• Journal of the Korean Data and Information Science Society
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• 제23권4호
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• pp.843-850
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• 2012

The inferences of data obtained from periodic inspection and type I censoring for the three step stress accelerated life test are studied in this paper. The failure rate function that a log-quadratic relation of stress and the tampered failure rate model are considered under the exponential distribution. The optimal stress change times which minimize the asymptotic variance of maximum likelihood estimators of parameters is determined and the maximum likelihood estimators of the model parameters are estimated. A numerical example will be given to illustrate the proposed inferential procedures.

• Journal of Ginseng Research
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• 제44권2호
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• pp.267-273
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• 2020

Background: Continuous exposure to high temperatures can lead to heat stress. This stress response alters the expression of multiple genes and can contribute to the onset of various diseases. In particular, heat stress induces oxidative stress by increasing the production of reactive oxygen species. The liver is an essential organ that plays a variety of roles, such as detoxification and protein synthesis. Therefore, it is important to protect the liver from oxidative stress caused by heat stress. Korean ginseng has a variety of beneficial biological properties, and our previous studies showed that it provides an effective defense against heat stress. Methods: We investigated the ability of Korean Red Ginseng and Korean black ginseng extracts (JP5 and BG1) to protect against heat stress using a rat model. We then confirmed the active ingredients and mechanism of action using a cell-based model. Results: Heat stress significantly increased gene and protein expression of oxidative stress-related factors such as catalase and SOD2, but treatment with JP5 (Korean Red Ginseng extract) and BG1 (Korean black ginseng extract) abolished this response in both liver tissue and HepG2 cells. In addition, JP5 and BG1 inhibited the expression of inflammatory proteins such as p-NF-κB and tumor necrosis factor alpha-α. In particular, JP5 and BG1 decreased the expression of components of the NLRP3 inflammasome, a key inflammatory signaling factor. Thus, JP5 and BG1 inhibited both oxidative stress and inflammation. Conclusions: JP5 and BG1 protect against oxidative stress and inflammation induced by heat stress and help maintain liver function by preventing liver damage.

• 대한가정학회지
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• 제35권1호
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• pp.429-442
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• 1997

This study present s and tests a casual model of cohesion adaptability the level of stress recognition coping starategies and quality of life for employed wives and unemployed wives. For the data set 205 employed wives and 200 unemployed wives living in Pusan were chosen. The data were analyzed using M, SD, t-test multiple regression and path analysis. The findings of this study are as follows; First There level of stress recognition and quality of life are higher for employes wives than unemployed wives. Cohesion is higher for employed wives. Whereas adaptability is higher for unemployed wives than employed wives. Employes wives are greater use of coping starategies than unemployed wives. Second For employes wives adaptability the level of stress recognition and coping starategies have significant direct effect on quality of life. Besides wife's level of education age of the youngest child working hours employment motivation and cohesion have significant indirect effect on quality of life. For unemployed wives cohesion adaptability and level of stress recognition have signficant direct effect on quality of life. Besides wife's level of education number of children religion and husband's housework participation are indirectly associated with quality of life. From these results the proposed model is generally supported by the data.

• Communications for Statistical Applications and Methods
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• 제23권4호
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• pp.269-285
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• 2016

In this paper, a simple step-stress accelerated life test (ALT) under progressive type-II censoring is considered. Progressive type-II censoring and accelerated life testing are provided to decrease the lifetime of testing and lower test expenses. The cumulative exposure model is assumed when the lifetime of test units follows an extension of the exponential distribution. Maximum likelihood estimates (MLEs) and Bayes estimates (BEs) of the model parameters are also obtained. In addition, a real dataset is analyzed to illustrate the proposed procedures. Approximate, bootstrap and credible confidence intervals (CIs) of the estimators are then derived. Finally, the accuracy of the MLEs and BEs for the model parameters is investigated through simulation studies.

• 대한간호학회지
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• 제40권3호
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• pp.389-399
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• 2010

Purpose: The aim of this study was to construct a structural equation model that would further explain the mental health status of Korean immigrants living in Canada. Methods: Survey using a structured questionnaire was conducted with 386 people in Canada (Vancouver and Toronto). Six instruments were used in this model. The analysis of data was done with both SPSS 14.0 for descriptive statistics and AMOS 5.0 for covariance structure analysis. Results: Based on the constructed model, physical health status, immigrant life stress, self esteem, and quality of life were found to have significant direct effect on mental health. In addition, factors such as physical health status, immigrant life stress, quality of life, English proficiency, family cohesion and social support were found to indirectly affect mental health. The final modified model yielded Chi-square=34.79 (p<.001), df=13, $x^2$/df=2.68, GFI=0.98, AGFI=0.94, NFI=0.95, PNFI=0.44, PGFI=0.35, RMSE=0.07 and exhibited good fit indices. Conclusion: This structural equation model is a comprehensive theoretical model that explains the related factors and their relationship with mental health in Korean immigrants. Findings of this study can contribute to the designing of an appropriate prevention strategy to further improve the mental health of immigrants in Canada.

• Child Health Nursing Research
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• 제23권3호
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• pp.279-291
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• 2017

Purpose: The aim of this study was to explore how characteristics of ADHD children affect social support for mothers, parenting stress, parenting sense of competence, coping, and quality of life. The conceptual model was based on the Lazarus and Folkman's stress-evaluation-coping theory. Methods: Data were collected 208 mothers of children with ADHD. Data were analysed using SPSS 18.0 and AMOS 18.0 programs. Results: The proposed model was good fit for the data based on the model fit indices. Parenting stress, parenting sense of competence and coping directly affected quality of life but characteristics of the children and social support had only an indirect effect. The explanatory power of these variables was 52.1%. Conclusion: The results of this study indicate that nursing strategies to increase social support for mothers with ADHD children, lowers parenting stress, improves parenting sense of competence, and guides the parents to choose appropriate coping. In particular, as social support has the strongest influence on the quality of life, it is necessary to develop nursing intervention programs that utilize social support for parents with ADHD children.

• 대한기계학회논문집
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• 제15권2호
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• pp.596-603
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• 1991

Fatigue life prediction of pressure vessel is studied analytically using cumulative damage models and linear elastic fracture mechanics method. The stresses are analyzed by finite element method. During operation, the maximum stress occurs at the outside of neck region while fatigue analysis indicates that the bottom of nozzle part has the shortest fatigue life. Previously proposed fatigue life prediction equation and cumulative damage model are modified successfully by introducing reference fatigue modulus. It is found that the modified life prediction equation and damage model are useful for lower stress level application.

• Structural Engineering and Mechanics
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• 제66권2호
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• pp.151-160
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• 2018

With the aim to evaluate the fatigue damage accumulation and predict the residual life of engineering components under variable amplitude loadings, this paper proposed a new strain energy-based damage accumulation model by considering both effects of mean stress and load interaction on fatigue life in a low cycle fatigue (LCF) regime. Moreover, an integrated procedure is elaborated for facilitating its application based on S-N curve and loading conditions. Eight experimental datasets of aluminum alloys and steels are utilized for model validation and comparison. Through comparing experimental results with model predictions by the proposed, Miner's rule, damaged stress model (DSM) and damaged energy model (DEM), results show that the proposed one provides more accurate predictions than others, which can be extended for further application under multi-level stress loadings.

• 한국가족관계학회지
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• 제21권4호
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• pp.27-50
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• 2017

Objectives: This study was carried out in order to evaluate the overall process that the caregiving stress of parents of adult children with developmental disabilities affected their life satisfaction through the levels of family resilience, and coping styles on the basis of stress-coping-adaptation model of Lazarus and Folkman(1984). Method: For this purpose, the structured survey was conducted by 394 parents of adult children with developmental disabilities. The data was analysed by AMOS 20.0 version. Results: The findings can be summarized as follows: First, the structural equation model(SEM) analysis was conducted in order to examine the various paths that parents' caregiving stress affected their life satisfaction. The model's goodness-of-fit was fine($x^2=225.20$, df=95, p=000. RMSEA=.06, TLI=.95). There were significant relationships between caregiving stress and family resilience(${\beta}=-.36$, p<.001), emotion-focused coping style(${\beta}=.47$, p<.001), life satisfaction(${\beta}=-.53$, p<.001). Second, family resilience and emotion-focused coping showed mediating effects on the relationship between caregiving stress and life satisfaction. Conclusions: The strategies for enhancing family resilience and social services for applying effective coping methods should be expanded in order to diminish the caregiving stress of parents of adult children with developmental disabilities.

• 대한간호학회지
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• 제52권3호
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• pp.324-340
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• 2022

Purpose: This study determined acculturative stress' effect on the life satisfaction of multicultural adolescents based on Roy's Adaptation Model and some earlier studies. Further, it examined the sequential multiple mediating effects of bicultural acceptance attitude, self-esteem, and social withdrawal on life satisfaction. Methods: Participants included 1,163 multicultural adolescents who participated in the sixth Multicultural Adolescents Panel Study. A hypothesis test was conducted using Hayes' Process Macro Model 81. Results: Life satisfaction increased with a decline in acculturative stress. Each of bicultural acceptance attitude, self-esteem, and social withdrawal had a single mediating effect on the relationship between acculturative stress and life satisfaction in multicultural adolescents. The sequential multiple mediating effects of bicultural acceptance attitude and self-esteem were confirmed significant after their impact on the relationship between acculturative stress and life satisfaction was analyzed. Bicultural acceptance attitude and social withdrawal were found to have a significant sequential multiple mediating effect on the relationship, as well. Conclusion: This study's results demonstrate that acculturative stress reduction is critical to improving multicultural adolescents' life satisfaction. Bicultural acceptance attitude, self-esteem, and social withdrawal have a single mediating or sequential multiple mediating effect on the relationship between multicultural adolescents' acculturative stress and life satisfaction. The findings, which highlight mediating effects, indicate that by increasing bicultural acceptance attitude and self-esteem, and reducing social withdrawal, multicultural adolescents' life satisfaction can be improved.