• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.605-610
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• 2013

This study proposes an analysis model to simulate a noise map and estimate noise distribution for a location and its surroundings of a power plant. The noise map analysis was executed by using ENPro that is a commercial program for environmental noise prediction. Experimental evaluation for the proposed analysis model was carried out by comparing the results from noise analysis and measurement at several major points of the power plant and residential areas.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.256-261
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• 2018

There are three types of noise generated inside the vehicle: BSR (Buzz, Squeak, Rattle). In this paper, we propose a classifier that automatically classifies automotive BSR noise by using features extracted from deep convolutional neural networks. In the preprocessing process, the features of above three noises are represented as noise-map using STFT (Short-time Fourier Transform) algorithm. In order to cope with the problem that the position of the actual noise is unknown in the part of the generated noise map, the noise map is divided using the sliding window method. In this paper, internal parameter of the deep convolutional neural networks is visualized using the t-SNE (t-Stochastic Neighbor Embedding) algorithm, and the misclassified data is analyzed in a qualitative way. In order to analyze the classified data, the similarity of the noise type was quantified by SSIM (Structural Similarity Index) value, and it was found that the retractor tremble sound is most similar to the normal travel sound. The classifier of the proposed method compared with other classifiers of machine learning method recorded the highest classification accuracy (99.15 %).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.490-495
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• 2009

An approach to 3D visualization of multiple sound sources has been developed with the application of a moving array technique. Frequency-domain beamforming algorithm is used to generate a beam power map and the sound source is modeled as a point source. When a conventional delay and sum beamformer is used, it is considered that 2D distribution of sensors leads to have deficiency in spatial resolution along a measurement distance. The goal of moving an array in this study is to form 3D array aperture surrounding multiple sound sources so that the improved spatial resolution in a virtual space can be expected. Numerical simulation was made to examine source localization capabilities of various shapes of array. The 3D beam power maps of hemispherical and spherical distribution are found to have very sharp resolution. For experiments, two sound sources were placed in the middle of defined virtual space and arc-shaped line array was rotated around the sources. It is observed that spherical array show the most accurate determination of multiple sources' positions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.9
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• pp.907-914
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• 2009

An approach to 3D visualization of multiple sound sources has been developed with the application of a moving array technique. Frequency domain beamforming algorithm is used to generate a beam power map and the sound source is modeled as a point source. When a conventional delay and sum beamformer is used, it is considered that 2D distribution of sensors leads to have deficiency in spatial resolution along a measurement distance. The goal of moving an array in this study is to form 3D array aperture surrounding multiple sound sources so that the improved spatial resolution in a virtual space can be expected. Numerical simulation was made to examine source localization capabilities of various shapes of array. The 3D beam power maps of hemispherical and spherical distribution are found to have very sharp resolution. For experiments, several sound sources were placed in the middle of defined virtual space and arc-shaped line array was rotated around the sources. It is observed that spherical array shows the most accurate determination of multiple sources' positions.

• Journal of Environmental Impact Assessment
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• v.20 no.4
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• pp.443-453
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• 2011

The purpose of present study is to develop a noise map around Korean Train Express (KTX) line. It is also to evaluate the high speed railway noise influence in neighboring areas around KTX. In order to develop the noise map, noise source modeling and 3-D noise radiation simulation have been performed by means of SoundPLAN program. The result of the noise map has been verified in comparison with the measured noise level. Noise measurements have been performed at 15 locations around KTX line. At each locations, 6 microphones were located 1.5m and 3m above the ground at each of 25m, 50m and 75 m distances from a center of the KTX track. The noise map showed clearly the high speed railway noise influence in neighboring areas around KTX line. The present study has also showed the noise could be reduced by using noise barriers constructed at severely noise-exposed locations.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.45-51
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• 2003

The ship's signal sound dispersed by air, obstacles, and noises due to absorption, reflection, and disturbances, respectively. It is one of the factors of marine casualties by misjudgment if receiving direction The last target of this study is to prevent inherent marine casualty using the analysis-evaluation techniques if the interferences of ship's signal sound. In this work, three-dimensional sound field control model is proposed to simulate various sound transmitting characteristics according to sea environments at sea The efficiency test of the model was carried out using VR-based ship simulator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.636-642
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• 2012

Delay-and-sum (DAS) Planar Beamforming has been a widely used Noise Source Identification Technique for the last decade. It is a quick one shot measurement technique being able to map sources that are larger than the array itself. The spatial resolution is proportional to distance between array and source, and inversely proportional to wavelength, thus the resolution is only good at medium to high frequencies. Improved algorithms using iterative de-convolution techniques offers up to ten times better resolution. The principle behind these techniques is described in this paper, as well as measurement examples from the automotive industry are presented.

• Journal of Digital Contents Society
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• v.9 no.2
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• pp.203-211
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• 2008

Due to the advance of H/W and S/W techniques to play 3D sound, the virtual space contented by 3D graphics and sounds can provide users more improved realities and vividness. However for the small 3D contents developers and companies, it is hard to implement 3D sound techniques because the implementation requires expensive sound engines, 3D sound technical understanding and 3D sound programming skills. Therefore 3D-sound-playing-interface is necessary to easy and cost-effective 3D sound implementation. Using this interface, graphics experts can easily add 3D sound techniques to their applications. In this paper, the followings are designed and implemented as a preliminary stage in the way of developing the 3D sound playing interface. First, we develop 3D sound S/W modules converting mono to 3D sound in PC based systems. Second, we develop the interconnection modules to map 3D graphic objects and sound sources. The developed modules in this paper can allow the user to percept sound source position and surround effect at the moving positions in the virtual world. In the coming works, we are going to develop the more completed 3D sound playing interface consisted of the synchronization technique for sound and moving objects, and HRTF.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.228-229
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• 2010

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.498-500
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• 2013