• Korean Journal of Environmental Agriculture
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• v.13 no.1
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• pp.83-89
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• 1994

The number of colonies often decreased more than would be expected in a dilution from 1:50 to 1:100; however, a lack of agreement between the dilution series and the number of colonies obtained also occurred at higher dilutions. In the experiments with each soil subsample, there was sometimes poor agreement between the number of colonies obtained at the same dilution from the A and B subsamples. However, repeated 1:50 dilutions of soil suspensions of subsamples A and B yielded similar numbers of colonies. In the second experiment series conducted with a second composite soil sample, the number of colonies obtained from each soil subsample decreased following air drying. The results suggest that it was difficult to obtain a uniform distribution of Pythium propagules in the two sugarcane field soils tested. The high number of propagules detected at the 1:50 dilution could have been due to hyphal fragments or connected hyphal swellings that separated during the final mixing or during plating.

• Journal of the Korean institute of surface engineering
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• v.45 no.6
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• pp.248-256
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• 2012

A Pd-based hydrogen membranes for hydrogen purification and separation need high hydrogen perm-selectivity. The surface roughness of the support is important to coat the pinholes free and thin-film membrane over it. Also, The pinholes drastically decreased the hydrogen perm-selectivity of the Pd-based composite membrane. In order to remove the pinholes, we introduced various surface pre-treatment such as alumina powder packing, nickel electro-plating and micro-polishing pre-treatment. Especially, the micro-polishing pretreatment was very effective in roughness leveling off the surface of the porous nickel support, and it almost completely plugged the pores. Fine Ni particles filled surface pinholes with could form open structure at the interface of Pd alloy coating and Ni support by their diffusion to the membrane and resintering. In this study, a $4{\mu}m$ surface pore-free Pd-Cu-Ni ternary alloy membrane on a porous nickel substrate was successfully prepared by micro-polishing, high temperature sputtering and Cu-reflow process. And $H_2$ permeation and $N_2$ leak tests showed that the Pd-Cu-Ni ternary alloy hydrogen membrane achieved both high permeability of $13.2ml{\cdot}cm^{-2}{\cdot}min^{-1}{\cdot}atm^{-1}$ permation flux and infinite selectivity.

• Journal of the Korean institute of surface engineering
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• v.38 no.3
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• pp.100-105
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• 2005

Cr-Si-C-N coatings were deposited on steel substrate (SKD 11) by a hybrid system of arc ion plating (AIP) and sputtering techniques. From XRD, XPS, and HRTEM analyses, it was found that Cr-Si-C-N had a fine composite microstructure comprising nano-sized crystallites of Cr(C, N) well distributed in the amorphous phase of $Si_3N_4/SiC$ mixture. Microhardness of Cr(C, N) coatings and Cr-Si-N coatings were reported about $\~22 GPa$ and $\~35 GPa$, respectively. As the Si was incorporated into Cr(C, N) coatings, The Cr-Si-C-N coatings having a Si content of $9.2 at.\%$ showed the maximum hardness value. As increased beyond Si content of $9.2 at.\%$, the interaction between nanocrystallites and amorphous phase was gone, the hardness was reduced as dependent on amorphous phase of $Si_3N_4/SiC$. In addition, the average coefficient of Cr-Si-C-N coatings largely decreased compared with Cr(C, N) coatings.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.282-287
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• 2005

Palladium membranes, which are permselective to hydrogen separation, were used for the hydrogen purification and in membrane reactors for improving conversions by shifting the reaction equilibrium. Palladium/ceramic composite membranes were prepared by electroless plating technique and then etched in titanium chloride ($TiCl_4$) as a post treatment to enhance the membrane's durability. These membranes were used for membrane reactors in water gas shift (WGS) reaction. CO conversions for the membrane reactor were obtained according to experimental parameters and compared to the traditional reactor without a palladium/ceramic membrane. As a result, CO conversion using palladium membrane reactor at an appropriate condition was over 20~25% greater than that without the membrane reactor. The stability in the long-term test of up to 120 h for WGS reaction with the membrane reactor was good without the degredation of CO conversion.

• Korean Journal of Metals and Materials
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• v.48 no.10
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• pp.884-892
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• 2010

To modify the physical properties of Cu thin films, gelatin is generally used as an additive. In this study, we assessed the effect of gelatin on the mechanical properties of electrodeposited Cu films. For this purpose, Cu/gelatin composite films were fabricated by adding 100 ppm of gelatin to an electrolyte, and tension and indentation tests were then performed. Additional tests based on pure Cu films were also performed for comparison. The Cu films containing gelatin presented a smaller grain size compared to that of pure Cu films. This increased the hardness of the Cu films, but addition of gelatin did not significantly affect the elastic modulus of the films. Cu films prepared at room temperature showed no significant change in the yield strength and tensile strength with an addition of gelatin, but we observed a dramatic decrease in the elongation. In contrast, Cu films prepared at $40^{\circ}C$ with gelatin presented a significant increase in the yield strength and tensile strength after the addition of gelatin. Elongation was not affected by adding gelatin. Presumably, the results would be closely related to the preferred orientation of the Cu thin film with the addition of gelatin and at temperatures that lead to a change in the microstructure of the Cu thin films.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.4
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• pp.13-16
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• 2013

A lot of various researches have been going on to use heat spreader for LED module. Nano porous aluminum anodic oxide (AAO) applied LED, which is produced from anodization, is easy and economically advantageous. Convensional LED module is consist of aluminum/adhesive/copper circuit. The polymer adhesive in this module is used as heat spreader. However the thermal emission of LED component is degraded because of low heat conductivity of polymer and also reliability of LED component is reduced. Therefore, AAO in this work was applied to heat spreader of LED module which has higher heat conductivity compare to polymer. Bonding strength between AAO and copper circuit was improved with Ti/Cu seed layer by copper sputtering process (DBC) before the bonding. And this copper circuit has been fabricated by electro plating method. Peel strength of AAO and copper circuit in this work showed range between 1.18~1.45 kgf/cm with anodizing process which is very suitable for high power LED application.