• Journal of Mechanical Science and Technology
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• v.15 no.11
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• pp.1499-1506
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• 2001

Various transition elements are used in general for the effective finite element analysis of complicated mechanical structures. In this paper, a solid-to-beam transition finite element, which can b e used for connecting a C1-continuity beam element to a continuum solid element, is proposed. The shape functions of the transition finite element are derived to meet the compatibility condition, and a transition element equation is formulated by the conventional finite element procedure. In order to show the effectiveness and convergence characteristics of the proposed transition element, numerical tests are performed for various examples. As a result of this study, following conclusions are obtained. (1) The proposed transition element, which meets the compatibility of the primary variables, exhibits excellent accuracy. (2) In case of using the proposed transition element, the number of nodes in the finite element model may be considerably reduced and the model construction becomes more convenient. (3) This formulation method can be applied to the usage of higher order elements.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.18 no.4
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• pp.337-350
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• 2014

In this paper, we consider discontinuous Galerkin finite element methods with interior penalty term to approximate the solution of nonlinear parabolic problems with mixed boundary conditions. We construct the finite element spaces of the piecewise polynomials on which we define fully discrete discontinuous Galerkin approximations using the Crank-Nicolson method. To analyze the error estimates, we construct an appropriate projection which allows us to obtain the optimal order of a priori ${\ell}^{\infty}(L^2)$ error estimates of discontinuous Galerkin approximations in both spatial and temporal directions.

• Kyungpook Mathematical Journal
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• v.61 no.3
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• pp.591-612
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• 2021

In this paper, a uniformly convergent numerical scheme is designed for solving singularly perturbed reaction-diffusion problems. The problem is converted to an equivalent weak form and then a Galerkin finite element method is used on a piecewise uniform Shishkin mesh with linear basis functions. The convergence of the developed scheme is proved and it is shown to be almost fourth order uniformly convergent in the maximum norm. To exhibit the applicability of the scheme, model examples are considered and solved for different values of a singular perturbation parameter ε and mesh elements. The proposed scheme approximates the exact solution very well.

• The Korean Journal of Food And Nutrition
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• v.35 no.2
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• pp.127-136
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• 2022

Comparing the quality characteristics of kimchi were measured and anticancer effects using AGS human gastric cancer cells were observed. Five kinds of kimchi samples were made of Kanghwa Baek kimchi (KB), Kangwha Turnip kimchi (KT), Turnip: Chinese cabbage = 1:1 Baek kimchi (T1B1), Turnip:Chinese cabbage = 4:1 Baek kimchi (T4B1), Turnip mul kimchi (T). As a result T kimchi showed the best fermentation characteristics among the five samples. T kimchi had a lower percentage of the total number of aerobic bacteria, while the number of lactobacillus was higher than that of other samples. The mRNA and protein expression levels of apoptosis-related factors found that T kimchi significantly increases the mRNA expression levels of caspases-3 and caspases-9 in AGS human gastric cancer cells as compared to the other kimchi samples. It showed high anticancer effects in the order of T, T1B1, and KB kimchi. As the anticancer effect of Turnip mul kimchi made only of turnip was higher, the higher the turnip content, the higher the anticancer effect. These results show that there were changes in fermentation characteristics such as pH, acidity, number of lactic acid bacteria, and anticancer effects according to the ratio of turnip and cabbage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1231-1243
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• 1997

Digital satellite communication channels have nonlinearities with memory due to saturation characteristics of traveling wave tube amplifier in the satellite and transmitter/receiver linear filters. In this paper, we propose a network structure and a learning algorithm for complex pi-sigma network (CPSK) and exploit CPSN in the problem of equalization of nonlinear satellite channels. The proposed CPSN is a complex-valued extension of real-valued pi-sigma network that is a higher-order feedforward network with fast learning while greatly reducing network complexity by utilizing efficient form of polynomials for many input variables. The performance of the proposed CPSN is demonstrated by computer simulations on the equalization of complex-valued QPSK input symbols distorted by a nonlinear channel modeled as a Volterra series and additive noise. The results indicate that the CPSN shows good equalization performance, fast convergence, and less computations as compared to conventional higher-order models such as Volterra filters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.10
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• pp.1831-1836
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• 2016

Phase noise spectrum distributions of signal generators for next-generation VSAT satellite system based on DVB-RCS2 were analyzed in this paper. The forward link of VSAT system utilizes the APSK higher-order modulation methods based on the DVB-S2 ACM, the modulation methods of the return link utilizes the higher-order PSK and QAM based on the DVB-RCS2. In digital satellite system using the higher-order modulation techniques, the phase noise have an effect on transmission performance, the transmission performance is dominantly degraded by the phase noise of signal generators in the transmission system. The phase noise spectrum distribution of signal generators are analyzed by considering the ACM conditions that adopts the modulation techniques and data rates due to satellite transmission environment. The proper phase noise spectrum distribution for next-generation VSAT system based on DVB-RCS2 are proposed from the analyzed phase noise spectrum characteristics.

• Journal of Environmental Science International
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• v.28 no.11
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• pp.907-915
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• 2019

This study aims to identify the most tolerant species under salinity stress from amongst Asteraceae and Poaceae. The seeds of six species were exposed to different concentrations of $CaCl_2$ (0, 9, 18, 45, 90 mM) and NaCl (0, 17, 34, 85, 170 mM), and germination was measured once every two days. The results indicated that percent germination of the six species of Asteraceae and Poaceae seeds were affected differently by changes in salinity concentration. Seed germination was reduced as salinity levels increase, and longer mean germination times correlated to lower percent germination and earlier germination cessation. Both Asteraceae and Poaceae seeds had the highest germination rates at 18 mM $CaCl_2$ and 34 mM NaCl, and seed germination and growth were severely reduced at salinities greater than 90 mM $CaCl_2$ and 170 mM NaCl. In the seeds of Poaceae, salt resistance was strong in the order of Miscanthus sinensis Andersson, Pennisetum alopecuroides (L.) Spreng., and Phragmites communis Trin. In the seeds of Asteraceae, salt resistance was strong in the order of Dendranthema zawadskii var. latilobum (Maxim.) Kitam, Aster yomena (Kitam.) Honda, and Dendranthema boreale (Makino) Ling ex Kitam.. Overall, the germination rate was higher in Asteraceae than in Poaceae. This study demonstrated that Dendranthema zawadskii var. latilobum (Maxim.) Kitam. is the most tolerant species and that a relationship exists between the salt tolerance of percent germination and the mean germination time in the leaves.

• Journal of Digital Convergence
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• v.19 no.7
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• pp.11-19
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• 2021

The purpose of the study is to explore a plan for effective education using virtual reality in English education. In order to achieve the purpose of the study, the perception of English education using virtual reality was comprehensively investigated and analyzed for teachers(n=20) in the field of English education. The results of the study reveal the followings: 1) Teachers are positively aware of the necessity of English education using virtual reality, but most teachers complained of a psychological burden on education using virtual reality; 2) negative responses were somewhat higher than positive responses to the expectation that virtual reality-based English content would be practical in the educational field; 3) In order to increase the effectiveness of English education using virtual reality, it is necessary to share experiences for educational experience of virtual reality and need to provide various virtual reality contents; and 4) For virtual reality educational application, there is a high demand for teaching and learning method education and training using virtual reality and provision of guidelines for education using virtual reality.

• Structural Engineering and Mechanics
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• v.54 no.3
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• pp.393-417
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• 2015

In this paper an 8-node quadrilateral assumed stress hybrid Mindlin plate element with $39{\beta}$ is presented. The formulation is based on complementary energy principle. The proposed element is free of shear locking and is capable of passing all the patch tests, especially the non-zero constant shear enhanced patch test. To accomplish this purpose, special attention is devoted to selecting boundary displacement interpolation and stress approximation in domain. The arbitrary order Timoshenko beam function is successfully used to derive the boundary displacement interpolation. According to the equilibrium equations, an appropriate stress approximation is rationally derived. Particularly, in order to improve element's accuracy, the assumed stress field is derived by employing $39{\beta}$ rather than conventional $21{\beta}$. The resulting element can be adopted to analyze both moderately thick and thin plates, and the convergence for the very thin case can be ensured theoretically. Excellent element performance is demonstrated by a wide of experimental evaluations.

• Journal of Convergence for Information Technology
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• v.11 no.3
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• pp.34-45
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• 2021

The purpose of this study was to investigate the major selection motivation, academic stress, self-efficacy and college life adjustment and identify influencing factors of college life adjustment in the crisis situation of COVID-19. 243 nursing students were selected from 2 regions through convenience sampling. Data were analyzed through descriptive statistics, t-test, ANOVA, Scheffé test, Pearson's correlation coefficients and multiple linear regression analysis using SPSS for Windows Ver. 22.0. The higher the major selection motivation and self-efficacy, the higher the college life adjustment. The lower the academic stress, the higher the college life adjustment. The factors influencing college life adjustment were self-efficacy, major selection motivation, monthly allowance, and the explanatory power of these variables for college life adjustment was 65.6%. Therefore, in order to improve the nursing students' college life adjustment, it is necessary to develop and apply college life adjustment program to increase self-efficacy.