• Macromolecular Research
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• v.12 no.4
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• pp.325-335
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• 2004

Molecular weight distributions of poly(vinyl neo-decanoate) produced by the bulk polymerization of the monomer to low conversions were investigated to obtain values of the rate constants for the chain transfer to monomer ( $C_{M}$). The value of $C_{M}$ of 7.5($\pm$0.6)${\times}$10$^{-4}$ was obtained from a logarithmic plot of the number distribution at 5,25, and 5$0^{\circ}C$, which suggests that the activation energy for chain transfer is on the order of 20-25 kJ ㏖$^{-1}$ . These plots were linear between the number and weight-average degrees of polymerization, but not over the whole molecular weight range for which a significant signal was observed in the gel permeation chromatography (GPC) trace. Modeling suggests that the deviations observed at high molecular weights can be explained by branching of the chains through chain transfer to the polymer, with a branching density as low as 10$^{-5}$ , without affecting the slope at low values of the number of monomer unit, N. This deviation from the expected distribution of linear chains was used to estimate the branching densities at low conversion.ion.

• Korean journal of food and cookery science
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• v.30 no.6
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• pp.679-686
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• 2014

This study was carried out to evaluate the quality characteristics of cookies added with various concentrations (0, 1, 3 and 5%) of ginseng leaf powder. The pH of the cookies significantly decreased with increased ginseng leaf powder concentrations (p<0.05), but the density of cookies showed no significant differences. Spread factor, loss rate, and leaving rate of cookies decreased according to the amount of added ginseng leaf powder. The lightness and yellowness of cookies decreased as the concentration of the ginseng leaf powder increased whereas no significant difference in the redness was found with increased ginseng leaf concentration. In the texture analysis, the hardness of the cookies increased according to the concentration of ginseng leaf. DPPH free radical scavenging activity of the cookies significantly increased with increased ginseng leaf concentration (p<0.05). In the sensory evaluation, sensory scores for color, taste and overall acceptability were highest in the 3% ginseng leaf cookies. Thus, our results suggested that the optimum amount of ginseng leaf powder to add to cookies was 3%.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.194-199
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• 2011

This study has been carried out to evaluate the performance of $PbO_2$ electrode for the purpose of degradation of N,N-Dimethyl-4-nitrosoaniline (RNO, indicator of OH radical), generation of ozone and decolorization of Rhodamine B (RhB) in water. The effect of the applied current (0.2~1.2 A), electrolyte type (NaCl, KCl and $Na_2SO_4$), electrolyte concentration (0.0~2.5 g/L) and solution pH (3~11) were evaluated. Experimental results showed that RhB and RNO removal were increased with the increase of current, NaCl dosage and decrease of pH. Ozone generation tendencies appeared with the almost similar to the RhB and RNO degradation, except of solution pH (Ozone generation was increased with increase of pH). Optimum current for RhB degradation and consumption of electric power was 1.0 A. The RhB degradation with Cl type electrolyte were higher than that with the sulfate type. Optimum NaCl dosage for RhB degradation was 1.0 g/L.

• Journal of Soil and Groundwater Environment
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• v.26 no.1
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• pp.45-53
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• 2021

The removal of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution by coupled electro-oxidation and Fe(II) activated persulfate oxidation process was investigated. The electrochemical oxidation was performed using carbon sheet electrode and persulfate using Fe(II) ion as an activator. The oxidation efficiency was investigated by varying current density (2 - 10 mA/㎠), electrolyte (Na2SO4) concentration (10 - 100 mM), persulfate concentration (5 - 20 mM), and Fe(II) concentration (10 - 20 mM). The 2,4-D removal efficiency was in the order of Fe(II) activated persulfate-assisted electrochemical oxidation (Fe(II)/PS/ECO, 91%) > persulfate-electrochemical oxidation (PS/ECO, 51%) > electro-oxidation (EO, 36%). The persulfate can be activated by electron transfer in PS/ECO system, however, the addition of Fe(II) as an activator enhanced 2,4-D degradation in the Fe(II)/PS/ECO system. The 2,4-D removal efficiency was not affected by the initial pHs (3 - 9). The presence of anions (Cl- and HCO3-) inhibited the 2,4-D removal in Fe(II)/PS/ECO system due to scavenging of sulfate radical. Scavenger experiment using tert-butyl alcohol (TBA) and methanol (MeOH) confirmed that although both sulfate (SO4•-) and hydroxyl (•OH) radicals existed in Fe(II)/PS/ECO system, hydroxyl radical (SO4•-) was the predominant radical.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.10
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• pp.1414-1421
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• 2009

Pine needle powder has medical and functional uses. In this study, cookies were prepared using different 0.5%, 1%, 3%, 5% of pine needle powder. The total phenolic content was measured by the Folin-Ciocalteu method, and antioxidant activity was evaluated by DPPH assay. The antioxidant activity was highly correlated with the total phenolic composition of pine needle cookies (r=0.989). In addition, the quality characteristics of the pine needle cookies were estimated based on the bulk density and pH of the dough, spread factor, loss rate, leavening rate, color, texture profile analysis, and sensory evaluations. The bulk density of the dough and the hardness, total polyphenol contents and DPPH free radical scavenging activity of cookies significantly increased with increasing pine needle powder, while the pH of the dough, spread factor and L values of the cookies decreased with increasing pine needle powder content (p<0.05). Additionally, the consumer acceptability scores for the 3% pine needle cookie groups ranked significantly (p<0.05) higher than those of the other groups in appearance, taste, flavor, texture and overall preference. Taken together, the results of this study suggest that pine needle powder is a good ingredient for increasing the consumer acceptability and the functionality of cookies.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.11
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• pp.1792-1798
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• 2013

Cedrela sinensis is a Korean traditional wild herb that has a special taste and aroma. This study is conducted to investigate the effect of Cedrela sinensis powder on the antioxidant activity and the quality characteristics of Maejakgwa (Korean traditional cookie). Maejakgwa was prepared with different amounts of Cedrela sinensis powder (in ratios of 0, 5, 10, 15 and 20% to the flour quantity). The antioxidant activity was estimated by DPPH free radical scavenging activity and the total phenol content in Cedrela sinensis powder and Maejakgwa. For analyzing the quality characteristics, the bulk density and pH of the dough, moisture contents, volume, color, texture profile analysis, and sensory evaluations were measured. The bulk density, moisture contents, volume, total phenol contents and DPPH free radical scavenging activity of Maejakgwa significantly increased with increasing Cedrela sinensis powder (P<0.001), while the pH of the dough, L values and b values of Maejakgwa significantly decreased with increasing Cedrela sinensis powder content (P<0.001). The consumer acceptability score for 10% Cedrela sinensis Maejakgwa ranked significantly higher (P<0.001) than those of the other groups in overall preference, flavor, taste, crispiness and color. From these results, we suggest that Cedrela sinensis is a good ingredient for increasing the consumer acceptability and functionality of Maejakgwa.

• Journal of Life Science
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• v.26 no.12
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• pp.1415-1421
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• 2016

This study was worked to investigate the antioxidant activity and the blood circulation improvement effect of two Hibiscus syriacus extracts divided into fermented H. syriacus extract and non-fermented H. syriacus extract. As the results of in vitro experiment, both of fermented H. syriacus extract and non-fermented H. syriacus extract had the DPPH free radical scavenging effect and the high contents of polyphenol and flavonoid known as antioxidant components in dose-dependent manner. Six weeks female C57BL/6 mice were divide into four groups and fed high diets for 28 days. Also fermented H. syriacus extract and non-fermented H. syriacus extract was daily intraperitoneal administration for 28 days at 2 mg/kg of body weight of mice. In vivo C57BL/6 mice experiment of normal diet group (NOR), high-fat diet group (CON), high-fat diet plus fermented H. syriacus extract group (FHS) and high-fat diet plus non-fermented H. syriacus extract group (NFHS), each of total cholesterol, triglyceride and low density lipoprotein (LDL) was decreased in both of FHS and NFHS groups, meanwhile high density lipoprotein (HDL) was increased (p<0.01). Conclusion, the results confirmed that H. syriacus containing the high contents of the antioxidant activity components had the significant effects of blood circulation improvement.

• Korean Journal of Medicinal Crop Science
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• v.12 no.1
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• pp.79-84
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• 2004

To develop a new functional materials, angiotensin converting enzyme (ACE) inhibitory activity, antioxidant effect and total phenolic content of Hovenia dulcis Thunb. cortex were evaluated. Methanol and water extract of H. dulcis inhibited ACE by 81% and 76%, respectively, at the concentration of $4,000\;{\mu}g\;m{\ell}^{-1}$ which were similar level with that (85%) of commercial peptide-type ACE inhibitor. Superoxide radical scavenging activity of two extracts $(99.5%{\sim}99.9%)$ were stronger than that (69%) of ascorbic acid at the final concentration of $200\;{\mu}g\;m{\ell}^{-1}$. Among the solvent fractions, ether and ethylacetate fraction showed also potent scavenging activities (91% and 85%) for superoxide radical. Inhibitory activities of two extracts on oxidation of human low density lipoprotein (LDL) which were similar with that of ${\alpha}-tocopherol$, were higher than 80% at the concentration of $50\;{\mu}g\;m{\ell}^{-1}$. Total phenol contents of methanol and water extracts were 7.2% and 3.6%, respectively, and that of ethylacetate showed the highest value as 60.8% among the solvent fractions. Therefore, it has been suggested that H. dulcis cortex could be a effective anti-hypertention and antioxidant resource to develope a new functional material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.363-363
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• 2008

The development of dry etching process for sapphire wafer with plasma has been key issues for the opto-electric devices. The challenges are increasing control and obtaining low plasma induced-damage because an unwanted scattering of radiation is caused by the spatial disorder of pattern and variation of surface roughness. The plasma-induced damages during plasma etching process can be classified as impurity contamination of residual etch products or bonding disruption in lattice due to charged particle bombardment. Therefor, fine pattern technology with low damaged etching process and high etch rate are urgently needed. Until now, there are a lot of reports on the etching of sapphire wafer with using $Cl_2$/Ar, $BCl_3$/Ar, HBr/Ar and so on [1]. However, the etch behavior of sapphire wafer have investigated with variation of only one parameter while other parameters are fixed. In this study, we investigated the effect of pressure and other parameters on the etch rate and the selectivity. We selected $BCl_3$ as an etch ant because $BCl_3$ plasmas are widely used in etching process of oxide materials. In plasma, the $BCl_3$ molecule can be dissociated into B radical, $B^+$ ion, Cl radical and $Cl^+$ ion. However, the $BCl_3$ molecule can be dissociated into B radical or $B^+$ ion easier than Cl radical or $Cl^+$ ion. First, we evaluated the etch behaviors of sapphire wafer in $BCl_3$/additive gases (Ar, $N_2,Cl_2$) gases. The behavior of etch rate of sapphire substrate was monitored as a function of additive gas ratio to $BCl_3$ based plasma, total flow rate, r.f. power, d.c. bias under different pressures of 5 mTorr, 10 mTorr, 20 mTorr and 30 mTorr. The etch rates of sapphire wafer, $SiO_2$ and PR were measured with using alpha step surface profiler. In order to understand the changes of radicals, volume density of Cl, B radical and BCl molecule were investigated with optical emission spectroscopy (OES). The chemical states of $Al_2O_3$ thin films were studied with energy dispersive X-ray (EDX) and depth profile anlysis of auger electron spectroscopy (AES). The enhancement of sapphire substrate can be explained by the reactive ion etching mechanism with the competition of the formation of volatile $AlCl_3$, $Al_2Cl_6$ or $BOCl_3$ and the sputter effect by energetic ions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.6
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• pp.941-945
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• 2004

To increase utilities as functional materials, nine peanut varieties were evaluated on antioxidant activity and total phenol content. Peanut varieties were individually divided into three parts such as part without seed coat, seed coat, and seed. Each of the 80% ethanol-extracted solutions from the parts was used for the assay. Inhibitory activities on low density lipoprotein (LDL) oxidation by the part without seed coat, seed coat, and seeds from 9 varieties were respectively 85.3∼91.0%, 77.4∼85.8%, -1.7∼46.1%, and those on linoleic acid oxidation were 94.0∼94.9%, 94.2∼95.0%, 69.4∼80.2%, respectively. Seed coats, parts without seed coat, and seeds from 9 peanut varieties showed scavenging activities as 88.3∼98.7%, 16.7∼56.3%, -28.0∼20.0% on superoxide anion radical and as 89.9∼90.8%, 6.0∼12.0%, 0.6∼2.1% on 1,1-diphenylpicrylhydrazyl (DPPH) radical, respectively. Total phenol contents of seed coat, seed, and part without seed coat were 12.7∼21.0 mg%, 2.46∼4.24 mg%, 0.94∼1.16 mg% as tannic acid equivalent and those of Daekwang, Daesin, Bowon, Saedl, Kipung among the peanut varieties were comparatively high. In conclusion, Daekwang, Daesin, Kipung, and Saedl among the peanut varieties showed comparatively effective antioxidant activities.