• Journal of the Korean Society for Railway
• /
• v.20 no.3
• /
• pp.320-328
• /
• 2017

In order to analyze the influence on derailment safety according to the aging of primary rubber springs widely applied to railway vehicles, characteristic tests were carried out on aged primary rubber spring samples. To analyze the effect of primary rubber spring aging on derailment safety, a vehicle dynamic analysis was carried out. The results of the vertical characteristics test for the rubber spring specimens with 17 years of service life revealed that the displacement restoration function was degraded due to rubber aging and the spring stiffness significantly increased. The results of the running dynamic analysis simulating the twist track running in accordance with the EN14363 standard, compared with the normal vehicle model (Case 1), showed that the derailment coefficient and the wheel unloading of the vehicle model (Case 2) using the aging primary spring characteristic increased, and the derailment safety was degraded. IN particular, it was found that the derailment safety due to the reduction of the wheel load is weak in the transient section where a steep slope change occurs.

• Sleep Medicine and Psychophysiology
• /
• v.4 no.1
• /
• pp.29-38
• /
• 1997

Dementia is defined as a syndrome which is characterized by various impairments in cognitive functions, especially memory function. Most of the diagnostic criteria for dementia include memory impairment as on essential feature. Memory decline can be present as a consequence of the aging process. But it does not cause significant distress or impairment in social and occupational functionings while dementiadoes. Depression may also be associated with memory impairment. However, unlike dementia, depression dose not cause decrease in delayed verbal learning and recognition memory. In dementia, different features of memory impairment may be present depending on the involved area. Memory impairment in cortical dementia is affected by the disturbance of encoding of information and memory consolidation, while memory imparnene in subcortical denentiy is affected by the disturbance of retrieval in subcortical dementia.

• Proceedings of the KSLP Conference
• /
• 1996.11a
• /
• pp.77-77
• /
• 1996

성대구조는 연령변화에 따라 조직학적인 변화가 일어나게 된다. 이에 따른 음성의 노화현상을 알아보고자 Multi-Dimensional Voice Program(Model 4305, Kay Elemetrics Corp, USA)을 이용하여 모든 연령층에서 정상적인 목소리와 성대에 병변이 없는 300명(남자141명, 여자159명)을 대상으로 다차원음향분석 지표의 연령변화에 따른 양적변화를 측정하여 연령에 따른 음향분석지표의 정상기준치와 음성지표의 연령별 변화를 밝혀내려 하였다. (중략)

• Applied Microscopy
• /
• v.36 no.2
• /
• pp.119-130
• /
• 2006

To investigate the role of myelin-associated glycoprotein (MAG) in the normal aging process, aging-related morphometric and ultrastructural analyses of the MAG-positive (MAG-(+)) oligodendrocytes were carried out in the cerebral cortex of the Sprague-Dawley rats. In the aged rats, the density of MAG-(+) oligodendrocytes was significantly decreased in the cortical layer (IV-VI) compared with that of the adult rats. However, the percentage of medium and dark types of oligodendrocytes was significantly increased by aging. In the aged rats, the mean nuclear area of the MAG-(-) oligodendrocytes was interestingly reduced compared with that of MAG-(+) oligodendrocytes. In addition, MAG immunoreactive products were markedly decreased in the medium-dark type of oligodendroglial cytoplasm and processes, and were scarcely localized in the dark type of oligodendrocytes of the aged rats. These results suggest that degeneration of oligodendrocytes-myelin system by aging is associated with down regulation of MAG, and that may contribute to further understanding of the biology of MAG in the oligodendrocytes-myelin system.

• Journal of Life Science
• /
• v.12 no.3
• /
• pp.349-356
• /
• 2002

In order to observe the bioactivity of ovariectomized rats, nonovariertoized (sham) group, ovariectomized (Ovx) group, ovariectomized ginseng total saponin (GTS)-treated (Ovx+ GTS) group and ovariectomized ginseng water extract (GW)-treated (Ovx+CW) group were made. We measured AST (L-aspartate aminotransferase) and ALT (L-alanin aminotransferase) in sera, and MDA (malondialdehyde:lipid peroxidation), SOD (superoxide dismutase), catalase, total-glutathione (GSH + GSSG) and GPx (glutathione peroxidase) in liver tissue total homogenates of rat. AST activity of serum in Ovx group was 2.11 times increased, but ALT activity was not changed compared to Sham group. In AST activity, they tend to decrease significantly in each substance such as GTS and GW administered group. Lipidperoxides of each fraction in Ovx group were highly increased compared to Sham group. Extracts of ginseng-treated group markedly inhibited lipid peroxidation by 62% ∼72%. And as the result of the measurements of SOD, catalase, total-glutathione and GPx which are antioxidant enzyme, antioxidant enzymes in Ovx group much lower than in Sham group. But they were significantly increased in each substance such as GTS and GW, administered group. Based on the results, it is supposed that more produced free radicals decreased antioxidant enzyme. And it is also thought that extracts of ginseng can inhibit aging by reducing antioxidant enzyme.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2009.08a
• /
• pp.55-55
• /
• 2009

• Journal of the Korean Society of Propulsion Engineers
• /
• v.24 no.6
• /
• pp.101-107
• /
• 2020

In this paper, step-curing, which includes the change of curing temperature on the curing process, was applied to reduce curing day of HTPB/AP based propellant. This study targets the improvement of productivity of HTPB/AP based solid rocket motor. Comparison of mechanical properties of propellant resulted in the change of normal curing condition (60℃, 5 days) to step-curing condition (60℃, 1 day / 65℃, 3 days). Post-cure test was conducted to determine the impact on the shelf life of the solid rocket motor. The aging characteristics of propellants were analyzed by measuring mechanical properties and thermal expansion factor. To step-cured propellant, accelerated aging test was performed for 12 weeks, followed by tensile test. Sm(bar) and Em(%) were higher than 8 bar and 40% each, showing excellent mechanical properties.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.30 no.1
• /
• pp.135-140
• /
• 2004

Anti-skin aging agent could be have an inhibition effect of ROS production as well as fragmentation and change of collagen cross linkage in collagen molecule. For the monitoring of lipid peroxidation and collagen degradation, the skin of young and old rats were incised and observed 7 days. In the result, the wound closure was observed in the skin from 10 of 11 young rats and in 8 of 11 old rats. And the longer wound length but shorter wound closure, weaker collagen density and thicker epidermis were observed in old rats than in young rats. The level of hydroxyproline as a parameter of collagen synthesis and MDA as a parameter of lipid peroxidation was lower in old group than in young group. The cyst and lacuna between collagen bundle and fibroblast were observed in old rats in contrast to young rats. So that we propose that MDA and hydroxyproline could be used for monitoring of anti-skin aging agent.

• Korean Journal of Plant Resources
• /
• v.23 no.2
• /
• pp.157-164
• /
• 2010

Rosa rugosa has been used as a folk medicine with various pharmacological properties for a long time in Asia. We investigated effects of fructus extracts of Rosa rugosa (RRF) and semen extracts of this herb (RRS) on bone forming cells (osteoblastic and pre-osteoclastic cells) to evaluate the pharmacological possibilities in a variety of bone-related disease. RRF showed significant effect on proliferation of osteoblastic cells in dose-dependent manners at 72 hrs and $100\;{\mu}g/m{\ell}$ of RRS was effective at 48 and 72 hrs. RRF and RRS did not decreased production of TNF-$\alpha$ but NO by pre-osteoclastic cells under inflammation circumstance indeced by LPS. We also investigated the effects of RRF and RRS on the mitogen-induced lymphocyte proliferation in the old and young mice in ex vivo systems. RRF and RRS significantly enhanced proliferative effects of untreated and ConA-treated splenocytes from the old and young mice. But, RRS at $500\;{\mu}g/m{\ell}$ increased LPS-induced TNF-$\alpha$ production in pre-osteoclastic cells and reduced LPS-stimulated lymphoblastogenesis in the old and young at $1000\;{\mu}g/m{\ell}$. These results indicate that RRF has beneficial effects on osteoarthritis and give further possibilities for the immunomodulating effects not only in old that has more frequent bone related diseases but also in young.

• Applied Microscopy
• /
• v.30 no.4
• /
• pp.327-335
• /
• 2000

The aim of this study was to discover whether Yukmijihwangtang which was added Plygalae Radix, Acori graminei Rhizoma, has antioxidant effects on aged senescence-accelerated mouse (SAM) P8. The control group used 12 months old SAM P8 and the experimental group was treated with Yukmijihwangtang extracts from 8 to 12 months old. In the liver, the MnSOD of the control group were approximately 11% higher than that of the experimental group treated with herbal extracts, but CuZnSOD activities of the experimental group were approximately 20% higher than that of the control group. The catalase activities of the experimental group was approximately 67% higher than that of the control group. The hepatocytes, in the control group compared with the experimental group, contained the dilated cisternae of rough endoplasmic reticulum and the abnormal mitochondira which had electron-dense matrix and indistinguishable cristae. The inner cavity of the smooth endoplasmic reticulum were slightly dilated, and a number of vacuoles and transitional vesicles occured in of the hepatocytes of the control group. These results suggest that the herbal extract has an antioxidant effects on the liver of SAM P8.