• Journal of the Korean Ceramic Society
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• v.49 no.3
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• pp.231-235
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• 2012

Plasticity is the ability of clay to respond to pressure with a continuous and permanent change of shape in any direction without breaking apart, and hold that shape when released. In this work, the effect of water content and aging period on the plasticity of porcelain clay was evaluated using the capillary rheometer to measure the flow rate and the shear stress. The shear stress of porcelain clay was slightly increased with increasing the aging period, indicating that the plasticity of porcelain clay was influenced by an organic content. It was also observed that the water content in the porcelain clay had a great influence on the plasticity of porcelain clay. The shear stress with water content of 21 wt% was sharply increased with increasing shear rate, but the shear stresses with water contents of 24 and 27 wt% is gently incremented.

• BMB Reports
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• v.54 no.5
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• pp.253-259
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• 2021

Aging is characterized by a functional decline in most physiological processes, including alterations in cellular metabolism and defense mechanisms. Increasing evidence suggests that caloric restriction extends longevity and retards age-related diseases at least in part by reducing metabolic rate and oxidative stress in a variety of species, including yeast, worms, flies, and mice. Moreover, recent studies in invertebrates - worms and flies, highlight the intricate interrelation between reproductive longevity and somatic aging (known as disposable soma theory of aging), which appears to be conserved in vertebrates. This review is specifically focused on how the reproductive system modulates somatic aging and vice versa in genetic model systems. Since many signaling pathways governing the aging process are evolutionarily conserved, similar mechanisms may be involved in controlling soma and reproductive aging in vertebrates.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.290.1-290.1
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• 2002

The surgically ovariectomized rat induces aging by reactive oxyyen species(ROS) generation. Free oxygen radicals have been proposed as important causative agents of aging. The purpose of this study was to investigate the effect of Chondroitin Sulfate(CS) to prevent ovariectomy(OVX) induced oxidative stress and atherosclerosis. The OVX rats were given intraperitoneally CS at dose of 100mg/kg and 200mg/kg daily for fifteen weeks. (omitted)

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.2
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• pp.45-50
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• 2005

To improve mean-life and reliability of power cable, in this study, we have investigated electrical properties and stress-strain showing by changing the content of carbon black that is semiconductive additives for underground power transmission. Specimens were made of sheet form with the nine of specimens for measurement. Volume resistivity of specimens was measured by volume resistivity meter after 10 minutes in the pre-heated oven of both 25±1 [℃] and 90±1 [℃]. And stress-strain of specimens was measured by TENSOMETER 2000. A speed of measurement was 200[mm/min], ranges of stress and strain were 400[Kgf/㎠] and 600[%]. In addition tests of stress-strain were progressed by aging specimens in air oven. From this experimental results, volume resistivity was high according to increasing the content of carbon black. And yield stress was increased, while strain was decreased according to increasing the content of carbon black. And stress-strain were decreased some after aging because of oxidation reaction of chemical defect. We could know EEA was excellent more than other specimens from above experimental results.

• Journal of Integrative Natural Science
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• v.16 no.3
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• pp.75-80
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• 2023

Bipolar disorder is a mental illness characterized by extreme mood and behavioral swings, such as highs of euphoria and lows of depression. It is a socially significant disorder in which people with the disorder experience intense mood swings and, for those with severe bipolar disorder, it is even difficult leading a normal life. High stress levels in people with mental illness can lead to neuroendocrine disruption, and it is strongly linked to aging. When the neuroendocrine system becomes vulnerable to these mental illnesses and stress, it is likely to accelerate aging. And it's the epigenetic clock that can measure the extent of this accelerated aging. The Epi clock, a pan tissue clock, measures aging through DNA methylation, and the degree of methylation is modified and changed by environmental conditions in the body. Therefore we wanted to check the changes in the epigenetic age of the patients with bipolar disorder. While we found no significant differences in epigenetic age, we did confirm the possibility that people with bipolar disorder have different methylation than normal people. We also found that the EPIC array data fit better on the Epi clock than on the Horvath clock with age-accelerated data from normal people.

• Journal of Society of Preventive Korean Medicine
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• v.8 no.1
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• pp.109-114
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• 2004

Oxidative stress is one of the major reasons for brain aging and neurodegeneration. Ethanol and acetaldehyde increase the levle of oxidative stress in brain tissue resulting in aging and neurodegeneration related alcoholic dementia. Ginkgo biloba extracts are used as therapeutic and preventive agent for dementia. Here, it was investigated whether Ginkgo biloba extract show the effectiveness against ethanol- and acetaldehyde-induced oxidative stress in rat brain. Ethanol and acetaldehyde increased the level of oxidative stress by about 35% to 50% in rat brain tissue. However, Ginkgo biloba extracts reduced the level of ethanol- and acetaldehyde-induced oxidative stress. This result might reveal the link between the effectiveness of Ginkgo biloba extracts on oxidative stress and its effectiveness on alcoholic dementia.

• BMB Reports
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• v.41 no.11
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• pp.751-756
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• 2008

Aging and cancer both occur as a result of accumulated cellular damage, and both are related to the regulation of specific genes in the damage response. Recent research has unveiled connections between the mechanisms of aging and cancer, but how to prevent the development of cancer and increase longevity remain unknown. SIRT1 (the mammalian Sir2), which has $NAD^+$-dependent class III histone deacetylase activity, may be a key gene linking the modulation of cancer and aging. SIRT1 has broad biological functions in growth regulation, stress response, tumorigenesis, endocrine signaling, and extended lifespan. Here, we focus on the current knowledge regarding the role of SIRT1 in aging and cancer, and discuss the implications of SIRT1 as a therapeutic target for the optimal balance between anti-aging and anti-cancer activities.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.596-598
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• 2000

This paper presents a new accelerating aging test facility for distribution lightning arresters. Aging parameters of lightning arrester are moisture ingress, electrical stress and surge absorption and so on. In this system, we applied 13.2kV to 6 samples and controled temperature and humidity of chamber and measured leakage currents of the all samples. Also we developed accelerating aging cycle which consists of -35$^{\circ}C$∼90$^{\circ}C$ temperature and 40%∼90% humidity. Through the aging test we found out the leakage current of aged sample increases rapidly according to the temperature rising. Hereafter we can determine the replacement guide of leakage current for field operating arresters and condition assessment of aged samples through this aging test.

• Nutrition Research and Practice
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• v.8 no.5
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• pp.526-532
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• 2014

BACKGROUND/OBJECTIVES: Acanthopanax sessiliflorus is a native Korean plant and used as a traditional medicine or an ingredient in many Korean foods. The free radical theory of aging suggests that cellular oxidative stress caused by free radicals is the main cause of aging. Free radicals can be removed by cellular anti-oxidants. MATERIALS/METHODS: Here, we examined the anti-oxidant activity of Acanthopanax sessiliflorus extract both in vitro and in vivo. Survival of nematode C. elegans under stress conditions was also compared between control and Acanthopanax sessiliflorus extract-treated groups. Then, anti-aging effect of Acanthopanax sessiliflorus extract was monitored in C. elegans. RESULTS: Stem extract significantly reduced oxidative DNA damage in lymphocyte, which was not observed by leaves or root extract. Survival of C. elegans under oxidative-stress conditions was significantly enhanced by Acanthopanax sessiliflorus stem extract. In addition, Acanthopanax sessiliflorus stem increased resistance to other environmental stresses, including heat shock and ultraviolet irradiation. Treatment with Acanthopanax sessiliflorus stem extract significantly extended both mean and maximum lifespan in C. elegans. However, fertility was not affected by Acanthopanax sessiliflorus stem. CONCLUSION: Different parts of Acanthopanax sessiliflorus have different bioactivities and stem extract have strong anti-oxidant activity in both rat lymphocytes and C. elegans, and conferred a longevity phenotype without reduced reproduction in C. elegans, which provides conclusive evidence to support the free radical theory of aging.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.695-700
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• 1999

Effects of two-step aging treatment on the stress corrosion cracking(SCC) resistance of 7050 Al alloy were investigated by transmission electron microscopy, electrical conductivity measurement and stress corrosion facter(SCF) evaluation. It was found that η', principal hardening phase, transformed to η during over aging above maximum hardness, and SCC resistance was improved by increasing of the size and interspacing of η particles in matrix and grain boundary. The electrical conductivity increased with aging time, but SCF decreased due to the decrease of yield strength. This results mean increase of SCC resistance The optimum two-step aging condition in forged 7050 Al alloy was to be first aged at $120^{\circ}C$ for 6h and then finally aged at $175^{\circ}C$ for 12h.