• Journal of applied mathematics & informatics
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• 제27권3_4호
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• pp.749-755
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• 2009

In this paper, we investigate the invariant interval, periodic character, semicycle and global attractivity of all positive solutions of the equation $Y_{n+1}\;=\;\frac{p+qy_{n-k}}{1+y_n+ry_{n-k}}$, n = 0, 1, ..., where the parameters p, q, r and the initial conditions $y_{-k}$, ..., $y_{-1}$, $y_0$ are positive real numbers, k $\in$ {1, 2, 3, ...}. It is worth to mention that our results solve the open problem proposed by Kulenvic and Ladas in their monograph [Dynamics of Second Order Rational Difference Equations: with Open Problems and Conjectures, Chapman & Hall/CRC, Boca Raton, 2002]

• 한국경영과학회지
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• 제36권3호
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• pp.75-90
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• 2011

Suggesting that endorser fit in print advertising can be subdivided into observable endorser-product fit, unobservable endorser-product fit, and observable endorser-background fit, this study empirically investigates their effects on advertising effectiveness. Undergraduate students participated in the study and evaluated three real advertisements on the items of the fits, the advertising effectiveness, and so on. The advertisements were for a watch, perfume, and women's clothing. Results showed that each of fits had an positive effect on advertising attitude, brand attitude, and purchase intention respectively and the observable endorser-product fit had a more positive effect on such an effectiveness than the unobservable endorser-product fit and the observable endorser-background fit in the majority of cases. It was also found that each of the fits had a tendency to exert relatively greater effects on the advertising effectiveness, especially on the purchase intention, compared to the endorser preference.

• 한국군사과학기술학회지
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• 제3권2호
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• pp.61-70
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• 2000

An Adaptive Positive Position Feedback method is presented for controlling the roll of the supersonic smart projectile. The proposed strategy combines the attractive attributes of Positive Position Feedback(PPF) of Goh and Caughey, and Lyapunov stability theorem. The parameters of Adaptive-PFF controller are adjusted in an adaptive mauler in order to follow the performance of an optimal reference model. In this way, optimal damping and zero steady-state errors can be achieved even in the presence of uncertain or changing plant parameters. The performance obtained with the Adaptive-PPF algorithm is compared with conventional PPF control algorithm. The results obtained emphasize the potential of Adaptive-PPF algorithm as an efficient means for controlling plants such as supersonic flight systems with uncertainties in real time.

• 대한안전경영과학회지
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• 제19권1호
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• pp.145-156
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• 2017

This study was conducted to grasp problems of the present and investigate the real condition of organizations by making how an organizational ISO/TS 16949 quality management system has a positive effect on process improvement, perceived organizational support has a significant effect on the relationship between ISO/TS 16949 requirements and process improvement, process improvement has a positive effect on customer satisfaction and organizational performance research projects. For doing them, it tris to suggest an effective application plan of ISO/TS 16949 certification through improvements about corporate quality management systems of the automobile field by investigating and analyzing literature of the precedent studies and ISO/TS 16949 certification effects actually, conducting and analyzing an survey on effects on customer satisfaction and organizational performance, and drawing the problems.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제6권2호
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• pp.55-64
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• 2002

According to changing the society rapidly in the 21s1 century, the self-regulated learning ability is considered as an ability of which people should carry on their lives. The purpose of this study was to investigate prospective elementary school teachers in mathematics teaching method class in terms of the following areas: (1) the degree of their abilities shown the lower level factors of motivated strategies for learning such as self-efficacy, intrinsic value, anxiety, cognitive strategy use, and self-regulation (2) relations between factors of motivated strategies for loaming and performance of prospective elementary school teachers The results show that the prospective elementary school teachers showed above the mean value of the motivated strategies for learning and there are positive relations among lower level factors of motivated strategies fur learning except anxiety, positive relation between motivated strategies for learning and achievement. In order to help the prospective elementary school teacher to improve their motivated strategies fur learning in their elementary mathematics teaching method lecture, several methods such as mathematical connections to real world problem, history of mathematics and interview with mathematicians and application of feller's ARCS model to elementary mathematics education are suggested.

• Communications for Statistical Applications and Methods
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• 제23권6호
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• pp.575-585
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• 2016

Longitudinal studies repeatedly measure outcomes over time. Therefore, repeated measurements are serially correlated from same subject (within-subject variation) and there is also variation between subjects (between-subject variation). The serial correlation and the between-subject variation must be taken into account to make proper inference on covariate effects (Diggle et al., 2002). However, estimation of the covariance matrix is challenging because of many parameters and positive definiteness of the matrix. To overcome these limitations, we propose autoregressive moving average Cholesky decomposition (ARMACD) for the linear mixed models. The ARMACD allows a class of flexible, nonstationary, and heteroscedastic models that exploits the structure allowed by combining the AR and MA modeling of the random effects covariance matrix. We analyze a real dataset to illustrate our proposed methods.

• Communications for Statistical Applications and Methods
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• 제27권2호
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• pp.201-210
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• 2020

Baseline-category logit random effects models have been used to analyze longitudinal nominal data. The models account for subject-specific variations using random effects. However, the random effects covariance matrix in the models needs to explain subject-specific variations as well as serial correlations for nominal outcomes. In order to satisfy them, the covariance matrix must be heterogeneous and high-dimensional. However, it is difficult to estimate the random effects covariance matrix due to its high dimensionality and positive-definiteness. In this paper, we exploit the modified Cholesky decomposition to estimate the high-dimensional heterogeneous random effects covariance matrix. Bayesian methodology is proposed to estimate parameters of interest. The proposed methods are illustrated with real data from the McKinney Homeless Research Project.

• Kyungpook Mathematical Journal
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• 제61권3호
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• pp.631-644
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• 2021

In the present paper, we obtain gradient estimates for positive solutions to the following nonlinear parabolic equation under general geometric flow on complete noncompact manifolds $$\frac{{\partial}u}{{\partial}t}={\Delta}u+a(x,t)u^p+b(x,t)u^q$$ where, 0 < p, q < 1 are real constants and a(x, t) and b(x, t) are functions which are C² in the x-variable and C¹ in the t-variable. We shall get an interesting Harnack inequality as an application.

• 충청수학회지
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• 제35권4호
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• pp.315-327
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• 2022

In this paper, we investigate the transferred superstability for the p-radical sine functional equation $$f\(\sqrt[p]{\frac{x^p+y^p}{2}}\)^2-f\(\sqrt[p]{\frac{x^p-y^p}{2}}\)^2=f(x)f(y)$$ from the p-radical functional equations: $$f({\sqrt[p]{x^p+y^p}})+f({\sqrt[p]{x^p-y^p}})={\lambda}g(x)g(y),\;\\f({\sqrt[p]{x^p+y^p}})+f({\sqrt[p]{x^p-y^p}})={\lambda}g(x)h(y),$$ where p is an odd positive integer, λ is a positive real number, and f is a complex valued function. Furthermore, the results are extended to Banach algebras. Therefore, the obtained result will be forced to the pre-results(p=1) for this type's equations, and will serve as a sample to apply it to the extension of the other known equations.

• Journal of Dairy Science and Biotechnology
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• 제33권3호
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• pp.197-202
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• 2015

While various foodborne pathogenic bacteria can be detected more rapidly via polymerase chain reaction than via conventional plating methods, it is impossible to distinguish between viable and dead cells in DNA-based assays. Hence, propidium monoazide (PMA) treatment has been introduced to detect living cells. The purpose of this study is to evaluate the applicability of the PMA treatment and real-time qPCR method for the detection of Cronobacter sakazakii and to compare it to that of plate counting. Based on our positive results, we suggest the use of PMA treatment and real-time qPCR for the detection of viable Cronobacter sakazakii in various food sources and an update of the Korean Food Code.