• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.498-504
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• 2006

The etch rates of photoresist (PR) and the etch selectivity of $SiO_2$ to PR in a high density $CHF_3$ plasma were investigated at different ion-incident angles and bias voltages. A Faraday cage was employed for the accurate control of ion-incident angles. The ion energy was controlled by changing bias voltages. The etch rate of $SiO_2$ continuously decreased with ion-incident angles but the etch rate of PR remained constant up to the middle angle region and decreased afterwards. The etch rates of $SiO_2$ normalized to those at $0^{\circ}$ incident angle changed with the ion-incident angle following a cosine(${\theta}$) curve. On the other hand, the normalized etch rates of the PR changed showing a drastic over-cosine shape in the middle angle region. The etch selectivity of $SiO_2$ to PR decreased with an increase in the ion-incident angle because the etch yields of PR were enhanced by physical sputtering in the middle angle region compared to the case of $SiO_2$ etching. The etch selectivity of $SiO_2$ to PR decreased with an increase in the bias voltage at nearly all ion-incident angles.

• Toxicological Research
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• v.28 no.2
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• pp.73-79
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• 2012

While the ability to develop nanomaterials and incorporate them into products is advancing rapidly worldwide, understanding of the potential health safety effects of nanomaterials has proceeded at a much slower pace. Since 2008, Korea Food and Drug Administration (KFDA) started an investigation to prepare "Strategic Action Plan" to evaluate safety and nano risk management associated with foods, drugs, medical devices and cosmetics using nano-scale materials. Although there are some studies related to potential risk of nanomaterials, physical-chemical characterization of nanomaterials is not clear yet and these do not offer enough information due to their limitations. Their uncertainties make it impossible to determine whether nanomaterials are actually hazardous to human. According to the above mention, we have some problems to conduct the human exposure risk assessment currently. On the other hand, uncertainty about safety may lead to polarized public debate and to businesses unwillingness for further nanotechnology investigation. Therefore, the criteria and methods to assess possible adverse effects of nanomaterials have been vigorously taken into consideration by many international organizations: the World Health Organization, the Organization for Economic and Commercial Development and the European Commission. The object of this study was to develop risk assessment principles for safety management of future nanoproducts and also to identify areas of research to strengthen risk assessment for nanomaterials. The research roadmaps which were proposed in this study will be helpful to fill up the current gaps in knowledge relevant nano risk assessment.

• Journal of Soil and Groundwater Environment
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• v.19 no.1
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• pp.34-45
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• 2014

A variety of physical, chemical, and microbiological techniques have been developed to deal with soil and groundwater contamination. However, in the presence of the large portion of soil micro-environments, contaminant rebound and/or tailing have been frequently reported. Case study of total petroleum hydrocarbons (TPH) removal by full-scale land farming showed that contaminant rebound and/or tailing occurred in 9 out of total 21 cases and subsequently resulted in problems of a long term operation to satisfy TPH guidelines of contaminated soil and groundwater. The main cause of contaminant rebound and tailing is considered to be the strong interactions between contaminants and micro-environments including micro-particles, micro-pores, and organic matter. Thus, this study reviewed the effects of soil micro-environments of soil and groundwater on the removal efficiency for both heavy metals and petroleum contaminants. In addition, the various methods of sampling, analysis, and assessment of soil micro-environments were evaluated. Thorough understanding of the effects of soil micro-environments on contaminant removal will be essential to achieve a cost-effective and efficient solution to contaminated sites.

• Journal of Environmental Science International
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• v.20 no.2
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• pp.251-260
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• 2011

$TiO_2$- and $SiO_2$-supported $Co_3O_4$, Pt and $Co_3O_4$-Pt catalysts have been studied for CO and $C_3H_8$ oxidations at temperatures less than $250^{\circ}C$ which is a lower limit of light-off temperatures to oxidize them during emission test cycles of gasoline-fueled automotives with TWCs (three-way catalytic converters) consisting mainly of Pt, Pd and Rh. All the catalysts after appropriate activation such as calcination at $350^{\circ}C$ and reduction at $400^{\circ}C$ exhibited significant dependence on both their preparation techniques and supports upon CO oxidation at chosen temperatures. A Pt/$TiO_2$ catalyst prepared by using an ion-exchange method (IE) has much better activity for such CO oxidation because of smaller Pt nanoparticles, compared to a supported Pt obtained via an incipient wetness (IW). Supported $Co_3O_4$-only catalysts are very active for CO oxidation even at $100^{\circ}C$, but the use of $TiO_2$ as a support and the IW technique give the best performances. These effects on supports and preparation methods were indicated for $Co_3O_4$-Pt catalysts. Based on activity profiles of CO oxidation at $100^{\circ}C$ over a physical mixture of supported Pt and $Co_3O_4$ after activation under different conditions, and typical light-off temperatures of CO and unburned hydrocarbons in common TWCs as tested for $C_3H_8$ oxidation at $250^{\circ}C$ with a Pt-exchanged $SiO_2$ catalyst, this study may offer an useful approach to substitute $Co_3O_4$ for a part of platinum group metals, particularly Pt, thereby lowering the usage of the precious metals.

• Korean Journal of Food Science and Technology
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• v.23 no.4
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• pp.485-489
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• 1991

In order to study the effects of blanching and germination of soybean on the quality of soymilk, the soybeans were differently treated as follow; (1) blanched for 5 min at $100^{\circ}C$, (2) germinated for 2 days at $25^{\circ}C$, (3) germinated for 2 days and then blanched for 5 min at $100^{\circ}C$. The qualities of various soymilks prepared from the treated soybeans were compared with those of soymilk from the untreated soybeans. Blanching of soybeans decreased yields, solid materials, viscosity, total protein, soluble nitrogen, and total sugar of soymilk but no effect on its free sugar contents, specific gravity, and pH. The blanching, however, improved the sensory properties and decreased the n-hexanal contents of soymilk to about 1/2.4. Germination of soybeans improved the yields, physical, chemical, and sensory properties and decreased the n-hexanal contents of soymilk to about 1/5. The germination plus blanching of soybeans showed kind of combined effects of germination's and of blanching's, resulting in the decrease of n-hexanal to about 1/10 and improvement in sensory properties of soymilk.

• Journal of Life Science
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• v.25 no.8
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• pp.880-888
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• 2015

Foeniculum vulgare (FV) has long been used in traditional medicine for the treatment of inflammatory diseases. In addition, it is usually known as an important medicinal and aromatic plant widely used as a carminative, digestive, lactogogue, and diuretic, and for treating respiratory and gastrointestinal disorders. The skin barrier protects against the invasion of pathogens, fends off chemical and physical assaults, and protects against extensive water loss. In this study, the effects of solvent-fractionated FV fruits on strengthening the skin barrier and maintaining moisture, as well as their antifungal activity, were investigated in human keratinocyte (HaCaT) cells. The expression of involucrin, loricrin, filaggrin, hyaluronic acid synthase, human β defensin, and cathelicidin genes and proteins was measured by reverse transcription polymerase chain reaction (RT-PCR) and western blotting. The production of hyaluronic acid was determined by enzyme-linked immunosorbent assay (ELISA). The butanol fraction increased the expression of involucrin and filaggrin. Both the ethyl acetate and the butanol fractions increased hyaluronic acid production by promoting the expression of hyaluronic acid synthase-1. Although the antimicrobial peptides were increased by FV crude extract and its fractions, the samples did not show a significant effect compared to the normal group. These results suggest that the butanol fraction of FV could be very useful in cosmetics for the treatment of dermatological diseases.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.419-426
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• 1999

In this study, the reaction rate constant, activation energy, total crosslinking density, elastic constant, cure properties ($t_5,\;t_{90}$), modulus, and abrasion resistance of rubber compounds were investigated as a function of cure temperatures, cure systems and reinforcing filler loadings. Reaction rate constants showed strong dependence on thc carbon black loading, cure temperature and cure system, and increased sharply with increasing the reaction temperatures. The lowest activation energy was obtained in the efficient cure (EC) system which corresponds to the high level of sulfur to accelerator ratio, and the activation energy was decreased with decreasing the carbon black loadings. The change of carbon black loadings directly affects the modulus and abrasion resistance, but the change of cure system showed various effects on the rubber compounds. Increased carbon black loadings showed the high modulus, improved abrasion resistance and short scorch time but decrease in crosslinking density and elastic constant. Higher crosslinking density and elastic constant were shown in the EC cure system regardless of carbon black loadings, but scorch timc ($t_5$) was not affected by the change of the ratio of sulfur to accelerator. Rapid optimum cure time ($t_{90}$) were showen in the EC cure system. Also, the equivalent cure curve coefficient of rubber compound was 0.96 for conventional cure (CC) system, and 0.94 for semi-efficient cure (SEC) and EC system regardless carbon black loadings. As regarding the abrasion resistance, wear volume showed the logarithmic increase for the loaded weight.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.253-259
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• 2012

Disposal of high amount of coal combustion by-products, such as fly ash and bottom ash, is of a great concern to the country, due to the huge treatment cost and land requirement. On the other hand, those coal-ash wastes are considered to have desirable characteristics that may improve physical, chemical, and biological properties of soils. Especially, compared with fly ash, bottom ash has a larger particle size, porous surface area, and usable amount of micronutrients. In the present study, we examined bottom as a soil amendment for mitigating $CO_2$ emission and enhancing carbon sequestration in soils fertilized with organic matter (hairy vetch, green barely, and oil cake fertilizer). Through laboratory incubation, $CO_2$ released from the soil was quantitatively and periodically monitored with an enforced-aeration and high-temperature respirometer. We observed that amendment of bottom ash led to a marked reduction in $CO_2$ emission rate and cumulative amount of $CO_2$ released, which was generally proportional to the amount of bottom ash applied. We also found that the temporal patterns of $CO_2$ emission and C sequestration effects were partially dependent on the relative of proportion labile carbon and C/N ratio of the organic matter. Our results strongly suggest that amendment of bottom ash has potential benefits for fixing labile carbon as more stable soil organic matter, unless the bottom ash contains toxic levels of heavy metals or other contaminants.

• Journal of Practical Agriculture & Fisheries Research
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• v.7 no.1
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• pp.109-117
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• 2005

This study was carried out to determine effects of the feeding length of spent mushroom composts from selenium-enriched mushroom (Se-SMC) on meat quality and carcass characteristics in finishing Hanwoo steers. A total of 20 steers were used in this trial with four treatments. Treatments included control (no Se-SMC), Se-SMC groups of three different feeding lengths (2, 4, and 6 months). After the completion for each feeding length, steers were slaughtered and then loin muscle (Longissimus dorsi) was sampled to evaluate meat quality characteristics. Chemical compositions of the loin, except for protein content, were not different across treatments. Protein content was highest in 6 months feeding groups, however, it was lowest in 4 months. Physical property and meat color (L*, a* and b* values) were not affected by the feeding length of Se-SMC. However, water holding capacity (WHC) for Se-SMC feeding treatments was significantly more improved (p<0.05) in comparison with the control group, showing 63.8 (2 months), 64.4 (4 months), 64.2 (6 months), and 59.5% (control), respectively. Grades for meat quality and quantity, and carcass characteristics were not affected by feeding length of Se-SMC. Our results showed that Se-SMC supplementation was not significantly associated with parameters for meat quality and carcass characteristics. However, as feeding Se-SMC lengthens, WHC for loin was more improved, suggesting that the improved WC may result in the expression of antioxidant effect.

• Korean Journal of Organic Agriculture
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• v.32 no.1
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• pp.75-90
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• 2024

Biochar is a solid substance with a high carbon content, as it is made out of biomass pyrolyzed under the condition of limited oxygen. This product has attracted attention as an environment-friendly soil amendment because it contributes to carbon neutrally and has improvement effects on the soil environment. This study conducted an experiment to evaluate soil physiochemical properties and microbial community changes in a melon greenhouse according to the applied amount of biochar to investigate the growth characteristics and yields of melons accordingly. In soil physical properties, an increase in the applied amount of biochar resulted in a decrease in bulk density and an increase in porosity of the soil, improving air permeability. In soil chemical properties, an increase in the applied amount of biochar led to a increasing of pH, organic matter and available phosphate content. In the growth characteristics of melons, there was a growing tendency of plant height, leaf length and leaf width according to the increasing application of biochar until 10,000 kg/ha. Moreover, melon yields also increased as the amount of biochar, 13~16% higher in 10,000 kg/ha biochar application than no treatment. Compared differences among microbial communities in the soil according to the application of biochar and found that plant beneficial bacteria dominated in biochar treatments. This study demonstrated the potential of biochar as an effective soil amendment in melon greenhouse by showing improvements in soil physicochemical properties and microbial communities.