• Applied Biological Chemistry
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• v.44 no.2
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• pp.109-115
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• 2001

The foliar uptake of dimethomoiph induced by several nonionic surfactants was measured in order to study the correlations between the uptake rate of dimethomorph and the fungicidal activity to cucumber downy mildew. Dimethomorph was not absorbed in cucumber leaf in the absence of activator surfactant. And the curative effect of dimethomoiph WP to cucumber downy mildew was very low under the concentration of 250 ${\mu}g/ml$. But dimethomorph uptake was remarkably enhanced by addition of nonionic surfactants, such as polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, and polyoxyethylene stearyl ether. And the curative effect to cucumber downy mildew was enhanced with proportion to uptake rate of dimethomorph. The protective effect to cucumber downy mildew, however, tends to decrease with the increase of foliar uptake of dimethomorph. The uptake rate of dimethomorph to cucumber leaf was proportional to the content of polyoxyethylene cetyl ether in formulation, but was decreased with dilution.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.914-919
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• 1997

On the basis of theory of Bratsch's electronegativity equalization, the electronegativity equalization, the group electronegativities and the group partial charges for anionic and nonionic surfactants could be calculated by using Pauling's electronegativity parameters. From calculated results, we have investigated how CMC, hydrophilic and hydrophobic groups, group partial charge, electronegativity of hydrophilic and hydrophobic groups, structural stability of micelle for anionic and nonionic surfactants are related. It was fround that CMC depends upon group partial charge and group electronegativity of hydrophilic and hydrophobic groups of surfactants. For the anionic surfactants, negative partial charge in hydrophobic group is delocalized as the carbon number in hydrophobic group increase. So negative partial charge of hydrophilic group has very large electronegativity that is decreased. And CMC decreases as hydration ability of hydrophilic groups which decreases relatively. For the nonionic surfactant, partial charge and electronegativity in hydrophobic group increases with the increment of carbon number in hydrophobic group. And CMC decreases because electronegativity of hydrophilic group is decreased with the increment of electronegativity of hydrophilic group. However, with the increase of repeating units in hydrophilic group, the negative partial charge of hydrophilic group increases. So CMC increases because surfactants hydrate rather than form micelles in aqueous solution by the increase of hydration ability.

• Korean Journal of Environmental Agriculture
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• v.27 no.2
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• pp.139-144
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• 2008

A field experiment was conducted to investigate the influence of cultivars and compost on soil microbial activities and diversities in a red pepper-grown field. Compost was applied with 0, 30, and 60M/T $ha^{-1}$ in April and then red pepper seedlings of "Yong-go 4" and "Koeun" were transplanted in May 2007. Soil samples were collected in early August 2007. Measurement of microbial activities was based on a dehydrogenase assay and a fluorescein diacetate hydrolysis. Soil microbial community was characterized with Biolog $EcoPlate^{TM}$ and phospholipid fatty acid(PLFA). Red pepper cultivars did not differentiate the selected soil chemical and microbial properties. Soil pH and soil microbial community changed by amending the soil with 30 and 60 M/T $ha^{-1}$ of compost, and the soil organic matter and potassium content, and soil microbial activities increased in soils amended with 60 M/T $ha^{-1}$ of compost. Red pepper cultivar induced a little different soil chemical properties and microbial activity in soils amended with 60 M/T $ha^{-1}$ of compost even though significant differences were not found in those properties. In conclusion the effects of compost on soil chemical and microbial properties were much higher than red pepper cultivars in short-term period but the effects of red pepper cultivars should be investigated in long-term field test.

• Journal of the Korean GEO-environmental Society
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• v.11 no.1
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• pp.53-59
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• 2010

In seawater deposition condition, the corrosion and chemical attack of grouts are similar to those of concrete structure. Used in domestic MSG (Micro Silica Grouting) mixtured large amounts of silicate materials containing as cement powder is $8,000cm^2/g$ of the specific surface area or more due to the high hydration activity and high-strength, high durability, and features, $C_3A$ content of less than 5% to meet the standards chemical attack of seawater was evaluated as a cement material. Therefore, in this paper, with excellent seawater attack resistant MSG in combination with rapid hardening mineral was used, those of seawater characteristics were evaluated experimentally. Typically, sodium-silicate minerals or rapid hardening cements are used in domestic. About the homogel specimens with combination of MSG and rapid hardening agents for compressive strength, weight and length change characteristics were evaluated experimentally, and so we could present the excellent seawater resistant grouts combination.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.445-449
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• 2012

The activation process of the membrane-electrode assembly (MEA) is important for the mass production of the polymer electrolyte membrane fuel cell. The conventional activation process for the MEA requires excessive time and hydrogen gas and it might become the barrier for the commercialization of the fuel cell. The conventional activation process is based on hydrolysis of ion conducting membrane. In the study, we suggest the cyclic voltammetry (CV) technique as an on-line activation process and the CV activation process consists of two steps : 1) the humidification of the polymer electrolyte membrane and the electrode with 100% RH humidified nitrogen ($N_{2}$) gas, and 2) the removal step of the oxide layer on the surface of the Pt catalyst with CV cycling. The cycling reduces the activation time of the MEA by 2.5 h and use of hydrogen gas by 1/4.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.49-53
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• 2019

Hydrous $MnO_2$ nanowires were easily synthesized by an one-pot synthesis with a simple hydrothermal method. As prepared hydrous $MnO_2$ nanowires were characterized with scanning emission microscopy (SEM), transmit emission microscopy (TEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET). They showed a good catalytic activity with the suitable nano-size of 4-5 nm and morphology. The furfuryl alcohol was selected as a substrate and the reaction was carried out in a toluene solvent at $100^{\circ}C$ under the atmospheric pressure of oxygen. The hydrous $MnO_2$ nanowire catalyst exhibited an excellent yield of furfural with the first-rate selectivity and conversion. The catalytic performance during recycle tests was also carried out and the catalyst showed a good mechanical strength with a negligible loss in the activity over five reaction cycles.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.1
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• pp.92-99
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• 2021

CaO-based by-products composed of CaO, SO3, Al2O3, etc. are generally used as raw materials for CaO compounds. When applied to the recovered water of ready-mixed concrete, the hydration reaction of the powder material is accelerated and concrete performance can be improved. In this study, activated sludge was prepared to apply to the recovered water of ready-mixed concrete by mixing CaO-based hot-rolled slag(C12A7) in the recycling water of ready-m ixed concrete. Cem ent paste setting time and mortar compressive strength performance tests confirmed the effect on the hydration reaction. Therefore, the possibility of concrete application using activated sludge was confirmed.

• Journal of the Korean Ceramic Society
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• v.35 no.5
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• pp.479-485
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• 1998

Raw mateials such as limestone quartzite bauxite and anhydrite were used in the production of mod-ified beloite cement. Two kinds of clinker were synthesized with relatively higher content of $C_2S$ than that of $C_4A_3{\={S}}$ Concerning $C_2S$ the main mineral component borax ($Na_2O\;2B_2O_3\;10H_2O$) was added to stimu-late hydraulic reactivity and this would be possible by stabilizing ${\alpha}'-C_2S$ at room temperature. We had in-tended to compare burning and hydraulic characteristics of clinkers with one another by varying the amount of borax addition and to study the appropriate amount of anhydrite addition needed in the strengthening of cement during hydration. It was concluded that the effective amount of borax addition ne-eded for stabilization of ${\alpha}'-C_2S$ was 5 wt% in 60wt% $C_2S$ inclusive clinker and adding anhydrite in the ra-tio of 1.3 of $SO_3/Al_3O_3$ was appropriate in the production of cement by this clinker. Only ettringite was seen to contribute to the strength without additives but C-S-H was found to form along with ettringite with the addition of borax in the initial stage of hydration.

• Polymer(Korea)
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• v.33 no.2
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• pp.111-117
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• 2009

This study aims to verify for humans the suitability of the enzyme-fixed hydrogel used for the patch sensor of the blood sugar testing system without blood sampling, which utilizes reverse iontophoresis. Using acrylate monomers, hydrogel was synthesized to which a certain unit of enzyme is fixed. In order to analyze the material property of the synthesized hydrogel, a structural analysis was performed using FT-IR spectroscopy, while the DSC was used to verify the thermal stability. In addition, with the UV-Vis spectrophotometer, it was verified that the degree of active enzyme is at least 50% greater than the standard product. The SEM was used to verify secure fixation of the enzyme onto the surface. As a result, it was observed that the enzyme is successfully fixed to the surface. Since the hydrogel makes direct contact with a patient's skin, it is essential to evaluate the toxicity when making direct contact with the skin. For that purpose, various sets of tests were undertaken according to the ISO 10993-cytotoxicity, intracutaneous reactivity, skin irritation test and maximization sensitization. Consequently, it was successfully verified that the enzyme-fixed hydrogel have bioavailability.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.142-150
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• 2023

As global warming continues, the time of invasion of Spodoptera frugiperda has been advanced and the inflow rate has been increasing, leading to great increases in damage to crops. In this study, in order to minimize crop damage caused by S. frugiperda, the control period was set for corn fields through control thresholds, and the control effects according to the chemical spraying methods were investigated in forage corn filed. Even under the condition of 4% injury level during the corn silking stage, the damage rate of ear was 70%, showing an aspect of extensive damage. The economic injury level of S. frugiperda second instar larvae was shown to be 0.7 larvae per stalk, and the control threshold level was shown to be 0.6 larvae. The income was calculated by applying the corn wholesale unit price, and according to the result, even under the condition of injury level of 4%, there was a loss of KRW 895,221/10a, and the higher the injury level, the greater the decrease in income. To control S. frugiperda, the insecticidal effects of 10 single formulations registered for S. frugiperda were tested, and according to the results, four types(emamectin benzoate, chlorantraniliprole, indoxacarb, and spinetoram) showed high insecticidal activity not lower than 93.3%, and three types (chloran- traniliprole, spinetoram, and indoxacarb) were considered to be effective in controlling S. frugiperda as they showed high residual effects through insecticidal effect persistence tests. Therefore, conventional control and aerial control were conducted twice at 7-day intervals with indoxacarb SC and chlorantraniliprol WP, which show high activity against S. frugiperda, respectively, prior to the silking of forage corn. As a result, conventional control showed higher control values, 46.3%p in the case of indoxacarb SC and 21.7%p in the case of chlorantraniliprol WP, than aerial control through the primary control. In the secondary control too, higher control values of 26.7%p in the case of indoxacarb SC and 40.4%p in the case of chlorantraniliprol WP were found in conventional control than in aerial control. Therefore, it is considered necessary to prepare measures to improve the control effects in the recent situation where alternative methods for manpower control are widely used.