• Proceedings of the KWS Conference
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• 2004.05a
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• pp.252-254
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• 2004

Fatigue life a box weldment was predicted with the stress concentration and residual stress using the equation reported. In order to change the stress concentration and residual stress of the box weldment, Post treatments such as smooth grinding of weld bead, weld toe grinding and hammer peening were applied. The fatigue life of the weldment after post treatment clearly increased, which is attributed to the reduction of stress concentration and/or introduction of compressive residual stress at the weld toe. The predicted fatigue life was a relatively good agreement with the experiment for a long fatigue life, while it was underestimated for a short fatigue life.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.137-143
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• 2008

For most bearings, it is a common requirement to have long durability. Especially wheel bearing fatigue life is the most important in automotive quality. The contact fatigue life analysis of automotive wheel bearing considering real raceway rough surface is presented in this paper. Contact stresses are obtained by contact analysis of a semi-infinite solid based on the use of influence functions; the subsurface stress field is obtained using rectangular patch solutions. Mesoscopic multiaxial fatigue criterion which can yield satisfactory results for non-proportional loading is then applied to predict fatigue damage. Suitable counting method and damage rule were used to calculate the fatigue life of random loading caused by rough surface. The life analysis considering real rough surface of wheel bearing raceway is in good agreement with the experimental results.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.181-190
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• 2004

The interest of the fatigue life of rubber components such as engine mounts is increasing according to the extension of warranty period of the automotive components. Automotive engine mounts get damaged due to thermal and mechanical loadings. This paper discusses a fatigue life prediction of the 3-dimensional dumbbell specimens for natural rubber compound considering the effects of maximum strain and heat aging temperature. Displacement controlled fatigue life tests were performed using specimens with different levels of maximum strain and various hardness. The basic mechanical properties test and the fatigue test of aged rubber specimen under normal and elevated temperature were executed. A procedure to predicted the fatigue life of vulcanized natural rubber material based on the maximum strain method was proposed, and then this curve was in good agreement with fatigue test data less than 200% error range.

• Tribology and Lubricants
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• v.15 no.4
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• pp.328-334
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• 1999

Acoustic emission (AE) sensor was used to evaluate the wear-life of CrN-coated steel disks with 1 $\mu\textrm{m}$ and 4 $\mu\textrm{m}$ coating thickness. The relationship between Af and friction signal from scratch test and sliding test was investigated. The first spatting of CrN film was detected by AR signals in the early stage of coating failures, and overall failures by friction signals. Therefore, the conservative design for coating-life should be done using the results of AE signals. Using the percent contact load, the ratio of sliding normal load to the critical scratch load and the number of cycles to failure was measured to predict the wear-life of CrN film. On the wear-life dia-gram the percent contact loads and the number of cycles to failure showed a good linear relationship on the log coordinate. As the load percentage was decreased, the diagram showed that the wear-limits, at which the coated steels survived more than 35,000 cycles, were about 4∼5% of the critical scratch loads.

• Journal of Welding and Joining
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• v.19 no.4
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• pp.406-412
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• 2001

This study is focussed on the numerical prediction of the thermal fatigue life of a ${\mu}BGA$(Micro Ball Grid Array) solder joint. Numerical method is used to perform three-dimensional finite element analysis for Sn-37mass%Pb. Sn-3.5mass%Ag solder alloys during the given thermal cycling. Strain values, along with the result of mechanical fatigue tests for solder alloys were then used to predict the solder joint fatigue life using the Coffin-Manson equation. In this study, a practical correlation for the prediction of the thermal fatigue life is suggested by using the dimensionless variable $\gamma$. As a result. it could be found that Sn-3.5mass%Ag has longer fatigue life than Sn-37mass%Pb in low cycle fatigue. In addition. the result with ${\gamm}ashow$a good agreement with the FEA results.

• The Korean Journal of Health Service Management
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• v.10 no.4
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• pp.239-248
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• 2016

Objectives : The purpose of this study was to examine the mediation effects of self-efficacy on the relationship between life stress and depression in university students to provide a basis for planning nursing interventions to improve the mental health of university students. Methods : Data were collected from September 1 to September 30, 2015 by giving a questionnaire to 272 university students. The instruments for this study were life stress, self-efficacy, and depression. The data were analyzed with descriptive statistics, Pearson's correlation coefficients, and multiple linear regression with the SPSS/WIN 18.0 program. Results : There were significant correlations among life stress, self-efficacy, and depression. Additionally, self-efficacy had a mediating effect on the relationship between life stress and depression. Conclusions : Based on the findings of this study, health management programs focusing on stress management and self-efficacy improvement are highly recommended to promote good mental health in university students.

• Asian Oncology Nursing
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• v.10 no.2
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• pp.156-162
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• 2010

Purpose: The purposes of this study was to compare the meaning in life and death attitude between the participants and nonparticipants of the well-dying education program. Methods: This study adopted the descriptive comparative design. Data were collected by interviewing 85 participants and 94 non-participants of well-dying education. The instruments used for this study were a self-report questionnaire. Results: There were significant differences in age, gender, marital status, health status, and volunteer experience. The program participants showed higher scores in the death attitude than non-participants. There were significant correlations between meaning in life and death attitude in participant group. Death attitude was significantly associated with meaning in life in participant group with 6.0% variance. Conclusion: Based on the results, well-dying education program was effective to prepare good death with more comprehensive vision. Therefore, this program should be served for patient with life-threatening illness by nurse and this is the expended role of oncology and hospice palliative nurses.

• Journal of Korean Public Health Nursing
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• v.18 no.1
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• pp.14-26
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• 2004

Purpose: This study was done to identify the relationship between physical exercise and quality of life in middle-aged adults. Method: The subjects of this study consisted of 251 mid-aged adults who lived in D city and N city. The instrument for this study was exercise performance scale by Kim and QOL scale by Ro. Data were collected form February 20 to March 20. 2003. Result: 1. Among participants. 'good' exercise performance consisted $39.2\%$ and exercise involvement was $41\%$. 2. The quality of life showed positive significant correlation with the exercise performance(r=.21. p=.00). 3. Exercise performance was a predictor of quality of life and $8.3\%$ of the variance explained with exercise performance. Conclusion: The results of this study suggest that further development and applying of exercise performance programs are recommended for quality of life of mid-aged adults. In addition. further research needs to be done to identify relationship with these factors for various age group.

• Journal of the Korean Home Economics Association
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• v.32 no.2
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• pp.61-78
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• 1994

This study was to provide the basis for the development of family life education programs for caregiving families. The data were collected from 374 adult children who were giving care to their older parents in Seoul. Adult children reported experiencing more caregiving problems in the areas of personlities of older parents psychological burden and parents' health than in the areas of caregiver's health and financial burden Women were more likely to experience caregiving problems than men. Adult children indicated higher levels of perceived knowledge on planning for later life psychological characteristics of older parents and keeping good relationships with older parents. They reported more need for knowledge on physical change of older parents and planning for later life while there were less need for knowledge on sharing caregiving roles with others and social service programs. The needs for caregiving education were also identified in the aspects as to participation purposes methods times and agencies. Given these findings this study suggests some practical implications for the development of family life education programs for caregiving families. Further studies should help to advance the development and practice of family life education programs for caregiving families.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.119-123
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• 2000

The characteristics of fatigue life distribution for Carbon/epoxy composite laminates was investigated under tension-tension loading(R=0.1). The statistical nature of the fatigue life of the composite materials was analyzed by Weibull, normal, lognormal distributions As a result, it was observed that the correlation between the experimental results and the theoretical predictions for the fatigue life is good. The distribution of the static ultimate strength has the characteristic of lognormal distribution and distribution of the fatigue life has characteristics of the weibull distribution.