• Title/Summary/Keyword: Geometrical transformation

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The Geometrical Mode Analysis of an Elastically Suspended Rigid Body with Planes of Symmetry (대칭면을 갖는 강체 진동계의 진동모드에 대한 기하학적 해석)

  • Dan, Byeong-Ju;Choe, Yong-Je
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.1 s.173
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    • pp.110-117
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    • 2000
  • Vibration modes obtained from a modal analysis can be better explained from a screw theoretical standpoint. A vibration mode can be geometrically interpreted as a pure rotation about the vibration center in a plane and as the twisting motion on a screw in a three dimensional space. This paper, presents the method to diagonalize a spatial stiffness matrix by use of a parallel axis congruence transformation. It also describes that the stiffness matrix diagonalized by a congruence transformation, can have the planes of symmetry depending on the location of the center of elasticity. For a plane of symmetry, any vibration mode can be expressed by the axis of vibration. Analytical solutions for the axis of vibration has been derived.

Geometrical Defect Detection of Secondary Battery Using 3-Dimensional CAD Model (3D CAD 모델을 이용한 이차 전지의 형상 결함 검출)

  • Yeong-Ho Jo;Keun-Ho Rew;Sang-Yul Lee
    • Journal of Information Technology Applications and Management
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    • v.29 no.6
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    • pp.135-144
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    • 2022
  • In this study, we transformed 4680 type lithium-ion batteries to 3-dimensional CAD models and present a methodology to detect defects using Radon inverse transformation. Transparency was applied to the model to make it look like a CT image when viewed from the front. One normal and three defect models were created and analyzed. The models were saved as image files while rotating at a certain angle. Then, we used the Radon inverse transformation to reconstruct the original 3D geometry from the image files. Finally, we successfully found defects in the defect models for three cases.

Morphological Transformation of Building Blocks of Apartment Complexes in Busan (부산 아파트 단지의 주동 평면형태의 변화 특성에 관한 연구)

  • Lee, Sangjin;Park, SoHyun
    • Journal of the Architectural Institute of Korea Planning & Design
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    • v.35 no.8
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    • pp.3-14
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    • 2019
  • The research is to track the morphological transformation of residential towers of apartment complexes in Busan. Though apartment is one of the most important components in Korean society, it has not drawn enough attention from academia as well as the public, especially regarding its shape. In result, its morphological change has barely been recognized. Instead, negative, but superficial, evaluation has become dominant tendency to deal with the shape of apartment tower. There are numerous 'partial' evidences to inform the morphological change of apartment plan type, and understanding the change is critical since morphological resultant reflects culture, politics, economy of a society. The research has been done on the 261 apartment complexes built through 2016 in Busan. The analysis shows that $I^0$ type, to represent 'typical boring architectural shape' of Korean apartments, has been dominant until the year 2000. However, its portion has become drastically decreased since the mid-2000. Composite plan type, the geometrical precedents of which had never been existent, emerged in the mid-2000, and this phenomenon may symbolize the change of morphology of apartment. When tower plan types are grouped together according to geometrical shape, three types, I-type, L-type and Y-type, take the most of residential towers, explaining 97% of the total. As expected, I-type is the most dominant, but its influence has decreased as time passes. Y-type might become one of the most important type in the period V. L-type has become the leading type in the Period VI to exceed I-type by 12 percent.

Watermarking Algorithm that is Adaptive on Geometric Distortion in consequence of Restoration Pattern Matching (복구패턴 정합을 통한 기하학적 왜곡에 적응적인 워터마킹)

  • Jun Young-Min;Ko Il-Ju;Kim Dongho
    • The KIPS Transactions:PartB
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    • v.12B no.3 s.99
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    • pp.283-290
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    • 2005
  • The mismatched allocation of watermarking position due to parallel translation, rotation, and scaling distortion is a problem that requires an answer in watermarking. In this paper, we propose a watermarking method robust enough to hold against geometrical distorting using restoration pattern matching. The proposed method defines restoration pattern, then inserts the pattern to a watermark embedded image for distribution. Geometrical distortion is verified by comparing restoration pattern extracted from distributed image and the original restoration pattern inserted to the image. If geometrical distortion is found, inverse transformation is equally performed to synchronize the watermark insertion and extraction position. To evaluate the performance of the proposed method, experiments in translation, rotation, and scaling attack are performed.

대수체계의 발견에 관한 수학사적 고제

  • 한재영
    • Journal for History of Mathematics
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    • v.15 no.3
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    • pp.17-24
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    • 2002
  • It will be described the discovery of fundamental algebras such as complex numbers and the quaternions. Cardano(1539) was the first to introduce special types of complex numbers such as 5$\pm$$\sqrt{-15}$. Girald called the number a$\pm$$\sqrt{-b}$ solutions impossible. The term imaginary numbers was introduced by Descartes(1629) in “Discours la methode, La geometrie.” Euler knew the geometrical representation of complex numbers by points in a plane. Geometrical definitions of the addition and multiplication of complex numbers conceiving as directed line segments in a plane were given by Gauss in 1831. The expression “complex numbers” seems to be Gauss. Hamilton(1843) defined the complex numbers as paire of real numbers subject to conventional rules of addition and multiplication. Cauchy(1874) interpreted the complex numbers as residue classes of polynomials in R[x] modulo $x^2$+1. Sophus Lie(1880) introduced commutators [a, b] by the way expressing infinitesimal transformation as differential operations. In this paper, it will be studied general quaternion algebras to finding of algebraic structure in Algebras.

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A New Digital Watermarking for Architectural Design Drawing Using LINES and ARCs Based on Vertex (건축설계도면상에서 꼭지점에 기반한 LINE과 ARC를 이용한 디지털 워터마킹)

  • Jang, Bong-Ju;Moon, Kwang-Seok;Young Huh;Kwon, Ki-Ryong
    • Proceedings of the IEEK Conference
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    • 2003.11b
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    • pp.247-250
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    • 2003
  • This paper proposed to digital watermarking technique for architectural drawing using LINES and ARCs based on vertex in CAD system to prevent infringement of copyright from unlawfulness reproductions and distribution. After extract LINES and ARCs from designed drawing, we embed watermarks using adaptive algorithm in each characteristics. Watermarks robust to various attacks like as geometrical transformation as being embedded in LINE's length and ARC's angle information. Also, the proposed method satisfies enough transparency about watermarked drawing because have suitable embedding strength to each component. By experimental result, we confirmed robustness and invisibility of embedded watermarks in several conversions of architectural design drawing.

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Adaptive Digital Watermarking for Copyright Protection of CAD Data

  • Kwon Ki-Ryong;Koo Bon-Ho;Kim Ji-Hong
    • Journal of Korea Multimedia Society
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    • v.9 no.6
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    • pp.709-719
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    • 2006
  • To protect against unlawful reproductions and distribution, the current paper proposes a digital watermarking technique for architectural drawings produced using a CAD system. First, the POLYLINEs are extracted from the drawing; then, an adaptive algorithm is used to embed a watermark in the characteristics of each POLYLINE. Next, the CIRCLEs are embedded using an adaptive watermarking algorithm related to the radius of circle from drawing. The proposed watermarking scheme is robust to various attacks, such as the geometrical transformation. Additionally, the proposed method satisfies the requirement of transparency for CAD program. It used AutoCAD 2002, which is commonly used as a CAD program for experiments. Experimental results confirmed the robustness and invisibility of the embedded watermarks in several conversions of an architectural drawing.

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Correction of Ocular Fundus Fluorescein Angiogram in Nonlinear Distortion (비선형왜곡된 형광안저화상의 보정)

  • 고창림
    • Journal of Biomedical Engineering Research
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    • v.11 no.1
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    • pp.31-38
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    • 1990
  • Image correction of the fluorescein angiogram with the low contrast and geometrically distorted is studied. The procedure is divided into two steps : A template matching step and a geometrical transformation step. Based on the sequential similiarity detection algorithm, more Improved matching results are obtained with edge enhanced image. For the reference points and the corresponding matchimg points, the geometrical transformationss by the use of the average value of the X, Y translational shifts and a pair of these points, respectively are described. Then the corrected images are obtained using bilinear interpolation. It is proven that the usefullness of this study for the image correction of the ocular fundus fluoresceln angiogram with low contrast and geometrically distorted mainly due to the eye movements.

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Nonlinear free vibration analysis of moderately thick viscoelastic plates with various geometrical properties

  • Nasrin Jafari;Mojtaba Azhari
    • Steel and Composite Structures
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    • v.48 no.3
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    • pp.293-303
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    • 2023
  • In this paper, geometrically nonlinear free vibration analysis of Mindlin viscoelastic plates with various geometrical and material properties is studied based on the Von-Karman assumptions. A novel solution is proposed in which the nonlinear frequencies of time-dependent plates are predicted according to the nonlinear frequencies of plates not dependent on time. This method greatly reduces the cost of calculations. The viscoelastic properties obey the Boltzmann integral law with constant bulk modulus. The SHPC meshfree method is employed for spatial discretization. The Laplace transformation is used to convert equations from the time domain to the Laplace domain and vice versa. Solving the nonlinear complex eigenvalue problem in the Laplace-Carson domain numerically, the nonlinear frequencies, the nonlinear viscous damping frequencies, and the nonlinear damping ratios are verified and calculated for rectangular, skew, trapezoidal and circular plates with different boundary conditions and different material properties.

AUTOMATED DETECTION OF MICROCALCIFICATIONS ON MAMMOGRAM WITH MORPHLOGICAL FILTER

  • Jin, Hua-Rong;Kobatake, Hidefumi
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10b
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    • pp.1752-1757
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    • 1991
  • This paper presents a new method for detecting microcalcifications on mammograms by using morphological filter. This filter is an extension of Top-hat transformation in morphological operations with multi-scale and multiple structuring elements. The proposed method makes it possible to detect geometrical structures considered to be microcalcifications on the basis of their size, shape and density. Experimental results to show the effectiveness of the proposed method are also presented.

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