• Food Science of Animal Resources
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• 제43권2호
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• pp.220-231
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• 2023

Although omega-3 fatty acids including docosahexaenoic acid (DHA) contain various health-promoting effects, their poor aqueous solubility and stability make them difficult to be induced in dairy foods. The aims of this research were to manufacture casein derivative-based delivery system using acid-induced gelation method with glucono-σ-lactone and to investigate the effects of production variables, such as pH and charged amount of linoleic acid, on the physicochemical properties of delivery systems and oxidative stability of DHA during storage in model milk. Covalent modification with linoleic acid resulted in the production of casein derivatives with varying degrees of modification. As pH was reduced from 5.0 to 4.8 and the charged amount of linoleic acid was increased from 0% to 30%, an increase in particle size of casein derivative-based delivery systems was observed. The encapsulation efficiency of DHA was increased with decreased pH and increased charged amount of linoleic acid. The use of delivery system for DHA resulted in a decrease in the development of primary and secondary oxidation products. An increase in the degree of modification of casein derivatives with linoleic acid resulted in a decrease in the formation of primary and secondary oxidation products than of free DHA indicating that delivery systems could enhance the oxidative stability of DHA during storage in model milk. In conclusions, casein derivatives can be an effective delivery system for DHA and charged amount of linoleic acid played a key role determining the physicochemical characteristics of delivery system and oxidative stability of DHA.

• Economic and Environmental Geology
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• 제43권2호
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• pp.137-148
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• 2010

The Myoungbong mine located in Boseong-gun, Jellanamdo consists of Au-Ag bearing quartz veins which filled the fissures of Bulguksa granitic rocks of Cretaceous. The tailings obtained from the Myungbong mine were used to investigate the effects of various processes, such as oxidation of primary sulfides and formation(alteration) of secondary and/or tertiary minerals, on arsenic immobilization in tailings. This study was conducted via both mineralogical and chemical methods. Mineralogical methods used included gravity and magnetic separation, ultrasonic cleaning, and instrumental analyses(X-ray diffractometry, energy-dispersive spectroscopy, and electron probe microanalyzer) and aqua regia extraction technique for soils was applied to determine the elemental concentrations in the tailings. Iron (oxy)hydroxides formed as a result of oxidation of tailings were identified as three specific forms. The first form filled in rims and fissures of primary pyrites. The second one precipitated and coated the surfaces of gangue minerals and the final form was altered into yukonites. Initially, large amounts of acid-generating minerals, such as pyrite and arsenopyrite, might make the rapid progress of oxidation reactions, and lots of secondary minerals including iron (oxy)hydroxides and scorodite were formed. The rate of pH decrease in tailings diminished, in addition, as the exposure time of tailings to oxidation environments was prolonged and the acid-generating minerals were depleted. Rather, it is speculated that the pH of tailings increased, as the contribution of pH neutralization reactions by calcite contained in surrounding parental rocks became larger. The stability of secondary minerals, such as scorodite, were deteriorated due to the increase in pH, and finally arsenic might be leached out. Subsequently, calcimn and arsenic ions dissociated from calcites and scorodites were locally concentrated, and yukonite could be grown tertiarily. It is confirmed that this tertiary yukonite which is one of arsenate minerals and contains arsenic in high level plays a crucial role in immobilizing arsenic in tailings. In addition to immobilization of arsenic in yukonites, the results indicate that a huge amount of iron (oxy)hydroxides formed by weathering of pyrite which is one of typical primary minerals in tailings can strongly control arsenic behavior as well. Consequently, this study elucidates that through a sequence of various processes, arsenic which was leached out as a result of weathering of primary minerals, such as arsenopyrite, and/or redissolved from secondary minerals, such as scorodite, might be immobilized by various sorption reactions including adsorption, coprecipiation, and absorption.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제23권3호
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• pp.194-198
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• 2010

Recently as the electronic devices are getting to be more and more smaller, transformers are needed to be micro fabricated using MEMS technology. In this paper transformers have been fabricated and measured by depositing insulation layer to reduce the loss of eddy current and in the middle core a high permeability permalloy was designed based on the turns ratio between primary coil and secondary coil which are 1:1 transformers. (the number of turns of primary coil and secondary coil: 3/3, 5/5, 7/7). The size of the transformers including ground shield are $1mm{\times}1.5mm$, $1mm{\times}1.95mm$, $1mm{\times}2.35mm$ respectively. The line width, pitch and the height of post are 50um. Based on the measured data from the micro fabricated transformers, the 3/3 turns in the primary coil and secondary coil showed the lowest insertion loss with 1.5 dB at 480 MHz and the 7/7 turns in the primary coil and secondary coil showed the highest insertion loss with 2.5 dB at 280 MHz. Also confirmed that the bandwidth goes up as the number of turns goes down. There was some difference between the actual measured data and the HFSS simulation result. It looks as if it is an error of the difference between oxidation of copper or the permeability of SU-8.

• Journal of Korean Society of Water and Wastewater
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• 제18권3호
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• pp.377-384
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• 2004

In the present study, a feasibility of an advanced oxidation process using UV/Hydrogen peroxide($H_2O_2$) system equipped with a medium pressure lamp for secondary effluent reclamation was investigated. Initial concentration of $H_2O_2$ and pH were changed to determine the optimum operation condition for the system. The removal efficiency of color was than 80% with 14.3mg/L of initial $H_2O_2$ and 5 minute of contact time in the UV/$H_2O_2$ system. The color removal was analyzed using first-order reaction equation. The dependence of rate constant (k) on initial $H_2O_2$ represented the rational relationship with maximum value. Residual $H_2O_2$ caused increase of effluent COD, since analyzing agent, dichromate, reacted with $H_2O_2$ in the sample. Therefore, excess initial concentration of $H_2O_2$ would significantly affect effluent COD measurement. At pH variation experiment, both residual $H_2O_2$ and color showed peak in the neutral pH range with the same pattern. Effect of $H_2O_2$ dose also enhanced color removal but raised residual $H_2O_2$ problem in the continuous operation UV system. In conclusion, these results indicated that medium pressure UV/$H_2O_2$ system could be used to control color in the secondary effluent for reclamation and reuse.

• Journal of the Korean Chemical Society
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• 제31권4호
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• pp.359-363
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• 1987

Sonic waves (50KHz) was accelerated the oxidation reaction of primary, benzyl and secondary alcohol with $BaMnO_4\;and\;KMnO_4-CuSO_4{\cdot}5H_2O$ to give the corresponding aldehyde and ketone at $30^{\circ}C/1$ atm. in high yields compared to stirring or refluxing condition.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.3009-3016
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• 2012

This study evaluated the use of iron-impregnated SBA-15 (Fe/SBA-15) as a catalyst for the oxidative degradation of persistent phenol analogues, such as 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2,4,6-trichlorophenol (2,4,6-TCP) in water. The oxidation reactions were carried out with reaction time, concentration of the phenols, amount of the catalysts, reaction temperature, pH of the reaction mixture as the process variables with or without using hydrogen peroxide as the oxidizing agent. The conversion achieved with Fe/SBA-15 at 353 K for 2-CP, 4-CP, 2-NP, 4-NP, 2,4,6-TCP was 80.2, 71.2, 53.1, 62.8, 77.3% in 5h with a reactant to $H_2O_2$ mole ratio of 1:1, and 85.7, 65.8, 61.9, 63.7, 78.1% in the absence of $H_2O_2$, respectively. The reactions followed pseudo first order kinetics. The leachability study indicated that the catalyst released very little iron into water and therefore, the possibility of secondary pollution is negligible.

• Journal of the Korean Society for Precision Engineering
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• 제27권1호
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• pp.33-40
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• 2010

In this research, the effects for surface Improvement of plasma ion implanted carbide endmill tools were observed by measuring cutting forces and tools wear affecting surface roughness in high speed cutting. From the 2nd ion mass analysis, the oxidation layer was found to be built up by sputtering. The residual gas contamination of oxygen was found to be contained impurities in nitrogen gas. The plasma implanted ion was found to be spreaded, especially the nitrogen was implanted up to 150nm depth as impressed voltage and ion implanting time. It is analyzed as bring surface improvement by spreading deeply forming oxidation on surface. The factors in Analysis of Variance(ANOVA) about mutuality cause reference of cutting force. The cutting force Fx is affected by the interaction of spindle rpm and federate, the cutting force Fy is influenced by spindle rpm and time injected ion, and cutting force Fz is affected by the interaction of impressed voltage and feedrate. Also, it was found that the cutting forces of implanted tools become lower and the surface roughness is improved by the effect of nitrogen according to the implantation.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.149-156
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• 2006

Structure of edge flame established in a mixing layer, formed between two uniformly flowing pure $CH_4$ and pure $O_2$ streams, is numerically investigated by employing a detailed methane-oxidation mechanism. The numerical results exhibited the most outstanding distinction of using pure oxygen in the fuel-rich premixed-flame front, through which the carbon-containing compound is found to leak mainly in the form of CO instead of HC compounds, contrary to the rich $CH_4-air$ premixed flames in which $CH_4$ as well as $C_2H_m$ leakage can occur. Moreover, while passing through the rich premixed flame, a major route for CO production, in addition to the direct $CH_4$ decomposition, is found to be $C_2H_m$ compound formation followed by their decomposition into CO. Beyond the rich premixed flame front, CO is further oxidized into $CO_2$ in a broad diffusion-flame-like reaction zone located around moderately fuel-rich side of the stoichiometric mixture by the OH radical from the fuel-lean premixed-flame front. Since the secondary CO production through $C_2H_m$ decomposition has a relatively strong reaction intensity, an additional heat-release branch appears and the resulting heat-release profile can no longer be seen as a tribrachial structure.

• Journal of the Korean Society of Combustion
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• 제11권1호
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• pp.19-26
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• 2006

Structure of edge flame established in a mixing layer, formed between two uniformly flowing pure $CH_4$ and pure $O_2$ streams, is numerically investigated by employing a detailed methane-oxidation mechanism. The numerical results exhibited the most outstanding distinction of using pure oxygen in the fuel-rich premixed-flame front, through which the carbon-containing compound is found to leak mainly in the form of CO instead of HC compounds, contrary to the rich $CH_4-air$ premixed flames in which $CH_4$ as well as $C_2H_m$ leakage can occur. Moreover, while passing through the rich premixed flame, a major route for CO production, in addition to the direct $CH_4$ decomposition, is found to be $C_2H_m$ compound formation followed by their decomposition into CO. Beyond the rich premixed flame front, CO is further oxidized into $CO_2$ in a broad diffusion-flame-like reaction zone located around moderately fuel-rich side of the stoichiometric mixture by the OH radical from the fuel-lean premixed-flame front. Since the secondary CO production through $C_2H_m$ decomposition has a relatively strong reaction intensity, an additional heat-release branch appears and the resulting heat-release profile can no longer be seen as a tribrachial structure.

• Journal of the Korean Chemical Society
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• 제34권6호
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• pp.534-538
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• 1990

Chromium(Ⅵ) compound, [$C_9H_7$NH]$_2Cr_2O_7$ has been prepared by the reaction of isoquinoline with chromium trioxide under the presence of water. [$C_9H_7$NH]$_2Cr_2O_7$ is nonhydroscopic and dissolved in water very well. Structure of [$C_9H_7$NH]$_2Cr_2O_7$ is identified by FTIR spectra and elemental analysis data. The ability of [$C_9H_7$NH]$_2Cr_2O_7$ for the oxidation of alcohols were examined in methylene chloride. [$C_9H_7$NH]$_2Cr_2O_7$ was found as efficient oxidizing agent for the conversion of allyl, primary and secondary alcohols to the corresponding aldehydes or ketones.