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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of the Acoustical Society of Korea
Journal Basic Information
Journal DOI :
The Acoustical Society of Korea
Editor in Chief :
Volume & Issues
Volume 14, Issue 6 - Dec 1995
Volume 14, Issue 5 - Oct 1995
Volume 14, Issue 4 - Aug 1995
Volume 14, Issue 3 - Jun 1995
Volume 14, Issue 2 - Apr 1995
Volume 14, Issue 1 - Feb 1995
Volume 14, Issue 2E - 00 1995
Volume 14, Issue 1E - 00 1995
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Non-Parametric Texture Extraction using Neural Network
Jeon, Dong-Keun ; Hong, Sun-Pyo ; Song, Ja-Yoon ; Kim, Sang-Jin ; Kim, Ki-Jun ; Kim, Song-Chol ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 5~5
In this paper, a method using a neural network was applied for the purpose of urilizing spatial features. The adopted model of neural network the three-layered architecture, and the training algorithm is the back-propagation algorithm. Co-occurrence matrix which is generated from original imge was used for imput pattern to the neural network in order to tolerate variations of patterns like rotation of displacement. Co-occurrence matrix is explained in appendix. To evaluate this method, classification was executed with this method and texture features method over the city area and sand area, which cannot be separated with the conventional method mentioned aboved. In the results of this method and texture features proposed by Haralick the method using texture features was separation rate of 67%~89%. On the contrary, the method using neural network proposed in this research was stable and high separation rate of 80%~98%.
Finite Element Analysis of Capctive Silicon Pressure Sensors
Roh, Yong-Ae ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 12~12
Capactive miro pressure sensor is simulated with finite element methods to analyze the effect of geometrical variation on its performace. Sensor material is th silicon single crystal. The sensor consists of a disk type diaphragm and several bridges connected to a rigid frame. Structural variables in consideration are the thickness of the diaphragm and the bridges, radius of the circular plate, and the number of bridges. Results of static, dynamic and sensitivity analyses reveal the best structure of the sensor among the fifteen cases under investigation.
An Improved Parametric Estimation Method of High-Resolution Bispectrum
Park, So-Hyeon ; An, Chong-Koo ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 19~19
The maximum entropy method is a well-known parametric estimation method of the power spectrum with high-resolution for short-time signals. Although a parametric estimation method for the bispectrum was proposed in recent years, it is not easy to estimate the bispectrum with high resolution for relatively short-time signals of which the total length is about 1000 data points. In this paper, a bispectrum estimation method is proposed to estimate the high-resolution bispectrum even for the relatively short-time signals.
On the Use of a Parallel-Branch Subunit Mod디 in Continuous HMM for improved Word Recognition
Park, Yong-Kyuo ; Un, Chong-Kwan ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 25~25
In this paper, we propose to use a parallel-branch subunit model for improved word recognition. The model is obtained by splitting off each subunit branch based on mixture component in continuous hidden Markov model(continuous HMM). According to simulation results, the proposed model yields higher recognition rate than the single-branch subunit model or the parallel-branch subunit model proposed by Rabiner et al. We show that a proper combination of the number of mixture components and the number of branches for each subunit results in increased recognition rate. To study the recognition performance of the proposed algorithms, the speech material used in this work was a vocabulary with 1036 Korean words.
A Simple and Fast Pitch Search Algorithm Using a Modified Skipping Technique in CELP Vocoder
Lee, Joo-Hun ; Bae, Myung-Jin ; Kwon, Choon-Woo ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 33~33
Based on the Characteristics of the correlation function of speech signal, the skipping technique can reduced the computation time considerably with a little degradation of speech quality. To improve the speech quality of the skipping technique, we use the reduced form of the correlation function to check the sign of the correlation value before the match score is calculated. The experimental results show that this modified skipping technique can reduce the computation time in pitch search over 35% compared with the traditional full search method without quality degradation.
Application of the Polar Parabolic Equation Method for Sound Propagation over a Smooth Sea Mountain in the Ocean
You, Chul-Soo ; Yoon, Suk-Wang ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 37~37
The polar parabolic equation method (Polar PE) which introduces a series of "cascaded" boundary fitting coordinates into the parabolic equation method has been verified as a good numerical method for atmospheric sound propagation over a curved surface and hills. Polar PE is applied here to underwater sound propagation over a sea mountain assuming locally reacting boundary sea bottom and pressure release water surface for the boundary conditions. Calculations are presented for underwater propagation over a 450 m high sea mountain. Feasibility of Polar PE application for underwater sound propagation over a smooth mountain is discussed.
Detection and Location of Open Circuit Fault by Space Search
Han, Kyong-Ho ; Kang, Sang-Won ; Lee, In-Sung ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 43~43
In this paper a space search technique is used to detect and locate the faults of the circuit interconnections. The circuit interconnections are represented by the tree structure and the tree space is searched to detect and locate the open faults of the circuit interconnections. The breadth search is used to detect the open faults and reduce the space size. The depth search is used to locate the open faults.
PHDCM : Efficient Compression of Hangul Text in Parallel
Min, Yong-Sㅑk ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 50~50
This paper describes an efficient coding method for Korean characters using a three-state transition graph. To our knowledge, this is the first achievement of its kind. This new method, called the Paralle Hangul Dynamic Coding Method(PHDCM), compresses about 3.5 bits per a Korean character, which is more than 1 bit shorter than the conventional codes introduced thus far to achieve extensive code compression. When we ran the method on a MasPar machine, which is on SIMD SM (EFEW-PRAM)., it achieved a 49.314-fold speedup with 64 processors having 10 million Korean characters.
A Study on the classification of Underwater Acoustic Signal Using an Artificial Neural Network
Na, Young-Nam ; Shim, Tae-Bo ; Han, Jeong-Woo ; Kim, Chun-Duck ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 57~57
In this study, we examine the applicability of the classifier based on an artifical neural network (ANN) for the low-frequency acoustic signal in shallow water environment. The estimations of the Doppler shift and frequency spreading effect at 220 Hz reveal the frequency variation of less than 2 Hz with time This small variation enables the ANN-based classifier to identify signals using only tonal frequency information. The ANN consists of 4 layers, and has 60 input processing elements (PEs) and 4 output PEs, respectively. When measured tonal signals in the frequency 200-250 Hz are applied to the ANN-based classifier, the classifier can identify more than 67% of the signals for instantaneous frame and more than 91% for averaged one over 5 frames.
Loudspeaker Performance Evaluation Algorithm using Frequency Response Characteristic
Myung, Hyung-Gook ; Sung, Koeng-Mo ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 65~65
An algorithm for evaluating the subjective performance of a loudspeaker is proposed based on the frequency response characteristic. Objective ratings using the proposed algorithm were compared with the results of the listening test. It was verified that the ratings of the proposed algorithm showed a good correspondence with the results of the listening test.
Forward-Looking Ultrasound Imaging Transducer : I. Analysis and Design
Lee, Chan-Kil ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 73~73
The transducer section of the forward-looking ultrasound imaging catheter (FLUIC) consists of a circular piezoelectric element as a vibrator and a conical acoustic mirror as a perfect reflector. A small diameter piezoelectric transducer element is mounted on the side of a catheter's rotating shaft. The unique design of FLUIC provides the capability to form a two-dimensional image of a cross-section of vessel in front of the catheter, which is lacking in the present generation of intravascular ultrasound (IVUS) transducers, as well as a conventional side view image. The mirror configuration for the transducer section of the FLUIC is designed using an approximated ray tracing techniques. The diffraction transfer function approach  developed for the field prediction from primary sources is generalized and extended to predict the secondary diffraction characterstics from an acoustic mirror. The extended model is verified by simulation and experiment through a simple plane reflector and employed to analyzed the field characteristics of a FLUIC.
Diffraction-Limited Beam for One Dimensional Array in Ultrasonic Imaging
Jeong, Mok-Geun ; Song, Tae-Gyeong ; Park, Song-Bae ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 87~87
A new solution to the two-dimensional scalar wave equation is presented, which descries a diffraction-limited beam maintaining the lateral field response expressed by the sinc function. Physically, it is a superposition of plane waves having different wavelengths traveling in different directions. The beam can attain a line focus with one-dimensional array transducer in ultrasonic medial imaging.
The Implementation of Multi-Channel Audio Codec for Real-Time operation
Hong, Jin-Woo ;
The Journal of the Acoustical Society of Korea, volume 14, issue 2E, 1995, Pages 91~91
This paper describes the implementation of a multi-channel audio codec for HETV. This codec has the features of the 3/2-stereo plus low frequency enhancement, downward compatibility with the smaller number of channels, backward compatibility with the existing 2/0-stereo system(MPEG-1 audio), and multilingual capability. The encoder of this codec consists of 6-channel analog audio input part with the sampling rate of 48 kHz, 4-channel digital audio input part and three TMS320C40 /DSPs. The encoder implements multi-channel audio compression using a human perceptual psychoacoustic model, and has the bit rate reduction to 384 kbit/s without impairment of subjective quality. The decoder consists of 6-channel analog audio output part, 4-channel digital audio output part, and two TMS320C40 DSPs for a decoding procedure. The decoder analyzes the bit stream received with bit rate of 384 kbit/s from the encoder and reproduces the multi-channel audio signals for analog and digital outputs. The multi-processing of this audio codec using multiple DSPs is ensured by high speed transfer of date between DSPs through coordinating communication port activities with DMA coprocessors. Finally, some technical considerations are suggested to realize the problem of real-time operation, which are found out through the implementation of this codec using the MPEG-2 layer II sudio coding algorithm and the use of the hardware architecture with commercial multiple DSPs.