• 호남수학학술지
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• 제22권1호
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• pp.47-52
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• 2000

We determine the Shilov and Choquet boundaries and the set of peak points of Lipschitz algebras $Lip(X,\;{\alpha})$ for $0<{\alpha}{\leq}1$, and $lip(X,\;{\alpha})$ for $0<{\alpha}<1$, on a compact metric space X. Then, when X is a compact subset of $\mathbb{C}^n$, we define some subalgebras of these Lipschitz algebras and characterize their Shilov and Choquet boundaries. Moreover, for compact plane sets X, we determine the Shilove boundary of them. We also determine the set of peak points of these subalgebras on certain compact subsets X of $\mathbb{C}^n$.

• 충청수학회지
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• 제32권4호
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• pp.393-400
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• 2019

Pajoohesh introduced the concept of k-metric spaces and Hiltzler and Seda defined the concept of metric-like spaces. Recently, Kopperman and Pajoohesh proved a fixed point theorem in complete k-metric spaces for a Lipschitz map with bound. In this paper, we prove a fixed point theorem in complete metric-like spaces for a Lipschitz map with bound.

• East Asian mathematical journal
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• 제29권1호
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• pp.91-99
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• 2013

In this paper, we prove that the BMO norm and the Garsia norm are equivalent on a bounded domain in $\mathbb{R}^N$. Also, we investigate the equivalent relation between the Lipschitz norm and the Garsia-type norm for harmonic functions.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제18권4호
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• pp.345-351
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• 2011

Taylor's formula is a powerful tool in analysis. In this study, we assume that an operator is m-times Fr$\acute{e}$chet-differentiable and satisfies a Lipschitz condition. We then obtain some Taylor formulas using only the Lipschitz constants. Applications are also provided.

• 대한수학회논문집
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• 제16권4호
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• pp.667-677
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• 2001

We consider a nonsmooth multiobjective opimization problem(PE) involving locally Lipschitz functions and define gen-eralized invexity for locally Lipschitz functions. Using Fritz John type optimality conditions, we establish Fritz John type sufficient optimality theorems for (PE) under generalized invexity.

• 충청수학회지
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• 제30권2호
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• pp.273-284
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• 2017

In this paper, we study that the solutions to perturbed differential system $$y^{\prime}=f(t,y)+{{\displaystyle\smashmargin{2}{\int\nolimits_{t_0}}^{t}}g(s,y(s),T_1y(s))ds+h(t,y(t),T_2y(t))$$ have uniformly Lipschitz stability by imposing conditions on the perturbed part ${\int_{t0}^{t}}g(s,y(s),T_1y(s))ds,h(t,y(t),T_2y(t))$, and on the fundamental matrix of the unperturbed system y' = f(t, y) using integral inequalities.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제23권1호
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• pp.1-12
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• 2016

This paper shows that the solutions to the perturbed differential system $y^{\prime}=f(t, y)+\int_{to}^{t}g(s,y(s),Ty(s))ds+h(t,y(t))$ have asymptotic property and uniform Lipschitz stability. To show these properties, we impose conditions on the perturbed part $\int_{to}^{t}g(s,y(s),Ty(s))ds+h(t,y(t))$, and on the fundamental matrix of the unperturbed system y' = f(t, y).

• 대한수학회지
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• 제49권6호
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• pp.1301-1321
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• 2012

In this paper we study the unique solvability of backward stochastic Volterra integral equations (BSVIEs in short), in terms of both the adapted M-solutions introduced in [19] and the adapted solutions via a new method. A general existence and uniqueness of adapted M-solutions is proved under non-Lipschitz conditions by virtue of a briefer argument than the ones in [13] and [19], which modifies and extends the results in [13] and [19] respectively. For the adapted solutions, the unique solvability of BSVIEs under more general stochastic non-Lipschitz conditions is shown, which improves and generalizes the results in [7], [14] and [15].

• 한국항공우주학회지
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• 제42권10호
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• pp.816-822
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• 2014

위성의 각속도를 추정하는 비선형 관측기의 설계방법을 제안한다. SDRE 기법을 이용하여 관측기를 설계하는데, 오차 수렴에 대한 충분조건을 제시하였다. 대수 Riccati 형태의 이 조건은, 비선형 항을 Lipschitz 형태로 변환하고 이에 대한 수렴 조건을 유도하여 구해진다. 이 조건으로부터 관측기의 게인을 구할 수 있으며, 시뮬레이션을 이용하여 제안한 방법을 검증하였다.

• 제어로봇시스템학회논문지
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• 제14권11호
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• pp.1089-1093
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• 2008

This paper presents a robust state observer design for a class of Lipschitz nonlinear systems with time delay and external disturbance. Sufficient conditions on the existence of the proposed observer are characterized by linear matrix inequalities. It is also shown that the proposed observer design can reduce the effect on the estimation error of external disturbance up to the prescribed level in spite of the existence of time delay. Finally, a numerical example is provided to verify the proposed design method.