• Title/Summary/Keyword: and symmetry

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ON THE SYMMETRY PROPERTIES OF THE GENERALIZED HIGHER-ORDER EULER POLYNOMIALS

  • Bayad, Abdelmejid;Kim, Tae-Kyun;Choi, Jong-Sung;Kim, Young-Hee;Lee, Byung-Je
    • Journal of applied mathematics & informatics
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    • v.29 no.1_2
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    • pp.511-516
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    • 2011
  • In this paper we prove a generalized symmetry relation between the generalized Euler polynomials and the generalized higher-order (attached to Dirichlet character) Euler polynomials. Indeed, we prove a relation between the power sum polynomials and the generalized higher-order Euler polynomials..

Spin Transfer Torque in Ferromagnet-Normal Metal-Antiferromagnet Junctions

  • Lee, Hyun-Woo;Yang, Hyun-Soo
    • Journal of Magnetics
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    • v.16 no.2
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    • pp.92-96
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    • 2011
  • This study investigated theoretically the properties of the spin transfer torque acting on a ferromagnet in a ferromagnet-normal metal-antiferromagnet junction. Earlier work showed that the angular dependence of the spin transfer torque can be a wavy-type if the junction satisfies a special symmetry. This paper reports a simple model analysis that allows a derivation of the wavy angular dependence without taking advantage of the symmetry. This result suggests that the wavy angular dependence can appear even when the symmetry is broken. As an illustration, the angular dependence was calculated as a function of the degree of the compensation at the normal metal-antiferromagnet interface. The implications of the result for the current-induced magnetization precession are discussed.

Comparison of Various Turbulence Models for the Calculation of Plane of Symmetry Flows (대칭단면에서의 난류모형 비교)

  • 손창현;최도형;정명균
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.5
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    • pp.1052-1060
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    • 1989
  • Using a vortex stretching invariant term, the two-layer k-.epsilon. model has been modified to account for the extra staining of turbulence due to the mean-flow convergence and divergence. The calculations of turbulent boundary layers in a plane of symmetry are compared for experimental cases which are an axisymmetric body at an incidence of 15.deg.. The comparisons between the calculations and experimental data show that additional modifications to the dissipation rate equation have brought the significant improvement to the prediction of plane of symmetry boundary layers in the strong mean-flow convergence and divergence.

A Bilateral Symmetry Average Method for Robust Face Detection against Illumination Variation (조명 변화에 강인한 얼굴 검출을 위한 좌우대칭 평균화 기법)

  • Cho Chi-Young;Kim Soo-Hwang
    • Journal of Game and Entertainment
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    • v.2 no.2
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    • pp.45-50
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    • 2006
  • In a face detection system based on template matching, histogram equalization or log transform is applied to an input image for the intensity normalization and the image improvement. It is known that they are noneffective in improving an image with intensity distortion by illumination variation. In this paper, we propose an efficient image improvement method called as a bilateral symmetry average for images with intensity distortion by illumination variation. Experimental results show that our method delivers the detection performance better than previous methods and also remarkably reduces the number of face candidates.

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A Study on the Plane Figure of Elementary School Mathematics in the View of Classification (분류의 관점에서 초등수학 평면도형 고찰)

  • Kim, Hae Gyu;Lee, Hosoo;Choi, Keunbae
    • East Asian mathematical journal
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    • v.37 no.4
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    • pp.355-379
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    • 2021
  • In this article, we investigated plane figures introduced in elementary school mathematics in the perspective of traditional classification, and also analyzed plane figures focused on the invariance of plane figures out of traditional classification. In the view of traditional classification, how to treat trapezoids was a key argument. In the current mathematics curriculum of the elementary school mathematics, the concept of sliding, flipping, and turning are introduced as part of development activities of spatial sense, but it is rare to apply them directly to figures. For example, how are squares and rectangles different in terms of symmetry? One of the main purposes of geometry learning is the classification of figures. Thus, the activity of classifying plane figures from a symmetrical point of view has sufficiently educational significance from Klein's point of view.

Tunneling Characteristics in $Pb/Bi_2Sr_2CaCu_2O_{8+\delta}$ Junctions as an Evidence for a d-wave Order Parameter Symmetry in $Bi_2Sr_2CaCu_2O_{8+\delta}$ Superconductors ($Bi_2Sr_2CaCu_2O_{8+\delta}$ 고온초전도체의 d-파 대칭성 증거로서의 $Pb/Bi_2Sr_2CaCu_2O_{8+\delta}$접합 투과전도특성)

  • Chang, Hyun-Sik;Lee, Hu-Jong
    • Progress in Superconductivity
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    • v.2 no.2
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    • pp.65-70
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    • 2001
  • $Pb/Bi_2Sr_2CaCu_2O_{8+\delta}$-single-crystal junctions with the tunneling direction along the c axis of the crystal were fabricated to obtain an s-wave-superconductor/d-wave-superconductor Josephson junctions. The tunneling R (T) curves and current-voltage characteristics show distinct features which can be explained only under the assumption that the order parameter of high-$T_c/Bi_2Sr_2CaCu_2O_{8+{\delta}}$ superconductors has a pure d-wave symmetry, which is in contrast to the case of $YBa_2Cu_3O_{7+{\delta$}}$erconductors where a minor s-wave component is also present..

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Elastic Wave Propagation in Monoclinic System Due to Transient Line Load

  • Kim, Yong-Yun
    • The Journal of the Acoustical Society of Korea
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    • v.17 no.2E
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    • pp.53-58
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    • 1998
  • In this paper, we study the response of several anisotropic systems to buried transient line loads. The problem is mathematically formulated based on the equations of motion in the constitutive relations. The load is in form of a normal stress acting with arbitrary axis on the plane of monoclinic symmetry. Plane wave equation is coupled with vertical shear wave, longitudinal wave and horizontal shear wave. We first considered the equation of motion in reference coordinate system, where the line load is coincident with symmetry axis of the orthotrioic material. Then the equation of motion is transformed with respect to general coordiante system with azimuthal angle by using transformation tensor. The load is first described as a body force in the equations of the motion for the infinite media and then it is mathematically characterized. Subsequently the results for semi-infinite spaces is also obtained by using superposition of the infinite medium solution together with a scattered solution from the free surface. Consequently explicit solutions for the displacements are obtained by using Cargniard-DeHoop contour. Numerical results which are drawn from concrete examples of orthotropic material belonging to monoclinic symmetry are demonstrated.

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Applications of quantitative convergent beam electron diffraction measurement for structural characterization (Convergent beam electron diffraction의 정량분석을 응용한 재료의 구조분석)

  • Kim, Gyu-Hyeon;Lee, Min-Hui;Jeong, Sae-Eun;Go, Se-Hyeon
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2014.11a
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    • pp.176-177
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    • 2014
  • The new algorithm was proposed to quantify symmetry recorded in convergent beam electron diffraction (CBED) patterns and symmetry mapping. The proposed algorithm is based on the normalized cross-correlation coefficient (${\gamma}$) for quantifying the amount of symmetry in a CBED pattern. The quantification and mapping procedures are automatically controlled by the script implemented in Gatan Digital Micrograph$^{(c)}$. We apply the quantitative CBED measurement to a strained Si sample to test the sensitivity to defects.

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Polarized Raman Spectroscopic Studies of Syndiotactic Polypropylene (편광 Raman 분광법을 이용한 Syndiotactic Polypropylene에 관한 연구)

  • 진정희;임현주;김성수;송기국
    • Polymer(Korea)
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    • v.26 no.6
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    • pp.745-751
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    • 2002
  • The anisotropic Raman scattering properties of oriented syndiotactic poly propylene have been investigated using FT-Raman spectrometer in which the fluore scent problem of polymer samples can be removed. To assign the observed Raman bands to their respective symmetry species, the anisotropic scattering results for four different combinations of incident and scattered polarization were compared with those predicted by normal coordinate analysis and infrared dichroism measurement data.

An Algorithm for Detecting Gemetric Symmetry in a Plannar Graph (평면 그래프의 기하학적 대칭성 탐지 알고리즘)

  • Hong, Seok-Hui;Lee, Sang-Ho
    • Journal of KIISE:Computer Systems and Theory
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    • v.26 no.1
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    • pp.107-116
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    • 1999
  • 대칭성(symmetry)은 그래프의 구조와 특성을 시각적으로 표현할 때 중요한 미적 기준 중의 하나이다. 또한 대칭성을 보여주는 드로잉은 전체 그래프가 크기가 작은 부그래트들로부터 반복적으로 구성됨을 보여줌으로써 전체 그래프에 대한 이해를 쉽게 푸는 해주는 장점이 있다. 하지만 일반적인 그래프에서 기하하적 대칭성(geometric symmetry)을 탐지하는 문제는 이미 NP-complete 임이 증명되었으므로 이에 대한 연구는 평면 그래프(planar graph)의 극히 제한적인 부분집합인 트리, 외부 평면 그래프, 임베딩된 (embedded) 평면 그래프 등에 초점이 맞추어져 왔다. 본 논문에서는 평면 그래프에서의 기하학적 대칭성 문제를 연구하였다. 평면 그래프를 이중 연결 성분들로 분할한 다음 이를 각각 다시 삼중 연결 성분들로 분할하여 트리를 구성하고 축소(reduction)개념을 도입함으로써 기하학적 대칭성을 탐지하는 O(n2)시간 알고리즘을 제시하였다. 여기서 n은 그래프의 정점의 개수이다. 이 알고리즘은 평면 그래프를 최대한 대칭적으로 드로잉하는 알고리즘 개발에 이용될 수 있다.