• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.29-41
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• 2017

Design rainfalls are one of the most important hydrologic data for river management, hydraulic structure design and risk analysis. The design rainfalls are first estimated by a point frequency analysis and the IDF (intensity-duration-frequency) curve is then constructed by a nonlinear regression to either interpolate or extrapolate the design rainfalls for other durations which are not used in the frequency analysis. It has been widely recognised that the more reliable approaches are required to better account for uncertainties associated with the model parameters under circumstances where limited hydrologic data are available for the watershed of interest. For these reasons, this study developed a hierarchical Bayesian based GLM (generalized linear model) for a regional frequency analysis in conjunction with a scaling function of the parameters in probability distribution. The proposed model provided a reliable estimation of a set of parameters for each individual station, as well as offered a regional estimate of the parameters, which allow us to have a regional IDF curve. Overall, we expected the proposed model can be used for different aspects of water resources planning at various stages and in addition for the ungaged basin.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1195-1203
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• 2014

Since IFC (Industry Foundation Classes) 4 is based on the representation of 3D elements for an architecture project, and does not define standardized shapes for civil projects such as roads, bridges, and tunnels etc, it has limitations in securing interoperability for exchanging a shape information model for the civil projects. Besides, since road facilities have a linear reference, which is modeled along the center alignment, it is difficult the designers to create a standardized 3D road model. The aim of this study is to configure structure elements and their attribute for a road in the perspective of 3D design for developing a shape information model for the road. To solve these issues, this study analyzes the design documents, which consist of a road design handbook, guide, specifications and standards, and then extract shape elements and their attributes of road structures. Such shape elements are defined as an entity item and we review a hierarchical structure of a road shape defined by a virtual road model. The detailed elements and their attributes can be utilized as a 3D shape information model for constructing BIM (Building Information Modeling) environment for Infrastructures. Besides, it is expected that the suggested items will be utilized as a base data for extending to IFC for a road subdividing the detailed shapes, types and attributes for road projects.

• Journal of the Korean School Mathematics Society
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• v.17 no.1
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• pp.23-43
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• 2014

This study aims to develop strategies for improving the affective characteristics of Korean students based on results from international achievement tests. In pursuing the goal, different research methods are employed including a) analysis of the theories and literature regarding the affective domains included in PISA and TIMSS studies; b) analysis of the current situation and needs of Korean students with respect to the affective factors based on PISA and TIMSS results; c) case studies of best practices in relation to students' affective domains in Korea and abroad; and d) development of strategies for improving and supporting Korean students' affective characteristics. Especially, this paper describes meta-analyses of the results from the previous PISA and TIMSS studies. Afterwards, it reports statistical analyses results on the relationship between students' affective achievements and educational context variables. Data from TIMSS 2011, TIMSS 2007, PISA 2006, and PISA 2003 are used for the analyses, and contextual variables are selected through rigorous statistical analyses including frequency and correlation, and expert consultation. The effects of educational contextual variables on students' affective achievement in mathematics and science are analyzed through Hierarchical Linear Model.

• Journal of Communications and Networks
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• v.18 no.5
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• pp.784-795
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• 2016

In this paper, we investigate the resource allocation problem in time-varying heterogeneous wireless networks (HetNet) with multi-homing user equipments (UE). The stochastic optimization model is employed to maximize the network utility, which is defined as the difference between the HetNet's throughput and the total energy consumption cost. In harmony with the hierarchical architecture of HetNet, the problem of stochastic optimization of resource allocation is decomposed into two subproblems by the Lyapunov optimization theory, associated with the flow control in transport layer and the power allocation in physical (PHY) layer, respectively. For avoiding the signaling overhead, outdated dynamic information, and scalability issues, the distributed resource allocation method is developed for solving the two subproblems based on the primal-dual decomposition theory. After that, the adaptive resource allocation algorithm is developed to accommodate the timevarying wireless network only according to the current network state information, i.e. the queue state information (QSI) at radio access networks (RAN) and the channel state information (CSI) of RANs-UE links. The tradeoff between network utility and delay is derived, where the increase of delay is approximately linear in V and the increase of network utility is at the speed of 1/V with a control parameter V. Extensive simulations are presented to show the effectiveness of our proposed scheme.

• Journal of Engineering Education Research
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• v.18 no.1
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• pp.61-73
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• 2015

The purpose of this study is to suggest some direction to support learning of students in college of engineering. It results from the assumption that engineering education accreditation should come with assessment of the educational process. To analyze the learning process, this study analyzed 5 categories - involvement in and out of instruction, faculty-student interaction, teaching-learning outcomes, and the system of student support. The Research method was questionnaire, and T-test and hierarchical linear model were used. The major findings are as follows. Major-level of satisfaction in teaching-learning and optional-level of satisfaction in teaching-learning are good. But the degree of self-directed learning activities and student-faculty interaction is low, and writing attitude and learning outcomes are not good. Student-faculty interaction, high-order thinking activities and active involvement have a good influence on learning outcomes. So this study suggests to enhance active involvement in instruction, high-order thinking activities, writing skills, and interaction with faculty for the improvement of quality of higher education.

• Korean Journal of Social Welfare
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• v.66 no.1
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• pp.35-59
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• 2014

The purpose of this study is to investigate determinants of the saving behaviors, perceptions of economic situation and attitudes on the program of the Individual Development Account program participants in Korea. Data used for this article was the survey on the participants of 'Seoul Hope-plus Saving Account Program' implemented by Seoul Welfare Foundation for 3 years. In order to consider variances within-individual and between-individuals, Hierarchical Linear model is used for this study. The results are as follows. First, In demographic factors, disability, gender, education level, marriage status are significant factors on the effectiveness of the program. Second, the participation on the program has positive effects on the conception on the living standard and economic status of the participants. However, total amount of savings excluding savings on 'Hope plus' has decreased. The household income is positively related with the amount of savings. Thus, it is necessary to consider individuals' socio-demographic factors to planning the asset-based program.

• Journal of the Korean Data and Information Science Society
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• v.22 no.2
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• pp.137-148
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• 2011

In this paper, we systematically investigate regional differences of the dead due to injuries in cities, towns and counties about transportation accidents, suicides and fall accidents, which have recently been an important issue of health problems in Korea, The data are from the Annual Report on the Cause of Death Statistics in Korea in 2008. They include the deaths over the age 19 from transportation accidents, suicides and fall accidents with the criterion of the International Statistical Classification of Diseases. Poisson HGLM is applied to estimate the mortality rate under the assumption that the number of deaths follow a Poisson distribution, by considering regions as random effects and by adjusting age, sex and standardized residence tax as fixed effects. Using the results of random effects prediction, the regional differences in cities, counties and towns are marked in disease mapping. The results showed that there were significant regional differences of mortality rates for transportation accidents and suicides, but no significant differences for fall accidents.

• Journal of Families and Better Life
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• v.31 no.3
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• pp.63-79
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• 2013

The aim of this study was to investigate the influence of family-friendly community policy and child care policy on parents with young children. Particularly, two specific questions were addressed: 1) Were there differences in the perception of community family-friendliness among parents with young children in Seoul provinces? 2) Were there differences in the perception of community family-friendliness among parents with young children, depending on child-care infrastructures in Seoul provinces? Data for this study were drawn from multiple sources. Individual-level indicators were drawn from the survey of 1,246 parents with children under age 6 in Seoul. Community-level indicators were drawn from the 2011 Seoul census data. Frequency, descriptive statistics, GIS mapping, and hierarchical linear model analysis were conducted to examine the perception of community family-friendliness by individual, child-care infrastructures, and the community at large. The major results of the present study are as follows: The perception of parents on community family-friendliness varied across the 25 provinces in Seoul. The perception of community family-friendliness was positively related with the total number of child day-care centers, and the number of infant-toddler child daycare centers. The number of accredited child daycare centers was negatively associated with the perception of community family-friendliness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3240-3250
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• 2014

This study aims to draw a correlation in the choice of automobiles as the preferred mode of personal transport in relation to three factors: 5Ds, urban form and individual-level characteristics. The analysis result shows that the control at the individual level is required to analyze effective urban character and urban form elements to decrease the car choice and the 5Ds demonstrate meaningful relation to decreasing the car choice. However, it may be concluded that the density and the diversity, well-known elements in decreasing the car choice among Western cities do not show relatively large impact on Korean cities.

• Journal of the Korean Society of Child Welfare
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• no.55
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• pp.143-171
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• 2016

This study investigated the effects of individual characteristics, school factors, and community factors on adolescent school violence behaviors. Data from a total of 1,777 middle school students from 50 schools in the Seoul and Gyeonggi regions were used for analysis. A hierarchical generalized linear modeling was employed to conduct a two-level analysis. Results showed that adolescents' individual factors, including attitudes toward violence, parental attachment, child abuse experiences, and affiliation with delinquent peers, as well as school factors including teacher's abusive classroom discipline, affected adolescent school violence behaviors. In addition, neighborhood disorder was found to be significantly positively correlated with adolescents' school violence. The results of this study suggest that for an understanding of school violence and to prepare countermeasures accordingly, integrated consideration of various environmental contexts in adolescents' daily lives, such as family, school, and community environments, is necessary. A multidimensional, integrated intervention plan to effectively resolve school violence based on these research results is discussed.