• Journal of Korean Society of Steel Construction
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• v.18 no.6
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• pp.717-726
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• 2006

Traditional external post-tensioning method using either steel bars or tendons is commonly used as a retrofitting method for steel composite bridges. However, the method has some disadvantages such as stress concentration at anchorages and inefficient load-carrying capability of live loads. Multi-stepwise prestressing method using thermal expanded coverplate is a newly proposed prestressing method, which was originally developed for prestressing steel structures. A new retrofitting method for steel girder bridges founded on a simple concept of thermal expansion and contraction of cover plate, the method is a hybrid of and combines the advantages of external post-tensioning and thermal prestressing. In this paper, basic concepts of the method are presented and an illustrative experiment is introduced. From actual experimental data, the thermal prestressing effect was substantiated and the FEM approach for its analysis was verified. The retrofitting effects ofa single-span bridge were analyzed and the feasibility of the developed method was examined.

• Journal of Forest and Environmental Science
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• v.24 no.3
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• pp.155-158
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• 2008

Site index is the essential tool for forest management to estimate the productivity of forest land Generally, site index equation is developed and used by relationship between stand age and dominant tree heights. However, there is a limit to use the site index equation in the application of variable ages, environmental influence, and estimation of site index for unstocked land. Therefore, it was attempted to develop a new site index equations based on various environmental factors including site and topographical variables. This study was conducted to develop regional site index equations based on the relationship between site index and soil factors for Pinus densiflora. Environmental factors that obtained from GIS application, were selected by stepwise-regression. Site index Equation was estimated by multiple regression from selected factors. Four environmental factors were selected in the final site index equations by stepwise regression. It was observed that coefficients of determination for site index equations were ranged from 0.34 which seem to be relatively low but good enough for estimation of forest stand productivity. The site index equations developed in this study were also verified to be useful by three evaluation statistics such as model's estimation bias, model's precision and mean square error type of measure.

• Journal of KIISE:Software and Applications
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• v.41 no.8
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• pp.598-604
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• 2014

In this paper, we develop stepwise regression data envelopment model to select important variables. We formulate null hypothesis to understand the importance of each variable and use Kruskal-Wallis test for this purpose. If the Kruskal-Wallis test does reject the null hypothesis this will imply there is significant fluctuation in the efficiency score relative to base model. And therefore we have to further check the pair of variables that causes the fluctuation in order to determine its importance using Conover-Inman test. The proposed models helps understand the extent of misclassification decision making units as efficient/inefficient when variables are retained or discarded alongside provides useful managerial prescription to make improvement strategies.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.4
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• pp.574-579
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• 2009

There have been much difficulties to construct an optimized neural network in complex nonlinear regression problems such as selecting the networks structure and avoiding overtraining problem generated by noise. In this paper, we propose a stepwise constructive method for neural networks using a flexible incremental algorithm. When the hidden nodes are added, the flexible incremental algorithm adaptively controls the number of hidden nodes by a validation dataset for minimizing the prediction residual error. Here, the ELM (Extreme Learning Machine) was used for fast training. The proposed neural network can be an universal approximator without user intervene in the training process, but also it has faster training and smaller number of hidden nodes. From the experimental results with various benchmark datasets, the proposed method shows better performance for real-world regression problems than previous methods.

• Journal of Korean Society of Rural Planning
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• v.19 no.4
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• pp.269-281
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• 2013

The purpose of this study is to examine the effects of the rural community planning focusing on the stepwise empowerment system in Jinan-gun, Jeollabuk-do province. This paper also tries to examine how this system affect the awareness for community planning and empowerment of the residents. The satisfaction of the people who join this program were also investigated. The subjects of the research were divided into two groups. Group A consisted of the people who join the system from the first stage, and group B consisted of the people who joined the fourth stage directly. The differences of the recognition, capability changes and satisfaction between two groups were compared and analyzed by questionnaires. The results of this research can be summarized as follows. The first, group A recognized the community planning system in Jinan-gun more positively than group B. They thought that it's very useful and beneficial for their community and this system should be continued further. The second, group A considered that they achieved bigger advancement in community design capabilities in terms of personal, relational and social aspects than group B. In addition, group A also showed higher satisfaction for rural community planning than group B. Based on the results, alternatives for rural community planning were drawn as follows. The first, considering that group A showed more positive responses, starting from the first stage is more stable way to succeed in rural community planning. Which means the critical condition of community design is not the community business but the improving the public awareness and community mind. The second, it's considered that the number of participation is proportional to the advancement of capability in community project, so improving residents' opportunity to participation in community design might be effective. The third, community leader is another critical condition. It is needed to pay more attention to the education for the rural community leader with good experience and capability of community affairs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.10
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• pp.1305-1313
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• 2013

In this study, a method to apply feature-based simplification to boundary representation models is proposed. For feature-based simplification, a volume decomposition tree is created from a boundary representation model. The volume decomposition tree is represented by regularized Boolean operations of additive volumes, subtractive volumes, and fillet/round/chamfer volumes, and it is generated by stepwise volume decomposition, which consists of fillet/round/chamfer decomposition, wrap-around decomposition, volume split decomposition, and cell-based decomposition. After the volume decomposition tree is transformed to an infix expression, the CAD model can be simplified by reordering the volumes. To verify the proposed method, a prototype system was implemented, and experiments on test cases were conducted. From the results of the experiments, it is verified that the proposed method is useful for simplifying CAD models based on boundary representation.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.4
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• pp.53-60
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• 2009

Recently, the Korean government has amended the "National Territory Planning Act" by adding criteria to designate the Impact Fee Zone on the basis of the population increase rate. Taking the Dongtan Newtown in Hwasung City as the case, the study first tries to apply a grid analysis method to figure out the cells that exceed the legal population increase rate criteria. Then, the study, for rather a practical purpose, introduces a scenario analysis that tries to envelope the cells into a spatially contiguous groups based on their degrees of stepwise adjacency by cell buffer formation. By overlapping the selected cell groups chosen by such stepwise scenarios over the actual zoning map of land-uses for the vicinity, it seems clear that the chosen areas rationally coincide with those residential blocks and commercial areas with the high population density in the Newtown.

• The Journal of the Korea Contents Association
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• v.15 no.3
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• pp.219-228
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• 2015

The purpose of this study was to examine the relationships between anger expression, social supports, and adjustment to college life among nursing students. A convenience sample of 266 students in two colleges participated in the study. Data were analyzed using t-tests, ANOVA, Pearson correlation coefficients, and multiple stepwise regression. The mean score for adjustment to college life was above average. The mean score for adjustment to college life differed significantly according to students' reasons for applying to college and perceived health status. Adjustment to college life significantly correlated with anger expression and social supports. Multiple stepwise regression analysis showed that anger expression (Anger-Out, Anger-In, and Anger-Control), social supports, and perceived health status explained 27.1% of the variance in adjustment to college life. The study findings suggest that interventions intended to promote nursing students' adjustment to college life should focus on improving anger management, social supports, and perceived health status.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.597-605
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• 2016

This study aimed to examine the multiple factors to affect the health conservation in the middle aged women. The subjects were 143 middle aged women from 40 to 59 years old and the data collection period was from June 1 to 25, 2016. The data was analyzed by descriptive statistics, t-test, ANOVA, Pearson's correlation coefficients, and stepwise multiple regression. We found a significantly positive association between health conservation and health promotion behaviors among middle-aged women. However, menopausal symptoms and wisdom were not significantly associated with health conservation. Stepwise multiple regression analysis was performed to analyze the most correlation variables were health enhancement behaviors with 12.5% and existence of spouse with 3.2%. This study provides more ensured fundamental data for the health conservation and enhancement in the middle aged women.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.2
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• pp.67-82
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• 2014

The purpose of this study is two-fold : the one is to examine the causal relationship between domestic large firms' win-win growth effort and their financial performance by fiscal years; and the other is to develop a quantitative win-win growth index to overcome the limitation of the current one mainly using a survey method developed by NCCP (National Commission for Corporate Partnership). To serve the first purpose, we take a sample of 128 large companies whose win-win growth indices as of year 2011 and 2012 were evaluated by NCCP. We use their respective fiscal year's financial data to select 62 candidate financial ratios, which are then used in subsequent empirical tests. For the tests, we employ ordered probit model with stepwise selection method and two-way ANOVA with randomized block design to identify which of the 62 financial ratios are statistically significant ones to affect the firms' win-win growth index as well as to determine if the firms' win-win growth effort would cause their financial performance positively. To serve the second purpose, we devise a model using the 123 firms' 45 financial ratios, which employs ordered probit model with stepwise selection, and the validation of the model follows. We claim that the model suggested in this study serve as an alternative complementing the current one as it can produce the index in a more objective and swift manner using the firms' publicized financial statements.