• 호남수학학술지
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• 제39권3호
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• pp.331-347
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• 2017

The aim of the present paper is to introduce a new subclass of meromorphic functions with positive coefficients defined by a certain integral operator and a necessary and sufficient condition for a function f to be in this class. We obtain coefficient inequality, meromorphically radii of close-to-convexity, starlikeness and convexity, convex linear combinations, Hadamard product and integral transformation for the functions f in this class.

• Journal of applied mathematics & informatics
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• 제9권2호
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• pp.531-542
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• 2002

In this paper we deal with a sequence of positive linear operators ${{R_n}}^{[$\beta$]}$ approximating functions on the unbounded interval [0, $\infty$] which were firstly used by K. balazs and J. Szabados. We give pointwise estimates in the framework of polynomial weighted function spaces. Also we establish a Voronovskaja type theorem in the same weighted spaces for ${{K_n}}^{[$\beta$]}$ operators, representing the integral generalization in Kantorovich sense of the ${{R_n}}^{[$\beta$]}$.

• 대한수학회보
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• 제50권6호
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• pp.1847-1854
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• 2013

The main concern of this paper is to study the dynamics of an n-dimensional ratio-dependent predator-prey system with diffusion. We study the dissipativeness, persistence of the system and it is shown that the unique positive constant steady state is globally asymptotically stable under some assumptions.

• 대한수학회보
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• 제50권5호
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• pp.1587-1598
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• 2013

In this paper, we obtain some gradient estimates for positive solutions to the following nonlinear parabolic equation $$\frac{{\partial}u}{{\partial}t}={\triangle}u-b(x,t)u^{\sigma}$$ under general geometric flow on complete noncompact manifolds, where 0 < ${\sigma}$ < 1 is a real constant and $b(x,t)$ is a function which is $C^2$ in the $x$-variable and $C^1$ in the$t$-variable. As an application, we get an interesting Harnack inequality.

• 미생물과산업
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• 제17권1호
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• pp.10-18
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• 1991

A phylogenetic comparison of homologous protein can often supplement genetic and biochemical analysis by revealing conserved structures that are critical for function(Waugh et al., 1989). I therefore isolated a secY homologue from B. subtilis, a gram positive bacterium evolutionary distant from E. coli. The comparison and interplay between these two bacterial systems should contribute greatly to our understanding of the functions and interactions within systems evolved for protein translocation in both prokaryotic and eukaryotic organisms.

• Journal of the Korean Statistical Society
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• 제31권3호
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• pp.343-357
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• 2002

This paper proposes a method for producing smooth and positive estimates of the intensity function of an inhomogeneous Poisson process based on the shrinkage of wavelet coefficients of the observed counts. The information projection is used in conjunction with the level-dependent thresholds to yield smooth and positive estimates. This work is motivated by and demonstrated within the context of a problem involving gamma-ray burst data in astronomy. Simulation results are also presented in order to show the performance of the information projection estimators.

• 대한수학회지
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• 제58권3호
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• pp.633-642
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• 2021

In this paper we consider the following strongly damped wave equation with variable-exponent nonlinearity u_tt(x, t) - ∆u(x, t) - ∆u_t(x, t) = |u(x, t)|^p(x)-2u(x, t), where the exponent p(·) of nonlinearity is a given measurable function. We establish finite time blow-up results for the solutions with non-positive initial energy and for certain solutions with positive initial energy. We extend the previous results for strongly damped wave equations with constant exponent nonlinearity to the equations with variable-exponent nonlinearity.

• 충청수학회지
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• 제33권4호
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• pp.445-468
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• 2020

A long-time behavior of global solutions for a dispersive-dissipative equation with time-dependent damping terms is investigated under null Dirichlet boundary condition. By virtue of an appropriate new Lyapunov function and the Lojasiewicz-Simon inequality, we show that any global bounded solution converges to a steady state and get the rate of convergence as well, when damping coefficients are integrally positive and positive-negative, respectively. Moreover, under the assumptions on on-off or sign-changing damping, we derive an asymptotic stability of solutions.

• Child Health Nursing Research
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• 제14권1호
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• pp.61-70
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• 2008

Purpose: The purpose of this study was to investigate the relationship between high school students' self-differentiation, family function and their level of stress. Method: A questionnaire which consisted of questions on general characteristics of the high school students, and 36 questions on self-differentiation, 17 questions on family function, and 37 questions on level of stress was used to collect the data. Participants were 201 second grade high school students from Bucheon City. Descriptive statistics, T-test, ANOVA, correlation and multiple regression were used with SPSS 10.0 to analyze the data. Results: The mean scores for self-differentiation, family function, and levels of stress were 3.27, 3.39, and 2.61 respectively. The relationship between self-differentiation and level of stress revealed a significant negative correlation. The relationship between self-differentiation and family function showed a significant positive correlation. The relationship between family function and stress level showed a significant negative correlation. Conclusion: The results of the study show that variation in level of stress was related to family regression, recognition/emotional function, family projection, role recognition and emotional support and emotional cutoff which together explained 40.9% of the variance in level of stress.

• 아동학회지
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• 제37권6호
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• pp.19-33
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• 2016

Objective: This study aimed to examine the prospective links among perspective taking, attachment security, and executive function and the mediating role of executive function on the relationship between attachment security and perspective taking. Methods: The participants included 147 preschoolers living in Gyeonggi. The data-analysis methods included descriptive statistics, independent t-tests, one-way ANOVAs, Pearson's correlation analysis, hierarchical multiple regression analysis, and the Sobel test. Results: First, preschoolers' perspective taking was significantly related to attachment security, and executive function. Furthermore, there was a significant association between attachment security and executive function. As expected, the correlations were positive in all cases. Second, the effects of attachment security on intention and emotion perspective takings were fully mediated by executive function when holding children's age and vocabulary constant. However, executive function did not predict thought perspective taking, whereas attachment security did. Conclusion: Given that parent-child attachment security might play an important role in child cognitive and socio-cognitive development, parents' endeavors to enhance the quality of the attachment relationship could be a fruitful path for preschoolers' developing executive capacities and perspective taking.