• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.389-392
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• 2004

정합장처리를 이용한 표적의 탐지는 다양한 종류의 간섭표적들이 존재하는 환경에서 수행될 가능성이 크며, 따라서 분해능이 높은 적응 정합장처리를 사용이 요구된다. 반면 빠르게 움직이는 고소음의 간섭표적이 존재 할 경우에는 적응정합장처리를 수행하기위한 신호단편 (snapshot) 수를 충분하게 사용할 수 없는 상황에 직면하게 된다. 제한된 신호단편을 이용하여 적응정합장처리의 CSDM (cross-spectral density matrix)을 안정적으로 추정하기 위한 목적으로 선형빔형성에서 제안되었던 광대역 STMV (steered minimum varianve) 기법을 도입하였다. MAPLE03 실험환경을 이용하여 STMV의 적응정합장처리 수치실험을 수행하고 특성을 분석하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.210-213
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• 1999

수동소나체계에서 음원의 위치와 관련된 매개변수를 산출하기 위해 정합장처리(Matched Field Processing)가 이용된다 본 연구에서는 수직선배열센서를 이용한 정합장처리에서 음원 위치추정에 영향을 미치는 다양한 요인 중, 수직음속분포 오정합(mismatch)에 의한 영향을 MV 프로세서 (Minimum Variance Processor)를 이용하여 모의실험함으로써 그 결과를 분석하였다. 천해 모의환경에서 동일한 기울기로 증감하는 수직음속분포 오정합은 음원 위치추정에서 거리성분의 오차를 가지며, 상이한 기울기를 갖는 수직음속분포 오정합은 거리와 수심 성분의 오차가 유발됨을 확인할 수 있었다. 심해 모의 환경에서 수직음속분포 오정합은 거리와 수심 성분의 오차가 유발되고, 거리추정의 전반적인 경향은 천해의 동일한 기울기를 가지는 경우와 유사함을 확인할 수 있었다.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.501-506
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• 2000

Many research in Robot control has effectively proceeded on the development of Aritficial Intelligence Robot which is able to apply to the uncertain and monotonous operations which are repeated continuously in the industrial field. In this study, the precise shape recognition of base metal for welding was gained by mono CCD camera, and the gained data was transformed into Decimal code through Image Board in computer. And the Fuzzy Logic control system designed by use of Fuzzy rule was built to judge whether the base metals were precisely matched or not with Decimal code. Machanically manipulated Robot syst em was linked to Fuzzy Control system through image information, and ultimately, these systems will be able to apply for production system.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.339-343
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• 2001

본 연구에서는 수중 음의 전달에 작용하는 기하와 지음향 매개변수들을 전역 최적화(global optimization) 방법인 유전자 알고리듬을 사용하여 추정하려한다. 유전자 알고리듬은 목적함수가 불규칙적인 경우에도 모든 가능한 매개변수들을 조사하지 않으면서 전역 최대치 또는 최소치를 추정할 수 있는 최적화 방법으로, 정합장처리와 관련된 매개변수의 조사에 적합한 방향성 조사법이라 할 수 있다. 유전자 알고리듬을 이용하여 천해 해양환경에서 수치실험을 통해 매개변수 역산의 가능성을 살펴보도록 하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.97-100
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• 2000

정합장처리(matched-field processing)는 실제 음향자료와 복제음장과의 공간 coherence를 이용한 음장의 역추정 방법이다. 광대역 스펙트럼을 가지는 음원의 경우 협대역 단일 주파수별로 정합장 출력을 계산한 후, 각 출력을 더하는 incoherent 광대역 정합장처리를 사용하였으나, 그 경우 수신기들과 주파수들간의 상호 공간과 주파수 정보를 사용치 못하므로 음원 위치추정 성능이 저하된다. 본 논문에서는 광대역 스펙트럼의 여러 주파수를 사용하여 확장된 CSDM(cross-spectral density matrix)을 구성하여 coherent 정합장처리를 구현하고, 각 정합장처리 기법에 대한 음원 위치추정 성능을 분석하였다.

• The Journal of Engineering Geology
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• v.7 no.1
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• pp.27-36
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• 1997

This paper shows that crosshole seismic survey allows to detect even a small size of underground tunnel (about 2m$\times$2m). Such a small tunnel (e.g. infiltration tunnel) causes diffraction, as the seismic wave propagates, which results in distinctive variations of traveltime and amplitude of the first arrivals. This effect (or tunnel effect) is a typical indicator for the existence of tunnel and thereby an information about the tunnel location can be obtained. It was shown that the tunnel effect illustrated by numerical modeling (FDM) could be also observed in field measurements. The depth and shape of the tunnel were determined by a simplified processing method based on the use of amplitude variation of the first arrivals. The estimated location of the tunnel was well matched to that of the real tunnel.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.1
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• pp.43-57
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• 2002

This paper introduces an analysis method to predicting the flow characteristic of flow field around otter board In order to develope a high performance model. In this experiment, it is used a numerical analysis of flow field through CFD(Computational Fluid Dynamic), PIV method in which quantitative, qualitative evaluation is possible. In this experiment, it is used PIV method with flow filed image around otter board in order to analysis of flow characteristic. The result compared flow pattern with analysis result through CFD and also measurement result of lift and drag force coefficient carried out in CWC(Circulating Water Channel). The numerical analysis result is matched well with experiment result of PIV in the research and it is able to verify In the physical aspect. The result is as follows ; (1) It was carried out visibility experiment using laser light sheet, and picture analysis through PIV method in order to analysis fluid field of otter-board. As a result, the tendency of qualitative fluid movement only through the fluid particle's flow could be known. (2) Since PIV analysis result is quantitative, this can be seen in velocity vector distributions, instantaneous streamline contour, and average vorticity distributions through various post processing method. As a result, the change of flow field could be confirmed. (3) At angle of attack 24$^{\circ}$ where It Is shown maximum spreading force coefficient, the analysis result of CFD and PIV had very similar flow pattern. In both case, at the otter-board post edge a little boundary layer separation was seen, but, generally they had a good flow (4) As the result of post processing with velocity vector distributions, instantaneous streamline contour and average vorticity distributions by PIV, boundary layer separation phenomenon started to happen from angle of attack 24$^{\circ}$, and from over angle of attack 28$^{\circ}$, it happen at leading edge side with the width enlarged.

• Journal of Environmental Science International
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• v.21 no.6
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• pp.739-747
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• 2012

Due to the difficulties for measuring flood discharge in the dangerous field conditions, conventional instruments with relatively low accuracy such as float still have been widely utilized for the field survey. It is also limited to use simple stage-discharge relationship for assessment of the flood discharge, since the stage-discharge relationship during the flood becomes complicated loop shape. In recent years, various non-intrusive velocity measurement techniques such as electromagnetic wave or surface images have been developed, which is quite adequate for the flood discharge measurements. However, these new non-intrusive techniques have little tested in the flood condition, though they promised efficiency and accuracy. Throughout the field observations, we evaluated the validity of these techniques by comparing discharge and velocity measurements acquired concurrently during the flood in a mountain stream. As a result, the flood discharge measurements between electromagnetic wave and surface image processing techniques showed high positive relationship, but velocities did not matched very well particularly for the high current speed more 3 m/s. Therefore, it should be noted here that special cares are required when the velocity measurements by those two different techniques are used, for instance, for the validation of the numerical models. In addition, authors assured that, for the more accurate flood discharge measurements, velocity observation as well as stage height is strongly necessary owing that the unsteady flow occurs during the flood.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.5
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• pp.311-317
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• 2015

The aim of this study is to develop a 3D registration algorithm for positron emission tomography/computed tomography (PET/CT) and magnetic resonance (MR) images acquired from independent PET/CT and MR imaging systems. Combined PET/CT images provide anatomic and functional information, and MR images have high resolution for soft tissue. With the registration technique, the strengths of each modality image can be combined to achieve higher performance in diagnosis and radiotherapy planning. The proposed method consists of two stages: normalized mutual information (NMI)-based global matching and independent component analysis (ICA)-based refinement. In global matching, the field of view of the CT and MR images are adjusted to the same size in the preprocessing step. Then, the target image is geometrically transformed, and the similarities between the two images are measured with NMI. The optimization step updates the transformation parameters to efficiently find the best matched parameter set. In the refinement stage, ICA planes from the windowed image slices are extracted and the similarity between the images is measured to determine the transformation parameters of the control points. B-spline. based freeform deformation is performed for the geometric transformation. The results show good agreement between PET/CT and MR images.

• The Journal of the Acoustical Society of Korea
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• v.20 no.7
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• pp.94-100
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• 2001

When using a sample covariance matrix data in paucity of snapshots, adaptive matched field processing will have problem in inverting covariance matrix due to the rank deficiency. The general solutions are diagonal loading and eigenanalysis methods, but there is a significant bias in the power output. This paper presents a quantitative study of bias of power output and the performance of source localization through the simulation and the measured data analysis in fixed source case using the diagonal loading method for the minimum variance processor. Results show that the bias in power output is reduced and the performance of source localization is improved when the number of snapshots is greater than the number of array sensors.