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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
The Journal of the Acoustical Society of Korea
Journal Basic Information
Journal DOI :
The Acoustical Society of Korea
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Volume & Issues
Volume 29, Issue 8 - Nov 2010
Volume 29, Issue 7 - Oct 2010
Volume 29, Issue 6 - Aug 2010
Volume 29, Issue 5 - Jul 2010
Volume 29, Issue 4 - May 2010
Volume 29, Issue 3 - Apr 2010
Volume 29, Issue 2 - Feb 2010
Volume 29, Issue 1 - Jan 2010
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Acoustic Power Measurement System of Array Probes for Ultrasonic Diagnostic Equipment Using Radiation Force Balance Methods
Yun, Yong-Hyeon ; Jho, Moon-Jae ; Kim, Yong-Tae ; Lee, Myoung-Ho ;
The Journal of the Acoustical Society of Korea, volume 29, issue 6, 2010, Pages 355~364
Considering biological safety, it is very important to measure acoustic power from ultrasonic array probe for diagnostic ultrasound imaging applications. In this paper, to measure acoustic power from each element on array probe for ultrasonic diagnostic equipment, we reconstruct and automate the acoustic power measurement system. The acoustic power from linear, phased and curved array were measured and analyzed. As a result of measurement, the effects caused by directivity of sound beam from curved array were founded. To remove these effects, we developed and applied the correction model. The proposed system is useful to evaluate characteristics of the acoustical output power of array probe.
Coherence Bandwidth and Coherence Time for the Communication Frame in the Underwater of East Sea
Choi, Dong-Hyun ; Kim, Hyeon-Su ; Kim, Nam-Ri ; Kim, Seong-Il ; Chung, Jae-Hak ;
The Journal of the Acoustical Society of Korea, volume 29, issue 6, 2010, Pages 365~373
For effective underwater digital communications, a frame structure is used, which includes pilots in time and frequency domains for channel estimation at a receiver. To estimate channel precisely, the each pilot should be located less than coherence time and coherence bandwidth. This paper measured underwater communication environments to provide coherence time and coherence bandwidth. Based on the measurement, the paper exhibits the calculated coherence time and coherent bandwidth is adequate by computer simulations.
FIR System Identification Method Using Collaboration Between RLS (Recursive Least Squares) and RTLS (Recursive Total Least Squares)
Lim, Jun-Seok ; Pyeon, Yong-Gook ;
The Journal of the Acoustical Society of Korea, volume 29, issue 6, 2010, Pages 374~380
It is known that the problem of FIR filtering with noisy input and output data can be solved by a total least squares (TLS) estimation. It is also known that the performance of the TLS estimation is very sensitive to the ratio between the variances of the input and output noises. In this paper, we propose a convex combination algorithm between the ordinary recursive LS based TLS (RTLS) and the ordinary recursive LS (RLS). This combined algorithm is robust to the noise variance ratio and has almost the same complexity as the RTLS. Simulation results show that the proposed algorithm performs near TLS in noise variance ratio
and that it outperforms TLS and LS in the rage of 2 <
< 20. Consequently, the practical workability of the TLS method applied to noisy data has been significantly broadened.
Salience of Envelope Interaural Time Difference of High Frequency as Spatial Feature
Seo, Jeong-Hun ; Chon, Sang-Bae ; Sung, Koeng-Mo ;
The Journal of the Acoustical Society of Korea, volume 29, issue 6, 2010, Pages 381~387
Both timbral features and spatial features are important in the assessment of multichannel audio coding systems. The prediction model, extending the ITU-R Rec. BS. 1387-1 to multichannel audio coding systems, with the use of spatial features such as ITDDist (Interaural Time Difference Distortion), ILDDist (Interaural Level Difference Distortion), and IACCDist (InterAural Cross-correlation Coefficient Distortion) was proposed by Choi et al. In that model, ITDDistswere only computed for low frequency bands (below 1500Hz), and ILDDists were computed only for high frequency bands (over 2500Hz) according to classical duplex theory. However, in the high frequency range, information in temporal envelope is also important in spatial perception, especially in sound localization. A new model to compute the ITD distortions of temporal envelopes in high frequency components is introduced in this paper to investigate the role of such ITD on spatial perception quantitatively. The computed ITD distortions of temporal envelopes in high frequency components were highly correlated with perceived sound quality of multichannel audio sounds.
Variations of Speed of Sound and Attenuation Coefficient with Porosity and Structure in Bone Mimics
Kim, Seong-Il ; Choi, Min-Joo ; Lee, Kang-Il ;
The Journal of the Acoustical Society of Korea, volume 29, issue 6, 2010, Pages 388~394
In the present study, polyacetal bone mimics with circular cylindrical pores were used to investigate variations of speed of sound and attenuation coefficient with porosity and microarchitecture in bone. The speed of sound and attenuation coefficient of the 6 bone mimics with porosities from 0 % to 65.9 % were measured by a through-transmission method in water, using a pair of broadband, unfocused transducers with a diameter of 12.7 mm and a center frequency of 1.0 MHz. Independently of the structural properties of the bone mimics, the speed of sound decreased almost linearly with the increasing porosity. The attenuation coefficient measured at 1.0 MHz exhibited linear or nonlinear correlations with the porosity, depending on the structural properties of the bone mimics. These results are consistent with those previously published by other researchers using bone samples and mimics, and advances our understanding of the relationships of the ultrasonic parameters for the diagnosis of osteoporosis with the bone density and microarchitecture in human bones.
The Invention of Reis Telephone and Its Problem of Speech Quality
Ku, Ja-Hyon ;
The Journal of the Acoustical Society of Korea, volume 29, issue 6, 2010, Pages 395~401
Since Philipp Reis succeeded in sending human voices through electric wires well ahead of Elisha Gray and A. G. Bell etc., he deserves to be acknowledged as the inventor of the telephone. Nevertheless, he did not enjoy any honor for his great invention while he was alive. Since he was working in a scientific community, his work was presented not as a patentable invention but as a scientific discovery. In addition, he used the intermittent electricity in accordance with the experimental tradition in European acoustics, occasioning the speech quality of his telephone to have a fatal shortcoming. On the contrary, Bell, who was a novice in electricity and acoustics, employed variable currents to transmit the sound signals, which guaranteed better speech qualities than Reis's.
A New Integrated Suppression Algorithm Based on Combined Power of Acoustic Echo and Background Noise
Park, Yun-Sik ; Chang, Joon-Hyuk ;
The Journal of the Acoustical Society of Korea, volume 29, issue 6, 2010, Pages 402~409
In this paper, we propose an efficient integrated suppression algorithm based on combined power of acoustic echo and background noise. The proposed method combines the acoustic echo and noise power by the weighting parameter derived from the decision rule based on the estimated echo to noise power ratio. Therefore, in the proposed approach, the acoustic echo and noise signal are able to be reduced through only one suppression filter based on the estimated combined power. The proposed unified structure improves the problems of the residual echo and noise resulted from the conventional unified structure where the noise suppression (NS) operation is placed after the acoustic echo suppression (AES) algorithm or vice versa. The performance of the proposed algorithm is evaluated by the objective test under various environments and yields better results compared with the conventional scheme.