• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.462-469
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• 2010

Gas-liquid 2 phase processes are usually used in chemical, biochemical, environmental engineering and food process. For optimizing these processes, understanding bubble's precise movement and shape are needed. Bubble's movement and shape are effected by liquid's properties-viscosity, surface tension and bubble's properties-size, velocity. This paper deals with experimental data of bubble's movement and shape in high viscous silicone oil. Also, drag coefficient and deformation factor given by other researcher's papers and books are used to predicting and comparing bubble's terminal velocity, drag coefficient, deformation factor and shape with experimental value. Experimental data show that bubble moves faster when it moves in lower viscous silicone oil and it's drag coefficient is bigger when it moves in high viscous silicone oil. Bubble's shape is close to sphere when moving in high viscous silicone. Formulas proposed by Batchelor expect most accurate prediction for bubble's velocity and drag coefficient. Bubble's 2D shape predicted by Batchelor's energy balance, drag coefficient and deformation factor show excellent agreement with experimental bubble's 2D shape.

• The Korean Journal of Applied Statistics
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• v.28 no.4
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• pp.603-620
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• 2015

The National Pension of Korea is a public social security system designed to alleviate social risks and poverty that has had a major impact on the quality of life for the aging population. However, a rapidly aging population and low fertility threaten the sustainability of national pension in Korea. The National Pension Research Institute publishes a nancial projection every ve years; consequently, the government has lowered the entitlements for the sustainability of national pension based on the projection results. The current reform of the pension system that arbitrarily reduces the entitlements might detract from the income security role of the national pension for pensioners without accounting for the highest elderly poverty rate in the OECD countries. We first discuss methods for the financial projection of the national pension in terms of population, subscribers, and pensioner projections in order to estimate the pension reserve fund and the financial depletion year. We also conduct a sensitivity analysis for population variables, institutional variables, and economic variables based on pension reserves and the financial depletion year. We evaluate intergenerational fairness between the income hierarchy by conducting a money's worth analysis. Finally, we investigate the possibility of the sustainability of national pension by adjusting pension contributions and entitlements (income replacement rate). A new dependency ratio shows that a simple reform of the national pension does not secure the sustainability of the national pension without adapting a pay-as-you-go system.

• Journal of the Korean Data and Information Science Society
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• v.28 no.3
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• pp.525-532
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• 2017

Recently, there shows a trend in Korea that the rate of the population entering into aging is the most rapidly increasing among the OECD countries. Consequently, This study, therefore, aims at analyzing the forms of portfolio establishment by group, the factors affecting the old age preparation, and the presence of middle-aged households' preparation for the old ages in order to forestall social problems like the poverty ration of elderly that have been caused by the rapidly aging society. The result shows that the portfolio for the old age preparation can be expanded if a combination product of finance and real estate is developed as a means of old age preparation. Upon the results of the study above, it can be seen that the old age preparations differ according to not only the demographic elements, but also the extent to how much resources one holds. Especially, the various factors affecting the holding resources vary householder by household depending on whether they prepare for the old ages or not.

• Journal of the Korean Data and Information Science Society
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• v.26 no.6
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• pp.1199-1206
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• 2015

into aging is the most rapidly increasing among the OECD countries. Consequently, this study aims at analyzing the forms of portfolio establishment by group, the factors affecting the old age preparation, and the presence of middle-aged households' preparation for the old ages in order to forestall social problems like the poverty ration of elderly that have been caused by the rapidly aging society. The result shows that the portfolio for the old age preparation can be expanded if a combination product of finance and real estate is developed as a means of old age preparation. Upon the results of the study above, it can be seen that the old age preparations differ according to not only the demographic elements, but also the extent to how much resources one holds. Especially, the various factors affecting the holding resources vary householder by household depending on whether they prepare for the old ages or not.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.830-836
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• 2006

In this paper described an auto tuning neuro-fuzzy PID controller based neural network. The PID type controller has been widely used in industrial application due to its simply control structure, easy of design, and inexpensive cost. However, control performance of the PID type controller suffers greatly from high uncertainty and nonlinearity of the system, large disturbances and so on. In this paper will design to take advantage of neural network fuzzy theory and pid controller auto toning technique. The value of initial scaling factors of the proposed controller were determined on the basis of the conventional PID controller parameters tuning methods and then they were adjusted by using neural network control techniques. This controller simple structure and computational complexity are less, and also application is easy and performance is excellent in system that is strong and has nonlinearity to system dynamic behaviour change or disturbance. Finally, the proposed auto tuning neuro-fuzzy controller is applied to magnetic levitation. Simulation results demonstrated that the control performance of the proposed controller is better than that of the conventional controller.

• Korea journal of population studies
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• v.24 no.1
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• pp.149-182
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• 2001

Due to the sustained increase in lifts expectancy, the number and proportion of the aged population has substantially increased, the proportion of the total population aged 65 and over was 7.1% in 2000 and 14.3% in 2022. But All public pension schemes in Korea, including the National Pension scheme, civil servants pension scheme, private school teachers pension scheme and the military pension scheme, are facing valving degree of financial problems at present because of their weak and unstable financial bases. with the result that some of them have recorded deficits for some time and the others are expected to run deficits in the near future. This crisis in financial sustainability in public pension schemes is attributable to the structural weakness of the schemes which can be characterized as high benefits, low contribution. Therefore, this article focuses on alternative of public pension schemes reform in Korea. The results is as follows. First, a basic pension is proposed to be newly established and the earnings related portion of National Pension Scheme will be as national pension. Secondly, the Basic Pension is a universal basic pension covering all nationals over 18 years and older, thereby achieving \"one pension for everybody\" Thirdly, National Pension will be operated as an earnings related pension covering only those participants with assessed income. Fourth1y, the current participants of public occupational pensions will also join the Basic Pension as well as the public occupational pensions whose scope of works will be reduced. And finally, The conversion of Retirement Allocation Scheme into a corporate pension should be left to the discretion of the company concerned.

• The Journal of the Korea Contents Association
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• v.19 no.8
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• pp.525-534
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• 2019

Korea is facing one of the fastest aging population problems in the world due to the extension of life expectancy and low birth rates due to economic development and the development of health care. It has become difficult to take care of elderly people in need of long-term care at home, and social problems such as dementia and the increase in stroke cases are serious problems. The government is enacting and implementing the Long-Term Care Insurance Act for the purpose of improving the quality of life for senior citizens subject to long-term care and alleviating the burden of family support in order to solve such social structure and problems for senior citizens. However, as a result of the implementation of the long-term care insurance system for the elderly, the privatization of the facilities and the disorder are causing widespread requests for public accountability of the services and the enhancement of the quality of the facilities. In addition, various arrangements are needed for the production of low-wage medical care workers, tasks for quality improvement, problems regarding financing methods, and so on. In order to maintain and develop the long-term care insurance system for the elderly, the government will consider seeking ways to improve the legal and institutional aspects according to changes in the social environment of the age, as well as seeking mental and psychological measures for the stabilization of old life as well as physical health.