• Journal of Korean Home Economics Education Association
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• v.25 no.1
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• pp.55-66
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• 2013

The purposes of this study were to examine major satisfaction and career decision level of Home Economics Education major college students, to investigate factors influencing on major satisfaction and career decision level, and to provide basic informations for career counseling. A survey was conducted to students majoring Home Economics Education at four universities, and students majoring Korean Language Education and Mathematics Education at one same university in Seoul from October to November, 2011. General satisfaction in major of Home Economics Edu. students was above average, but social perception satisfaction was low. The social perception satisfaction was lower for Home Economics edu. students than Korean Language edu. and Mathematics edu. students. There were significant differences in major satisfaction by university and class standing, but no significant difference by gender. Students showed the lowest value in Home Economics teacher as considering job, and most of students considered teacher and major unconcerned job. Students considering major concerned job showed higher major satisfaction compared to students considering major unconcerned job. Career decision level was medium and there were not significant differences in career decision level by major, university, class standing, gender, considering job. Career decision level was affected positively by only general satisfaction in major.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.801-808
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• 2020

The purpose of the study is to find the factors that influence the financial leverage of Vietnam firms. The dependent variable is the financial leverage and the independent variables are firm size, asset structure, liquidity, growth opportunities, profitability, and firm age. The data are collected from Vietnam firms' annual financial reports in the period from 2010 to 2019. The study uses a sample of 448 Vietnam listed firms in the period. We also employ a panel regression model with pooled OLS and fixed effect to analyze the firms' financial data. The results of the model showed that financial leverage (FL) has a negative relationship with some factors such as asset structure (AS), liquidity (LQ), growth opportunities (GRW), profitability (ROA), and firm age (AGE) in the fixed effect regression. It means that when liquidity, profitability, and firm age increase, firms' financial leverage will decrease. While firms' financial leverage has still a positive relationship with the firm size (SIZE) in the model. As a result, when firm size increases, financial leverage will increase, too. The results showed that models are fit for the research and can be used to predict future findings. It is also useful for enterprises, financial advisors, investors, as well as the financial managers.

• Kyungpook Mathematical Journal
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• v.46 no.2
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• pp.297-305
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• 2006

We classify centroaffine minimal surfaces with constant curvature metric under some natural conditions on the cubic differentials.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.209-224
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• 2006

This paper presents an optimization model with performance constraints for two kinds of graph elements layout problem. The layout problem is partitioned into finite subproblems by using graph theory and group theory, such that each subproblem overcomes its on-off nature about optimal variable. Furthermore each subproblem is relaxed and the continuity about optimal variable doesn't change. We construct a min-max problem which is locally equivalent to the relaxed subproblem and develop the first order necessary and sufficient conditions for the relaxed subproblem by virtue of the min-max problem and the theories of convex analysis and nonsmooth optimization. The global optimal solution can be obtained through the first order optimality conditions.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.203-214
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• 2005

In this study the optimal control of fed-batch glycerol fermentation is investigated based on an impulsive dynamical system. Considering the sudden increase of the glycerol and alkali in fed-batch culture of biodissimilation of glycerol to 1,3-propanediol, this paper proposes a non-linear impulsive system of fed-batch culture. The existence, uniqueness and regularity properties of piecewise solution for the system are proved. In view of the controllability of volumes of glycerol added to the reactor instantaneously, the paper constructs an optimal control model based on the nonlinear impulsive system and the existence of the optimal control is obtained. The control variables here are the moments and the sizes of jumps in the states at the discrete instants and the objective is to maximize the productivity of 1,3-propanediol over one cycle.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.1-6
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• 2003

Associations, as specific forms of knowledge, reflect relationships among items in databases, and have been widely studied in the fields of knowledge discovery and data mining. Recent years have witnessed many efforts on discovering fuzzy associations, aimed at coping with fuzziness in knowledge representation and decision support processes. This paper focuses on associations of three kinds, namely, association rules, functional dependencies and pattern associations, and overviews major fuzzy logic extensions accordingly.

• The Pure and Applied Mathematics
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• v.24 no.4
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• pp.211-226
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• 2017

In this paper, machine learning models employed in various fields are discussed and applied to KOSPI200 stock index return forecasting. The results of hyperparameter analysis of the machine learning models are also reported and practical methods for each model are presented. As a result of the analysis, Support Vector Machine and Artificial Neural Network showed a better performance than k-Nearest Neighbor and Random Forest.

• The Pure and Applied Mathematics
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• v.24 no.4
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• pp.227-241
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• 2017

The study investigates the stock market using emotion index calculated from SMD based on investors' emotion. In the VAR anlaysis, we find that the correlation between the KOSPI200 return and emotion score sum is highest in 2- or 3- day lag. This study concludes that explanatory power of the SMD emotion index is limited in explaining the Korean stock market yet.

• Education of Primary School Mathematics
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• v.8 no.2 s.16
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• pp.69-96
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• 2004

The purpose of this study is to understand teaching and learning mathematics in elementary school classroom by considering mathematics as a kind of social practices and mathematics classroom as a kind of community of practice. The research questions of this study are as followings: 1) Which kinds of lesson organization reveal? 2) Which kinds of social participation structure reveal? 3) Which processes of making meaning reveal? This study was based on ethnomethodology. It was executed participation observations, interviews and surveys with teacher and 5 graders to collect the data related to the social practices formed their classroom. The social practices of mathematics classroom was analyzed from three aspects such as lesson organization, social participation structure and making meaning. The results from which we analyzed the social practices of the mathematics classroom are as followings. From the aspect of lessons organization, the teacher had a lot of power and authorities in the classroom and used them to elicitate students' responses. From the aspect of social participation structure, five SPSs(social participation structures) which revealed in Jo(1997)'s economics classrooms, were shown in this mathematics classroom, but there were a difference to the situations or frequencies which the SPSs appeared. From the aspect of making meaning, it was common that meanings are formed by the explanation of the teacher, but the teacher didn't deliver the mathematical meanings directly. She tried to interact with students to arrive shared meanings.

• Bulletin of the Korean Mathematical Society
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• v.53 no.1
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• pp.127-138
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• 2016

Differential subordination and superordination preserving properties for univalent functions in the open unit disk with an operator involving generalized Bessel functions are derived. Some particular cases involving trigonometric functions of our main results are also pointed out.