• 한국재료학회지
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• 제32권1호
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• pp.51-55
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• 2022

Generally, Au electrodes are the preferred top metal electrodes in most perovskite solar cells (PSCs) because of their appropriate work function for hole transportation and their resistance to metal-halide formation. However, for the commercialization of PSCs, the development of alternative metal electrodes for Au is essential to decrease their fabrication cost. Ag electrodes are considered one of the most suitable alternatives for Au electrodes because they are relatively cheaper and can provide the necessary stability for oxidation. However, Ag electrodes require an aging-induced recovery process and react with halides from perovskite layers. Herein, we propose a bilayer Au/Ag electrode to overcome the limitations of single Au and Ag metal electrodes. The performance of PSCs based on bilayer electrodes is comparable to that of PSCs with Au electrodes. Furthermore, by using the bilayer electrode, we can eliminate the aging process, normally an essential process for Ag electrodes. This study not only demonstrates an effective method to substitute for expensive Au electrodes but also provides a possibility to overcome the limitations of Ag electrodes.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1114-1123
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• 2015

Bushing is the key link to connect outer and inner insulating systems and also the essential electric accessory in electric power system, especially in the high voltage engineering (AC 1000kV, DC 800kV). This paper presented the experimental research of thermal aging characteristic of oil-paper insulation used in bushing. A thermally accelerated aging experiment at 90℃ was performed. The bushing models containing five layers of paper were sealed into the aging vessels and further aged for 250 days. Then several important parameters associated with the aging were observed and evaluated. The results showed that the degree of polymerization (DP) of papers gradually decreased. The DP values of outermost layer and middle layer fit well into the second-order kinematic model and first-order kinematic model, respectively. Less deterioration speed of the inter-layer paper than outer layer was confirmed by the variation of DP. Hydrolysis was considered as the main cause to this phenomenon. In addition, the logarithm of the furfural concentrations in insulation oil was found to have good linear relationship with DP of papers. Interestingly, when the aging time is about 250 days and DP is 419, the aging process reaches an inflection point at which the DP approaches the leveling off degree of polymerization (LODP) value. Both tanδ and acid number of oils increased, while surface and volume resistivity of papers decreased. The obtained results demonstrated that thermal aging and moisture absorbed in papers brought great influence to the degradation of insulating paper, leading to rapid decrease of DP and increase of the tanδ. Thus, the bushing should be avoided from damp and real-time monitoring to the variation of tanδ and DP values of paper is an effective way to evaluate the insulation status of bushing.

• 대한토목학회논문집
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• 제33권3호
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• pp.855-864
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• 2013

지진격리장치로서 천연고무받침의 동적 특성은 주재료인 고무의 동적거동과 비선형 성질에 의존하고 있다. 역학적이나 환경적인 영향으로 인해 고무재료에 노화가 진행되고 결국에는 손상이 불가피하게 발생하게 된다. 고무재료의 노화에 주원인은 높은 온도에서 반응열로 인한 산화반응으로 알려져다. 이에 따라 천연고무받침에 대한 가속 열 노화실험을 수행하여 열 노화 전 후에 대해 받침의 특성값을 상호 비교하였다. 실험 결과 열 노화 현상은 전단강성과 에너지 감쇠 그리고 등가감소계수에 영향이 있음을 알 수 있었다. 또한 열 노화에 의한 동적특성의 저하를 실제 교량에 적용하여 천연고무받침의 열 노화가 교량의 내진성능에 미치는 영향을 수치해석을 통해 비교분석하였다. 그 결과 천연고무받침에 대하여 열 노화에 따른 기본 특성변화가 교량의 내진성능에 미치는 영향은 크지 않음을 알 수 있었다.

• The Korean Journal of Physiology and Pharmacology
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• 제22권5호
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• pp.467-479
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• 2018

The aging process induces a plethora of changes in the body including alterations in hormonal regulation and metabolism in various organs including the heart. Aging is associated with marked increase in the vulnerability of the heart to ischemia-reperfusion injury. Furthermore, it significantly hampers the development of adaptive response to various forms of conditioning stimuli (pre/post/remote conditioning). Aging significantly impairs the activation of signaling pathways that mediate preconditioning-induced cardioprotection. It possibly impairs the uptake and release of adenosine, decreases the number of adenosine transporter sites and down-regulates the transcription of adenosine receptors in the myocardium to attenuate adenosine-mediated cardioprotection. Furthermore, aging decreases the expression of peroxisome proliferator-activated receptor gamma co-activator 1-alpha ($PGC-1{\alpha}$) and subsequent transcription of catalase enzyme which subsequently increases the oxidative stress and decreases the responsiveness to preconditioning stimuli in the senescent diabetic hearts. In addition, in the aged rat hearts, the conditioning stimulus fails to phosphorylate Akt kinase that is required for mediating cardioprotective signaling in the heart. Moreover, aging increases the concentration of $Na^+$ and $K^+$, connexin expression and caveolin abundance in the myocardium and increases the susceptibility to ischemia-reperfusion injury. In addition, aging also reduces the responsiveness to conditioning stimuli possibly due to reduced kinase signaling and reduced STAT-3 phosphorylation. However, aging is associated with an increase in MKP-1 phosphorylation, which dephosphorylates (deactivates) mitogen activated protein kinase that is involved in cardioprotective signaling. The present review describes aging as one of the major confounding factors in attenuating remote ischemic preconditioning-induced cardioprotection along with the possible mechanisms.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.1112-1113
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• 2005

• 산업융합연구
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• 제18권1호
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• pp.87-96
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• 2020

본 연구는 노인의 신체이미지가 성공적 노화에 미치는 영향에서 성장 마인드셋과 희망의 이중 매개효과를 검증하는데 목적이 있다. 이를 위해 충청남도 D시, S시 및 D광역시의 노인 422명을 대상으로 설문조사하였고 수집한 자료는 SPSS 25.0과 PROCESS macro 3.4 프로그램을 활용하여, 빈도 분석, 신뢰도 분석, 상관 분석 및 부트스트랩을 통한 이중 매개 분석을 수행하였다. 연구의 결과는 다음과 같다. 첫째, 상관분석 결과 각 변인들 간에는 통계적으로 유의미한 정적 상관관계가 있었다. 둘째, 경로분석 결과 신체이미지는 성장 마인드셋과 희망에 정적 영향을 미쳤고, 성장 마인드셋은 희망과 성공적 노화에 정적인 영향을 주었으며, 희망 또한 성공적 노화에 유의미한 영향을 미쳤다. 셋째, 이중 매개효과 분석 결과 신체이미지와 성공적 노화의 관계에서 성장 마인드셋과 희망은 이중 매개하였다. 본 연구는 노인들의 성공적인 노화를 위한 신체이미지, 성장 마인드셋 및 희망을 활용한 새로운 모델과 기초자료를 제공하였다.

• 전기학회논문지
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• 제59권4호
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• pp.693-699
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• 2010

General transformer's life is known as paper insulation' life. If a transformer is degraded by these aging factors, it is known that electrical, mechanical and chemical characteristics for transformer's oil-paper are changed. When the kraft paper is aged, the cellulose polymer chains break down into shorter lengths. It causes decrease in both tensile strength and degree of polymerization of paper insulation. The paper breakdown is accompanied by an increase in the content of furanic compounds within the dielectric liquid. In this paper it is aimed at analysis on correlation between aging characteristics for insulating diagnosis of thermally aged paper. For investigating the accelerated aging process of oil-paper samples accelerating aging cell was manufactured for estimating variation of paper insulation during 500 hours at $140^{\circ}C$ temperature. To derive the results, it was performed analysis such as tensile strength(TS), depolymerization(DP), dielectric strength(DS), relative permittivity, water content(WC) and furan compound(FC) for aged paper. Also for analyzing correlation between insulating degradation characteristics, we used linear regression method. As as results of linear regression analysis, there was a close correlation between TS and DP. WC, FC. But dielectric strength was a weak correlation with aging time.

• 치과방사선
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• 제13권1호
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• pp.29-73
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• 1983

The age related changes in the life cycle of the progenitor cell population of murine oral epithelia was studied. Using radioautographic methods which have been adopted in previous cell cycle studies, the age-related changes of different phases in renewing cells of the palatal, buccal and lingual mucosae were determined. The results confirm published findings on cell cycle changes of epithelia with aging and illustrated further that mitotic phase which has hither to been considered stationary, also changes with aging. The major parts revealed by this study are as follows: 1) The basal progenitor cells in different regions of oral mucosa have different generation times. 2) The basal cell cycle time increases as a function of aging and the region most affected by aging appears to be the epithelium of the cheek. 3) The phases of the cell cycle affected by the process of aging are in increasing order of magnitude: M-, S- and G₁-phase. 4) The age elated change in the number of DNA synthesizing basal progenitor cells occurs at two age periods. Between 1 and 12 months of life it decreases, while from 12 to 20 months it increases.

• 농촌계획
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• 제19권4호
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• pp.203-212
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• 2013

The aging of farm households has caused serious problems such as productivity slowdown and aggravated income polarization in South Korea. Urban-to-rural migration has been recently suggested as a measure to attenuate the aging of rural population and other related problems. The inflow of migrants for farming can have a substantial effect on agriculture and rural communities while the natural adjustment of rural population caused by birth and death is slow. This paper forecasts population distribution of different provinces using the Origin-Destination (OD) analysis, taking into account both the size and directions of migration. In the analysis, nodes where the migration takes place are divided by the industrial sectors (agriculture and non-agriculture), regions, and ages. The results of a ten-year forecast shows that the aging of total population in most provinces will be intensified, but the portion of people over sixty will decrease in the agricultural sector. This finding implies that migration into rural areas, when occurring by a large extent, can mitigate the aging process and attendant problems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1726-1728
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• 2003

The aging diagnosis method using partial discharge measurement detects discharge signals that critical cause of failure in insulation material operated a long time and can diagnose aging state of insulation materials with an aging analysis algorithm. The HFPD measurement method is a technique to analyze aging state of high voltage insulation materials and detect higher frequency signals than conventional PD measurement method therefore it takes less noise effect and could execute active line measurement. It is possible to analyze main discharge phenomena and obtain access to aging progress occurred in insulation materials through accumulation of HFPD signals during determined interval and expression of fractal dimension using statistical process of accumulated signals. The HFPD signals that occurred in each applied voltages are measured during 180 cycles and accumulated to the same phase of one cycle. These patterns that made by previous method are normalized with logarithm function and than inputted to neural networks. The aging diagnosis of insulation material was possible and the recognition ratio of neural network appeared very high.