• Korean Journal of Child Studies
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• v.36 no.4
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• pp.209-227
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• 2015

The present study investigated maternal parenting stress trajectories, using data gathered from the Korean Children Panel Survey. Four factors-monthly income, maternal depression levels, infants' negative emotionality, marital conflict-which were taken from reports made by the mothers' used in this study, were examined as predictors of maternal parenting stress trajectories. The effects of maternal parenting stress trajectories, parenting styles and toddlers' peer interruptive behaviors were also examined. The findings were as follows: First, maternal parenting stress trajectories somewhat increased from the 1st year period to the 4th year period. Second, infants' negative emotionality and marital conflict within the first year were observed to have a connection to the initial level and slope of maternal parenting stress trajectories. Third, maternal parenting stress trajectories predicted positive parenting styles, and parenting styles had a longitudinal impact on toddlers' peer interruptive behaviors at the 5th year period.

• 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.

• Journal of the Korean Home Economics Association
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• v.48 no.10
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• pp.89-103
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• 2010

The purpose of this study was to examine the developmental trajectories of adolescents' internalizing problem behaviors. The data came from 3,188 middle school students through their participation in the Korea Youth Panel Survey(KYPS). Adolescents with a high level of internalizing problem behaviors in the first year showed a rapid decline in these behaviors over time, whereas for adolescents with a low level of these behaviors in the first year the decline was slow. The predictors of the developmental trajectories were related to individual variables, such as gender, self-esteem, self-control, stress, self-stigmatization, and academic achievement. The developmental trajectories of adolescents' internalizing problem behaviors were classified into four groups. The predictors of the patterns of developmental trajectories in adolescents' internalizing problem behaviors appeared to be related to individual variables.

• Korean Journal of Child Studies
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• v.36 no.3
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• pp.77-92
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• 2015

The purpose of this study was to employ the Latent Growth Curve Model to investigate the developmental trajectories of maternal depressive symptoms and to identify predictors that might have an effect on change and the level of developmental trajectories. The results of this study indicated that the maternal depressive levels of a high risk group had increased significantly over the past 5 years. The predictors for these developmental trajectories of maternal depressive symptoms were as follows; birth order, maternal prenatal depressive levels, self-esteem, marital satisfaction, parenting stress and the level of family crisis experienced by the high risk group.

• Journal of Digital Convergence
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• v.15 no.2
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• pp.405-409
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• 2017

The purpose of this study is to obtain basic data to be used in social welfare intervention for relieving psychological burdens caused by job stress in the eco-boomer generation that will be the center of Korean society in future, by estimating job stress change trajectories of the eco-boomer generation in the convergence era, figuring out predicting factors and examining job stress factors that individuals experience, in accordance with the degree of job stress and the changes. This is a longitudinal study using secondary data and for analysis, the Latent Growth Model(LGM) was applied to the 1st year to the 7th year Korean Welfare Panel Data. Self-esteem was one of job stress predicting factors of the eco-boomer generation. Since most of eco-boomers were students in the early measurement period, the level of job stress was low, but over time, the burden of job increased by gradation. This study has significance by providing an empirical basis for predicting factors of job stress changes of the eco-boomer generation to understand job stress in the eco-boomer generation.

• Journal of Korean Academy of Nursing
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• v.50 no.6
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• pp.822-836
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• 2020

Purpose: This study aimed to identify latent classes of behavioral problem trajectories in children with allergic diseases and investigate their predictors. Methods: This study used data from the 5th to 7th Panel Study of Korean Children. The participants included 840 children aged 4~6 years with allergic diseases. Statistical analyses were conducted using latent class growth analysis and multinomial logistic regression. Results: The trajectories of both internalizing and externalizing behavioral problems in children with allergic diseases were classified into five groups, that is deteriorative, recovering, changing 1 (decreasing-increasing), changing 2 (increasing-decreasing), and low state persistent group. For the internalizing behavioral problems, predictors were temperament, father's education, family interaction, and disconnection in peer interaction. For the externalizing behavioral problems, predictors child's gender, temperament, marital conflict, parenting stress, family interaction, and parenting environment. Conclusion: Deteriorative group has high-risk behavioral problems in children with allergic diseases. We suggest to provide interventions considering latent problem trajectories based on ecological environments for allergic children.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.577-580
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• 2003

Stress state of chip formation zone is one of the main problems in metal cutting mechanics. In two-dimensional case this process is usually considered as consistent shears of work material along single of several shear surfaces. separating chip from workpiece. These shear planes are assumed to be trajectories of maximum shear stress forming corresponding slip-line field. This paper suggests new approach to the constriction of slip-line field, which Implies uniform compression in chip formation zone. On the base of given model it has been found that imaginary shear line in orthogonal cutting is close to the trajectory of maximum normal stress and the problem about its determination have been considered. It has been shown that there is a second central slip-line field inside chip, which corresponds well to experimental data about stress distribution on tool rake face and tool-chip contact length. The suggested model could be useful in solution of various problems of machining.

• Bulletin of the Society of Naval Architects of Korea
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• v.3 no.1
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• pp.19-24
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• 1966

The maximum shear stress distribution in a stiffening flat attached to a plat undergoing a single tensile force has been investigated by photoelastic method. In the experiments a photoelastic model, as shown in Fig. 1, has been studied in the fields of a polariscope, as shown in Fig. 2. Fig. 3 shows the isoclinics and Fig. 4 and 5 are stress trajectories of the principal stresses and maximum shear stresses, respectively. Fig. 6 is the isochromatics in light field. The maximum shear stress at each point in the stiffener were determined from the isochromatics in both of light field of light field and dark field. Then the maximum shear stresses were divided by the average shear stress in the model, to obtain the ratio ${\tau}max/{\tau}av$ at each point. Finaly the variations of the ratio ${\tau}max/{\tau}av$ along the horizontal and vertical lines in the stiffener have been plotted, as shown in Fig. 7 and 8. The conclusions reached in this investigation are as follows: (1) The shear stresses transmitted to the stiffener through the juncture are concentrated on the end portions. (2) The maximum shear stress at the ends of the stiffener reaches to about 4 times of average shear stress. (3) The irregularities in the stress distribution are restricted in the end portions of the stiffener.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.3
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• pp.24-28
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• 2005

Stress state of chip formation zone is one of the main problems in metal cutting mechanics. In two-dimensional case this process is usually considered as consistent shears of work material along one of several shear surfaces, separating chip from workpiece. These shear planes are assumed to be trajectories of maximum shear stress forming corresponding slip-line field. This paper suggests a new approach to the constriction of slip-line field, which implies uniform compression in chip formation zone. Based on the given model it has been found that imaginary shear line in orthogonal cutting is close to the trajectory of maximum normal stress and the problem about its determination has been considered as well. It has been shown that there is a second central slip-line field inside chip, which corresponds well to experimental data about stress distribution on tool rake face and tool-chip contact length. The suggested model would be useful in understanding mechanistic problems in machining.

• Journal of Welding and Joining
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• v.28 no.1
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• pp.100-106
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• 2010

In this paper crack propagation analyses in the dissimilar metal weldment of a nozzle were performed using a finite element alternating method (FEAM). A two-dimensional axisymmetric finite element nozzle model was prepared and welding simulation including the thermal heat transfer analysis and the thermal stress analysis was performed. Initial cracks were inserted at weld and heat affected zone in the finite element model which has welding residual stress distribution obtained from the welding simulation. To calculate crack propagation trajectories of these cracks, a new fatigue crack evaluation module was developed in addition to the previous FEAM program. With the new FEAM fatigue crack evaluation module, crack propagation trajectory and crack growth time were calculated automatically and effectively.