• Title/Summary/Keyword: Jacobi

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Certain Characterization of Real Hypersurfaces of type A in a Nonflat Complex Space Form

  • Ki, U-Hang
    • Kyungpook Mathematical Journal
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    • v.61 no.1
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    • pp.181-190
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    • 2021
  • Let M be a real hypersurface with almost contact metric structure (ϕ, ��, η, g) in a nonflat complex space form Mn(c). We denote S and R�� by the Ricci tensor of M and by the structure Jacobi operator with respect to the vector field �� respectively. In this paper, we prove that M is a Hopf hypersurface of type A in Mn(c) if it satisfies R��ϕ = ϕR�� and at the same time R��(Sϕ - ϕS) = 0.

Exploration of an Optimal Two-Dimensional Multi-Core System for Singular Value Decomposition (특이치 분해를 위한 최적의 2차원 멀티코어 시스템 탐색)

  • Park, Yong-Hun;Kim, Cheol-Hong;Kim, Jong-Myon
    • Journal of the Korea Society of Computer and Information
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    • v.19 no.9
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    • pp.21-31
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    • 2014
  • Singular value decomposition (SVD) has been widely used to identify unique features from a data set in various fields. However, a complex matrix calculation of SVD requires tremendous computation time. This paper improves the performance of a representative one-sided block Jacoby algorithm using a two-dimensional (2D) multi-core system. In addition, this paper explores an optimal multi-core system by varying the number of processing elements in the 2D multi-core system with the same 400MHz clock frequency and TSMC 28nm technology for each matrix-based one-sided block Jacoby algorithm ($128{\times}128$, $64{\times}64$, $32{\times}32$, $16{\times}16$). Moreover, this paper demonstrates the potential of the 2D multi-core system for the one-sided block Jacoby algorithm by comparing the performance of the multi-core system with a commercial high-performance graphics processing unit (GPU).

F. H. Jacobi und Spinoza-Streit (야코비와 스피노자 논쟁)

  • Choi, Shin-Hann
    • Journal of Korean Philosophical Society
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    • v.129
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    • pp.315-339
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    • 2014
  • Diese Abhandlung untersucht Jacobis ${\ddot{U}}ber$ die Lehre Spinoza und den von diesem veranlassten Spinoza-Streit. Damit sie $enth{\ddot{u}}llt$ zuerst Jacobischen Zusammenhang zwischen transzent und immanent und folgt auf seine Wirkungsgeschichte in der Moderne. Ich rekonstruiere den Streit zwischen Jacobi und Lessing und danach interpretiere dessen Rezeption durch Hegel und Schleiermacher. Lessing stellt anstatt der traditionellen Begriffe der Gottheit ἑν ${\kappa}{\alpha}{\iota}$ ${\pi}{\alpha}{\nu}$ auf. $Demgegen{\ddot{u}}ber$ behauptet Jacobi Salto mortale um ihn ${\ddot{u}}berschreiten$ zu $k{\ddot{o}}nnen$, indem er Lessing als Pantheist und Atheist bestimmt. Salto mortale bei Jacobi ist der Sprung zu dem ${\ddot{U}}bernat{\ddot{u}}rlichen$ und dem Glaube. Der Streit zwischen Jacobi und Lessing ist der zwischen dem Naturalismus und ${\ddot{U}}bernaturalismus$ und $dar{\ddot{u}}berhinaus$ der zwischen dem Athismus und Theismus. $W{\ddot{a}}hrend$ die Natur der Inbegriff der Bedingten ist, ist Gott der absolute Anfang der Natur $au{\ss}erhalb$ des Naturzusammenhangs. $W{\ddot{a}}hrend$ Spinoza Gott im $nat{\ddot{u}}rlichen$ Zusammenhang begreift, $fa{\ss}t$ Jacobi den im ${\ddot{u}}bernat{\ddot{u}}rlichen$ auf. Deus sive natura bei Spinoza $ver{\ddot{a}}ndert$ sich Gott im Menschen bei Jacobi. Gott im Menschen ist nichts anders als das Prinzip des Lebens und das aller Vernuft. In diesem Zusammenhang $fa{\ss}t$ Hegel Gott als Geist denn Subjekt des Lebens auf und $h{\ddot{a}}lt$ das Wesen des Geistes $f{\ddot{u}}r$ die sich selbst vermittelnde Bewegung. Dies zeigt sich als die Spinoza ${\ddot{u}}berbietende$ Immanenzphilosophie. $Demgegen{\ddot{u}}ber$ behauptet Schleiermacher die Einheit des Endlichen und Unendlichen in der $religi{\ddot{o}}sen$ Anschuung. Die Verbindung von Mensch und Gott ist die im Endlichen immanent bleibende Anschauung der $g{\ddot{o}}ttlichen$ Eigenschaft. Dies zeigt das transzendente im immanenten.

Analysis of Radiation Characteristics of the Shaped Cassegrainian Antenna (수정곡면 카세그레인 안테나의 복사특성 해석)

  • Ryu, Hwang;Joo, Gi-Ho
    • The Journal of Engineering Research
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    • v.3 no.1
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    • pp.159-169
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    • 1998
  • The purpose of this study is to analyze the radiation characteristics of the shaped Cassegrainian antenna. Radiation pattern of the sub-reflector is calculated by GTD (Geometrical Theory of Diffraction) The complete radiation patterns are obtained by summing the reflect field from the surface and the diffracted fields from the edge. The first and the second derivative on the sub-reflector are calculated by the local interpolation technique. The Radiation characteristics of the main-reflector are obtained by integrating the surface current density, which is derived from PO approximation. The radiation integral is expanded by the Jacobi-Bessel series for the purpose of reducing the computation time.

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SEMI-INVARIANT SUBMANIFOLDS OF CODIMENSION 3 IN A COMPLEX SPACE FORM WITH 𝜉-PARALLEL STRUCTURE JACOBI OPERATOR

  • U-Hang KI;Hyunjung SONG
    • East Asian mathematical journal
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    • v.40 no.1
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    • pp.1-23
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    • 2024
  • Let M be a semi-invariant submanifold of codimension 3 with almost contact metric structure (𝜙, 𝜉, 𝜂, g) in a complex space form Mn+1(c). We denote by A, K and L the second fundamental forms with respect to the unit normal vector C, D and E respectively, where C is the distinguished normal vector, and by R𝜉 = R(𝜉, ·)𝜉 the structure Jacobi operator. Suppose that the third fundamental form t satisfies dt(X, Y) = 2𝜃g(𝜙X, Y) for a scalar 𝜃(≠ 2c) and any vector fields X and Y , and at the same time R𝜉K = KR𝜉 and ∇𝜙𝜉𝜉R𝜉 = 0. In this paper, we prove that if it satisfies ∇𝜉R𝜉 = 0 on M, then M is a real hypersurface of type (A) in Mn(c) provided that the scalar curvature $\bar{r}$ of M holds $\bar{r}-2(n-1)c{\leq}0$.