• 호남수학학술지
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• 제29권3호
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• pp.481-493
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• 2007

We will construct several types of semi-regular tilings of a hyperbolic unit disk model by defining geometric features of the definition of distance in a hyperbolic plane, area of triangle, and isometry of inversions. We researched the method of regular tilings and semi-regular tilings of hyperbolic unit disk model and wrote an semi-regular tiling construction algorithm using Cabri2 program and Cinderella program. Lastly, We want to make a product related to traditional heritage cultural patterns using Photoshop, so we'll model the advertising photos of cites; Seoul, Gwangju.

• 대한수학회논문집
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• 제9권4호
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• pp.783-796
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• 1994

Let V be a vector space of dimension m over Q, and let (, ) be a non-degenerate bilinear form on V. Let r be the Witt index of V, and let $V = V' + V_0 + V"$ be the Witt decomposition, where $V_0$ is anisotropic and V', V" are paired non-singularly. Let H = O(m-r, r) be the isometry group of V, (, ), viewed as an algebraic group over Q. Let G = Sp(n) be the symplectic group of rank n defined over Q.ed over Q.

• 대한수학회지
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• 제41권1호
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• pp.145-156
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• 2004

Let $D_1,\;D_2$ be convex domains in complex normed spaces $E_1,\;E_2$ respectively. When a mapping $f\;:\;D_1{\rightarrow}D_2$ is holomorphic with f(0) = 0, we obtain some results like the Schwarz lemma. Furthermore, we discuss a condition whereby f is linear or injective or isometry.

• 충청수학회지
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• 제33권3호
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• pp.365-374
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• 2020

Given a noncompact semisimple Lie group G and its maximal compact Lie subgroup K such that the right multiplication of each element in K gives an isometry on G, consider a principal bundle G → G/K, which is a Riemannian submersion. We study the infinitesimal holonomy isometries. Given a closed curve at eK in the base space G/K, consider the holonomy displacement of e by the horizontal lifting of the curve. We prove that the correspondence is continuous.

• 호남수학학술지
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• 제46권2호
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• pp.249-266
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• 2024

In this work, we study time-like and space-like surfaces invariant by a group of translation isometries of the half-space model ℋ³₁ of the anti-de Sitter space ℍ³₁ . We determine all such surfaces with constant mean curvature and constant Gaussian curvature. We also obtain umbilical surfaces of ℋ³₁.

• 전자공학회논문지CI
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• 제45권5호
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• pp.110-116
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• 2008

본 논문은 Isometric SOM(ISOSOM)신경망을 이용하여 지문의 영상의 세선화 과정에서 발생하는 거짓 특징점의 제거를 위한 새로운 후처리 방법과 영상압축에 관한 것이다. SOM은 간단한 구조와 빠른 실행 시간, 그리고 비교적 뛰어난 분류 성능 등의 장점을 가지므로, 영상압축, 패턴분류 등과 같이 많은 영상관련 분야에 적용되고 있으나, 단층의 구조를 가지고 있으므로 패턴의 분류에 한계성을 가지고 있다. 본 논문은 적은 벡터 코드북 개수로 SOM의 패턴분류 특성을 최대화시키기 위하여 fractal의 isometry를 적용한 Isometric SOM을 사용하였다. 제안된 Isometric SOM을 이용한 지문영상의 후처리 및 압축 알고리즘은 거짓 특징점의 추출에 좋은 성능을 보였으며 동시에 압축을 수행하는 우수한 성능을 확인할 수 있었다.

• 대한수학회지
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• 제52권4호
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• pp.869-889
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• 2015

Let ${\Gamma}^+$ be the positive cone in a totally ordered abelian group ${\Gamma}$, and ${\alpha}$ an action of ${\Gamma}^+$ by extendible endomorphisms of a $C^*$-algebra A. Suppose I is an extendible ${\alpha}$-invariant ideal of A. We prove that the partial-isometric crossed product $\mathcal{I}:=I{\times}^{piso}_{\alpha}{\Gamma}^+$ embeds naturally as an ideal of $A{\times}^{piso}_{\alpha}{\Gamma}^+$, such that the quotient is the partial-isometric crossed product of the quotient algebra. We claim that this ideal $\mathcal{I}$ together with the kernel of a natural homomorphism $\phi:A{\times}^{piso}_{\alpha}{\Gamma}^+{\rightarrow}A{\times}^{iso}_{\alpha}{\Gamma}^+$ gives a composition series of ideals of $A{\times}^{piso}_{\alpha}{\Gamma}^+$ studied by Lindiarni and Raeburn.

• 대한수학회지
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• 제55권5호
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• pp.1235-1255
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• 2018

We provide definitions for the helicoidal Killing field and the helicoid in arbitrary three-manifolds, and investigate helicoids and ruled minimal surfaces in homogeneous three-manifolds, mainly in $SL_2{\mathbb{R}}$ and Sol(3). In so doing we finish our classification of ruled minimal surfaces in homogeneous three-manifolds with the isometry group of dimension 4.

• 한국통신학회논문지
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• 제22권6호
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• pp.1279-1288
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• 1997

In this paper, we propose a fast fractal coding method based on LMSE analysis and subblock feature. In the proposed method, scaling paarameter is calculated and whether search for each domain block should be done or not is determined based on the LMSE analysis of fractal approximation, and isometry parameter is chosen based on subblock feature. To investigate the efficiency of the proposed method, we compared it with Jacquin's method on image quality and encoding time. Experimental results show the proposed method yields nearly the same performance as that of Jacquin method in PSNR, and its encoding time is reduced by about 1/7 times.

• 한국위성정보통신학회논문지
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• 제8권4호
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• pp.130-134
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• 2013

본 논문에서는 3D 방송의 기본적인 원리를 설명하고 3D 방송을 CS 기술을 적용하여 데이터 용량을 줄이는 방식을 제안한다. 샘플링 이론과 CS 기술의 차이점을 설명하고 개념과 동작원리를 설명한다. 최근 제안된 CS 센싱의 복원 알고리즘인 AMP(Approximate Message Passing)와 CoSaMP(Compressive Sampling Matched Pursuit)를 소개하고 이를 이용하여 이미지 데이터를 압축 복원하여 비교한다. 두 알고리즘의 계산시간을 비교하여 낮은 복잡도를 갖는 알고리즘을 판단한다.