• International Journal of Oral Biology
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• 제33권4호
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• pp.137-141
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• 2008

The present study reports the protective properties of a total methanol extract of B. platyphylla var. japonica against ultraviolet (UV)-C irradiation. Pretreatment of Chinese hamster fibroblast (V79-4) cells with a total methanol extract significantly increased cell survival following $300\;J/m^2$ of UV-C irradiation. The total methanol extract was further fractionated into 5 fractions: n-hexane, dichloromethane, ethylacetate, n-butanol and water fractions. Among these fractions, B. platyphylla var. japonica ethylacetate, butanol and water fractions showed significant protective effects against the cellular damage induced by UV-C irradiation. In order to elucidate the mechanism underlying this protective effect, DPPH (Editor note: abbreviations should be spelled out at first use.) radical scavenging and lipid peroxidation inhibitory activity were measured. Significant radical scavenging and lipid peroxidation inhibitory activities were observed for the ethylacetate fraction. In summary, the present data demonstrate that an extract of B. platyphylla var. japonica has a significant protective effect against UV-C irradiation. The underlying mechanism of this protective effect may involve radical scavenging and inhibition of lipid peroxidation by the B. platyphylla var. japonica extract.

• 한국철도학회논문집
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• 제12권2호
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• pp.212-218
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• 2009

본 연구에서는 제동시 발생하는 마찰열에 의한 철도차량 디스크의 온도 및 열응력을 유한요소해석을 이용하여 분석하고 동일 차량 디스크의 피로강도를 비교 평가하였다. 해석결과 초기속도 90, 105, 120km/h에서의 제동조건에서 제동했을 경우 디스크 마찰면에서 최대 von-Mise 응력은 각각 42.4, 50.3, 57.1MPa로 90km/h에서 120km/h로 33.3% 증가시 응력은 약 35% 증가하였으며 1년간 서울-부산간의 1회 왕복시 14.6%의 손상율이 발생하는 것으로 평가되어 선형손상법칙을 적용시 수명이 6.85년으로 예상된다.

• ALGAE
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• 제36권3호
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• pp.219-229
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• 2021

The hepatoprotective effect of liposoluble portion of Pyropia yezoensis (PYLP) was investigated against alcohol-induced liver injury in mice. Fatty acids were predominant in PYLP obtained from hexane fraction of 70% EtOH extract after ultrasonication. In particular, polyunsaturated fatty acids such as eicosapentaenoic acid and linoleic acid accounted for 56.91% of the total lipids. PYLP significantly reduced liver damage induced by the alcohol treatment in mice. PYLP treatment increased the activity of antioxidant enzymes including superoxide dismutase, catalase, and glutathion peroxidase by reducing thiobarbituric acid reactive substances. Histological observations showed that PYLP minimizes damage to living tissue induced by alcohol treatment by modulating the expression level of proteins involved in the anti-apoptotic signaling pathway. Our results suggest that PYLP, rich in polyunsaturated fatty acids extracted from the red alga P. yezoensis, will be useful as a potential liver protectant in the hangover industry.

• 한국지진공학회논문집
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• 제25권6호
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• pp.293-303
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• 2021

Seismic fragility functions for unreinforced masonry buildings were derived based on the incremental dynamic analysis of eight representative inelastic numerical models for application to Korea's earthquake damage estimation system. The effects of panel zones formed between piers and spandrels around openings were taken into account explicitly or implicitly regarding stiffness and inelastic deformation capacity. The site response of ground motion records measured at the rock site was used as input ground motion. Limit states were proposed based on the fraction of structural components that do not meet the required performance from the nonlinear static analysis of each model. In addition to the randomness of ground motion considered in the incremental dynamic analysis explicitly, supplementary standard deviation due to uncertainty that was not reflected in the fragility assessment procedure was added. The proposed seismic fragility functions were verified by applying them to the damage estimation of masonry buildings located around the epicenter of the 2017 Pohang earthquake and comparing the result with actual damage statistics.

• 대한금속재료학회지
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• 제47권1호
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• pp.7-12
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• 2009

The detailed quantitative microstructural data on the cracking of coarse constituent particles in 7075 (T651) series wrought Al-alloys have been studied using the utility of a novel digital image processing technique, where the particle cracks are generated due to monotonic loading. The microstructural parameters such as number density, volume fraction, size distribution, first nearest neighbor distribution, and two-point correlation function have been quantitatively characterized using the developed technique and such data are very useful to verify and study the theoretical models for the damage evolution and fracture of Al-alloys. The data suggests useful relationships for damage modeling such as a linear relationship between particle cracking and strain exists for the uniaxial tensile loading condition, where the larger particles crack preferentially.

• Computers and Concrete
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• 제30권4호
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• pp.289-299
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• 2022

Based on the random cracking theory, the cylinder RVE model of reinforced concrete is established and the damage process is divided into three stages as the evolution of the cracks. The stress distribution along longitude direction of the concrete and the steel bar in the cylinder model are derived. The equivalent elastic modulus of the RVE are derived and the user-defined field variable subroutine (USDFLD) for the equivalent elastic modulus is well integrated into the ABAQUS. Regarding the tensile rebars and the concrete surrounding the rebars as the equivalent homogeneous transversely isotropic material, and the FEM analysis for the reinforced concrete beams is conducted with the USDFLD subroutine. Considering the concrete cracking and interfacial debonding, the macroscopic damage process of the reinforced concrete beam under four-point bending loading in the simulation. The volume fraction of rebar and the cracking degree are mainly discussed to reveal their influence on the macro-performance and they are calibrated with experimental results. Comparing with the bending experiment performed with 8 reinforced concrete beams, the bending stiffness of the second stage and the ultimate load simulated are in good agreement with the experimental values, which verifies the effectiveness and the accuracy of the improved finite element method for reinforced concrete beam.

• Nuclear Engineering and Technology
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• 제55권6호
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• pp.2298-2304
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• 2023

Titanium alloys are expected to become one of the candidate materials for nuclear-powered spacecraft due to their excellent overall performance. Nevertheless, atomistic mechanisms of the defect accumulation and evolution of the materials due to long-term exposure to irradiation remain scarcely understood by far. Here we investigate the heavy irradiation damage in a-titanium with a dose as high as 4.0 canonical displacements per atom (cDPA) using atomistic simulations of Frenkel pair accumulation. Results show that the content of surviving defects increases sharply before 0.04 cDPA and then decreases slowly to stabilize, exhibiting a strong correlation with the system energy. Under the current simulation conditions, the defect clustering fraction may be not directly dependent on the irradiation dose. Compared to vacancies, interstitials are more likely to form clusters, which may further cause the formation of 1/3<1210> interstitial-type dislocation loops extended along the (1010) plane. This study provides an important insight into the understanding of the irradiation damage behaviors for titanium.

• 농업과학연구
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• 제45권3호
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• pp.509-519
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• 2018

This study was investigated the anti-oxidant property and neuro-protective effect of Cirsium japonicum var. maackii (CJM) against oxidative stress in hydrogen peroxide ($H_2O_2$)-induced C6 glial cells. We measured the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydroxyl radical (${\cdot}OH$), and superoxide ($O_2{^-}$) radical scavenging activities of an ethanol extract and four fractions [n-Butanol, ethyl acetate (EtOAc), $CHCl_3$, and n-Hexane] from CJM. The results of this study show that the extract and all fractions from CJM had a dose-dependent DPPH radical scavenging activity. In particular, the EtOAc fraction exhibited the strongest scavenging effect with 88.23% at a concentration of $500{\mu}g/mL$. In addition, the EtOAc fraction from CJM also effectively scavenged ${\cdot}OH$ radicals and $O_2{^-}$ radicals, compared to other extract and fractions. In C6 glial cells, $H_2O_2$ markedly decreased the cell viability as well as increased lactate dehydrogenase (LDH) release and reactive oxygen species (ROS) production. However, the EtOAc fraction of CJM attenuated the cellular damage from the oxidative stress by elevating the cell viability and inhibiting the LDH release and ROS over-production compared with the $H_2O_2$-treated control group. Our findings indicate that the EtOAc fraction from CJM has antioxidant effect and neuro-protective effect against oxidative stress, suggesting that it can be used as a natural antioxidant and therapeutic agent for the prevention of neurodegenerative disorders.

• Journal of Nutrition and Health
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• 제31권9호
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• pp.1385-1393
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• 1998

The hypoglycemic effects of butanol(BuOH) fraction of Polygonatum odoratum with vitamin E in streptozotocin(STZ)-induced diabetic rats were investigated. Sprague-Dawley rats weighing 200-230g were devided into five groups, and four groups induced diabetes mellitus by the STZ injection(45mg/kg b.w.) into the tail vein : Normal, diabetic-control, and three diabetic experimental groups(p. odoratum group, P. od-vit. E group and Vit. E group). All groups were fed on a AIN-76 diet, and the experimental groups were orally administered with the BuOH fraction of Polygonatum odoratum(500mg/kg b.w.) and vitamin E(10mg/kg b.w.) for 14 days. The body weight, diet intake and organ weights were monitored. The plasma levels of glucose, insulin, cholesterol, triglyceride, HDL-cholesterol and aspartate and alanine aminotransferase activities were analyzed. The levels of glycogen in liver and muscle, cholesterol in liver were determined. The malondialdehyde(MDA) levels in liver, kidney and lung were assayed. The body weight loss was seen in P. odoratum group, P. od-vit. E group, Vit. E group and diabetic control group, while the loss in P. odoratum group was much less than that in the diabetic control group. The plasma glucose levels were significantly lowered in P. odoratum group compared to diabetic control group. The plasma insulin levels were noticeably higher in P. odoratum and Vit. E groups. The rats in P. odoratum and P. od-vit. E group showed higher liver glycogen levels than in the diabetic control group. The MDA levels in liver, kidney and lung were also significantly reduced in P. od-vit. E and Vit. E groups compared to the diabetic control group. The results suggest that the administration of BuOH fraction of Polygonatum odoratum along with vitamin E reduced blood glucose levels and peroxidative tissue damage in STZ-induced diabetic rats, showing the possibility of preventive and therapeutic use of the wild edible plant to the diabetes mellitus. (Korean J Nutrition 31(9) : 1385-1393, 1998)

• 동의생리병리학회지
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• 제25권4호
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• pp.628-634
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• 2011

The roots of Polygala tenuifolia Willd. is a well-known traditional medicine used as expectorant, tonic, tranquilizer in Asia including China and Korea. And also have been used to treat amnesia, neurasthenia, palpitation, insomnia, and disorientation. Glutamate-induced oxidative injury contributes to neuronal degeneration in many central nervous system (CNS) diseases, such as Parkinson's disease, Alzheimer's disease, epilepsy and ischemia. Inducible heme oxygenase (HO)-1 acts against oxidants that are thought to play a role in the pathogenesis of these diseases. NNMBS269, acid hydrolysis EtOAc fraction of the P. tenuifolia showed dominant neuroprotective effects on glutamate-induced neurotoxicity in mouse hippocampal HT22 cells while general EtOAc fraction of the P. tenuifolia (NNMBS268) not shown. NNMBS269 induced the expression of HO-1 protein that has been proposed to play an important cellular defense role against oxidant injury. In addition increased HO activity. In mouse hippocampal HT22 cells, NNMBS269 makes the nuclear accumulation of nuclear factor E2-related factor 2 (Nrf2). In conclusion, acid hydrolysis EtOAc fraction the P. enuifolia. (NNMBS269) significantly protect glutamate-induced oxidative damage by induction of HO-1 via Nrf2 translocation in mouse hippocampal HT22 cells.