• Polymer(Korea)
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• v.30 no.6
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• pp.505-511
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• 2006

We tried to prepare polystyrene composite particles containing carbon black by suspension polymerization with water as a reaction medium. Hydrophobic silica was selected as a stabilizer and oil-soluble azobisisobutyronitrile (AIBN), as an initiator. All polymerization reactions were carried out at a fixed temperature of $75^{\circ}C$. Stabilizer concentration was varied from $0.17{\sim}3.33wt%$ compared to water, where particles with $7.96{\mu}m$ in average diameter were obtained at 1.57 wt% of stabilizer. Increase in divinylbenzene concentration, as a crosslinking agent, from $0.1{\sim}1.0 wt%$ compared to monomer exhibited a large increase in average particle diameter Incorporation of 1wt% of carbon black compared to monomer produced an increase in average diameter It is speculated that viscosity lower than that necessary to induce even dispersion of carbon black particles led to poor dispersion, and as a result, large particles. For a styrene mixture containing 3 wt% carton black compared to monomer, enhanced dispersion due to an increase in carbon black concentration reduced average particle diameters. For styrene mixtures containing 1 and 3 wt% carbon black compared to monomer, preparticles before polymerization and polymer composite particles after polymerization showed a similar tendency towards particle formation. When carbon black concentration compared to monomer was increased to 5 and 7 wt%, styrene mixtures exhibited a large increase in viscosity and thus better dispersion of carbon black particles, which led to a decrease in preparticle diameters. However, these particles experienced agglomeration in the polymerization process, and polystyrene composite particles increased in average diameter.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.452-455
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• 2000

There are increasingly important financial incentives and environmental consideration to improve the effluent quality of wastewater from domestic and industrial users. The activated sludge process is a widely used biological wastewater treatment process. The activated sludge process is complicated due to the many factors such as the variation of influent flowrate and concentration, the complexity of biological reactions and the various operation conditions. Nowadays, not only suspended solids and residual carbon, but also nitrogen and phosphorous concentration of the effluent water must be taken into account for the design and operation of wastewater treatment plants. Also, the effluent quality to be met are more stringent. Therefore, an intelligent control approach is required in order to successful biological nitrogen removal. In this paper, the strategies for dosage of extra carbon in the anoxic zone and DO concentration in the aerobic zone are presented and evaluated through the simulation using the denitrification layout of the IWA simulation benchmark implemented by Matlab$\^$/5.3/Simulink$\^$/3.0. The control strategy to achieve sufficient denitrification rates in an anoxic zone. Methanol is used as an external extra carbon source. The external extra carbon source is required for the nitrogen removal process because nitrogen and organic concentration are fluctuated in the influent flowrate. The dissolved oxygen is calculated by So concentration in the activated sludge model NO.1. The air flowrate of each aerobic reactor is intelligently controlled to achieve the predefined setpoints. Air flowrate is adjusted by the fuzzy logic controller that includes two inputs and one output. The objective function for the optimization procedure is designed to improve effluent quality and reduce the operating cost.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.9
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• pp.707-711
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• 2013

Carbon nanotubes(CNT) has strength and chemical stability, greatly conductivity characteristics. In particular, MWCNT (multi-walled carbon nanotubes) show rapidly resistance sensitive for changes in the ambient gas, and therefore they are ideal materials to gas sensor. So, we fabricated NOx gas sensors structured MOS-FET using MWCNT (multi-walled carbon nanotubes) material. We investigate the change resistance of NOx gas sensors based on MOS-FET with ultra lean NOx gas concentrations absorption. And NOx gas sensors show sensitivity on the change of gate-source voltage ($V_{gs}=0[V]$ or $V_{gs}=3.5[V]$). The gas sensors show the increase of sensitivity with increasing the temperature (largest value at $40^{\circ}C$). On the other hand, the sensitivity of sensors decreased with increasing of NOx gas concentration. In addition, We obtained the adsorption energy($U_a$), $U_a$ = 0.06714[eV] at the NOx gas concentration of 8[ppm], $U_a$ = 0.06769[eV] at 16[ppm], $U_a$ = 0.06847[eV] at 24[ppm] and $U_a$ = 0.06842[eV] at 32[ppm], of NOx gas molecules concentration on the MWCNT gas sensors surface with using the Arrhenius plots. As a result, the saturation phenomena is occurred by NOx gas injection of concentration for 32[ppm].

• Journal of Environmental Science International
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• v.18 no.12
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• pp.1411-1416
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• 2009

Several adsorbents were tried to remove the selenium ions from industrial wastewater and the following ascending order of the adsorption performance for the selenium at pH 9 was observed: cation exchange resin < chelate resin < zeolite < brown marine algae < granular activated carbon < anion exchange resin. Initial concentration of selenium(146 mg/L) in industrial wastewater was reduced to 63 mg/L of selenium at pH 9 by neutralization process. The maximum uptake of Se calculated from the Langmuir isotherm with anion exchange resin was 0.091 mmol/g at pH 10 and that with granular activated carbon was 0.083 mmol/g at pH 6. The affinity coefficients of Se ion towards anion exchange resin and granular activated carbon were 3.263 L/mmol at pH 10 and 0.873 L/mmol at pH 6, respectively. The sorption performance of anion exchange resin at the low concentration of Se, namely, was much better than that of granular activated carbon. The Se ions from industrial wastewater throughout neutralization process and two steps of adsorption using anion exchange resin was removed to 97.7%.

• Carbon letters
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• v.9 no.3
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• pp.181-187
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• 2008

Batch sorption experiments were carried out for the removal of metylene blue from its aqueous solution using $H_3PO_4$ activated Acacia arabica carbon (AAC). The prepared activated carbon was characterized and was found as an effective adsorbent material. The operating variables studied were initial metylene blue concentration, AAC concentration and solution pH. AAC activated carbon posses a maximum sorption capacity for the range of initial dye concentrations studied (60~100 mg $L^{-1}$). The sorption kinetics were analyzed using reversible first order kinetics, second order, reversible first order, pseudo-first order, and pseudo-second order model. The sorption data tend to fit very well in pseudo-second order model for the entire sorption time. The average pseudo-second order rate constant, $K_{II}$ and regression coefficient value were determined to be 0.0174 mg $g^{-1}$ $min^{-1}$ and 0.9977. The biosorption process also fit well to reversible I order kinetics with a regression coefficient of 0.9878.

• Archives of Pharmacal Research
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• v.25 no.4
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• pp.541-545
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• 2002

Pharmacokinetic characteristics of Acebutolol and its main metabolite, diacetolol, following a single 10 mg/kg oral dose, were investigated in rabbits with carbon tetrachloride-induced hepatic failure. Plasma concentrations of acebutolol and diacetolol were determined by a high performance liquid chromatography assay. The area under the plasma concentration-time curves (AUC) and maximum plasma concentration ($C_{max}$) of acebutolol were significantly increased in moderate and severe carbon tetrachloride-induced hepatic failure rabbits. The ratio of the diacetolol to total acebutolol in plasma (i.e., metabolite percentage rate) was significantly decreased in moderate and severe carbon tetrachloride-induced hepatic failure rabbits. Volume of distribution ($V_{d}$) and total body clearance ($CL_{t}$) of acebutolol were significantly decreased in moderate and severe carbon tetrachloride-induced hepatic failure rabbits. Slope of terminal phase ($\beta$) of acebutolol was significantly decreased in hepatic failure rabbits. These findings suggest that the $V_{d},{\;}CL_{t}$ and $\beta$ of acebutolol were significantly decreased as a result of inhibition of the hepatic metabolism in moderate to severe hepatic failure rabbits. Therefore, dose adjustment may be necessary for acebutolol in hypertensive patients with hepatic damage.

• Journal of Environmental Science International
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• v.31 no.11
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• pp.951-958
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• 2022

The aim of this study was to determine the optimum level of carbon dioxide to maximize the quality and yields of strawberries cultivated in a greenhouse. Specifically, two strawberry cultivars, namely, 'Seolhyang' and 'Maehyang', were subjected to varying concentrations of carbon dioxide and patterns linked to their productivity were noted. Both cultivars showed improvements across various physical variables (i.e., leaf area, crown diameter, plant height, fresh weight, and dry weight) when carbon dioxide concentrations were at 1,500 ppm. The optimum carbon dioxide concentration for increased fruit yields and quality was 1,000 ppm. When carbon dioxide was at 1,000 ppm the yields of 'Seolhyang' and 'Maehyang' increased by 1.99 and 1.78 times, respectively, compared to control plants. The influence of carbon dioxide on fruit color was negligible. However, the carbon dioxide increased the sugar content and sugar-acid ratio of the experimental fruits compared to control plants. Specifically, the sugar-acid ratio, which is directly related to taste, was at its highest when the concentration of carbon dioxide was at 1,000 ppm (i.e., for both 'Seolhyang' and 'Maehyang'). Overall, the application of carbon dioxide culminated in improved yields and fruit quality for both cultivars of interest.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.4
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• pp.466-477
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• 2007

To understand particle pollution phenomena caused by vehicles, black carbon (BC) concentrations were continuously monitored using an aethalometer at a roadside in Seoul during the period of May 79 to 25, 2005. The BC concentration was highly fluctuated for a short duration, responding to the traffic situation on the road. The lowest BC concentration was observed between 2 and 5 a.m. The local highest BC concentrations were observed during the periods of both morning and evening rush hours. Change in traffic volume accounts for the trend of hourly averaged BC concentrations from the late evening to the morning. Particularly, the slower increase of BC concentration on Sunday seems to respond directly the lower traffic volume in the morning rush hours. From the comparison with a previous work, it is concluded that the BC concentration around midday hours might be dependent on the distance from a road.

• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.241-246
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• 1989

Continuous on-line monitoring of cell concentration and growth rate in aerobic batch fermentation process was carried out by analyzing the exhaust gas composition of tormentor with a quadrupole mass spectrometer. From the mass spectrometric analyses of major gaseous components, i.e. $N_2$, $O_2$, $CO_2$ and $H_2O$, and the material balance equations for oxygen and carbon dioxide, oxygen uptake rate (OUR) rind carbon dioxide evolution rate (CER) were instantaneously calculated using a computer (16-bit IBM PC-AT) interfaced to a quadrupole mass spectrometer. The calculated OUR and CER data were used for the estimation of cell concentration and growth rate of Candida utilis during batch culture. It was found that the cell concentration could be satisfactorily estimated from the data of OUR arid CER during the culture and this method could be successfully und for the continuous monitoring of cell growth and growth rate.

• Corrosion Science and Technology
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• v.19 no.2
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• pp.75-81
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• 2020

To reduce structural weight, light metals, including aluminum and magnesium alloys, have been widely used in various industries such as aircraft, transportation and automobiles. Recently, composite materials such as Carbon Fiber Reinforced Plastics (CFRP) and Graphite Epoxy Composite Material (GECM) have also been applied. However, aluminum and its alloys suffer corrosion from various factors, which include aggressive ions, pH, solution temperature and galvanic contact by potential difference. Moreover, carbon fiber in CFRP and GECM is a very efficient cathode, and very noble in the galvanic series. Galvanic contact between carbon fiber composites and metals in electrolytes such as rain or seawater, is highly undesirable. Notwithstanding the potentially dangerous effects of chloride and temperature, there is little research on galvanic corrosion according to chloride concentration and temperature. This work focused on the effects of chloride concentration and solution temperature on AA7075T6. The increased galvanic corrosion between CRFP and AA7075T6 was evaluated by electrochemical experiments, and these effects were elucidated.