• Journal of Power System Engineering
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• v.17 no.4
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• pp.64-71
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• 2013

In this paper, finite element method was used for flow and strength analysis of AZ31 magnesium alloy under friction stir welding. The simulations were carried out by SYSWELD s/w, and the modeling of sheet was doned by unigraphics NX3 s/w. Welding variables for analysis were rotating speed and welding speed of tool. Also two-way factorial design method was applied to confirm the effect of welding variables on maximum temperature and stress of material used. From these results, the increaser welding speed of tool the decreaser maximum temperature, but the increaser maximum stress. Also the increaser rotating speed of tool the increaser maximum temperature, but the decreaser maximum stress. In addition the increaser welding speed of tool and the decreaser rotating speed of tool, the narrower heat effect zone. Finally rotating speed of tool influenced on maximum temperature more than welding speed of tool, and welding speed of tool influenced on maximum stress more than rotating speed of tool from the variance analysis.

• Journal of Korean Society for Quality Management
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• v.23 no.2
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• pp.91-102
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• 1995

For two independent random variables X and Y, the functional R=Pr[X>Y] is of practical importance in reliability. X can be interpreted as the strength of a component subjected to a stress Y, and R is the component's reliability. In this paper nonparametric approach to estimation of R based on censored observations in the strength variables is analyzed and compared by simulations in the moderate sample sizes.

• Advances in aircraft and spacecraft science
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• v.4 no.4
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• pp.467-486
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• 2017

A method for decoupling reliability based design optimization problem into a set of deterministic optimization and performing a reliability analysis is described. The inner reliability analysis and the outer optimization are performed separately in a sequential manner. Since the outer optimizer must perform a large number of iterations to find the optimized shape and size of structure, the computational cost is very high. Therefore, during the course of this research, new multilevel reliability optimization methods are developed that divide the design domain into two sub-spaces to be employed in an iterative procedure: one of the shape design variables, and the other of the size design variables. In each iteration, the probability constraints are converted into equivalent deterministic constraints using reliability analysis and then implemented in the deterministic optimization problem. The framework is first tested on a short column with cross-sectional properties as design variables, the applied loads and the yield stress as random variables. In addition, two cases of curvilinearly stiffened panels subjected to uniform shear and compression in-plane loads, and two cases of curvilinearly stiffened panels subjected to shear and compression loads that vary in linear and quadratic manner are presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1109-1117
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• 2015

The purpose of this study was to examine the job-seeking stress of nursing students according to their critical thinking disposition and self-esteem and the relationship of these variables. The subjects in this study were 332 nursing students. The students got $89.57{\pm}9.77$ in critical thinking; $25.11{\pm}2.58$ in self-esteem; and $46.38{\pm}17.67$ in job-seeking stress. There was a positive correlation between critical thinking and self-esteem(r=.294, p<.001), and critical thinking(r=-.240, p<.001) had a significant positive correlation with self-esteem(r=-.209, p<.001). Critical thinking disposition and self-esteem were identified as the variables to affect job-seeking stress, and the two variables had a 35.2% explainability.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.104-110
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• 2001

The objective of this study is structural analysis of continuous casting mold. A two-dimensional finite element model was developed to compute the temperature distribution, thermal stress and thermal strain behavior for continuous casting mold. Structural analysis was made using thermal analysis result, utilizing transient analysis of ANSYS. This structural analysis results, many variables such as casting speed, cooling condition film coefficient, convection and load condition are considered.

• Proceedings of the Korean Reliability Society Conference
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• 2000.11a
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• pp.411-411
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• 2000

Consider the problem of estimating the reliability of a multicomponent stress-strength system which functions if at least r of the k identical components simultaneously function. All stresses and strengths are assumed to be independent random variables with two parameter Weibull distributions. First, we derive reference priors and probability matching priors which are noninformative priors. We next investigate sufficient conditions for propriety of posteriors under reference priors and probability matching priors. Finally, we provide, using these priors, some numerical results for Bayes estimates of the reliability by applying Gibbs sampling technique.

• Journal of Korean Biological Nursing Science
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• v.4 no.2
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• pp.79-92
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• 2002

This study was aimed to analyze the variables measuring stress and immune responses, to identify the relationship between stress and immune responses, and to find out the effect of nursing interventions associated with stress and immune responses by reviewing thirty-four published articles since 1970 in Korea. The articles were selected in the field of nursing, stress management, and masters or doctoral dissertations and limited to human subject. Among these, the thirty-one articles were published since 1996 and mainly distributed in nursing (44.1%) and medicine(44.1%). The prevailing research design was nonequivalent control pre-post experimental design(41.1%). The research subjects were 55.9% for patients and 44.1% for healthy general persons including 20.6% of university students. To evaluate stress, both physiologic and psychosocial measures were adapted together in 35.3% of the articles. The most frequent two variables measuring stress and immune response were cortisol level(15.9%) and number or activity of natural killer cell(25.9%). The relation between stress and immune responses was positive in 4 articles, negative in 9 cases, and none in 12 cases. Decreased stress and enhanced immune function have been found when massage, abdominal breathing, exercise, relaxation, and touch were provided as nursing interventions. The articles to investigate the relationship between stress and immune function were limited and the tested variables were diverse. Also there was no consistent evidence to correlate the stress and immune function at present. Further studies are needed to construct a valid research design and to investigate the relationship between stress and immune responses. Nursing interventions to decrease stress should be developed to result in the increased immune function and the effect of these interventions would be verified.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1341-1346
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• 2009

In this paper, the technique to reinforce the durability performance of structure using the sensitivity information for the frame structure is applied. The fatigue life calculation for the frame structure is performed from the quasi-static and transient analysis and the characteristics of two methods are compared for the fatigue analysis. Then the reinforcement technique is applied. First, some design variables related to the locations of fatigue failure is selected. Then sensitivities of fatigue life at fracture points with respect to the variation of design variables are calculated and the vector composed of gaps between the target life and initial life cycles is calculated. If the number of fatigue fracture points is same as the number of design variables, the variations of the design variables are calculated from the linear algebraic equation. If not, the variations of the design variables are calculated from the optimization formulation with the constraints.

• Research in Community and Public Health Nursing
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• v.20 no.2
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• pp.113-122
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• 2009

Purpose: The purpose of this study is to explore the effect of aromatherapy on anxiety, depression, and stress. Methods:Medical and nursing literature databases were searched to identify studies comparing aromatherapy with a control group. Results: Thirty-one studies published till September 2008 were included in the analysis. Twenty-two studies showed that aromatherapy generally had positive effects on the anxiety level (ES: 0.61). Thirteen studies showed that aromatherapy has significantly decreased the depression level (ES: 0.91). Seven studies showed that aromatherapy had positive effect on the stress level (ES: 0.78). Further analysis found that aromatherapy was more effective for normal population than for patients group with anxiety and stress. On the contrary, aromatherapy was more effective for patients group than for general population with depression. Conclusion: Aromatherapy had positive effect on anxiety, depression and stress level. But there was no sufficient evidence to show the two different aromatherapy methods and two different period of aromatherapy had different effects due to small sample size and heterogeneity of sample. And it was needed to perform follow-up and further comparative studies.

• The Journal of the Korea Contents Association
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• v.11 no.9
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• pp.414-428
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• 2011

The purpose of this study was to investigate the effects of the elderly long-term care workers' job stress on psychological burnout and organizational effectiveness and the moderating role of social support. For this study, data were collected from 290 long-term caregivers from 50 in-home visitation care facilities in Seoul using structured questionnaires. Collected data were analyzed using hierarchical regression techniques. Results showed that role three job stress variables had positive effects on caregivers' psychological burnout; that two job stress variables(role ambiguity and role conflict) and psycholigcal burnout had negaive effects on caregivers' job satisfaction whereas they had positive effects on caregivers' intent to leave; that workload negatively impacted caregivers' job satisfaction but no effect on their intent to leave; and that two social support variables played moderating roles in the relationship between job stress and psychological burnout and the relationship between job stress and organizational effectiveness.