• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1862-1870
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• 2020

The purpose of this study is to investigate the effect of welding residual stress on operating stress in designing a nuclear turbine welded rotor. A two-dimensional axisymmetric finite element model is employed to calculate the residual stress before and after post weld heat treatment (PWHT), and then the superposition of residual stress after PWHT and operating stress at normal speed and overspeed were discussed. The investigated results show that operating stress can be affected significantly by welding residual stress, and the distribution trend of superposition stress at the weld area is mainly determined by welding residual stress. The superposition of residual stress and operating stress is linear superposition, and the hoop stress distribution of superposition stress is similar with the distribution of residual stress. With the increasing overspeed, the distribution pattern of the hoop superimposed stress remains almost unchanged, while the stress level increases.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.1
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• pp.19-24
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• 2012

This paper presents the results of finite element analysis for the effects of hydrostatic test and operating condition on the weld residual stress at dissimilar metal weld of a pressurizer safety nozzle in a nuclear power plant. For the study, the weld residual stress at ambient condition was analyzed using ABAQUS in the first place. After the weld residual stress analysis, the hydrostatic test condition and operating condition was applied to the same model one after another. The weld residual stress was observed to change due to the successive hydrostatic test and operating condition. The axial residual stresses on inner surface of the dissimilar metal weld and HAZ region were decreased by hydrostatic test and operating condition, which gives beneficial effect on preventing primary water stress corrosion cracking.

• The Journal of the Korea Contents Association
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• v.13 no.12
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• pp.291-298
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• 2013

This study is a cross-sectional descriptive survey done to identify the relationship between job stress and fatigue in operating room nurses. Data were collected by surveying 124 operating room nurses who were working in operating rooms at two advanced general hospitals and five general hospitals in G city in the province of C, and the survey was conducted by questionnaires. The data were analyzed by descriptive statistics, t-test, ANOVA, and Pearson's correlation coefficient. The level of job stress and fatigue were 3.64(0.45), and 3.46(0.60). In case of job stress in operating room nurses, there was statistically meaningful difference according to hospital type, and their fatigue levels showed statistically meaningful difference according to types of hospital, work motivation, and subjective health condition. There was positive correlation(r=0.47, p=<.001) between operating room nurses' job stress and fatigue. Therefore, this study has significance in the respect that it identified the relationship of job stress and fatigue in operating room nurses, and it will be used as the basis to develop job stress intervention program for operating room nurses.

• Korean Journal of Adult Nursing
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• v.19 no.1
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• pp.1-11
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• 2007

Purpose: To identify the effects of the aromatherapy on stress of nurses working in operating room. Methods: The study design was nonequivalent control-group pretest-posttest design. The subjects were 45 nurses working in the operating room. Experimental group were 24 nurses in G Hospital and control group were 21 nurses in U Hospital. All of the subjects were measured of the subjective stress, stress responses and the job stress. For aromatherapy, lavender, bergamot, and ylang were mixed in the ratio of 2 : 2 : 1. Results: 1) "The subjective stress of experimental group is lower than that of the control group" was supported (t=-2.70, p=.01). 2) "The stress responses of experi-mental group is lower than that of the control group" was supported (t=-2.49, p=.01). 3) "The job stress of experimental group is lower than that of the control group" was supported (t=-7.97, p=.00). Conclusion: This study suggested that such aroma inhalation method could be effective on stress of nurses working in operating room.

• Korean Journal of Occupational Health Nursing
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• v.21 no.3
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• pp.229-238
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• 2012

Purpose: The purpose of this study was to measure the fatigue of operating room nurses and examine factors contributing to their fatigue. Methods: The subjects of this study were 115 nurses who worked in operating rooms of three hospitals. Data were collected from September 15, 2009 to September 30, 2009. Fatigue and job stress were measured by using the Symptom's Fatigue Scale and the job stress measurement tools in operating room nurses. Results: The mean score of fatigue level was $3.10{\pm}0.61$. We analyzed fatigue according to characteristics of subjects and found that there were significant differences in marital status, number of children and sleeping hours in general characteristics. Career, daily participation hours in the surgery relating to job related characteristics. Significant positive correlations were found between job stress and fatigue(r=.233, p= .012). Three significant variables influencing fatigue of operation rooms nurses were job stress, daily participation hours in the surgery, and sleeping hours (Adj. $R^2$=0.284, F=4.773, p<.001). Conclusion: An integrative care program that takes job stress, daily participation hours in the surgery and sleeping hours into consideration is essential to reduce fatigue in operating room nurses.

• Journal of Korean Clinical Nursing Research
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• v.20 no.1
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• pp.102-112
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• 2014

Purpose: The purpose of this study was to identify the effects of foot bath therapy on operating room (OR) nurses' lower extremities edema, stress, and fatigue. Methods: This study used a randomized control group non-synchronized design. The data were collected from August to October 2013, and a total of 50 OR nurses in an university hospital in U Metropolitan City participated in the study: 25 nurses for the experimental group and 25 for the control group. The experimental group received foot bath in which feet were soaked in $40^{\circ}C$ water and immersed up to ankle line for 20 minutes per a day for 12 times. Results: There were significant decrease in the calf edema, physical stress, and fatigue between pre and post foot bath therapy. Conclusion: The findings of this study show that foot bath had the effect in decreasing lower extremities edema, stress, and fatigue among OR nurses. Foot bath therapy, therefore, is suggested as a comfort and easy-to-use method in clinical setting to reduce OR nurses' lower extremities edema, stress, and fatigue.

• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.17-22
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• 2009

Thermal stress and elastic creeping stress analysis was conducted by finite element method to simulate start-up process of a boiler header of 500MW standard fossil power plant. Start-up temperature and operating pressure history were simplified from the real field data and they were used for the thermal stress analysis. Two kinds of thermal stress analysis were considered. In the first case only temperature increase was considered and in the second case both of temperature and operating pressure histories were considered. In the first analysis peak stress was occurred during the temperature increase from the room temperature. Hence cracking or fracture may occur at the temperature far below the operating maximum temperature. In the results of the second analysis von Mises stress appeared to be higher after the second temperature increase. This is due to internal pressure increase not due to the thermal stress. When the stress components of radial(r), hoop($\theta$) and longitudinal(z) stress were investigated, compression hoop stress was occurred at inner surface of the stub tube when the temperature increased from room temperature to elevated temperature. Then it was changed to tension hoop stress and increased because of the operating pressure. It was expected that frequent start-up and shut-down operations could cause thermal fatigue damage and cracking at the stub tube hole in the header. Elastic-creeping analysis was also carried out to investigate the stress relaxation due to creep and stabilized stress after considerable elapsed time. The results could be used for assessing the creep damage and the residual life of the boiler header during the long-tenn service.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1159-1168
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• 2013

In pressurized water nuclear reactors (PWRs), the reactor pressure vessel (RPV) upper head contains penetration nozzles that use a control rod drive mechanism (CRDM). The penetration nozzle uses J-groove weld geometry. Recently, the occurrence of cracking in alloy 600 CRDM penetration nozzle has increased. This is attributable to primary water stress corrosion cracking (PWSCC). PWSCC is known to be susceptible to the welding residual stress and operational stress. Generally, the tensile residual stress is the main factor contributing to crack growth. Therefore, this study investigates the effect on weld residual stress through different analysis methods for normal operating conditions using finite element analysis. In addition, this study also considers the effect of repeated normal operating condition cycles on the weld residual stress. Based on the analysis result, this paper presents a normal operating condition analysis method.

• Journal of Korean Clinical Nursing Research
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• v.22 no.1
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• pp.38-45
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• 2016

Purpose: The purpose of this study was to understand the effects of verbal violence experience, social support, and coping patterns on job stress among operating room(OR) nurses. Methods: The participants were 214 operating room nurses in general hospitals. Data were collected from April 1st to May 1st in 2013 and were analyzed using a multiple regression. Results: The most influencing factor on job stress for OR nurses was verbal violence experience from doctor(${\beta}=.35$), and verbal violence experience from nurse (${\beta}=.27$) followed. Social support from co-workers was a significant factor in decreasing job stress (${\beta}=-.22$). Those three factors explained 43.0% (F=54.76, p<.001) of OR nurses' job stress. Conclusion: The findings of this study revealed that doctors' and nurses' verbal violence increased job stress of OR nurses and social support from co-workers was found decreasing OR nurses' job stress. The results of the study provides an necessity for developing an effective program for minimizing job stress of OR nurses caused by work place verbal violence.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.276-287
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• 1990

In this paper research result of transient thermal stress analysis of power plant turbine rotors for life prediction under severs operating conditions is presented. Galerkin's recurrence scheme is used for numerical solution of discretized FEM equation of transient heat conduction equation. Boundary conditions for the equation and operating conditions are intensively investigated for accurate life prediction of turbine rotors in operation. A computer program for on-site application is developed and tested. Distribution of thermal stress in turbine rotors during various operating condition is analyzed with the program and it is found that the peak thermal stress appears during cold stage conditions at the first stage of high pressure rotors.