• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.117-122
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• 2002

Flat Plate structures subjected to lateral load are susceptible to the brittle failure, therefore deformability of plate-column connections should be ensured to resist against earthquake. However, according to previous study, existing experiments overestimate the deformability of connections and current design provision do not accurately explains them. In the present study, parametric study using nonlinear finite element analysis was performed. Based on the numerical results, seismic design method considering the deformability of connections was developed.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.361-365
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• 2007

풍력 발전기의 블레이드 설계를 위하여 각 설계 변수에 대한 영향을 파악하기 위하여 연구를 수행하였다. 블레이드의 공력 형상을 결정짓는 설계 변수를 분류하고 이에 대하여 parametric study를 통하여 각 설계 변수가 주어진 환경에서 블레이드의 성능 및 하중에 어떠한 영향을 주는 가에 대하여 살펴보았다. 이를 블레이드의 성능 및 기준 하중에 대한 해석은 BEMT를 이용하였다. 본 결과는 블레이드의 실제 공력 설계에서 설계 변수의 선정과 그 영향에 대하여 미리 파악하는데 도움을 줄 것으로 기대된다.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.187-192
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• 2003

Nowadays, It has adapted both Ultimate Strength Design(USD) and Allowable Stress Design(ASD) Method evaluating load-carrying capacity of PSC I Type Girder Bridge. But it has confused because the each method has brought some different results. This study shows some results of loading test of the PSC I type Girder Bridge and analyzed the structural behavior by FEM analysis considering material nonlinear. Parametric study of effective prestress of post tendon is performed and compared to results of loading test.

• 연구논문집
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• s.22
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• pp.141-150
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• 1992

A basic study on the batch type freeze dryer has been carried out. The operating principles, merits and demerits of the freeze dryer were described. And the kinds of major components and their roles were also invesigated. As a fundamental study, using the Differential Scanning Calorimeter(DSC), the determination of unfrozen water in the specimens and invesigation of effects of cooling rate on the freeze drying were performed. To provide a guidline of basic design for a freeze dryer, a parametric study about the drying conditions was carried out.

• Journal of the Korean Geotechnical Society
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• v.26 no.2
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• pp.45-54
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• 2010

The SCW numerical model described in the companion paper was used to carry out a comprehensive parametric study to evaluate the performance of the SCW. The five ground related parameters, which are porosity, hydraulic conductivity, thermal conductivity, specific heat, geothermal gradient, and five SCW design parameters, which are pumping rate, well depth, well diameter, dip tube diameter, bleeding rate, were used in the study. Two types of numerical simulations were performed. The first type was used to perform short-term (24-hour) simulation, while the second type 14 day simulation. The study results indicate that the parameters that have important influence on the performance of SCW were hydraulic conductivity, thermal conductivity, geothermal gradient, pumping rate, and bleeding rate. The thermal conductivity had the most important influence on the performance of the SCW. With the increase in the geothermal gradient, the performance increased in the heat mode, but decreased in the cooling mode. The hydraulic conductivity influenced the performance when the value was larger than $10^{-4}m/s$. The depth of the well increased the performance, but at the cost of increased cost of boring. The bleeding had an important influence on SCW, greatly enhancing the performance at a limited increased cost of operation. Overall, this study showed that various factors had a cumulative influence on the performance of the SCW, and a numerical simulation can be used to accurately predict the performance of the SCW.

• Survey Research
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• v.10 no.3
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• pp.37-58
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• 2009

The purpose of this study were to identify the subgroups (i.e., latent classes) depending on early adolescents' change patterns in aggression and to test the effects of individual-background variables on determining the latent classes. For these goals, we applied Nagin's(1999) semi-parametric group-based approach to the Korean Youth Panel Study. Results showed that four latent classes were identified, which could be defined based on the patterns as low-level group, increasing group, intermediate-level group, and high-level group. By adding gender, self-control, parent attachment, teacher attachment, and the number of delinquent friends to the unconditional latent class model, we tested the effects of the variables on the latent classes. Multinomial logit analysis showed that gender, self-control, teacher attachment, and the number of delinquent friends were significant determinants of the latent classes. Findings from this study suggest the need to consider heterogeneity in the study of early adolescents' aggression to facilitate more refined targeting of intervention program.

• Journal of the Korean GEO-environmental Society
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• v.5 no.1
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• pp.55-64
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• 2004

Stone column is a soil improvement method and can be applicable for loose sand or weak cohesive soil. Since the lack of sand in korea, stone column seems one of the most adaptable approach for poor ground as a soil improvement technique. However, this method was not studied for practical application. In this paper, the most affective design parameters for the bearing capacity of stone column were studied. The parametric study of major design factors for single stone column was carried out under the bulging and general shear failure condition, respectively. Especially, a test result of single stone column by static load was compared with the bearing capacity values of suggested formulas. The analysis result showed that the ultimate bearing capacity by the formula was much less than the measured value by the static load test. Especially, the result of the parametric study under general shear failure condition showed that the bearing capacity has big difference between each suggested formulas with the variation of the major design parameters. Therefore, the result of this study can be appliable for the future stone column project.

• 한국노년학
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• v.32 no.4
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• pp.1063-1086
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• 2012

The purpose of this study is to understand the current state of the older people's social exclusion by identifying patterns of the change in social exclusion level through a longitudinal analysis with an aim of exploring the predictors of changes. To this end, this study has adopted the panel data, the English longitudinal Study of Ageing(ELSA). The data of 7631 respondents who aged over 50 were used for the final analysis. The social exclusion of the older people was analyzed into five different sub-dimensions: social relationship; cultural activities; access to health services; financial security; and sense of loneliness. The person-centered approach that focuses on the various patterns of the trajectories of change has used semi-parametric group based model in order to estimate different trajectories among individuals. The data was analyzed using Spss 18.0 and SAS 9.2 proc traj. In results, First, semi-parametric group-based model analysis has shown that the older people are not 'homogeneous' group with similar exclusion level in every individual with same trajectories of change, but can be divided into various categories with diverse intercept and slope. Second, different trajectories in change of exclusion level help to confirm that the older people's social exclusion level increases gradually over time or remains unchanged. Third, this analysis has provided the useful guidelines to identify the high-risk groups of social exclusion. Forth, the variables that make difference in more than three dimensions include gender, age, self-perceived health, physical activity, weekly income, marital status, family relation, and beneficiary status. Implications and further suggestion were discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.281-288
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• 2008

The Prestressed Concrete (hereinafter PSC) box girder bridges with corrugated steel webs have been drawing an attention as a new structure type of PSC bridge fully utilizing the feature of concrete and steel. However, the previous study focused on the shear buckling of the corrugated steel web and development of connection between concrete flange and steel web. Therefore, it needs to perform a study on the torsional behavior and develop the rational torsional analysis model for PSC box girder with corrugated steel web. In this study, torsional analysis model is developed using Rausch's equation based on space truss model, equilibrium equation considering softening effect of reinforced concrete element and compatibility equation. Validation studies are performed on developed model through the comparison with the experimental results of loading test for PSC box girder with corrugated steel webs. Parametric studies are also performed to investigate the effect of prestressing force and concrete strength in torsional behavior of PSC box girder with corrugated steel web. The modified correction factor is also derived for the torsional coefficient of PSC box girder with corrugated steel web through the parametric study using the proposed anlaytical model.

• 한국노년학
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• v.37 no.3
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• pp.617-635
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• 2017

The aim of this study was to investigate both poverty and depression among older adults, focusing on the relationship of these two trajectories. For expanding the understanding about elderly poverty and depression, the study measured the longitudinal patterns of various transition in these two variables. The data for the study is 1st to 9th waves (2006-2014) of Korea Welfare Panel Study (KoWePS), and 4,431 older adults were used for the final analysis. For data analysis, Semi-parametric group-based modeling and Dual trajectory model were selected. The main results of this study were followings; First, The trajectory groups were identified: non-poverty, decrease poverty, increase poverty, remain high-poverty, chronic poverty groups and 4 trajectories of depression: stable, remain low-depression, risk of depression, chronic depression groups. Second, the study was tried to anticipate the longitudinal transition of poverty and depression status, and investigate the concurrent relationship in these two variables. It turned out that the stable poverty status led the stable depression, and vice versa. Based on these result, this study for elderly welfare were discussed to reduce risk for poverty and depression.