• Title/Summary/Keyword: 회전변형

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Texture Coding in MPEG-4 Using Modified Boundary Block Merging Technique (변형된 경제 블록 병합 기법을 이용한 MPEG-4의 텍스처 부호화)

  • 김두석;고형화
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.4B
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    • pp.725-733
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    • 2000
  • In this paper, we propose a modified boundary block merging technique for the texture coding of MPEG-4. We propose an ORP(Optimized Region Partitioning) method that partition the VOP-based reference position to minimize the number of coding blocks. The merging possibility is improved by adding +90。and -90。 Rotation merging. We propose a MRM(Multiple Rotation Merging) method which applies the rotation merging in the order of 180。, +90。and -90。. If a pair of boundary blocks has low correlation, existing BBM's padding technique is not efficient. Our padding after merging method gives better result even if it has low correlation. The proposed method showed 5 ~8(%) coding bit reduction at the same PSNR values compared to BBM method.

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Rotation invariant face recognition in a polar coordinate system using LDAr (극좌표계에서 회전에 강인한 LDAr을 이용한 얼굴 인식)

  • Oh, Jae-Hyun;Kwak, No-Jun
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2010.07a
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    • pp.195-197
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    • 2010
  • 본 논문은 기존 평행좌표를 이용하는 얼굴 영상 대신 극좌표계 변환을 이용한 얼굴 영상을 이용하여 회전에 강인한 얼굴인식 방법을 제안한다. 극좌표계 변환 방법은 얼굴의 중심부분의 한 점을 극으로 삼아 이 점을 기준으로 360도 각 방향으로 일정 길이만큼 얼굴 영상을 샘플링 하여 새로운 얼굴 영상을 제작하는 방법이다. 이 극좌표계 변환 방법을 이용해 재구성된 영상에 대해 회귀( regression )문제 해결을 위해 변형된 LDA인 LDAr(LDA for regression)을 이용하여 얼굴의 중심부분의한 점인 극을 중심으로 임의의 각도로 회전된 영상의 회전 정도를 추정하여 이를 정규화 시키는 방법을 통해 얼굴 인식의 인식률을 향상시키고자 한다. LDAr은 LDA의 기본개념인 각 클래스 간 떨어진 정도를 최대화하는 것이 목적으로 클래스간 분산과 클래스내 분산의 비율을 최대화 하는 방법을 응용하여 이를 회귀문제에 적용할 수 있게 변형을 한 것이다. 즉, LDAr은 목표값(target)의 차이가 큰 샘플들과 목표값의 차이가 작은 샘플들 간의 거리의 비율을 최대화 하는 것을 목적으로 하게 된다. 제안된 방법을 Yale데이터에 적용하여 임의의 각도로 회전시킨 영상에 대해 회전 각도를 정확히 찾아내는 것을 확인할 수 있었다.

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Ultimate Strength of branch-rotated T-joints in Cold-formed Square Hollow Sections - Chord flange failure mode - (지관이 회전된 냉간성형 각형강관 T형 접합부의 최대내력(I) - 주관 플랜지 파괴모드 -)

  • Bae, Kyu Woong;Park, Keum Sung;Kang, Chang Hoon;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.14 no.5 s.60
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    • pp.657-664
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    • 2002
  • This paper described the ultimate strength and deformation limit of the new uniplanar T-joints in cold-formed square hollow sections. In the configuration of the new T-joint, only a branch member is orientated to a chord member at 45 degrees in the plane of the truss. This study focused on the branch-rotated T-joints that were governed by chord flange failure in previous studies. Test results of the T-joint in cold-formed square hollow sections revealed a deformation limit of 3%B for $16.7{\leq}2{\gamma}(=B/T){\leq}33.3$ and $0.27{\leq}{\beta}(=b1/B){\leq}0.6$. The existing strength formulae for traditional T-joint were determined and a new yield-line model for the branch-rotated T-joint proposed. Finally, the strength formula on the yield-line analysis was compared with test results and the application range of the proposed formula recommended.

Dynamic Characteristics of Thick Rotating Composite Disks (두꺼운 복합재료 회전원판의 동적 특성)

  • Koo, Kyo-Nam
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.8
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    • pp.649-656
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    • 2016
  • Thick composite disks are utilized in the fast-rotating machines such as turbine disks, flywheels, and so on. The effects of rotating speed on the dynamic characteristics of thick composite disks are deeply studied in this paper. The dynamic governing equations of a rotating composite disk including transverse shear and rotary inertia are derived and then formulated into the finite element equation. Isotropic, circumferentially reinforced disk, and radially reinforced disk are selected for the numerical analysis. The inclusion of the transverse shear and rotary inertia into the governing equation of the rotating disks makes the natural frequency reduced as well as the critical speed. The present results show that the rotation of a thick disk may not reduce the effect of transverse shear and rotary inertia depending on anisotropy, thickness ratio and mode, unlike the results reported in other studies.

Correction of Rotated Objects in Medical Images Using the Mojette Transform (모젯 변환을 이용한 의료 영상의 회전 물체 보정)

  • Jung, Hyang-Mi;Kim, Ji-Hong
    • Journal of Korea Multimedia Society
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    • v.15 no.11
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    • pp.1341-1348
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    • 2012
  • In this paper, an efficient scheme for correcting rotated objects in medical images using the Mojette transform is presented. The Mojette transform is a kind of discrete Radon transform, where the transform domain is represented by a set of projections. The Mojette transform currently studied in the image compression area is modified for detecting the rotation angle of objects in medical images. First, in order to find accurate rotation angle, the projection value in the Mojette transform is determined by using pixels on the projection line and in addition the linear interpolation of pixels adjacent to the line. Second, at each projection angle, only one projection is implemented for reducing the amount of the calculation in the process of the Mojette transform. Finally, the projection in the Mojette transform is carried out at the predetermined ROI(Region Of Interest) at which the objects are not cropped or added by rotating the image. The simulation results show that the proposed method has good performance for correcting the rotation angle in medical images.

Nonlinear Analysis of Stress-strain for RC Panel Subjected to Shear (순수전단이 작용하는 RC Panel의 응력-변형률 비선형해석)

  • Cha, Young-Gyu;Kim, Hak-Su
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.14 no.1
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    • pp.175-181
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    • 2010
  • The three truss models(equilibrium truss model, Mohr compatibility truss model, and the soften truss model) based on a rotating angle is called the rotating-angle model. The three rotating-angle models have a common weakness: they are incapable of predicting the so-called "contribution of concrete". To take into account this "contribution of concrete", the modern truss model(MCFT, STM) treats a cracked reinforced concrete element as a continuous material. By combining the equilibrium, compatibility, and the softened stress-strain relationship of concrete in biaxial state, MTM is capable of producing the nonlinear analysis of reinforced concrete structures composed of membrane element. In this paper, an efficient algorithm is proposed for the solution of proposed model incorporated with failure criteria. This algorithm is used to analyze the behavior of reinforced membrane element using the results of Hsu test.

Shape Description and Recognition Using the Relative Distance-Curvature Feature Space (상대거리-곡률 특징 공간을 이용한 형태 기술 및 인식)

  • Kim Min-Ki
    • The KIPS Transactions:PartB
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    • v.12B no.5 s.101
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    • pp.527-534
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    • 2005
  • Rotation and scale variations make it difficult to solve the problem of shape description and recognition because these variations change the location of points composing the shape. However, some geometric Invariant points and the relations among them are not changed by these variations. Therefore, if points in image space depicted with the r-y coordinates system can be transformed into a new coordinates system that are invariant to rotation and scale, the problem of shape description and recognition becomes easier. This paper presents a shape description method via transformation from the image space into the invariant feature space having two axes: representing relative distance from a centroid and contour segment curvature(CSC). The relative distance describes how far a point departs from the centroid, and the CSC represents the degree of fluctuation in a contour segment. After transformation, mesh features were used to describe the shape mapped onto the feature space. Experimental results show that the proposed method is robust to rotation and scale variations.

A Four-node General Shell Element with Drilling DOFs (면내회전자유도를 갖는 4절점 곡면 쉘요소)

  • Chung, Keun-Young;Kim, Jae-Min;Lee, Eun-Haeng
    • Journal of the Earthquake Engineering Society of Korea
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    • v.16 no.4
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    • pp.37-52
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    • 2012
  • In this study, a new 4-node general shell element with 6 DOFs per node is presented. Drilling rotational degrees of freedom are introduced by the variational principle with an independent rotation field. In formulation of the element, substitute transverse shear strain fields are used to avoid shear locking, while four nonconforming modes are applied in the in-plane displacement fields as a remedy for membrane locking. In addition, a direct modification method for nonconforming modes is employed in the numerical implementation of nonconforming modes to represent constant strain states. A 9-points integration rule is adopted for volume integration in the computation of the element stiffness matrix. With the combined use of these techniques, the developed shell element has no spurious zero energy modes, and can represent a constant strain state. Several numerical tests are carried out to evaluate the performance of the new element developed. The test results show that the behavior of the elements is satisfactory.

Free Vibration of Stepped Horizontally Curved Members Supported by Two-Parameter Elastic Foundation (두 변수 탄성지반으로 지지된 불연속 변단면 수평 곡선부재의 자유진동)

  • Lee, Byoung Koo;Lee, Tae Eun;Ahn, Dae Soon;Kim, Mu Young
    • Journal of Korean Society of Steel Construction
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    • v.13 no.6
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    • pp.651-659
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    • 2001
  • The main purpose of this paper is to present an analytical method for free vibration of stepped horizontally curved members on two-parameter elastic foundation. The ordinary differential equations governing the free vibration of such beams are derived as non-dimensional forms including the effects of rotatory inertia and shear deformation. The governing equations are solved numerically for the circular, parabolic, sinusoidal and elliptic curved beams with hinged-hinged, hinged-clamped and clamped-clamped end constraints. As the numerical results, the lowest four natural frequency parameters are presented as the functions of various non-dimensional system parameters. Also the typical mode shapes are presented.

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