• Journal of Korean Society of Water and Wastewater
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• v.33 no.4
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• pp.243-250
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• 2019

This objective of this study was to investigate the degradation characteristics of phenol, a refractory substance, by using a submerged dielectric barrier discharge (DBD) plasma reactor. To indirectly determine the concentration of active species produced in the DBD plasma, the dissolved ozone was measured. To investigate the phenol degradation characteristics, the phenol and chemical oxygen demand (COD) concentrations were evaluated based on pH and the discharge power. The dissolved ozone was measured based on the air flow rate and power discharged. The highest dissolved ozone concentration was recorded when the injected air flow rate was 5 L/min. At a discharge power of 40W as compared to 70W, the dissolved ozone was approximately 2.7 - 6.5 times higher. In regards to phenol degradation, the final degradation rate was highest at about 74.06%, when the initial pH was 10. At a discharged power of 40W, the rate of phenol decomposition was observed to be approximately 1.25 times higher compared to when the discharged power was 70W. It was established that the phenol degradation reaction was a primary reaction, and when the discharge power was 40W as opposed to 70W, the reaction rate constant(k) was approximately 1.72 times higher.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.11
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• pp.1985-1994
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• 2000

This research was designed to investigate the effect of initial adsorbed amount of phenol, temperature, and pH on the desorption reaction of phenol from spent activated carbon loaded with phenol. Methanol, acetone, and N,N-dimethylformamide( DMF) were used as test organic solvents. The initial adsorbed quantities of phenol investigated here were 166.1mg/g, 180.7mg/g, and 197.9mg/g. The effect of temperature was evaluated from 15 to $55^{\circ}C$ with an interval of $10^{\circ}C$, while that of pH was investigated under acidic. neutral. and alkaline conditions. The extent of phenol desorption was proportional to the strength of dipole moment such as methanol < acetone < DMF. Over 90% desorption of phenol was achieved by acetone and DMF. The quantity of des orbed phenol by the organic solvents decreases with increasing the initial adsorbed amount of phenol. DMF is affected least by the initially adsorbed amount of phenol. An increase in reaction temperature leads to higher desorption of phenol. Desorption reaction by methanol is most sensitive to the temperature. As the pH of solvents increases. the desorption rate is also increasing. At pH=12. the desorption rate of phenol by methanol increases sharply by 10%. Although methanol demonstrated the weakest desorption power. the desorption capacity of methanol would approach that of acetone and DMF by adjusting temperature and pH. Methanol may emerge as a promising solvent for removing phenol from activated carbon because of acceptable regeneration efficiency as well as relatively cheap price.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.5-12
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• 2011

This study was focused on the reactivity of furnace slag against cadmium to design the vertical drain method with reactive column for improving contaminated sea shore sediment. The kinetic sorption test was performed by changing the initial concentration and pH. Using pseudo-second-order model, the reactivity of furnace slag was quantitatively analyzed. Equilibrium removal amount ($q_e$) of furnace slag increased and rate constant ($k_2$) decreased with the increase of initial cadmium concentration. With the increase of pH, the equilibrium removal amount ($q_e$) and rate constant ($k_2$) increased in the same initial concentration. Required retention time was related to the inverse of the product of the equilibrium removal amount ($q_e$) multiplied by rate constant ($k_2$). The required retention time could be used to design the length of reactive column.

• Microbiology and Biotechnology Letters
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• v.22 no.3
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• pp.296-303
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• 1994

An immobilized Trigonopsis variabilis cells having an high activity of D-amino acid oxidase(DAO) was used to convert CPC into GL-7-ACA. The optimal pH of the reaction system was 8.0-8.5, and the optimal temperature was 40$\circ$C. When immobilized cell was used repeatedly in semi-batchwise reaction, the system retained 80% of the initial activity after used of 12 times for over 12 hours. The storage stability of the immobilized cell was maintained for 30 days at 4$\circ$C. The CPC concentration for the maximal reaction rate was about 30 mM and 40 mM for free and immobilized cells, respectively. Substrate inhibition of CPC concentration more than 50 mM was overcomed by 20~25% by immobilization. Pure oxygen supply into reaction system was most efficient in D-amino acid oxidase reaction. Continuous conversion to GL-7-ACA from CPC has been developed with an bioreactor system containing immobilized T variabilis cells. By opera- tion of the reactor for 5 hours, the average conversion yield of >80% and GL-7-ACA production of 40~45 mM per hour could be obtained.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.9-18
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• 2006

These studies show that I applied to functional insole (a specific S 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 $2.0{\pm}0.24$ meter per second by motion analysis, ground reaction force and electromyography 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. Second, Contact time, Vertical impact force peak timing, Vertical active force and Active force timing, and Maximum loading rate under impulse of first 20 percent and Value of total impulse caused Ground reaction force. Third. The tendon fo Quadriceps femoris, Biceps femoris, Tibialis anterior and gastronemius medials caused. electromyography. 1. 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). 2 Electromyography showed that averagely was distinguished from other factors, and did not show about that. 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.

• Environmental Engineering Research
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• v.10 no.4
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• pp.174-180
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• 2005

Nano-sized iron was synthesized using borohydride reduction of $Fe^{3+}$ in aqueous solution. A wide range of synthesis conditions including varying concentrations of reagents, reagent feeding rate, and solution pH was applied in an aqueous system under anaerobic condition. The reactivity of nano-sized iron from each synthesis was evaluated by reacting the iron with TCE in batch systems. Evidence obtained from this study suggest the reactivity of iron is strongly dependent on the synthesis solution pH. The iron reactivity increased as solution pH decreased. More rapid TCE reduction was observed for iron samples synthesized from higher initial $Fe^{3+}$ concentration, which resulted in lower solution pH during the synthesis reaction. Faster feeding of $BH_4^-$ solution to the $Fe^{3+}$ solution resulted in lower synthesis solution pH and the resultant iron samples gave higher TCE reduction rate. Lowering the pH of the solution after completion of the synthesis reaction significantly increased reactivity of iron. It is presumed that the increase in the reactivity of iron synthesized at lower pH is due to less precipitation of iron (hydr)oxides or less surface passivation of iron.

• Journal of Pharmaceutical Investigation
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• v.35 no.5
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• pp.333-336
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• 2005

The objective of this study was to investigate the stability of tetracycline HCl on encapsulation into and inside reverse micelles. To do so, tetracycline HCl was first mixed with cetyltrimethylammonium bromide, water and ethyl formate to make reverse micelles. The degradation kinetics of tetracycline HCl inside the reverse micelles was then assessed by scrutinizing its stability data. Under our experimental conditions, the reverse micelles formed spontaneously in absence of any mixing devices. During the preparation of the reverse micelles, however, considerable portions of tetracycline HCl underwent a chemical reaction (e.g., epimerization). For instance, $51.4{\pm}0.6%$ of an initial concentration of tetracycline HCl was transformed into a degradation product. Once dissolved inside the reverse micelles, the degradation of tetracycline HCl followed an exponential decay pattern. The plot of log{the degradation rate of tetracycline HCl} versus log{tetracycline HCl concentration} made it possible to determine the order of degradation reaction and rate constant. It was proven that the degradation of tetracycline HCl inside the reverse micelles followed a first order kinetics with a rate constant of 0.0027 $hour^{-1}$. Meriting further investigation might be formulation studies to stabilize tetracycline HCl on encapsulation into and inside the reverse micelles.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.2
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• pp.89-94
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• 1999

In this study small glass columns with 2.5cm inner diameter and 24.5cm length were used as many as the sample numbers to study the effects of initial pH, temperature, dissolved oxygen concentration, and sediment depth on the release of phosphorus from lake sediment. No phosphorus release occurred at $10^{\circ}C$ with all pHs, and release rate at $25^{\circ}C$ was higher than that at $35^{\circ}C$ with pH 4 and reverse trends were observed at pH 7 and 10. Under all conditions, DO concentrations were decreased and equilibrium was obtained after 4-8 days when phosphorus release started and the Do concentrations were less than 1 mg/l. Sediment depth had little effect on phosphorus release rate. It was found that relation between released SRP(Soluble Reactive Phosphorus) concentration and time was zero order reaction and reaction rate coefficients were obtained. The amount of phosphorus release from lake sediment can be predicted by considering these k values.

• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1149-1153
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• 2002

CH4/CO2 dry reforming was carried out to make syn gas on the Ni/Al2O3 catalysts calcined at different temperatures. The Ni/Al2O3 (850 $^{\circ}C)$ catalyst gave good activity and stability w hereas the Ni/Al2O3 $(450^{\circ}C)$ catalyst showed lower activity and stability. The NiO/Al2O3 catalyst calcined at $850^{\circ}C$ for 16 h (Ni/Al2O3 $(850^{\circ}C))$ formed the spinel structure of nickel aluminate, which was confirmed by TPR. The carbon formation rate on the Ni/Al2O3 $(850^{\circ}C)$ catalyst was very low till 20 h, and then steeply increased with reaction time without decreasing the activity for CH4 reforming. The Ni/Al2O3 $(450^{\circ}C)$ catalyst showed high carbon formation rate at the initial reaction time and then, the rate nearly stopped with continuous decreasing the activity for CH4 reforming. Even though the amount of carbon deposition on the Ni/Al2O3 $(850^{\circ}C)$ catalyst was higher than that on the Ni/Al2O3 $(450^{\circ}C)$ catalyst, the activity for CH4ing was also high, which could be attributed to the different type of the carbon formed on the catalyst surface.

• Korean Journal of Food Science and Technology
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• v.19 no.2
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• pp.113-118
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• 1987

An intermediate moisture model food system was used to investigate the effects of water activity (Aw), temperature, pH and polyethyleneglycol (PEG) on the Maillard reaction. The initial molar ratio of glucose to lysine was varied from one half to four. The maximum Maillard reaction was obtained from an initial glucose/lysine molar ratio of approximately three. The rate of Maillard reaction showed a maximum in the range of water activity of a normal intermediate moisture food. 'the model food system was prepared to hold water activity range of 0.47-0.84 and the samples were held at various temperatures. The maximum browning rate occurred at an Aw value of approximately 0.89 at $40^{\circ}C$ and $60^{\circ}C$, 0.74 at $30^{\circ}C$ and 0.67 at $20^{\circ}C$, respectively. The Arrhenius activiation energies for nonenzymatic browning pigment production were 18.03, 15.18 and 9.90 Kcal/mole for the sample with Aw 0.84, 0.74 and 0.67. When the pH of the model system was increased, a significant increase in the browning reaction was observed. On the inhibitive effects of PEG, the higher degree of polymerization, the more inhibition of browning reaction.