• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.620-627
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• 2023

Ship noise is one of the important factors for the living and health of seafarers, and ef orts to reduce ship noise are actively underway. There are two methods of noise reduction: passive noise Control (PNC) and active noise control (ANC). Unlike cars and airplanes, ANC is not widely used for noise reduction on ships. This study aimed to reduce the noise generated in the engine room by using soundproof panels and high-frequency vibration generators, as well as active noise control (ANC). For this purpose, an experimental model was made using an acrylic box, and the noise reduction effect was measured under four conditions. The experimental results are as follows: First, the soundproof panel had a noise reduction effect in all ranges from 55 dB to 85 dB. In the case of using a high-frequency vibration generator, there was no ef ect in the low noise range such as 55 dB(A), but there was a noise reduction effect in the high noise range such as 70.8 dB(A) and 85 dB(A).Second, when the soundproof panel and the high-frequency vibration generator were used simultaneously, the noise reduction ef ect was up to -2.2 dB(A). The results of this experiment were obtained from an experimental model made of acrylic, and they may be different from actual ships made of steel plate. In future studies, we plan to experiment using iron plate (considering the material, thickness, and structure) used in actual ships. We hope that this study will help to improve the living environment and health of seafarers on ships.

• The Journal of the Acoustical Society of Korea
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• v.41 no.4
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• pp.397-409
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• 2022

A model is developed for the calculation of sea surface generated ambient noise in the range dependent ocean environment. The sources are located in the horizontal plane all around and their depths are at the near-surface. The receiver array is located in the range dependent ocean waveguide. One-way coupled mode method is used to model the acoustic propagation between the sources and receiver in the range dependent waveguide, and the cross spectral density matrix of noise is derived. In simulation, noise intensity, beamforming result and coherence function are calculated from the cross spectral density matrix. These results are compared with those in the range independent environment. The modeling result shows the effect of the vertical directionality and asymmetry characteristics of the horizontal plane.

• The Journal of the Acoustical Society of Korea
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• v.32 no.6
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• pp.472-483
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• 2013

Actual maritime exercise for improving the capability of submarine sonar operator leads to a lot of cost and constraints. Sonar simulator maximizes the capability of sonar operator and training effect by solving these problems and simulating a realistic battlefield environment. In this study, a passive sonar simulator algorithm is suggested, where the simulator is divided into three modules: maneuvering module, noise source module, and sound propagation module. Maneuvering module is implemented in three-dimensional coordinate system and time interval is set as the rate of vessel changing course. Noise source module consists of target noise, ocean ambient noise, and self noise. Target noise is divided into modulated/unmodulated and narrowband/broadband signals as their frequency characteristics, and they are applied to ship radiated noise level depending on the vessel tonnage and velocity. Ocean ambient noise is simulated depending on the wind noise considering the waveguide effect and other ambient noise. Self noise is also simulated for flow noise and insertion loss of sonar-dome. The sound propagation module is based on ray propagation, where summation of amplitude, phase, and time delay for each eigen-ray is multiplied by target noise in the frequency domain. Finally, simulated results based on various scenarios are in good agreement with generated noise in the real ocean.

• Journal of KSNVE
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• v.16 no.4 s.82
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• pp.42-47
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• 2006

• Journal of KSNVE
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• v.23 no.5
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• pp.18-22
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• 2013

• Journal of KSNVE
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• v.23 no.5
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• pp.8-12
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• 2013

• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.38-45
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• 2021

In this study, changes in cavitation pattern and noise by air injection were investigated experimentally in a cavitation tunnel. Air injection system that can control the location and the amount of air was manufactured and installed in an elliptic wing that exhibits similar characteristics to those of a propeller blade. Various types of cavitation were simulated on the hydrofoil by adjusting the test conditions in the cavitation tunnel, and the changes in cavitation pattern and noise according to air injection were experimentally analyzed. It was shown that the noise characteristics varied depending on the position and the amount of air injection. This means that in order to apply the air injection technology to the propeller, it is necessary to optimize the air injection location and the amount of injection according to the cavitation characteristics.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.41-42
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• 2000

국제해양법이 제정된 이래 국내외의 정세변화에 따른 수산업의 침체에 대처해 나가기 위해서는 연안어장의 해양환경을 쾌적하게 조성하고 여기에서 조업하는 조업어선들의 구조와 운용설비 개선에 대한 대책이 마련되어야 한다. 특히 어선어업에 있어서는 어선에서 발생하는 소음은 선박에 종사하는 어업인과 어군에 직접적인 영향을 미치게 되므로 이들 영향을 최소화하기 위한 연구가 성실히 수행되어야 할 것이다. 본 연구는 소형어선의 항주 중의 수중소음의 어류에 미치는 영향을 파악하기 위한 기초자료를 얻고자 2000년 3월 2일∼4월 10일 여수연안에서 동일한 크기의 신조 소형 연안복합어선(GT 6.66)의 항주중인 선박의 수중소음을 측정, 분석한 결과이다. (중략)

• The Journal of the Acoustical Society of Korea
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• v.38 no.3
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• pp.247-255
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• 2019

In this study, to predict the noise of a submarine propeller which is going to become bigger and faster, the non - cavitating propeller noise was predicted based on the numerical analysis which considering the interaction of the hull - appendages - propeller. In order to predict the radiated noise of the propeller, the flow field for the entire region of hull-appendages-propeller was computed by CFD (Computational Fluid Dynamics). And the noise for the thickness noise and the load noise was numerically predicted using FW-H (Ffwocs Williams-Hawkings) acoustic analogy. Numerical noise prediction results were verified by model tests and showed good agreement with the measurement results in predicting total noise level and low frequency noise.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.65-66
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• 2001

선박 내에서 발생하는 소음은 그 크기와 특성이 매우 다양하게 나타난다. 최근 건조 선박의 고속화 추세로 인하여 선내 소음이 증가되고 있으며, 이러한 소음은 선박에 종사하는 선원들의 거주환경에 영향을 미치는 중요한 요소이다. 이에 관해서는 구보민, 유전민미 등의 연안어선에 대한 연구가 있으나 국내에서는 생활공간이 협소한 소형어선의 선내 소음과 그 대책에 관한 연구가 거의 없는 실정이다. (중략)