• Journal of Energy Engineering
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• v.25 no.4
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• pp.152-158
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• 2016

Nitrogen oxide is generated by the chemical reaction of oxygen and nitrogen in higher temperature environment of combustion facilities. The NOx reduction equipment is generally used in the power plant or incineration plant and it causes enormous cost for the construction and maintenance. The flue gas recirculation method is commonly adopted for the reduction of NOx formation in the combustion facilities. In the present study, the computational fluid dynamic analysis was accomplished to elucidated the cold flow characteristics in the flue gas recirculation burner with coanda nozzles in the flue gas recirculation pipe. The inlet and outlet of flue gas recirculation pipes are directed toward the tangential direction of circular burner not toward the center of burner. The swirling flow is formed in the burner and it causes the reverse flow in the burner. The ratio of flue gas recirculation flow rate with the air flow rate was about 2.5 for the case with the coanda nozzle gap, 0.5mm and it was 1.5 for the case with the gap, 1.0mm. With the same coanda nozzle gap, the flue gas recirculation flow rate ratio had a little increase when the air flow rate changes from 1.1 to 2.2 times of ideal air flow rate.

• The Korean Journal of Pharmacology
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• v.24 no.1
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• pp.53-61
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• 1988

The effect of antioxidants on the myocardial cellular damage which occurs during reoxygenation of hypoxic myocardium was examined in isolated rat hearts. The roles of oxygen free radical and lipid peroxidation in reoxygenation injury of myocardium were also investigated. In Langenorff preparation of isolated rat heart, which was made hypoxic by perfusion with the substrate free, hypoxic cardioplegic solution ($37^{\circ}C$, 90 min), the release of cytosolic enzymes (creatine phosphokinase, lactic dehydrogenase) and a lipid peroxidation product, malondialdehyde into the coronary effluent were abruptly increased by reoxygenation. The release of enzymes was closely parallel to that of MDA. These increases of enzymes and lipid peroxidation product were suppressed to various degrees in the presence of scavengers of superoxide anion (superoxide dismutase, 10,000 U), hydrogen peroxide (catalase, 25,000 U) and hydroxyl radical (dimethyl sulfoxide, 10%). A natural antioxidant, ${\alpha}-tocopherol$(4.5 uM) and a synthetic one, butylated hydroxytoluene (2 uM) suppressed the release of cytosolic enzymes with the concomittent reduction of lipid peroxidation as measured by malondialdehyde release into the coronary effluent. These effects of antioxidants were dose dependent, and were more pronounced when the antioxidants were administered throughout hypoxic and reoxygenation periods than given during reoxygenation period only. These results suggest that cytotoxic oxygen free radicals produced in the myocardium during reoxygenation may be responsible fur the myocardial cellular injury by enhancing the lipid peroxidation of cellular membranes. Furthermore, the antioxidants may exert protective effect against reoxygenation damage of hypoxic myocardium through the inhibition of lipid peroxidation reaction.

• Journal of Life Science
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• v.28 no.9
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• pp.1016-1021
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• 2018

Clostridium difficile toxin A causes pseudomembranous colitis. The pathogenesis of toxin A-induced colonic inflammation includes toxin A-dependent epithelial cell apoptosis, resulting in the loss of barrier function provided by epithelial cells against luminal pathogens. Toxin A-dependent epithelial cell apoptosis has been linked to toxin A-induced production of reaction oxygen species and subsequent p38MAPK activation; $p21^{CIP1/WAF1}$ upregulation-dependent cell cycle arrest; cytoskeletal disaggregation; and/or the induction of Fas ligand on epithelial cells. However, the molecular mechanisms underlying toxin A-induced apoptosis remain poorly understood. This study tested whether toxin A could block the Wnt signaling pathway, which is involved in gut epithelial cell proliferation, differentiation and antiapoptotic progression. Toxin A treatment of nontransformed human colonocytes (NCM460) rapidly reduced ${\beta}$-catenin protein, an essential component of the Wnt signaling pathway. Exposure of mouse ileum to toxin A also significantly reduced ${\beta}$-catenin protein levels. MG132 inhibition of proteasome-dependent protein degradation resulted in the recovery of toxin A-mediated reduction of ${\beta}$-catenin, indicating that toxin A may activate intracellular processes, such as $GSK3{\beta}$, to promote degradation of ${\beta}$-catenin. Immunoblot analysis showed that toxin A increased active phosphorylation of $GSK3{\beta}$. Because the Wnt signaling pathway is essential for gut epithelial cell proliferation and anti-apoptotic processes, our results suggest that toxin A-mediated inhibition of the Wnt signaling pathway may be required for maximal toxin A-induced apoptosis of gut epithelial cells.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.88-94
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• 2012

One of the effective ways to reduce both $NO_x$ and PM at the same time in a diesel CI engine is to operate the engine in low temperature combustion (LTC) regimes. In general, two strategies are used to realize the LTC operation-dilution controlled LTC and late injection LTC - and in this study, the former approach was used. In the dilution controlled regime, LTC is achieved by supplying a large amount of EGR to the cylinder. The significant EGR gas increases the heat capacity of in-cylinder charge mixture while decreasing oxygen concentration of the charge, activating low temperature oxidation reaction and lowering PM and $NO_x$ emissions. However, use of high EGR levels also deteriorates combustion efficiency and engine power output. Therefore, it is widely considered to use increased intake pressure as a way to resolve this issue. In this study, the effects of intake pressure variations on performance and emission characteristics of a single cylinder diesel engine operated in LTC regimes were examined. LTC operation was achieved in less than 8% $O_2$ concentration and thus a simultaneous reduction of both PM and $NO_x$ emission was confirmed. As intake pressure increased, combustion efficiency was improved so that THC and CO emissions were decreased. A shift of the peak Soot location was also observed to lower $O_2$ concentration while $NO_x$ levels were kept nearly zero. In addition, an elevation of intake pressure enhanced engine power output as well as indicated thermal efficiency in LTC regimes. All these results suggested that LTC operation range can be extended and emissions can be further reduced by adjusting intake pressure.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.2
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• pp.47-52
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• 2015

A microbial fuel cell (MFC) is a device that can be obtained electricity from a variety of organic through the catalytic reaction of the microorganism. The MFC can be applied to various fields, and research is required to promote the performance of the microbial fuel cell for commercialization. The lower performance of an MFC is due to oxygen reduction at the cathode and the longer time of microbial degradation at anode. The MFC amount of power is sufficient but, in consideration of many factors, as a renewable energy, now commonly power density as compared to Nafion117 it is an ion exchange membrane used is PP (Poly Propylene) from 80 to about 11 fold higher, while reducing the cost to process wastewater is changed to a microporous non-woven fabric of a low cost, it may be energy-friendly environment to generate electricity. All waste, in that it can act as a bait for microorganisms, sustainability of the microbial fuel cell is limitless. The latest research on the optimization and performance of the operating parameters are surveyed and through the SSaM-GG(Smart, Shared, and Mutual- Green Growth) or GG-SSaM(Green Growth - Smart, Shared, and Mutual) as the concept of sustainable development in MFC, the middle indices are developed in this study.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.4
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• pp.175-180
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• 2011

The doping effect of Cu in the Sr-doped lanthan manganites (LSM) has been investigated in terms of structural analysis and thermal expansion coefficient (TEC). The $La_{0.8}Sr_{0.2}Mn_{1-x}Cu_xO_3$ ($0{\leq}x{\leq}0.3$) were prepared by solid state reaction method and their crystal structure and TEC were measured. A decrease in the lattice parameters and the TEC were observed with increase eu content, whereas they were decreased for x = 0.3. For $0{\leq}x{\leq}0.2$, the decrease of the lattice parameter and the TEC with increase Cu content were attributed to the reduction of ionic radius of Cu ions due to the presence of $Cu^{3+}$ ions. For x = 0.3, however, the increase was originated from the formation of oxygen vacancies due 10 the presence of $Cu^{2+}$ and $Mn^{4+}$.

• Journal of the Korean Electrochemical Society
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• v.11 no.4
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• pp.313-318
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• 2008

The influence of the particle size of platinum(Pt) on the stability and activity was studied. The particle size of platinum was controlled in the range of $3.5{\sim}9\;nm$ by heat treatment of commercial Pt/C and confirmed by XRD and TEM. An accelerated degradation test was performed to evaluate the stability of platinum catalysts. Oxygen reduction reaction was monitored for the measurement of activity. As increasing the Pt particle size, the stability of Pt/C electrode was enhanced and the activity was reduced. It was confirmed that the stability of Pt/C electrode was in inverse proportion to the activity. PtCo/C alloy catalyst was used to improve the activity and stability of large-sized platinum particle. The maximum power density of commercial Pt/C was $507.6\;mV/cm^2$ and PtCo/C alloy catalyst was $585.8\;mV/cm^2$. The decrement of electrochemical surface area showed Pt/C(60%) and PtCo/C alloy catalyst(24%). It was possible to enhance both of stability and activity of catalyst by the combination of particle size control and alloying.

• Journal of dental hygiene science
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• v.13 no.3
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• pp.321-329
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• 2013

Although it has been reported that lysyl oxidase (LOX) is involved in odontoblastic differentiation, the role of LOX on odontoblastic differentiation by hydrogen peroxide ($H_2O_2$) have not been clarified. In the present study, we investigated whether $H_2O_2$, reactive oxygen species (ROS), is modulated the messenger RNA (mRNA) expression and activity of LOX during odontoblastic differentiation of human dental pulp (HDP) cells. The mRNA expression was quantified by reverse transcriptase polymerase chain reaction (RT-PCR) analysis, and LOX enzyme activity was measured by high sensitive fluorescent assay. Expression of the odontoblastic differentiation marker genes were assessed in the presence and absence of specific small interfering RNAs (siRNAs) of the LOX and LOXL. The $H_2O_2$-induced mRNA expression of LOX family was significant reduction of LOX, LOXL, and LOXL3 mRNA levels in HDP cells. LOX enzyme activity was increased at $H_2O_2$ 0.3 mM for 24 hours. The mRNA expression of alkaline phosphatase (ALP), osteopontin (OPN), and osteocalcin (OCN) was inhibited by LOX- and LOXL-specific siRNAs whereas the mRNA expression of dentin matrix protein1 (DMP1), and dentin sialophosphoprotein (DSPP) was inhibited by LOX-specific siRNA. In LOX enzyme activity, siRNA-induced knockdown of both LOX and LOXL inhibited the total amine oxidase activity in HDP cells, as in the case of mRNA expression. In conclusion, the essential role of $H_2O_2$ on odontoblastic differentiation suggests that its regulation by LOX may have pharmacologic importance in HDP cells.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.35-41
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• 2021

VWTi, which is used as a commercial catalyst in NH3-SCR, exhibits excellent denitrification performance at 300 to 400 ℃, but there is a problem that efficiency decreases at low temperatures below 300 ℃. Research on catalysts containing promoter to increase low-temperature denitrification efficiency is steadily progressing. However, research on the cause of the improvement in low-temperature denitrification efficiency of the catalyst and the catalyst properties is insufficient. In this study, it was confirmed that by adding Sb to VWTi, denitrification performance was improved by more than 10% in NH3-SCR reaction below 300 ℃. At this time, the space velocity and the size of the catalyst particles were controlled to exclude the influence of external/internal diffusion. In addition, the catalytic properties according to the presence or absence of Sb were investigated by performing BET, TEM/EDS, O2-TPD, H2-TPR and DRIFTs analysis. It was judged that the addition of Sb increased the adsorbed oxygen species on the surface of the catalyst, thereby enhancing the redox properties of the catalyst at low temperature and exhibiting excellent denitrification performance.

• Journal of Life Science
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• v.25 no.7
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• pp.740-747
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• 2015

This study was carried out to evaluate changes in the meat quality and antioxidation activity in the loin and ham of Korean Native Black Pigs (KNBP) during frozen storage at −18℃ for 150 days. The pH value of the loin was decreased as storage days progressed, while the pH value of the ham showed no consistent changes with storage days. The lightness (L*) of the loin did not show any significant reduction until day 120, whereas L* of the ham was significantly declined throughout the storage period (p<0.05). The redness (a*) values of the loin and ham were significantly decreased as storage progressed. The water holding capacity of the loin was decreased by day 30 and that value was maintained until the end of storage. The initial total numbers of microorganisms in the loin and ham were 4.88 and 5.16 Log CFU/g, respectively and these numbers were significantly decreased by day 30 (p<0.05). The levels of 2-thiobarbituric acid reactive substances (a measurement of lipid oxidation) in the loin and ham ranged from 0.057-0.069 and 0.052-0.087 mg MDA/kg meat, respectively, until storage day 150. Volatile basic nitrogen values of the loin and ham ranged from 15.13-16.55 and 16.05-16.23 mg%. Oxygen radical absorbance capacities and carnosine contents of the loin and ham were significantly decreased during frozen storage for 3 months (p<0.05). In summary, the meat quality of the loin and ham from KNBP was somewhat decreased during frozen storage. However, the levels of antioxidants and dipeptides with antioxidant activity were significantly decreased in pork loin and ham during frozen storage.