• 한국전기전자재료학회논문지
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• 제19권5호
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• pp.461-466
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• 2006

To investigate the ZnO thin films which are interested in the next generation of short wavelength LEDs and Lasers, the ZnO thin films were deposited by RF sputtering system. At sputtering process of ZnO thin films, substrate temperature, work pressure respectively is $100^{\circ}C$ and 15 mTorr, and the purity of target is ZnO 5 N. The ZnO thin films were in-situ annealed at $600^{\circ}C$ in $O_2$ atmosphere. The thickness of ZnO thin films has implemented about $1.6{\mu}m$ at SEM analysis after in-situ annealing process. We have investigated the crystal structure of substrates, and so structural properties of ZnO thin films has estimate by using XRD, FWHM, FE-SEM and AFM. XRD and FE-SEM showed that ZnO thin films grown on substrates had a c-axis preferential orientation in the [0001] crystal direction. XPS spectra showed that ZnO thin film was showed a peak positions corresponding to the O1s and the Zn2p. As form above XPS, we showed that the atom ratio of Zn:O related 1:1.1504 on ZnO thin film, so we could obtained useful information for p-type ZnO thin film.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.156-168
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• 2023

This study investigates the high temperature oxidation behaviour of a Ni-20Cr-1.2Si (wt.%) alloy in steam from 1200 ℃ to 1350 ℃ by Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD). The results demonstrate that exposed Ni-based alloy developed a thin oxide scale, consisted mainly of Cr₂O₃. The oxidation kinetics obtained from the experimental results was applied to evaluate the hydrogen generation considering a simplified reactor core model with different cladding alloys following an unmitigated Loss-Of-Coolant Accident (LOCA) scenario in a hypothetical Small Modular Reactor (SMR). Overall, experimental data and simulations results show that both Fe-based and Ni-based alloys may enhance cladding survivability, delaying its melting, as well as reducing hydrogen generation under accident conditions compared to Zr-based alloys. However, a substantial neutron absorption occurs when Ni-based alloys are used as cladding for current uranium-dioxide fuel systems, even when compared to Fe-based alloys.

• BMB Reports
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• 제32권6호
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• pp.585-593
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• 1999

The water and methanol extracts of Artemisia argyi showed significant cytotoxicities against J774A.1 cells but not so much against normal leukocytes. The cytotoxicities were found to be dependent on the extract concentration and the incubation time. The concentration of water and methanol extracts inhibiting 50% of cell proliferation ($IC_{50}$) were estimated to be 44.2 mg/ml and 71.6 mg/ml, respectively. In the presence of Artemisia argyi water extract, total superoxide dismutase (CuZnSOD and MnSOD) activities of media, cytoplasmic and mitochondrial fractions of J774A.1 cells increased in accordance with cytotoxicity. MnSOD was found to be the main component of enhanced total SOD activities, particulary in the mitochondrial fraction. In contrast to SOD, catalase and glutathione peroxidase (GPx) were not found in any instance of the current investigation. In addition, substantial amount of $O_2^-$ appeared to be generated in the mitochondrial fraction under the influence of Artemisia argyi. All data put together, it is postulated that Artemisia argyi extracts seem to stimulate $O_2^-$ generation in mitochondria of J774A.1 cells with concomitant increases of SODs. Since $H_2O_2$, the reaction product of SOD on $O_2^-$, is known to be readily converted to very toxic $OH{\cdot}$ in the absence of catalase and/or GPx cooperation, toxicity derived from ROS such as $O_2^-$, $H_2O_2$, and $OH{\cdot}$ may be the main cause of necrosis and/or apoptosis of J774A.1 cells.

• 대한한방내과학회지
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• 제27권1호
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• pp.178-187
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• 2006

Objectives : Peroxynitrite $(ONOO^-),\;{\cdot}O_2^-$ and nitric oxide (NO) are cytotoxic species that can oxidize several cellular components such as proteins, lipids and DNA. It has been implicated in the aging process and age-related disease such as Alzheimer's disease, rheumatoid arthritis, cancer and atherosclerosis. The aim of this study was to investigate $ONOO^-$ scavengactivities, and that of its precursors, NO and ${\cdot}O_2^-$ of Samjunghwan. Methods : To investigate $ONOO^-,\;NO,\;{\cdot}O_2^-$ scavenging activities, fluorescent probes, namely 2',7'-dichlorodihydrofluorescein diacetate (DCFDA), 4,5-diaminofluorescein (DAF-2) and dihydrorhodamine 123 (DHR 123) were used. Results : Samjunghwan markedly scavenged authentic $ONOO^-,\;{\cdot}O_2^-$ and NO. It also inhibited $ONOO^-$ induced by .02' and NO which are derived from SIN-I. Furthermore, Samjunghwan inhibited $ONOO^-$, ${\cdot}O_2^-$ and NO generation in LPS-treated ICR mouse kidney postmitochondria. Conclusions : These results suggest that Samjunghwan is an effective $ONOO^-,\;{\cdot}O_2^-$ and NO scavenger, and that this substance has a potential role as an inhibitor of aging process, and in therapy against age-related diseases.

• 약학회지
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• 제44권4호
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• pp.354-357
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• 2000

Two ellagitannins, pedunculagin and 2,3-(S)-Hexahydroxydiphenoyl (HHDP)-D -glucose and three condensed tannins, (+)-catechin, (-)-epicatechin and procyanidin B-4 which were isolated from Rubus coreanum were evaluated for their antioxidative effects with 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and lipid peroxidation generation system mediated by addition of $H_2O$$_2$to rat liver homogenate (TBARS). The ellagitannins, 2,3-(S)-HHDP-D-glucose and pedunculagin, showed more potent antioxidative activities by DPPH and TBARS than condensed tannins.

• 한국전기전자재료학회논문지
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• 제19권8호
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• pp.769-774
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• 2006

In this paper the ZnO thin films, which has used spotlight of next generation short wavelength LEDs and semiconductor laser were deposited based on RF magnetron sputtering is described. The temperature at substrate and work pressure, which has implemented in sputtering process of ZnO thin films were settle down at $100^{\circ}C$ and 15 mTorr respectively. The ZnO 5N has used target. The thickness of ZnO thin films was about $1.6{\mu}m$ which was measured by SEM analysis after the sputtering process. Structural properties of ZnO thin films by in-situ and atmosphere annealing were analyzed by XRD. Transformation of grain size and surface roughness were observed by AFM. XPS spectra showed that ZnO thin film had a peak positions corresponding to the $Zn_{2p}$ and the $O_{1s}$. As form above XPS, we confirmed that post-annealing condition changed the atom ratio of Zn/O and microstructure in ZnO thin films.

• 대한한방내과학회지
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• 제29권4호
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• pp.835-845
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• 2008

Objectives : The purpose of this study was to investigate the effect of FS for the modulation of ROS and MMP in a hypoxic model of cultured rat cortical cells. Methods : For the effect of FS on the viability, FS was added to culture media (neurobasal supplemented with B27) and cell viability was measured by LDH assay. To investigate the effects of FS on ROS generation and MMP preservation, cells grown in FS-containing media were given a hypoxic shock(2% $O_2/5%$ $CO_2$, $37^{\circ}C$, 3 hrs) on DIV 10, stained with $H_2DCF-DA$(10 nM) and JC-1, respectively, and observed by fluorescent microscope. Results : 1. FS has a protective effect of cortical cells in both normoxia and hypoxia. 2. FS reduced the generation of ROS and this reduction was especially significant at 3 days after hypoxia. 3. FS was effective for the maintenance of MMP in hypoxia, and this efficacy was especially significant at 3 days after hypoxia. Conclusions : Taken together, these results indicate that FS attenuates ROS generation and MMP dissipation, which eventually protects from neuronal cell death in hypoxia.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.1063-1066
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• 2005

In this paper, we developed the UHF RFID system for EPC Class1 Generation 2 specification. The RFID is a technique of identifying an object using radio frequency transmission. UHF band RFID system communication between Reader and Tag for provide the power to tag when be active when reader’s command finished the transfer. RFID technology can be applied to the supply chain, security, logistics industry and etc. Especially, UHF RFID is worth noticing because of its relatively long identification rage and commercial UHF RFID systems are under development.

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2743-2750
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• 2011

Lanthanide(III)-cored complex as a wavelength conversion material has been successfully designed and synthesized for highly efficient dye-sensitized solar cells, for the first time, since light with a short wavelength has not been effectively used for generating electric power owing to the limited absorption of these DSSCs in the UV region. A black dye (BD) was chosen and used as a sensitizer, because BD has a relatively weak light absorption at shorter wavelengths. The overall conversion efficiency of the BD/WCM device was remarkably increased, even with the relatively small amount of WCM added to the device. The enhancement in $V_{oc}$ by WCM, like DCA, could be correlated with the suppression of electron recombination between the injected electrons and $I_3{^-}$ ions. Furthermore, the short-circuit current density was significantly increased by WCM with a strong UV light-harvesting effect. The energy transfer from the Eu(III)-cored complex to the $TiO_2$ film occurred via the dye, so the number of electrons injected into the $TiO_2$ surface increased, i.e., the short-circuit current density was increased. As a result, BD/WCM-sensitized solar cells exhibit superior device performance with the enhanced conversion efficiency by a factor of 1.22 under AM 1.5 sunlight: The photovoltaic performance of the BD/WCM-based DSSC exhibited remarkably high values, $J_{sc}$ of 17.72 mA/$cm^2$, $V_{oc}$ of 720 mV, and a conversion efficiency of 9.28% at 100 mW $cm^{-2}$, compared to a standard DSSC with $J_{sc}$ of 15.53 mA/$cm^2$, $V_{oc}$ of 689 mV, and a conversion efficiency of 7.58% at 100 mW $cm^{-2}$. Therefore, the Eu(III)-cored complex is a promising candidate as a new wavelength conversion coadsorbent for highly efficient dye-sensitized solar cells to improve UV light harvesting through energy transfer processes. The abstract should be a single paragraph which summaries the content of the article.

• 한국수정란이식학회지
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• 제31권3호
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• pp.299-305
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• 2016

Although cryopreservation of sperm is routinely used for clinical requirement, it has some problems, such as high generation of reactive oxygen species (ROS) and cold-shock. To reduce the detrimental damage in sperm, anti-oxidants were added to cryoprotectant for sperm. Curcumin is one of anti-oxidants, which are added in cryoprotectants. However, recent studies have demonstrated that curcumin decreases sperm viability and motility. This study was performed to identify the effect of curcumin on hydrogen peroxide ($H_2O_2$)-exposed bovine sperm, which were cryopreserved-thawed. In $H_2O_2$-exposed bovine sperm, reactive oxygen species (ROS) were significantly reduced by treatment with curcumin in a dose-dependent manner (p < 0.05). Among tested concentrations of curcumin (1 to $50{\mu}M$), 30 and $50{\mu}M$ curcumin showed anti-oxidant effect on $H_2O_2$-induced ROS generation. On the other hand, combination of 30 or $50{\mu}M$ curcumin with anti-oxidant $H_2O_2$ increased the percentage of apoptotic sperm compared to only $H_2O_2$ treatment. Sperm viability was also decreased in the combination of 30 or $50{\mu}M$ curcumin with $H_2O_2$ as judged by FDA/PI staining. $H_2O_2$-induced decrease in sperm progressive motility was recovered by treatment with $1{\mu}M$ curcumin. These results show that high concentration of curcumin has anti-oxidant effect, but it has also cytotoxic effect on bovine sperm. Sperm viability and motility might be more affected by cytotoxic signals of curcumin compared to antioxidant signals.