• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.467-471
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• 2001

DC accelerated aging characteristics of $Pr_{6}O_{11}$-based ZnO varistors, which are composed of $ZnO+Pr_{6}O_{11}+CoO+Cr_{2}O_{3}+Dy_{2}O_{3}$ ceramics were investigated with CoO content in the range of 0.5 - 5.0 mol%. The varistors doped with 1.0 mol% revealing maximum value(66.61) in the nonlinear exponent exhibited excellent stability, in which the variation rates of the varistor voltage, the nonlinear exponent and leakage current are -1.93%, -10.48%, and +288.79%, respectively, under DC accelerated aging stress, such as $(0.85V_{lmA}/115^{\circ}C/24h)+(0.90V_{lmA}120^{\circ}C/24h)+(0.95V_{lmA}/125^{\circ}C/24h)+(0.95V_{lmA}/150^{\circ}C/24h)$. Next the varistors doped with 2.0 mol% exhibiting the nonlinear exponent of 47.39 showed high stability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.467-471
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• 2001

DC accelerated aging characteristics of Pr$_{6}$O$_{11}$-based ZnO varistors, which are composed of ZnO+Pr$_{6}$O$_{11}$+CoO+Cr$_2$O$_3$+Dy$_2$O$_3$ ceramics were investigated with CoO content in the range of 0.5~5.0 mol%. The varistors doped with 1.0 mol% revealing maximum value(66.61) in the nonlinear exponent exhibited excellent stability, in which the variation rates of the varistor voltage, the nonlinear exponent and leakage current are -1.93%, -10.48%, and 288.79%, respectively, under DC accelerated aging stress, such as (0.85 V$_{1mA}$/115$^{\circ}C$/24h)+(0.90 V$_{1mA}$/12$0^{\circ}C$/24h)+(0.95 V$_{1mA}$/1$25^{\circ}C$/24h)+(0.95 V$_{1mA}$/15$0^{\circ}C$/24h). Next the varistors doped with 2.0 mol% exhibiting the nonlinear exponent of 47.39 showed high stability,ity,ability,ity,

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.659-659
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• 2003

In this study, we have investigated the potent anti-aging effect of DA-3711, a cosmetic ingredient derived from artificial skin culture. The artificial skin was originally developed as a skin replacement for the treatment of chronic skin wounds. To produce DA-3711, neonatal human fibroblasts were seeded into biocompatible collagen/chitosan/glycosaminoglycan (GAG) scaffolds and cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with fetal bovine serum and nonessential amino acids. Analysis of the culture broth (DA-3711) showed that growth factors such as VEGF, TGF-$\beta$, KGF were present at significantly higher levels that in the culture broth of fibroblasts cultured in monolayer. The biological activity of DA-3711 was assessed by measuring in vitro cell proliferation and collagen synthesis of normal human fibroblasts. Fibroblasts treated with 10％ DA-3711 showed a 2-fold higher proliferation and 2 to 4-fold higher collagen synthesis than untreated cells. DA-3711 also exhibited anti-oxidative effects, since cells under peroxide-induced oxidative stress showed a 30％ higher viability in DA-3711-containing medium than in medium without DA-3711 addition. The results suggest that DA-3711 may have anti-aging effects by stimulating skin regeneration and protecting against oxidative stress.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2332-2334
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• 1999

This paper presents the results of multi-stress chamber experiments done to examine the tracking and erosion performance of polymer insulator. Multi-stress testing is able to demonstrate deficiencies of polymer insulator materials and designs including the nature of interfaces in insulation design. Therefore, multi-stress testing is believed to a suitable test for evaluating the aging performance of polymer insulator designs. We have investigated IEC 61109 Annex C for estimating long time performance of polymer insulator.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.11-17
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• 1999

Aging characteristics of the crosslinked polyethylene have been measured after applying electrical, thermal and combined stresses. ICP and FT-IR measurements confirmed diffusion of low molecular weight components such as antioxidant and presence of carbonyl group. Carbonyl group of aged crosslinked polyethylene under combined stress was detected by FT-IR. As deterioration of the crosslinked polyethylene progresses, crystallinity degree and density decrease. Also, dielectric properties have been measured by tan $\delta$ and $\varepsilon$$_{r}$ measurements. The three-parameter Weibull distribution was found to be the best suited among other probabilistic distribution representing the dielectric breakdown strength of aged crosslinked polyethylene. The scale parameter and location parameter decreases as the applied stress increases. The shape parameter increases as the stress increases.s.

• Biomolecules & Therapeutics
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• v.23 no.6
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• pp.582-589
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• 2015

Several theories emphasize that aging is closely related to oxidative stress and disease. The formation of excess ROS can lead to DNA damage and the acceleration of aging. Vigna angularis is one of the important medicinal plants in Korea. We isolated vitexin from V. angularis and elucidated the lifespan-extending effect of vitexin using the Caenorhabditis elegans model system. Vitexin showed potent lifespan extensive activity and it elevated the survival rates of nematodes against the stressful environments including heat and oxidative conditions. In addition, our results showed that vitexin was able to elevate antioxidant enzyme activities of worms and reduce intracellular ROS accumulation in a dose-dependent manner. These studies demonstrated that the increased stress tolerance of vitexin-mediated nematode could be attributed to increased expressions of stress resistance proteins such as superoxide dismutase (SOD-3) and heat shock protein (HSP-16.2). In this work, we also studied whether vitexin-mediated longevity activity was associated with aging-related factors such as progeny, food intake, growth and movement. The data revealed that these factors were not affected by vitexin treatment except movement. Vitexin treatment improved the body movement of aged nematode, suggesting vitexin affects healthspan as well as lifespan of nematode. These results suggest that vitexin might be a probable candidate which could extend the human lifespan.

• Applied Microscopy
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• v.28 no.1
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• pp.21-38
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• 1998

The present study was performed to determine the effect of cold stress on myocardium of aging rat. Control groups, which aged 6, 12 and 24 months, were compared with age-matched experimental groups that were exposed to moderate cold stress for a hours daily in a week at laboratory cold room $(4{\pm}1^{\circ}C)$. The histological, histochemical and ultrastructural changes of myocardium were observed. The results were summarized as follow: 1. Age-dependent histological change of control groups was observed the formation of contraction band in 24months aged group. The experimental groups submitted to cold stress showed a similar change pattern as seen in control groups. However, the degree of change in the experimental groups was significantly larger than that of control groups. In the 34 months aged group the formation of hypercontraction band was observed. 2. Regarding age-dependent histochemical changes of control groups, we observed the increase activities of PAS and Masson's trichrome. In experimental groups the activities of PAS and Masson's trichrome were also increased with age. Compare with control group, the activities of PAS was increased but the activities of Masson's trichrome was decreased. 3. Age-dependent ultrastructural changes on vacuolization, lysosome were observed. In control groups the structural changes occur at 12 months. The accumulation of lipofuscin, contraction band, hypercontraction band and a component of connective tissue were observed in 24 months. However, the degree of change in the experimental groups was significantly larger than that of control groups. In contract, the myelin body in intercalated discs was observed in 24 months of experimental groups.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.4
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• pp.241-251
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• 2019

Purpose : The purpose of this study was to investigate the depression, self-efficacy, and stress level of middle-aged women and to identify the factors affecting on stress, and to provide base line data for the development of nursing intervention for stress reduction of middle-aged women. Methods : Participants were 200 middle-aged women aged 40 to 60 who live in Seoul and Gyeonggi Province. Data collection period was from March 1, 2019 to April 15. In this study, the questionnaire of life events-stress, depression scale, self-efficacy was used. Data were analyzed by average, standard deviation, minimum, maximum, correlation and regression using the SPSS Program 21.0. Results : The results of this study, the correlation between depression, self-efficacy and stress in middle-aged women, depression and self-efficacy (r=-.264, p<.001), self-efficacy and stress (r=-.279, p<.001) had a significant negative correlation, depression and stress (r=.268, p<.001) had a significant positive correlation. Depression and self-efficacy were the factors affecting the stress of middle-aged women. Depression was β =.207 (p<.001) and self-efficacy β =-.222 (p=.003). Depression had the greatest influence on stress, followed by self-efficacy. Conclusion : Middle-aged women are an important time to prepare for a successful old age. Considering that the current middle-aged women are the subjects of the future aging society, their physical, psychological, and social problems are very important in preventing the elderly problems of the aging society. Therefore, effective nursing interventions should be developed that to reduce the depression and stress in middle-aged women and to improve self-efficacy and improve the quality of life of middle-aged women.

• IMMUNE NETWORK
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• v.19 no.1
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• pp.3.1-3.17
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• 2019

Aging is a complex process associated with dysregulation of the immune system and low levels of inflammation, often associated with the onset of many pathologies. The lacrimal gland (LG) plays a vital role in the maintenance of ocular physiology and changes related to aging directly affect eye diseases. The dysregulation of the immune system in aging leads to quantitative and qualitative changes in antibodies and cytokines. While there is a gradual decline of the immune system, there is an increase in autoimmunity, with a reciprocal pathway between low levels of inflammation and aging mechanisms. Elderly C57BL/6J mice spontaneously show LGs infiltration that is characterized by Th1 but not Th17 cells. The aging of the LG is related to functional alterations, reduced innervation and decreased secretory activities. Lymphocytic infiltration, destruction, and atrophy of glandular parenchyma, ductal dilatation, and secretion of inflammatory mediators modify the volume and composition of tears. Oxidative stress, the capacity to metabolize and eliminate toxic substances decreased in aging, is also associated with the reduction of LG functionality and the pathogenesis of autoimmune diseases. Although further studies are required for a better understanding of autoimmunity and aging of the LG, we described anatomic and immunology aspects that have been described so far.