• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.175-178
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• 2003

Tool life in cold forging is influenced by tool quality as well as forging conditions and quality of forging material. This paper presents some typical examples of tool life improvement in aspect of tool quality depending on tool design and tool manufacturing parameters. For the purpose of improving tool life, suggestions should be based on accurate understanding of tool operating conditions in cold forging process. FE simulation known as CAE is effective in order to make clear the conditions by some numerically calculated result.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.91-99
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• 1998

A correlation between the low-cycle fatigue life and the scuffing-failure life is demonstrated using the plastic strain in boundary lubricated sliding. Loadings proportional to hardness with three different lubricated conditions were used to evaluate the plastic strain. As the results of scuffing tests using vacuum pump oils in nitrogen gas, plastic strain shows 0.0062, and In the mineral oils and commercial engine oils in air, plastic strain show 0.0042 and 0.00092. Those are very useful to describe quantitatively the real lubricated sliding conditions, and are very effective to find the relation between the low-cycle fatigue life and the scuffing life.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.804-811
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• 2010

The fatigue crack propagation is stochastic in nature, because the variables affecting the fatigue behavior are random and have uncertainty. Therefore, the fatigue life prediction is critical for the design and the maintenance of many structural components. In this study, fatigue experiments are conducted on the specimens of magnesium alloy AZ31 under various conditions such as thickness of specimen, the load ratio and the loading condition. The probability distribution fit to the fatigue failure life are investigated through a probability plot paper by these conditions. The probabilities of failure at various conditions are also estimated. The fatigue design life is predicted by using the Weibull distribution.

• The Korean Society of Law and Medicine
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• v.11 no.1
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• pp.297-329
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• 2010

The bioethics as a comprehensive and normative control method of life sciences including the technology of advanced medical care, on the one hand, it has modified the conditions for allowing the progress of life sciences. On the other hand, it has put the brakes on attempts of life sciences violating the dignity and value of human beings, natural order. Positively, bioethics presents ethical bases, suggests organization of the legal and institutional conditions, and enables elimination of the legal and institutional obstacles, for the progress of life sciences. Negatively, it has presented justifiable prospects and road maps of life sciences, not to take indiscreet and intemperate turn of violating the dignity and value of human beings, natural order, and its such roles must be carried on.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.67-70
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• 2000

The tool life is not long enough under sever forming condition in warm forging. The tool life is affected by wear heat fatigue plastic deformation and so on. Especially wear is one of the most serious factors for tool life. To increase tool life we should consider various factors like processing design die design die materials lubrication and cooling system This study design to obtain the steady state temperature of die by FEM analysis under several conditions of cooling. There are four cooling conditions in this study no cooling internal cooling external cooling and both internal and external cooling. With above obtained temperatures tool life is predicted using Archard's model that is considered softening of die. The effect of internal cooling system is better than that of externally cooled die. To predict the die life the steady state temperature is calculated by using mean temperature of die. Considering only wear the die life much longer as the cooling effect is bigger. The more accurate die life will be predicted if we consider heat crack as well as wear.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.2
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• pp.43-53
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• 2024

This study attempted to elucidate the ecological niches and influencing environmental factors of Quercus variabilis and Quercus acutissima, which are representative deciduous broad-leaved trees in Korean forests, taxonomically close and genetically similar, under climate change conditions. Under climate change conditions induced by increased CO₂ and temperature, soil moisture and nutrient environments were manipulated in four gradients. At the end of the growing, plants were harvested to measure growth responses, calculate ecological niches, and compare them with those of the control. Eperimental plants were grown for 180 days in a glass greenhouse designed with four gradients each for soil moisture and nutrient environments under climate change conditions induced by increased CO₂ and temperature. After harvesting, growth responses of leaf traits were measured, ecological niches were calculated, and these were compared with those of the control groups. Furthermore, the responses of the two species' populations were interpreted using principal component analysis(PCA) based on leaf trait measurements. As a result, under climate change conditions, the ecological niche breadth for moisture environment was broader for Quercus variabilis than Quercus acutissima, whereas for the nutrient environment, Quercus acutissima exhibited a broader niche breadth than Quercus variabilis. And the rate of change in ecological niche breadth due to climate change decreased for Quercus variabilis in both moisture and nutrient environments, while for Quercus acutissima, it increased in the moisture environment but decreased in the nutrient environment. Additionally, in terms of group responses, both Quercus variabilis and Quercus acutissima expanded their ecological niches under climate change conditions in both soil moisture and nutrient conditions, with Quercus acutissima exhibiting a broader niche than Quercus variabilis under nutrient conditions. These results indicate that the changes in leaf morphological characteristics and the responses of individuals reflecting them vary not only under climate change conditions but also depending on environmental factors.

• Journal of the Korean Data and Information Science Society
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• v.15 no.4
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• pp.935-943
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• 2004

Most of the accelerated life tests deal with tests that use only one accelerating variable and no other explanatory variables. Frequently, however, there is a test to use more than one accelerating or other experimental variables, such as, for examples, a test of capacitors at higher than usual conditions of temperature and voltage, a test of circuit boards at higher than usual conditions of temperature, humidity and voltage. A accelerated life test is extended to M-level stress accelerated life test with k-stress variables. The optimal design for Weibull distribution is studied with k-stress variables.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1391-1393
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• 2008

In this paper, the long-term reliability for 1.25G transceiver in use of high speed optical access network is investigated. High temperature storage tests and accelerated life tests are used to long-term reliability. Accelerated aging test have been during 3,000 hour of the three accelerated aging conditions by caused high temperature stress. Mean life is assumed to follow the Arrhenius relationship and analysis from the failure data obtained in the accelerated aging conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.646-662
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• 2016

This study of elderly couples examined the main environmental factors affecting the married life satisfaction and life satisfaction of the spouses. The survey was conducted on 60-year-old elderly couples who live in the metropolitan area of Seoul and Gyeonggi. A total of 400 questionnaires were used to analyze the exception of a number of 12 388 additional missing data. The results were as follows. First, environmental factors affecting the marital satisfaction of spouses' personality suitability and gender role attitudes appeared in the economic conditions. Second, the spouses environmental factors affecting the life satisfaction turned out to be the gender role attitude, reliability and economic conditions. Third, the major environmental factors affecting both spouses married life satisfaction and life satisfaction was found to be the gender role attitude and economic conditions. Fourth, the environmental factors representing a moderating effect on the supporting spouse between environmental factors and life satisfaction appeared to be the personality suitability and economic conditions. These results suggest that the recent increases in the twilight divorce rate may be due to the marriage satisfaction and common factors of gender role attitudes. Therefore, to improve the lives and economic conditions as well as the satisfaction of the spouse, the support of important factors are needed to adjust the crisis of old age couples. Therefore, a relevant policy that targets elderly couples through counseling and education will be needed.

• Journal of Family Resource Management and Policy Review
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• v.5 no.1
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• pp.1-13
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• 2001

The purpose of this study was not only to identify real-life conditions of Korean-Chinese in Korea(clothing habits, eating habits, housing habits, economic life and leisure activities) but also to reveal the related variables that shall affect life quality. The subjects were selected from Korean-Chinese in Korea related to ‘Compatriots House’. The survey was conducted from June 20th to July 5th, 2000. A total of 225 questionnaires out of 350 were used as the final data analysis. All data were analyzed using the SAS/PC for frequency, percentage, F-test and Regression analysis. The study revealed the following results. 1. Significant differences were found in life quality of Korean-Chinese in Korea according to age(p<.05), optimum income (p<.001), health condition(p<.001), education level(p<.005), and entry motivation(p<.05). 2. Variable such as optimum income(β=.334) education level(β=-.190), monthly income(β=.170), health condition(β=.151), and self-esteem(β=.133) affected life quality of Korean-Chinese in Korea. Korean-Chinese’s life quality was explained by these variable(35%). The optimum income variable was the primary influential factor.