• Journal of the Korean Statistical Society
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• 제32권1호
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• pp.25-32
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• 2003

In this paper, we define the mean life process for the right censored data and show the asymptotic equivalence between two kinds of the mean life processes. We use the Kaplan-Meier and Susarla-Van Ryzin estimates as the estimates of survival function for the construction of the mean life processes. Also we show the asymptotic equivalence between two mean residual life processes as an application and finally discuss some difficulties caused by the censoring mechanism.

• Communications for Statistical Applications and Methods
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• 제7권3호
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• pp.789-798
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• 2000

The mean residual function is the expected remaining life of an item at age x. The problem of trend change in the mean residual life is great interest in the reliability and survival analysis. In this paper, we develop a family of test statistics for testing whether or not the mean residual life changes its trend. The asymptotic normality of the test statistics is established. Monte Carlo simulations are conducted to study the performance of our test statistics.

• International Journal of Reliability and Applications
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• 제3권2호
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• pp.91-98
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• 2002

A class of life distributions, whose mean residual life keeps stable at its earlier phase and then starts to decrease in time, is proposed to model the life of an element haying survived its burn-in. A strongly consistent estimator and a nonparametric testing procedure are developed to locate the occurrence of the change-point of the mean residual life. Finally, some numerical simulations are employed to be an illustration as well.

• 대한기계학회논문집A
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• 제23권11호
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• pp.1970-1981
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• 1999

The low-cycle fatigue behaviour of a SiC-particulate-reinforced Al-Si cast alloy with two different volume fractions has been investigated from a series of strain-control led fatigue tests with zero and nonzero tensile mean strains. The composites including the unreinforced matrix alloy, exhibited cyclic hardening behaviour, with more pronounced strain-hardening for the composites with a higher volume fraction of the SiC particles. For the tensile mean strain tests, the initial high tensile mean stress relaxed to zero for the ductile Al-Si alloy, resulting in no influence of the tensile mean strain on the fatigue life of the matrix alloy. However, tensile mean strain for the composite caused tensile mean stresses and reduced fatigue life. The pronounced effects of mean strain on the low-cycle fatigue life of the composite compared to the unreinforced matrix alloy were attributed to the initial large prestrain and non-relaxing high tensile mean stress in the composite with very limited ductility and Cyclic plasticity. Fatigue damage parameter using strain energy, density efficiently accounted for the mean stress effects. Predicted fatigue life using the damage parameter correlated fairly well with the experimental life within a factor of 3. Also, the fatigue damage parameter indicated the inferior life in the low-cycle regime and superior life in the high-cycle regime for the composite, compared to the unreinforced matrix alloy.

• 품질경영학회지
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• 제26권4호
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• pp.101-110
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• 1998

The mean residual life function is the expected remaining life of an item at age $\chi$. The problem of trend change in the mean residual life is great interest in the reliability and survival analysis. In this paper we develop a new test statistic for testing whether or not the mean residual life changes its trend based on a complete sample. Monte Carlo simulations are conducted to compare the perfor mance of our test statistic with that of previously known tests.

• 품질경영학회지
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• 제23권3호
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• pp.93-101
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• 1995

We present a brief survey concerning the relations between mean residual life and failure rate. Change points of mean residual life and failure rate are known to be different in general and we explore such situations in this paper. A few parametric models which show bathtub-shaped failure rate are examined in details, including the shape of its corresponding mean residual life function. We give some graphical comparisons of trend changes of mean residual life and failure rate for various choices of parameters for each parametric model.

• Journal of the Korean Data and Information Science Society
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• 제15권4호
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• pp.965-971
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• 2004

In this paper we consider several nonparametric estimators for the mean residual life by using the partial moment approximation under the proportional hazard model. Also we compare the magnitude of mean square error of the proposed nonparametric estimators for mean residual life under the proportional hazard model.

• 지역사회간호학회지
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• 제8권1호
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• pp.74-88
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• 1997

The purpose of this study was to identify the relationship between perceived social support and the quality of life of cancer patients receiving gene therapy. The subjects for this study were 50 cancer patients receiving gene therapy at two general hospital in Seoul. The data were collected during the period from October 14, 1996 to November 11, 1996. The perceived social support was measured by the family support scale made by Hyun Sook Kang, by the medical support of life scale developed by Ok Soo Kim. The quality of life scale developed by Bang-Whal-Ran was used, among the questionnaire, physical factors was developed by U.S.A National Conference on Cancer Nursing. The data was analysed by the SAS statistical program. Percentile, means and standard deviations, t -test, ANOVA, Scheffe test, Pearson correlation were utilized for analysis. The results of this study were as follows. 1. The mean score of the perceived social support of the subjects was 83.66, the item score was 3.8. 1) The mean score of the perceived family support of the subjects was 44.96, the item mean score was 4.5. 2) The mean score of the perceived professional medical support of the subjects was 38.70, the item mean score was 3.2. 2. The mean score of quality of life of the subjects was 120.38, the item mean score was 3.17. For each factor in quality of life scale, the mean score was follows: for attitude toward life, 3.95, for familial relationship and financial status, 3.53, for social activity 3.24, for emotional status, 3.08, for healthy perceptive, 2.90, for physical symptom, 2.80. 3. The result of the analysis of the relationship between perceived social support and quality of life showed a positive correlation(r=.4853, p=.0004). Therefore, the higher the perceived social support of the patients, the higher the quality of life. 1) The result of the analysis of the relationship between perceived family support and quality of life showed significant correlation(r=. 3566, p=.0110). Therefore the higher the perceived family support of the patients, the higher the quality of life. 2) The result of the analysis of the relationship between perceived professional medical support and quality of life showed significant correlation (r=.4477, p=.0011). Therefore, the higher the perceived professional medical support of the patients the higher the quality of life. 4. There was a significant difference in perceived social support according to sex(F=2.1437, p= .0371), others coping non-family (F=2.4863, p=.0164) and duration of treatment (F=4.16, p=.0218). 5. There was a significant differance in quality of life according to sex(F=2.6932, p=.0097), degree of education(F=2.3610, p=.0223), others coping non-family(F=2.0502, p=.0458). In conclusion, this study revealed that social support is an important factor that associated with the quality of life in cancer patients receiving gene therapy.

• 성인간호학회지
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• 제14권4호
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• pp.501-509
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• 2002

Purpose: This study was performed to identify the illness intrusiveness, quality of life, and their relationships in patients with chronic liver disease. Method: Data was collected using scales of illness intrusiveness developed by Devins et al and Korean health related quality of life (KoQoLS) developed by Shim et al to measure the illness intrusiveness and quality of life from 141 chronic liver disease patients. Result: The total mean score of illness intrusiveness was $38.85{\pm}18.45$. The domain of illness intrusiveness which showed the highest mean score was health ($4.60{\pm}2.02$), and the lowest mean score domain was relationship with spouse ($20.4{\pm}1.69$). The subcategory of KoQoLS which showed the highest mean score was bodily pain ($6.96{\pm}2.98$), and the lowest mean score subcategory was vitality ($2.75{\pm}1.20$). There were negative relationships between illness intrusiveness and KoQoLS in all subcategories. Abovel all, Illness intrusiveness had the strongest negative relationship with role limitation (r=-0.641) among the KoQoLS subcategories. Conclusion: Because the illness intrusiveness had negative influence on the quality of life in patients with chronic liver disease, further research will need to specify detailed illness intrusiveness and to explore influencing factors on quality of life in them.

• 한국도로학회논문집
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• 제14권5호
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• pp.11-19
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• 2012

PURPOSES: The new methodology is proposed for estimation of long-term performance and pavement life based on the national highway database in Daejeon area. Furthermore, this study tried to verify the applicability of performance estimation using NHPCI (National Highway Pavement Condition Index) on tendency of pavement deterioration as time goes by under Korean road environments. METHODS: Reliability theories are applied to estimate the mean life and to determine the appropriate distribution using 3 levels of traffic loads (high, medium, low) based on maintenance and rehabilitation history data for 15 years. RESULTS: As a result, Lognormal distribution is suitable for explanation of pavement lifetime in Daejeon area regardless of traffic loads. In addition, we found that the results of mean life and maintenance timing based on NHPCI for the pavement sections of 3 levels of traffic loads are available. CONCLUSIONS: Based on this study, it was found that mean life of high, medium and low levels of traffic loads are about 8.1 years, 12.2 years and 12.7 years, respectively. Higher level of traffic loads shorten the pavement mean life.