• Journal of Cadastre & Land InformatiX
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• v.48 no.2
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• pp.197-211
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• 2018

We conducted this research to examine how well regional housing prices are suited to use as an alternative to conventional census-based regional deprivation indices in health and medical geography studies. To examine the relative performance of mean regional housing prices compared to conventional census-based regional deprivation indices, we compared several multilevel logistic regression models, where the first level was individuals and the second was health districts in the Seoul Metropolitan Area (SMA) in Korea, for the sake of adjusting the regional clustering tendency of unknown factors. In these models, we predicted two dichotomous variables that represented individuals' after-lunch tooth brushing behavior and use of dental floss by individual characteristics and regional indices. Then, we compared the relative predictive performance of the models using the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC). The results from the estimations showed that mean regional housing prices and census-based deprivation indices were correlated with the two types of dental health behavior in a statistical sense. The results also revealed that the model with mean regional housing prices showed smaller AIC and BIC compared with other models with conventional census-based deprivation indices. These results imply that it is possible for housing prices summarized using aerial units to be used as an alternative to conventional census-based deprivation indices when the census variables employed cannot properly reflect the characteristics of the aerial units.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.2
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• pp.103-129
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• 1998

Corporate level decision making with multiple decision makers in a consistent way is essential in Decision Support System. However, since the decision makers have different interests and knowledge, the models used by them are also different in their level of abstraction. This makes decision makers waste a lot of efforts for an integrated decision making. The purpose of this paper is to propose an integration mechanism so that collaborative decision making models may be used synthetically in multi-abstraction level. Models are classified as multimedia model, mathematical model, qualitative model, causal ＆ directional model, causal model, directional model and relationship model according to the level of abstraction. The proposed integration mechanism consists of model interpretation phase. model transformation phase, and model integration phase. Specifically, the model transformation Phase is divided into (1) model tightening mode which gather information to make a model transformed into upper level model, and (2) model relaxing mode which makes lower level model. In the model integration phase, models of same level are to be integrated schematically. An illustrative M＆A-decision example is given to show the possibility of the methodology.

• Journal of The Korean Astronomical Society
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• v.23 no.1
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• pp.71-82
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• 1990

Theoretical calculations of the combined radiative transfer and statistical equilibrium equation including the charge-particle conservations have been earned out for a multilevel hydrogen atom in quiescent prominences. Cool and dense models show the steep changes of population and radiation field in the vicinity of the surface, while these physical quantities remain unchanged for models with temperature of 7,300K, regardless of total densities. Ionization rate of hydrogen atom related with metallic line formation varies in considerable amounts from the surface to the center of model prominences cooler than 6,300K. However, such cool models cannot release enough hydrogen line emissions to explain observed intensities. Prominence models with a temperature higher than 8,000K can yield the centrally reversed Lyman line profiles confirmed by satellite EUV observations. We find that queiscent prominence with a density between $2{\times}10^{11}$ and $10^{12}cm^{-3}$ should be in temperature range between 6,300K and 8,300K, in order to explain consistently observed H alpha, beta line emissions and $n_p/n_l$ ratio.

• The Journal of Korean Association of Computer Education
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• v.20 no.6
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• pp.83-94
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• 2017

The purpose of this study is to analyze factors affecting elementary school students' computational thinking and SW education attitude using a 3-level multi-level models. The results of this study are as follows: First, 'Computer at home', 'SW competition participation experience', 'SW education satisfaction', and 'SW awareness' have a statistically significant effect on the initial value of computational thinking while 'SW period of education' and 'SW education experience at after school' have a statistically effect on the change rate of computational thinking. Second, 'SW awareness', 'SW education satisfaction' and 'gender' have a positive effect on the initial values of SW education attitude whereas 'SW period of education' has a slight negative influence on the change rate of SW education attitude.

• Korea Real Estate Review
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• v.27 no.3
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• pp.51-70
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• 2017

This study aimed to measure street centralities with the street width, and to analyze their effects on the residential and non-residential land prices in Seoul, South Korea. Most of the studies on urban economics and policy focusing on the urban spatial structure have evolved in terms of their perspective from monocentric to polycentric models. Recently, their themes shifted to measuring street centralities and capturing their effects on urban phenomena. To expand the existing studies and discussion, this study analyzed the street centralities with the street width, and how they changed the land prices. Multilevel regression models generated a few key findings relevant to the relationship between street centralities and land prices. While a higher detour volume and closeness to wider streets commanded premium residential land prices, higher visibility and detour volume to wider streets were associated with higher non-residential land prices. These findings suggest a robust connection between street configuration and near-land prices. Thus, the results of this study suggest a few insightful policy implications for urban planners, urban designers, real estate developers, and appraisers.

• Journal of Preventive Medicine and Public Health
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• v.53 no.3
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• pp.189-197
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• 2020

Objectives: Our aim was to answer the following questions: (1) Can mental health variance be partitioned to individual and higher levels (e.g., neighborhood and district); (2) How much (as a percentage) do individual-level determinants explain the variability of mental health at the individual-level; and (3) How much do determinants at the neighborhood- or district-level explain the variability of mental health at the neighborhood- or district-level? Methods: We used raw data from the second round of the Urban Health Equity Assessment and Response Tool in Tehran (in 2012-2013, n=34 700 samples nested in 368 neighborhoods nested in 22 districts) and the results of the official report of Tehran's Center of Studies and Planning (in 2012-2013, n=22 districts). Multilevel linear regression models were used to answer the study questions. Results: Approximately 40% of Tehran residents provided responses suggestive of having mental health disorders (30-52%). According to estimates of residual variance, 7% of mental health variance was determined to be at the neighborhood-level and 93% at the individual-level. Approximately 21% of mental health variance at the individual-level and 49% of the remaining mental health variance at the neighborhood-level were determined by determinants at the individual-level and neighborhood-level, respectively. Conclusions: If we want to make the most effective decisions about the determinants of mental health, in addition to considering the therapeutic perspective, we should have a systemic or contextual view of the determinants of mental health.

• Journal of Korean Society of Transportation
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• v.21 no.4
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• pp.145-154
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• 2003

Multilevel and Multivariate Structural Equation Mpdel is applied to handle the hierarchical nature of the data and explain complex relationship among socioeconomic factors of individuals and household, activity participation, and travel behavior using Puset Sound Transportation Panel data. From analysis, variations of individual activity participation and travel behavior can be divided into two categories : Within-household variation and Between-households variation. Empirical results show that the interdependency index(p) of variables for household members within a household is between 0.13 and 0.33 indicating high interdependency. These results suggest that Multilevel and Multivariate SEM approach is an appropriate modeling methodology and gives additional information for activity participation and travel behavior. Also most of personal and household characteristics influence on activity participation and travel behavior within a household as well as between households.

• Human Ecology Research
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• v.61 no.3
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• pp.319-333
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• 2023

The purpose of this study was to examine which sibling and parent-child characteristics were associated with siblisng warmth and conflict among Korean young adults. The data came from an online survey of Koreans aged 19-34 years who had at least one sibling and two living parents. We conducted a multilevel regression analysis using data from 193 men with 305 siblings and 203 women with 286 siblings. The results showed that, for men, the levels of warmth were higher when the sibling was younger, when they received more frequent financial and instrumental support from the sibling, and when maternal favoritism was relatively lower. Women reported higher levels of warmth when the sibling was a sister, when they provided more frequent support for the sibling, when they had a more affectionate relationship with the mother, and when paternal favoritism was lower. As for sibling conflict, the number of siblings was positively associated with the levels of conflict among both men and women. Maternal affection was negatively related with conflict for men, and paternal favoritism was positively related to conflict for women. Interestingly, women's sibling warmth and conflict were both higher when the sibling was a sister, which meant that relationships between sisters tended to be ambivalent. This study contributes to our understandings of Koreans' sibling relationships in young adulthood.

• Journal of Power Electronics
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• v.16 no.1
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• pp.319-328
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• 2016

In this study, we first briefly introduce the effect of circulating current control on the modulation signal of a modular multilevel converter (MMC). The maximum modulation index is also theoretically derived. According to the optimal modulation index analysis and the model in the continuous domain, different DC-side output impedance equivalent models of MMC with/without compensating component are derived. The DC-side impedance of MMC inverter station can be regarded as a series xR + yL + zC branch in both cases. The compensating component of the maximum modulation index is also related to the DC equivalent impedance with circulating current control. The frequency characteristic of impedance for MMC, which is observed from its DC side, is analyzed. Finally, this study investigates the prediction of the DC voltage ripple transfer between two-terminal MMC high-voltage direct current systems under unbalanced conditions. The rationality and accuracy of the impedance model are verified through MATLAB/Simulink simulations and experimental results.

• Journal of the Korean Data and Information Science Society
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• v.24 no.4
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• pp.931-940
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• 2013

For analysis of clustered survival data, the inferences of parameters in semi-parametric frailty models have been widely studied. It is also important to investigate the potential heterogeneity in event times among clusters (e.g. centers, patients). For purpose of this analysis, the interval estimation of frailty is useful. In this paper we propose a visualizing method to present confidence intervals of individual frailties across clusters using the frailtyHL R-package, which is implemented from h-likelihood methods for frailty models. The proposed method is demonstrated using two practical examples.