• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.694-699
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• 2011

A closed-form technique is presented for estimating a single source location from a set of noisy time delay measurements between distributed sensors. The localization formula is derived from nonlinear least squares minimization over the unknowns of target range and bearing in polar coordinates. Computer simulation results are provided for the purpose of performance analysis. Constrained least squares minimization method with prior source location information is also discussed.

• The Journal of the Acoustical Society of Korea
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• v.25 no.7
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• pp.346-355
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• 2006

Acoustic data from a shallow water experiment in the East Sea of Korea (MAPLE IV) is Processed to investigate the Performance of matched-field geo-acoustic inversion and source localization. The receiver array consists of two legs as in an L-shape. one vertical and the other horizontal lying on the seabed. Narrowband multi-tone CW source was towed along a slightly inclined bathymetry track. The matched-field geo-acoustic inversion includes comparisons between three processing techniques. all based on the Bartlett processor as; (1) the coherent processing of the data from the full array, (2) the incoherent Product of each output from both the horizontal and vertical arrays, and (3) the cross correlation between the horizontal and vertical arrays. as well as processing each array leg separately. To verify the inversion results. matched-field source localization for low level source signal components were performed using the same Processors used at the inversion stage.

• The Journal of the Acoustical Society of Korea
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• v.20 no.6
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• pp.75-81
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• 2001

In this paper we analyzed the localization error of near-field detection algorithm in the sea. The near-field detection algorithms using triangulation and wavefront curvature basically assume a signal in two dimension of bearing and range. But the assumption causes localization error because there is three dimension of bearing, range, and depth in the sea. Even through three dimensional effect is considered, the localization error is occurred if multipath propagation in the sea is ignored. To analyze the localization error in the sea, we simulate the near-field localization using acoustic propagation model and focused beamforming considering wavefront curvature. The simulation results indicate that localization error always occurs in the sea and the error varied with sound velocity profile, water depth, bottom slope, source range, etc.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9B
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• pp.1551-1562
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• 2000

In the using of FBG developed in home land, we designed and manufactured three types of FBG sound transducers the first in Korea. On FBG transducers manufactured we made an demonstrated on respective frequency response peculiarties in the water and analyzed the special characters. As the experimental result on frequency response peculiarities, we made t possible underwater acoustic detection on C type to maximum 18kHz, And for the purpose of realization on multi-point signal detection on wide scope in the water, in the using of WDM(Wavelength Division Multiplexing) method and passive band-pass filter system, established arrays system and succeeded in multi-point underwater acoustic signal detection to the frequency 1.3KHz out of the two B type FBG transducers. Additionally, it would be possible directivity detection for the objects of its source as the intensity of detection signal varies with the sound source's direction and angle. From now on we prepared a new moment on the practical used study on FBG hydrophone.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.161-164
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• 1995

실시간 ANC 이전에, 소음원으로부터 대상계를 거친 신호와 소음원신호가 오차계를 거친 신호를 측정함으로서 이론적인 한계성능을 파악하기 위한 지표를 제시하였다. 이 지표는 오차계를 통과한 신호를 입력으로, 대상계를 통과한 신호를 출력으로 하는 계의 선형화 정도를 나타내는 다중기여도함수와 흡사한 형태로 나타났다. 제한된 상황에서 ANC 성능을 최대화 하고자 할 때 이 지표는 레퍼런스와 부가음원의 위치 및 갯수 결정등 여러가지 파라메터 결정에 매우 유용하게 쓰일 수 있다고 생각된다.

• The Journal of the Acoustical Society of Korea
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• v.16 no.6
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• pp.100-105
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• 1997

To analyze the multipath propagation effects on the source bearing detection of HLA(Horizontal Line Array), the conversion mechanism of the multipath into the bearing is described, and the bearing is estimated from the multipath modeled with typical sound velocity structures of the East and the South Sea of Korea. The erroneous bearing is observed from the beamforming outputs simulated with the modeled multipath, and the erroneous phenomena are analyzed. In case of the East Sea, since the multipath propagation with a high receiving angle occurs due to strong inverse slope of the sound velocity structure, it is possible that the estimated source bearing is different from the real source bearing, and that the number of the source is misrecognized.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.144-145
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• 2005

In this study, we have developed the high resolution multichannel seismic data acquisition system and shallow marine seismic source. It is easy to operate our source system which utilizes piezoelectric transducer of high electrical power. According to water depth, survey condition and purpose, transducer number of source system can be easily changed in order to maximize field applicability. In the recording part, we used 24 bits and 8 channel high speed A/D board in order to achieve the improvement of data quality and the efficiency of data acquisition. The developed system was tested and varied with the data acquisition parameters such as source-receiver offset, and transducer number versus water depth for the field application.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.5
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• pp.109-116
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• 2010

In this paper, we propose a method for extracting predominant melody of polyphonic music based on harmonic structure. Since polyphonic music contains multiple sound sources, the process of melody detection consists of extraction of multiple fundamental frequencies and determination of predominant melody using those fundamental frequencies. Harmonic structure is an important feature parameter of monophonic signal that has spectral peaks at the integer multiples of its fundamental frequency. We extract all fundamental frequency candidates contained in the polyphonic signal by verifying the required condition of harmonic structure. Then, we combine those harmonic peaks corresponding to each extracted fundamental frequency and assign a rank to each after calculating its harmonic average energy. We finally run pitch tracking based on the rank of extracted fundamental frequency and continuity of fundamental frequency, and determine the predominant melody. We measure the performance of proposed method using ADC 2004 DB and 100 Korean pop songs in terms of MIREX 2005 evaluation metrics, and pitch accuracy of 90.42% is obtained.

• The Journal of the Acoustical Society of Korea
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• v.13 no.1E
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• pp.55-63
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• 1994

A decision-theretic concept is introduced to investigate whether targets of interest in array sensor systems are present at some steering direction or not. The solutions to this problem are described as a set of discrete numbers 0 or 1 corresponding to the direction under consideration. This coded number representation is transplanted in the optimisation technique based on the Hopfield neural network, which may provide an easy understanding of determining the direction of arrival (DOA) of sources. Difficulties encountered in using the conventional state schemes of Hopfield neural network models are addressed and their related issues are raised. To deal with them, an idea that a neuron that decreases more energy difference for its state change of 0 to 1can have higher priority in the order of state transition than others is introduced. This does not only lead to an new state update scheme but also opens a different story in comparison to previous work. To cast the perspectives of the proposed approach and illustrate its effectiveness in source direction finding in array sensor system. simulation results and related discussions are presented in this paper.

• The Journal of the Acoustical Society of Korea
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• v.21 no.5
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• pp.446-454
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• 2002

This paper presents the Doppler Scanning technique which enables us to detect the relative positions of moving distributed sources using Doppler frequency shift estimate when the moving source consists of distributed sources with different signature frequencies. Doppler frequency shifts of characteristic frequencies of machinery noise sources such as ship's generator and propeller, with tine along CPA (Closest Point of Approach of moving source) are unique, and can be functioned with respect to each source position. Therefore, this technique can be applied to estimate the relative geometrical positions between machinery noise sources. The Extended Kalman Filter (EKF) which has a high frequency resolution with high time resolution, is adopted for improving accuracy of Doppler frequency shift estimate geometric resolution of machinery positions since machinery noise sources show in general low frequency band characteristics with limited spacial distance. The performance of the technique is examined by the numerical simulations and is verified by the experiment using loudspeaker sources on the roof of the car.