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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
Editor in Chief :
Volume & Issues
Volume 1, Issue 1 - Jan 1982
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A rating method for sound quality of brahman bells
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 6~18
Korean brahman bells toll magnificent sound that would be a great vehicle which brings all beings to the sutras without lecturing mat and can lead them to the Land of Purity -Nirvana. The rating processes and their results of sound quality of the most beautiful Korean Brahman Bells of Sangwonsa, Bongduksa and Boshinkak have been presented in detail. This evaluation scheme is also a very effective measure in determining the beauty of sound not only of bells but also of any music.
An optimum stage-enclosure configuration for performers
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 19~26
n optimization technique is adapted to determine the stage enclosure configuration preferred by performers. The merit function which quantifies the ease of ensemble among the performers is derived from a set of qualitative conditions recommended by researchers of hall acoustics. The ray path tracing technique based on the modified method of images is used to analyze acoustical characteristics at any locations of performers in stage enclosure. The gradient search technique is employed to find the geometric parameters which maximmize the merit function. As an example, optimum stage enclosure configuration of the trio chamber music is obtained using the computer program developed. The developed technique can be used in the design of concert hall stage and also in forming a special enclosure with movable reflecting surfaces.
A Study on Spread Spectrum Communication Techniques Using SAW Convolvers
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 27~36
Determination of a New Cut-off Frequency Coefficient for Sound Propagation in the Surface Duct
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 37~44
In the mixed layer when the frequency approaches the cut-off frequency for the first mode of notmalmode theory, sound ceases to be trapped. Based on the data of surface sound velocities abtained during the period of 16 years in the Sea of Japan. A new cut-off frequency coefficient in the surface duct that will determine the miximum wave length for duct transimission of underwater sound has been calculated.
Improving LPC Analysis of Noisy Speech by Autocorrelation Subtraction Method
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 45~53
A robust linear predictive coding method that can be used in noisy as well as quiet environment has been studied. In this method, noise autocorrelation coeffieients are first obtained and updated during nonspeech periods. Then, the effect of additive noise in the input speech is removed by subtracting values of the noise autocorrelation coefficients of corrupted speech in the course of computation of linear prediction coefficients. When signal-to-noise ratio of the input speech ranges from 0 to 10 dB, a performance improvement of about 5 dB can be gained by using this method. The proposed method is computationally very efficient and requires a small storage area.
A 4800 BPS LPS Vocoder with Improved Exitation
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 54~59
We present an improved 4800 bps LPC vocoder system that virtually eleminates the buzzy effect from synthetic speech. Excitation signal in the new system is formed by adding high-pass filtered pitch pulses or random noise to a baseband residual signal that has been coded by pitch predictive PCM. Since the baseband residual is used as a part of excitation, the system is also robust to V/UV and pitch errors. According to our informal listening tests, the synthetic speech of the new system does not have the buzzy effect. As a result the vocoder speech quality is more natural than that of a conventioinal LPC vocoder.
Ameliolation of FFT
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 60~64
Redundancies in the computational procedure of the FFT by which the DFT is calculated are analized and a modified algorithm to reduce redundancies is proposed. An amended FFT fortran program adopting the proposed algorithm shows that the time necessary for DFT computation is decreased about one-tenth. The proposed method can be applied to the most of other transformation algorithms.
A Mothod for Detection of Vibrationi by the Ultrasonic
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 65~69
It is studied on the apparatus for detecting the amplitude and the frequency of the vidrating object by utilizing the Ultrasonic Doppler Effect, without having any effect on the vibratioinal cases. The output detected varing the distance between the transducers and the vibrating object, when the angles of the incidence and the reflection wave are equalized. AM demodulatioin is adapted for the detection of vibration, and the output errors are theoretically consideed. The accurate detection of vibration can be obtained, when the distance between them is 5cm to 20cm, the magnitude of amplitude is 1mm to 5mm, and the vibrational frequency range is 20Hz to 1KHz.
A Study on the Measurement of Vibration Frequency using Laser Doppler Effect
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 70~75
A Study on the Development of a New Muffler Component required in the Geometrically Constrained Space
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 76~81
To get minimum noise level by making full use of the constrained geometric space and being compatible with the minimum pressure-drop condition, 3-pipe through-flow system is designed by inserting a new pipe which is shaped a resonator in the cavity of 2-pipe system. As a result of the 1/3-octave-band frequency analysis for the noise reduction characteristics, this system is proved to have good sound attenuation effect in the high frequency region, so that it is found to be a useful component of a muffler.
Analysis of Engine Exhaust Muffler by Acoustic Theory
Okda, Josuka ;
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 82~91
To analyze the characteristics of engine exhaust mufflers by the acoustic theory is necessary for understanding the action of mufflers and for designing the mufflers. In many cases, the " Transmission Loss" is used in the analysis, but TL is not suitable for above purposes. In this paper the characteristics of the mufflers is analyzed by means of the four terminal constants of whole muffler system. After some approximation, the characteristics of engine exhaust mufflers is shown by the "D" in the four terminal constants. 20log│D│ can be easily constructed with the characteristics of each element of the muffler system. The analysis is done under the conditions of no loss and no gas-flow, so the result is approximate. But it is very useful for understanding the characteristics of the muffler system or each element of the system and for designing the muffler system.
Investigation of the Electron-phonon Interaction in Metals
The Journal of the Acoustical Society of Korea, volume 1, issue 1, 1982, Pages 92~96
In this paper, the interaction of electron and phonon in metals is expressed using Hamiltonian operator as follows. By excahnging phonon energy with in the vicinity of isotropical Fermi surface and using following electron and hole operators. We obtain the interaction of electron and phonon. And new Feynman Graphs are tried with the following conditions on. First, when state transfer state, phonon cannot be created. Second, when state transfer state, phonon cannot be destroyed. Third, when state transfer state, phonon can be created or destroyed. Fourth, when state transfer state, phonon can be created or destroyed.