• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2552-2559
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• 2000

Most of ferrous b.c.c weld materials have martensitic transformation during rapid cooling after welding. It is well known that volume expansion due to the phase transformation could influence on the relaxation of welding residual stress. To apply this effect practically, it is necessary to establish a numerical model which is able to estimate the effect of phase transformation on residual stress relaxation quantitatively. For this purpose, the analysis is carried out in two regions, i.e., heating and cooling, because the variation of material properties following a phase transformation in cooling is different in comparison with the case in heating, even at the same temperature. The variation of material properties following phase transformation is considered by the adjustment of specific heat and thermal expansion coefficient, and the distribution of residual stress in analysis is compared with that of experiment by previous study. In this study, simplified numerical procedures considering phase transformation, which based on a commercial finite element package was established through comparing with the experimental data of residual stress distribution by other researcher. To consider the phase transformation effect on residual stress relaxation, the transition of mechanical and thermal property such as thermal expansion coefficient and specific heat capacity was found by try and error method in this analysis. In addition to, since the transformation temperature changes by the kind and control of alloying elements, the steel with many kinds of transformation temperature were selected and the effect of transformation on stress releasement was investigated by the numerical procedures considering phase transformation.

• Journal of the Korea Convergence Society
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• v.9 no.6
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• pp.365-372
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• 2018

This study was conducted to investigate the influence of nursing professional value and career decision self efficacy on senior nursing students' job seeking stress. Subjects were 225 senior nursing students. Data were analyzed using descriptive statistics, Pearson's Correlation Coefficient, multiple regression with SPSS/WIN 22.0. As a result, There was significant positive correlation between nursing professional value and career decision self efficacy and negative correlation between and job seeking stress. Career decision self efficacy was significant factor predicting job seeking stress and accounted for 18% of the variance. Therefore, it is necessary to develop strategies for enhancing career decision self efficacy in order to reduce job seeking stress in senior nursing students.

• Smart Structures and Systems
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• v.23 no.1
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• pp.31-44
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• 2019

The present study investigate the compressive stress, shear stress, tensile stress, vertical electrical displacement and horizontal electrical displacement induced due to a load moving with uniform velocity on the free rough surface of an irregular transversely isotropic functionally graded piezoelectric material (FGPM) substrate. The closed form expressions ofsaid induced stresses and electrical displacements for both electrically open condition and electrically short condition have been deduced. The influence of various affecting parameters viz. maximum depth of irregularity, irregularity factor, parameter of functionally gradedness, frictional coefficient of the rough upper surface, piezoelectricity/dielectricity on said induced stresses and electrical displacements have been examined through numerical computation and graphical illustration for both electrically open and short conditions. The comparative analysis on the influence of electrically open and short conditions as well as presence and absence of piezoelectricity on the induced stresses and induced electrical displacements due to a moving load serve as the salient features of the present study. Moreover, some important peculiarities have also been traced out by means of graphs.

• Journal of Powder Materials
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• v.1 no.1
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• pp.52-59
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• 1994

Since the coefficient of thermal expansion (CTE) of matrix phase is larger about 4 times than that of W particle in tungsten heavy alloy, the thermal stresses due to the CTE difference between the two phases are induced in the alloy during heating and cooling processes. In the present study, a series of W heavy alloy containing various W particle volumes of 0 to 90% is made to investigate the residual stress taking place during cooling process. The CTE and residual stress of the series of alloy are measured by dilatometer and X-ray diffractometer. The residual stress of W particle is in compressive stress irrespective of W particle vol% and tends to increase with decreasing W particle vol% while that of the matrix phase is in tensile stress. The measured residual stress of W particle is about a third of calculated thermal stress. The influence of W particle vol% on the residual stress of W heavy alloy is discussed in terms of the deformation behaviors of W particle and matrix phase.

• Journal of Fisheries and Marine Sciences Education
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• v.23 no.3
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• pp.400-409
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• 2011

The purpose of this study was to investigate the influence of irrational beliefs on parenting stress of mothers with early children. For achieving this purpose, Irrational Belief Test and Parenting Stress Index were administered to 300 mothers with early children in Busan and data from 234 mothers were used for statistical analysis. Collected data were analyzed using Pearson correlation coefficient and stepwise multiple regression analysis. The results of correlational analysis showed that irrational beliefs were positively related to parenting stress. Anxious over-concern factor was related to all parenting stress variables. The results of stepwise regression analysis revealed that 2~4 irrational beliefs significantly influenced parenting stress; sub-factors of parenting stress variable that irrational beliefs had the most effect on was competence factor. Based upon these results, it can be concluded that irrational belief is an important variable which predicts parenting stress of mothers with early children.

• Journal of the Korean institute of surface engineering
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• v.30 no.3
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• pp.191-201
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• 1997

Non-passivated electrolytic tinplates withour conventinal chemical treatment self-oxidize in ambient atmosphere to from yellow stain on the outermost surface during the long-term storage. The degree of yellowness of the stain increased linerly with the oxide thickness due to the interfeefence color of the $SnO_2$ Even though the thickness of the oxide layer was very thin, less than 100$\AA$ , it exerts an undesirable influence on the can-making processes, particularly the stripping behavior after ironing. Investigations were carried out on the morphologies of the coating layer, the changes in oxide thickness during successive can-making processes and the averge friction coefficients with the different oxide thinkness. These oxide layers were broken up and distributed within the bulk tin coating during the ironing process. This redistribution of the oxide layer prvented smooth pressing-aside of the tin coating layer, resulting in an increase in the ironing friction coefficient. As the friction was increased, the residual stress along the can wall thinkness(i.e., the hoop stress) was also increased. Due to both the oxibe layer accumulation, which increased the friction coefficient, and the hoop stress, can stripping efficiency without roll-back is reduced.

• The Journal of Korean Academic Society of Nursing Education
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• v.24 no.2
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• pp.160-167
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• 2018

Purpose: This study was conducted to identify the influence of clinical practicum-related stress, and awareness, and self-efficacy on strength on health promotion behaviors among nursing students. Methods: The subjects were 274 students in nursing college who had experience in a clinical nursing practicum. Data were collected from self-reported questionnaires and were analyzed by independent t-test, ANOVA, Pearson correlation coefficient, and multiple regression analyses. Results: Multiple regression analyses showed that strength self-efficacy and self-awareness on strength significantly affected overall health promotion behaviors. Regarding subscales of health promotion behaviors, self-awareness on strength significantly affected health responsibility and stress management in health promotion behavior when controlling for sociodemographic characteristics, while the subscales of clinical practicum-related stress did not affect health promotion behavior. Conclusion: The recognition of an individual's strength and self-efficacy might be a factor in improving health promotion behaviors among nursing college students, although they suffer from stress during clinical nursing practicum.

• Earthquakes and Structures
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• v.26 no.1
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• pp.31-48
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• 2024

In order to get a better understanding of seismic performance of exterior beam-column joint, reciprocating loading tests with variable loading speeds or axial forces were carried out. The main findings indicate that only few cracks exist on the surface of the joint core area, while the plastic hinge region at the beam end is seriously damaged. The damage of the specimen is more serious with the increase of the upper limit of variable axial force. The deflection ductility coefficient of specimen decreases to various degrees after the upper limit of variable axial force increases. In addition, the higher the loading speed is, the lower the deflection ductility coefficient of the specimen is. The stiffness of the specimen decreases as the upper limit of variable axial force or the loading speed increase. Compared to the influence of variable axial force, the influence of the loading speed on the stiffness degradation of the specimen is more obvious. The cumulative energy dissipation and the equivalent viscous damping coefficient of specimen decrease with the increase of loading speed. The influence of variable axial force on the energy dissipation of specimen varies under different loading speeds. Based on the truss model, the biaxial stress criterion, the Rankine criterion, the Kent-Scott-Park model, the equivalent theorem of shearing stress, the softened strut-and-tie model, the controlled slip theory and the proposed equations, a calculation method for the shear capacity is proposed with satisfactory prediction results.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.52-60
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• 2000

In order to design a reliable machine component efficiently, it is necessary to set up the process of durability analysis using computer simulation technique. In this paper, two methods for dynamic stress calculation, which are basis of durability analysis, are reviewed. Then, a user-oriented dynamic stress analysis program is developed from these two algorithms together with a general-purpose flexible body dynamic analysis and structural analysis programs. Finally, a slider-crank mechanism which has a flexible connecting-rod is chosen to show the special characteristics of these two dynamic stress calculation methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.643-651
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• 2016

The aim of this study was to describe the self-esteem, appearance satisfaction, and job-seeking stress and to investigate the effects of self-esteem and appearance satisfaction on job-seeking stress in nursing and healthcare related students. A total of 515 third and fourth year graduate students were included in this study. The data were collected between May 2 and May 13 of 2016 and analyzed using t-test, ANOVA, Scheffe's test, Pearson's Correlation Coefficient, and multiple regression with SPSS 19.0. The economic state had an influence on self-esteem, appearance satisfaction, and job-seeking stress; however, the motive of application and decision of the department of selection did not have any influence. A positive correlation was found between self-esteem and appearance satisfaction. Moreover, job-seeking stress was negatively correlated with both self-esteem and appearance satisfaction. The strongest predictor of job-seeking stress was self-esteem. Self-esteem, employment-area, satisfaction with major, and college majors accounted for 24.4% of job-seeking stress based on multiple regression analysis. These findings indicate that it is necessary to develop a program that would increase self-esteem and satisfaction with major and decrease job-seeking stress according to college majors and employment-area in nursing and health care related students.