• Journal of Hydrogen and New Energy
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• v.22 no.5
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• pp.609-615
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• 2011

A 5 kW class SOFC system for cogeneration power units was consisted of a hot box part and cold BOPs. High temperature components such as a stack, a fuel reformer, a catalytic combustor, and heat exchanges are arranged in the bot box considering their operating temperatures for the system efficiency. The hot box was made of ceramic boards for the thermal insulation. A 5 kW class SOFC stack was composed of 2 sub-modules and each module had 64 cells with $15{\times}15cm^2$ area and stainless steel interconnects. The 5 kW class SOFC system was operated with a hydrogen and a city gas. With a hydrogen, the total power of the stacks was about 7.1 kWDC and electrical efficiency was about 49.3% at 80 A. With a city gas, the total power of the stacks was about 5.7 $kW_{DC}$ and electrical efficiency was about 38.8% at 60 A. Under self-sustained operating condition, the system efficiency including a power conditioning loss and a consumed power by BOPs was about 30.2%.

• Korean Journal of Agricultural Science
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• v.39 no.4
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• pp.467-471
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• 2012

In this study, we investigated the antioxidative and antiaging activity of Perilla frutescens using LLC-$PK_1$ porcine renal epithelial cell and WI-38 human diploid fibroblast cell. The extract from Perilla frutescens showed strong protective effect against nitric oxide (NO) and superoxide ($O_2{^-}$)-induced oxidative stress generated by sodium nitroprusside (SNP) and pyrogallol, respectively. The result showed that P. frutescens increased the cell viability and showed scavenging activity of NO and $O_2{^-}$. In addition, the extract of P. frutescens exerted the protective effect against peroxynitrite ($ONOO^-$) induced by 3-morpholinosydnonimine. It suggests that P. frutescens would have the protective role against $ONOO^-$ itself and its precursors, NO and $O_2{^-}$. Furthermore, the aging model of hydrogen peroxide ($H_2O_2$)-treated WI-38 human diploid fibroblast was employed to investigate the anti-aging effect of P. frutescens. $H_2O_2$-treated WI-38 cells showed the loss of cell viability, however before-treatment with P. frutescens to WI-38 cells under premature senescence could delay the cellular aging process. The present study suggests the antioxidative and antiaging potential against free radical-induced oxidative damage of P. frutescens.

• Archives of Pharmacal Research
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• v.28 no.8
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• pp.942-947
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• 2005

Peroxynitrite is a potent neurotoxic molecule produced from a reaction between NO and super-oxide and induces NO-mediated inflammation under neuropathological conditions. Previously, we reported that glucose deprivation induced ATP depletion and cell death in immunostimulated astrocytes, which was mainly due to peroxynitrite. In this study, the role of MAPKs (ERK1/2, p38MAPK, and JNK/SAPK) signal pathway in the SIN-1/glucose deprivation-induced death of astrocytes was examined. A combined treatment with glucose deprivation and $50 {\mu}M$ SIN-1, an endogenous peroxynitrite generator, rapidly and markedly increased the death in rat primary astrocytes. Also, SIN-1/glucose deprivation resulted in the activation of MAPKs, which was significantly blocked by the treatment with $20{\mu}M$ MAPKs inhibitors (ERK1/2, PD98059; p38MAPK, SB203580; JNK/SAPK, SP600125). Interestingly, SIN-1/glucose deprivation caused the loss of intracellular ATP level, which was significantly reversed by MAPKs inhibitors. These results suggest that the activation of MAPKs plays an important role in SIN-1/glucose deprivation-induced cell death by regulating the intracellular ATP level.

• The Korea Journal of Herbology
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• v.23 no.3
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• pp.53-60
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• 2008

Objectives : Oxidative stress has a critical role in neurodegenerative diseases. In this study, we investigated the antioxidant and neuroprotective effects of the ethanolic extract of Banryong-hwan (BRHE) in SH-SY5Y cells and primary rat mesencephalic dopaminergic neurons. Methods : To assess the antioxidant effects, we carried out 1,1-diphenyl-2-picrylhydrazyl(DPPH) free radical scavenging assay, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)(ABTS) radical cation decolorization assay, and determination of total polyphenolic content. We evaluated the effect of BRHE treatment on neuroprotection against 6-hydroxydopamine(6-OHDA) toxicity using thiazolyl blue tetrazolium bromide(MTT) assay, nitric oxide(NO) assay, reactive oxygen species(ROS) assay in SH-SY5Y cells and tyrosine hydroxylase(TH) immunocytochemistry in primary rat mesencephalic dopaminergic neurons. Results : BRHE showed IC50 values of 328.10 ${\mu}g/mL$ and 43.12 ${\mu}g/mL$ in DPPH assay and in ABTS assay, respectively. Total polyphenolic content was 180.76 ${\mu}g/mL$. In SH-SY5Y cells, BRHE significantly attenuated the toxicity induced by 6-OHDA at the concentrations of 25-100 ${\mu}g/mL$ pre- and post- treatment in MTT assay. While 6-OHDA increased the NO and ROS contents, BRHE decreased them in a dose dependent manner. Moreover, in primary dopaminergic neuron culture, BRHE significantly protect-ed the dopaminergic cell loss against 6-OHDA toxicity up to 136% at the concentration of 75 ${\mu}g/mL$. Conclusions : These results demonstrate that BRHE has neuroprotective effect against 6-OHDA induced neurotoxicity through decreasing NO and ROS generation.

• Corrosion Science and Technology
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• v.6 no.5
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• pp.233-238
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• 2007

Due to the occasional occurrence of a localizedcorrosion such as a SCC and pitting in steam generator tubing(Alloy 600), leading to a significant economical loss, an effective repair technology is needed. For a successful electrodeposition inside a tube, many processes should be developed. Among these processes, an anode to be installed inside a tube, a degreasing condition to remove any dirt and grease, an activation condition for a surface oxide elimination, a strike layer forming condition which needs to be adhered tightly between an electroforming layer and a parent tube and a condition for an electroforming layer should be established. Through a combination of these various process condition parameters, the desired material properties can be acquired. Among these process parameters, various material properties including a mechanical property and its variation along with the height of the electrodeposit inside a tube as well as its thermal stability and SCC resistance should be assessed for an application in a plant. This work deals with the material properties of the Ni electrodeposits formed inside a tube by using the anode developed in this study such as the current efficiency, hardness, tensile property, thermal stability and SCC behavior of the electrodeposit in a 40wt% NaOH solution at $315^{\circ}C$. It was found that a variation of the material properties within the entire length of the electrodeposit was quite acceptable and the Ni electrodeposit showed an excellent SCC resistance.

• Corrosion Science and Technology
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• v.19 no.3
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• pp.122-130
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• 2020

In this study, a corrosion failure analysis of a heat transport pipe was conducted, as the result of a pinhole leak. Interestingly, the corrosion damage occurred externally in the pipeline, resulting in severe thickness reduction near the seam line. Also, while a stable magnetite protective film formed on the inner surface, the manganese oxide formation occurred only on the outer surface. The interior and exterior of the pipe were composed of ferrite and pearlite. The large manganese sulfide and alumina inclusions were found near the seam line. In addition, the manganese sulfide inclusions resulted in grooving corrosion, which progressed in the seam line leading to the reduction in the thickness, followed by the exposure of the alumina in the matrix to the outer surface. To note, the corrosion was accelerated by pits generated from the boundaries separating the inclusions from the matrix, which resulted in pinhole leaks and water loss.

• Environmental Engineering Research
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• v.18 no.1
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• pp.29-35
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• 2013

This study noted that the actual mechanism of N-nitrosodimethylamine (NDMA) photodecomposition in the presence of $H_2O_2$ is missing from the previous works. This study investigated a key unknown reactive species (URS) enhanced by the addition of $H_2O_2$ during the photolysis of NDMA with $H_2O_2$, not hydroxyl radicals. In order to provide experimental evidences in support of URS formation, we have mainly used p-nitrosodimethylaniline, methanol, and benzoic acid as well-known probes of ${\cdot}OH$ in this study. Both loss of PNDA and formation of hydroxybenzoic acids were dependent on NDMA concentrations during the photolysis in a constant concentration of $H_2O_2$. In particular, competition kinetics showed that the relative reactivity of an URS was at least identical with ${\cdot}OH$-like reactivity. In addition, the decay of NDMA was estimated to be about 65% by the direct UV light and about 35% by the reactive species or URS generated through the photolysis of NDMA and $H_2O_2$. Therefore, our data suggest that a highly oxidizing URS is formed in the photolysis of NDMA with $H_2O_2$, which could be peroxynitrite ($ONOO^-$) as a potent oxidant by itself as well as a source of ${\cdot}OH$.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1283-1284
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• 2007

The barium strontium calcium titanate((Ba,Sr,Ca)$TiO_3$) powders prepared by the sol-gel method and $MnCO_3$ as acceptor were mixed oxide method. The microstructure was investigated with variation of $Pr_{2}O_{3}$ amount. The BSCT powder and $Pr_{2}O_{3}$ were mixed with organic vehicle(Ferro. B75001). BSCT thick films were fabricated by the screen-printing method on alumina substrates. The bottom electrode was Pt and upper electrode was Ag, respectively. All BSCT thick films were sintered at $1420^{\circ}C$, for 2h. The result of the differential thermal analysis(DTA), exothermic peak at around $654^{\circ}C$ due to the formation of the polycrystalline perovskite phase. In the X-ray diffraction(XRD) patterns, all BSCT thick films showed the typical perovskite polycrystalline structure and no pyrochlore phase was dbserved. The microstructure investigated by scanning electron microscope(SEM). Pore and grain size of BSCT thick films were decreased with increasing amount of $Pr_{2}O_{3}$ dopant. And the average grain size and thickness of BSCT thick films doped with 0.1 mol% $Pr_{2}O_{3}$ was $3.09{\mu}m$, $60{\mu}m$, respectively. The relative dielectric constant decreased and dielectric loss decreased with increasing amount of $Pr_{2}O_{3}$ dopant, the values of the BSCT thick films no doped with $Pr_{2}O_{3}$ were 7443 and 4 % at 1 kHz, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.381-381
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• 2010

$(ZrO_2)_{0.66}(HfO_2)_{0.34}$ thin films as gate dielectrics have been proposed to overcome the problems of tunneling current and degradation mobility inachieving a thin equivalent oxide thickness. An extremely thin $SiO_2$ layer is used in order to separate the carrier in MOSFET channel from the dielectric field fluctuation caused by phonons in the dielectric which decreases the carrier mobility. The electronic and optical properties influenced the device performance to a great extent. $(ZrO_2)_{0.66}(HfO_2)_{0.34}$ dielectric films on p-Si (100) were grown by atomic layer deposition method, for which the conduction band offsets, valence band offsets and band gapswere obtained by using X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. The band gap, valence and conduction band offset values for $(ZrO_2)_{0.66}(HfO_2)_{0.34}$ dielectric thin film, grown on Si substrate were about 5.34, 2.35 and 1.87 eV respectively. This band alignment was similar to that of $ZrO_2$. In addition, The dielectric function (k, $\omega$), index of refraction n and the extinction coefficient k for the $(ZrO_2)_{0.66}(HfO_2)_{0.34}$ thin films were obtained from a quantitative analysis of REELS data by comparison to detailed dielectric response model calculations using the QUEELS-$\varepsilon$(k, $\omega$)-REELS software package. These optical properties are similar with $ZrO_2$ dielectric thin films.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.31 no.1
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• pp.12-21
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• 2018

Objectives : Inflammation is one of the self-protective abilities against tissue injury, and it has clinical symptoms like redness, heat, swelling, pain, and loss of function. The purpose of this study is to examine inhibitory effects of Naetakchunkeum-san (NTCKS) on nitric oxide (NO), Prostaglandin E2 (PGE2), inducible NOS (iNOS), cyclooxygenase-2 (COX-2), and phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), which play a major role in inflammatory response. Methods : The experiment was performed using Raw 264.7 cells pretreated with NTCKS extracts. Cell viability was determined by MTT assay. To evaluate anti-inflammatory effects of NTCKS, we examined NO and $PGE_2$ production in LPS-induced macrophages. We also investigated effects of NTCKS on iNOS, Cox-2, and ERK1/2 expression using western blot. Results : In MTT assay, no cytotoxicity of NTCKS (50, 100, 150, $200{\mu}g/ml$) on RAW 264.7 cell was found. LPS-induced NO production was decreased after treatment with NTCKS (150, $200{\mu}g/ml$)(p<0.05). $PGE_2$ was decreased after treatment with NTCKS (150, $200{\mu}g/ml$)(p<0.05). NTCKS inhibited LPS-induced expressions of iNOS and COX-2 in a dose-dependent manner. Increased phosphorylation of ERK1/2 by LPS was decreased by NTCKS in a dose-dependent manner. Conclusions : According to above experiments, NTCKS may be applied to inflammatory diseases such as atopic dermatitis, rheumatoid arthritis, and inflammatory bowel disease.