• Particle and aerosol research
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• v.5 no.2
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• pp.45-52
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• 2009

Black carbon, which is a by-product of combustion of fossil fuel and biomass burning, is the component that imposes the largest uncertainty on quantifying aerosol climate effect. The direct, indirect and semi-direct climate effects of black carbon depend on its state of the mixing with other water-soluble aerosol components. The process that transforms hydrophobic externally mixed black carbon particles into hygroscopic internally mixed ones is called "aging". In most climate models, simple parameterizations for the aging time scale are used instead of solving detailed dynamics equations on the aging process due to the computation cost. In this study, a new parameterization for the black carbon aging time scale due to condensation and coagulation is presented as a function of the concentration of hygroscopic atmospheric components and the black carbon particle size. It is shown that the black carbon aging time scale due to condensation of sulfuric acid vapors varies to a large extent depending on the sulfuric acid concentration and the black carbon particle size. This result indicates that the constant aging time scale values suggested in the literature cannot be directly applied to a global scale modeling. The aging time scale due to coagulation with internally mixed aerosol particles shows an even stronger dependency on particle size, which implies that the use of a particle-size-independent aging time scale may lead to a large error when the aging is dominated by coagulation.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.710-713
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• 2003

The wall charge is major factor to determine the discharge characteristics. The minimum sustain voltage related to the wall charge decay were investigated as a function of aging time in AC plasma display panel. For the long time scale, the wall charge decay time is dependent on the aging time. The inverse time scale of the wall charge decay has the maximum value at around 3 hours aging time and then fell down.

• Journal of Communications and Networks
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• v.15 no.4
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• pp.338-351
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• 2013

Multiple-input multiple-output (MIMO) communication may provide high spectral efficiency through the deployment of a very large number of antenna elements at the base stations. The gains from massive MIMO communication come from the use of multi-user MIMO on the uplink and downlink, but with a large excess of antennas at the base station compared to the number of served users. Initial work on massive MIMO did not fully address several practical issues associated with its deployment. This paper considers the impact of channel aging on the performance of massive MIMO systems. The effects of channel variation are characterized as a function of different system parameters assuming a simple model for the channel time variations at the transmitter. Channel prediction is proposed to overcome channel aging effects. The analytical results on aging show how capacity is lost due to time variation in the channel. Numerical results in a multicell network show that massive MIMO works even with some channel variation and that channel prediction could partially overcome channel aging effects.

• Korean Journal of Social Welfare
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• v.64 no.1
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• pp.101-124
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• 2012

This study examined the longitudinal changes of self-perceptions of own aging among middle-aged and elderly adults, using the latent growth modeling with the three waves of the "Aging and the Quality of Life of the Elderly in Korea", which sampled adults aged over 45 living in Seoul and Chuncheon. The dependent variable is attitudes toward own aging, the sub-scale of the Philadelphia Geriatric Center Morale Scale developed by Lawton (1975). The results showed that the research participants' attitudes of their own aging deteriorated over time. In addition, the lower initial status of the research participants' attitudes of their own aging was associated with being older, being non-married, living in rural areas, attaining the lower level of education, having the fewer social activities, reporting the worse subjective economic status, and reporting the worse subjective health status. The slope of the research participants' attitudes of their own aging differed by the residence areas, educational attainments, subjective economic status and subjective health status. In particular, the difference of the initial status by educational attainments grew over time. Social welfare policy and practice implications are discussed for middle-aged and elderly adults to improve attitudes toward their own aging.

• Journal of Korea Foundry Society
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• v.30 no.4
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• pp.142-146
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• 2010

To elucidate the characteristics of cavitation erosion of super duplex stainless steel, a cavitation erosion test, an optical microstructure, a hardness test, and a transmission electron microscope (TEM) analysis were conducted. As aging time at $475^{\circ}C$ increased, the hardness of ferrite phase increased whereas that of austenite phase was nearly constant. The reason why the cavitation erosion resistance increased with an increase of aging time was due to the formation of W-rich phases (${\alpha}$') of a nanometer scale with the high hardness that were precipitated within ${\alpha}$-grains and at ${\alpha}$-grain boundaries during aging, compared with that of the solution annealed alloy.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.1
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• pp.23-30
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• 1993

Hydrogenation on the top gate and bottom gate Poly-Si TET's was performed by using Nh$_{3}$ plasma and annealing SiN film deposited by PECVD and then the electric characteristics on Poly-Si TET were investigated. As the time of NA$_{3}$ plasma treatment increaes, on/off current ratio gradually increases and the swing value decreases. The trap densities of graim boundaries in Poly-Si decrease very much during the inital 20min of hydrogenation time, and the decreasing scale becomes smaller after 20 min. The electric characteristics of the top gate TFT are better than those of the bottom gate TFT, it is considered due to the defects at the interface between the Poly-Si and the underlayer, SiO$_{2}$. After NH$_{3}$ plasma was treated for 2 hours for the top gate TFT, as the aging time atroon temperature increases on current was not scacely changed and off current decreases more than 1 order. Gate current density recovers to original value after the aging treatment for 8 days and then the electric characteristics are finally improved. It is suggested that the degraded characteristics of gate oxide are improved, from the variations of C-V characteristics with aging time. For the hydrogenation of isothermal and isochronal annealing SiN film deposited by PECVD, the characteristics of Poly-Si TFT are improved with increasing annealing temperature and are not largely changed with increasing annealing time. This results is good in agreement with the hydrogen reduction in Sin film as variations of annealing temperature and time.

• Journal of Korea Entertainment Industry Association
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• v.14 no.6
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• pp.251-258
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• 2020

This study was conducted to find out the difference between aging anxiety and self-efficacy according to the general characteristics of the elderly in the community and to find out the correlation between aging anxiety and self-efficacy. From April 2019 to August 2019, 284 responses were used in the final analysis, focusing on senior citizens' health centers, welfare centers for senior citizens, health centers, and senior citizen centers in Gwangju and South Jeolla Province, and the survey was conducted using an aging anxiety scale and a self-efficacy scale. Studies have shown that aging anxiety has shown statistically significant differences in age, economic level, health condition, and present concern, and self-efficacy has shown statistically significant differences in age, academic background, religion, economic level and health status. The higher the age anxiety, the lower the self-efficacy. It is thought that it can be used to establish specific strategic measures for successful aging that can keep healthy for a long time and maintain a safe life.

• Journal of Marine Bioscience and Biotechnology
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• v.12 no.1
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• pp.66-74
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• 2020

Marine algae contain a variety of substances, such as mycosporine-like amino acids, which can defend against UV irradiation. Among them, Porphyra-334 derived from Porphyra yezoensis is attracting attention as a novel active ingredient for anti-aging cosmetics because of its excellent anti-oxidative, anti-inflammatory, and wound-healing properties through promoting skin cell migration. In this study, a process using direct current (DC) for increasing the yield of large-scale purification of Porphyra-334 was developed. When DC was applied to obtain Porphyra-334 efficiently, the purification time was shortened by approximately 1/4 compared with the process wherein DC was not applied; moreover, the yield of purification was improved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.481-484
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• 2003

Recently polymer insulators are being used for outdoor high voltage applications. Polymer insulators have significant advantages over porcelain and glass insulators. With the gradual improvement of their design and material, their reliability has also increased. It is however difficult to establish how they will perform after several years of service. Aging of the insulator weathershed may lead to damages such as excessive chalking and crazing, erosion and tracking which affect the insulator performance. In service insulator are subjected to aging stresses such as humidity, pollution and electrical field which act singly or in combination. There have been numerous accelerated laboratory tests developed with the intention of evaluating suitability of polymeric materials. Some of these are strictly material tests, where as, others evaluate full scale devices. Service experience plays a key role in the utility selection of polymer insulator, but is time consuming, and may not always be available. Hence there is a need for a meaningful and reliable accelerated aging test for polymer insulator. This paper describes multi-stress aging test for reliability of polymer insulator This paper presents the rule of multi-stress aging test and test chamber for polymer insulator in korea electrotechnology research institute.

• Journal of the Korean Geographical Society
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• v.47 no.3
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• pp.359-374
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• 2012

This paper intends to examine spatial patterns and regional variations of aging population in Korea based on census data for 163 areas during 1980~2010. It briefly investigates general characteristics of aging population in Korea from previous studies and clarifies spatial patterns of aging process at regional level with reference of population growth rate at different time periods. Cities in Korea are classified into several stages including aging society, aged society and super-aged society according to the percentages of aging population out of total population every five years. At the regional scale, the stage of aging society was revealed from 1980, while the stage of aged society was shown from 1995 and super-aged society was entered from 2000 in Korea. Eighty cities in the analysis were shown at the stage of super-aged society in 2010. The portions of aging population are highly related to city size and population growth rate. For instance, the cities both in small size and with low population growth rate are revealing high percentage of aging population. As of 2010, most rural areas are staged into super-aged society, while most cities within Seoul metropolitan area and mid-sized cities are kept in the stage of aging society. At regional scale, there are no significant statistical correlations between total fertility rate and aging population.