• Journal of Korea Water Resources Association
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• v.37 no.9
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• pp.719-727
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• 2004

Water quality models can be applied to manage the regional water quality problems and to estimate the target and allowable pollution load in watershed effectively. The optimization of state variables in the given water quality model Is necessary to build up more effective model. The least-squares method is applied to fit field observations in QUAL2E developed by U.S. EPA, which is most widely used one in the world to simulate the stream water quality, and the optimization model with constraints is constructed to estimate the parameters. The objective function of the optimization model is solved by Solver in Microsoft Excel and Monte Carlo simulation is conducted to know the influence of parameter in conventional pollutants. It is found that this technique is easily implemented and rapidly convergent computational procedure to calibrate the parameters after appling this approach in Anyang stream located in Kyonggi province mainly.

• Journal of The Korean Association of Information Education
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• v.21 no.6
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• pp.639-646
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• 2017

As computational thinking(CT) is gaining focus as a key 21st century skill much attention has been paid to promoting CT through software education. However, more studies are needed to design and implement effective CT assessment methods. This study aims to investigate the effects of three CT assessment methods in a course designed to enhance CT competencies of 52 pre-service teachers with a non-computer science background during one semester. To analyze pre-service teachers' CT competencies, we used 3 CT assessment methods: (1) pre-and post-testing based on Bebras computational thinking challenge questions, (2) Dr. Scratch to analyze group scratch projects automatically, and (3) scratch exam designed in this study to evaluate the development of CT. Our results show the positive effects of integrating assessment methods for promoting CT competencies. We end this paper with the discussion of advantages and implications of this integration.

• Journal of the Korea Convergence Society
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• v.7 no.5
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• pp.213-219
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• 2016

This paper presents a branch-and-bound algorithm for solving the concave minimization problem with upper bounded variables whose single constraint is linear. The algorithm uses simplex as partition element. Because the convex envelope which most tightly underestimates the concave function on the simplex is uniquely determined by solving the related linear equations. Every branching process generates two subsimplices one lower dimensional than the candidate simplex by adding 0 and upper bound constraints. Subsequently the feasible points are partitioned into two sets. During the bounding process, the linear programming problems defined over subsimplices are minimized to calculate the lower bound and to update the incumbent. Consequently the simplices which do certainly not contain the global minimum are excluded from consideration. The major advantage of the algorithm is that the subproblems are defined on the one less dimensinal space. It means that the amount of work required for the subproblem decreases whenever the branching occurs. Our approach can be applied to solving the concave minimization problems under knapsack type constraints.

• Journal of the Korea Convergence Society
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• v.8 no.10
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• pp.257-271
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• 2017

In this study, phenomenological methodology was used to understand the experience of family management style in mothers who have children with atopic dermatitis. For study methods, in-depth interview was conducted on 9 mothers residing in Seoul and the approach from phenomenological methodology by Colaizzi was used. As a result, 69 significant statements were deduced as well as 21 themes, 10 theme clusters, and 4 categories. These main categories include experiences of accepting atopic dermatitis as a reality, family management style for overcoming atopic dermatitis, reality of facing chronic fatigue, and hope and expectation for the child's health. Our study show that the intervention for improving family management style regarding atopic dermatitis is required including the enhancement of the mothers' quality of life and the recovery of family relationship.

• Journal of the Korea Convergence Society
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• v.8 no.10
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• pp.351-358
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• 2017

This study analyzed the process of mourning for aging in the film 'Miss Granny' in a convergent method. In exploring the contents of the movie repeatedly and interpreting the feeling of loss of old age in aging process as mourning process, I explored them in a psychoanalytic way. In other words, in a psychoanalytic method, I analyzed the aging process as a process of reinterpreting life and the change in developmental attitude toward the future life as a psychological world of mourning. The results of the study show that the process of mourning follows 'loss and deficiency', 'escape and regression', 'disidentification and decentralization', and 'adaptation to the new reality'. Based on these results, this research suggests that the counselor should not only focus on creating a psychological mood environment so that the client's mourning work will be smooth, but also should be able to use a complex counseling technique to improve the mental ability of the client.

• Journal of the Korea Convergence Society
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• v.8 no.10
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• pp.115-124
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• 2017

The purpose of the study was to investigate the convergence factors to posttraumatic growth(PTG) in survivors with female urogenital neoplasm survivors. A self-reported questionnaire was completed by 141 female urogenital neoplasm survivors via e-mail from September to October, 2016. The questionnaire consisted of PTG inventory, illness intrusiveness rating scale, cancer coping, family cohesion evaluation scale, and medical outcomes study social support survey. The data were analyzed by ANOVA, Pearson-correlation coefficient, and multiple regression analysis. Total score of PTG was 84.13points and statistically significant according to age, religion, marital status and positively associated with coping, family cohesion and social support. Results of the regression analysis showed religion(${\beta}=.127$), marital status(${\beta}=.081$), coping(${\beta}=.232$) and family cohesion(${\beta}=.415$), it were explained 44.7%. This study indicates that it is important to understand general characteristics of personal. And a convergent approach is needed to promote PTG by hospital and community.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1768-1789
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• 2015

The maximal signal-to-interference-plus-noise ratio (Max-SINR) algorithm for interference alignment (IA) has received considerable attention for its high sum rate achievement in the multiple-input multiple-output (MIMO) interference channel. However, its complexity may increase dramatically when the number of users approaches the IA feasibility bound, and the number of iterations and computational time may become unacceptable. In this paper, we study the properties of the Max-SINR algorithm thoroughly by presenting theoretical insight into the algorithm and by providing the potential of reducing the overall computational cost. Furthermore, a novel IA algorithm based on the principle direction search is proposed, which can converge more rapidly than the conventional Max-SINR method. In the proposed algorithm, it searches along the principle direction, which is found to approximately point to the convergence values, and can approach the convergence solutions rapidly. In addition, the closed-form solution of the optimal step size can be formulated in the sense of minimal interference leakage. Simulation results demonstrate that the proposed algorithm outperforms the conventional minimal interference leakage and Max-SINR algorithms in terms of the convergence rate while guaranteeing the high throughput of IA networks.

• Structural Engineering and Mechanics
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• v.43 no.5
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• pp.691-709
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• 2012

This paper provides a variety of viewpoints to illustrate the mechanism of the deck-stay interaction with the appropriate initial shapes of cable-stayed bridges. Based on the smooth and convergent bridge shapes obtained by the initial shape analysis, the one-element cable system (OECS) and multi-element cable system (MECS) models of the Kao Ping Hsi Bridge in Taiwan are developed to verify the applicability of the analytical model and numerical formulation from the field observations in the authors' previous work. For this purpose, the modal analysis of the two finite element models are conducted to calculate the natural frequency and normalized mode shape of the individual modes of the bridge. The modal coupling assessment is also performed to obtain the generalized mass ratios among the structural components for each mode of the bridge. The findings indicate that the coupled modes are attributed to the frequency loci veering and mode localization when the "pure" deck-tower frequency and the "pure" stay cable frequency approach one another, implying that the mode shapes of such coupled modes are simply different from those of the deck-tower system or stay cables alone. The distribution of the generalized mass ratios between the deck-tower system and stay cables are useful indices for quantitatively assessing the degree of coupling for each mode. These results are demonstrated to fully understand the mechanism of the deck-stay interaction with the appropriate initial shapes of cable-stayed bridges.

• Macromolecular Research
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• v.12 no.5
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• pp.528-533
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• 2004

We have prepared amide dendrons having alkyl peripheral units and various focal moieties through a convergent synthetic approach. The amphiphilic properties, due to hydrophilic amide branches and the hydrophobic peripheral units, provide an opportunity for the amide dendrons to self-organize in water. The dendritic architecture itself is also one of the critical factors in the self-organization of the amide dendrons in water. In particular, function-alization was performed at the focal point to elucidate the relationship between the focal functionality and the self-organized structures of the dendritic building blocks in the aqueous phase. The dendron having a short poly(ethylene glycol) monomethyl ether (MeO-PEG) unit (M$\_$n/ =750) as the focal moiety formed a vesicular organization in water. As the size of the hydrophilic focal MeO-PEG increased to M$\_$n/ =2,000 and 5,000, the self-organized structures became rod-type and spherical micelles, respectively. Our observation of multiple morphologies for amide dendrons is in good agreement with previous reports that indicated that the micellar structures changed from vesicles to rod-types and then to spheres upon increasing the size of the hydrophilic moiety of the amphiphiles.

• Journal of the Korea Convergence Society
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• v.8 no.3
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• pp.225-235
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• 2017

Firms employ one of two stock repurchasing methods, either direct open market repurchase or indirect repurchase through trust contracts. Since these two methods have some regulatory differences, managers of firms may use a repurchasing method as a signal to convey the information to the market. Therefore, this study investigates the relationship between stock repurchasing methods and implied cost of equity of firms. The results show that there is a significant and negative relationship between stock repurchase announcement and cost of equity. In addition, the implied cost of equity for firms employing direct open market repurchase is significantly lower than those of firms that use indirect repurchase method. Overall, the market accurately reflects the information conveyed by two stock repurchasing methods into cost of equity of firms.