• Journal of Korean Academy of Fundamentals of Nursing
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• v.16 no.2
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• pp.134-143
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• 2009

Purpose: This study was conducted to determine the predictors of health conservation for elders in Korea. Method: Random sampling method was used and data from 113 elders were used for final analysis. Data collection was conducted through the use of questionnaires which were constructed to include Health Conservation Scale, Purpose in Life Test and Self-efficacy Scale. Results: Health conservation of the elders was in the middle range. The elders of this study had few goals towards meaning in life, and were in an existential vacuum state. There was a positive correlation between health conservation, meaning in life and self-efficacy. The significant factors influencing health conservation of elders were meaning in life, education level and gender. These 3 factors explained 30.6% of health conservation of elders. Conclusions: The results indicate that health conservation is an important link with meaning in life in elders. There should be a comprehensive study in the future for in-depth understanding of health conservation of elders.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.205-213
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• 2003

This study describes the mathematical equation of drawdown test model and introduces the experimental test apparatus and procedure to estimate the desorption rate ratio of a filter. The characteristics of a hydraulic filtration system of drawdown test were demonstrated by numerical simulation for various properties of filters and operation conditions. Experiments for three kinds of fuel filters were conducted according to the proposed test method. And the test results of desorption rate ratio were compared with those values anticipated in precedent multipass filtration tests. Experimental results revealed the validation of drawdown test method proposed in this study. Domestic fuel filter yielded high desorption rate ratio comparing with other foreign products, which means that the Beta ratio decreases a lot during the test. The results also showed that filtration system model could be developed including desorption rate ratio to estimate the variable Beta ratio in service life.

• International Journal of Reliability and Applications
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• v.16 no.2
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• pp.123-133
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• 2015

In this paper, the problem of testing exponentiality against net decreasing variance residual lifetime (NDVRL) classes of life distributions is investigated. For this property a nonparametric test is presented based on kernel method. The test is presented for complete and right censored data. Furthermore, Pitman's asymptotic relative efficiency (PARE) is discussed to assess the performance of the test with respect to other tests. Selected critical values are tabulated. Some numerical simulations on the power estimates are presented for proposed test. Finally, numerical examples are presented for the purpose of illustrating our test.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.2
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• pp.122-127
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• 2018

In an attempt to estimate the life projection of LED packages, IESNA published a paper regarding an LED package measurement test method in 2008, and a life projection technical document in 2011, to be used for LED life estimation. IESNA's publications regarding LED package measurement methods were functional, but they were not internationally standardized before 2017. In order to develop a standardized method, the International Standard chose to use the LM-80 as a measurement method for LED life projection in their publication in 2017. Many projection methods have been discussed by the IEC Technical Committee 34 working group, including the method using an exponential function, which reflects lumen degradation characteristics well. This study is designed to explore alternative LED package life estimation methods using an exponential function with statistical analysis, other than the one suggested by the International Standard.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2353-2360
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• 2000

Statistical fatigue properties of metallic materials are increasingly required for reliability design purpose. In this study, static and fatigue tests were conducted and the normal, log-normal, two -parameter Weibull distributions at the 5% significance level are compared using the Kolmogorov-Smirnov goodness-of-fit test. Parameter estimation were compared with experimental results using the maximum likelihood method and least square method. It is found that two-parameter Weibull distribution and maximum likelihood method provide a good fit for static and fatigue life data. Therefore, it is applicable to the static and fatigue life analysis of the spheroidal graphite cast iron. The P-S-N curves were evaluated using log-normal distribution, which showed fatigue life behavior very well.

• Journal of Korean Public Health Nursing
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• v.27 no.1
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• pp.113-128
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• 2013

Purpose: The purpose of this study was to investigate the degree of suicidal risk, meaning in life, and life respect in various ages of patients and identify factors influencing their life respect. Method: The participants were 229 patients in a public hospital who completed questionnaires. Data were analyzed using descriptive statistics, t-test, Fisher's exact test, ANOVA with Duncan post hoc test, and multiple regression. Results: There was a negative correlation between the meaning of life and life respect in the old age group (r=-.23, p=.02) and all subjects (r=-.14, p=.01) after controlling for age. Factors significantly influencing life respect were gender (${\beta}$=0.11, p=.050) and educational status (${\beta}$=-0.17, p=.022), and the multiple regression model explained 16.7% of the variance in all subjects (p<.001). In the early adulthood group, factors significantly influencing the life respect were gender (${\beta}$=0.18, p<.001) and suicidal thoughts (${\beta}$=0.21, p=.028), and the multiple regression model explained 6.8% of variance in all subjects (p=.001). Conclusion: The results of this study suggest that suicidal prevention and educational programs for increasing an appreciation of life should consider subject's characteristics, such as gender and educational status.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.47
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• pp.1-10
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• 1998

Testing high reliability devices under nomal operating condition is difficult, because the devices are not likely to fail in the relatively short time available for tests. For most applications it is necessary to accelerate the causes of failure by increasing a stress above its nomal value. Previous accelerated life test(ALT) plans have shown how to find optimum allocation, lowest stress and sample size subject to minimizing the variance of mean life estimator. In these ALT plans, the highest acceptable test-stress was assumed to be specified in advance by the experimenter but there is no guidance for selecting it. This assumption is, however, inappropriate for many applications. Testing devices at too-high stress levels can invalidate the extrapolation model, or introduce failure mechanisms that are not anticipated under nomal operating conditions. In this paper, we propose new 4:2:1 compromise plans using Min-Max method to minimize this risk and present minimized test-stress levels(max, middle, min), and find sample allocation based on Min-Max 4:2:1 compromise plans. In result, we compare previous 4:2:1 compromise plans specified maximum test-stress with Min-Max 4:2:1 compromise plans minimized maximum test-stress.

• International Journal of Automotive Technology
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• v.7 no.3
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• pp.353-360
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• 2006

The nominal structural stress calculation method proposed by Radaj has included some problems as follows: (a) How the value of the diameter D is decided in the method; (b) It is not possible to estimate nominal structural stress of the spot welded joints with the balanced sheet in-plane load that no general loads are obtained by FE shell analysis. In this paper, the new method for calculating nominal structural stress was proposed to solve above-mentioned problems. The proposed method calculates the nominal structural stress through the circular plate theory in theory of elasticity. This theoretical analysis uses not only general loads but also nodal displacements around spot welding provided by FE shell analysis as boundary condition. Fatigue test data of various spot-welded joints could be arranged in a narrow bandwidth on S-N chart using the nominal structural stresses calculated by proposed method. The fatigue life prediction method using the proposed method for calculating nominal structural stress is useful for the prior evaluation technique that can predict the fatigue life of spot welding by CAE.

• International Journal of Reliability and Applications
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• v.15 no.2
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• pp.125-150
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• 2014

Accelerated life tests (ALTs) are extensively used to determine the reliability of a product in a short period of time. Test units are subject to elevated stresses which yield quick failures. ALT can be carried out using constant-stress, step-stress, progressive-stress, cyclic-stress or random-stress loading and their various combinations. An ALT with linearly increasing stress is ramp-stress test. Much of the previous work on planning ALTs has focused on constant-stress, step-stress, ramp-stress schemes and their various combinations where the stress is generally increased. This paper presents an optimal design of ramp soak-stress ALT model which is based on the principle of Thermal cycling. Thermal cycling involves applying high and low temperatures repeatedly over time. The optimal plan consists in finding out relevant experimental variables, namely, stress rates and stress rate change points, by minimizing variance of reliability function with pre-specified mission time under normal operating conditions. The Burr type XII life distribution and time-censored data have been used for the purpose. Burr type XII life distribution has been found appropriate for accelerated life testing experiments. The method developed has been explained using a numerical example and sensitivity analysis carried out.

• Journal of the Korean Home Economics Association
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• v.31 no.3
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• pp.29-46
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• 1993

The purpose of this study were to investigate the relation between home management ability and family life satisfaction of home makers, and to find out variables which influence them. The data were collected though the questionnaire whose respondent were 408 home makers in Kwang Ju and Kang Reung. The data were analyzed by various statistical method such as Cronbach's coefficient, factor analysis, frequency, percentage, mean, F-test, t-test, Duncan's multiple range test, regression analysis and path analysis. The results were as follow. 1. Home management ability score showed 68.5. Influential variables on home management ability were the level of education (husband and wife), occupation of husband and income as sociodemographic variables, and degree of resourcefulness recognition and of communication as psychological variables. 2. Family life satisfaction score showed 74.6. Influential variables on home management ability were the level of education (husband), occupation of husband and income as sociodemographic variables, and degree of resourcefulness recognition, of communication and of stress recognition as psychological variables. 3. The degree of communication was the highest influential variable to have influence on family life satisfaction. And the degree of resourcefulness recognition, of stress recognition, occupation of husband and wife, level of education(husband), number of children were variables to have directly and/or indirectly influence on family life satisfaction.