• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.59-62
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• 2006

Formability is requested to successfully develop of a metal bipolar plate for mass production. From this point of view, wider channel and land width is more helpful to improve formability. But the performance of the fuel cell can be affected by its channel and land shape. So it is very important to select proper channel and land shape not to deteriorate the fuel cell performance. In this work, 3-dimensional, non-isothermal numerical simulation was performed to analyse the effects of channel and land width on the fuel cell performance. 3 types of straight channel were selected for the numerical simulation. The simulation results reveal that wide channel and land width lower fuel cell performance and decrease voltage at a high current density region. Water activity, temperature, oxygen concentration distributions were investigated to find the reasons of performance degradation. The results show that wide channel and land width give an bad effect on fuel cell performance because of low cool ins efficiency and lack of oxygen gas under the land.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.3
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• pp.279-286
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• 1995

As Al-Li based alloys are to find widespread use in aerospace and other structural applications in which their low-density high specific stiffness properties be exploited, their mechanical properties must adequately match those of the which they intended to replace. In order to develop these purposed, the precipitation behaviors of the rapidly solidified Al-Li-Ti alloys aged at various temperature were investigated. ${\delta}'$ phase precipitated homogeneously in the matrix during not only melt quenching but also aging at the aging temperature of $160^{\circ}C\;and\;210^{\circ}C$. The addition of the Ti in Al-Li alloy promoted the formation of $\delta$' phase. The addition of Ti on the ${\delta}'$ solvus line had a little effect over the thermodynamics ${\delta}'$ solvus line. The reason for these behavior was that the ${\delta}'$ phase was suppressed to precipitate as much as supercooling by melt quenching. The discontinuous precipitation reaction occurred by the preferential growth of ${\delta}'$ phase due to the migration of grain boundary provided the driving force dependent of solute concentration fluctuations.

• Journal of Surface Science and Engineering
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• v.47 no.6
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• pp.311-315
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• 2014

Indium tin oxide (ITO) thin films (30 nm) were deposited on PET substrate by reactive DC magnetron sputtering using In/Sn(2, 5 wt.%) metal alloy target without intentionally substrate heating during the deposition under different DC powers of 70 ~ 110 W. The electrical properties were estimated by Hall-effect measurements system. The resistivity of ITO thin film deposited using In/Sn (5 wt.%) metal alloy target at low DC power increased with increasing annealing time. However, they increased with increasing annealing time at high DC power. In the case of ITO (Sn 2 wt%), we can't find clear change in resistivity with increasing annealing time. However, carrier density and mobility showed difference behavior due to change of oxygen vacancy.

• Journal of Electrochemical Science and Technology
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• v.10 no.1
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• pp.61-68
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• 2019

Well aligned $SnO_2$-doped ZnO nanorods were prepared by single step or 2-step electrochemical depositions in a mixture solution of zinc nitrate hexahydrate, ammonium hydroxide solution and 0.1 M tin chloride pentahydrate. The morphologies of electrochemically deposited $SnO_2$-doped ZnO were transformed from plain (or network) structures at low reduction potential to needles on hills at high reduction potential. Well aligned ZnO was prepared at intermediate potential ranges. Reduction reagent and a high concentration of Zn precursor were required to fabricate $SnO_2$ doped ZnO nanorods. When compared to results obtained by single step electrochemical deposition, 2-step electrochemical deposition produced a much higher density of nanorods, which was ascribed to less potential being required for nucleation of nanorods by the second-step electrochemical deposition because the surface was activated in the first-step. Mechanisms of $SnO_2$ doped ZnO nanorods prepared at single step or 2-step was described in terms of applied potential ranges and mass-/charge- limited transfer.

• The Korean Journal of Physiology and Pharmacology
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• v.23 no.3
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• pp.181-189
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• 2019

Curcumin, an active ingredient of Curcuma longa L., can reduce the concentration of low-density lipoproteins in plasma, in different ways. We had first reported that curcumin exhibits hypocholesterolemic properties by improving the apolipoprotein B (apoB) mRNA editing in primary rat hepatocytes. However, the role of curcumin in the regulation of apoB mRNA editing is not clear. Thus, we investigated the effect of curcumin on the expression of multiple editing components of apoB mRNA cytidine deamination to uridine (C-to-U) editosome. Our results demonstrated that treatment with $50{\mu}M$ curcumin markedly increased the amount of edited apoB mRNA in primary mouse hepatocytes from 5.13%-8.05% to 27.63%-35.61%, and significantly elevated the levels of the core components apoB editing catalytic polypeptide-1 (APOBEC-1), apobec-1 complementation factor (ACF), and RNA-binding-motif-protein-47 (RBM47), as well as suppressed the level of the inhibitory component glycine-arginine-tyrosine-rich RNA binding protein. Moreover, the increased apoB RNA editing by $50{\mu}M$ curcumin was significantly reduced by siRNA-mediated APOBEC-1, ACF, and RBM47 knockdown. These findings suggest that curcumin modulates apoB mRNA editing by coordinating the multiple editing components of the edito-some in primary hepatocytes. Our data provided evidence for curcumin to be used therapeutically to prevent atherosclerosis.

• Corrosion Science and Technology
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• v.19 no.6
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• pp.288-295
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• 2020

This study investigated the erosion-corrosion characteristics of 5038-H321 aluminum alloy in a natural seawater solution through various electrochemical experiments and flow rate parameters. Cathodic polarization experiments were conducted at flow rates ranging from 4 to 12 knots. Considering the concentration polarization section representing a relatively low current density, the range of the potentiostatic experiment was determined to be -1.6 to -1.0 V. The potentiostatic experiment was conducted at various potentials for 180 minutes in seawater. After the experiment, the corrosion characteristics were evaluated by observing surface morphology and measuring surface roughness. As a result, as the applied potential was lower, the amount of calcareous deposits increased and the roughness tended to increase. On the other hand, it was confirmed that the roughness was larger in the static condition than the flow rate condition due to the influence of the flow velocity. Variations in the chemical composition with flow rate variations were analyzed by energy-dispersive spectroscopy (EDS). In conclusion, the cathodic potential of AA5083-H321 in seawater was determined to be -1.0 V.

• Journal of Surface Science and Engineering
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• v.54 no.1
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• pp.12-17
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• 2021

Among the various precious metals, silver is used in various fields because of its low price than other precious metals. However, the surface of silver remains after rain in the atmosphere containing sulfur ions and chlorine ions, causing silver corrosion and discoloration. Existing documents have developed a anode to prevent corrosion but that are concentrated on secondary batteries. This study tried to prevent corrosion and discoloration of silver by using an Al sacrificial anode. Sulfuric acid decreased the potential of silver and increased the current density at active polarization and OCP. The amount of corrosion of silver with the Al sacrificial anode was reduced from 0.5 % to 6.5%. When silver is used for decoration outside, corrosion and discoloration of silver can be suppressed by installing an Al anode.

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.39-44
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• 2022

The light extraction technology for improving the light efficiency of OLEDs is the core technology for extracting the light inside the OLEDs to the outside. This study demonstrates a simple method to generate random nanostructures (RNSs) containing high refractive index nanoparticles to improve light extraction and viewing angle characteristics. A simple dry low-temperature process makes the nanostructured scattering layer on the polymer resin widely used in the industry. The scattering layer has the shape of randomly distributed nanorods. To control optical properties, we focused on changing the shape and density of RNSs and adjusting the concentration of high refractive index nanoparticles. As a result, the film of the present invention exhibits a perpendicular transmittance of 85% at a wavelength of 550 nm. This film was used as a scattering layer to reduce substrate mode loss and improve EL efficiency in OLEDs.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.11 no.4
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• pp.19-33
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• 1982

Briquette ashes, one of important solid wastes in Korea, have relatively high compression strength in spite of their low density, and provide sufficient surface area and some adsorption capacity. Results of this research show that a fixed-film biological process using briquette ashes as media can accomplish BOD removal efficiencies in treating organic wastewaters such as alcoholic waste, diluted nightsoil and sewage , and formula can be derived to determine the effluent BOD concentrations by superficial or volumetric organic loadings. Settling tanks may be required because effluent SS concentration is deteriorated due to the SS in influent or due to the slough-off of slime layer on the media when briquette ashes are utilized for a long period.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.73-74
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• 2022

The corrosion inhibitive effect of a new hydrazone-based heterocyclic compound for steel in simulated concrete pore solution with 3.5 wt.% sodium chloride was investigated by experimental and computational techniques. Electrochemical studies, up to 30 days of immersion, and surface analysis (X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscope (SEM)) were performed to assess the corrosion protection abilities of investigated compound for steel rebar. Results showed that adding the organic compound to the chloride contaminated concrete pore solution decreased the corrosion rate of the steel rebar thanks to the effective adsorption of inhibitor molecules. After 30 days of immersion of steel rebar in inhibited chloride contaminated synthetic concrete pore solution, the inhibition efficiency exceeded 80% at low concentration of 1 mmol/L. Computational studies by Density Functional based Tight Binding (DFTB) method revealed the formation of covalent bonds between the hydrazone molecule and the iron surface.