• The Journal of the Acoustical Society of Korea
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• v.24 no.6
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• pp.325-333
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• 2005

This paper proposes a geoacoustic inversion method for the experimental data or MAPLE 2004 experiment conducted in the East Sea of Korea in 2004 and shows source tracking test results to validate the Proposed inversion method. An objective function is defined as a correlation function of the measured and the simulated transmission loss data. The measured transmission data were obtained using a multi-tonal towed source and VLA. The VFSA (Very Fast Simulated Annealing) is applied to the inversion Problem which optimizes the objective function. After performing the inversion process for the S frequencies tonal data independently. geoacoustic models are constructed. Finally matched-field source tracking is Performed using the inverted parameters to verify them.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.393-396
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• 2004

본 논문에서는 선박의 소음을 이용한 선박의 위치추적 및 지음향학적 인자의 역산 기법을 제안하였다. 예인 수평선배열에 의해 계측된 선박의 소음을 시간역전시켜(time reversed) 역전파(back propagation)시킨 음파는 해당 해양환경과 동일한 경우 원래의 음원 즉 선박의 위치에 가장 큰 에너지가 집중된다. 이러한 역전파된 신호의 집중 정도를 이용하여 음원의 위치 및 해양환경(특히 지음향학적 환경) 정보를 추정하였다. 본 역산에서 사용된 목적함수는 정합임펄스응답필터를 사용하여 음원의 위치에 집중된 정규화된 파워로 정의되었다. 최적화 알고리즘으로 유전알고리즘과 Powell 방법이 함께 사용되었다. 제안된 기법을 Elba섬 근해에서 실시된 MAPEX 2000 실험 데이터에 적용한 후 그 결과를 본 논문에서 제시하였으며 그 효용성을 확인하였다.

• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.308-316
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• 2013

A set of experiments (Shallow Water 2006, SW06) was carried out in shallow water near the New Jersey shelf break in summer 2006. Significant fluctuations in direct and surface reflected arrivals were observed from the chirp data (1100~2900 Hz) measured on a vertical line array. This paper presents a geoacoustic inverssion technique for short-range acoustic data with fluctuating arrivals and inversion results of experimental data. In order to reduce effects of random sea surface on the inversion, the acoustic energy back-propagated from the array to the source through direct and bottom-reflected paths is defined as the objective function. A multi-step inversion scheme is applied to the data using VFSR (Very Fast Simulated Reannealing) optimization technique. The inversion results show a source depth oscillation period equal to the measured ocean surface wave period. The inverted bottom sound speed is 1645 m/s and is similar to that estimated by other work at the same site.

• The Journal of the Acoustical Society of Korea
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• v.24 no.6
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• pp.334-342
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• 2005

In this Paper. a time-domain geoacoustic inversion was performed using the bulb signals measured during MがU. 04 experiment conducted in the East Sea of Korea in 2004. An obiective function was defined as a direct cross-correlation between the measured and the simulated signals in time domain. The ray theory was used to model the wave propagation in time domain and optimizations were Performed using VFSA (very fast simulated annealing) algorithm. Comparison of inversion results with those from transmission loss matching (an accompanying paper in this issue of the Journal of the Acoustical Society of Korea) shows that Parameters are consistently inverted. Direct time series comparisons between the measured signals and the simulated signals are Presented based on inversion results.

• 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.