• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1844-1851
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• 1997

Displacement fields and interface stresses are obtained by modifying the potential energy functional with a penalty function which enforces the continuity of stresses at the interface of two-materials. Based on the displacement field and the interface stresses, a new methodology to generate a continuous stress field over the entire domain including the interface of the dissimilar materials has been proposed by combining the L$^{2}$ projection method of stress-smoothing and the Loubignac's iterative method of improving the displacement field. Stress analysis was carried out on two examples which are made of highly dissimilar materials. As a result of the analysis, it is found that the proposed method provides improved continuity of the stress field over the entire domain as well as predicting accurate nodal stresses at the interface. In contrast, the conventional displacement-based finite element method provides significant stress discontinuties at the interfaces. In addition, it was found that the total strain energy evaluated from the improved continuous stress field converge to the exact value as increasing the number of iterations in the proposed method.

• Journal of Korean Public Health Nursing
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• v.17 no.2
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• pp.212-223
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• 2003

The purpose of this study was to investigate work stress and identify the various factors affecting stress in married women in working manufacturing industries. Data were collected between March 31 and June 28, 2003 from 266 married women working in 10 manufacturing industries in Korea. The self-administered questionnaire included general characteristics. social support, and work stress. The data were analyzed using descriptive statistics, t-test, ANOVA, and Cronbach's alpha. SPSS/win 11.0 was used to assist analysis. The results of the study are as follows: 1. Scores for work stress in the field of sub-categories 2. Perceived work stress was significantly different according to salary, behavior type, discomfort related to menstruation, consumption, duty type, job stability, weekly work time and family, 3. Social support had a significant negative relationship with work stress. Accordingly, stress management for married working women will be more successful if interventions not only address each person's unique needs, for example, control of perimenstrual discomforts and health behavior change, but also are accompanied by organizational management strategies and policies, for example, improvement of work environment and nursery facilities.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.5 s.182
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• pp.149-154
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• 2006

The cold expansion method (CEM) is one of the widely used a method to improve the fatigue behavior of materials in aerospace industry. Such improvement is due to the compressive residual stress developed when a tapered mandrel goes through the fastener holes a little smaller than the mandrel. CEM is retarded of crack initiation due to the compressive residual stress developed on the hole surface. Many researchers are studied a finite element analysis of residual stress around fastener hole. But in case of real model, fastener hole has a clamping force after CE. Therefore, it is respected that residual stress distributions should be changed due to clamping forces. In this paper, it was performed finite element analysis of residual stress by clamping force after CE in the plate having adjacent holes. From this study, it has been found that compressive residual stress near the hole increases according to clamping force. Also, the more increase clamping force, the more increases compressive residual stress. However, tensile residual stress increase beyond clamping force area.

• Journal of The Korean Association For Science Education
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• v.32 no.6
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• pp.1063-1071
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• 2012

The purpose of this study is to investigate the relation between the classification ability quotient and cortisol-hormonal change of middle school students. Thirty-three students, second graders in middle school, performed the classification task that can be an indicator of students' classification ability. And then amount of the secreted hormone was analyzed during task performance. The study results were as follows: First, the classification methods of students mostly utilized visual, qualitative. Their classification patterns for each subject were static, partial, and non-comparative. Second, the amount of stress-hormone was secreted from students during the experiment decreased in overall after the free classification. It seemed that student-centered activity relieved stress. Third, the classification ability quotient turned out to be significantly correlated to the stress hormone, which means that there was a close relationship between classification ability and stress level. It was also considered that stress had a positive effect on the improvement of classification ability. This study provided physiologically more accurate information on the stress increased in the learning process than other conventional studies based on reports or interviews. Finally, researchers could recognize the effect of stress in the cognitive activity and the need to find an appropriate level of stress in learning processes.

• Steel and Composite Structures
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• v.42 no.6
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• pp.843-853
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• 2022

The fatigue behavior of welded open rib-to crossbeam joints (ORCJ) in orthotropic bridge structures is investigated using a traction structural stress method. The fatigue behaviors of welded open rib-to crossbeam joints have been a subject of study for decades for ensuring operational safety and future design improvement. A mesh-insensitive combination of traction structural stresses in ORCJ was obtained considering the effect of in-plane shear stress and validated by fatigue test results. The proposed method is advantageous for predicting fatigue cracks that initiate from the crossbeam cutout and propagate along the crossbeam. The investigations carried out with the proposed approach reveal that the normal structural stress decreases with the propagation of fatigue cracks, while the ratio of shear stress to normal stress increases. The effect of shear structural stress is significant for the analysis of fatigue behavior of ORCJ in multiaxial stress states.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.14 no.1
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• pp.120-127
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• 2007

Purpose: This study was done to identify the level of stress, hardiness, and professional burnout of intensive care unit (ICU) nurses and to provide basic data for the qualitative improvement of nursing work achievement in the workplace. Method: The data were obtained from 129 ICU nurses through a questionnaire. Results: Stress showed positive correlation with the level of professional burnout and there was negative correlation between hardiness and professional burnout. Nurses in the group with a high level of stress, and a high level of hardiness reported a low level of professional burnout compared to those in the group with a lower level of hardiness (t=-2.60, p= .012). Nurses in the group with a low level of hardiness and a low level of stress showed a lower level of professional burnout than those with a high level of stress (t=3.51, p= .001). Conclusion: The results show that the high level of stress when coupled with a low level of hardiness of ICU nurses results in a high level of professional burnout. For this reason, it is important for nursing administration to support nurses to reduce levels of stress and the resulting burnout in ICU nurses.

• Safety and Health at Work
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• v.14 no.2
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• pp.207-214
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• 2023

Background: Occupational safety issues related to food delivery riders emerge with evidence of an increase in associated traffic accidents and injuries along with the rapid growth of the online food delivery business. This paper focuses on food delivery riders' job stress and investigates its relationships with both antecedents and risky riding outcomes. Method: Survey data were collected from 279 Taiwanese food delivery motorcycle riders and analyzed using hierarchical regression analysis. Results: The results show that job overload and time pressure positively impact riders' job stress, while self-efficacy slightly reduces job stress. Job stress positively leads to risky driving behavior and distraction. In addition, time pressure can strengthen the impact of job overload on job stress. Riders' risky riding attitude can also strengthen the impacts of job stress on risky riding behaviors and distraction. Conclusion: This paper advances the literature on online food delivery as well as the occupational safety improvement of food delivery riders. Specifically, this study provides insights into the job stress of food delivery motorcycle riders and the effects of job characteristics and risky behavioral consequences.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.1
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• pp.22-31
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• 2003

The compressive residual stress, which is induced by shot peening process, seems to be an Important factor in increasing the fatigue strength. And then it was showed that residual stress was disappearenced at the high temperature. The fatigue charateristic investigation of a SUP9 spring steel processed shot peening is performed by considering the high temperature service conditions in the range of room temperature through $180^{\circ}C$ in the range of stress ratio of 0.3 by means of opening mode displacement. The fatigue resistance characteristics and fracture strength at high temperature is considerable lower than that of room temperature in the early stage and stable of fatigue crack growth region.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.224-225
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• 2005

The lightness of components required on marine and shipbuilding industry is requiring high strength of components. In particular, fatigue failure phenomena, which happen in metal, bring on danger in human life and property. Therefore, antifatigue failure technology takes an important part of current industries. In this study, it was investigated about endurance and fatigue crack propagation rate of according to stress ratio of SMAW commonly using for welding structures in present. Fatigue crack propagation rate(da/dN) of low load(R=0.1) was lower than of high load(R=0.6) for piping weld. And in stage I, ${\Delta}$Kth, the threshold stress intensity factor of the weld under heavy load is higher than under small load. Fatigue life shows more improvement in the weld of stress ratio R=0.l than in the weld of stress ratio R=0.6.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.3
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• pp.76-82
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• 2000

It is well known that during the oxygen cutting process residual thermal stresses are produced in weldment. The local non-uniform heating and subsequent cooling which takes place during any welding process causes complex thermal strains and stresses to finally lead to residual stresses exceed to the yield stress. High tensile stresses combined with applied structural load in the region near the welded joint can given rise to distortion brittle fracture change of the fatigue strength and stress corrosion cracking. The appropriate treatment of the welded component which reduces the peak of he welding residual stresses is believed to lower risk of the fracture during the service of the structure. In this study the impact loading in oxygen cutting frame was applied to reduce the residual stress. After applying the impact loading redistribution of resid-ual stress was measured by cutting method and the effect of fatigue was tested.