• 한국수학교육학회지시리즈B:순수및응용수학
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• 제22권3호
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• pp.263-273
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• 2015

In this paper, a boundary version of Schwarz lemma is investigated. For the function holomorphic f(z) = a + c_pz^p + c_p+₁z^p+1 + ... defined in the unit disc satisfying |f(z) − 1| < 1, where 0 < a < 2, we estimate a module of angular derivative at the boundary point b, f(b) = 2, by taking into account their first nonzero two Maclaurin coefficients. The sharpness of these estimates is also proved.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제11권2호
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• pp.67-77
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• 2007

This paper is concerned with the proof of so-called Bramble-Hilbert Lemma. We present that $Poincar{\acute{e}}'s$ inequality in [3] implies one of results of Morrey which is crucial in the proof. In this point of view, we recognize that removing the average term in $Poincar{\acute{e}}'s$ inequality fulfills a crucial role in the proof of Bramble-Hilbert Lemma. It is accomplished by adding some polynomial of degree one less than the degree of the Sobolev space in the outset. So, the condition annihilating the set of polynomials $P_{k-1}$ of degree k - 1 is required necessarily in Bramble-Hilbert Lemma.

• 대한수학회논문집
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• 제34권2호
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• pp.543-555
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• 2019

In this paper, we give some results on ${\frac{zf^{\prime}(z)}{f(z)}}$ for the certain classes of holomorphic functions in the unit disc $E=\{z:{\mid}z{\mid}<1\}$ and on ${\partial}E=\{z:{\mid}z{\mid}=1\}$. For the function $f(z)=z^2+c_3z^3+c_4z^4+{\cdots}$ defined in the unit disc E such that $f(z){\in}{\mathcal{A}}_{\alpha}$, we estimate a modulus of the angular derivative of ${\frac{zf^{\prime}(z)}{f(z)}}$ function at the boundary point b with ${\frac{bf^{\prime}(b)}{f(b)}}=1+{\alpha}$. Moreover, Schwarz lemma for class ${\mathcal{A}}_{\alpha}$ is given. The sharpness of these inequalities is also proved.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제30권3호
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• pp.337-345
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• 2023

Different versions of the boundary Schwarz lemma for the 𝒩 (𝜌) class are discussed in this study. Also, for the function g(z) = z+b₂z²+b₃z³+... defined in the unit disc D such that g ∈ 𝒩 (𝜌), we estimate a modulus of the angular derivative of g(z) function at the boundary point 1 ∈ 𝜕D with g'(1) = 1 + 𝜎 (1 - 𝜌), where ${\rho}={\frac{1}{n}}{\sum\limits_{i=1}^{n}}g(c_i)={\frac{g^{\prime}(c_1)+g^{\prime}(c_2)+{\ldots}+g^{\prime}(c_n)}{n}}{\in}g^{\prime}(D)$ and 𝜌≠1, 𝜎 > 1 and c₁, c₂, ..., c_n ∈ 𝜕D. That is, we shall give an estimate below |g"(1)| according to the first nonzero Taylor coefficient of about two zeros, namely z = 0 and z ≠ 0. Estimating is made by using the arithmetic average of n different derivatives g'(c₁), g'(c₂), ..., g'(c_n).

• 대한수학회지
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• 제32권1호
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• pp.109-114
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• 1995

Before state precisely our main theorem, we want to make some brief historical comment.

• East Asian mathematical journal
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• 제14권1호
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• pp.99-106
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• 1998

We establish a version of Fernique lemma for Gaussian processes which plays an important role in studying their moduli of continuity properties and related limit theorems.

• 컴퓨터교육학회논문지
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• 제12권5호
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• pp.87-94
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• 2009

본 논문은 정규 언어에 대한 펌핑 정리를 학습하는 학생들을 돕기 위한 웹 기반 상호작용적 적응형 학습 시스템을 제안하고 있다. 본 시스템은 웹 기반 교육을 통해서 학습자들이 개인차에 따라 학습을 진행할 수 있도록 하고, 학습과 관련된 예제들을 연습하고 그에 대한 피드백을 즉시 제공받을 수 있는 상호작용의 기회를 제공한다. 특히, 본 시스템은 펌핑 정리의 각 증명 단계를 이해할 수 있는 적응적 비계를 제공한다. 펌핑 정리를 학습할 수 있는 기존의 시스템들과 달리 본 논문에서 제안하는 시스템은 가능한 오류들을 미리 정하여 각 오류에 대한 메시지들을 적응적으로 제공한다. 또한 학습자들이 직접 문자열을 셋으로 나누도록 함으로써 펌핑 정리를 정확히 이해하도록 도움을 준다.

• 대한수학회보
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• 제30권2호
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• pp.167-170
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• 1993

In this paper, X, X$_{1}$, X$_{2}$, .. will denote any sequence of pairwise independent random variables with common distribution, and b$_{1}$, b$_{2}$.. will denote any sequence of constants. Using Chung [2, Theorem 4.2.5] and the same idea as in Chow and Robbins [1, Lemma 1 and 2] we have the following lemma.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제22권2호
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• pp.169-178
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• 2015

In this paper, a boundary version of Carathéodory’s inequality is investigated. Also, new inequalities of the Carathéodory’s inequality at boundary are obtained and the sharpness of these inequalities is proved.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제10권4호
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• pp.225-232
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• 2003

In this paper, we consider the existence of the solutions to the generalized vector variational-type inequalities for set-valued mappings on Hausdorff topological vector spaces using Fan's geometrical lemma.