• Journal of Energy Engineering
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• v.29 no.1
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• pp.58-62
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• 2020

Among the exhaust gas, Carbon dioxide which is a causative factor in greenhouse effect. We study for synthesis of propylene carbonate with carbon dioxide which is captured and utilized in commercially valuable. The Experiment was proceeded as pilot scale with using homogeneous organic catalyst which is able to produce propylene carbonate in commercial and reaction conditions. Optimization condition for concentration of catalyst and reaction temperature, pressure was studied. We confirm that this process is eco-friendly method and commercial application due to the mild condition and also catalyst has a competitive price, reusability.

• Macromolecular Research
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• v.17 no.9
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• pp.646-650
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• 2009

We report the fabrication of pentacene organic field-effect transistors (OFETs) using a fluorinated styrene-alt-maleic anhydride copolymer gate dielectric, which was prepared from styrene derivatives with a fluorinated side chain [$-CH_2-O-(CH_2)_2-(CF_2)_5CF_3$] and maleic anhydride through a solution polymerization technique. The fluorinated side chain was used to impart hydrophobicity to the surface of the gate dielectric and maleic anhydride was employed to improve its wetting properties. A field-effect mobility of 0.12 cm$^2$/Vs was obtained from the as-prepared top-contact pentacene FETs. Since various functional groups can be introduced into the copolymer due to the nature of maleic anhydride, its physical properties can be manipulated easily. Using this type of copolymer, the performance of organic FETs can be enhanced through optimization of the interfacial properties between the gate dielectric and organic semiconductor.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.67.1-67.1
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• 2012

Graphene has attracted much attention for future nanoelectronics due to its superior electrical properties. Owing to its extremely high carrier mobility and controllable carrier density, graphene is a promising material for practical applications, particularly as a channel layer of high-speed FET. Furthermore, the planar form of graphene is compatible with the conventional top-down CMOS fabrication processes and large-scale synthesis by chemical vapor deposition (CVD) process is also feasible. Despite these promising characteristics of graphene, much work must still be done in order to successfully develop graphene FET. One of the key issues is the process technique for gate dielectric formation because the channel mobility of graphene FET is drastically affected by the gate dielectric interface quality. Formation of high quality gate dielectric on graphene is still a challenging. Dirac voltage, the charge neutral point of the device, also strongly depends on gate dielectrics. Another performance killer in graphene FET is source/drain contact resistance, as the contact resistant between metal and graphene S/D is usually one order of magnitude higher than that between metal and silicon S/D. In this presentation, the key issues on graphene-based FET, including organic-inorganic hybrid gate dielectric formation, controlling of Dirac voltage, reduction of source/drain contact resistance, device structure optimization, graphene gate electrode for improvement of gate dielectric reliability, and CVD graphene transfer process issues are addressed.

• Journal of Powder Materials
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• v.20 no.3
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• pp.191-196
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• 2013

Nano-sized cobalt powder was fabricated by wet chemical reduction method at room temperature. The effects of various experimental variables on the overall properties of fabricated nano-sized cobalt powders have been investigated in detail, and amount of NaOH and reducing agent and dropping speed of reducing agent have been properly selected as experimental variables in the present research. Minitab program which could find optimized conditions was adopted as a statistic analysis. 3D Scatter-Plot and DOE (Design of Experiments) conditions for synthesis of nano-sized cobalt powder were well developed using Box-Behnken DOE method. Based on the results of the DOE process, reproducibility test were performed for nano-sized cobalt powder. Spherical nano-sized cobalt powders with an average size of 70-100 nm were successfully developed and crystalline peaks for the HCP and FCC structure were observed without second phase such as $Co(OH)_2$.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.8
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• pp.598-608
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• 2002

This paper shows the optimal design methodology for the fluid engine mount by the artificial life algorithm. The design has been commonly modified by trial and error because there is many design parameters that can be varied in order to minimize transmissibility at the desired fundamental resonant and notch frequencies. The application of trial and error method to optimization of the fluid mount is a great work. Many combinations of parameters are possible to give us the desired resonant and notch frequencies, but the question is which combination Provides the lowest resonant peak and notch depth. In this study the enhanced artificial life algorithm is applied to get the desired fundamental resonant and notch frequencies of a fluid mount and to minimize transmissibility at these frequencies. The present hybrid algorithm is the synthesis of and artificial life algorithm with the random tabu (R-tabu) search method. The hybrid algorithm has some advantages, which is not only faster than the conventional artificial life algorithm, but also gives a more accurate solution. In addition, this algorithm can find all globa1 optimum solutions. The results show that the performance of the optimized mount compared with the original mount is improved significantly.

• Bulletin of the Korean Chemical Society
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• v.30 no.6
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• pp.1297-1304
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• 2009

A novel series of imidazo[1,2-$\alpha$]pyridines was designed, synthesized, and tested for their ability to inhibit acyl- CoA:cholesterol acyltransferase. Preliminary lead optimization efforts resulted in the identification of ACAT inhibitors represented by analogues 5b, 5c, 6a, 6c, 7b, and 7c. The ACAT inhibitory activity of these compounds was further established by potent inhibition of cholesteryl ester formation in HepG2 cells by a representative analogue 7b.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.627-635
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• 2020

3D printing technology is a processing technology in which 3D structures are formed by fabricating multiple 2D layers of materials based on 3D designed digital data and stacking them layer by layer. Although layers are stacked using inkjet printing to release various materials, it is still rare for research to successfully form a product as an additive manufacture of multi-materials. In this study, dispersion conditions are optimized by adding a dispersant to an acrylic monomer suitable for inkjet printing using Co₃O₄ and Al₂O₃. 3D structures having continuous composition composed of a different ceramic material are manufactured by printing using two UV curable ceramic inks whose optimization is advanced. After the heat treatment, the produced structure is checked for the formation and color of the desired crystals by comparing the crystalline analysis according to the characteristics of each part of the structure with ceramic pigments made by solid phase synthesis method.

• Electrical & Electronic Materials
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• v.8 no.6
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• pp.780-786
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• 1995

For the execution of RIETAN program adopting Rietveld Analysis Method, the sample superconductor is made according to the solid state synthesis method at 920.deg. C for 24hrs, and was examined for the optimization of parameters needed to analyze Rietveld method with the input of the measured pattern data after measuring the pattern resulted from the X-ray diffraction. It was proven that the lattice constant of the superconductor which was consisted of Pmmm orthorhombic crystal structure in the analyzed space group correspond to the presented theoretical lattice constant a=3.8887(8).angs., b=3.8238(4).angs., c=11.7079.angs.. Therefore, it was examined and confin-ned that the R factor, which was compensated after analyzing the structure of superconductor resulted from this experimented data with the computer simulation, was refined to $R_{wp}$=8.83[%], $R_{P}$=6.47[%], $R_{I}$=10.08[%], $R_{F}$=7.19[%], $R_{E}$=3.76[%]. On the basis of these experimental data, the significant parameter such as the scale factor(S) and the zero point shift(Z) and FWHM value(U,V,W) were optimized as follows; S=2.0827E-3, Z=0.2146, U=4.2761E-2, V=1.7983E-2, and W=2.6768E-2.2.2.2.2.2.

• Journal of Microbiology and Biotechnology
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• v.26 no.8
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• pp.1348-1357
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• 2016

An enzymatic reaction system was developed and optimized for bioconversion of resveratrol from glucose. Liquid enzyme extracts were prepared from Alternaria sp. MG1, an endophytic fungus from grape, and used directly or after immobilization with sodium alginate. When the enzyme solution was used, efficient production of resveratrol was found within 120 min in a manner that was pH-, reaction time-, enzyme amount-, substrate type-, and substrate concentration-dependent. After the optimization experiments using the response surface methodology, the highest value of resveratrol production (224.40 μg/l) was found under the conditions of pH 6.84, 0.35 g/l glucose, 0.02 mg/l coenzyme A, and 0.02 mg/l ATP. Immobilized enzyme extracts could keep high production of resveratrol during recycling use for two to five times. The developed system indicated a potential approach to resveratrol biosynthesis independent of plants and fungal cell growth, and provided a possible way to produce resveratrol within 2 h, the shortest period needed for biosynthesis of resveratrol so far.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.12
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• pp.767-775
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• 2014

New material design has obtained tremendous attention in material science community as the performance of new materials, especially in nano length scale, could be greatly improved to applied in modern industry. In certain conditions limiting experimental synthesis of these new materials, new approach by computer simulation has been proposed to be applied, being able to save time and cost. Recent development of computer systems with high speed, large memory, and parallel algorithms enables to analyze individual atoms using first principle calculation to predict quantum phenomena. Beyond the quantum level calculations, mesoscopic scale and continuum limit can be addressed either individually or together as a multi-scale approach. In this article, we introduced current endeavors on material design using analytical theory and computer simulations in multi-length scales and on multi-physical properties. Some of the physical phenomena was shown to be interconnected via a cross-link rule called 'cross-property relation'. It is suggested that the computer simulation approach by multi-physics analysis can be efficiently applied to design new materials for multi-functional characteristics.