• Journal of Ocean Engineering and Technology
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• v.15 no.3
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• pp.100-106
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• 2001

In this study, CT specimens were prepared from Pressure Vessel Steel which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -10$0^{\circ}C$ and -12$0^{\circ}C$ and in the range of stress ratio of 0.05 and 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ${\Delta}K_{th}$ in the early stage of fatigue crack growth (Region I) and stress intensity factor range ${\Delta}K$ in the stable of fatigue crack growth (Region II) was increased in proportion to descent temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN $-{\Delta}K$ in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It was assumed that the fatigue crack growth rate da/dN in proportion to descending temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• Journal of Korean Academy of Nursing
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• v.47 no.6
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• pp.854-863
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• 2017

Purpose: The present study is a descriptive cross-sectional study of cause-and-effect relationship, which used the $7^{th}$ year data of the Panel Study on Korean Children, to investigate the effects of parenting stress, depression, and family interactions of the parents of early school-age children on children's subjective happiness. Methods: The present study included data of 1419 pairs of parents who participated in the mother and father survey of the Panel Study on Korean Children. The effects of parenting stress, depression, and parental family interactions on children's subjective happiness were analyzed as actor and partner effects using path analysis. Results: Parenting stress had an actor effect on depression; maternal parenting stress (${\beta}=-.21$, p<.001) and depression (${\beta}=-.30$, p<.001) had an actor effect on maternal family interaction; and paternal parenting stress (${\beta}=-.18$, p<.001) and depression (${\beta}=-.17$, p<.001) had a partner effect on maternal family interaction. Paternal parenting stress was found to have an actor effect on paternal family interaction (${\beta}=-.30$, p<.001), and parental depression was found to have actor effect (${\beta}=-.23$, p<.001) and maternal depression had a partner effect on paternal family interactions (${\beta}=-.22$, p<.001). Children's subjective happiness was found to have a statistically significant relationship with maternal family interaction (${\beta}=.40$, p<.001). Conclusion: The significance of the study is in its provision of basic data for adjusting parents' family interactions that are closely related to the growth and development of children by confirming the effect of parents' parenting stress, depression, and family interaction on children's subjective happiness.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.715-722
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• 2001

The main purpose of this study is to evaluate early age thermal stresses and to estimate the risk of thermal cracking in the footings of Hyungsan bridge. In this study, stress analyses are performed for several construction stages using the computation of temperature distributions. The stress analysis results show that, not using the embedded pipe cooling, placing the concrete at once for each footings may cause sever thermal cracking. So, the structures should be constructed with one horizontal construction joint. Then the height of each lifts were determined to be 1.50 meters. Using various time intervals between lifts, temperature and stress.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2001.05a
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• pp.129-133
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• 2001

Accelerated life test is a viable method for identifying failure modes, incorporating design changes on an on-going basis during the early stages of automotive development program. The information from tests at high stress levels is extrapolated to obtain estimate of life at normal stress levels. This paper presents a practical method for accelerated life test to achieve a specified accuracy in estimating life at a design stress. Recommended and optimum plan are presented and the plans are illustrated with a simulated test data for the automotive power element example.

• Korean Journal of Human Ecology
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• v.21 no.2
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• pp.213-223
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• 2012

The purpose of this study was to evaluate the relationship between stress, temperament and maternal-fetal attachment in pregnant women. The respondents in this research were 249 pregnant women who were participating in a Parent Education project. Data was collected by way of a questionnaire. A summary of the findings were as follows: Among the pregnant women in this study, total stress level was below the average and maternal fetal attachment level was above the average. The group demonstrating high levels of stress exhibited low level of maternal-fetal attachment when compared to those with low levels stress. Pregnant woman's stress and maternal temperament demonstrated a significant correlation with maternal-fetal attachment.

• Korean Journal of Child Studies
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• v.28 no.3
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• pp.61-75
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• 2007

This study defined awareness of professionalism and job stress in 353 child-care teachers of children with special needs and analyzed the relative contribution of professional awareness to job stress. Teachers showed high awareness of 'ethics' and 'enthusiasm enhancing professionalism', and this awareness correlated highly with professionalism in the 'specialized knowledge and skills' sub-factors. Teachers showed high levels of stress in the 'general duty' and the 'guidance of children with special needs' categories, and this correlated highly with stress caused by 'child-care center management.' The results of canonical correlation analysis indicated that of professionalism sub-factors only the awareness of 'social services' contributed positively to job stress.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.250-255
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• 2004

In this paper, we established baseline information and insight on residual stress relief mechanism associated with furnaced and local PWHT(post weld heat treatment) operation. Based on FEM analysis results, we suggested that furnaced PWHT stress relief mechanism was based on creep relaxation and local PWHT stress relief mechanism involved complicated interactions between plasticity and creep. In case of furnaced PWHT, significant stress relaxation was occurred in the early stage of PWHT. In case of local PWHT, stress relaxation magnitude was increased as PWHT time increased. Finally, We have proposed that detailed furnaced and local PWHT procedure, and qualification criteria to support current codes of practices.

• International Journal of Automotive Technology
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• v.6 no.3
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• pp.285-291
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• 2005

In this paper, the author proposes a fatigue damage parameter of spot welded joints under proportional loading. The proposed fatigue damage parameter is developed based on von Mises' equivalent stress and local structural stress at the edge of spot weld nugget. The structural stress at the edges of the weld nugget in each sheet is calculated using the forces and moments that are determined by finite element analysis. A structural equivalent stress is then calculated by von Mises' equivalent stress equation. The structural equivalent stresses are correlated to experimental fatigue life of the spot welded joints. The proposed parameter is evaluated with fatigue test data of spot welds subjected to multi axial and tensile-shear loads. Sheppard's parameter and Rupp and co-workers' parameter are also evaluated with the same test data to compare with the author's parameter. This proposed parameter presents a better correlation with experimental fatigue data than those of Sheppard's and Rupp and co-workers' parameter. The proposed parameter should be very effective for durability calculations during the early design phase since coarsely meshed finite element models can be employed.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.434-478
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• 2006

Stress waves have been used for geophysical and geotechnical applications for more than 50 years. The early-stage applications were simply based on travel-time measurements of stress waves and limited to site characterization. Currently stress-wave techniques are expanded to monitoring processes for grouting of damaged geotechnical structures, compaction of embankment, and deformational analyses for static geotechnical problems. Seismic techniques used to be good enough for rough estimators of engineering properties. Nowadays, the sophisticated modeling theory of stress-wave propagation substantially improved reliability and accuracy of the seismic techniques. In this paper, difficulties involved in currently available seismic techniques are discussed and analyzed. Herein some recently-developed non-intrusive seismic techniques, which make optimal use of stress waves for further improvement of reliability and accuracy, are also presented.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.3
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• pp.179-195
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• 2009

Scince $^{201}$TI was introduced as a myocardial perfusion imaging agent in the early 1970s, scintigraphic evaluation of myocardial perfusion for the diagnosis of coronary artery disease is a valuable noninvasive diagnostic imaging modality. Stress radionuclide myocardial perfusion imaging is widely accepted to have high diagnostic and prognostic use in the assessment of patients with known or suspected coronary artery disease. With wise use of this nonivasive imaging technique, more patients are referred for stress perfusion imaging. Until now various protocols for stress testing and myocardial imaging were developed and used in worldwide. This article presented various protocols of stress testing and myocardial imaging for clinical use.