• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3583-3589
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• 2010

The semi-implicit scheme proposed by Backhaus is introduced to solve two-dimensional shallow water equation. This mothod is applied for the numerical model solving surface elevation and velocity field of Geum River estuary. For the verification of the method, numerical solutions by this model are compared with ones by Heap's well known explicit model. Solutions of two models resemble each other. The time-step chosen for the semi-implicit scheme turned out to be 3 to 6 times longer than explicit model depending on the stringent CFL criterion. The computation time could be reduced at least 50%. It was proved that this scheme is easy to handle dry banks which can be seen in Geum River estuary and numerical stability is obtained for long time computation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3797-3806
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• 2015

A population decline in rural area is correlated with the number of household, with agricultural workers, as a result, affects the farming income. Agricultural population is a foundation of agriculture structure. Agricultural population decline influences agricultural policies to be implemented for the future and there is concern about slowdown in productivity. The purpose of this study is to build the ability to use the model and conduct applied analyses of various kinds and to make rational agricultural policies by forecasting and analyzing agricultural population change. Unlike previous studies, which have some assumptions about the giving-up farming rate (GFR) of the key points on the agricultural population model or, After estimating only one equation with respect to the total population, and then distribute by sex and age. This study was conducted to investigate the reactions are different from the farmhouse, gender, age by estimating giving-up farming rate (GFR) equations each gender & age. Through this research, we can find that Farm Population changes of the simulation can be performed for a variety of agricultural policy in conjunction with existing agricultural simulation models as well.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.907-909
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• 2009

In this paper, the dependence of threshold voltage on the gate oxide thickness, which it mostly influenced on short channel effects in fabrication of FinFET, has been investigated. The transport model based on three dimensional Possion's equation has been used to analyze influence on gate oxide thickness. The gate oxide thickness is the most important factor to influence on the threshold voltage in nano structure FinFET. The potential distributions of this model are compared with those of three dimensional numerical simulation to verify this model. As a result, since potential model presented in this paper is good agreement with hree dimensional numerical model, the threshold voltage characteristics have been considered according to the gate oxide thickness of FinFET.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.228-237
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• 2018

The importance of eWOM (electronic word-of-mouth) communication through online communities is increasing on a daily basis. This study analyzed how the relationship between eWOM (electronic Word-Of-Mouth) factor and eWOM communication depends on the cultural orientation of users in the online community. The research model was developed based on four cultural orientations of individual affect Social tie and usefulness. The model consists of variables such as social tie and perceived usefulness as predecessors of eWOM, four dimensions of cultural orientation (Horizontal Individualism, Horizontal Collectivism, Vertical Individualism, Vertical Collectivism), and eWOM. The model was tested empirically using the PLS (partial least squares) structure equation model. Survey was conducted for online community users in South Korea. Data was statistically validated whether fits on research model. The study results reveal that Social Tie have a positive effect on Perceived Usefulness. Social Tie and Perceived Usefulness have a positive effect on eWOM. 3 of cultural orientations (HC, VI, VC) have a positive effect on Social Tie. Only one of cultural orientations (HC) have an negative effect on Perceived Usefulness. Especially, horizontal collectivism (HC) shows strong correlation with perceived usefulness, whereas vertical collectivism (VC) shows weak correlation with perceived usefulness andvertical individualism (VI) shows strongly correlation with social tie, whereas horizontal individualism (HI) shows weak correlation with social tie. Based on the study results, customized service strategy could be formulated according to the different vertical styles and various eWOM factors.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.129-142
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• 2016

This study evaluates the sectoral effects of the regeneration of the idle space and aims to analyze the impact relationship and structure with the quality of residents's life and local economy revitalization. this study verifies the 8 hypotheses from total 11 ones through the PLS structural equation model and suitability test for setting the hypothesis and statistical significance test. The results can be summarized into 3 parts. First, If physical, social and cultural aspects should be considered, Regeneration of idle space could meet the 2 pasts such as quality of residents life and local economy revitalization at the same time. Secondly, the regeneration of idle space from environmental aspect should be led by the local government and let it's effect leaded to local economy revitalization through the collaboration of private and public sector. Finally, it should promote the quality of resident's life and let the satisfaction linked to cyclical effects with local economy revitalization. This study has an significance that it provides the theoretical basis for regeneration of idle space and it is an empirical study for impact structure model.

• Culinary science and hospitality research
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• v.20 no.6
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• pp.1-12
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• 2014

This study was conducted by empirically analyzing the relation between effects of positive emotional response of female customers, who have at some point consumed food at Korean restaurants in Busan, and behavioral intention according to their food service consumption propensity. In order to achieve the objective of the study, the questionnaire survey was performed from March $10^{th}$ to $25^{th}$, and frequency analysis, confirmatory factor analysis, reliability analysis, correlation analysis, and SEM (structure equation model) were conducted by using SPSS 18.0 and AMOS for 248 questionnaires. As a result of an exploratory factor analysis, five factors were confirmed. In a confirmatory factor analysis, the average variance extracted (AVE) and composite reliability (CR) were confirmed as .508 to .665 and .905 to .946 respectively, which proved the convergent validity. In a hypothesis test, Hypothesis 1 was determined that the food service consumption propensity positively effects on emotional response. The results were as follows: the taste driven (${\beta}$=.325, t=3.907, p<.001), the health driven (${\beta}$=.190, t=2.688, p<.001), and the atmosphere driven (${\beta}$=.188, t=2.515, p<.001). Therefore, Hypothesis 1 was selected. Hypothesis 1 has determined that positive emotional response beneficially affects behavioral intention. As a result of an analysis, the standardized path coefficient was (${\beta}$=.496, t=6.388, p<.001), so Hypothesis 1 was selected. This result suggests that the taste driven factor has the biggest influence on emotional response in the food service consumption propensity for female customers, and food service business operators should strive to make a good restaurant atmosphere for customers to get positive emotional response (pleasure, comfort, satisfaction, and joy).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1075-1083
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• 2000

The prediction of the inelastic behavior of the structure is an essential part of reliability assessment procedure, because most of the failures are induced by the inelastic deformation, such as creep and plastic deformation. During decades, there has been much progress in understanding of the inelastic behavior of the materials and a lot of inelastic constitutive equations have been developed. These equations consist of the definition of inelastic strain and the evolution of the state variables introduced to quantify the irreversible processes occurred in the material. With respect to the definition of the inelastic strain, the inelastic constitutive models can be categorized into elastoplastic model, unified viscoplastic model and separated viscoplastic model and the different integration methods have been applied to each category. In the present investigation, the generalized integration method applicable for various types of constitutive equations is developed and implemented into ABAQUS by means of UMAT subroutine. The solution of the non-linear system of algebraic equations arising from time discretization with the generalized midpoint rule is determined using line-search technique in combination with Newton method. The strategy to control the time increment for the improvement of the accuracy of the numerical integration is proposed. Several numerical examples are considered to demonstrate the efficiency and applicability of the present method. The prediction of the inelastic behavior of the structure is an essential part of reliability assessment procedure, because most of the failures are induced by the inelastic deformation, such as creep and plastic deformation. During decades, there has been much progress in understanding of the inelastic behavior of the materials and a lot of inelastic constitutive equations have been developed. These equations consist of the definition of inelastic strain and the evolution of the state variables introduced to quantify the irreversible processes occurred in the material. With respect to the definition of the inelastic strain, the inelastic constitutive models can be categorized into elastoplastic model, unified viscoplastic model and separated viscoplastic model and the different integration methods have been applied to each category. In the present investigation, the generalized integration method applicable for various types of constitutive equations is developed and implemented into ABAQUS by means of UMAT subroutine. The solution of the non-linear system of algebraic equations arising from time discretization with the generalized midpoint rule is determined using line-search technique in combination with Newton method. The strategy to control the time increment for the improvement of the accuracy of the numerical integration is proposed. Several numerical examples are considered to demonstrate the efficiency and applicability of the present method.

• Journal of Navigation and Port Research
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• v.39 no.1
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• pp.69-75
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• 2015

The concrete purpose of this study is to suggest actually a debt ratio to optimize the capital structure providing a kind of approach to estimate the proper debt ratio with an analytical model and empirical data in Korean shipping industry. The mathematical and analytical model is started from the first equation about ROE, return of net operating income on equity, with an independent variable, debt ratio. It is constructed with several parameters, ROS(return of operating income on sales), TAT(total assets turnover), and NFCL(net finance cost to liabilities). There could not be a certain relationship between debt ratio and ROS or TAT, while some correlation or causality between debt ratio and NFCL. In other words, most of firms with high debt ratio is likely to burden higher finance cost than others with low one. In this case, there is a linearity relationship between debt ratio and NFCL, so then the second equation considering this relation could be included within the analytical approach of this paper. To be short, if the criteria of adequate debt ratio has to be defined as some level of debt ratio to optimize ROE, the ROE could be illustrated as a quadratic equation to debt ratio from two equations. Next, this research estimated those parameters' numbers through the single regression method with data over 12 years of Korean shipping industry, and identified empirically the fact that optimal debt ratio would be approximately 400%. To conclude, if that industry's sales and operating incomes are stable, the debt ratio could be accepted until twice of 200% had forced in order to guarantee its financial safety in past time.

• Journal of Wetlands Research
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• v.23 no.4
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• pp.277-286
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• 2021

This study compares the long-term hydrological cycles of the Seolmacheon and Cheongmicheon basin by applying the structural equation model (SEM). These two basins are found different especially in their land-use pattern. Both basins have the actual evapotranspiration data measured by the eddy-covariance method as well as the rainfall and runoff data. The length of the data considered in this study is nine years from 2010 to 2018. The structure of the SEM is determined by considering the correlations among the data as well as the general knowledge on the hydrological cycle. As a result, a total of three SEMs are applied sequentially to analyze their fittings. As irony would have it, two basins are found to be similar in the application of one SEM, but different in the application of another. Especially, when considering the feedback process between precipitation and evapotranspiration, two basins are found to be very different. That is, the feedback process between precipitation and evapotranspiration is found to be significant in the Cheongmicheon basin where the portion of agricultural area (i.e., paddy) is more than 40%.

• Journal of Korea Water Resources Association
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• v.43 no.3
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• pp.309-323
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• 2010

As climate changes and abnormal climates have drawn research interest recently, many countries utilize the GCM, which is based on SRES suggested by IPCC, to obtain more accurate forecast for future climate changes. Especially, many research attempts have been made to simulate localized geographical characteristics by using RCM with the high resolution data globally. To evaluate the impacts of climate and landuse change on water resources in the Han-river basin, we carried out the procedure consisting of the CA-Markov Chain, the Multi-Regression equation using two independent variables of temperature and rainfall, the downscaling technique based on the RegCM3 RCM, and SLURP. From the CA-Markov Chain, the future landuse change is forecasted and the future NDVI is predicted by the Multi-Regression equation. Also, RegCM3 RCM 50 sets were generated by the downscaling technique based on the RegCM3 RCM provided by KMA. With them, 90 year runoff scenarios whose period is from 2001 to 2090 are simulated for the Han-river basin by SLURP. Finally, the 90-year simulated monthly runoffs are compared with the historical monthly runoffs for each dam in the basin. At Paldang dam, the runoffs in September show higher increase than the ones in August which is due to the change of rainfall pattern in future. Additionally, after exploring the impact of the climate change on the structure of water circulation, we find that water management will become more difficult by the changes in the water circulation factors such as precipitation, evaporation, transpiration, and runoff in the Han-river basin.