• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.114-122
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• 2002

The ASCE formula of lifeline.soil interaction force is the basis of semi-analytical relationship for buried pipelines subjected to longitudinal permanent ground deformation due to seismic induced liquefaction. However, since the ASCE formula has been developed based on the stiffness of non-liquefied region, it is needed to modify for the varied stiffness of liquefied region. With this object, the consideration of decreasing effect of soil stiffness in liquefied region is made: i.e. the spatial distributions of pipeline-soil interaction force in liquefied region. It means that the improved formula can reflect various patterns of permanent ground deformation more realistically. Through the comparative analyses using both the improved and ASCE formula, the applicability of the improved and the limitation of the ASCE formula and semi-analytical relationship are discussed. Also, relative influences of various parameters are evaluated for the clarification of behavior of pipeline subjected to longitudinal permanent ground deformation due to liquefaction.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.170-175
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• 2003

The ASCE formula of pipeline' soil interaction force is the basis of semi-analytical relationship for buried pipelines subjected to longitudinal permanent ground deformation due to seismic induced liquefaction. However, since the ASCE formula has been developed based on the stiffness of non-liquefied region, it is needed to modify for the varied stiffness of liquefied region. With this object, the consideration of decreasing effect of soil stiffness in liquefied region is made: i.e. the spatial distributions of pipeline. soil interaction force in liquefied region. It means that the improved formula can reflect various patterns of permanent ground deformation more realistically. Through the comparative analyses using both the improved and ASCE formula, the applicability of the improved, the limitation of the existing formula and semi-analytical relationship are discussed.

• 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.

• Fire Science and Engineering
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• v.22 no.3
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• pp.201-207
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• 2008

In this study, three Dimensional CFD simulations were carried out to investigate the effective smoke extraction system in bi-directional road tunnel fires using FLUENT. Characteristics of transverse system with big size extraction port or with uniform extraction port, semi-transverse system and longitudinal system for smoke extraction system were analyzed. Air velocity, port size, and operating method were used with variable. Distributions of smoke spread, CO was analyzed. As a result, the transverse ventilation system with big size port was found to be more effective than the uniform ports for bi-directional road tunnel.

• Journal of Periodontal and Implant Science
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• v.49 no.4
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• pp.206-214
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• 2019

Purpose: The purpose of this study was to examine the association between the intake of semi-solid yogurt and periodontitis in Korean adults using a national database. Methods: The data analyzed in this study are a subset of the sixth Korean National Health and Nutrition Examination Survey conducted in 2015 by the Korea Centers for Disease Control and Prevention. The sample size for this study was 4,727. We collected data on sociodemographic characteristics, oral health-related variables, oral and general health status, and intake of semi-solid yogurt. Semi-solid yogurt intake (YI) was calculated by multiplying the frequency of YI over the previous week by the average intake per serving. We assessed periodontal conditions using the Community Periodontal Index (CPI) and defined periodontitis as a CPI score ${\geq}3$. Multivariate logistic regression analyses were performed after adjusting for sociodemographic variables, and oral and general health behaviors and status. Results: The mean weekly YI among those without periodontitis ($1.03{\pm}0.06cups$) was significantly higher than among those with periodontitis ($0.77{\pm}0.08cups$) (P<0.001). Individuals who consumed more than 2 cups of yogurt per day were 76% less likely to have periodontitis than those who consumed less than 1 cup of yogurt per week after adjusting for all covariates (odds ratio, 0.24; 95% confidence interval, 0.10-0.60). Conclusions: We found a significant association between increased intake of semi-solid yogurt and periodontal health. We therefore recommend daily consumption of semi-solid yogurt as a probiotic to improve periodontal health. Further longitudinal studies are required to elucidate plausible mechanisms through which probiotics impact periodontal disease, considering both periodontal pathogens and clinical periodontal parameters.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.10a
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• pp.27-34
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• 1995

Elastic and in-elastic buckling stress analyses are executed by the semi-analytical finite strip method to study the effect of the longitudinal stiffener on the web of box girders. The simple analysis procedure is based on the assumption that the vertical stiffeners has the rigidity enough to force nil deflection line on the web panel so that the boundary condition may be regarded as a hinge. The provisions on the longitudinal stiffeners in plate girders of the Korean Standard Highway Bridge Specifications(1992) are investigated through comparison with the results obtained for various web stiffener size of box girders of the medium span length bridges.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.3
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• pp.187-197
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• 2015

This study aims the development of a semi-analytic method for the parametric roll of large containerships advancing in longitudinal waves. A 1.5 Degree-of-Freedom(DOF) model is proposed to account the change of transverse stability induced by wave elevations and vertical motions (heave and pitch). By approximating the nonlinearity of restoring moment at large heel angles, the magnitude of roll amplitude is predicted as well as susceptibility check for parametric roll occurrence. In order to increase the accuracy of the prediction, the relationship between righting arm(GZ) and metacentric height(GM) is examined in the presence of incident waves, and then a new formula is proposed. Based on the linear approximation of the mean and first harmonic component of GM, the equation of parametric roll in irregular wave excitations is introduced, and the computational results of the proposed model are validated by comparing those of weakly nonlinear simulation based on an impulse-response-function method combined with strip theory. The present semi-analytic doesn’ t require heavy computational effort, so that it is very efficient particularly when numerous sea conditions for the analysis of parametric roll should be considered.

• 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.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.10a
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• pp.287-300
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• 2008

Airflow distributions along tunnel and over the cross section are critical in selecting installation location of the velocity monitor to obtain the representative data for ventilation as well as fire safety systems. This paper aims at performing CFD and on-site studies to analyze the longitudinal and cross-sectional distributions of the air velocity in tunnels employing longitudinal and semi-transversal ventilation systems. This study can ultimately contribute to selecting the monitor type as well as the optimal installation locations in vehicle tunnel.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.1
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• pp.1-9
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• 2022

Semi-integral abutment bridges are a type of integral abutment bridges. These bridges eliminate expansion joints on the structure and can be used in situations not suitable for full-integral abutment bridge. Moreover, Semi-integral bridges have excellent maintenance and can be economically constructed. This study is about precast wall-type blocks at each end which provide lateral support for PSC girder, as well as acting as retaining walls to resist longitudinal movement of semi-integral abutment bridge. The end-diaphragm connection between ended blocks of PSC girders can be achieved by in-suit nonshrinkage concrete. The results show that 3-point experiment of end-diaphragm beam have an acceptable performance which is so better than results of structural design. Moreover, the effects of backfill soil on semi-integral abutment bridge constructed are analyzed the behavior according to the temperature changes.