• Journal of Environmental Science International
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• v.15 no.3
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• pp.203-209
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• 2006

In predicting oxidants concentration, the most important fact is to select a suitable photochemical reaction mechanism. Sensitivity analysis of $O_3$ and other important photochemical oxidants concentrations was conducted by using CBM-IV model. The predicted oxidants concentration was considerably related with the initial concentration of formaldehyde, $[NO_2]/[NO],\;NO_x$, RH and RCHO. As the initial concentration of formaldehyde increased, concentration of $NO_2$ increased. $O_3$ concentration was proportional to the $[NO_2]/[NO]$ ratio. When the initial concentrations of RH and RCHO were high, photochemical reaction was more reactive, including more rapid conversion of NO to $NO_2$ and increased oxidants. Also, the sensitivities of ozone formation to rate constants, $K_l,\;K_2\;and\;K_3$ in the $NO_2$ photolysis were studied.

• Journal of Environmental Science International
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• v.25 no.12
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• pp.1717-1726
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• 2016

In this study, the reductive decolorization of three acid and basic dyes using modified zero-valent iron (i.e., acid-washed iron (Aw/Fe) and palladium coated iron (Pd/Fe)) at various pH conditions (pH 3~5) was experimentally investigated and the decolorization characteristics were evaluated by analyzing the absorbance spectra and reaction kinetics. In the case of acid dyes such as methyl orange and eriochrome black T, color removal efficiencies increased as initial pH of the dye solution decreased. However, the color removal of methylene blue, a basic dye, was not affected much by the initial pH and more than 70% of color was removed within 10 min. During the decolorization reaction, the absorbance of methyl orange (${\lambda}_{max}=464nm$) and eriochrome black T (${\lambda}_{max}=528nm$) decreased in the visible range but increased in the UV range. The absorbance of methylene blue (${\lambda}_{max}=664nm$) also decreased gradually in the visible range. Pseudo-zero order, pseudo-first order, and pseudo-second order kinetic models were used to analyze the reaction kinetics. The pseudo-second order kinetic model was found to be the best with good correlation. The decolorization reaction rate constants ($k_2$) of methylene blue were relatively higher than those of methyl orange and eriochrome black T. The reaction rate constants of methyl orange and eriochrome black T increased with a decrease in the initial pH.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.141-146
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• 2011

Loess, a natural clay, was evaluated as an adsorbent for the decolorization of Acid Orange II, an azo and reactive dye, from aqueous solution. Adsorption studies were performed at $30^{\circ}C$ and the effect of reaction time, loess dosage, initial concentration, loess particle size, pH, agitation rate were investigated to determine the optimum operation conditions. The removal efficiencies of color were measured to evaluate the effectiveness of loess. From this study, it was found that optimal reaction time was 10 min. Color removal efficiencies of Acid Orange II were increased as higher loess dosage, initial concentration and agitation rate. However, color removal efficiencies decreased when pH is high and loess particle becomes large. Adsorption of Acid Orange II fitted to the pseudo-second-order rate kinetics more than first-order rate kinetics. Langmuir and Freundlich adsorption isotherm constants and correlation coefficients were calculated and compared. It was concluded that the adsorption data of Acid Orange II onto loess fitted to the Freundlich model more than Langmuir model.

• Analytical Science and Technology
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• v.30 no.3
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• pp.138-145
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• 2017

Microwave-assisted organic synthesis has gained a remarkable interest over the past years because of its advantages - (i) rapid energy transfer and superheating, (ii) higher yield and rapid reaction, (iii) cleaner reactions. Ionic liquids are well known for their unique properties such as negligible vapor pressure and high thermal stability. With these properties, ionic liquids have gained increasing attention as green, multi-use reaction media. Recently, ionic liquids have been applied as reaction media for biocatalysis. Lipase-catalyzed reactions in ionic liquids provide high activity and yield compared to conventional organic solvents or solvent free system. Since polar molecules are generally good absorbent to microwave radiation, ionic liquids were investigated as reaction media to improve activity and productivity. In this study, therefore, the effect of microwave irradiation in ionic liquids was investigated on lipase catalyzed reactions such as benzyl acetate synthesis and caffeic acid phenethyl ester synthesis. Comparing to conventional heating, microwave heating showed almost the same final conversion but increased initial reaction rate (3.03 mM/min) compared to 2.11 mM/min in conventional heating at $50^{\circ}C$.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.6
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• pp.841-849
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• 2012

The effluent quality of phosphorus is strengthened by the national standard to conserve water resources to lessen the eutrophication threat. The soluble phosphate in the wastewater effluent can be removed using the converter slag as solid waste produced through the steel making process. The experiments for removal efficiencies and removal constants were performed for this research with the artificial wastewater following several different conditions, particle size, phosphate concentration and initial pH. The correlation coefficients of Freundlich adsorption isothem were 0.9505 for $PS_A$, 0.9183 for $PS_B$, respectively. The removal efficiency was 87-94 % for $PS_A$ and 90-96 % for $PS_B$ respectively. The pH of the wastewater was elevated to pH 11.8 for the initial pH 8.5, phosphate removal efficiency was the highest as 84 % ~ 98 %. In case of 10 mg/L of the intial phosphate, the removal efficiency was 96 ~ 98 %. The more initial pH increases, the higher the reaction rate constant is.

• Journal of Mechanical Science and Technology
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• v.15 no.4
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• pp.473-481
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• 2001

By depicting the transfer of heat and combustion reaction to take place within thin gas layers close to the propellant surface burning in a steady-state fashion, a mathematical equation has been deduced to describe the burning rate of solid propellant as a function of initial grain temperature and chamber pressure. It has been also assumed that chemical reaction could take place in premixing-diffusing zone but were carried out mainly in the reaction-flame zone. All these phenomena taken place in each zone of combustion have been assumed to be steady-state. In the present investigation, the equation, γ=$\kappa$$.$(1/R(T(sub)i+C))(sup)n$.$exp(-E(sub)a/R(T(sub)i+C))(P/z) is being presented and it is compared with experimental data. The proposed model has been tested and evaluated vis-a-vis strand burner data for three different propellants based on CTPB, and it has been found that the deviation of the computed burning rates from the measured rates ranged up to 2%.

• Journal of the Korean Applied Science and Technology
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• v.25 no.4
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• pp.418-428
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• 2008

Transesterification of fat of Tra catfish with methanol in the presence of the KOH catalyst yields fatty acid methyl esters (FAME) and glycerol (GL). The effects of the reaction temperature and reaction time on rate constants and kinetic order were investigated. Three regions were observed. In the initial stage, the immiscibility of the Tra fat and methanol limited the reaction rate, hence this region was controlled by the mass transfer. Subsequent to this region, produced FAME like a co-solvent made the reaction mixture homogeneous, therefore the conversion rate increased rapidly so it was controlled by the kinetic parameters of the reaction until the equilibrium was approached in the final slow region. A second-order kinetic mechanism was proposed involving second regions for the forward reaction. The rate determining step for the overall KOH catalyzed-methanolysis of Tra fat was the conversion of triglycerides (TG) to diglycerides (DG). This rate constant was increased from 0.003 to $0.019min^{-1}$ when the reaction temperature was increased from 35 to $60^{\circ}C$. Its calculated activation energy was 14.379 ($kcal.mol^{-1}$).

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.659-664
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• 2007

The objective of this study is to evaluate the detoxification method for the endocrine disrupting chemicals by manganese oxide. Manganese coated sand and bisphenol-A (BPA) was used as the reactive medium and the contaminant. Results showed that manganese oxide effectively degrades BPA by oxidative coupling reaction. The nonlinear oxidative coupling reaction orders were obtained for BPA and oxide, respectively. The reaction rate of BPA decreased as initial BPA concentration increased, as oxide loading decreased and as pH increased. The higher ionic strength, the higher reaction rate was observed. Divalent cations were adsorbed on the oxide surfaces, resulting in the decreased degradation rate of BPA.

• Journal of Environmental Health Sciences
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• v.30 no.5 s.81
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• pp.358-365
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• 2004

The photocatalytic oxidation of Rhodamine B(RhB) was studied using photocatalytic reactor filled with module of quartz tube. Module of quartz tube consisted of small quartz tube (inner diameter, 1.5 mm; outer diameter, 3 mm) bundle coated with powder $TiO_2$ and uncoated large quartz tube (inner diameter, 20 mm; outer diameter, 22 mm). Two 30 W germicidal lamp was used as the light source and the reactor volume was 0.5 l. The effects of parameters such as the coating materials and numbers, initial concentration, $H_{2}O_2$ dose and metal deposition (Ag, Pt and Fe) and simultaneous application of $H_{2}O_2$ and metal deposition. The results showed that the initial reaction constant of quartz module coated with powder $TiO_2$ was higher 1.4 time than that of the $TiO_2$ sol and optimum coating number is twice. In order to increase reaction rate, simultaneous application of photocatalytic and photo-fenton reaction using Fe coating and dose $H_{2}O_2$ dose increased reaction rate largely.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.51-59
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• 2007

These studies show that I applied to functional insole (a specific A company) for minimizing shocks and sprain people's ankle arising from running. How to an effect on human body which studied a kinematics and kinetics from 10 college students during experiments. This study imposes several conditions by barefoot, normal running shoes and put functional insole shoes ran under average $2.0{\pm}0.24\;m$/sec by motion analysis and ground reaction force that used to specific A company. First of all, motion analysis was caused by achilles tendon angle, angle of the lower leg, angle of the knee, initial sole angle and barefoot angle. The result of comparative analysis can be summarized as below. Motion analysis showed that statically approximates other results from achilles tendon angle (p<.01), initial ankle angle(p<.05), initial sole angle(p<.001) and barefoot angle(p<.001). Ground reaction force also showed that statically approximates other results from impact peak timing (p<.001), Maximum loading rate(p<.001), Maximum loading rate timing (p<.001) and impulse of first 20 percent (p<.001). Above experiment values known that there was statically difference between Motion analysis and Ground reaction force under absorbing of the functional insole shoes which was not have an effect on our body for kinetics and kinematics.