth (10 m) for 4 months. These eastern and western sites were selected as potential sites for offshore wind power generator and the current wave energy generator, respectively. Ambient noise was affected by environmental data such as wind and wave, which were collected from nearby weather stations and an observation station. Below 100 Hz, ambient noise was changed about 5 dB ~ 20 dB due to low and high tide. Below 1 kHz, wave and wind effects were the main source for ambient noise, varying up to 25 dB. Ambient noise was strongly influenced by wave at lower frequency and by wind at higher frequency up to over 1 kHz. The higher frequency range over 10 kHz was influenced by rainfall and biological sources, and the spectrum was measured about 10 dB higher than the peak spectrum level from Wenz curve at this frequency range.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.41-42
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• 2001

본 연구에서는 규사채취작업으로 인하여 발생하는 수중소음과 모래 등의 유실이 작업현장 부근에 있는 정치망어장에 미치는 영향에 관한 연구 조사한 결과를 보고하고자 한다. 1. 조사대상 어장의 환경 - 조사대상 정치망어망은 양낙망 형태인 대형 정치망이었고, 경북 울지군 북면 나고리지선(37$^{\circ}$, 08.320' N, 129$^{\circ}$ 22.902' E)에 위치하고 있었으며, 어장면적은 500,000$m^2$, 어획대상어종으로는 대형 회유성 어종인 방어, 고등어, 오징어 외에도 주변해역에서 서식하는 돔, 넙치, 쥐치 및 기타잡어로 하고 있었다. (중략)

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.179-179
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• 2011

이동의 편리함과 주행안정성을 주기 위해 개발된 도로가 소음을 발생시켜 운전자 및 소비자의 쾌적성을 저해하는 요소로 작용하고 있다. 이러한 문제를 해결하기 위해 연도거리확보 또는 방음벽 등의 소음억제 방법을 사용하고 있으나 미관을 저해하고 용지사용이 비효율적이어서 외국의 경우 저소음 포장 연구를 통한 근본적은 소음 발생원을 차단하기 위한 노력이 진행되고 있다. 국내에서도 신도시 개발 등으로 도로건설에 따른 급속한 교통량 증가 및 차량의 고속주행으로 인하여 도시소음의 주요인으로 부각되고 있고 시민들의 높은 생활수준과 소음 환경에 대한 기본생활권 추구 성향이 증대되어 지역 주민의 교통소음 저감 대책 및 보상에 대한 법적 소송이 빈번히 발생하고 있어 차량 주행 소음 저감을 위한 방법으로 방음벽 설치가 널리 사용되고 있으나 이는 경제적 손실뿐만 아니라 도시미관을 해치는 문제가 발생하고 있다. 도로사업의 환경성 강화는 국토해양부의 2009년 주요도로정책 중 하나일 정도로 국가정책의 중요한 지침으로써, 향후 추진되는 신도시 및 단지조성공사 시 도로 환경성과 소음, 진동, 그리고 생태통로에 대한 친환경 도로설계 및 시공 등에 적절히 대응하기 위하여 교통소음을 개선하기 위해서는 교통소음 발생 요소를 파악하고 신도시 및 단지조성시 주변도로에 친환경적 포장공법 설계기술의 개발 및 적용을 위한 단계적 연구가 필요하다. 따라서 본 연구에서는 친환경 저소음 포장공법의 종류에 대하여 알아보고자 한다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.1
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• pp.11-17
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• 1987

This paper describes an availability of the teltmeter device made as a trial to measure the under-water noise, and the results of the test. This telemeter device adopts FM-FM system, and its main carrier wave is 146.2MHz. The trans-mission power is about 1w, and the available distance of transmission is 2.5KM. The timer built in the telemeter device controls transmission time and pause time automatically by the R-C time-constant. The former is 30-32 seconds and the latter is 10-12 seconds. The underwater noise in the set net fishing ground and at the breeding tank was measured, and recorded simultaneously on land and at sea with the telemeter device. When the input voltages of the transmitter is 100-300mV, the value of telemetering ambient noise and bio-acoustic underwater noise well agreed with that of the direct measurement. And the teleme-tered underwater noise decreases in proportion the distance between the transmitter and receiver.

• Proceedings of KOSOMES biannual meeting
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• 2007.05a
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• pp.109-113
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• 2007

Yacht have an high powered main engine relatively light hull, so the noise generated from the engine have a bad influence upon the crew and passenger. Recently, cruise yacht is made an attempt by domestic production skill, however the insulation skill of the noise made by the main engine is not satisfy the real purchasing power of the buyer. Like this, yacht cabin's noise level is becoming the barometer to decide the purchase. the method to insufficient. However, if we use the skill of the monitoring equipment and the genetic algorithm system, the circumference of the main engine can be enclosed by an high quality absorbtion wall and the noise levels of the cabins are improved. In this study, the sound absorbtion barrier is experimentally researched by change the volume and the length of the neck for the Helmholtz resonator as the resonator can absorb the noise effectively.

• The Journal of the Acoustical Society of Korea
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• v.31 no.8
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• pp.532-541
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• 2012

An underwater transient signal is distinguished from an ambient noise. Database for the underwater transient signal is required since the underwater transient signal shows various characteristics depending on acoustic features. In the paper, hence, sound mask-filter was applied to extract the transient signals which exist temporally and locally in the ocean. The standard signal was chosen and cross-correlated with the raw signal. A mask-filter for a transient signal was obtained using the threshold which was decided by the maximum likelihood method in the envelope of the cross-correlated signal. Using the sound mask-filter, the transient signal of a sea catfish {Galeichthys felis (Linnaeus)} was extracted from the underwater ambient noise. Similarly, the man-made signal was added into the noise and it was extracted by the same method. We also have demonstrated the significance of the transient signal through comparing the extracted signals depending on the standard signal. In the results, the proposed method, sound mask-filtering, could be utilized as a database construction of the transient signals in underwater noise. Particularly, this study would be useful to extract the wanted signal from arbitrary signals.