• Journal of the Chungcheong Mathematical Society
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• v.24 no.4
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• pp.639-663
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• 2011

Motivated by Agarwal and O'Regan ( Boundary value problems for general discrete systems on infinite intervals, Comput. Math. Appl. 33(1997)85-99), this article deals with the discrete type BVP of the infinite difference equations. The sufficient conditions to guarantee the existence of at least three positive solutions are established. An example is presented to illustrate the main results. It is the purpose of this paper to show that the approach to get positive solutions of BVPs by using multi-fixed-point theorems can be extended to treat BVPs for infinite difference equations. The strong Caratheodory (S-Caratheodory) function is defined in this paper.

• Journal for History of Mathematics
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• v.14 no.2
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• pp.149-154
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• 2001

In this paper we represent the Ahlfors function on the multiply connected planar domain, especially on an annulus and apply it to the Caratheodory metric.

• Bulletin of the Korean Mathematical Society
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• v.34 no.1
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• pp.29-34
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• 1997

Let $U = {z \in C : $\mid$z$\mid$ < 1}$ be the open unit disc in the complex plane and let N be the class of all analytic functions p in U with p(0) = 1.

• Journal of the Korean Mathematical Society
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• v.32 no.4
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• pp.661-678
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• 1995

In this paper we will estimate from above and below the values of the Bergman, Caratheodory and Kobayashi metrics for a vector X at z, where z is any point near a given point $z_0$ in the boundary of pseudoconvex domains in $C^n$.

• Bulletin of the Korean Mathematical Society
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• v.48 no.6
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• pp.1119-1124
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• 2011

In the present paper, we study the chaotic property of weighted composition operators acting on the holomorphic function space $H(\mathbb{U})$.

• Nonlinear Functional Analysis and Applications
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• v.27 no.4
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• pp.773-784
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• 2022

The purpose of the present paper is to estimate some real parts for certain analytic functions with some applications in connection with certain integral operators and geometric properties. Also we extend some known results as special cases of main results presented here.

• Bulletin of the Korean Mathematical Society
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• v.32 no.2
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• pp.201-204
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• 1995

Let N be the class of functions of the form $$ (1.1) p(z) = 1 + p_1 z + p_2 z^2 + \cdots $$ which are analytic in the open unit disk $U = {z : $\mid$z$\mid$ < 1}$. If $p(z) \in N$ satisfies $Rep(z) > 0 (z \in U)$, then p(z) is called a Caratheodory function (cf. Goodman [2]).

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.458-463
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• 1997

In this paper, we propose a variable structure control approach for the system with matched and unmatched uncertainty. By using time-varying sliding mode, the reaching mode is removed, and the design methodology represents a realistic design approach with quadratic criterion for systems incorporating both matched and unmatched uncertainties. The criterion contains states and linear part of input for all time. The practical application of the control strategy is presented in the design of a stability augmentation system for an aircraft is presented.

• Journal of the Korean Mathematical Society
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• v.37 no.5
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• pp.665-685
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• 2000

The aim of this paper is to obtain nonlinear operators in suitable spaces whise fixed point coincide with the solutions of the nonlinear boundary value problems ($\Phi$($\upsilon$'))'=f(t, u, u'), l(u, u') = 0, where l(u, u')=0 denotes the Dirichlet, Neumann or periodic boundary conditions on [0, T], $\Phi$: N N is a suitable monotone monotone homemorphism and f:[0, T] N N is a Caratheodory function. The special case where $\Phi$(u) is the vector p-Laplacian $\mid$u$\mid$p-2u with p>1, is considered, and the applications deal with asymptotically positive homeogeneous nonlinearities and the Dirichlet problem for generalized Lienard systems.

• Korean Journal of Mathematics
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• v.16 no.1
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• pp.91-101
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• 2008

Let H be a Hilbert space. Assume that $0{\leq}{\alpha}$, ${\beta}{\leq}1$ and r(t) > 0 in I = [0, T]. By means of the fixed point theorem of Leray-Schauder type the existence principles of solutions for two point boundary value problems of the form $\array{(r(t)x^{\prime}(t))^{\prime}+f(t,x(t),r(t)x^{\prime}(t))=0,\;t{\in}I\\x(0)=x(T)=0}$ are established where f satisfies for positive constants a, b and c ${\mid}{f(t,x,y){\mid}{\leq}a{\mid}x{\mid}^{\alpha}+b{\mid}y{\mid}^{\beta}+c\;\;for\;all(t,x,y){\in}I{\times}H{\times}H$.