• Journal of Embryo Transfer
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• v.28 no.3
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• pp.193-198
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• 2013

This study was designed to evaluate the effect of L-cysteine on sperm characteristics and oocyte cleavage in vitro in Korean native cattle. For this study, the freezing of diluted semen were added with Triladyl containing 20% egg-yolk and/or 0, 5, 10 and 20 mM L-cysteine before cryopreservation. The viability in frozen-thawed sperm were estimated by SYBR14/PI double stain, acrosome damage with FITC-PNA, mitochondria intact with Rhodamin123 and hydrogen peroxide($H_2O_2$) level with carboxy-DCFDA by flow-cytometry. The developmental capacity was also assessed with cleavage rates in oocytes fertilized in vitro by frozen-thawed sperm. In results, the sperm viability was significantly increased in 10 mM and 20 mM concentrations of L-cysteine than other groups (p<0.05). In addition, acrosome damage was significantly decreased in 10 mM and 20 mM concentrations of L-cysteine than other groups (p<0.05). The mitochondria intact was also significantly increased in 10 mM and 20 mM concentrations of L-cysteine than other groups (p<0.05). On the other hand, the cleavage rates were significantly increased in 0 mM, 5 mM and 10 mM groups than 20 mM concentration of L-cysteine (p<0.05). The oocyte degeneration of oocytes were significantly decreased in 0 mM, 5 mM and 10 mM groups than in 20 mM L-cysteine group (P<0.05). However, there are no significantly differences among the L-cysteine treatment groups. We suggest that concentration of 10 mM L-cysteine have beneficial impact for sperm cryopreserved in Korean native cattle. This result also could be recommended for artificial insemination program if supported by an improvement in the fertility results and required further study.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.91-91
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• 2013

Imagine a world where we could biomanufacture hybrid nanomaterials having atomic-scale resolution over functionality and architecture. Toward this vision, a fundamental challenge in materials science is how to design and synthesize protein-like material that can be fully self-assembled and exhibit information-specific process. In an ongoing effort to extend the fundamental understanding of protein structure to non-natural systems, we have designed a class of short peptides to fold like proteins and assemble into defined nanostructures. In this talk, I will talk about new strategies to drive the self-assembled structures designing sequence of peptide. I will also discuss about the specific interaction between proteins and inorganics that can be used for the development of new hybrid solar energy devices. Splitting water into hydrogen and oxygen is one of the promising pathways for solar to energy convertsion and storage system. The oxygen evolution reaction (OER) has been regarded as a major bottleneck in the overall water splitting process due to the slow transfer rate of four electrons and the high activation energy barrier for O-O bond formation. In nature, there is a water oxidation complex (WOC) in photosystem II (PSII) comprised of the earthabundant elements Mn and Ca. The WOC in photosystem II, in the form of a cubical CaMn4O5 cluster, efficiently catalyzes water oxidation under neutral conditions with extremely low overpotential (~160 mV) and a high TOF number. The cluster is stabilized by a surrounding redox-active peptide ligand, and undergo successive changes in oxidation state by PCET (proton-coupled electron transfer) reaction with the peptide ligand. It is fundamental challenge to achieve a level of structural complexity and functionality that rivals that seen in the cubane Mn4CaO5 cluster and surrounding peptide in nature. In this presentation, I will present a new strategy to mimic the natural photosystem. The approach is based on the atomically defined assembly based on the short redox-active peptide sequences. Additionally, I will show a newly identified manganese based compound that is very close to manganese clusters in photosystem II.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.375-381
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• 2010

In this paper, the heat-transfer characteristics of steam reforming in an annular reactor are presented. Heat is supplied by the catalytic combustion of syn-gas. The thermal behaviors of exothermic and endothermic reactions in a directly coupled concentric-tube packed-bed reactor were investigated experimentally. The gas mixture supplied for catalytic combustion consisted of the off-gas emitted from MCFC anode. Methane in steam at a suitable S/C (steam-to-carbon) ratio was used in the reforming reactions. On the basis of the experimental results, a simple simulation was performed to predict the temperature profile required in the reforming side of the reactor to achieve optimum hydrogen yield. The results of this study may be utilized as reference data in future studies for further development of coupled reactors.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1625-1629
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• 2011

Kinetic studies of the reactions of O,O-diphenyl Z-S-aryl phosphorothioates with X-benzylamines have been carried out in dimethyl sulfoxide at 55.0 $^{\circ}C$. The Hammett (log $k_2$ vs ${\sigma}_X$) and Bronsted [log $k_2$ vs $pK_a(X)$] plots for substituent X variations in the nucleophiles are biphasic concave downwards with a maximum point at X = H, and the unusual positive ${\rho}_X$ and negative ${\beta}_X$ values are obtained for the strongly basic benzylamines. The sign of the cross-interaction constant (${\rho}_{XZ}$) is negative for both the strongly and weakly basic nucleophiles. Greater magnitude of ${\rho}_{XZ}$ value is observed with the weakly basic nucleophiles (${\rho}_{XZ}$ = -2.35) compared to with the strongly basic nucleophiles (${\rho}_{XZ}$ = -0.03). The deuterium kinetic isotope effects ($k_H/k_D$) involving deuterated benzylamines [$XC_6H_4CH_2ND_2$] are primary normal ($k_H/k_D$ > 1). The proposed mechanism is a concerted $S_N2$ involving a frontside nucleophilic attack with a hydrogen bonded, four-center-type transition state for both the strongly and weakly basic nucleophiles. The unusual positive ${\rho}_X$ and negative ${\beta}_X$ values with the strongly basic benzylamines are rationalized by through-space interaction between the ${\pi}$-clouds of the electron-rich phenyl ring of benzylamine and the phenyl ring of the leaving group thiophenoxide.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.326-333
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• 1996

Dehydrogenation of 4-vinylcyclohexene(4-VCH) to ethylbenzene is elucidated via catalytic transfer hydrogenation with the heterogeneous catalyst of Pd/C. Hydrogen-donor solvent is ethanol or water. Oxidizers of the catalytic dehydrogenation reaction are mono- or dinitro compounds, $H_2O_2$, NaClOn (n=1~4), or oxygen at $70{\sim}110^{\circ}C$. The ratio of 4-VCH/Nitro compounds is 1:0.02 to 1:0.5 and 4-VCH vs. $H_2O_2$ or NaClOn (n=1~4) is 1:0.1 to 1:3.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.121-128
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• 2009

During a hypothetical high-pressure accident in a nuclear power plant (NPP), molten corium can be ejected through a breach of a reactor pressure vessel (RPV) and dispersed by a following jet of a high-pressure steam in the RPV. The dispersed corium is fragmented into smaller droplets in a reactor cavity of the NPP by the steam jet and released into other compartments of the NPP by a overpressure in the cavity. The fragments of the corium transfer thermal energy to the ambient air in the containment or interact chemically with steam and generate hydrogen which may be burnt in the containment. The thermal loads from the ejected molten corium on the containment which is called direct containment heating (DCH) can threaten the integrity of the containment. DCH in a NPP containment is related to many physical phenomena such as multi-phase hydrodynamics, thermodynamics and chemical process. In the evaluation of the DCH load, the melt dispersion rates depending on the RPV pressure are the most important parameter. Mostly, DCH was evaluated by using lumped-analysis codes with some correlations obtained from experiments for the dispersion rates. In this study, MC3D code was used to evaluate the dispersion rates in the APR1400 NPP during the high-pressure accidents. MC3D is a two-phase analysis code based on Eulerian four-fields for melt jet, melt droplets, gas and water. The dispersion rates of the corium melt depending on the RPV pressure were obtained from the MC3D analyses and the values specific to the APR1400 cavity geometry were compared to a currently available correlation.

• Korean Journal of Materials Research
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• v.22 no.3
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• pp.130-135
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• 2012

We present a method of graphene synthesis with high thickness uniformity using the thermal chemical vapor deposition (TCVD) technique; we demonstrate its application to a grid supporting membrane using transmission electron microscope (TEM) observation, particularly for nanomaterials that have smaller dimensions than the pitch of commercial grid mesh. Graphene was synthesized on electron-beam-evaporated Ni catalytic thin films. Methane and hydrogen gases were used as carbon feedstock and dilution gas, respectively. The effects of synthesis temperature and flow rate of feedstock on graphene structures have been investigated. The most effective condition for large area growth synthesis and high thickness uniformity was found to be $1000^{\circ}C$ and 5 sccm of methane. Among the various applications of the synthesized graphenes, their use as a supporting membrane of a TEM grid has been demonstrated; such a grid is useful for high resolution TEM imaging of nanoscale materials because it preserves the same focal plane over the whole grid mesh. After the graphene synthesis, we were able successfully to transfer the graphenes from the Ni substrates to the TEM grid without a polymeric mediator, so that we were able to preserve the clean surface of the as-synthesized graphene. Then, a drop of carbon nanotube (CNT) suspension was deposited onto the graphene-covered TEM grid. Finally, we performed high resolution TEM observation and obtained clear image of the carbon nanotubes, which were deposited on the graphene supporting membrane.

• Journal of the Korean Society of Safety
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• v.28 no.5
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• pp.5-9
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• 2013

Recently, eco-friendly sources of energy by fuel cells that use hydrogen as an energy source has emerged as the next generation of energy to solve the problem of environmental issues and exhaustion of energy. A solid oxide fuel cell(SOFC) classified based on the type of ion transfer mediator electrolyte has actively being researched. However, the reliability according to the thermal cycle is low during the operation of the fuel cell, and deformation problem comes from the difference in thermal expansion coefficient between the electrode material, the components made of ceramic material is also brittle, which means disadvantages in terms of the strength. Therefore, in this study, considering the states of the manufacturing and operating of SOFC single cells, the stress analyses in the each of the interfacial layer between the anode, electrolyte and the cathode were performed to get the basic data for reliability assessment of SOFC. The obtained results show that von Mises stress according to the thickness direction on operating state occurred maximum stress value in the electrolyte layer. And also the stresses inside the active area on a distance of 1 ${\mu}m$ from the electrode interface were estimated. Futhermore the evaluation was done for the variation of the stress according to the stage of the operation divided into three stages of manufacturing, stack, and operating.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2127-2132
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• 2013

Graphene thin film was prepared on the copper foils by chemical deposition, and the characteristic of graphene depending on $H_2$ and CH4 gas flow rates was analyzed by the Raman spectra. The graphene formation was improved with increment of methan gas flow rates. The increment of hydrogen gas flow rate made high intensity of D($1350cm^{-1}$) and G($1580cm^{-1}$). The peak of D($1350cm^{-1}$) is related with the defects, and the 2D($2700cm^{-1}$) increased depending on the increment of amount of methan gas flow rate. The rate of G/2D indicates the quality of garphene to like a monolayer, and the small value of G/2D means better grapheme. The G/2D of graphene after annealed at $200^{\circ}C$ was 0.55 and improved the characteristic of graphene than the deposited-grapnene. Thin film transistor with graphene as an active channel was p-type semiconductor.

• Journal of computational fluids engineering
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• v.17 no.4
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• pp.16-23
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• 2012

Current display manufacturing processes apply thermal treatment of glass backplanes widely for hydrogen degassing, crystallization of thin-films, tempering, forming, and precompaction. Estimation of the characteristics of transient heating stages and thermal non-uniformities on a single glass substrate or in a stack of glasses are extremely helpful to understand non-homogeneity of mechanical and electronic features of nano/micro structures of end products. Based on simple heat transfer models and using an electric muffle furnace, temperature variations in a glass stack were predicted and measured for glass backplanes of $1.5{\times}1.85m^2$ in size and 0.7 mm in thickness. Except for the period of putting glass backplanes into the furnace, thermal radiation was the major heating mechanism for the treatment and theoretical predictions agreed well to the experimental temperatures on the backplanes. Using the theoretical model, thermal fields for a glass stack of glass-size, $2.2{\times}2.5m^2$, and of the number of sheets, 1 to 12, were calculated for practical design and manufacturing of the muffle furnace for large-scale displays, e.g. up to $8^{th}$ generation.