• Structural Engineering and Mechanics
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• v.69 no.2
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• pp.193-204
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• 2019

This paper presents results from experimental and numerical studies on the response of steel-concrete composite box bridge girders under certain localized fire exposure conditions. Two composite box bridge girders, a simply supported girder and a continuous girder respectively, were tested under simultaneous loading and fire exposure. The simply supported girder was exposed to fire over 40% of its span length in the middle zone, and the two-span continuous girder was exposed to fire over 38% of its length of the first span and full length of the second span. A measurement method based on comparative rate of deflection was provided to predict the failure time in the hogging moment zone of continuous composite box bridge girders under certain localized fire exposure condition. Parameters including transverse and longitudinal stiffeners and fire scenarios were introduced to investigate fire resistance of the composite box bridge girders. Test results show that failure of the simply supported girder is governed by the deflection limit state, whereas failure of the continuous girder occurs through bending buckling of the web and bottom slab in the hogging moment zone. Deflection based criterion may not be reliable in evaluating failure of continuous composite box bridge girder under certain fire exposure condition. The fire resistance (failure time) of the continuous girder is higher than that of the simply supported girder. Data from fire tests is successfully utilized to validate a finite element based numerical model for further investigating the response of composite box bridge girders exposed to localized fire. Results from numerical analysis show that fire resistance of composite box bridge girders can be highly influenced by the spacing of longitudinal stiffeners and fire severity. The continuous composite box bridge girder with closer longitudinal stiffeners has better fire resistance than the simply composite box bridge girder. It is concluded that the fire resistance of continuous composite box bridge girders can be significantly enhanced by preventing the hogging moment zone from exposure to fire. Longitudinal stiffeners with closer spacing can enhance fire resistance of composite box bridge girders. The increase of transverse stiffeners has no significant effect on fire resistance of composite box bridge girders.

• Women's Health Nursing
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• v.28 no.2
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• pp.123-133
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• 2022

Purpose: This study investigated the trajectory of subjective health status in married postmenopausal women and aimed to identify predictive factors affecting subjective health status. Methods: Data were obtained from women who participated in wave 4 (2012) of the Korean Longitudinal Survey of Women & Families Longitudinal Study and continued to the latest phase (wave 7, 2018). A latent growth model (LGM) was used to analyze data from 1,719 married postmenopausal women in the framework of the ecological system theory. Results: The mean age of the participants at wave 4 was 56.39±4.71 years, and the average subjective health status was around the midpoint (3.19±0.84). LGM analysis confirmed that subjective health status decreased over time (initial B=3.21, slope B=-0.03). The factors affecting initial subjective health were age, body mass index, frequency of vigorous physical activity (microsystem level), marital satisfaction (mesosystem level), and medical service utilization (macrosystem level). Medical service utilization and the frequency of vigorous physical activity were identified as predictive factors affecting the slope in subjective health status. The model fit was satisfactory (TLI=.92, CFI=.95, and RMSEA=.04). Conclusion: This analysis of the trajectory of subjective health status of married postmenopausal women over time confirmed that subjective health is influenced by overall ecological system factors, including the microsystem, mesosystem, exosystem, macrosystem, and chronosystem. Therefore, it is necessary to assess physical activity and support policies promoting access to medical services in order to improve the subjective health status of married postmenopausal women.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.311-318
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• 2006

This paper presents experimental studies on investigating the seismic retrofit performance of reinforced concrete circular columns with poor lap-splice details using GFRP wrapping. Five full-scale model columns have been tested. The prototype structure is an existing circular reinforced concrete bridge piers designed following the pre-seismic codes and constructed in South Korea in 1979. The as-built column will be expected to suffer brittle failure due to the bond failure of lap-spliced longitudinal reinforcement. The retrofitted columns using GFRP wrapping showed significant improvement of seismic performance. However, the predicted flexural failure mode was not achieved and the longitudinal bars were not yielded. Failure modes of the retrofitted columns are considered to be the gradually delayed bond slip in lap-spliced longitudinal reinforcement. Suggested retrofit design methods using GFRP were validated experimentally.

• The Journal of the Korea Contents Association
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• v.19 no.7
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• pp.138-148
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• 2019

Although social relation factors are confirmed to be closely associated with the depression level of the elderly through the preceding studies, there has been no specific study on subfactors of social relation that influence the trajectory of depression level. Considering such limitation, this study aims to analyze influencing subfactors of social relation on the trajectory of depression of the elderly. The 3rd, 4th, 5th, and 6th-year data of the Korean Longitudinal Survey of Ageing (KLoSA), which were provided by the Korea Employment Information Service (KEIS), were used in this study and 2,484 people aged 65 and over who responded to all the four-session surveys were used as final analysis subjects. In the result of the longitudinal study on depression level of the elderly aged 65 and over, the individual depression level was confirmed become lowered over time, showing a positive change. Also, the conditional model of Latent Growth Modeling (LGM) was applied to identify specific social network factors that influence the longitudinal change of depression level of the elderly. In the result of the analysis, it was found that initial value of depression of the elderly was influenced by whether they have a spouse or not, number of household member, meeting with close people, whether they do economic activity or not, whether they have a religion or not, etc. and the rate of change in depression of the elderly was influenced by number of household member, meeting with close people, expectation about life, etc. Through above results, this study suggests a need for specific programs and supports to continuously lower the depression level of the elderly.

• Korean Journal of Child Studies
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• v.30 no.6
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• pp.323-336
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• 2009

There has been a significant increase in the number of divorced families during the past 10 years in Korea. Divorce imposes a great impact on their children as well as divorcees. As many as 1.41 million children under 20 years-old have experienced their parents' divorce in past 10 years. Children are faced with much difficulty in adjustment after the parental divorce. Issues of the research and policy on the divorced family are discussed in this study. For future studies, a longitudinal research model, father-custody and grandparent-custody families, custody parents's gender, a theoretical model for Korean divorced families should be considered. New legislations have been recently enacted to enhance children's well-being, but further efforts such as the involvement of child development specialists in the divorce process should be followed in the pursuit of the best interest of the children.

• Korean Journal of Child Studies
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• v.30 no.6
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• pp.15-28
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• 2009

Parenting or parenting behaviors has been a key subject during the last three decades. Studies on the parenting mainly focused on either the associations between mothers' parenting and child outcomes or variables predicting parenting behaviors. Regarding child outcomes, social-emotional development of children has been more frequently studied than their cognitive development. Also, the characteristics of parents, children, and contextual environments have received attention in predicting mothers' parenting behaviors. Recently, there have been attempts in identifying the processes that are hypothesized to mediate or moderate the relationships between parenting and developmental outcomes. Furthermore, the studies using longitudinal data have been increased as well. For a future direction, the age-specific and culturally sensitive measures assessing Korean mothers' parenting behaviors are needed. Research efforts and policies should be directed toward supporting parents and their children from diverse backgrounds in the rapidly changing Korean society.

• Korean Journal of Child Studies
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• v.33 no.4
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• pp.1-17
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• 2012

This study examined the developmental trajectories of perceived level of stress and depression in Korean youth using longitudinal data from the Korean Youth Panel Study (KYPS) of 2,844youth (1,524 boys) across $4^{th}$ grade through $8^{th}$ grade. Latent growth modeling indicated the presence of age-related, significant increases in stress and depression for both boys and girls. Girls experienced greater in stress and depression than did boys. Multiple group analysis indicated that there was no significant sex difference in effects of stress on depression. Overall, increases in stress were associated with increases in depression levels for both boys and girls. Conceptual and clinical implications of the findings were discussed.

• Sleep Medicine and Psychophysiology
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• v.9 no.2
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• pp.100-105
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• 2002

Personality traits in insomniac patients have been a subject of many studies. A number of these studies have used the MMPI and have demonstrated elevated scores on several clinical scales reflecting somatic concerns, somatization, depression, anxiety, worry and social alienation. And it was suggested that insomnia was due to a process of internalization of psychological distress. Another hypothesis about psychological mechanisms has focused upon worry. Excessive and uncontrollable cognitive activity seem to be a characteristic feature of many insomniacs. One author emphasized the role of the dependency need and found a characteristic pattern among insomniacs. The central feature of this pattern is frustration of dependency need. The purpose of this paper was to review possible personality variable that may be predisposing causal factors of insomnia. Several factors are suggested by many studies, but in order to explore their causal importance other experimental and longitudinal studies are needed.

• Korean Journal of Child Education & Care
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• v.18 no.1
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• pp.77-102
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• 2018

The objectives of this study were to analyze the longitudinal mediation effects of maternal parenting stress and psychosocial development of infant on the influence of paternal involvement during infancy to children's peer interactions. For these objectives, latent growth modeling was used and adapted to the data taken from the Panel Study on Korean Children(PSKC), Wave I (0-year olds) to Wave III (2-year olds) and Wave V(4-year olds) to Wave VII(6-year olds). During a total of six years, 1,018 parent responded. The major results of this study were as follows. First, maternal parenting stress(initial status) had a significant mediating effect on the influence of paternal involvement(initial status) to children's play interaction(initial status). Second, maternal parenting stress(initial status/change rate) had a longitudinal mediating eff ect on the influence of paternal involvements(initial status/change rate) to children's play disruption-disconnection interactions(initial status/change rate). Third, psychosocial development of infants(initial status/change rate) had a longitudinal mediating effect on the influence of paternal involvement(initial status/change rate) to children's play interactions(initial status/change rate). Fourth, psychosocial development of infant(initial status) had a significant mediating effect on the influence of paternal involvement(initial status) to children's play disruption-disconnection interactions(initial status). The implications of the findings of the current study and suggestions for future research were also discussed.

• Korean Journal of Social Welfare Studies
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• v.42 no.3
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• pp.183-206
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• 2011

This study examined the longitudinal relationship between academic achievement and school satisfaction using a data of the Seoul Panel Study of Children(SPSC). Fully autoregressive cross-lagged analysis and multi-group comparison were performed to measure the longitudinal relationship between two constructs as well as differences between poverty and non-poverty groups. The results showed that both academic achievement and school satisfaction were stable over time in non-poverty group. Academic achievement at the 4th grade significantly affected the school satisfaction at the 6th grade and it subsequently affected on the academic achievement at the 8th grade in non-poverty group. In contrast, academic achievement was not consistent over time in poverty group. Only the school satisfaction at the 6th grade affected the academic achievement at the 8th grade. The findings of this study have various practical implication for school interventions. It is more important to keep supporting the children to maintain the level of academic achievement in non-poverty group. While, in poverty group, it is essential to make school satisfaction and academic motivation increase with school attachment programs.