• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.903-907
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• 1996

Under two level block loading, the carbornitrizing specimen can be expected to show different behavior from other uniform material because the properties of surface layer and inner material are different from each other. In this research, the modified Marco-Starkey cumulative theory, which considers load interaction effect, can predict the life of SCM415 carbornitrizing and original notched and smooth specimen, In the low-high test of carbornitrizing specimen which has long life, however, we may additionally consider the increase of life by means of the stress hardening of inner original material.

• Journal of Ocean Engineering and Technology
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• v.13 no.3 s.33
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• pp.100-107
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• 1999

Due to the high temperature and pressure, the materials of pipeline in power plant are degraded by creep damage. So far, many conventional measurement techniques such as replica method, electric resistance method, adn hardness test method for creep damage have been used. Among them, the replica method has mainly been used for the inspection of components. But this technique is restricted to the applications at the surface of the objects and cannot be used to material inside. In this paper, the measuring methods of evaluation by using ultrasonic attenuation and electric resistance for the creep detection of creep damage in the form of cavities on grain boundaries or intergranular microcracks were carried out. Absolute measuring method of quantitave ultrasonic attenuation technique for 1Cr0.5Mo material degradation was analyzed for determining the creep degradation steps using life prediction formula. As a result of measurement for creep specimens, we founded that the coefficient of utrasonic attenuation was increased as the increase of creep life fracton(${phi}c$) and the decreasing rate of wlwctric resistance was also increased.

• Steel and Composite Structures
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• v.32 no.6
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• pp.701-715
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• 2019

Using first-order shear deformation theory (FSDT), a semi-analytical solution is employed to analyze creep damage and remaining life assessment of 304L austenitic stainless steel thick (304L ASS) cylindrical pressure vessels with variable thickness subjected to the temperature gradient and internal non-uniform pressure. Damages are obtained in thick cylinder using Robinson's linear life fraction damage rule, and time to rupture and remaining life assessment is determined by Larson-Miller Parameter (LMP). The thermo-elastic creep response of the material is described by Norton's law. The novelty of the present work is that it seeks to investigate creep damage and life assessment of the vessels with variable thickness made of 304L ASS using LMP based on first-order shear deformation theory. A numerical solution using finite element method (FEM) is also presented and good agreement is found. It is shown that temperature gradient and non-uniform pressure have significant influences on the creep damages and remaining life of the vessel.

• Korean Journal of Plant Resources
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• v.29 no.2
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• pp.163-170
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• 2016

Antioxidant activity and inhibitory effect on oxidative DNA damage of ethyl acetate fractions extracted from Cone of Red Pine (Pinus densiflora) were investigated to find utilization of Cone, by-product of Red Pine, thrown out after berry shatter, as a new natural plant resource. Cone from P. densiflora was extracted with methanol (MeOH) and separated to petroleum ether, ethyl acetate and water fraction. Among them, ethyl acetate fraction was used. The antioxidant activity was conducted by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical, 2, 2'-Azino-bis (3-ethylbenzothiazoline-6 sulfonic acid) diammonium salt (ABTS) radical scavenging assay, Fe²⁺ chelating assay and reducing power assay. The inhibitory effect on oxidative DNA damage was determined by DNA cleavage assay using φX-174 RF I plasmid. The results of DPPH and ABTS radical scavenging activity at 200 ㎍/㎖ of extracts were 86.50% and 95.80% respectively, which were similar figures compared with L-ascorbic acid as control. Fe²⁺ chelating activity was 77.96% and reducing power was 0.77 at 200 ㎍/㎖. Total phenolic component was 27.29±0.3 ㎎/g and Vitamin C content was 1.84±0.1 ㎎/g. Also ethyl acetate fraction from Cone has inhibitory effect, using φX-174 RF I plasmid on DNA cleavage assay. In conclusion, Cone, by-product of P. densiflora, showed high antioxidant activity and inhibitory effect on oxidative DNA damage. Therefore this study suggests Cone, useless by-product, can be developed as a new natural plant resource with lots of utilization such as an effective antioxidant, natural medicine, food, cosmetics and so on.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.8
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• pp.1241-1247
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• 2015

The objective of this study was to determine antioxidant properties of polyphenol fractions of cranberry powder employing lipopolysaccharides (LPS)-stimulated RAW264.7 macrophage cells. Ethyl acetate fraction (EF) and methanol fraction (MF) of cranberry powder were prepared using a C18 Sep-Pak cartridge. When cells were treated with LPS for 20 h, intracellular reactive oxygen species (ROS) and DNA damage significantly increased. In cells pre-treated with EF, MF, and total fraction (TF: combining EF and MF), significant reductions of intracellular ROS were observed. The tested fractions reduced LPS-induced DNA damage measured by Hoechst staining. In addition, LPS-induced DNA oxidation was attenuated when cells were pre-treated with TF and MF. However, there was no significant difference in LPS-induced superoxide dismutase activity.

• Biomolecules & Therapeutics
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• v.15 no.4
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• pp.205-211
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• 2007

The fruits and stems of Opuntia ficus-indica var. saboten have been reported to exhibit a variety of pharmacological actions, including antioxidant, analgesic, anti-inflammatory, and anti-ulcer effects. In the present study, we evaluated effects of the butanol fraction (SK OFB901) prepared from the 50% ethanol extract of the stems on various types of neuronal injuries induced by oxidative stress, excitotoxins, and amyloid ${\beta}\;(A_{\beta})$ in primary cultured rat cortical cells. Its antioxidant and radical scavenging activities were also evaluated by cell-free bioassays. We found that SK OFB901 strongly inhibited the oxidative neuronal damage induced by $H_2O_2$ or xanthine/xanthine oxidase. In addition, it exhibited marked inhibition of the excitotoxic neuronal damage induced by glutamate, N-methyl-D-aspartic acid, or kainate. Furthermore, the $A_{\beta(25-35)}$-induced neurotoxicity was also significantly attenuated by SK OFB901. It was found to inhibit lipid peroxidation initiated by $Fe^{2+}$ and L-ascorbic acid in rat brain homogenates and scavenge 1,1-diphenyl-2-picrylhydrazyl free radicals. These results indicate that the butanol fraction prepared from the stems of Opuntia ficus-indica var. saboten exerts potent antioxidant and neuroprotective effects through multiple mechanisms, implying its potential applications for the prevention or management of neurodegenerative disorders associated with oxidative stress, excitotoxicity, and $A{\beta}$.

• Korean Journal of Pharmacognosy
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• v.42 no.3
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• pp.276-281
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• 2011

Oxidative stress or the accumulation of reactive oxygen species (ROS) leads neuronal cellular death and dysfunction, and it contributes to neuronal degenerative disease such as Alzheimer's disease, Parkinson's disease and stroke. Glutamate-induced oxidative injury contributes to neuronal degeneration in many central nervous system (CNS) diseases, such as epilepsy and ischemia. Heme oxygenase-1 (HO-1) enzyme plays an important role of cellular antioxidant system against oxidant injury. The expression of HO-1 has cytoprotective effects in glutamate-induced oxidative cytotoxicity in HT22 cells. The induction of HO-1 is primarily regulated at the transcriptional level, and its induction by various inducers is related to the nuclear transcription factor-E2-related factor 2 (Nrf2). Nrf2 is a master regulator of the antioxidant response. NNMBS008, the water-insoluble fraction of the 70% EtOH extract of roots of Sophora flavescens, showed dominant neuroprotective effects on glutamate-induced neurotoxicity in mouse hippocampal HT22 cells by induced the expression of HO-1 and increased HO activity. In mouse hippocampal HT22 cells, NNMBS008 makes the nuclear accumulation of Nrf2 pathway. In conclusion, the waterinsoluble fraction of the 70% EtOH extract of roots of S. flavescens (NNMBS008) significantly protect glutamate-induced oxidative damage by induction of HO-1 via Nrf2 pathway in mouse hippocampal HT22 cells. These results suggest that these extracts could be the effective candidates for the treatment of ROS-related neurological diseases.

• Biomolecules & Therapeutics
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• v.7 no.4
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• pp.362-370
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• 1999

Propolis, a natural resinous compound collected from honey bees, contains many biochemical constituents(wax, flavonoids, phenolic compounds, etc.) and has been used in traditional medicines as early as 300 B.C. It was been demonstrated that ethanol, acetylsalicylic acid, ischemia reperfusion, non-steroidal antiin-flammatory drugs and stress induce gastric lesions by promoting the generation of reactive oxygen metabolites. Therefore, some drugs that are capable of scavenging or inhibiting the generation of reactive oxygen radicals might be expected to prevent the gastric mucosal injury. The aim of this study was 1) to examine the antiulcer effect of propolis, 2) to investigate the mechanism of action by determining gastric acid secretion, lipid per-oxidation, mucus content and proton pump ($H^+$/$K^+$-ATPase) activity on gastric mucus in varios experimental models, and finally, 3) to isolate and identify the pure compounds that exert antiulcer activity. Step 2-1 and 2-3 sub-sub fraction shoed a significant reduction of severity of gastirc damage at the dose of 25 mg/kg in various experimental models. We isolated 4 sub-sub-sub fractions by flash column chromatography of Step 2-1 sub-sub fraction and one sub-sub-sub fraction by recrystalization of Step 2-3 sub-sub fraction. The protective effects of propolis sub-sub-sub fraction manifested sifnificant effects in HCl-ethanol induced gastric erosion model and aspirin induced gastric ulcer model. These results showed that the gastric mucosal protective effect of propolis might result from the increase of mucus secretion, free radical scavenging effect as well as the reduction of acid secretion in accordance with the reduction of $H^+$/$K^+$-ATPase activitv. Three compounds were isolated and identified from sub-sub fraction of propolis which showed antiulcer effects. Subsequently, these compounds were identified as a flavonoid, namely, 2-acetoxy-5,7,-dihydroxy-flavanone, galangin and chrysin.

• Journal of Nutrition and Health
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• v.33 no.7
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• pp.703-711
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• 2000

The purpose of this study was to investigate the effect of butanol(BuOH) fraction of Polygonatum odoratum with selenium tr-eatment on blood glucose levels and lipid peroxidations in streptozotocin(STZ) induced diabetric rats. Male Sprague-Dawly rats weighing(180-200g) were divided into five groups : normal STZ-control and three expreimental groups(P, odoratum group P, odo-Se group and Se group) Diabetes mellitus was induced by injection STZ in the tail vein at the dose of 45mg/kg B.W The BuOH fraction of Polygonatum odoratum(500mg/kg. B,W) given orally administered for 14 days. The Se treated group were fed a AIN-76 recommendation diet mixed with Na2Seo3(2mg/kg diet). Diabetic rats showed the lower weight gain compared to the normal rats. the plasma glucose levels of the P. odo-Se group were significantly lower than the other experimental groups. The plasma cholesterol levels were higher in STZ-control and Se groups compared toP.odoratum and P. odo-Se groups and HDL-cholesterol levels were increased in the diabetic experimental groups fed on BuOH fraction of P. odoratum with Se supplementation. The liver and muscle glycogen levels were not significantly differ among all groups. The plasma free fatty acid levels were lower in diabetic experimental groups fed on BuOh fraction of P. odoratum or Se sup-plementation than STZ-control and Se groups. Diabetics rats showed the higher levels of triglyceride in plasma andlower levels in liver compared with the normal group. Supplementation with Se decreased significantly the liver triglyceride level. The MDA levels in liver and kidney were significantly reduced in all the experimental groups. In conclusion administration of BuOH fraction of Polygonatuum odoratum with selenium supplementation reduced blood glucose levels and peroxdative tissue damage in STZ induced diabetic rats showing the possibility of preventiave and therapeutic use of the wild edible plant to the diabetes mellitus.

• Food Science of Animal Resources
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• v.35 no.1
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• pp.58-70
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• 2015

This study was conducted to examine the effect of egg shell membrane hydrolysates (ESMH) on wrinkle, UV, and moisture protection for cosmetic use. ESMH were fragmented as whole ESMH (before fractioning), Fraction I (> 10 kDa), Fraction II (3-10 kDa), and Fraction III (< 3 kDa). In order to test whether fractionated ESMH can be used for functional cosmetic materials, we examined not only the level of hyaluronic acid and collagen production, but also the MMP-1 activity using a HaCaT and CCD-986Sk cell line. Our study treated each sample of fractionated ESMH with different concentrations (0.01, 0.1, 1 mg/mL). In our in vivo research, we used hairless mice that had been exposed to UV-B to induce wrinkles for 7 wk, then applied Fraction I to the treatment group for 5 wk and then tested skin thickness, minimum erythema dose and moisture content. In addition, Fraction I was high in collagen and HA biosynthesis and it was better than TGF-${\beta}$ in improving of the skin. When TNF-${\alpha}$ caused MMP-1 activity in the CCD-986Sk cells, the whole ESMH and Fraction I proved to be effective in hindering the induction of collagenase depending on the concentration, and also showed outstanding effects in the suppression of skin aging. We found that the treatment group mice's UV-B radiation-induced skin damage was largely mitigated compared to that of the non-treatment group mice. Thus, we have concluded that EMSH helps to mitigate UV-B radiation-induced wrinkles, collagen, HA, MMP-1 activity and can be used for functional cosmetic materials.