• 한국입자에어로졸학회지
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• 제5권2호
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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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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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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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• 제15권4호
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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.

• 한국사회복지학
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• 제64권1호
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• pp.101-124
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• 2012

본 연구에서는 중노년층의 본인의 노화에 대한 태도에 관한 종단적 변화와 이에 영향을 미치는 요인을 알아보기 위해 "고령화와 한국노인의 삶의 질에 관한 연구"의 3개년도 자료를 잠재성장모델로 분석하였다. 분석결과, 중노년층의 본인의 노화에 대한 태도는 시간이 지남에 따라 부정적으로 변화하는 것으로 나타났다. 또한 고연령집단일수록, 무배우일수록, 농촌지역 거주자일수록, 교육수준이 낮을수록, 사회활동의 수가 적을수록, 주관적 경제상태에 여유가 없을수록, 주관적 건강상태가 나쁠수록 중노년층의 본인의 노화에 대한 초기 태도는 부정적인 것으로 나타났다. 중노년층의 본인의 노화에 대한 태도의 종단적 변화는 거주지역, 교육수학기간, 주관적 경제상태, 주관적 건강상태에 따라 다른 것으로 나타났다. 연구결과를 토대로 중노년층이 본인의 노화에 대한 부정적인 태도를 줄이기 위해 필요한 정책적, 실천적 시사점에 대해 논의하였다.

• 한국주조공학회지
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• 제30권4호
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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.

• 전자공학회논문지A
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• 제30A권1호
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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.

• 한국엔터테인먼트산업학회논문지
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• 제14권6호
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• pp.251-258
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• 2020

본 연구는 지역사회 노인의 일반적 특성에 따른 노화불안과 자기효능감의 차이를 알아보고 노화불안과 자기효능감 간의 상관관계를 알아보고자 실시하였다. 2019년 4월부터 2019년 8월까지 광주·전남지역 노인건강센터, 노인복지관, 보건소, 경로당을 중심으로 284명의 응답 자료를 최종 분석에 사용하였으며, 노화불안 척도와 자기효능감 척도를 사용하여 설문 조사를 실시하였다. 연구결과 노화불안은 연령, 경제적 수준, 건강상태, 현재걱정에서 통계적으로 유의한 차이가 나타났으며, 자기효능감은 연령, 학력, 종교, 경제적 수준, 건강상태에서 통계적으로 유의한 차이가 나타났다. 노화불안이 높을수록 자기효능감은 낮게 나타났다. 건강을 오래 지켜나가고 안전할 생활을 유지할 수 있는 성공적인 노화를 위한 구체적인 전략 방안 수립에 활용할 수 있을 것으로 생각된다.

• 한국해양바이오학회지
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• 제12권1호
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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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.

• 대한지리학회지
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• 제47권3호
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• pp.359-374
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• 2012

본 논문은 인구센서스 자료를 이용하여 1980년부터 2010년까지의 163개 시군구 지역을 대상으로 한국 인구고령화의 지역적 전개 양상을 분석한 것이다. 이를 위해 고령인구의 일반적인 특징을 기존연구를 중심으로 정리하고, 고령인구의 분포 변화를 시계열적으로 파악하였으며 인구성장률 등과 관련하여 고령인구의 분포를 해석하였다. 1980년부터 5년 단위로 고령인구의 비율에 따라서 한국의 163개 지역들을 고령화사회, 고령사회, 초고령사회로 구분하였다. 지역적 차원에서 시기별로 고령인구의 추이를 고찰하면 1980년부터 고령화사회에 진입하였고, 1995년에 고령사회, 2000년에는 초고령사회에 진입하여 2010년에는 80개의 지역이 초고령사회에 진입하였다. 고령인구의 비율은 도시규모와 인구증가율과 깊은 관계를 보인다. 즉, 도시의 규모가 작을수록 고령인구비율이 높았고, 인구증가폭이 낮을수록 고령인구의 비율은 높은 경향을 나타내었다. 2010년 기준으로 수도권 대도시와 중소도시의 경우 고령화사회에 진입한 도시가 대부분인 반면 농어촌지역의 대부분은 초고령사회에 진입하였다. 지역수준에서 합계출산율과 고령인구는 관련성이 없는 것으로 파악되었다.