• Smart Structures and Systems
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• v.20 no.6
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• pp.709-728
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• 2017

This disquisition proposes a nonlocal strain gradient beam theory for thermo-mechanical dynamic characteristics of embedded smart shear deformable curved piezoelectric nanobeams made of porous electro-elastic functionally graded materials by using an analytical method. Electro-elastic properties of embedded curved porous FG nanobeam are assumed to be temperature-dependent and vary through the thickness direction of beam according to the power-law which is modified to approximate material properties for even distributions of porosities. It is perceived that during manufacturing of functionally graded materials (FGMs) porosities and micro-voids can be occurred inside the material. Since variation of pores along the thickness direction influences the mechanical and physical properties, so in this study thermo-mechanical vibration analysis of curve FG piezoelectric nanobeam by considering the effect of these imperfections is performed. Nonlocal strain gradient elasticity theory is utilized to consider the size effects in which the stress for not only the nonlocal stress field but also the strain gradients stress field. The governing equations and related boundary condition of embedded smart curved porous FG nanobeam subjected to thermal and electric field are derived via the energy method based on Timoshenko beam theory. An analytical Navier solution procedure is utilized to achieve the natural frequencies of porous FG curved piezoelectric nanobeam resting on Winkler and Pasternak foundation. The results for simpler states are confirmed with known data in the literature. The effects of various parameters such as nonlocality parameter, electric voltage, coefficient of porosity, elastic foundation parameters, thermal effect, gradient index, strain gradient, elastic opening angle and slenderness ratio on the natural frequency of embedded curved FG porous piezoelectric nanobeam are successfully discussed. It is concluded that these parameters play important roles on the dynamic behavior of porous FG curved nanobeam. Presented numerical results can serve as benchmarks for future analyses of curve FG nanobeam with porosity phases.

• Advances in nano research
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• v.5 no.4
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• pp.281-301
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• 2017

In this disquisition, an exact solution method is developed for analyzing the vibration characteristics of magneto-electro-elastic functionally graded (MEE-FG) beams by considering porosity distribution and various boundary conditions via a four-variable shear deformation refined beam theory for the first time. Magneto-electroelastic properties of porous FG beam are supposed to vary through the thickness direction and are modeled via modified power-law rule which is formulated using the concept of even and uneven porosity distributions. Porosities possibly occurring inside functionally graded materials (FGMs) during fabrication because of technical problem that lead to creation micro-voids in FG materials. So, it is necessary to consider the effect of porosities on the vibration behavior of MEE-FG beam in the present study. The governing differential equations and related boundary conditions of porous MEE-FG beam subjected to physical field are derived by Hamilton's principle based on a four-variable tangential-exponential refined theory which avoids the use of shear correction factor. An analytical solution procedure is used to achieve the natural frequencies of porous-FG beam supposed to magneto-electrical field which satisfies various boundary conditions. A parametric study is led to carry out the effects of material graduation exponent, porosity parameter, external magnetic potential, external electric voltage, slenderness ratio and various boundary conditions on dimensionless frequencies of porous MEE-FG beam. It is concluded that these parameters play noticeable roles on the vibration behavior of MEE-FG beam with porosities. Presented numerical results can be applied as benchmarks for future design of MEE-FG structures with porosity phases.

• Fashion & Textile Research Journal
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• v.25 no.2
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• pp.175-184
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• 2023

This study explores aspects of Vietnamese students' acculturation and acceptance behavior of K-fashion, based on the theory of planned behavior (TPB). In-depth interviews were conducted with 8 Vietnamese international students in Korea. The results of the study firstly indicate that K-fashion acceptance behavior of Vietnamese students reflected eight values of K-fashion, two motives of behavior, and two types of K-fashion acceptance behavior. Vietnamese students generally displayed a favorable attitude toward K-fashion. They all switched to K-fashion styles and actively showed their styles through SNS. Second, there was a difference in K-fashion behavior depending on whether the motivation for acculturation was of an active or inactive nature. The distinction between these two groups was determined by applying behavioral reasoning theory (BRT). Students whose motivation for learning Korean was an interest in Korean culture were characterized by active behavior in adapting to Korean culture, while those whose motivation for learning Korean was for strategic reasons, such as finding a good job, exhibited inactive K-fashion acceptance. This study has academic significance in that it enhances the understanding of Vietnamese consumers through the K-fashion acceptance behavior of Vietnamese students in Korea. Vietnamese students who actively embrace K-fashion play an important role in spreading K-fashion, so it could be beneficial to establish a strategy for promoting K-fashion in collaboration with them.

• Journal of the Korea Society of Computer and Information
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• v.14 no.11
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• pp.159-167
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• 2009

The vehicles play a significant role in modern people's life as economy grows. The development of car navigation system(CNS) provides various convenience because it shows the driver where they are and how to get to the destination from the point of source. However, the existing map-based CNS does not consider any environments such as traffic congestion. Given the same starting point and destination, the system always provides the same route and the required time. This paper proposes a path planning method with traffic prediction by applying historical driving information to the Fuzzy theory and Bayesian update. Fuzzy theory classifies the historical driving information into groups of leaving time and speed rate, and the traffic condition of each time zone is calculated by Bayesian update. An ellipse area including starting and destination points is restricted in order to reduce the calculation time. The accuracy and practicality of the proposed scheme are verified by several experiments and comparisons with real navigation.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.3
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• pp.253-261
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• 2004

Game theory is mathematical analysis developed to study involved in making decisions. In 1928, Von Neumann proved that every two-person, zero-sum game with finitely many pure strategies for each player is deterministic. As well, in the early 50's, Nash presented another concept as the basis for a generalization of Von Neumann's theorem. Another central achievement of game theory is the introduction of evolutionary game theory, by which agents can play optimal strategies in the absence of rationality. Not the rationality but through the process of Darwinian selection, a population of agents can evolve to an Evolutionary Stable Strategy (ESS) introduced by Maynard Smith. Keeping pace with these game theoretical studies, the first computer simulation of co-evolution was tried out by Hillis in 1991. Moreover, Kauffman proposed NK model to analyze co-evolutionary dynamics between different species. He showed how co-evolutionary phenomenon reaches static states and that these states are Nash equilibrium or ESS introduced in game theory. Since the studies about co-evolutionary phenomenon were started, however many other researchers have developed co-evolutionary algorithms, in this paper we propose Game theory based Co-Evolutionary Algorithm (GCEA) and confirm that this algorithm can be a solution of evolutionary problems by searching the ESS.To evaluate newly designed GCEA approach, we solve several test Multi-objective Optimization Problems (MOPs). From the results of these evaluations, we confirm that evolutionary game can be embodied by co-evolutionary algorithm and analyze optimization performance of GCEA by comparing experimental results using GCEA with the results using other evolutionary optimization algorithms.

• 사회경제평론
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• v.29 no.1
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• pp.119-154
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• 2016

Kalecki thought that monetary and financial factors play very important roles in the processes of investment decision and expenditure. He also acknowledged that interest rate is monetary phenomenon and investment finance is provided by banks prior to savings as Keynes did, and suggested that the more is the debt, the greater is the risk of debtor and lender. However, in developing investment theory he dismissed those monetary and financial factors or substituted into actual profit or savings, because he aimed to construct the investment theory to be able to explain the 'automatic mechanism of the fluctuation of capitalist economy'. Thus it is argued that Kalecki did not consider the monetary and financial factors in his investment theory. This paper aims to modify Kalecki's investment theory so that it incorporates the monetary and financial factors, such as the willingness of banking system to lend, interest rates, the ratio of leverage which had been dismissed by him. The Kaleckian investment theory that incorporates the monetary and financial factors in Kalecki's theory of investment allows us to explain not only an automatic and regular business cycle, but also irregular excessive investment and high leverage, consequent risk increase and financial crisis occurred in the economy with developed financial system.

• The Journal of Information Systems
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• v.29 no.3
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• pp.53-75
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• 2020

Purpose Despite the continued rise in the popularity of mobile MMORPGs, the previous studies mainly focused on negative results of playing MMORPG such as violence and game addiction. In addition, previous studies that verified game play motives were not enough to explain user's fundamental motives for MMORPG play. To verify the positive role of playing MMORPG, this study focused on stress coping strategies on continued play MMORPG, and divided factors into two dimensions: escapism and coping with system. The purpose of this study is to comprehensively identify the discriminatory effects of each factor on users' self-control, and the effect of self-constrol and behavioral adapatation on continued use intention for MMORPG. Design/methodology/approach This study was designed to examine the structural relationships among MMORPG users' escapism, system coping, self-control, behavioral adaptation and continued use intention for MMORPG. Findings The results from this study are as follow. First, the participants' effect-based escapism had a positive impact on self-control, whereas cause-based escapism had a negative impact on self-control. Next, proactive coping and reactive coping for system problem had a positive impact on self-control. In addition, Self-control had a positive impact on behavioral adaptation and continued use intention for MMORPG. Lastly, the behavioral adaptation to MMORPG had a positive impact continued use intention. The results of our study can suggest the positive effects of coping strategy on users' self-control and behavioral adaptation by applying the theory of both escapism and coping with system. Based on our results, game companies should develop contents that can gratify users' coping motives and enhance self-control and behavioral adaptation.

• Korean Journal of Childcare and Education
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• v.10 no.2
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• pp.133-151
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• 2014

The purpose of this study was to examine maternal mental-state talks while mothers and their 2-year-old children interacted in two contexts which were pretense/role-play and shared book reading contexts. Thirty-six dyads of mothers and their 2-year-old children participated in this study. The results showed that the mothers made more references to mental-state in the pretense/role-ply context than in the book reading context, but the ratio of using the three types of mental state talks(i.e., desire, feeling, and cognition) did not vary with the contexts. The most frequently used mental-state talk by the mothers was 'desire' in both contexts and the tendency to use the three types of mental-state talks in the two contexts was related. The results of this study suggest implications for providing useful information on the role of mothers in the development of children's theory of mind.

• (The) Research of the performance art and culture
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• no.37
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• pp.223-247
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• 2018

A reading aloud performance is an activity in which the actors convey the meaning of the play to the audience through reading the play without memorizing the play. Although this term has been used for a long time, it can be said in the early 2000s that Korea began to pay attention to reading aloud performance in the cultural world. As the theater education is strengthened in the 2015 revision curriculum, interest in this "reading aloud performance" is also growing. In this article, we analyzed the reading aloud performance of the 8th contemporary Japanese drama '2018' in order to utilize the reading aloud performance in the educational field and to utilize it in the lecture of the children education. There are two types of rehearsals for the actors on stage: 'Reading by watching drama', 'Playing by memorizing drama', and 'Mixing two types'. In the end, the key is that there is no set rule for the type of reading aloud performance. It's not trouble to see or not to see the play. It is not necessary to have a stereotype that you should do a proper reading aloud performance in consideration of your situation, but that you should do this. If children understand the concept of read aloud performance in a flexible way, the educational effect will be greater. Based on this analysis, we suggested 'not sticking to the form of reading aloud performance' and 'choosing various types of reading aloud performance' as a criterion for applying to the education field for children. In addition, the sub-criteria required for selecting 'various types of lecture performances' include' selecting a specific scene in the content of the play ',' considering the level or situation of the student ',' not hesitating to make a new type of lecture performance '. I hope that this article will be a stepping stone to revitalize the discussion in the educational world where discussion on the performance of reading aloud is requested, and to solve the problem of lack of educational design due to lack of theory.

• Korean Journal of Social Welfare
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• v.58 no.1
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• pp.59-85
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• 2006

The purpose of this study was to identify how traumatic experiences and stresses caused hopelessness and depression among low-income residents, and to delineate what social problem solving capabilities might play roles in relation to the hopelessness theory of depression. For the purpose of the study, the target group of this study was restricted to adults over 20. This study recruited 175 low-income residents(the Beneficiary of National Basic Livelihood Security Act and the Near Poor Group) in Busan, Korea and employed a self-administered survey method during February, 2004. The following are the major results of the study. First, in low-income subjects, stresses showed positive influences on hopelessness. Second, in low-income subjects, stresses and hopelessness showed positive influences on depression. Third, stress influenced depression with hopelessness as the intervening variable, but it was not statistically significant path in traumatic experiences. The hopelessness theory of depression is to test whether the individuals who have negative attributional style and experience negative life events are likely to make negative attributions for the negative events they confront. The present study, using low-income residents, found that negative life experience predict negative attributions without negative attributional style. Fourth, social problem solving capabilities buffered the relationship between stress and hopelessness. It was also significant subscales apart from Positive Problem Orientation and Negative Problem Orientation. Fifth, social problem solving capabilities buffered the relationship between hopelessness and depression. It was also significant subscales apart from Negative Problem Orientation and Impulsivity/Carelessness Style. Based on the results, practice implications by identifying what social problem solving capabilities might play roles in hopelessness theory of depression were discussed.