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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of the Acoustical Society of Korea
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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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Sum-Capacity Analysis of Multiple-Sensor Node Underwater Communications Using Time Reversal Transmission Method
Cho, Jung-Il ; Seo, Jong-Pil ; An, Jae-Jin ; Chung, Jae-Hak ;
The Journal of the Acoustical Society of Korea, volume 29, issue 5, 2010, Pages 295~302
This paper proposes a multiple access method based on Time Reversal Mirror (TRM) technique when the multiple sensor nodes exist. Proposed method increases system sum capacity using energy focusing effects of the TRM. Simulation results show that proposed algorithm obtains higher system sum capacity than Orthogonal Frequency Division Multiple Access (OFDMA), e.g., 27 bps/Hz higher than the OFDMA method when the number of sensor node is 30, the number of transducer is 8, and is SINR 16 dB.
Performance Analysis of Receiver for Underwater Acoustic Communications Using Acquisition Data in Shallow Water
Kim, Seung-Geun ; Kim, Sea-Moon ; Yun, Chang-Ho ; Lim, Young-Kon ;
The Journal of the Acoustical Society of Korea, volume 29, issue 5, 2010, Pages 303~313
This paper describes an acoustic communication receiver structure, which is designed for QPSK (Quadrature Phase Shift Keying) signal with 25 kHz carrier frequency and 5 kHz symbol rate, and takes samples from received signal at 100 kHz sampling rate. Based on the described receiver structure, optimum design parameters, such as number of taps of FF (Feed-Forward) and FB (Feed-Back) filters and forgetting factor of RLS (Recursive Least-Square) algorithm, of joint equalizer are determined to minimize the BER (Bit Error Rate) performance of the joint equalizer output symbols when the acquisition data in shallow water using implemented acoustic transducers is decimated at a rate of 2:1 and then enforced to the input of receiver. The transmission distances are 1.4 km, 2.9 km, and 4.7 km. Analysis results show that the optimum number of taps of FF and FB filters are different according to the distance between source and destination, but the optimum or near optimum value of forgetting factor is 0.997. Therefore, we can reach a conclusion that the proper receiver structure could change the number of taps of FF and FB filters with the fixed forgetting factor 0.997 according to the transmission distance. Another analysis result is that there are an acceptable performance degradation when the 16-tap-length simple filter is used as a low-pass filter of receiver instead of 161-tap-length matched filter.
A Numerical Method for Wave Reflection and Transmission Due to Local Non-Uniformities in Waveguides at High Frequencies
Ryue, Jung-Soo ;
The Journal of the Acoustical Society of Korea, volume 29, issue 5, 2010, Pages 314~324
In waveguide structures, waves may be partially reflected by local non-uniformities. The effects of local non-uniformities has been previously investigated by means of a combined spectral element and finite element (SE/FE) method at relatively low frequencies. However, since the SE is formulated based on a beam theory, the SE/FE method is not appropriated for analysis at higher frequencies where complex deformation of the waveguide occurs. So it is necessary to extend this approach for high frequencies. For the wave propagation at higher frequencies, a combined spectral super element and finite element (SSE/FE) method is introduced in this paper. As an example of the application of this method, wave reflection and transmission due to a local defect in a rail are simulated at frequencies between 20kHz and 30kHz. Also numerical errors are evaluated by means of the conservation of the incident power.
Speech Perception Boundaries of Korean Confusing Monosyllabic Minimal Pairs (CVC) in Normal Adults
Lee, Sung-Min ; Lim, Duk-Hwan ;
The Journal of the Acoustical Society of Korea, volume 29, issue 5, 2010, Pages 325~331
Categorical perception has been noted as characteristic properties of linguistic stimuli. In this study, Korean monosyllabic minimal pairs (consonant-vowel-consonant, CVC) were analyzed to understand perception boundaries between clinically confusing words. An efficient scheme has been developed to systematically synthesize temporal transition waveforms (11 steps) from one word to the target word for the pairs of /gom/-/gong/, /non/-/noon/, and /don/-/non/. The corresponding slopes, widths, and non-dominant factors of perception boundaries were analyzed for the total of 40 young normal subjects (20 males and 20 females). Results showed that there were relative pattern differences among confusing monosyllabic minimal pairs under categorical perception. For instance, the vowel difference within CVC pairs led to the lowest boundary performance in this experiment set. Data also indicated the potential application of the overall procedure for evaluating auditory functions and assisting rehabilitation programs.
The Effects of Empathy on Self-Esteem and Subjective Well-Being
Heo, Jae-Hong ; Lee, Chan-Jong ;
The Journal of the Acoustical Society of Korea, volume 29, issue 5, 2010, Pages 332~338
Previous studies have investigated the effect of empathy on relations. However, there have been few studies that found the effect of empathy on subjective well-being. This study aimed to investigate relations between empathy and subjective well-being. It was hypothesized that empathy had effects on subjective well-being in the mediation of self-esteem. Heo, J.H. and Lee, C.J. (2010) investigated the psychometric properties of EQ. However they did not do confirmatory analysis. So confirmatory analysis needs to be done in this study. Data was collected from 421 College student (male 192, female 225), and analyzed by SEM and path analysis. Results revealed that 3 factors model of EQ was proper, and EQ had effects on subjective well-being in the mediation of self-esteem. This suggested that empathy be a very important factor in our culture, and fulfillment of cultural task enhance self-esteem, which improve subjectve well-being. And cultural features should be considered in the study of empathy.
Design and Implementation of Crosstalk Canceller Using Warped Common Acoustical Poles
Jeong, Jae-Woong ; Park, Young-Cheol ; Youn, Dae-Hee ; Lee, Seok-Pil ;
The Journal of the Acoustical Society of Korea, volume 29, issue 5, 2010, Pages 339~346
For the implementation of the crosstalk canceller, the filters with large length are needed, which is because that the length of the filters greatly depends on the length of the head-related impulse responses. In order to reduce the length of the crosstalk cancellation filters, many methods such as frequency warping, common acoustical pole and zero (CAPZ) modeling have been researched. In this paper, we propose a new method combining these two methods. To accomplish this, we design the filters using the CAPZ modeling on the warped domain, and then, we implement the filters using the poles and zeros de-warped to the linear domain. The proposed method provides improved channel separation performance through the frequency warping and significant reduction of the complexity through the CAPZ modeling. These are confirmed through various computer simulations.
Improving Speech Quality of VoIP by Packet Prioritization
Yoon, Jae-Yul ; Park, Ho-Chong ;
The Journal of the Acoustical Society of Korea, volume 29, issue 5, 2010, Pages 347~353
In VoIP system, the speech quality is seriously degraded due to packet loss, and the degree of degradation by each packet loss depends on the characteristics of the corresponding packet. Therefore, it is possible to improve the speech quality of VoIP by selectively controlling the packet to be lost during transmission based on the expected degradation by the loss of each packet. In this paper, a new scheme to improve speech quality of DiffServ-based VoIP by assigning priority to each packet is proposed, and a method to determine the priority of each packet is developed. The performance of proposed method was measured in packet loss environment based on Gilbert model, and it was verified both objectively and subjectively that the speech quality is improved by the proposed method.