• Archives of design research
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• v.14 no.4
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• pp.157-165
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• 2001

The method to make ceramic pigments for 4 colour instead of ink in the process of the of set-printing and put them on the decal paper in the ceramic industry has been used to produce complicated images such as photographs or famous masterpieces. Offset-printing which is the production method for mass production, had enough worth to suffer the past high price of the production line. But today it is not suitable for the production method of small quantity and many kinds corresponding to needs for the various tastes and designs of consumers. Therefore I will put 4 colour printing method on the silkscreen, handiwork, suitable for the production method for small quantities and many variations to develop the methods that permit to cost effectively reproduce complex, high resolution, multicolor images. The study is expected to give value to ceramists who do various works and to be offered as the foundation in the field of design and expression.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.116-123
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• 2001

An automated injection molding design methodology has been developed to optimize multiple quality attributes, which are usually in conflict with each other, in injection molded parts. For the optimization, commercial CAE simulation tools and optimization techniques are integrated into the methodology. To decal with the multiple objective problem the relative closeness computed in TOPSIS(Technique for Order Preference by Similarity to Ideal Solution) is used as a performance measurement index for optimization multiple part defects. To attain robustness against process variation, Taguchi's quadratic loss function is introduced in the TOPSIS. Also, the modified complex method is used as an optimization tool to optimize objective function. The verification of the developed design methodology was carried out on simulation software with an actual model. Applied to production this methodology will be useful to companies in reducing their product development time and enhancing their product quality.

• Textile Coloration and Finishing
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• v.20 no.1
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• pp.8-15
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• 2008

We presented the modified decal-transfer lithography (DTL) and light stamping lithography (LSL) as new powerful methods to generate patterns of poly(dimethylsiloxane) (PDMS) on the substrate. The microstructures of PDMS fabricated by covalent binding between PDMS and substrate had played as barrier to locally control wettability. The transfer mechanism of PDMS is cohesive mechanical failure (CMF) in DTL method. In the LSL method, the features of patterned PDMS are physically torn and transferred onto a substrate via UV-induced surface reaction that results in bonding between PDMS and substrate. Additionally we have exploited to generate the patterning of rhodamine B and quantum dots (QDs), which was accomplished by hydrophobic interaction between dyes and PDMS micropatterns. The topological analysis of micropatterning of PDMS were performed by atomic force microscopy (AFM), and the patterning of rhodamine B and quantum dots was clearly shown by optical and fluorescence microscope. Furthermore, it could be applied to surface guided flow patterns in microfluidic device because of control of surface wettability. The advantages of these methods are simple process, rapid transfer of PDMS, modulation of surface wettability, and control of various pattern size and shape. It may be applied to the fabrication of chemical sensor, display units, and microfluidic devices.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.2
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• pp.76-84
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• 2002

On-line conversion estimation of enzymatic esterification reactions in solvent-free media was investigated. In principle, conversion to ester can be determined from the amount of water produced by the reaction, because water is formed as a by-product in a stoichiometric manner. In this study, we estimated the water production rate only from some measurements of relative humidity and water balances without using any analytical methods. In order to test the performance of the on-line conversion estimation, the lipase-catalyzed esterification of n-capric acid and n-decal alcohol in solvent-free media was performed whilst controlling water activity at various values. The reaction conversions estimated on-line were similar to those determined by offline gas chromatographic analysis. However, when the water activity was controlled at higher values, discrepancies between the estimated conversion values and the measured values became significant. The deviation was found to be due to the inaccurate measurement of the water content in the reaction medium during the initial stages of the reaction. Using a digital filter, we were able to improve the accuracy of the on-line conversion estimation method considerably. Despite the simplicity of this method, the on-line estimated conversions were in good agreement with the off-line measured values.

• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.16-21
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• 2008

The key component of a direct methanol fuel cell (DMFC) is the membrane electrode assembly (MEA), which comprises a polymer electrolyte membrane and catalyst layers (anode and cathode electrode). Generally the catalyst layer is coated on the porous electrode supporter (e.g. carbon paper or cloth) using various coating methods such as brushing, decal transfer, spray coating and screen printing methods. However, these methods were disadvantageous in terms of the uniformity of catalyst layer thickness, catalyst loss, and coating time. In this work, we used bar-coating method which can prepare the catalyst layer with uniform thickness for MEA of DMFC. The surface and cross-section morphologies of the catalyst layers were observed by SEM. The performances and resistance of the MEAs were investigated through a single cell evaluation and impedance analyzer.

• Journal of Electrochemical Science and Technology
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• v.10 no.1
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• pp.22-28
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• 2019

To maximize the oxygen evolution reaction (OER) in the electrolysis of water, nano-grade $IrO_2$ powder with a low specific surface was prepared as a catalyst for a solid polymer electrolyte (SPE) system, and a membrane electrode assembly (MEA) was prepared with a catalyst loading as low as $2mg\;cm^{-2}$ or less. The $IrO_2$ catalyst was composed of heterogeneous particles with particle sizes ranging from 20 to 70 nm, having a specific surface area of $3.8m^2g^{-1}$. The anode catalyst layer of about $5{\mu}m$ thickness was coated on the membrane (Nafion 117) for the MEA by the decal method. Scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) confirmed strong adhesion at the interface between the membrane and the catalyst electrode. Although the loading of the $IrO_2$ catalyst was as low as $1.1-1.7mg\;cm^{-2}$, the SPE cell delivered a voltage of 1.88-1.93 V at a current density of $1A\;cm^{-2}$ and operating temperature of $80^{\circ}C$. That is, it was observed that the over-potential of the cell for the oxygen evolution reaction (OER) decreased with increasing $IrO_2$ catalyst loading. The electrochemical stability of the MEA was investigated in the electrolysis of water at a current density of $1A\;cm^{-2}$ for a short time. A voltage of ~2.0 V was maintained without any remarkable deterioration of the MEA characteristics.