• Korea-Australia Rheology Journal
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• v.20 no.2
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• pp.89-94
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• 2008

To satisfy good mechanical and optical properties of polymer-coated film products, it will be indispensable to elucidate the molecular orientation of polymer chains within coating liquids in coating flows. Using hybridized numerical method between computational fluid dynamics (CFD) and Brownian dynamics (BD) simulations can provide the useful information for the better quality control of coated films. Flexible polymer chains, e.g., ${\lambda}$-DNA molecules here, change their conformation according to the flow strength and the flow type. The molecular conformation within the coated film on the web or substrate is quite different, because the polymer chains experience the complicated flow strength and flow types in flow field. Especially in the slot coating flow, these chains are more extended by the extension-like flow field generated in the free surface curvature just beyond the downstream die region. Also, the polymer chain extension beneath the free surface can be affected by the die geometry, e.g., the coating gap, changing flow field.

• Journal of the Korean Society for Heat Treatment
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• v.22 no.1
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• pp.16-22
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• 2009

The rolling process is an efficient and economical approach for the manufacturing of plate metals. In the rolling process, the temperature variation is very critical for plate thickness accuracy. The main cause of thickness variation in hot plate mills is the non-uniform temperature distribution along the length of the slab. Also the exit plate thickness is mainly affected by the rolling conditions such as mill modulus, plate thickness and plate width. Hence the thickness variation in top-end is also dependent on these factors. Therefore this study has concentrated on determining the correct amounts of thickness variation due to top-end temperature drop and process parameters.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.4
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• pp.330-338
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• 2002

A long-term energy system in the future is expected to be based on the ideal circulation system between water and hydrogen in the sense that the hydrogen prepared from water eventually returns to water again after its use. Currently, with respect to the hydrogen energy system, it is predicted that the turning-point at which the production cost of hydrogen will become to be lower than that of fossil fuels would be after 2010. However, fuel cell technology would be able to be practically used for the applications to the transportation vehicles and small-scale power sources from 2004, and therefore, an efficient construction of the infrastructure covering hydrogen production and supply systems would be required with short-/mid-term technologies for the $CO_2$ reduction associated with fossil fuel utilization. In this paper, the hydrogen quantity available in domestic market has been estimated focusing on the hydrogen by-produced from domestic industries, and also the infrastructure for hydrogen-driven vehicles like fuel cell cars has been reviewed.

• Rapid Communication in Photoscience
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• v.4 no.4
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• pp.82-85
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• 2015

Photoelectrochemical cell (PEC) is one of the attractive ways to produce clean and renewable energy. However, solar to hydrogen production via PEC system generally requires high external bias, because of material's innate electronic band potential relative to hydrogen reduction potential and/or charge separation issue. For spontaneous photo-water splitting, here, we design dye-sensitized solar cell (DSSC) and their monolithic tandem cell incorporated with a $BiVO_4$ photoanode. $BiVO_4$ has high conduction band edge potential and suitable band gap (2.4eV) to absorb visible light. To achieve efficient $BiVO_4$ photoanode system, electron and hole mobility should be improved, and we demonstrate a tandem cell in which $BiVO_4/WO_3$ film is connected to cobalt complex based DSSC.

• Preventive Nutrition and Food Science
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• v.14 no.1
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• pp.29-36
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• 2009

To compare antioxidative and antiaging effects between yellow soybean (YS) and Chungkukjang (CK) in vivo system, male Sprague-Dawley rats (n=24) were fed the diets containing YS and CK for 8 weeks, respectively. The YS and CK groups showed the preventive effects on lipid and protein oxidations in liver and plasma. Hepatic SOD and GSH-peroxidase activities were significantly inhibited in CK group. Superoxide anion radicals in cytosol significantly lowered in YS and CK groups compared with control group. In addition, dietary YS and CK effectively inhibited formation of the lipofuscin, the indicator of aging in heart and eye, especially the CK group had a stronger preventive activity in eye. The results of this study showed that YS and CK diet effectively suppressed the superoxide anion radical formation and tissue oxidation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.185-188
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• 2004

A diode structure of field emission lamps based upon carbon-nanotube is studied. The single-walled carbon nanotubes(SWNTs) were produced by arc discharge method. We made the 1-inch diode type flat lamp using CNTs. We applied anode voltage gradually to refine the field emission behavior of emitter in dynamic vacuum system to study the emission current. the brightness and efficiency, etc. The field emission properties was estimated by varying gaps between the cathode and anode, contents of the glass frit. The good luminous efficiency is showed in the gap $900{\mu}m$, $1200{\mu}m$ and contents of the proper glass frit. For the upper conditions, the luminous efficiencies were respectively 23.30, 11.12 1m/W.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.4
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• pp.395-401
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• 2014

Magnetic levitation systems using the attraction force of electromagnets have many constraints according to the variation of air gap and the nonlinearity of electromagnetic force and inductances. As a result of these constraints, the nonlinear control of a magnetic levitation system has been improved by the latest advanced processors and accurate measurement system which can overcome problems such as many constraints and nonlinearity. This paper concentrates on the modeling of a nonlinear magnetic levitation system and an application of an exponential reaching law based sliding mode controller using the exponential reaching law which is one of the most robust controllers against external unexpected disturbances or parameter fluctuations. Controllability of a magnetic levitation system using the sliding mode control algorithm and robustness against parameter fluctuations have been verified through the experimental results.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.181-181
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• 2012

The microwave probe for measuring plasma density is widely used for its advantages: First, it is not affected by the reactive gas. Second, it can measure local plasma parameters such as plasma density, plasma potential and plasma temperature. Third, it is simple and robust. A cut-off probe is the one of the most promising microwave probe. Recently, Kim et al. reveals the physics of the cut-off probe but the effect of the sheath on the determination of the plasma density is not explained. In this presentation, for taking account of sheath effects on determination of plasma density from the cut-off peak, a simplified circuit modeling and an E/M simulation are conducted. The results show that occupation ratio of sheath volume between two tips of the cut-off probe and subsequence pressure condition mainly change position of the cut-off peak with respect to plasma frequency. Magnitude of relative voltage taken on the impedance of sheath and the impedance of bulk plasma can explain this effect. Furthermore, effects of gap size, tip radius, and tip length ware revealed based on above analysis.

• Korean Institute of Interior Design Journal
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• v.23 no.1
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• pp.162-171
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• 2014

This study aimed to evaluate how universal design principles are embodied in the village community center. It will provide preliminary data on constructing a physical space of village community center as small community space in agricultural districts. To achieving the purpose in this study, the research conducted inspection using checklist to 25 village community centers at Hwasoon, Jeonnam province. The conclusion of this study is as follows: Living room and kitchen/dining room by supportive design urgently need installation of Western Style furniture and solutions of stair gap by accessible design, and also the evaluation is unsuited on a fire-gas alarm system and prevention of electric shook system on safety-oriented design. Entrance evaluated in principle for insufficient on safety handle by supportive design and spare chair by adaptable design, and also it unsuited on the solutions of door sill by accessible design and non-skid by safety-oriented design. Bathroom is insufficient lever handle and safety grip by supportive design, sink isn't suitable by adaptable design. Outdoor space information legislation staircase ramp installation and horizontal installation of the staircase was not built.

• Transactions on Electrical and Electronic Materials
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• v.7 no.6
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• pp.279-282
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• 2006

[ $Pb(Zr_{0.4}Ti_{0.6}O_{3}\;and\;Pb(Zr_{0.6}Ti_{0.4})O_{3}$ ] paste were made and alternately screen-printed on the $Al_{2}O_{3}$ substrates. We have introduced a press-treatment to obtain a good densification of screen printed films. The porosity of the thick films was decreased with increasing the applied pressure and the thick films pressed at 60 MPa showed the dense microstructure and thickness of about $76\;{\mu}m$. The remanent polarization and coercive field increased with increasing applied pressure and the values for the PZT thick films pressed at 60 MPa were $17.04{\mu}C/cm^{2}$ and 78.09 kV/cm, respectively.