• Journal of Electrochemical Science and Technology
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• v.5 no.2
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• pp.45-48
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• 2014

$TiO_2$ nanoparticles (NPs) with a diameter of 100 nm were synthesized by a simple hydrothermal route at $220^{\circ}C$ and then processed for a possible alternate cathode catalyst material in the lithium-oxygen batteries. It was found that when $TiO_2$ nanoparticles were utilized as cathodes, substantial improvements in the discharge capacity, cycle ability, rate capability and low overpotential were observed. This can be attributed to its high catalytic activity and large surface area.

• Journal of Electrochemical Science and Technology
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• v.5 no.4
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• pp.105-108
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• 2014

$TiO_2$ nanoparticles (NPs) with a diameter of 100 nm were synthesized by a simple hydrothermal route at $220^{\circ}C$ and then processed for a possible alternate cathode catalyst material in the lithium-oxygen batteries. It was found that when $TiO_2$ nanoparticles were utilized as cathodes, substantial improvements in the discharge capacity, cycle ability, rate capability and low overpotential were observed. This can be attributed to its high catalytic activity and large surface area.

• Molecules and Cells
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• v.39 no.1
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• pp.1-5
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• 2016

Peroxiredoxins (Prxs) are a very large and highly conserved family of peroxidases that reduce peroxides, with a conserved cysteine residue, designated the "peroxidatic" Cys ($C_P$) serving as the site of oxidation by peroxides (Hall et al., 2011; Rhee et al., 2012). Peroxides oxidize the $C_P$-SH to cysteine sulfenic acid ($C_P$-SOH), which then reacts with another cysteine residue, named the "resolving" Cys ($C_R$) to form a disulfide that is subsequently reduced by an appropriate electron donor to complete a catalytic cycle. This overview summarizes the status of studies on Prxs and relates the following 10 minireviews.

• Bulletin of the Korean Chemical Society
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• v.21 no.12
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• pp.1207-1212
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• 2000

The free energy simulation technique is used to evaluate the relative binding affinity of a set of hydroxyethylene isostere inhibitors of the HIV-1 protease. The binding reactions and an alchemical mutation construct the thermodynamic cycle, which reduces the free energy difference of the binding interactions into that of the alchemical processes. In the alchemical process, a methyl group is mutated into a hydrogen atom. Albeit the change is a small perturbation to the inhibitor-protease complex, it results in 25 fold difference in the binding constants. The simulation reproduces the experimentally measured binding affinities within 2% of the free energy difference. The protonation state of the catalytic aspartic acid residues is also investigated through the free energy simulations.

• Journal of Sensor Science and Technology
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• v.4 no.4
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• pp.16-22
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• 1995

Catalytic combustion type gas sensor was fabricated by using ${\gamma}-Al_{2}O_{3}$, Pd catalyst and some binders for metane and propane detection. Using the gas sensor, digital gas meter was manufactured and tested for sensing performance. The fabricated sensor had power consumption of 700mW with applied voltage of dc 2V and the output voltage of the sensor was about 700mV for propane of 1,000ppm and 500mV for methane of 1,000ppm. In 10 cycle injection of the gases of 2,400ppm, The digital meter showed good sensitivity, linearity, and reproductivity with precision of ${\pm}25ppm({\pm}1%)$.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.95-105
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• 2012

The selective catalytic reduction (SCR) system is a highly-effective aftertreatment device for NOx reduction of diesel engines. Generally, the ammonia ($NH_3$) was generated from reaction mechanism of SCR in the SCR system using the liquid urea as the reluctant. Therefore, the precise urea dosing control is a very important key for NOx and $NH_3$ slip reduction in the SCR system. This paper investigated NOx and $NH_3$ emission characteristics of urea-SCR dosing system based on model-based control algorithm in order to reduce NOx. In the map-based control algorithm, target amount of urea solution was determined by mass flow rate of exhaust gas obtained from engine rpm, torque and $O_2$ for feed-back control NOx concentration should be measured by NOx sensor. Moreover, this algorithm can not estimate $NH_3$ absorbed on the catalyst. Hence, the urea injection can be too rich or too lean. In this study, the model-based control algorithm was developed and evaluated on the numerical model describing physical and chemical phenomena in SCR system. One channel thermo-fluid model coupled with finely tuned chemical reaction model was applied to this control algorithm. The vehicle test was carried out by using map-based and model-based control algorithms in the NEDC mode in order to evaluate the performance of the model based control algorithm.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.206-214
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• 2005

Heterogeneously-catalyzed oxidation of aqueous phase trichloroethylene (TCE) over supported metal oxides has been conducted to establish an approach to eliminate ppm levels of organic compounds in water. A continuous flow reactor system was designed to effect predominant reaction parameters in determining catalytic activity of the catalysts for wet TCE decomposition as a model reaction. 5 wt.% $CoO_x/TiO_2$ catalyst exhibited a transient period in activity vs. on-stream time behavior, suggesting that the surface structure of the $CoO_x$ might be altered with on-stream hours; regardless, it is probable to be the most promising catalyst. Not only could the bare support be inactive for the wet decomposition reaction at $36^{\circ}C$, but no TCE removal also occurred by the process of adsorption on $TiO_2$ surface. The catalytic activity was independent of all particle sizes used, thereby representing no mass transfer limitation in intraparticle diffusion. Very low TCE conversion appeared for $TiO_2$-supported $NiO_x$ and $CrO_x$ catalysts. Wet oxidation performance of supported Cu and Fe catalysts, obtained through an incipient wetness and ion exchange technique, was dependent primarily on the kinds of the metal oxides, in addition to the acidic solid supports and the preparation routes. 5 wt.% $FeO_x/TiO_2$ catalyst gave no activity in the oxidation reaction at $36^{\circ}C$, while 1.2 wt.% Fe-MFI was active for the wet decomposition depending on time on-stream. The noticeable difference in activity of the both catalysts suggests that the Fe oxidation states involved to catalytic redox cycle during the course of reaction play a significant role in catalyzing the wet decomposition as well as in maintaining the time on-stream activity. Based on the results of different $CoO_x$ loadings and reaction temperatures for the decomposition reaction at $36^{\circ}C$ with $CoO_x/TiO_2$, the catalyst possessed an optimal $CoO_x$ amount at which higher reaction temperatures facilitated the catalytic TCE conversion. Small amounts of the active ingredient could be dissolved by acidic leaching but such a process gave no appreciable activity loss of the $CoO_x$ catalyst.

• The Journal of Internal Korean Medicine
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• v.28 no.4
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• pp.694-708
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• 2007

Objectives : Jageum-Jung is used as an anti-cancer agent in oriental medicine, but the mechanism by which it induces cell death in cancer cells is still unclear. The purpose of this study was to investigate the effects of Jageum-Jung on apoptosis and cell cycle arrest in HepG2 hepatoma cells. Methods : Various cancer cell lines including HepG2, C6 glioma, SH-SY5Y, PANC-1, and MCF-7 cells, were used. Apoptosis was determined by DAPI nuclei staining and flow cytometry in HepG2 cells treated with various concentrations (from 25 to 200 ${\mu}g/ml$) of $H_2O$ extract of Jageum-Jung (JGJ) for 48 hrs. Expression of cell cycle arrest mediators including Rb, p53, p21, cyclin B1, cdk4, and cyclin E proteins were measured by Western blot analysis. To estimate intracellular hydrogen peroxide levels and intracellular nitric oxide levels, HepG2 cells were stained with DCFH-DA dye and DAF dye, subjected on flow cytometric analysis. Results : 1. Jageum-Jung decreased the viability of HepG2 cells in a dose-dependent manner. 2. Jageum-Jung induced the catalytic activation of caspase-3 in HepG2 cells. 3. Jageum-Jung increased the intracellular hydrogen peroxide and NO in HepG2 cells. 4. Jageum-Jung increased the expression of Rb, p53 and p21 in HepG2 cells. 5. Jageum-Jung induced the expression of cyclin B1, cdk4, and cyclin E in HepG2 cells. Conclusions : Taken together, we suggest that Jageum-Jung exhibits cytotoxic effects on HepG2 cells, causing apoptosis and cell cycle arrest. The results showed that Jageum-Jung may do so by regulating the expression of specific target molecules that promote efficient apoptotic cell death following $G_2$/M phase arrest in a dose-dependent manner.

• Resources Recycling
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• v.32 no.3
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• pp.45-56
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• 2023

This study analyzed the economic and environmental effect of recycling rhodium used in the non-catalytic field. As an analysis methodology, economic effect analysis applied cost-benefit analysis and resource-saving effect analysis and the environmental effect analysis applied life cycle assessment (LCA). The results show that from an economic point of view, the cost-benefit ratio was 1.28, which was feasible, and the cost reduction was 237,000 won based on 1 g of rhodium recycled and the amount of rhodium recycled was 7.17 billion won in 2025. As for the environmental effect, the greenhouse gas(GHG) emissions were compared between the case of recycling based on rhodium 1 kg and the case of overseas sales. The calculation results show that based on rhodium 1 kg, greenhouse gas emissions were reduced by 99.8%, from 65 kg CO₂eq./kg-Rh when recycling to 28,800 kg CO₂eq. when sold overseas. The results obtained from this study could suggest that rhodium recycling is necessary in Korea where resources are scarce by analyzing the economic and environmental effect of recycling rhodium used in the non-catalytic field.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.4
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• pp.411-420
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• 2018

This study presents a revised crackling core model for the description of $UO_2$ sphere oxidation in air atmosphere. For close reproduction of the sigmoid behavior exhibited in $UO_2$ to $U_3O_8$ conversion, the fragmentation effect contributing to the increased reactive surface area and the concept of variable grain conversion time were considered in the model development. Under the assumptions of two-step successive reaction of $UO_2{\rightarrow}U_3O_7{\rightarrow}U_3O_8$ and final grain conversion time equivalent to ten times the initial grain conversion time, the revised model showed good agreement with the experimental data measured at 599 - 674 K and a lowest deviation when compared with Nucleation and Growth model and AutoCatalytic Reaction model. The evaluated activation energy at 100% conversion to $U_3O_8$, $57.6kJ{\cdot}mol^{-1}$, was found to be closer to the experimentally extrapolated value than to the value determined in AutoCatalytic Reaction model, $48.6kJ{\cdot}mol^{-1}$.