• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.324-329
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• 2004

Oxygen diffuses through the cation-specific membrane, reducing the coulomb yield of the fuel cell. In the present study, attempts were made to enhance current generation from the fuel cell by lowering the oxygen diffusion, including the uses of ferricyanide as a cathode mediator and of a platinum-coated graphite electrode. Ferricyanide did not act as a mediator as expected, but as an oxidant in the cathode compartment of the microbial fuel cell. The microbial fuel cell with platinum-coated graphite cathode generated a maximum current 3-4 times higher than the control fuel cell with graphite cathode, and the critical oxygen concentration of the former was 2.0 mg $1^{-1}$, whilst that of the latter was 6.6 mg $1^{-1}$. Based on these results, it was concluded that inexpensive electrodes are adequate for the construction of an economically feasible microbial fuel cell with better performance as a novel wastewater treatment process.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.947-953
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• 2002

Two types of electronic nose were used for investigating the quality of dried lavers stored at 5, 15, and $30^{\circ}C$ RH of 32, 43, and 75%. The electronic nose is composed of metal oxide sensors, and GC is based on SAW sensor. Quality change in dried lavers was described in terms of the sensitivities $(R_{gas}/R_{air})$ of the sensors. Principal component analysis (PCA) was carried out using data obtained from six metal oxide sensors. The first principal component scores were correlated with quality changes of dried lavers. As storage time increased, the stored laver cluster separated from that of fresh lavers. A chromatogram was obtained from GC based on SAW sensor. Olfactory image, A $VaporPrint^{TM}$ image for pattern recognition, showed a significant difference between the stored and the fresh samples. Dried lavers during storage at $30^{\circ}C$ and 75% had bacterial counts of $5.7{\times}10^6\;CFU/g$ after 8 day. Increase of microbial count correlated with the response of electronic nose $(r^2=0.87)$. Whereas, color values showed no correlation.

• Journal of Sensor Science and Technology
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• v.9 no.2
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• pp.127-133
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• 2000

We propose a novel monitoring system for a recycling piggery slurry treatment system through neural networks. Here we tried to model treatment process for each tank(influent, fermentation, aeration, first sedimentation and fourth sedimentation tanks) in the system based on population densities of heterotrophic and lactic acid bacteria. Principle component analysis(PCA) was first applied to identify a relation between input(microbial densities and parameters for the treatment) and output, and then multilayer neural networks were employed to model the treatment process for each tank. PCA filtration of input data as microbial densities was found to facilitate the modeling procedure for the system monitoring even with a relatively lower number of input. Neural networks independently trained for each treatment tank and their subsequent combinatorial data analysis allowed a successful prediction of the treatment system for at least two days.

• Analytical Science and Technology
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• v.7 no.3
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• pp.285-291
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• 1994

A microbial BOD sensor for the continuous estimation of BOD was been developed by immobilizing Trichosporon cutaneum, which was immobilized between a dialysis and a gas-permeable membrane, on an oxygen electrode. The optimum pH and temperature for BOD measurement using this sensor were pH 7.0 and $32{\sim}33^{\circ}C$, respectively. The best result was obtained at 2~3ml/min flow rate in 0.1M phosphate buffer solution. A linear relationship was observed between ${\Delta}DO$ and the concentration of standard GGA solution below 60mg/l(90ppm $BOD_5$). The reproducibility was found to be within 3% for the standard solution containing glucose 30mg/l and glutamic acid 30mg/l. The output DO value of this sensor was almost constant for 30 dalys. The response time and the recovery time were about 5 and 10 min, respectively. This sensor was employed for the BOD measurement of waste pollutants and was compared with $BOD_5$ method.

• Journal of Microbiology and Biotechnology
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• v.9 no.3
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• pp.365-367
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• 1999

A fuel cell type biosensor for lactate was developed using a metal-reducing bacterium, Shewanella putrefaciens IR-1. Under the operational conditions, the bacterial cell suspension generated the current without an electrochemical mediator in the presence of lactate. The current was proportional to the lactate concentration up to 30 mM.

• Korean Journal of Food Science and Technology
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• v.34 no.1
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• pp.136-139
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• 2002

The discrimination of the agricultural origin, especially locally produced of imported products such as black rices was investigated by using electronic nose. Volatile components from these products were discriminated by six metal oxide sensors without pretreatment. Pattern recognition was carried out. Principal component analysis showed the differences between imported and locally produced ones. The number of 57 from 69 species of black rices were recognized as locally produced one (83.33%) and 11 from 13 species one (imported black rices) was correctly discriminated. Unknown habitat of black rice could be identified by artificial neural network system whether the imported or not. Also commercial electronic nose (E-nose 5000) that was combined with metal oxide sensor and conducting polymer sensor showed 92.75% (locally produced black rices) and 92.31% (imported one) of discrimination.

• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.994-997
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• 2003

Domestic and imported Cnidium officinale were investigated using GC based on a SAW sensor. Volatile components from the herb were detected by GC with a Surface Acoustic Wave (SAW sensor without any pretreatment. This system produced a frequency proportional to the amount of column effluent deposited on the SAW sensor. It could discriminate between domestic and imported Cnidium officinales. This was achieved by using a pattern recognition and a visual pattern called a $VaporPrint^{TM}$, derived from the frequency and chromatogram of the GC-SAW sensor. The origins of Cnidium officinale was well discriminated with the direct use of $VaporPrint^{TM}$.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.144-148
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• 2003

Volatile components were detected from domestic and imported Angelica gigas Nakai without any pretreatment using GC based on Surface Acoustic Wave (SAW) sensor. This system produced a frequency proportional to the amount of column effluent deposited on the SAW sensor. Discrimination between domestic and imported Angelica gigas Nakai was achieved through recognition of visual pattern using $VaporPrint^{TM}$ derived from frequency and chromatogram of GC-SAW sensor.

• Korean Journal of Environmental Biology
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• v.22 no.3
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• pp.394-399
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• 2004

A BOD sensor was prepared with S. marcescens LSY4 and was applied for measurement of BOD values of a solution containing the standard organic pollutants. The sensor sensitivity was nearly independent of the culture time in the range of 9-16 hours. It was also affected little by the cell mass in the range of 0.22-0.75 mg $cm^{-2}$. A cyclic change in the solution pH in the range of 4-9 was accompanied by a reversible variation in the sensor sensitivity. However, the reversibility was lost when the solution pH became more acidic or more basic. Heavy metal ions lowered the sensor sensitivity, which took place more precipitously in the presence of $Cu^{2+}$ and $Ag^+$ rather than in the presence of $Zn^{2+}$ and $Cd^{2+}$. The reduction of the sensor sensitivity was significantly attenuated by loading heavy metal ion tolerance induced strain. The $Cu^{2+}$tolerance induced strain was more efficient for the attenuation than $Zn^{2+}$ and $Cd^{2+}$ tolerance induced strain.

• 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.