• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.9
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• pp.14-22
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• 2015

TIn this paper, a centering method for an unfocused input character using the spherical domain system and the centering character to use the shift invariant feature for the recognition system is proposed. A system for recognition is implemented using the centroid method with coordinate average values, and the results of an above 78.14% average differential ratio for the character features were obtained. It is possible to extract the shift invariant feature using spherical transformation similar to the human eyeball. The proposed method, which is feature extraction using spherical coordinate transform and transformed extracted data, makes it possible to move the character to the center position of the input plane. Both digital and optical technologies are mixed using a spherical coordinate similar to the 3 dimensional human eyeball for the 2 dimensional plane format. In this paper, a centering character feature using the spherical domain is proposed for character recognition, and possibilities for the recognized possible character shape as well as calculating the differential ratio of the centered character using a centroid method are suggested.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.408-413
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• 2005

This paper presents a technique which extracts a moving object from omni-directional images and estimates a real coordinates of the moving object using 3D parabolic coordinate transformation. To process real-time, a moving object was extracted by proposed Hue histogram Matching Algorithms. We demonstrate our proposed technique could extract a moving object strongly without effects of light changing and estimate approximation values of real coordinates with theoretical and experimental arguments.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.19-22
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• 2002

A process of 3-D particle image velocimetry, called here, as '3-D stereo PIV' was developed for the measurement of a section field of 3-D complex flows. The present method includes modeling of camera by a calibrator based on the homogeneous coordinate system, transfromation of oblique-angled image to transformed image, identification of 2-D velocity vectors by 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system and finally 3-D animation as the post processing. In principle, as two frame images only are necessary for the single instantaneous analysis of a section field of 3-D flow, more effective vectors are obtainable contrary to the previous multi-frame vector algorithm. An experimental system was also used for the application of the proposed method. Three analog CCD cameras and an Argon-Ion Laser(300mW) for illumination were adopted to capture the wake flow behind a bluff obstacle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1757-1764
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• 1997

The geometric and elastic models based on the unit cell have been proposed to predict the geometric characteristics and the engineering constants of plain and satin woven composites. In the geometric model, length and inclined angle of the yarn crimp and the fiber volume fraction of woven composites have been predicted. In the elastic model, the coordinate transformation has been utilized to transform the elastic constants of the yarn crimp to those of woven composites, and the effective elastic constants have been determined from the volume averaging of the constituent materials. Good correlations between the model predictions and the experimental results of carbon/epoxy and glass/epoxy woven composites have been observed. Based on the model, the effect of various geometric parameters and materials on the three-dimensional elastic properties of woven composites can be identified.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.2 s.36
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• pp.33-42
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• 2006

Recently, the studies on the extraction of 3-dimension position information and attribute information of ground surface using LiDAR data. LiDAR data has high locational accuracy, and advantage that can process data more fast because there's not coordinate transform when acquire of Data justly the ground coordinate by Acquiring. The paper using only LiDAR data Manufacture road, building, contour That occupy a many parts of Digital Map. Estimated for possibility of Digital mapping using only LiDAR data As that compare accuracy with Digital map.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.9
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• pp.785-795
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• 1990

For the far field radiation pattern of a microstrip array antenna which is conformed to a cylindrical surface and forms an arc array, an approximate analysis method using FOURIER TRANSFORM is presented. In this method, the conformal array antenna is projected on the effective aperture plane and assumed to be an aperiodic array with nonlinear phase tilt. The effective aperture plane includes four end-points of each arc on the cylindrical surface. When the effective aperture ratio which is normalized to the planar type is from 1.0 to 0.9, it is confirmed that this approximate method is valid. To the array on the effective aperture plane, it is assumed that the phase tilt is due to the distance between aperture plne and curvature surface. Specially, when the radius of arc is more than 5 times to its length, the FOURIER TRANSFORM METHOD could be used with only varying scale factors. The results of calculating by approximate method are good agreement with the results of COORDINATE TRANSFORM METHOD and experimentally measured value in the range of -40dB. And, the difference of half power angle is less than 5 degrees when the effective aperture ratio moer than 0.9.

• Journal of Industrial Technology
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• v.25 no.B
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• pp.89-97
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• 2005

Application of proper orthogonal decomposition (POD) and continuous wavelet transform (CWT) is introduced to study wind speed and building roof pressures of flow separation region. In this study, a detailed analysis of the approach wind flow, wind-induced building pressure and the relation between the two fields was carried out using the POD technique and CWT analysis. The results show potential of the application of POD and CWT in characterization of spatio-temporal and spectral properties of the approach wind and its induced dynamic pressure events. Some of findings resulting from the application of this analysis can be summarized as follows: (1) The POD first principal coordinate of the roof pressure in the separated shear layer is closely correlated with the longitudinal component of oncoming flow. (2) The CWT analysis suggests that the extreme peak pressure in the separated shear layer is due to condensed large-scale eddy motions.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.4
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• pp.26-34
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• 2008

This article provides a comprehensive treatment of cracks in non-homogeneous structural materials such as functionally graded materials (FGMs). It is assumed that the material properties depend only on the coordinate perpendicular to the crack surfaces and vary continuously along the crack faces. By using laminated composite plate model to simulate the material non-homogeneity, we present an algorithm for solving the system based on Laplace transform and Fourier transform techniques. Unlike earlier studies that considered certain assumed property distributions and a single crack problem, the current investigation studies multiple crack problem in the FGMs with arbitrarily varying material properties. As a numerical illustration, transient thermal flow intensity factors for a metal-ceramic joint specimen with a functionally graded interlayer subjected to sudden heating on its boundary are presented. The results obtained demonstrate that the present model is an efficient tool in the fracture analysis of non-homogeneous material with properties varying in the thickness direction.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.1
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• pp.15-23
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• 2011

The purpose of this paper is to investigate the time behavior of a multiple crack problems. It is assumed that the medium contains cracks perpendicular to the crack surfaces, that the thermo-mechanical properties are continuous functions of the thickness coordinate. we use the laminated composite plate model to simulate the material non-homogeneity. By utilizing the Laplace transform and Fourier transform techniques, the multiple crack problems in the non-homogeneous medium is formulated. Singular integral equations are derived and solved to investigate the multiple crack problems. As a numerical illustration, transient thermal stress intensity factors(TSIFs) for a functionally graded material plate subjected to sudden heating on its boundary are provided. The variation in the TSIFs due to the change in material gradient and the crack position is studied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.227-232
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• 1995

This paper presents a digital modeling technique for the distributed parameter system. The basic idea of the proposed technique is to discretize a continuous system with respect to the spatial coordinate using the approximate methods such as bilinear method and backward difference method. The response of the discretized system is analyzed by Laplace transform and Z transform. The computational result of the proposed technique in a torsional shaft is compared with the exact solution and the result of the finite element method.