• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.11
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• pp.936-941
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• 2007

This paper is on the influence of gas explosion caused by Vapor Cloud Explosion(VCE). Also, it is to understand the influence of the booth for explosion experiment which is installed to let the trainees for legal education which is managed by IGTT(Institute or Gas Technology Training) know the riskiness of explosion. In this study, the influence of explosion shock wave caused by VCE in enclosure was calculated by using the Hopkinson's scaling law and the accident damage was estimated by applying the influence on the adjacent human into the probit model. As a result of the damage estimation conducted by using the probit model, both the damage possibility of explosion overpressure to human 8 meters away and that of shock wave to hurt 15 meters away showed nothing.

• Polymer(Korea)
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• v.27 no.3
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• pp.210-216
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• 2003

4-Vinyl-1-cyclohexene diepoxide (VCE)/diglycidyl ether of bisphenol-A (DGEBA) epoxy blends with benzylquinoxalinium hexafluoroanti-monate were cured using an electron-beam technique. The effect of DGEBA content to VCE on cure behavior, thermal stabilities, and mechanical properties was investigated. The composition of VCE/DGEBA blend system vaned within 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100 wt%. The cure behavior and thermal stability of the cured specimens was monited by near-infrared spectroscopy and thermogravimetric analysis, respectively. Also, the critical stress intensity factor ($_{4}$) test of the cured specimens was performed to study the mechanical interfacial properties. As a result, the decreases of short side-chain structure and chain scission were observed in NIR measurements as the DGEBA content increases, resulting in varying the hydroxyl and carbonyl groups. And, the initial decomposition temperature (IDT), temperature of maximum weight loss (T$\_$max/), and decomposition activation energy (E$\_$d/) as thermal stability factors were increased with increasing the DGEBA content. These results could be explained by mean of decreasing viscosity, stable aromatic ring structure, and grafted interpenetrating polymer network with increasing of DGEBA content. Also, the maximum $_{4}$ value showed at mixing ratio of 40:60 wt% in this blend system. in this blend system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.100-106
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• 2003

This study was conducted to investigate the supplementary effects of vitamin C and E to moist pellet on growth and body composition in juvenile olive flounder (Paralichthys olivaceus). Four groups of diet made : moist pellet (MP) diet group was used as the control group where the ratio of raw feed and commercial compound meal is 5:5 $(CP\;30\%,\;CL\;17\%),$ vitamin C added group (VC), vitamin I added group (VE) and vitamin C and I added group (VCE). The supplementary amount of vitamin C and E corresponded to 1000 mg/kg (dry wt.) and 220mg/kg (dry wt.), respectively. Vitamin C was destroyed $50\%$ and vitamin E was destroyed $20\%$ for manufacturing process. After 8 weeks feeding trial, weight gain was $121.9\%$ in MP group, while it ranged from 180.5 to $184.9\%$ in the VC, VE and VCE group. Feed efficiency was $71.\6%$ in MP group, whereas it ranged from 78.7 to $80.6\%$ in the VC, VE and VCE group, weight gain and feed efficiency of fish fed vitamin supplemented diets were significantly higher than control group and no significant difference among the vitamin added groups was observed (p>0.05). There were no significant differences in moisture, crude protein, crude lipid, crude ash, condition factor (CF), hepatosomatic index (HSI), and visceraweight index (VWI) of body composition. Hemoglobin (Hb) was $3.79\%$ in MP group, whereas $4.99\%$ in VC group, $4.55\%$ in VE group and $5.07\%$ in VCE group; Hb was significantly higher in the vitamin added groups than the control group (p<0.05). Vitamin C retention in liver was 18.1, 20.7, 46.6, 54.0 mg/kg in MP, VE, VC and VCE groups, respectively. Vitamin E retention in liver was 25.9, 53.8, 88.2, 124.5 mg/kg in MP, VC, VE and VCE groups, respectively. These results indicate that supplementation of vitamin C and E to moist pellet diet significantly improved growth and feed efficiency of olive flounder, and the mixed addition of vitamin C (1,000 mg/kg dry wt.) and vitamin E (220 mg/kg dry wt.) did not lead to the synergy effect.

• Korean Journal of Food Science and Technology
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• v.47 no.2
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• pp.261-266
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• 2015

To quantitatively evaluate the total phenolics, total flavonoids, and antioxidant capacity in the leaves, bulbs, and roots of fresh Allium hookeri, they were extracted using various solvents including water, aqueous methanol (20, 40, 60, and 80%; v/v), and absolute methanol. The leaves had the highest levels of total phenolics (240.4-276.6 mg gallic acid equivalents/100 g) and total flavonoids (9.7-34.1 mg catechin equivalents/100 g). The highest antioxidant capacities of 78.7- 103.4 mg vitamin C equivalents (VCE)/100 g, 24.4-59.0 mg VCE/100 g, and 1,798.8-2,169.7 mg VCE/100 g in the leaves were also observed using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and oxygen radical absorbance capacity (ORAC) assays, respectively. The total phenolics had a higher linear correlation with antioxidant capacity than the total flavonoids. In general, 60% (v/v) aqueous methanol extract had higher levels of total phenolics and flavonoids, and higher antioxidant capacity than any other solvents used. This study suggested that A. hookeri might be a good source of phenolics and antioxidants.

• Journal of Microbiology and Biotechnology
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• v.30 no.3
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• pp.359-367
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• 2020

Neurodegenerative disorders in the elderly are characterized by gradual loss of memory and cognitive function. Oxidative stress caused by reactive oxygen species is associated with progressive neuronal cell damage and death in Alzheimer's disease, one of the most common neurodegenerative disorders. An edible brown seaweed, Ecklonia cava, contains a variety of biologically active compounds such as phlorotannins. In this study, we comparatively evaluated the total phenolic content, antioxidant capacity, and neuroprotective effects of the phlorotannin-rich extract from E. cava (PEEC). The total phenolic content of PEEC and dieckol was 810.8 mg gallic acid equivalents (GAE)/g and 996.6 mg GAE/g, respectively. Antioxidant capacity of PEEC was 1,233.8 mg vitamin C equivalents (VCE)/g and 392.1 mg VCE/g determined using ABTS and DPPH assays, respectively, while those of dieckol were 2,238.4 mg VCE/g and 817.7 mg VCE/g. High-performance liquid chromatography results revealed 48.08 ± 0.67 mg dieckol/g of PEEC. PEEC had neuroprotective effects in pheochromocytoma (PC-12) and human neuroblastoma (SH-SY5Y) cells against H₂O₂- and AAPH-induced oxidative damage, partly due to reduced intracellular oxidative stress. PEEC treatment inhibited acetylcholinesterase and butyrylcholinesterase in a dose-dependent manner. Taken together, these findings suggest that PEEC is a good source of antioxidants and neuroprotective materials.

• Horticultural Science & Technology
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• v.29 no.4
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• pp.358-365
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• 2011

Lespedeza cuneata G. Don is a plant commonly grown in Asian countries, which has been widely used as an oriental medicinal herb to treat diabetes, diarrhea and various other inflammatory diseases. The phenolics of dry leaves of L. cuneata G. Don were extracted by using 80% (v/v) aqueous methanol in assistance with homogenization and sonification. The phenolic extract and its five different fractions (n-hexane, chloroform, ethyl acetate, n-butanol, and water) were used to evaluate the levels of total phenolics, total flavonoids, and antioxidant capacity as well as the inhibitory effect of tyrosinase activity. Ethyl acetate fraction (1 g) had the highest levels of total phenolics at 240.8 mg gallic acid equivalents (GAE), total flavonoids as 90.4 mg catechin equivalents (CE) as well as antioxidant capacity at 523.4 mg vitamin C equivalents (VCE) on ABTS assay and 329.5 mg VCE on DPPH assay among fractions. One g of water fraction contained total phenolics at 133.1 mg GAE, total flavonoids at 34.5 mg CE, and antioxidant capacity at 333.4 mg VCE for ABTS assay and 313.2 mg VCE for DPPH assay. Inhibition of tyrosinase activity of water fraction at 300 ${\mu}g{\cdot}mL^{-1}$ was at 47.2% and 21.1% for L-tyrosine and L-DOPA as its substrate, respectively. On the other hand, ethyl acetate fraction at 300 ${\mu}g{\cdot}mL^{-1}$ showed tyrosinase inhibition of 10.2% for L-tyrosine and 11.9% for L-DOPA. These results suggested that the phenolics from dry leaves of L. cuneata G. Don may be utilized as a potent source of antioxidants and skin whitening agents.

• Fibers and Polymers
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• v.3 no.1
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• pp.14-17
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• 2002

Development of a novel fixed site carrier membrane (FCM), supported by PET fabric for metal ion separation is reported. The membranes were prepared by dipping PET fabric into the methylene chloride solution of Poly(5-vinyl-m-phe-nylene-m'-phenylene-32-crown-10) (P(VCE)), a polymeric metal ion carrier. It was found that the flux of mono-valent metal ion transported across the membrane is signif=cantly differed from each other and the flux decreases in the order $Cs^+$>$Rb^+$>$K^+$>$Na^+$>$Li^+$ irrespective to the anion except perchlorate anion. It was explained in terms of the stability of the complex, formed by crown ether unit of the P(VCE) and the various metal ions, meanwhile, the lower rate of transport in the presence of perchlorate anion was ascribed to its low hydrophilicity.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1315-1316
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• 2007

This is paper, a new structure to effectively improve the Vce(sat) voltage and latch-up current in NPT type IGBTs with hole barrier layer and diverter. The hole barrier layer acts as a barrier to prevent the holes from flowing into the p-layer and stores them in the n-layer. And the diverter significantly reduce hole current from flowing into the p-layer and improve latch up current. Analysis on the Breakdown voltage shows identical values compared to existing Conventional IGBT structures. This shows an improvement on Vce(sat) and Latct-up current without lowering other characteristics of the device. The electrical characteristics were studied by MEDICI simulation results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.11
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• pp.1091-1097
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• 2013

This paper presents a rectifier with comparator using unbalanced body biasing in $0.11{\mu}m$ RF CMOS process. It is composed of MOSFETs and two comparators. The comparator is used to reduce reverse leakage current which occurs when the load voltage is higher than input voltage. For the comparator, unbalanced body biasing is devised. By using unbalanced body biasing, reference voltage for comparator changing from high state to low state is increased, and it reduces time interval for leakage current to flow. 13.56 MHz 2 Vpp signal is used for input and $1k{\Omega}$ resistor and 1 nF capacitor are used for output load for simulation and experimental environment. In simulation environment, voltage conversion efficiency(VCE) is 87.5 % and Power conversion efficiency(PCE) is 50 %. When the rectifier is measured, VCE shows 90.203 % and PCE shows 45 %.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.58-65
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• 2012

Various models are currently applied to predict the dispersion of leaked combustible gas and overpressure from a vapor cloud explosion(VCE). However, those models use simple approaches where topography and barriers of anti-leakage facilities and the effects of buildings were not sufficiently taken into considerations. For this reason, this study has proposed the dispersion process of leaked gas, distribution patterns, and flames and overpressure generated from gas explosions in 2D and 3D virtual spaces by reviewing more accurately analyzable computational fluid dynamics (CFD) model by considering various variables including combustion types of leaked substances, geometry of facility, warm currents, barriers, the influence of wind, and others. The CFD analysis results are anticipated to be usefully applied for the risk analysis of explosion and for the risk-based design.