• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.731-736
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• 2014

An organic junction transistor with a vertical structure based on an active layer of poly(3-hexylthiophene) was fabricated by facile micro-contact printing combined with the Langmuir-Schaefer technique, without conventional e-beam or photo-lithography. Direct printing and subsequent annealing of Au-nanoparticles provided control over the thickness of the Au electrode and hence control of the electrical contact between the Au electrode and the active layer, ohmic or Schottky. The junction showed similar current-voltage characteristics to an NPN-type transistor. Current through the emitter was simply controllable by the base voltage and a high transconductance of ~0.2 mS was obtained. This novel fabrication method can be applied to amplifying or fast switching organic devices.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.5
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• pp.352-358
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• 2001

Because algal cells are so efficient at absorbing incoming light energy, providing more light energy to photobioreactors would simply decrease energy conversion efficiency. Furthermore, the algal biomass productivity in photobioreactor is always proportional to the total photosynthetic rate. In order to optimize the productivity of algal photobioreactors (PBRs), the oxygen production rate should be estimated. Based on a simple model of light penetration depth and algal photosynthesis, the oxygen production rate in high-density microalgal cultures could be calculated. The estimated values and profiles of oxygen production rate by this model were found to be in accordance with the experimental data. Optimal parameters for PBR operations were also calculated using the model.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1401-1403
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• 2008

Considering that human body is continuously experiencing mechanical stimuli due to daily activities, the micro-physical environments of cells/tissues should be considered for the successful outcomes in tissue engineering and/or related researches. Obviously, there are many factors involved in cell-based researches. In this presentation, the current trends and some of outcomes are introduced. Through this studies, the roles of mechanical engineering in relation to medical/biological researches are to be emphasized.

• Proceedings of the Microbiological Society of Korea Conference
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• 2007.05a
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• pp.123-126
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• 2007

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.3
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• pp.186-190
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• 2000

It has been reported that flashing light enhances microalgal biomass productivity and overall photosynthetic efficiency. The algal growth kinetics and oxygen production rates under flashing light with various flashing frequencies (5Hz-37 kHz) were compared with those under equivalent continuous light in photobioreactors. A positive flashing light effect was observed with flashing frequencies over 1kHz. The oxygen production rate under conditions of flashing light was slightly higher than that under continuius ligth. The cells under the hight, particularly at higher cell concentrations. When 37kHz flashing light was applied to an LED-based photobioreactor, the concentration was higher than that obtained under continuous light by about 20%. Flashing light may be a reasonable solution to overcome mutual shading, particularly in high-density algal cultures.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.5
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• pp.391-395
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• 2006

Microcapsules containing fragrant oils as a core material were prepared by in situ polymerization, using melamine-formaldehyde prepolymer as the wall material. The several parameters, such as stirring times, stirring rates, emulsifier types, emulsifier concentrations, and the viscosity of the core materials, affect the characteristics of the microcapsules. These parameters were investigated by the analyses of microcapsule size, particle size distribution, and morphology. The average microcapsule size decreased with an increase in stirring time, stirring rate, emulsifier concentration, and viscosity of the core material. It was also found that poly(vinyl alcohol) as a protective colloid could enhance the stability of the melamine-formaldehyde microcapsules.

• Biotechnology and Bioprocess Engineering:BBE
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• v.2 no.2
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• pp.69-72
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• 1997

The pH of microbial culture medium was calculated from equations of equilibrium, meterial balances for ionic components and electro-neutrality theory. Ammonium ion consumption and Acetic acid production are found out to be the major contributors for the alteration of the pH as well as the buffer capacity of the medium. By measuring the buffer capacity on-line, levels of acetic acid were estimated by a software sensor using pH signal in a fermentation process of E.coli growing in a minimal medium. The measured values of acetic acid showed good correlation to those of estimated by the software sensor.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.257-258
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• 1998

To reveal the interconnected brain regions involved in human working memory, their functional connectivity was analyzed using principal component analysis (PCA). rCBF PET scans were peformed on 5 normal volunteers during the verbal and visual working memory tasks and PCA was applied. PCA produced the first principal components related with the increase of the difficulty and the second one which demonstrate the dissociation of verbal and visual memory system.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.72-73
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• 1998

A new method for enzyme immobilization has been developed to remove interference by potential interferents in body fluids. Instead of using electron mediators, we chose direct hydrogen peroxide measurement route. Extremely hydrogen peroxide-selective polymer was coated as an inner membrane to exclude interferents and then glucose oxidase(GOx) was entrapped by electropolymerization of inert monomers. There was no solvent casting step throughout the whole fabrication procedure but all membranes on Pt-Ir electrode were formed by electropolymerization. Thus, membrane thickness, quantity of enzyme loaded and can be controlled by electrochemical parameters. As a result, reproducibility of biosensor characteristics becomes remarkably improved in terms of mass production.

• Applied Biological Chemistry
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• v.23 no.2
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• pp.106-114
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• 1980

The flavor constituents of Korean Milgam were extracted with a nitrogen gas stream under partial vacuum and identified by gas liquid chromatography. By employing the extraction coefficient, it was possible to determine the concentration of components in Milgam as well as in the extracts. Among 53 GLC peaks, 26 components were identified. Ethanol was the most abundant component (140ppm), followed by limonene (120ppm). These two were the most important flavor constituents.