• Structural Engineering and Mechanics
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• v.62 no.6
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• pp.725-737
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• 2017

An analytical method considering axial equilibrium is proposed for the short- and long-term analyses of shear lag effect in reinforced concrete (RC) box girders. The axial equilibrium of box girders is taken into account by using an additional generalized displacement, referred to as the longitudinal displacement of the web. Three independent shear lag functions are introduced to describe different shear lag intensities of the top, bottom, and cantilever plates. The time-dependent material properties of the concrete are simulated by the age-adjusted effective modulus method (AEMM), while the reinforcement is assumed to behave in a linear-elastic fashion. The differential equations are derived based on the longitudinal displacement of the web, the vertical displacement of the cross section, and the shear lag functions of the flanges. The time-dependent expressions of the generalized displacements are then deduced for box girders subjected to uniformly distributed loads. The accuracy of the proposed method is validated against the finite element results regarding the short- and long-term responses of a simply-supported RC box girder. Furthermore, creep analyses considering and neglecting shrinkage are performed to quantify the time effects on the long-term behavior of a continuous RC box girder. The results show that the proposed method can well evaluate both the short- and long-term behavior of box girders, and that concrete shrinkage has a considerable impact on the concrete stresses and internal forces, while concrete creep can remarkably affect the long-term deflections.

• Korean Journal of Childcare and Education
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• v.12 no.3
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• pp.1-19
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• 2016

The purpose of this study was to examine the effect of parenting efficacy measured at 6 months of infancy, and on parenting stress at 9-months of infancy through a short-term longitudinal approach. Participants were 116 couples living in Seoul and Gyeonggi-do, whose first born children were in infancy. The results of the 116 couples were analyzed through the APIM analysis method. The results of the APIM showed that mothers' and fathers' actor effect was significant, which meant that parenting efficacy at 6 months of infancy could predict the existence of parenting stress at 9 months of infancy. However, the partner effect of both mothers and fathers was insignificant. This research demonstrates the significance of parenting efficacy at early infancy, which in turn affects parenting stress as well as factors that need to be considered in pre-parental education.

• Journal of the Korea Convergence Society
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• v.11 no.5
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• pp.281-288
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• 2020

This study examined an effect of mother's smart device overdependence and short-term longitudinal mediation effect of mother's responsiveness on children's overindulgence tendency in smart devices. A total 144 children-mother dyads(male 73, female 71) participated in the study. The results of path analysis were as follows. The mother's smart phone overdependence and children's overindulgence tendency in smart devices were measured at time 1 and mother's responsiveness and children's overindulgence tendency were measured at time 2, six months later. When Time 1 children's overindulgence tendency in smart devices was controlled, Time 1 mother's smart phone overdependence significantly predicted time 2 children's overindulgence tendency. This study suggested empirical findings that caregiver's smart device were related with children's overindulgence tendency.

• Korean Journal of Childcare and Education
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• v.11 no.1
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• pp.289-303
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• 2015

The aim of this study was to examine the short-term longitudinal effect of creativity-fostering programs for pre-early childhood teachers on their problem solving ability and self-efficacy. The participants of this study were 67 pre-early childhood teachers (36 from the experimental group and 31 from the control group) in Seoul, Kyunggi-do, and Chungcheong-do, Korea. Pre-early childhood teachers' problem solving ability and self-efficacy was measured three times. Data were analyzed with a $2{\times}3$ ($group{\times}test$) two-way analysis of variance for repeated measures. The change in problem solving and self-efficacy appeared to be dependent on the group and test. Further statistical analysis of the data indicated that the participation of creativity-fostering programs for pre-early childhood teachers was longitudinally effective on their problem solving ability and self-efficacy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3007-3015
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• 2012

This study gave an insight into senior life plans and life satisfaction of the middle aged employee over 45 and under 60 years of age, listed in the KLIPS data for 2001 (4th year) and 2008 (11th year), so as to grasp levels of senior life plans of the middle aged employee as well as the longitudinal and short term effects of senior life plans on life satisfaction. The study findings showed as follow: First, For the period of years, the middle aged employees' health got worse and jobs got instable. Second, economic and physical senior life plans of the middle aged employee turned out below an average of three points which means preparations made below the normal level, whereas senior life plans in terms of relation and leisure and social activities came out with more than an average of three points, respectively, which means preparations made above the normal level. Third, as a result of looking into longitudinal effects of the 2001 senior life plans on life satisfaction, the level of senior life plans for leisure and social activities got higher, life satisfaction stayed higher in the year of 2001. In 2008, however, the higher level of economic plans for senior life came out with a higher rate of life satisfaction. From a short-term perspective, therefore, leisure and social activities to enjoy life impose a great impact on life satisfaction, whereas from a long-term viewpoint economic plans for senior life is regarded to be of greater importance.

• Smart Structures and Systems
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• v.32 no.2
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• pp.83-99
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• 2023

The temperature prediction approaches of three important locations in an operational longitudinal slab track-bridge structure by using three typical neural network methods based on the field measuring platform of four meteorological factors and internal temperature. The measurement experiment of four meteorological factors (e.g., ambient temperature, solar radiation, wind speed, and humidity) temperature in the three locations of the longitudinal slab and base plate of three important locations (e.g., mid-span, beam end, and Wide-Narrow Joint) were conducted, and then their characteristics were analyzed, respectively. Furthermore, temperature prediction effects of three locations under five various meteorological conditions are tested by using three neural network methods, respectively, including the Artificial Neural Network (ANN), the Long Short-Term Memory (LSTM), and the Convolutional Neural Network (CNN). More importantly, the predicted effects of solar radiation in four meteorological factors could be identified with three indicators (e.g., Root Means Square Error, Mean Absolute Error, Correlation Coefficient of R2). In addition, the LSTM method shows the best performance, while the CNN method has the best prediction effect by only considering a single meteorological factor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2537-2547
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• 2015

The aim of this study was to examine the longitudinal effect of Pre-service Teacher Education Program for Children's Creativity. The participants of this study were 67 pre-service teachers in Seoul, Kyungggi-do, and Chungcheong-do, Korea. Thirty-six pre-service teachers were assigned to the control group and pre-service teachers were assigned to the experimental group. Pre-service teacher's creativity was measured in three times. TTCT was applied to measure pre-service teacher's creativity and their children's creativity. Multivariate Latent Growth Model was applied to verify the effect of the program on pre-service teacher's creativity. Also, Multiple Regression was used to examine the effect of the program on their children's creativity. As a result, the participation of the program was longitudinally effective on not only pre-service teacher's creativity development but also their children's creativity. The results of current study suggested that it is necessary to help the pre-service teachers foster their creativity in early childhood teacher preparation program.

• Journal of Korean Academy of Nursing
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• v.26 no.3
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• pp.709-729
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• 1996

This study was done to analyze the trends of research on coping in Korea, to suggest future direction, for research on coping, and ultimately to contribute to an increase in explanation of adaptation. This article reviewed 79 nursing research papers on coping done since 1978 by examining them according to the period of publication or presentation, research design, type of subjects, measurement instruments, research for a degree or not, range of reliability, and association of coping and related variables. The results are as follows : The number of studies on coping increased rapidly from the mid-1980's and decreased slowly from the mid-1990's. The maority of the studies were surveys, comparative studies, or correlational studies. The subects of the 46 studies were healthy people, while those in the remaining studies were patients with a variety of illnesses. Thirth-eight studies on coping were done for master's thesis, three for dissertion, and 38 were not degrees. The Bell and Jalowiec coping scales have not been used since the early 1990's. In contrast, Lazarus and Folkman's W.C.C.L. has been used increasingly since that time. The reliabilities of the coping scale were reported in 37 cases and the Cronbach's alpha coefficients were .71 to .86. All subjects reported using more problem-oriented coping than emotion-oriented coping in short-term or emotion-oriented coping and healthy groups did more long-term coping. It was difficult to describe consistently the relationship between stress and coping according to the type of coping scale or research subjects, but generally moderate relationships were found. This was due to instrumental problems and no consideration of situational context. The subject group who used more short-term coping and less long-term coping reported poorer mental status, and higher scores in burnout and state anxiey than others. That is, the relationship between stress and adaptation increased the power of explanation with intervening the mediating effect of coping. The association of locus of control, mastery, social support, and self-concept with coping showed positive relationships : those of uncertainty and severity in illness with coping showed negativerelationships ; those of state anxiety and depression with short-term coping were positive, and those of self-esteem with long-term coping or problem-oriented coping were negative. There were significant differences in the scores of types of coping according to religion, level of education, and socio-economic status. That is, Presbyterians and Catholics, those with higher education levels and higher socio-economic status used more long-term or problem-oriented coping. On the basis of the above findings the following recommendations are made : 1. There is a need to test the mediating effect of coping variable in order to clarify the concept. 2. Longitudinal studies are needed to determine the patterns of change in coping strategies when stressful events are encountered. 3. It's necessary to develop a reliable and variable measurement tool for coping. 4. There is a need to identify subscales of coping to increase explanation of variance 5. It's necessary to consider personal, situational, and antecedent variables : the characteristics of subject populations, the natures of illness and treatment situations. 6. The power of explanation of studies designed to identify the stress-adaptation process should be increased using the combination model of process-oriented coping and cognitive-structural model.

• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.37.1-37.15
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• 2022

Background: This study investigated the effect of dispatch frequency on blood cadmium levels and the effect of blood cadmium levels on hypertension in male firefighters in a metropolitan city. Methods: We conducted a retrospective longitudinal study of male firefighters who completed the regular health checkups, including a health examination survey and blood cadmium measurements. We followed them for 3 years. To investigate the effect of dispatch frequency on blood cadmium levels and the effect of blood cadmium levels on hypertension, we estimated the short-term (model 1) and long-term (model 2) effects of exposure and hypothesized a reversed causal pathway model (model 3) for sensitivity analysis. Sequential conditional mean models were fitted using generalized estimating equations, and the odds ratios (ORs) and the respective 95% confidence intervals (CIs) were calculated for hypertension for log-transformed (base 2) blood cadmium levels and quartiles. Results: Using the lowest category of dispatch frequency as a reference, we observed that the highest category showed an increase in blood cadmium levels of 1.879 (95% CI: 0.673, 3.086) ㎍/dL and 0.708 (95% CI: 0.023, 1.394) ㎍/dL in models 2 and 3, respectively. In addition, we observed that doubling the blood cadmium level significantly increased the odds of hypertension in model 1 (OR: 1.772; 95% CI: 1.046, 3.003) and model 3 (OR: 4.288; 95% CI: 1.110, 16.554). Using the lowest quartile of blood cadmium levels as a reference, the highest quartile showed increased odds of hypertension in model 1 (OR: 2.968; 95% CI: 1.121, 7.861) and model 3 (OR: 33.468; 95% CI: 1.881, 595.500). Conclusions: We found that dispatch frequency may affect blood cadmium levels in male firefighters, and high blood cadmium levels may influence hypertension in a dose-response manner.

• Korean Journal of School Psychology
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• v.18 no.2
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• pp.175-195
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• 2021

Intimate friendships and a sense of belonging have positive effects on adolescent's psychological adaptation. Belongingness orientation is the motivation to belong. It is divided into growth orientation and deficit-reduction orientation, both of which have different effects on psychological adaptation and interpersonal characteristics. This study was conducted to determine how adolescents' belongingness orientation affected their psychological adaptation and friend networks. Students in their second year of middle school were surveyed both at the beginning and end of the spring semester. Friend networks were measured through network centrality analysis. Multilevel regression analysis produced three major results. The first major result was that the correlations between growth orientation and loneliness and between growth orientation and stress at the beginning of the spring semester was statistically significant even when friend network centrality was included in the analysis model, but the correlation between deficit-reduction orientation and loneliness and between deficit-reduction orientation and stress were not statistically significant. The second major result was that growth orientation significantly predicted friend network centrality at the end of the spring semester. This effect was significant even when friend network centrality at the beginning of the semester and psychological adaptation level at the end of the spring semester were added to the analysis model. The third major result was that the correlation between friend network centrality at the end of the semester and psychological adaptation level was statistically significant even when psychological adaptation levels at the beginning and the end of the semester were included in the analysis model. This study is meaningful in that it had a short-term longitudinal design and empirically demonstrated the relationship between belongingness orientation and psychological adaptation level of adolescents and between belongingness orientation and the development of friend networks. Lastly, we discussed limitations of this study and provided suggestions for future research.