• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1759-1761
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• 2004

In this paper, we studied on life-decision of underground cable of live-line state. Data of CV 6.6kV and 22kV cable's life is got data measured insulation resistance by D.C. overlapped current. We confirmed that D.C resistance reduced by time. Aging of cable could be occurred by electrical, thermal, mechanical stress and complex aging confirmed that proceeded by Weibull plot. In the result, life of 6.6kV cable remained 21 years till light caution and 35 years till heavy caution, so aging of 6.6kV XLPE cable was not occurred. Life of 22kV cable remained 10 years till light caution and 22 years till heavy caution. We confirmed that the designed life of 22kV cable is similar to the measured life.

• Animal Bioscience
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• v.34 no.4
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• pp.546-557
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• 2021

Objective: If fertilization does not occur within a specific period, the quality of unfertilized oocytes in the oviduct (in vivo aging) or in culture (in vitro aging) will deteriorate over time. Icariin (ICA), found in all species of Epimedium herbs, has strong antioxidant activity, and is thought to exert anti-aging effects in vitro. We asked whether ICA protects oocytes against age-related changes in vitro. Methods: We analyzed the reactive oxygen species (ROS) levels and expression of antioxidant, maternal, and estrogen receptor genes, and along with spindle morphology, and the developmental competence and quality of embryos in the presence and absence of ICA. Results: Treatment with 5 μM ICA (ICA-5) led to a significant reduction in ROS activity, but increased mRNA expression of glutathione and antioxidant genes (superoxide dismutase 1 [SOD1], SOD2, peroxiredoxin 5, and nuclear factor erythroid 2-like 2), during aging in vitro. In addition, ICA-5 prevented defects in spindle formation and chromosomal alignment, and increased mRNA expression of cytoplasmic maturation factor genes (bone morphogenetic protein 15, cyclin B1, MOS proto-oncogene, serine/threonine kinase, and growth differentiation factor-9). It also prevented apoptosis, increased mRNA expression of antiapoptotic genes (BCL2-like 1 and baculoviral IAP repeat-containing 5), and reduced mRNA expression of pro-apoptotic genes (BCL2 antagonist/killer 1 and activation of caspase-3). Although the maturation and cleavage rates were similar in all groups, the total cell number per blastocyst and the percentage of apoptotic cells at the blastocyst stage were higher and lower, respectively, in the control and ICA-5 groups than in the aging group. Conclusion: ICA protects oocytes against damage during aging in vitro; therefore, it can be used to improve assisted reproductive technologies.

• Structural Engineering and Mechanics
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• v.17 no.1
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• pp.29-50
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• 2004

A total life model was developed to assess the service life of aging aircraft. The primary focus of this paper is the development of crack growth life projection using the response surface method. Crack growth life projection is a necessary component of the total life model. The study showed that the number of load cycles N needed for a crack to propagate to a specified size can be linearly related to the geometric parameter, material, and stress level of the component considered when all the variables are transformed to logarithmic values. By the Central Limit theorem, the ln N was approximated by Gaussian distribution. This Gaussian model compared well with the histograms of the number of load cycles generated from simulated crack growth curves. The outcome of this study will aid engineers in designing their crack growth experiments to develop the stochastic crack growth models for service life assessments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.332-339
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• 2020

This study was a prior study to establish the shelf life of bulletproof helmets, considered the aging factor of bulletproof helmets. To estimate the aging factor of bulletproof helmets, we established a hypothesis that the 'temperature' factor would have the greatest impact on the shelf life of the bulletproof helmet, considering the environmental treatment of the American army's bulletproof helmet's materials. To verify the hypothesis, high temperature acceleration environmental treatment of bulletproof helmets was performed, and the Arrhenius formula was applied to calculate the shelf life. The study result confirmed the negative correlation between bulletproof performance and high temperature, and the influence of temperature as an aging factor was not significant by deriving life by using the Arrhenius model. The limitation of this study is that we couldn't obtain enough samples due to the specificity (miliary supplies) of the test subjects. However, given that the life-related research on bulletproof helmets has not been carried out, this research has great implications and could be used as a reference for improving the Korean Army's bulletproof helmet specifications.

• 한국노년학
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• v.36 no.4
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• pp.1075-1088
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• 2016

This study aimed to identify the effect of the active aging on life satisfaction and present an improvement strategies to increase life satisfaction in elderly people. Active aging is divide into three aspects; health, participation and security. The subjects were people older than 55 years who were enrolled in Korean Retirement and Income Study. The influencing effect was analyzed by a hierarchial regression. Key factors associated with active aging influencing life satisfaction were subjective health, mental health, participation in the labor market, income, and housing while subjective health was a determinant factor that best describes the effect of the active aging on life satisfaction. On the basis of above result, this study suggests that there needs to be an effort in improvement of physical and mental health, participation in the labor market, and housing at national and regional levels.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.27-34
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• 2021

This study is a descriptive research study to understand the effects of successful aging and SOC coping strategy on quality of life in middle-aged women. The study subjects were middle-aged women (40~65years old) across the country, and data were collected using a structured questionnaire. The collected data were analyzed by descriptive statistics, Independent t-test, one-way ANOVA, Pearson's correlation, and stepwise multiple regression using SPSS WIN/PC 24.0 statistics program. The study found that successful aging of middle-aged women, SOC alternative strategies and quality of life were statically correlated, and statistical significance was identified in order of successful aging(β=.41, p<.001) and SCO coping strategies(β=.17, p=.047) as variables describing quality of life. In this study, the explanatory power by the two variables was 24.7%. Therefore, in order to improve the quality of life of middle aged women, it is necessary to study and program programs to enhance the SOC coping strategy of successful aging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.119-122
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• 2000

Recently polymer insulators are being used for outdoor high voltage applications. Polymer insulators for transmission line have significant advantages over porcelain and glass insulators, especially for ultra-high voltage transmission lines. Their advantages are light weight, vandalism resistance and hydrophobicity. Polymer insulators are a relatively new technology, but their expected life is still unknown. Therefore these estimating technique are very important. Their life time is related to weathering and operating condition. Multi-aging test is requested because aging factor is occurred by multi-aging than unique aging. The aging test about polymer insulators have mainly carried out by IEC 61109. This paper presents multi-stress chamber experiments and tracking wheel test to examine the tracking and erosion performance of polymer insulator for transmission. Multi-stress testing is able to demonstrate deficiencies of polymer insulator materials and designs, including the nature of interfaces in insulation design. We have investigated IEC 61109 Annex C (5000h aging test) and CEA tracking wheel test as test methods of artificial accelerated aging. The aging degree of polymer insulator is estimated by leakage current, measurement of hydrophobicity degree, damage conditions of insulator surface, withstand voltage test etc.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.199-211
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• 2021

This study suggests an alternative for solving quality-of-life problems of an aging workforce by seeking ways to utilize an aging workforce in corporations and society. This research empirically analyzed data from the 6th panel data of aging. Study results are as follows. First, it was confirmed that job satisfaction of aging manpower plays a mediating role in the relationship between quality of life and the job characteristics of an aging workforce. Second, it was found that the wage level of regular workers had a significant effect on job satisfaction and quality of life, and the job satisfaction of regular workers was mediated between wage level and quality of life. On the other hand, the wage level of non-regular workers did not have any effect on job satisfaction and quality of life. The results of this study suggest the necessity for companies to recognize the use of an aging workforce to improve social value. Furthermore, our results provide implications for domestic firms and government policymakers on how to use a domestic aging workforce and how to utilize regular and non-regular workers.

• 한국노년학
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• v.41 no.1
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• pp.1-24
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• 2021

This study aims to examine how old people think about 'dignifiable aging'. For the study, the authors have tried to understand and analyze of old people's view on 'classy and gracious aging' through their life experiences. The study focuses on the questions of 'how the participants experience aging', 'how they understand well, classy and successful aging and 'how they explain their ideas of the aging, then analyzes their ideas as types of 'within cases' as well as 'inter cases'. Indepth interview has employed as main methodology of data collection with the analysis of concerned written documents such as on-line and off-line essays as secondary data. The collected data had been basically sorted and analyzed by sorting commonimity and differences. Then they have been classified into the thems that indicate meanings and forms of 'dignified aging': 'ageless mind', 'happiness determined by one's mind', 'responsibility on family', 'desire for learning and social activities'. These meaning-units are added up to the main meaning of '(fullfilled) satisfaction through life-values' mediated by 'acceptance and acknowledgement', 'efforts', 'others' gaze', 'dreams and hopes', '(fullfilled) Satisfaction through life-values' can be achieved by 'sharing with others'. An interesting fact is that the meaning-units can be devided into two groups: 'the real life is the ideal life' which explains the actualization of the ideal in the daily life and 'life, conflict, the ideal' in which the real and the ideal are parellel with constant conflicts. In the conclusion, some implications and suggestions derived from the analysis are described from the v iew of social welfare.

• 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.