• Journal of Aerospace System Engineering
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• v.8 no.3
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• pp.41-46
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• 2014

Fatigue evaluations for the rotor blades of commercial or military rotorcraft have been carried out using the safe life concept since 1950s. Particularly, in the case of a rotor blade made of a composite material, a highly reliable fatigue life could be predicted by evaluation the cumulative damage using combination of fatigue life curve and load spectrum. However, there is a limit in adequately evaluating the strength reducing phenomena caused by damages or defects generated during the manufacturing process or impact damage induced by operational usages, using only the safe life concept. In this study, the fatigue evaluation process based on the damage tolerance concept is described and illustrated by means of successful application to substantiate the retirement time of composite rotor blades.

• Safe Food
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• v.1 no.4
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• pp.50-57
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• 2006

• Journal of Families and Better Life
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• v.14 no.3
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• pp.109-120
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• 1996

While theories of portfolio selection have been developed very little is known about how individuals actually go about constructing their asset potfolios. This study investigates empirically the characteristics of household's assets and which factor associated with risky and safe asset amount. Data used in this study consisted of 2,164 households and the statistics employed to analyze the data are univariate procedure Logit analysis and OLS. The results of this study were as follows: Among 2,164 households 505 housholds(23.3%) had risky assets. Average risky asset amount is 8,351,500 won and average safe asset amount is 7,086,900 won. Region education and occupation of household head home ownership transfer and other income and total expenditure had significant effects on either and other income and total expenditure had significant effects on either household having risky asset or safe asset. Financial income transfer and other income and total expenditure had significantly p sitive relation with the risky asset amount. Whereas age and the occupation of household head the sense of economic wellbeing earned financial tranfer and other income and total expenditure had significantly positive relation with safe asset amount.

• Journal of Korean Society for Quality Management
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• v.35 no.2
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• pp.45-52
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• 2007

The danger of self-ignition of single base propellants will increase with time. Therefore, a good prediction of the safe storage time is very important. In order to determine the remaining shelf-life of the propellants, the content of stabilizer is determined. The propellants stored under normal storage conditions about 10 to 18 years were investigated and accelerated aging test was carried out by storing propellant sample at higher temperature. Finally, we analyzed the results by various methods in order to show the best way to predict the realistic shelf-life. The safe storage life of the propellants will be 24 years, at least 15 years. In case of applying Arrhenius's law, using the reaction rate constant at 28$^{\circ}C$ to 30$^{\circ}C$ to predict the shelf-life by accelerated aging test is reasonable for a good prediction.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.5
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• pp.542-548
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• 1997

In this study an evaluation method of fatigue strength of membrane type LNG tank is presented with FEM analysis and experimental approach of seam and raised edge welds. The study contains the following : l)FEM analysis of test specimens 2)Fatigue tests of seam and raised edge welds 3)Estimation of cumulative damage factor of the welds on the basis of safe life design concept complying with the rules of classification society 4)Review of the effect of mean stress on the fatigue strength 5)Modelling of fatigue life of the welds which is changeable by weld heights With the results obtained in this study, a model ${\Delta}{\delta}/h^2=0.13553\;{N_{f}}^{-0.3151}$ for seam and raised edge welds having a given weld height is proposed to be useful for designers and inspectors.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.24 no.1
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• pp.41-46
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• 2016

This paper reviews and summarizes overall fatigue substantiation method of aircraft. The fatigue substantiation method has been studied using the related regulation and examples of industry application. And the comparisons of fatigue substantiation procedure between safe-life and damage tolerance design have been performed. Fatigue substantiation methods have wide variability depend on design methodology and type of aircraft such as fixed wing and rotorcraft. In this study, fatigue substantiation methodologies have been reviewed using analysis and test methods.

• Journal of Korean Public Health Nursing
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• v.24 no.2
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• pp.258-269
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• 2010

Purpose: This study investigated the effectiveness of AIDS education on knowledge, prejudice, susceptibility, severity, and intention of safe sex behavior among university students. Methods: This study was conducted from March, 2008 to May, 2008. The research design was a non-equivalent control group pre-post test. Participants 78 university students (control group) and 89 university students (experimental group). For the latter, AIDS education was provided once weekly for 1 h for 4 weeks. The educational program included understanding of sexuality, facts of AIDS, life stories of patients with AIDS, and safe sex behavior. The differences between two groups after education were analyzed by independent t-test. Results: The experimental group had significantly higher scores for knowledge, prejudice, susceptibility, and intention of safe sex behavior compared to the control group. However, no significant difference was found for severity between two groups. Conclusion: AIDS education can be effective in improving knowledge, prejudice, susceptibility, and intention of safe sex behavior, and is recommended as an effective AIDS education for university students.

• Safe Food
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• v.2 no.4
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• pp.23-28
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• 2007

• Safe Food
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• v.8 no.1
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• pp.12-17
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• 2013

• Safe Food
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• v.2 no.2
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• pp.51-57
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• 2007