• Current Optics and Photonics
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• v.2 no.3
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• pp.261-268
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• 2018

Stimulated polariton scattering (SPS) from the $A_1$ transverse optical (TO) modes of $BaTiO_3$ bulk crystal generating a terahertz (THz) wave with the noncollinear phase-matching (NPM) condition is theoretically investigated. To our best knowledge, this is the first report on THz wave generation from $BaTiO_3$ bulk crystal via SPS. Phase-matching (PM) characteristics in the NPM configuration are analyzed. Effective parametric gain lengths for the Stokes and THz waves in the NPM configuration are calculated. The effective parametric gain coefficient and absorption coefficient of the THz wave in $BaTiO_3$ are theoretically simulated. The THz phonon flux densities generated via SPS in $BaTiO_3$ are theoretically calculated by solving the coupled wave equations under the NPM condition. The PM characteristics and THz-wave parametric gain characteristics in $BaTiO_3$ are compared to those in $MgO:LiNbO_3$. The results of the analysis indicate that $BaTiO_3$ is an attractive optical crystal for efficient THz wave generation via SPS.

• New & Renewable Energy
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• v.4 no.1
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• pp.37-43
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• 2008

As the distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation units would be interconnected to the existing grids. This paper describes the results for the mechanical and environmental tests of pretreatment system material. Mechanical Characteristics make differences between parent / weldment, Notch existence / non-existence and air/$H_2O$ conditions. As a result, the life of pipe lines needs to maintain and fit for the operating period. Based on actual situations, the tension test of pipe welding-parts is carried out varying the exposure time of hydrogen sulfide and the fatigue resistance test is also performed inserting a notch into the pipe welding part, being exposed to the hydrogen sulfide environment for 720 hours.

• Clean Technology
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• v.24 no.3
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• pp.212-220
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• 2018

Oxy-fuel combustion is considered as a promising greenhouse gas reduction technology in power plant. In this study, the behaviors of NO and $SO_2$ were investigated under the condition that in-furnace $deNO_x$ and $deSO_x$ methods are applied in oxy-fuel circulating fluidized bed combustion condition. In addition, the generation trends of $SO_3$, $NH_3$ and $N_2O$ were observed. For the purpose, limestone and urea solution were directly injected into the circulating fluidized bed combustor. The in-furnace $deSO_x$ method using limestone could reduce the $SO_2$ concentration in exhaust gas from ~403 to ~41 ppm. At the same experimental condition, the $SO_3$ concentration in exhaust gas was also reduced from ~3.9 to ~1.4 ppm. This trend is mainly due to the reduction of $SO_2$. The $SO_2$ is the main source of the formation of $SO_3$. The negative effect of $CaCO_3$ in limestone, however, was also appeared that it promotes the NO generation. The NO concentration in exhaust gas reduced to ~26 - 34 ppm by appling selective non-catalytic reduction method using urea solution. The $NH_3$ concentration in exhaust gas was appeared up to ~1.8 ppm during injection of urea solution. At the same time, the $N_2O$ generation also increased with increase of urea solution injection. It seems that the HNCO generated from pyrolysis of urea converted into $N_2O$ in combustion atmosphere. From the results in this study, the generation of other pollutants should be checked as the in-furnace $deNO_x$ and $deSO_x$ methods are applied.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.56-62
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• 2016

A heterogeneous $Bi_2S_3/TiO_2$ composite catalyst was synthesized via a green ultrasonic-assisted method and characterized by XRD, SEM, EDX, TEM analysis. The results clearly show that the $TiO_2$ particles were homogenously coated with $Bi_2S_3$ particles, indicating that $Bi_2S_3$ particle agglomeration was effectively inhibited after the introduction of anatase $TiO_2$. The Texbrite BA-L (TBA) degradation rate constant for $Bi_2S_3/TiO_2$ composites reached $8.27{\times}10^{-3}min^{-1}$ under visible light, much higher than the corresponding value of $1.04{\times}10^{-3}min^{-1}$ for $TiO_2$. The quantities of generated hydroxyl radicals can be analyzed by DPCI degradation, which shows that under visible light irradiation, more electron-hole pairs can be generated. Finally, the possible mechanism for the generation of reactive oxygen species under visible-light irradiation was proposed as well. Our result shows the significant potential of $Bi_2S_3$-semiconductor-based $TiO_2$ hybrid materials as catalysts under visible light for the degradation of industry dye effluent substances.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.86-92
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• 2012

A characteristic study of chlorine dioxide generation by the electrolysis system was performed after chlorite ($ClO_2^-$) is adsorbed from sodium chlorite by a polymer ion exchange resin. A strongly basic anion exchange resin was used and a Ti plate coated with Ru and Ir was used as an electrode. Various parameters such as reaction stirring velocity, reaction temperature, chlorine dioxide product concentration, ion exchange resin content and product maker type for the adsorption quantity in the chlorite adsorption of ion exchange resin were investigated and found the ion exchange resin with the maximum adsorption quantity. A generation trend of chlorine dioxide was observed by the electrolysis system and optimum conditions on the desired value were found using response surface design of DOE (Design of Experiments). The strongly basic anion exchange resin with the maximum adsorption quantity was SAR-20 (TRILITE Gel type II) and the adsorption quantity was around 110 mg/IER (g). Observed generation optimum conditions of chlorine dioxide were constant-current (electrode area base; $A/dm^2$) and flow rate of $N_2$ gas (4.7 L/min) at the desired value of sterilization (900~1000 ppm, 1 h).

• Journal of Pharmacopuncture
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• v.19 no.1
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• pp.59-69
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• 2016

Objectives: The mushroom Ganoderma lucidum has been widely used as a traditional herbal medicine for many years. Although several studies have focused on the anti-oxidative activity of this mushroom, the molecular mechanisms underlying its activity have not yet been clearly established. The present study investigated the cytoprotective effect of ethanol extract of Ganoderma lucidum (EGL) against oxidative stress (hydrogen peroxide, $H_2O_2$) and elucidated the underlying mechanisms in a C2C12 myoblast cell line. Methods: Oxidative stress markers were determined by using the comet assay to measure reactive oxygen species (ROS) generation and deoxyribonucleic acid (DNA) damage. Cell viability and Western blotting analyses were employed to evaluate the cellular response to EGL and $H_2O_2$ in C2C12 cells. Transfection with nuclear factor erythroid 2-related factor 2 (Nrf2)-specific small interfering ribonucleic acid (siRNA) was conducted to understand the relationship between Nrf2 expression and $H_2O_2$-induced growth inhibition. Results: The results showed that EGL effectively inhibited $H_2O_2$-induced growth and the generation of ROS. EGL markedly suppressed $H_2O_2$-induced comet-like DNA formation and phosphorylation of histone H2AX at serine 139 ($p-{\gamma}H2AX$), a widely used marker of DNA damage, suggesting that EGL prevented $H_2O_2$-induced DNA damage. Furthermore, the EGL treatment effectively induced the expression of Nrf2, as well as heme oxygenase-1 (HO-1), with parallel phosphorylation and nuclear translocation of Nrf2 in the C2C12 myoblasts. However, zinc protoporphyrin IX, a HO-1 inhibitor, significantly abolished the protective effects of EGL against $H_2O_2$-induced accumulation of ROS and reduced cell growth. Notably, transient transfection with Nrf2-specific siRNA attenuated the cytoprotective effects and HO-1 induction by EGL, indicating that EGL induced the expression of HO-1 in an Nrf2-dependent manner. Conclusion: Collectively, these results demonstrate that EGL augments the cellular anti-oxidant defense capacity through activation of Nrf2/HO-1, thereby protecting C2C12 myoblasts from $H_2O_2$-induced oxidative cytotoxicity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.529-532
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• 2002

We experimentally investigate the evolution of nanosecond Stokes pulses in a single-pass Raman laser pumped by a Q-switched Nd: YAG laser at 1064 nm. As a Raman medium, a GeO$_2$-doped graded-index multimode fiber of 220m long is used. We demonstrate that efficient generation of several Stokes components with 1.5-2.7 nanosecond pulsewidth is obtained by varying the input pump energy.

• Tribology and Lubricants
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• v.15 no.1
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• pp.39-45
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• 1999

The wear behavior of $Al_2$O$_3$-40%TiO$_2$deposited on casted aluminum alloy (ASTM A356) by APS (Air Plasma Spray) against SiC ball has been investigated in this work. Wear tests were carried out at room temperature. The friction coefficient of $Al_2$O$_3$-40%TiO$_2$coating is lower than that of pure $Al_2$O$_3$coating(APS). $Al_2$O$_3$-40%TiO$_2$coating indicated the existence of the optimal coating thickness. It is found that voids and pores of coating surface resulted in the generation of cracks, and the cohesive of splats and the porosity of surface play a role in wear characteristics. It is suggested that the mismatch of thermal expansion of substrate and coating play an important role in wear performance. Tension and compression under thermo-mechanical stress may be occurred by the mismatch between thermal expansion of substrate and coating. The crack propagation above interface is observed in SEM.

• Journal of Animal Environmental Science
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• v.13 no.1
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• pp.1-12
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• 2007

Stored animal manure is considered as a significant agricultural source of methane $(CH_4)$ and nitrous oxide $(N_2O)$ which have 23 and 297 times higher global warming effect when compared to carbon dioxide $(CO_2)$. Uncertainties caused by lack of understanding physical and biochemical environment in stored animal manure and by errors of emission measurement methods, even though many researches measuring $CH_4\;and\;N_2O$ emissions from stored manure have been conducted for a few decades. In this paper, general information of $CH_4\;and\;N_2O$ generation and emissions from stored animal manure and the measurement methods for quantifying $CH_4\;and\;N_2O$ emissions are discussed.

• Journal of Soil and Groundwater Environment
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• v.6 no.1
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• pp.3-12
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• 2001

During ozonation process, the hydroxyl radical generation rates were measured under different experimental conditions (ozone feed rate, nitrobenzene concentration, hydroxyl radical scavenger, pH, HO$_2$O$_2$/O$_3$ etc.) Nitrobenzene could be decomposed by hydroxyl radical rather than ozone only and nitrobenzene decomposition rate was expressed with functions of ozone and nitrobenzene concentration. The rate was decreased as the hydroxyl radical scavenger concentration was increased, and all results were followed pseudo first-order reaction. Using a competitive method, hydroxyl radical generation rate was measured with probe compound and scavenger. It was proportional to ozone concentration, and 0.24mo1 of hydroxyl radical was produced with 1mol of ozone. Under different pH conditions, hydroxyl radical generation rates were measured (pH 10.2 (0.91Ms$^{-1}$ ) > pH 7.3 (0.72Ms$^{-1}$ ) > pH 5.6 (0.67Ms$^{-1}$ ) > pH 3.4 (0.63Ms$^{-1}$ )) showing higher generation rate at high pH values. Addition of hydrogen peroxide promoted the generation rate of hydroxyl radical. Considering the results of pH experiments and addition of hydrogen peroxide experiments, the hydroxyl radical generation rate was 1.6 times higher in hydrogen peroxide solution than in high pH solution, indicating addition of hydrogen peroxide is better promoter to produce the hydroxyl radical in ozonation. These results could be applied to AOPs to remediate the contaminated wastewater and groundwater.