• Journal of the Korean Mathematical Society
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• 제59권5호
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• pp.911-926
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• 2022

Let u be a function on a locally finite graph G = (V, E) and Ω be a bounded subset of V. Let 𝜀 > 0, p > 2 and 0 ≤ λ < λ₁(Ω) be constants, where λ₁(Ω) is the first eigenvalue of the discrete Laplacian, and h : V → ℝ be a function satisfying h ≥ 0 and $h{\not\equiv}0$. We consider a perturbed Yamabe equation, say $$\{\begin{array}{lll}-{\Delta}u-{\lambda}u={\mid}u{\mid}^{p-2}u+{\varepsilon}h,&&\text{ in }{\Omega},\\u=0,&&\text{ on }{\partial}{\Omega},\end{array}$$ where Ω and ∂Ω denote the interior and the boundary of Ω, respectively. Using variational methods, we prove that there exists some positive constant 𝜀₀ > 0 such that for all 𝜀 ∈ (0, 𝜀₀), the above equation has two distinct solutions. Moreover, we consider a more general nonlinear equation $$\{\begin{array}{lll}-{\Delta}u=f(u)+{\varepsilon}h,&&\text{ in }{\Omega},\\u=0,&&\text{ on }{\partial}{\Omega},\end{array}$$ and prove similar result for certain nonlinear term f(u).

• Communications of the Korean Mathematical Society
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• 제38권3호
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• pp.741-754
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• 2023

In this paper, we study the existence and nonexistence of solutions for a class of Hamiltonian strongly degenerate elliptic system with subcritical growth $$\left{\array{-{\Delta}_{\lambda}u-{\mu}v={\mid}v{\mid}^{p-1}v&&\text{in }{\Omega},\\-{\Delta}_{\lambda}v-{\mu}u={\mid}u{\mid}^{q-1}u&&\text{in }{\Omega},\\u=v=0&&\text{ on }{\partial}{\Omega},}$$ where p, q > 1 and Ω is a smooth bounded domain in ℝ^N, N ≥ 3. Here Δ_λ is the strongly degenerate elliptic operator. The existence of at least a nontrivial solution is obtained by variational methods while the nonexistence of positive solutions are proven by a contradiction argument.

• Journal of the Korean Society of Clothing and Textiles
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• 제25권8호
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• pp.1444-1452
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• 2001

Textile materials are frequently in contact with surfactant solutions during their manufacturing or finishing processes as well as cleaning processes in use. Liquid wetting, wicking and absorbency of textile materials, and the liquid properties, surface characteristics and pore geometry of textile materials, and the liquie-solid interactions, In this paper, 10 different nonionic surfactants, including Span 20, Twen 20, 40, 60, 80, 21, 61, 81, 65, 85, were used. The surfactants were characterized by their hydrophile-lipophile-balance (HLB) values, structures, and surface tensions. The 0.1g/dL and 1.0g/dL surfactant solutions, which were both above critical micelle concentration (CMC), were used to see the concentration effects on the wetting and absorbency of cotton fabrics. The wetting behavior and liquid retention properties of hydrophobic cotton fabrics with different nonionic surfactant solutions are reported. The contact angles are greatly decreased and the water retention values are greatly increased by adding most of the surfactants studied into the system. The extents of this effects are influenced by the characteristics of surfactants and its solutions. Hydrophilic surfactants which have low number of carbon atoms or unsaturated hydrophobe structures are more effective in improving the wetting and absorbancy of hydrophobic cotton fabrics. The water retention of hydrophobic cotton fabrics has positive relations with $cos{\theta}$, adhesion tension and work of adhesion. The 1.0g/dL surfactant solutions show similar, but slightly improved wetting and absorbency characteristics of hydrophobic cotton fabrics compared to the 0.1g/dL surfactant solutions.

• Journal of the Korea Society of Computer and Information
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• 제21권5호
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• pp.99-109
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• 2016

Creative performance has been regarded as the key to the success of an organization in recent years, and is considered essential for the survival of an organization. Organizations must find and develop creative solutions to deal with a variety of business issues. How can organizations become more creative? To develop creativity, organizations must make it easier to connect the knowledge and perspectives of its various members, who may be scattered around the world, by developing a virtual team. Drawing from the transactive memory systems (TMS), which include expertise location, credibility, and coordination, this study investigates how the positive affect of team members influences the development of creative performance during virtual collaboration where face-to-face team activities are limited. The proposed structured model was empirically tested with cross-sectional data from 322 individuals. Results indicated that the positive affect of team members was found to moderate the relationship between TMS and creativity. Through this study, we expect to provide an understanding of the mechanisms involved in developing creativity among team members in a virtual work environment.

• Bulletin of the Korean Mathematical Society
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• 제51권3호
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• pp.739-763
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• 2014

In this paper, the nonlinear matrix equation $$X+\sum_{i=1}^{m}A_i^*X^{-q}A_i=Q(0<q{\leq}1)$$ is investigated. Some necessary conditions and sufficient conditions for the existence of positive definite solutions for the matrix equation are derived. Two iterative methods for the maximal positive definite solution are proposed. A perturbation estimate and an explicit expression for the condition number of the maximal positive definite solution are obtained. The theoretical results are illustrated by numerical examples.

• Journal of applied mathematics & informatics
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• 제27권3_4호
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• pp.639-651
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• 2009

In this paper, we study a discrete Leslie-Gower one-predator two-prey model. By using the method of coincidence degree and some techniques, we obtain the existence of at least one positive periodic solution of the system. By linalization of the model at positive periodic solution and construction of Lyapunov function, sufficient conditions are obtained to ensure the global stability of the positive periodic solution. Numerical simulations are carried out to explain the analytical findings.

• Journal of the Chungcheong Mathematical Society
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• 제31권4호
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• pp.487-509
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• 2018

The Truncated Moment Problem (TMP) entails finding a positive Borel measure to represent all moments in a finite sequence as an integral; once the sequence admits one or more such measures, it is known that at least one of the measures must be finitely atomic with positive densities (equivalently, a linear combination of Dirac point masses with positive coefficients). On the contrary, there are more general moment problems for which we aim to find a "signed" measure to represent a sequence; that is, the measure may have some negative densities. This type of problem is referred to as the General Truncated Moment Problem (GTMP). The Jordan Decomposition Theorem states that any (signed) measure can be written as a difference of two positive measures, and hence, in the view of this theorem, we are able to apply results for TMP to study GTMP. In this note we observe differences between TMP and GTMP; for example, we cannot have an analogous to the Flat Extension Theorem for GTMP. We then present concrete solutions to lower-degree problems.

• Reproductive and Developmental Biology
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• 제30권1호
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• pp.71-74
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• 2006

Hypoosmotic swelling test (HOST) is used for evaluating the plasma membrane function and fertilizing ability in mammal spermatozoa. However, HOS solutions and experimental conditions have not been determined clearly for assessing canine spermatozoa. This study was conducted to examine the HOS solutions and assay conditions, including incubation time (30 to 120 min), storage temperature (4, 17 and $20^{\circ}C$), semen status (fresh and frozen). Maximum spermatozoal plasma membrane swelling was obtained in an 150 mOsm Na-citrate/Fructose solutions with an incubation time for 45 min. The storage temperature and semen status affected the percentage of HOS positive spermatozoa. The HOS test adapted to canine spermatozoa in this study was simple and highly consistent assay with good repeatability. The optimal condition of HOST in canine spermatozoa is an 150 mOsm Na-citrate/Fructose solutions with an incubation time for 45 min regardless of semen storage temperature and semen status.

• Journal of Sensor Science and Technology
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• 제30권5호
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• pp.326-330
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• 2021

Reactions between gold (Au) surface plasmon resonance (SPR) chips and bovine serum albumin (BSA) dissolved in solutions of different pH were investigated. The charge on the BSA depends on the pH of the solution in which it is dissolved. Thus, dissolving BSA in different pH solutions resulted in different charges of BSA. Among the BSA dissolved in solutions with pH 4.01, 7.4, and 10.01, the SPR response was the highest for BSA dissolved in the solution of pH 4.01. To eliminate the response variation owing to the difference in the refractive indices of the solutions, phosphate buffered saline (PBS) was injected into the system after the reaction of BSA with the Au SPR chip had happened. In this case too, the BSA dissolved in the solution with pH 4.01 exhibited the highest response. This may be attributed to the non-uniform distribution of ionic patches on the BSA, which can induce electrostatic attraction to the surface even though BSA has a positive charge at pH 4.01, and the absolute values of the net charge of BSA at pH 4.01 and 7.4 were very close.

• Journal of the Korean Mathematical Society
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• 제32권4호
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• pp.815-834
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• 1995

Let $\Omega$ be a rectangular domain in $R^2$ with boundary $\partial\Omega$, and T be a positive real number such that $0 < T < \infty$.