• 대한가정학회지
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• 제45권5호
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• pp.121-133
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• 2007

The purpose of this study was to investigate the psychological wellbeing as applied to the bioecological family life welfare model, concerning individual attributes, family backgrounds, and family processes across the family life cycles. Based on Bronfenbrenner's bioecological perspective, the "bioecological family welfare model", which includes person (individual attributes), context (family background), process (mechanism - family process), and time (the family life cycles), was applied as a research paradigm for this study. The sample for the questionnaire study comprised for 900 families, considering the family life cycle in Busan and the Kyungnam area. The families were categorized into 6 family life cycles based on Duvall and Hill's family life cycle. For the final analysis, 628 families were used. According to the path analysis results, the length of commitment before marriage and self-esteem had significant effects on the stress coping ability. Several individual attributes and family backgrounds such as age, length of marriage, family life cycle, self-esteem and stress coping ability had significant effects on marital adjustment. The family life cycle and age were significant variables on family function. The significant variables on psychological wellbeing were monthly income, length of commitment before marriage, stress coping ability and marital adjustment. The regression model showed that the variables of the individual attributes, context and family process accounted for 51% of the psychological wellbeing. The results show that the suggested research model was significant and effective to explain the mechanism of psychological wellbeing. Individual attributes and family context have an impact on stress coping, marital adjustment, and family function, which in turn affect psychological wellbeing.

• 임상간호연구
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• 제28권3호
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• pp.289-298
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• 2022

Purpose: Nursing stress on life-sustaining treatment of nurses is a significant contributing factor to nursing care performance and patient care outcomes. We need to investigate the factors associated with nursing stress on life-sustaining treatment in hospital settings. The purpose of this descriptive study was to examine the relationship of role perception of life-sustaining treatment and good death perception with nursing stress on life-sustaining treatment among nurses in hospital settings. Methods: Using a cross-sectional study design, we recruited nurses at a hospital located in a metropolitan city in Korea. The nurses completed structured questionnaire questions which were composed of well-validated questionnaires. Descriptive statistics and hierarchical multiple regression model were utilized for data analysis. Results: A total of 205 nurses participated in the study (female 93.2%; aged 20~29 years 63.0%; single status 78.5%). In the hierarchical multiple regression model, there was a significant positive relationship between role perception of life-sustaining treatment and nursing stress on life-sustaining treatment (β=.27, p<.001). Higher education level and working at a ward setting were also significantly related to nursing stress on life-sustaining treatment (β=.13, p<.046 for education level; β=.22, p=.001 for work setting). However, there was no relationship between good death perception and nursing stress on life-sustaining treatment. Conclusion: Education programs to reduce nursing stress on life-sustaining treatment are needed to develop for nurses who have higher role perception of life-sustaining treatment with higher education level working at ward settings in hospitals.

• 응용통계연구
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• 제2권2호
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• pp.61-78
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• 1989

정상조건에서 수명이 상당히 긴 개체의 생명검사(Life Test)를 현실적으로 수행하기 위하여 제안된 충격생명검사에 관하여 고찰하였다. 생명검사의 결과로 얻는 자료의 통계적 분석을 위하여 이미 제안된 모형의 검토와 이들을 일면 포함하는 모형을 제시하고 그에 따르는 통계적 추론 과정을 최대우도추정법과 가중최소자승법을 사용하여 토의하였다. 한편 검사를 계획할 때 발생하는 실험설계의 문제를 검토하고 단순 계단적 충격검사에서 잘려진 자료(Consored Data)를 포함한 경우를 연구하였다.

• 대한산업공학회지
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• 제19권2호
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• pp.15-21
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• 1993

This paper considers the optimal design of accelerated life test in which the stress is linearly increased. It discusses the special case when the life distribution under constant stress follows an exponential distribution and the accelerated equation satisfies the inverse power law. It is assumed that cumulative damage is linear, that is, the remaining life of test units depends only on the current cumulative fraction failed and current stress(cumulative exposure model). The optimization criterion is the asymptotic variance of the maximum likelihood estimator of the log mean life at a design stress. The optimal increasing rate is obtained to minimize the asymptotic variance. Table of sensitivity analysis is given for the prior estimators of model parameters.

• Tribology and Lubricants
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• 제31권6호
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• pp.272-280
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• 2015

Recently, Luu suggested fatigue life equation that uses every term of the Crossland equation with stress gradient effect. Luu’s model, however, has a limit of being unable to coverage small radii that are less than a specified length. Furthermore, rolling model has a very small contact area compared to the rolling element size, and fatigue failure occurs on the small radius such as surface asperity by cyclic loading. Therefore, it is necessary to modify fatigue life equation in order to enable fatigue analysis for a small radius. In this paper, the fatigue life considering a stress gradient effect in rolling contact was obtained using Luu’s modified equation. Fatigue analysis was performed to study the effect of stress gradient on the fatigue life using newly adopted equation and to compare the results with pervious models. In order to do this, a series of simulation such as surface stress analysis, subsurface stress analysis, and fatigue analysis are conducted for two rolling balls of same size that contact each other. Through such a series of processes, the fatigue life can be calculated and equation that is proposed in this paper evaluates the fatigue life in case the contact area is small.

• International Journal of Reliability and Applications
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• 제18권2호
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• pp.45-63
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• 2017

In this paper, we have formulated optimum Accelerated Life Test (ALT) plan for a parallel system with two independent components using masked data with ramp-stress loading scheme and Type-I censoring. Consider a system of two independent and non-identical components connected in parallel. Such a system fails whenever all of its components has failed. The exact component that causes the system to fail is often unknown due to cost and time constraint. For each parallel system at test, we observe its system's failure time and a set of component that includes the component actually causing the system to fail. The stress-life relationship is modelled using inverse power law, and cumulative exposure model is assumed to model the effect of changing stress. The optimal plan consists in finding out the optimum stress rate using D-optimality criterion. The method developed has been explained using a numerical example and sensitivity analysis carried out.

• 여성건강간호학회지
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• 제15권3호
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• pp.231-241
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• 2009

Purpose: This study was designed to construct and test a structural equation model for life satisfaction in grandmothers who were parenting grandchildren Methods: Grandmothers assuming part-time parenting responsibilities for grandchildren were recruited in four cities in South Korea. They were asked to complete a questionnaire through face to face interviews or self reports, and 248 data units were analyzed with Structural Equation Modeling. Results: Model fit indices for the final model revealed a fit at an excellent level, and all of the 12 paths were statistically significant explaining 51% of the variance. Predictors of life satisfaction in the final model were parenting efficacy, perceived health status, parenting stress, amount of parenting, and demographic factors. The new findings of this study were as follows: First, the satisfaction with life of part-time parenting grandmothers was less than that of non-parenting grandmothers. Second, parenting stress and parenting efficacy revealed determinants to life satisfaction. Third, motivation of parenting and amount of parenting affect both parenting stress and parenting efficacy. Conclusion: The value of parenting and the grandmother-adult children relationship quality should also be considered in developing a grandmothers' educational program, because these are the factors which strengthen parenting efficacy and alleviate parenting stress.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권1호
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• pp.45-51
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• 2014

Thermal shock tests at two stress levels were performed to see the life (cycles) of LPF ASSY (low pass filter assembly) at normal stress level. In this case Coffin-Manson relationship is generally used to describe the relationship between the temperature difference and the life, together with the Weibull distribution describing the life at each stress level. So for given data Coffin-Manson is fitted to predict the life at normal stress level. However, different types of models are appropriate for this type of test. Hence, a more appropriate model such as General log-linear model which can also incorporate the duration at the highest and lowest temperatures and acceleration time will be introduced.

• 한국세라믹학회지
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• 제30권3호
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• pp.229-235
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• 1993

Thermal history and thermal stress of alumina specimen, which occured from thermal shock process, were calculated by finite difference method. Stress intensity factor and crack growth in cyclic thermal fatigue were calculated from single thermal shock temperature history and thermal stress. Cyclic thermal life were estimated by bending strength after cyclic thermal shock under critical thermal shock temperature. Calculated stress intensity factor was compared with real experimental thermal fatigue life of specimen. Fatigue life until critical stress intensity factor and real experimental result were comparable.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4166-4178
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• 2021

The Control Rod Drive Mechanism (CRDM) is an essential part of the reactor, which realizes the start-stop and power adjustment of the reactor by lifting and lowering the control rod assembly. As a moving part in CRDM, the latch directly contacts with the control rod assembly, and the life of latch is closely related to the service life of the reactor. In this paper, the relationship between the life of the latch and the step stress, friction stress, and impact stress in the process of movement is analyzed, and the optimization methodology and process of latch life based on the approximate model are proposed. The design variables that affect the life of the latch are studied through the experimental design, and the optimization objective of design variables based on the latch life is established. Based on this, an approximate model of the life of the latch is built, and the multi-objective optimization of the life of the latch is optimized through the NSGA-II algorithm.