• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.418-426
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• 2015

Total phenol contents, total flavonoid contents and antioxidant activity of 70% methanol, 70% ethanol and chloroform-methanol (CM, 2:1, v/v) extracts from onion (Allium cepa L.) peels were studied. The $IC_{50}$ values of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical and ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] radical scavenging activity in 70% ethanol extract were remained to be lowest followed by 70% methanol extract and CM extract. And the total phenol content ($113.56{\pm}0.86mg\;CAE/g$), total flavonoid content (49.63 mg QE/g) and ferric reducing antioxidant power value were also found to be the highest. In contrast, 70% methanol extract possessed the strongest antioxidant activity by ${\beta}$-carotene bleaching assay. CM extract displayed the lowest antioxidant activity compared with other extracts. Onion peels exhibited strong antioxidant activity and abundant phytochemicals, which could be used in a various food products to add phytochemicals and promote good health.

• Korean journal of food and cookery science
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• v.25 no.4
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• pp.496-505
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• 2009

The influence of roasting time on antibacterial and antioxidative effects of methanol and water coffee extracts was investigated. Extract yield differed with roasting time. The maximum yield of methanol extract was 20.02% and 24.00% at respective roasting times of 12 and 20 min. The maximum yield of water extracts was 2.70% and 18.58% at 5 and 25 min roasting time, respectively. Antibacterial effects of each extract were determined by the classical minimal inhibitory concentration (MIC) paper disc diffusion method. Methanol extracts of different coffee samples inhibited growth of various strains except Escherichia coli. Extracts obtained following roasting times of 12, 14, 16, 20, and 25 min in particular displayed the most potent activity against Staphylococcus aureus. Among these extracts, that obtained from 12 min roasted coffee samples produced a MIC of $16.125{\mu}g$/mL against S. aureus. Water extracts applied at $1,000{\mu}g$/mL were growth inhibitory except against Salmonella choleraesuis and Prevotella intermedia. However, growth inhibition by water extracts was weak, with inhibitory zones of only 6-8 mm diameter produced. Determinations of free radical elimination for the different coffee extracts using 1,1-diphenyl-2-picrylhydrazyl were compared with ascorbic acid and butylated hydroxytoluene positive controls. Methanol and water extracts of different coffee samples ($100{\mu}g$/mL) showed $67.1{\sim}92.3%$ and $66.4{\sim}93.3%$ radical scavenging activity, respectively. However, longer roasting time (especially >20 min) tended to somewhat lower free radical elimination using both extracts. Total phenol in different coffee samples measured by the Folin-Denis method revealed the highest level of phenol contents with non-roasted coffee, whereas phenol content differed with different roasting time, ranging from $87.{\sim}126.5\;mg/g$ in methanol extracts. In water extracts, the phenol content was maximum at 8 min roasting time, whereas in other samples the content was varied from $95.0{\sim}199.1\;mg/g$.

• Journal of the Korean Wood Science and Technology
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• v.31 no.5
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• pp.15-22
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• 2003

This study was carried out to investigate the properties of sawdust board impregnated with phenol resin according to the density and resin content of board. The sawdust board were manufactured to target densities of 0.4, 0.5, 0.6, 0.7 g/cm³ and resin content of 5, 10, 15, 20% made from Pinus densiflora S. et Z., Larix. kaemferi C. and Pinus koraiensis S. et Z. The impregnation process were executed in two ways, the application of vacuum pressure then followed by atmospheric pressure, and the application of vacuum pressure with ultrasonic vibration then followed by atmospheric pressure. The density of impregnated sawdust board increased as density and resin content of sawdust board increased, but impregnation rate decreased. The density, impregnation rate, bending strength and brinell hardness of sawdust board in impregnated vacuum pressure with ultrasonic vibration then nonpressure were higher than those of vacuum pressure then nonpressure. In this results, the impregnation rate is increased in vacuum pressure with ultrasonic vibration then nonpressure, it has affected the properties of sawdust board impregnated with phenol resin.

• Journal of Korean Society of Forest Science
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• v.60 no.1
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• pp.51-57
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• 1983

Properties and glue shear strength of each water soluble rues-phenol copolymer adhesive and phenolic resin adhesive were examined as a high temperature curing binder through the manufacture of plywood made of Kapur veneer. The former has different molar ratio and the latter was made from different catalyst method. The results are summarized as follows: 1) Specific gravities of air dried plywood manufactured from each adhesive ranged from 0.67 to 0.82 and their moisture contents met the K.S. standard 2) In dry and wet shear strength, adhesives with 60 percent of non volatile content showed higher values than those with 50 percent except phenolic resin. Urea-phenol copolymer resin with 20 percent of phenol content exhibited the highest, and that with 70 percent the lowest. Filling effect of wood flour on the bonding strength is great in urea-phenol copolymer resin with more than 50 percent of phenol content, especially significant in 50 percent of non volatile content including alkali catalyst phenolic resin. Alkali and acid catalyst methods were the highest among the adhesive manufacture methods. In wet strength, urea resin belongs to the lowest group. 3) In glue shear strength after boiling and drying test, no method for manufacturing phenolic formaldehyde resin adhesive was stronger than alkali and acid catalyst methods. Phenolic resin made from alkali catalyst method needs a wood flour filler to improve the bonding quality. Urea-phenol copolymer resin with 10 percent of phenol content showed the reasonable water resistance.

• Journal of Soil and Groundwater Environment
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• v.28 no.1
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• pp.15-24
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• 2023

A persulfate(PS)/sulfidated microscale zero-valent iron(S-mZVI) system was tested for treating a soil contaminated with phenol. Sulfidation of bare mZVI was conducted using a mechanochemical process utilizing a ball mill in order to improve persulfate activation capacity and stability of unmodified mZVI. The synthesized S-mZVI performed markedly better than the bare mZVI in activating PS. The optimum molar ratio of sulfur to mZVI was around 0.12. In the soil slurry experiments, a very rapid and complete removal of phenol was observed at the optimum molar ratios of PS to S-mZVI of 2:1 and PS to phenol of 16:1. The phenol removal efficiencies decreased as the water content of the slurries decreased. This was believed to be due to increased soil oxidant demand as the amount of soil was increased as relative to the water content. To evaluate the field applicability of the process, slurry experiments adopting high soil contents were carried out that simulated in-situ soil mixing conditions. These experiments resulted in substantially compromised degradation efficiencies of 54.3% and 43.8% within 4 hours. The current study generally shows that the PS/S-mZVI process has a potential to be developed into a remediation technology for soils contaminated with organics.

• Composites Research
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• v.35 no.4
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• pp.288-297
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• 2022

This study investigated the effect of addition of zirconia(zirconium oxide) powder on the curing behavior of phenolic resins. The heating rate controlled curing and isothermal curing behaviors of the phenol resin according to the content of the zirconia powder were analyzed. The viscosity and thermal decomposition characteristics of the phenolic resin with the zirconia content were also examind. From the DSC analysis, the degree of cure and the rate of cure were obtained. Finally, the activation energy for the cure reaction were calculated from the DSC data of the zirconia added phenolic resin. As a found, the higher the zirconia content, the longer the curing was delayed and the greater the activation energy required for curing. Additionally, the TGA result that as the content of zirconia increased, less weight loss was observed. The surface tackiness of the Carbon/Phenol prepreg was partially changed according to the zirconia content, but had no significant effect.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.797-806
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• 2000

The objectives were to compare the biodegradable threshold concentrations of phenol with the different composition of the influent carbon source and examine the SMA (Specific Methanogenic Activity)and the possibility of simultaneous removal of high-strength organics and nitrogen compounds in UASB(Upflow Anaerobic Sludge Blanket) - PBR(Packed Bed Reactor) process. The results showed that UASB reactors were efficient to remove phenol and phenol + glucose from synthetic wastewater. At phenol conc, of 600 mg/L and SCOD conc. of 2100 mg/L in UASB reactor(with only phenol as substrate), the removal efficiencies of phenol and SCOD were over 99% and 93% respectively, under MLVSS of 20 g. The activity of microorganism was $0.112g\;phenol/g\;VSS{\cdot}d$, $0.351g\;SCOD/g\;VSS{\cdot}d$. The gas production rate was $0.115L/g\;VSS{\cdot}d$ and $CH_4$ content in gas was about 70%. At phenol conc. of 760 mg/L and SCOD conc. of 4300 mg/L in UASB reactor( with phenol + glucose as substrates), the removal efficiencies of phenol and of SCOD were over 99% and 90% respectively, under MLVSS of 20 g. The activity of microoganism was $0.135g\;phenol/g\;VSS{\cdot}d$, $0.696g\;SCOD/g\;VSS{\cdot}d$. The gas production rate was $0.257L/g\;VSS{\cdot}d$ and $CH_4$ content in gas was about 70%. Serum bottle test showed that the activity of granule was inhibited over 1600 mg/L phenol conc, and denitrification and methanogenesis simultaneously took place in UASB granules under co-substrates conditions. PBR reactor packed with cilium type media, was efficient in nitrification. In condition of $0.038kg\;NH_4-N/m^3-media{\cdot}d$. 10~12 mg/L phenol conc. and 200~500 mg/L SCOD conc., nitrification efficiency was over 90% and phenol removal efficiency was over 98%.

• Journal of Korea Foresty Energy
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• v.24 no.1
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• pp.33-38
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• 2005

To find a new use of wood tar which is obtained from the manufacturing process of wood charcoal, a resol type of phenol adhesive using wood tar was made and some adhesion tests on plywood were examined. Phenol adhesive synthesized with pine tar was almost same as an original phenol adhesive in physical properties such as solid content and viscosity and tensile-shear adhesive strength of plywood made of phenol adhesive synthesized with pine tar was not much lower than the original one in non-waterproof and waterproof tests. Phenol adhesive synthesized with oak tar, however, was different from original phenol adhesive in physical properties. Adhesive strength of plywood made of oak tar was $50\%$ lower than the original one on waterproof tests. The amount of emitted formaldehyde increased as the amount of wood tar increased.

• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.619-630
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• 2012

Miscellaneous grain crops has been appeared as a well-being food and the demand of them are increasing recently. It is urgent to study especially about the functional materials of foxtail millet, common millet and sorghum. This experiment was conducted to evaluation and comparison several functional materials of fatty acids, anthocyanin content, total phenol content and DPPH assay of rice, and foxtail millet, common millet and sorghum produced organically so that these results would provide as a basic information for developing functional products by using miscellaneous grain crops. Total content of fatty acids was in order of foxtail millet (0.649%) and common millet (0.33%), sorghum (0.172%) and rice (0.111%) respectively. The content of unsaturated fatty acid was also in order of foxtail millet (0.511%) and common millet (0.269%), sorghum (0.122%) and rice (0.069%) respectively. Although there was no detection of anthocyanin content in rice, foxtail millet and common millet, sorghum showed high content of anthocyanin content. Sorghum of Mongdangsusu showed the highest anthocyanin content (137.5mg/g). In the total phenol content of rice, foxtail millet, common millet and sorghum, rice of Chucheongbyeo had high content ($13.70{\mu}g/g$) whereas Daeanbyeo was the lowest content ($10.07{\mu}g/g$). Foxtail millet of Hinchajo, common millet of Byeorukgijang and sorghum of Chalsusu showed the highest total phenol content of $25.8{\mu}g/g$, $69.4{\mu}g/g$ and $682.2{\mu}g/g$ respectively. In the average of total phenol content among rice, foxtail millet, common millet and sorghum, foxtail millet, common millet and sorghum showed $12.25{\mu}g/g$, $16.95{\mu}g/g$, $51.01{\mu}g/g$ and $447.4{\mu}g/g$ of total phenol content respectively. The average of total phenol content of sorghum was $26.3{\mu}g/g$. It is 36.3 and 26.3 times higher compared with rice and foxtail millet respectively. In the antioxidant activity of seeds by DPPH(1,1-diphenyl-2-picrylhydrazyl) assay for rice, foxtail millet, common millet and sorghum, rice of Chucheongbyeo, foxtail millet of Ganghywajo and common millet of Geumeungijang showed the highest antioxidant activity with 3.6%, 4.78% and 13.4% respectively. Antioxidant activity of sorghum ranged from 88.47 to 90.11%. The average of antioxidant activity among four crops, the highest antioxidant activity was obtained from sorghum (89.50%) and the next was common millet (6.13%), foxtail millet (2.43%), and rice (1.60%) in their order of antioxidant activity. The average of antioxidant activity of sorghum showed 55.9, 37.0 and 15times higher compared with rice, common millet and foxtail millet respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.8
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• pp.1151-1156
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• 2005

The comparison on antioxidative activity of 13 kinds of vegetables that showed efficient oxygen radical absorbance capacity was carried out under in uitro and cellular model using LLC-$ PK_{1}$ renal epithelial cell, and also the total Phenol contents were analyzed. Beets, eggplant, and kale exerted the strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect and also these vegetables showed high contents of total phenol, indicating the positive relationship between DPPH radical scavenging effect and total phenol content. In addition, the treatment of 1 mM 2,2'-azobis (2-amidinopropane) dihydrochloride for 24 hrs to LLC-$PK_{1}$ cell susceptible to oxidative stress led to the decline of cell viability to 68.1$\%$, whereas the cellular oxidative damage was ameliorated by vegetables, especially eggplant and cauliflower, resulting in the elevation of cell viability to higher than 90$\%$ at the concentration of 5 $\mu$g/mL. This study suggests that 13 kinds of vegetables exert antioxidative activity under in uitro and cellular oxidative damage model, in particular among them eggplant showed the most effective antioxidative activity with higher total phenol content.