• Journal of Sensor Science and Technology
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• v.25 no.5
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• pp.377-381
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• 2016

NDIR $CO_2$ gas sensor was prototyped with ASIC implemented thermopile sensor which included temperature sensor and White-Cell structure in this paper. The temperature dependency of dual infrared sensors ($CO_2$ and reference IR sensors) has been characterized and their output voltage ratios according to the temperature and gas concentration were presented in this paper for achieving temperature compensation algorithm. The initial output voltages of NDIR $CO_2$ gas and reference IR sensors showed $3^{rd}$ order polynomial and linear output voltages according to the variation of ambient temperatures from 253 K to 333 K, respectively. The output voltages of temperature sensor presented a linear dependency according to the ambient temperature and could be described with V(T) = -3.0069+0.0145T(V). The characteristics of output voltage ratios could be modeled with five parameters which are dependent upon the ambient temperatures and gas concentration. The estimated $CO_2$ concentrations showed relatively high error below 300 ppm (maximum 572 % at 7 ppm $CO_2$ concentration), however, as the concentration increased from 500 ppm to 2,000 ppm, the overall estimated errors of $CO_2$ concentrations were less than ${\pm}10%$ in this research.

• KSBB Journal
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• v.7 no.1
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• pp.27-31
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• 1992

Xylose represents a major component of cellulosic materials. This paper describes patterns of ethanol fermentation by Saccharomyces cerevisiae from xylulose, which is an isomer of xylose. Special emphasis was placed on the effects of xylulose concentration and growth temperature on cell growth and ethanol yield. The maximum specific growth of $0.087 1/hr^{-1}$ was obtained at an initial xylulose concentration of 5 g/1. The ethanol yield was propotional to initial xylulose concentrations. A xylulose concentration of 16 g/l resulted in the maximum ethanol yield of 0.49 g EtOH/g xylulose, which corresponds to 90% of a theoretical value. It is interesting to nota that xylulose metabolism was accelerated by the presence of glucose as a carbon source.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.1
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• pp.10-15
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• 2002

Environmental and medium factors were investigated as basic data for optimizing DHA production when using Thraustochytrium aureum. To study the effect of environmental conditions, the rotation speed and culture temperature were changed. Plus the trend of the growth characteristics, lipid content in the biomass, and DHA content in lipids were evaluated according to various initial glucose concentrations. The biomass, lipid, and DHA analyses showed that the physiological characteristics of T. aureum were closely related with the environmental and medium conditions, as in the case of other marine microorganisms. For example, a low rotation speed of 50 rpm lowered the cell growth rate as well as the DHA content in the lipids. A low temperature had a negative effect on the cell growth, yet a positive effect on the lipid content in the biomass. Different initial glucose concentrations had no effect on the lipid content in the biomass or DHA content in the lipids, yet did affect the cell growth. Accordingly, these results show that environmental and medium factors must be synthetically considered in order to optimize DHA production when using T. aureum.

• The Journal of the Korean Society for Microbiology
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• v.20 no.1
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• pp.55-63
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• 1985

Phosphate, ammonia, glucosamine, glucose, pyruvate, succinate, fumarate, malate and acetate were examined for their ability to control the heat-stable enterotoxin (ST) production in succinate salts medium or in M9 medium. The results obtained were summerized as follows. 1. When the initial phosphate concentration was adjusted to 1.0mM, ST production was decreased to 80u/ml or less. But when the initial phosphate concentration was adjusted to 64mM or 100mM, enterotoxin production was 320u/ml. 2. When the initial ammonia concentration in the medium was adjusted to 1.0mM, no ST production and cell growth were observed. But when ammonia concentration was adjusted to 10mM, 19mM, 38mM or 76mM, enterotoxin production was 320u/ml. 3. Among carbon sources, glucosamine, glucose, pyruvate, succinate, fumarate, malate and acetate, acetate supported the highest specific production (928 unit/O.D.) of heat-stable enterotoxin. From this results, we could assume that heat-stable enterotoxin production is controlled by stringent control mechanism. 4. When the pH of the succinate salts medium was kept between 6.2 to 6.5, no heat-stable enterotoxin production was observed, but when the pH of the medium was kept between pH 6.2 to 6.5, 267 unit/O.D. of heat-stable enterotoxin was produced. 5. Glucose inhibited the heat-stable enterotoxin production and the mechanism was assumed due to its capacity to lower the pH of the medium during catabolysis and its high metabolic energy.

• Journal of Environmental Health Sciences
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• v.33 no.4
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• pp.293-298
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• 2007

The microorganism for ammonia gas removal was isolated from composting product. This was identified as Brevundimonas diminuta by morphological, biochemical characteristics study and 16S rDNA sequence analysis. Optimal incubation temperature for cell growth and oxidizing ability of $NH_4-N$ was $30^{\circ}C$ and optimal initial pH was 7. Glucose affected the growth of cell and the removal of $NH4^+$. The growth rate of the isolates were increased when grown in the presence of 0.05-1%(w/v) glucose in the selective medium and lurker increases in glucose concentration to 2% caused significant decreases in the cell growth and oxidizing ability of $NH4^+$.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.731-734
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• 2001

An efficient fermentation strategy for the high level production of ultra-high-molecular weight poly(3-hdyroxybutyrate) (PHB) was developed. Although the cell and PHA concentrations obtained by flask cultures at different initial pH (6.0 or 6.9) were almost same level, the molecular mass of PHB produced were quite different along with the initial pH. When a recombinant Escherichia coli XL1-Blue harboring pJC2 containing the Alcaligenes latus PHB biosynthesis genes was cultivated in flask culture (pH 6.0), the PHB having a very high molecular weight of 22 MDa could be produced while only below 1 MDa at initial pH 6.9. The ultra-high-molecular weight PHB could be synthesized to high concentration of 89.8 g/L resulting in the PHB productivity of 2.07 g/L-h by simple fed-batch culture. In this study, we report that PHB having various molecular mass can be produced by employing metabolically engineered E. coli strains harboring the plasmids of different copy numbers containing the A. latus phbCAB genes.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.229-238
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• 2021

The selective permeate transport characteristics of iodine ion at follicle cell membrane model in thyroid which irradiated by high energy x-ray(linac 6 MV) was investigated. The follicle cell membrane model used in this experiment was a polysulfonated copolymerized membrane of poly(4-vinylpyridine-co-acrylonitrile:VP-AN). The difference of membrane thickness [2 mole AN%(w/w)], fixed carrier concentration[VP-AN%(w/w)], OH- concentration were occurred at difference of I- concentration and quantity of thyroid hormone, respectively. The tensile strength in fixed carrier concentration[VP-AN% (w/w): 0-62 %] of irradiated membrane was found to be decreased about 1.2-1.8 times than non-irradiated membrane. The I- selective permeate initial flux with increase of membrane thickness [2mole AN%(w/w)], fixed carrier concentration[VP-AN%(w/ w)], OH- concentration in irradiated membrane were found to be decreased about 2.1-4.5 times, about 2.2-2.5 times, about 2.1-2.67 times than non-irradiated membrane, respectively. As a result, the quantity of thyroid hormone was decreased at irradiated membrane than non-irradiated membrane. The decrease of thyroid hormone was occurred at hypothyroidism and hyperthyroidism, thyroid cancer, and so on. As the thyroid hormone in cell membrane model were abnormal, cell damages were appeared at cell.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.12
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• pp.769-776
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• 2016

In this study, a numerical simulation of a vanadium redox flow battery was investigated for reactions involving an electrochemical species using comprehensive conservation laws and a kinetic model. For a 3-D geometry of the cell, the distributions of electric potential, vanadium concentration, overpotential, and ohmic loss were calculated. The cell temperature and initial vanadium ion concentration were set as variables. The voltage and electrochemical loss were calculated for each variable. The effects of each variable's impact on the electrochemical performance of a vanadium redox flow battery was numerically analyzed using the calculated overpotential in the electrode and the ohmic loss in the electrolyte phase. The cell temperature increased from $20^{\circ}C$ to $80^{\circ}C$ when the voltage efficiency decreased from 89.34% to 87.29%. The voltage efficiency increased from 88.65% to 89.25% when the vanadium concentration was changed from $1500mol/m^3$ to $3000mol/m^3$.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.110-116
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• 2010

Lactic acid (LA) fermentation by Lactobacillus salivarius ATCC 11741 immobilized on loofa sponge (LS) was evaluated. To increase the surface area of LS for cell immobilization, $H_2O_2$ and chitosan were introduced as surface modifying reagents. Four chitosans of different molecular weights were separately coated on LS. All experiments were conducted in shaking flask mode at 100 rpm rotating speed and $37^{\circ}C$ with 5% $CaCO_3$ as a pH regulating agent. The effects of initial glucose concentration were investigated in the range of 20-100 g/l on LA fermentation by free cells. The results indicate that the maximum concentration of LA was produced with 50 g/l glucose concentration. The immobilized cell system produced 1.5 times higher concentration than free cells for 24 h of fermentation. Moreover, immobilized cells can shorten the fermentation time by 2-fold compared with free cells at the same level of LA concentration. At 1% (w/v) chitosan in 2% (v/v) acetic acid, the Yp/s and productivities of various molecular weights of chitosans were insignificantly different. Repeated batch fermentations showed 5 effective recycles with Yp/s and productivity in the range of 0.55-0.85 and 0.90-1.20 g/l.h, respectively. It is evident that immobilization of L. salivarius onto LS permits reuse of the system under these fermentation conditions. Scanning electron micrographs indicated that there were more intact cells on the chitosan-treated LS than on the untreated LS, thus confirming the effectiveness of the LS-chitosan combination when being utilized as a promising immobilization carrier for LA fermentation.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.272-276
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• 2005

Candida tropicalis, an osmophilic strain isolated from honeycomb, produced xylitol at a maximal volumetric production rate of 3.5 g $l^{-1}$ $h^{-1}$ from an initial xylose concentration of 200 g $l^{-1}$. Even with a very high xylose concentration, e.g., 350 g $l^{-1}$, this strain produced xylitol at a moderate rate of 2.07 g $l^{-1}$ $h^{-1}$. In a fed-batch fermentation of xylose and glucose, 260 g $l^{-1}$ of xylose was added, and xylitol production was 234 g $l^{-1}$ for 48 h, corresponding to a rate of 4.88 g $l^{-1}$ $h^{-1}$. To increase the xylitol production rate, cells were recycled in a submerged membrane bioreactor with suction pressure and air sparging. In cell-recycle fermentation, the average concentration of xylitol produced per recycle round, total fermentation time, volumetric production rate, and product yield for ten rounds were 180 g $l^{-1}$, 195 h, 8.5 g $l^{-1}$ $h^{-1}$, and 85%, respectively. When cell-recycle fermentation was started with the cell mass contratrated two-fold after batch fermentation and was performed for ten recycle rounds, we achieved a very high production rate of 12 g $l^{-1}$ $h^{-1}$. The production rate and total amount of xylitol produced in cell-recycle fermentation were 3.4 and 11 times higher than in batch fermentation, respectively.