• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.1
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• pp.26-32
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• 1979

Dry oxidation and wet oxidation processes of silicon have been examined experimentally. The oxidation temperatures were 1.10$0^{\circ}C$, 1.15$0^{\circ}C$, and 1.200 $^{\circ}C$, and oxygen flow rate was changed from 0.2 liter/min to 2.8 liter/min. From the experimental measurements, oxidation temperaturel time and oxygen flow rate have been tabutated for oxide layers 0.1$\mu$ - 1.0$\mu$ in thickness. The quality of the grown oxide layer has been investigated In terms of the dielectric constant, breakdown voltage, fixed surface charge densify (Qss/q) and mobile charge density (Q /q). From these measurements, it is concluded that the quality of the oxide layer is sufficient to expect the normal operation of MOS transistors.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3539-3543
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• 2012

Butacaine sulfate is an ester of p-aminobenzoic acid which has been widely used as a local anaesthetic and it is a long standing agent particularly for spinal anaesthesia. For this reason, a kinetic study of oxidation of butacaine sulfate by sodium N-chlorobenzenesulfonamide (chloramine-B or CAB) has been carried out in $HClO_4$ medium at 303 K in order to explore this redox system mechanistic chemistry. The rate shows a first-order dependence on both $[CAB]_o$, and $[substrate]_o$, and a fractional-order dependence on acid concentration. Decrease of dielectric constant of the medium, by adding methanol, increases the rate of the reaction. Variation of ionic strength and addition of benzenesulfonamide or NaCl have no significant effect on the rate. The reaction was studied at different temperatures and the activation parameters have been evaluated. The stoichiometry of the reaction has been found to be 1:2 and the oxidation products have been identified by spectral analysis. The observed results have been explained by plausible mechanism and the related rate law has been deduced.

• Korean Journal of Materials Research
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• v.12 no.1
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• pp.68-74
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• 2002

The lead has to be removed for the recycling of copper alloy. The lead cannot be removed from the copper alloy by oxidation. It can be removed by the evaporation because of its high vapor pressure. However, rare information is found on removal of lead from copper alloy. The purpose of present work is to provide a fundamental knowledges on the removal of lead from the copper alloy by evaporation. Gas injection was made in molten copper alloy, and the evaporation rate of lead was measured. The influence of Ar gas flow rata(2~4 L/min), initial contents of lead(2~4wt%Pb), temperature(1200~140$0^{\circ}C$) was investigated based on the thermodynamic and the kinetics. The rate constant is increased with increasing flow rate of Ar and temperature. Though amount of lead removed is increased with higher initial lead concentration, the rate constant is not changed significantly. The activation energy is estimated from the temperature dependence of the rate constant. Also removal of lead from the copper by adding chloride was made for the comparison.

• Korean Journal of Community Nutrition
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• v.20 no.6
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• pp.468-478
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• 2015

Objectives: The objective of this study was to evaluate the thermic effects, the macronutrient oxidation rates and the satiety of medium-chain triglycerides (MCT). Methods: The thermic effects of two meals containing MCT or long-chain triglycerides (LCT) were compared in ten healthy men (mean age $24.4{\pm}2.9years$). Energy content of the meal was 30% of resting metabolic rate of each subject. Metabolic rate and macronutrient oxidation rate were measured before the meals and for 6 hours after the meals by indirect calorimetry. Satiety was estimated by using visual analogue scales (VAS) at 8 times (before the meal and for 6 hours after meal). Results: Total thermic effect of MCT meal (42.8 kcal, 8.0% of energy intake) was significantly higher than that (26.8 kcal, 5.1% of energy intake) of the LCT meal. Mean postprandial oxygen consumption was also significantly different between the two types of meals (MCT meal: $0.29{\pm}0.35L/min$, LCT meal: $0.28{\pm}0.27L/min$). There were no significant differences in total postprandial carbohydrate and fat oxidation rates between the two meals. However, from 30 to 120 minutes after consumption of meals, the fat oxidation rate of MCT meal was significantly higher than that of the LCT meal. Comparison of satiety values (hunger, fullness and appetite) between the two meals showed that MCT meal maintained satiety for a longer time than the LCT meal. Conclusions: This study showed the possibility that long-term substitution of MCT for LCT would produce weight loss if energy intake remained constant.

• Tribology and Lubricants
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• v.18 no.6
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• pp.396-401
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• 2002

ln this paper, the fuction of molybdenum dialkyl dithiophosphate (MoDTP) as an oxidation inhibitor of mineral oils was investigated and compared with 2,6-Di-tert-Butyl-4-Methylphenol (DBMP). Oxidation tests were conducted using an oxygen absorption apparatus. MoDTP showed anti-oxidation property, and length of induction time prolonged by increasing MoDTP concentration. However the induction time of DBMP was longer than those of MoDTP. The anti-oxidation property of MoDTP was found to be inferior to that of DBMP The capability of hydroperoxide decomposition ability with MoDTP was much greater than that with DBMP. However the rate constant of radical scavenging with MoDTP was much better than that with DBMP. It was found that the performance of MoDTP is exellent with respect to hydroperoxide decomposition but it is susceptible to chemical decomposition. From the fact that formation of phenol was observed when MoDTP was added to hexane solution of cumene hydroperoxide (CHPO), it is indicated that the decomposition of hydroperoxide with MoDTP occurs by means of ionic mechanism.

• Korean Journal of Environmental Agriculture
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• v.14 no.1
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• pp.7-14
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• 1995

This research was conducted to apply the QUAL2E model to be adopted to the Nam river under current water quality conditions. The survey area of total 60 Km was divided into five reaches. Each reach was then subdivided into the uniform computational elements of 1.5 Km. Based on the stream characteristics, nine sampling stations consisting of six at main streams and three at tributaries were selected. The field data were obtained from the selected stations twice during October of 1991 and May of 1992, which represented the cold weather and low flow, also the warm weather and low flow conditions, respectively. As the results of sensitivity analysis of the model, the important parameters were the rates of BOD decay, Org-N oxidation, $NH_3-N$ oxidation, Org-P decay. The calibrated and verified results by QUAL2E model were correlation coefficient of $0.45{\sim}0.94$. The results displayed a good agreement between the variables of the field measurements and the model simulations, indicating a potential use of the QUAL2E model for the water quality assessment in the Nam River.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1385-1390
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• 2014

Hydrofluoroethers (HFEs) are developed as a suitable for the replacement of environmentally hazardous CFCs and are termed as third generation refrigerants. One of the major products of decomposition of HFEs in the atmosphere is a fluoroester. The present study relates to the OH and Cl initiated oxidation of $CF_3C(O)OCH_2CF_3$ formed from the oxidation of HFE-356mff. The latter is used as a solvent in the industry and reaches the atmosphere without any degradation. Kinetics of the titled molecule has been studied at MPWB1K/6-31+G(d,p) level of theory. Single point energy calculations have been made at G2(MP2) level of theory and barrier heights are determined. The rate constants are calculated using canonical transition state theory. Tunnelling correction are made using one-dimensional Eckart potential barrier. The rate constant calculated during the present study are compared with the experimental values determined using relative rate method and FTIR detection technique.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.1
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• pp.91-99
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• 2008

A multilayer tower-type photoreactor, in which $TiO_2$-coated glass-tubes were installed, was used to measure the vapor-phase BTEX removal efficiencies by ozone oxidation ($O_3$/UV), photocatalytic oxidation ($TiO_2$/UV) and the combination of ozone and photocatalytic oxidation ($O_3/TiO_2$/UV) process, respectively. The experiments were conducted under various relative humidities, temperatures, ozone concentrations, gas flow rates and BTEX concentrations. As a result, the BTEX removal efficiency and the oxidation rate by $O_3/TiO_2$/UV system were highest, compared to $O_3$/UV and $TiO_2$/UV system. The $O_3/TiO_2$/UV system accelerated the low oxidation rate of low-concentration organic compounds and removed organic compounds to a large extent in a fixed volume of reactor in a short time. Therefore, $O_3/TiO_2$/UV system as a superimposed oxidation technology was developed to efficiently and economically treat refractory VOCs. Also, this study demonstrated feasibility of a technology to scale up a photoreactor from lab-scale to pilot-scale, which uses (i) a separated light-source chamber and a light distribution system, (ii) catalyst fixing to glass-tube media, and (iii) unit connection in series and/or parallel. The experimental results from $O_3/TiO_2$/UV system showed that (i) the highest BTEX removal efficiencies were obtained under relative humidity ranging from 50 to 55% and temperature ranging from 40 to $50^{\circ}C$, and (ii) the removal efficiencies linearly increased with ozone dosage and decreased with gas flow rate. When applying Langmuir-Hinshelwood model to $TiO_2$/UV and $O_3/TiO_2$/UV system, reaction rate constant for $O_3/TiO_2$/UV system was larger than that for $TiO_2$/UV system, however, it was found that adsorption constant for $O_3/TiO_2$/UV system was smaller than that for $TiO_2$/UV system due to competitive adsorption between organics and ozone.

• Journal of the Korean institute of surface engineering
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• v.28 no.6
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• pp.333-342
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• 1995

Stainless steels are widely selected as commercial engineering materials mainly because of their excellent corrosion resistance, oxidation resistance and strength. Because the manufacturing temperature of stainless steels is relatively high, the chemical and physical properties of the oxide film which was formed on the stainless steels are of importance in determining the rate of oxidation and the life of equipment exposed to high temperature oxidizing environments. In this study, the oxidation behavior of S. S. 304 and S. S. 430 added by a small amount of oxygen active elements(each +0.5wt% Hf and Y) was studied to improve oxidation resistance. The results of cyclic and isothermal oxidation on S. S. 304 added by OAE showed relatively poor oxidation resistance due to spallations and cracks of $Cr_2O_3$ layer. But all S. S. 430+0.5wt% OAE maintained constant oxidation rates and stable oxide layers at high temperature environment. Especially S. S. 430+0.5wt% Y formed a $Cr_2O_3$ oxide layer and improved cyclic oxidation resistance preventing loss of protective layers about 1000 hours at $1000^{\circ}C$

• Journal of Environmental Science International
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• v.13 no.1
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• pp.37-40
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• 2004

In this study, the decomposition of gas-phase TCE, Benzene and Toluene, in air streams by direct UV Photolysis and UV/TiO$_2$ process was studied. For direct UV Photolysis, by regressing with computer calculation to the experimental results the value of reaction rate constant k of TCE, Toluene and Benzene in this work were determined to be 0.00392s$\^$-l/, 0.00230s$\^$-1/ and 0.00126s$\^$-1/, respectively. And the adsorption constant K of TCE, Toluene and Benzene in this work were determined to be 0.0519 mol$\^$-l/ ,0.0313mo1$\^$-1/ and 0.0084mo1$\^$-1/, respectively. For UV/TiO$_2$ system by regressing with computer calculation to the experimental results the value of reaction rate constant k of TCE, Toluene, and Benzene in this work were determined to be 5.74g/$\ell$$.$min, 3.85g/$\ell$$.$min, and 1.18g/$\ell$$.$min, respectively. And the catalyst adsorption constant K of TCE, Toluene, and Benzene in this work were determined to be 0.0005㎥/mg, 0.0043㎥/mg and 0.0048㎥/mg, respectively.