• Journal of applied mathematics & informatics
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• v.28 no.5_6
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• pp.1445-1460
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• 2010

In this paper, a second-order system of multi-point boundary value problems in Banach spaces is investigated. Based on a specially constructed cone and the fixed point theorem of strict-set-contraction operators, the criterion of the existence and multiplicity of positive solutions are established. And two examples demonstrating the theoretic results are given.

• Journal of the Chungcheong Mathematical Society
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• v.3 no.1
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• pp.41-48
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• 1990

Let D' : $C^n$[0, 1] ${\rightarrow}$ M be a second order derivation from the Banach algebra of n times continuously differentiable functions on [0, 1] into a Banach $C^n$[0, 1]-module M and let D be the primitive of D'. If D' is continuous and D'(z) lies in the 1-differential subspace, then it is completely determined by D(z) and D'(z) where z(t)=t, $0{\leq}t{\leq}1$.

• Korean Journal of Mathematics
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• v.26 no.4
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• pp.747-756
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• 2018

We study a maximum principle for a uniformly elliptic second order differential operator in nondivergence form. We allow a bounded positive zeroth order coefficient in a certain type of unbounded domains. The results extend a result by J. Busca in a sense of domains, and we present a simple proof based on local maximum principle by Gilbarg and Trudinger with iterations.

• Honam Mathematical Journal
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• v.45 no.2
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• pp.359-379
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• 2023

In the present paper, we study translation hypersurfaces in E⁴. In this context, firstly we obtain first, second and third Laplace-Beltrami (LB^I, LB^II and LB^III) operators of the translation hypersurfaces in E⁴. By solving second and third order nonlinear ordinary differential equations, we prove theorems that contain LB^I-minimal, LB^II-minimal and LB^III-minimal translation hypersurfaces in E⁴.

• Journal of applied mathematics & informatics
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• v.42 no.2
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• pp.417-432
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• 2024

In this research article, we study a class of semirings with involution. Differential identities involving two or three derivations of a semiring with second kind involution are investigated. It is analyzed that how these identities, with a special role for second kind involution, bring commutativity to semirings.

• Journal of Preventive Medicine and Public Health
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• v.42 no.3
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• pp.199-207
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• 2009

Objectives : Research on the gender differences of health among older Korean people has been limited compared with the research for other stages of life. This study first examined the patterns and magnitude of the gender differences of health in later life. Second, we examined the gender differences in the health of older men and women that were attributable to differing socioeconomic conditions. Methods : Using the nationally representative 2005 Korean National Health and Nutrition Examination Survey, the gender differences in disability and subjective poor health were assessed by calculating the age adjusted and gender-specific prevalence. Logistic regression analyses were used to assess if the differences between the men and women for health could be explained by differential exposure to socioeconomic factors and/or the differential vulnerability of men and women to these socioeconomic factors. Results : Our results indicated that older women were more likely than the men to report disability and poor subjective health. The health disadvantage of older women was diminished by differential experiences with socioeconomic factors, and especially education. The differences shrink as much as 43.7% in the case of disability and 35.4% in the case of poor subjective health by the differential exposure to educational attainment. Any differential vulnerability to socioeconomic factors was not found between the men and women, which means that socioeconomic factors may have similar effect on health in both genders. Conclusions : Differential socioeconomic experience and exposure between the men and women might cause gender difference in health in old age Koreans.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1243-1252
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• 2000

The differential enhanced degradation of cis- and trans-1,3-D was observed in the previous two studies performed by several researchers. This study was initiated to investigate the involvement of microorganisms in the differential enhanced degradation of the chemicals. As expected, microorganisms were responsible for the enhanced degradation. A mixed bacterial culture capable of degrading 1,3-D was isolated from an enhanced soil sample collected from a site treated with 1,3-D. Similar to the enhanced soil, the mixed culture degraded trans-1,3-D faster than cis-1,3-D. This mixed culture could not utilize cis- and trans-1,3-D as a sole source of carbon for growth. Rather, a variety of second substrates were evaluated to stimulate the differential enhanced degradation of the two isomers. As a result, the mixed culture degraded cis- and trans-1,3-D only in the presence of a suitable second substrate. Therefore, it appeared that the degradation of cis- and trans-1,3-D was a cometabolic process. Second substrates that had the capacity to stimulate the degradation included soil leachate, tryptone, tryptophan, and alanine. Other substrates tested. including soil extract. glucose, yeast extract and indole, failed to stimulate the degradation of the two isomers. The mixed culture was composed of four morphologically distinctive colonies on L-agar plates.

• Journal of applied mathematics & informatics
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• v.17 no.1_2_3
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• pp.787-796
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• 2005

We generalize a characterization of classical orthogonal polynomials and obtain a two-variable analogue. Also an example is given arising from a second order partial differential equation.

• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.39-48
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• 2011

Some existence theorems are obtained for periodic solutions of nonautonomous second-order differential systems with (q, p)-Laplacian by the minimax methods in critical point theory.

• Kyungpook Mathematical Journal
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• v.27 no.1
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• pp.7-13
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• 1987

This paper is a study of the oscillatory and asymptotic behaviour of solutions of the second order nonhomogeneous linear differential equation y"+P(x)y=f(x), and the associated homogeneous equation. Conditions are determined, under which the nonhomogeneous equation is oscillatory if and only if the homogeneous equation is oscillatory.