• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.447-450
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• 2005

Multi-channel artificial reverberation algorithm to control perceived direction and distance is described in this paper. In conventional algorithms using IIR filters, reverberation time is the only parameter to be controlled. Moreover, since the convolution-based conventional algorithms apply only same impulse responses, but not considering sound localization, it was not realistic enough. The new algorithm proposed in this paper utilizes early reflections segmented according to the azimuth from which direct sound comes and controls perceived direction by panning the direct sound, and controls perceived distance by adjusting Energy Decay Curve (EDC) of reverberation and gain of the direct sound. In addition, the algorithm enhances Listener Envelopment(LEV) to make late reverberation incoherent among channels.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.275-285
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• 1996

A noise measurement method of the multi-sound sources in a reverberation field with wave-guide is developed by experimental method. In the reverberation field, it is very hard to measure sound level or noise spectra of a certain sound source, when many sound sources generate noise simultaneously with a small space between them. Flexible wave-guide(tube) was used to measure noise level in a reverberation field. One end of the tube is attached to a sound source and the other end is closed with an anechoic terminal. Detailed method of the measurement and the source of error was considered as well.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.492-497
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• 2006

This study gives the results of the measurements and analysises of the reverberation times in a small room such as apartment houses. We measured the RT by changing measurement conditions, which were sound sources. sound source's positions, receiving point & height, sampling time and so on. The critical factor affecting reverberation time was sound source in unoccupied houses and the reverberation time differences between result of RT using impulsive and interrupted sound source was 0.3sec at 500Hz frequency. And the difference of RT due to sound sources affected the sound insulation such as apparent sound reduction index and sound level difference about 1dB at each frequency in unoccupied houses.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1652-1657
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• 2010

This paper analyzes optimal stirrer parameter to improve field uniformity in a mode-stirred reverberation chamber. Stirrer parameter is varied about stirrer height and stirrer angle. Also we analyze quality factor, number of excited modes and stirrer efficiency that affect field uniformity. The results show good performance as higher as stirrer height. Isotropic field distribution is formed at $45^{\circ}$ stirrer angle. When stirrer angle varies, scattering characteristic of incident wave are changed. So electric field distribution in a mode-stirred reverberation chamber is also changed. Therefore, it affect field uniformity. The results expect to help that designs stirrer for get better field uniformity. Immunity test performed designed mode-stirred reverberation chamber for semiconductor that categorized by technology. Test result shows that good recurrence compared wave-guide immunity test.

• The Journal of the Acoustical Society of Korea
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• v.18 no.4
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• pp.65-70
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• 1999

To examine the space variances of the sound pressure level for five different types (normal frequency spacing) of reverberation rooms, simulations were conducted using the Finite Element Method. In case of infinite surface impedance, nonrectangular reverberation rooms showed small Standard Deviations across the band of frequency, and in case of finite surface impedance, ideal rectangular reverberation rooms showed the similar results as those in irregular shaped reverberation rooms.

• The Journal of the Acoustical Society of Korea
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• v.19 no.1
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• pp.48-53
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• 2000

To analyze a room reverberation, many objective parameters have been suggested as measures of subjective perception in concert hall acoustics. However, it is difficult to understand the relationship among the individual parameters and to have a whole image of them. In this paper five primary objective parameters were selected and a reverberation model based on them was established by the reverberation decay curve. The proposed model was interpreted geometrically in terms of subjective characteristics. And finally we discuss the usefulness and the limitation of the model when it is applied to the analysis and.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.242-242
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• 2013

Recently, importance of working environment is increased in commercial vessel and offshore structure. Marine facility design and ambient environment condition are influenced to enhancing human performance and reducing human errors. Consequently, the quality of accommodation where offshore facility crews sleep, eat and relax will influence their job performance and overall sense of comport and well-being. Therefore, adequate acoustic isolation between adjacent spaces is normally required to achieve satisfactory internal noise levels, acoustic privacy and speech intelligibility. In this study, the reverberation time is investigated in the public areas where there are not provided the information of material's noise reduction coefficient (NRC). The experiment of reverberation time is rarely performed for the various type public areas in a marine structure. Therefore, the reverberation time in a vessel is investigate in order to evaluate the room's noise reduction coefficient (NRC) in a public area.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.1 s.106
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• pp.34-39
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• 2006

For the evaluation of the normalized impact sound pressure level, the reverberation time of the receiving room should be measured. This paper deals with the effect of the time constant of FFT analyzer and the measuring points on reverberation time. It is found that the time constant should be in the range between 10 ms and 35 ms. While the effect of measuring points on the reverberation time is significant when the bandwidth is narrow it is negligible in the evaluation of the normalized impact sound pressure level.

• Proceedings of the IEEK Conference
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• summer
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• pp.254-257
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• 2004

In shallow water, the performance of the operating active sonar systems is usually limited by reverberation. One of the measure to overcome the negative effect of reverberation is of selecting an adequate transmission pulse. SFM(Sinusoidal Frequency Modulation) pulse has been received a considerable attention as a candidate for suppressing the reverberation effect. In this paper, we analyze the detection performance of SFM pulse with respect to modulation frequency and bandwidth. To conduct the analysis. we synthesize the signal at the receiver considering. the transmitter. the receiver, and the propagation medium characteristcs. The simulations provide the optimum modulation frequency and bandwidth under the given situation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1104-1108
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• 2001

It is a difficult and important task to measure the reverberation time of an acoustic room with a short reverberation time. This paper presents a new technique to measure the reverberation time of an acoustic room with low value of BT60. The digital signal processing technique used to do this is the wavelet filter which is very flexible to design the 1/n octave band filter and has no delay problem compared with the conventional IIR digital filter. This method is successfully applied to the measurement of the reverberation time at low frequency band of famous concert halls in Korea.