• Communications of the Korean Mathematical Society
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• v.22 no.4
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• pp.609-621
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• 2007

Comparison of high Mach number jets using positive schemes and Weighted ENO methods is considered in this paper. The positive scheme introduced by [11, 14] and Weighted ENO [9, 10] have allowed us to simulate very high Mach numbers more than Mach 80. Simulations at high Mach numbers and with radiative cooling are essential for achieving detailed agreement with astrophysical images.

• Korean Journal of Mathematics
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• v.18 no.3
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• pp.299-309
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• 2010

In this paper, we study the first order nonlinear neutral difference equation: $${\Delta}(x(n)+px(n-{\tau}))+f(n,x(n-c),x(n-d))=r(n),\;n{\geq}n_0$$. Using the Banach fixed point theorem, we prove the existence of bounded positive solutions of the equation, suggest Mann iterative schemes of bounded positive solutions, and discuss the error estimates between bounded positive solutions and sequences generated by Mann iterative schemes.

• Bulletin of the Korean Mathematical Society
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• v.52 no.5
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• pp.1683-1709
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• 2015

Let (${\Omega}$, S) be an association scheme where ${\Omega}$ is a non-empty finite set and S is a partition of ${\Omega}{\times}{\Omega}$. For a positive integer k we say that (${\Omega}$, S) is k-equivalenced if each non-diagonal element of S has valency k. In this paper we focus on 4-equivalenced association schemes, and prove that they are transitive.

• Parasites, Hosts and Diseases
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• v.35 no.4
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• pp.265-270
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• 1997

To assess several chemotherapeutic schemes for control of enterobiasis, 738 children in five primary schools in Chunchon, Korea, were studied from May 1994 to June 1995. They were divided into 6 groups by the schemes: treatment of once or hice a year; treatment of positive cases or of whole class students; treatment with or without family members. The overall egg Positive rate before intervention was 17.5% out of 789 children. Treating all individuals in a class together with family members of positive cases brought better control efficacy than other schemes (P=0.000). However, when egg Positive rate is less than 30%, treating only egg Positive cases also can reduce egg Positive rate. The con- founding factors for the enterobiasis control in primary schoolchildren were new-comer to a class and familial infection.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.2
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• pp.199-205
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• 2004

Though Public Participation in the field of landscape architecture in China is still in an initial process, it has brought positive effects. The public exhibition of important landscape planning and design schemes is part of current public participation in China. The aim of it is to seek the opinion of the broad masses. Based upon particular situations in China, this paper analyzes two latest significant cases, public exhibitions of Landscape Design Schemes of Beijing Olympic Green & the Central Zone and Beijing South Axis Road Green Space Planning Schemes, pointing out that media introduction, voting, and feedback are three indispensable sections of Public Participation. The approaches by making full use of public exhibitions to create a partnership in public participation are also examined.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.9
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• pp.4788-4813
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• 2019

In this paper, we introduce concepts of optimal and near optimal secret data hiding schemes. We present a new digital image steganography approach based on the Galois field $GF(p^m)$ using graph and automata to design the data hiding scheme of the general form ($k,N,{\lfloor}{\log}_2p^{mn}{\rfloor}$) for binary, gray and palette images with the given assumptions, where k, m, n, N are positive integers and p is prime, show the sufficient conditions for the existence and prove the existence of some optimal and near optimal secret data hiding schemes. These results are derived from the concept of the maximal secret data ratio of embedded bits, the module approach and the fastest optimal parity assignment method proposed by Huy et al. in 2011 and 2013. An application of the schemes to the process of hiding a finite sequence of secret data in an image is also considered. Security analyses and experimental results confirm that our approach can create steganographic schemes which achieve high efficiency in embedding capacity, visual quality, speed as well as security, which are key properties of steganography.

• Journal of applied mathematics & informatics
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• v.40 no.3_4
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• pp.531-543
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• 2022

The article proposed a new type of data relationship: Positive Boolean dependencies by groups on block and slice in the database model of block form, where instead of considering value pairs, we consider a group of p values (p ≥ 2). From this new concept, the article stated and demonstrated the equivalence of the three types of deduction, namely: deduction by logic, deduction by block with groups, deduction by block has no more than p elements with groups. Operations on blocks or slices performed for index attributes on blocks, the properties related to this new concept as theorem the equivalen of the three types of deduction, closure of set positive Boolean dependencies by groups and representation and tight representation set of positive Boolean dependencies by groups when the block degenerated into relation are true in the relational database model and also stated and proven in this paper.

• Journal of the Korean Mathematical Society
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• v.32 no.4
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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 $0 < T < \infty$.

• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.417-426
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• 2011

This paper is concerned with the existence of monotone positive solutions for a class of nonlinear third-order three-point boundary value problem. By applying iterative techniques, we not only obtain the existence of monotone positive solutions, but also establish iterative schemes for approximating the solutions. An example is also included to illustrate the importance of the results obtained.

• Journal of applied mathematics & informatics
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• v.27 no.3_4
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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.