• KSBB Journal
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• v.8 no.5
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• pp.457-464
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• 1993

In this study, an attempt was made to investigate optimum cell growth and products by Bacillus amyloliquefaciens 23350 in batch culture by varing carbon soures. Maximum dry cell density increased with the increase of initial glucose concentration. Maximum dry cell density was obtained with the highest value of 5.2g/l at 30g/l of initial glucose concentration. By adding acetic acid at 20g/l of initial glucose concentration, the cell growth rate decreased with the increase of initial acetic acid concentration. Among the various carbon sources, maximum $\alpha$-amylase production was obtained with 225unit/ml at 10g/1 of initial glucose concentration. Optimum production of $\alpha$-amylase was obtained with 376unit/ml at 2g/l of initial acetic acid concentration and 20g/l of initial glucose concentration. By 10g/1 of initial glucose concentration, both good maximum specific cell growth rate and maximum $\alpha$-amylase production rate were obtained. In view of the results studied optimum production and specific production rate of $\alpha$-amylase, acetic acid was initially added 2~4g/l with 20g/1 of initial glucose concentration in batch culture.

• Korean Journal of Materials Research
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• v.21 no.12
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• pp.639-643
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• 2011

Zinc oxide as an optoelectronic device material was studied to utilize its wide band gap of 3.37 eV and high exciton biding energy of 60 meV. Using anti-site nitrogen to generate p-type zinc oxide has shown a deep acceptor level and low solubility. To increase the nitrogen solubility in zinc oxide, group 13 elements (aluminum, gallium, and indium) was co-added to nitrogen. The effect of aluminum on nitrogen solubility in a $3{\times}3{\times}2$ zinc oxide super cell containing 72 atoms was investigated using density functional theory with hybrid functionals of Heyd, Scuseria, and Ernzerhof (HSE). Aluminum and nitrogen were substituted for zinc and oxygen sites in the super cell, respectively. The band gap of the undoped super cell was calculated to be 3.36 eV from the density of states, and was in good agreement with the experimentally obtained value. Formation energies of a nitrogen molecule and nitric oxide in the zinc oxide super cell in zinc-rich conditions were lower than those in oxygen-rich conditions. When the number of nitrogen molecules near the aluminum increased from one to four in the super cell, their formation energies decreased to approach the valence band maximum to some degree. However, the acceptor level of nitrogen in zinc oxide with the co-incorporation of aluminum was still deep.

• Journal of Sensor Science and Technology
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• v.23 no.6
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• pp.388-391
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• 2014

The most promising application of the biofuel cells is implantable devices, so the biofuel cells should have an appropriate shape for the vascular vessel. We demonstrated the biofuel cell roll for using in tubes. MWNTs were aggregated by vacuum filtration on a nitrocellulose membrane filter, which was biocompatible and flexible. The MWNT aggregated nitrocellulose membrane used the electrodes of the biofuel cells because it was conductive as well as nanostuructured. Then, the membrane was rolled into the roll shape. The maximum power density of the biofuel cell roll was $7.9{\mu}W/cm^2$ at 153mV and 50 mM glucose. Also, the power density is expected to increase in its practical application if there is flow in the tube, which makes the transportation of fuel easy. The biofuel cell roll contacts with the wall of the tube, so flow in the tube does not disturb. Also, the biofuel cell roll has multi-layers offering more electroactive area.

• Microbiology and Biotechnology Letters
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• v.22 no.1
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• pp.80-84
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• 1994

In order to induce the rapid alcohol fermentation through the increases of the cell density in a continuous alcohol fermentation of naked barley, the single-cultivation with S. cerevisiae IS-019(SCM, ordinary control), mixed-cultivation with Saccharomyces uvarum IS-026 having a flocculent ability and S. cerevisiae IS-019(MCM), and mash recirculation by single-cultivation of S. cerevisiae IS-019(MRM) modes were investigated. The cell mass in the mixed-cultivation mode was about 10% higher than that of ordinary control but the final alcohol yield was slightlyl decreased. When recycled the mash with the flow rate of 7 l/h from V$_{6}$ to V$_{5}$ fermentors under the ordinary control, the cell density was distributed at 140~170$\times $10$^{6}$ cell/ml depending upon the fermentorsorders, higher about 20% than that of the ordinary control. Under these conditions the alcohol productivity of the maximum and the overall was 12.16 g/l$\cdot $h with an alcohol of 7.6% at the V$_{5}$ fermentor and 1.19 g/l$\cdot $h with an alcohol of 8.94%, respectively. For higher cell mass it was more effective to apply the mash recirculation mode with the single-cultivation of S. cerevisiae IS-019 in a pilot scale multi-stage CSTR.

• Journal of Environmental Science International
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• v.21 no.1
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• pp.105-111
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• 2012

The effects of substrate size on the growth of microphytobenthos Achnanthes sp., Amphora sp., Navicula sp. and Nitzschia sp. were examined using glass beads in order for phytoremediation in the benthic layer of coastal waters. The glass beads used in this study were 0.09~0.15 mm (G.B 1), 0.25~0.50 mm (G.B 2), 0.75~1.00 mm (G.B 3) and 1.25~1.65 mm (G.B 4). No addition of glass bead used as control. The specific growth rate and maximum cell density of four microphytobenthos species were increasing with decreasing size of glass beads. Moreover, the control experiment without added attachment substrates showed the lowest specific growth rate and maximum cell density. Therefore, the suitable attachment substrates for mass culture of microphytobenthos seems to be important in order for phytoremediation using microphytobenthos.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11C
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• pp.1052-1057
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• 2006

The implement the adaptive partial response maximum likelihood (PRML) detector with tilt analyzer for asymmetric high-density optical storage system. For the estimation of disc tilt, we exploit spc patterns in each data frame. Because of using the ROM table to renew the coefficients of equalizer and reference values of branches, the complexity of the hardware is reduced. The proposed PRML has been designed and verified by VerilogHDL and synthesized by the Synopsys Design Compiler with Hynix $0.35{\mu}m$ STD cell library. In the result, the total gate count is 35K, and the maximum operating frequency is 140MHz.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.10
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• pp.95-101
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• 2021

An analysis was conducted to predict the behavior of gasket by applying an optimal-strain energy-density function selected through a uniaxial tensile test and an analysis of the gasket used in an actual hydrogen fuel cell. Among the models compared to predict the materials' properties, the Mooney-Rivlin secondary model showed the behavior most similar to the test results. The maximum stress of the gasket was not significantly different, depending on the location. The maximum surface pressure of the gasket was higher at positions "T" and "Y" than at other positions, owing to the branch-shape effect. In the future, a jig that can measure the surface pressure will be manufactured and a comparative verification study will be conducted between the test results and the analysis results.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.373-378
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• 2021

The study aimed to develop a high-power enzymatic electrode for a wearable fuel cell that generates electricity utilizing lactate present in a sweat as fuel. Anode was fabricated by immobilizing lactate oxidase (LOx) on flexible carbon paper. As the lactate concentration in the electrolyte solution increased, the amount of current generated by catalysis of lactate oxidase increased. The immobilized LOx generated 1.5-times greater oxidation current density in the presence of gold nanoparticles than carbon paper only. Bilirubin oxidase (BOD)-immobilized cathode generated a larger amount of reduction current in the electrolyte saturated with oxygen than purged with nitrogen. A fuel cell composed of two electrodes was fabricated and cell voltage was measured under different discharge current. At the discharge current density of 66.7 ㎂/cm², the cell voltage was 0.5±0.0 V leading to maximum cell power density of 33.8±2.5 ㎼/cm².

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.6
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• pp.529-536
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• 2008

Cyanobacteria Synechocystis PCC 6803 or the extracted thylakoid membrane from this strain was appled to photosynthetic bio-electrochemical fuel cell(PBEFC) for the production of hydrogen under the illumination of 48Klux using halogen lamp. PBEFC was composed of anode, cathode and membrane between them. Electrode material was carbon paper while electron mediator and receptor were added phenazine methosulfate(PMS) and potassium ferricyanide respectively. When water and 50 mM tricine buffer and $300{\mu}M$ PMS were added to the anode under the light condition, PBEFC produced the current density $4.4{\times}10^{-5}\;mA/cm^2$, $1.4{\times}10^{-4}\;mA/cm^2$ and $2.4{\times}10^{-4}\;mA/cm^2$, respectively. And the addition of the thylakoid membrane to the system increased current density to $1.3{\times}10^{-3}\;mA/cm^2$. Two times increase of the thylakoid membrane into the anode doubled the current density to $2.6{\times}10^{-3}\;mA/cm^2$. But the current density was not increased proportionally to the amount of thylakoid membrane increased. The system was unstable to measure the electricity output due to the foam production in the anode. Addition of triton X-100 and tween 80 stabilized the system to measure the electricity output but the current density was not increased higher than $8.4{\times}10^{-4}\;mA/cm^2$ and $2.3{\times}10^{-3}\;mA/cm^2$. When the thylakoid membrane was substituted to Synechocystis PCC 6803 cells of four-day culture which has chlorophyll contents $20.5{\mu}g/m{\ell}$, maximum current density was $1.3{\times}10^{-3}\;mA/cm^2$ with $1\;k{\Omega}$ resistance.

• KSBB Journal
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• v.4 no.1
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• pp.18-20
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• 1989

Solid gelatin microcarrier with the size distribution between $100{\mu}{\textrm}{m}$ and $400{\mu}{\textrm}{m}$ was prepared for the attachment and growth experiment for anchorage-dependent animal cell lines, i.e., L 929 and BHK 21. The growth and the maximum cell densities on this gelatin based and polyacrylamide (PAA) microcarriers were compared with those on the commercial dextran based Cytodex 3 microcarrier. Both cell lines showed good comparable attachment and growth patterns on the above three microcarriers. The mouse fibroblast, L 929 showed about the same maximum cell density on PAA, gelatin and Cytodex 3 MC'S BUT BHK 21, the baby hamster kidney cell line, showed the best result on Cytodex 3, which was about $4\times10^6$ cells/ml with the microcarrier concentration of 10 g/1.