• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.655-662
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• 2009

In order to obtain knowledge on the design and operation of practical?scale Cylinder-Shaped Filters, pilot experiments were conducted to observe the effects of stepwise augmentation of production rate on water quality and clogging. A production rate increase from 0.8 L/min to 2.4 L/min did not appear to affect the removal efficiencies of BOD(Biochemical Oxygen Demand), SS(Suspended Solids), and turbidity, as the values were maintained around 80%, over 95%, and over 90% respectively;however, COD(Chemical Oxygen Demand) removal decreased from 44% to 29%. In addition, results indicated an inverse relationship between production rate and detention time required to remove unit contaminant concentration, the observed detention time in the filter to remove 1 mg-COD/L being 83 minutes for the production rate of 0.8 L/min and 45 minutes for the production rate of 2.4 L/min, suggesting that a relatively higher production rate is likely to be more advantageous in the purification of reservoir water when compared to a lower production rate. Clogging was observed to originate from the surface and advance to the center of the filter, and although clogging seemed to increase as the production rate increased, this did not cause any difficulties in normal functioning of the filter for more than 2 years of operation, suggesting that this filter system can be used effectively in the purification of reservoir water.

• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.173-177
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• 1989

Cell density was gradually decreased as the dilution rate was increased under chemostat cultivation of HeLa cells. Maxium cell density was maintained at the dilution rate of 0.020 (1/h) which was far less than the wash-out rate of 0.050 (1/h), Maxium cell productivity of 2 (mL of cells/L/h)was obtained at the dilution rate of 0.030 (1/h) by showing the culture also required maintenance period at low dilution rates, whose result meant the deviation of continuous culture theroy. Methods of indirectly measuring cell density have been introduced to represent mammalian cell growth, which are packed cell volume and oxygen uptake rate, and these values showed good linear relationship with actual cell density by having correlation factor of 0.90. Theoretical maximum oxygen yield, $Y_{O2}^{max}$ and maintenance oxygen consumption rate, m$_{O2}$, were estimated as 4.1$\times$10$^5$ (cells/mmole $O_2$) and 10.71$\times$10$^{-9}$ (mmole $O_2$/cells/h) by employing oxygen yield model.

• KSBB Journal
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• v.13 no.5
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• pp.547-553
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• 1998

For the efficient production of a new exo-polysaccharide from Ganoderma lucidum ASI 7004, the optimum conditions and methods in submerged cultivation were investigated with an airlift fermenter system. The optimum aeration rate was 2.5 Wm at the initial pH 5.0 and 28$^{\circ}C$. The increase of dissolved oxygen concentration by pure oxygen supply during cultivation did not improved the exo-polysaccaride production and the mycelial growth. The maximum exo-polysaccharide production and the mycelial growth under the optimum culture condition were obtained in media of glucose 60g/L, yeast extract 6g/L, (NH4)2HPO4 1g/L and KH2PO4 0.5g/L. Under these optimum medium and culture conditions, about 7.15g/L of exo-polysaccharide and 13.9g/L of mycelial growth were producted, respectively.

• Journal of Environmental Science International
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• v.24 no.7
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• pp.947-954
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• 2015

Dielectric barrier discharge plasma is a new technique in water pollutant degradation, which that is characterized by the production of chemically active species such as hydroxyl radicals, ozone, hydrogen peroxide, etc. If dissolving of plasma gas generated in the plasma reaction has increased, it is possible to increase the contaminant removal capacity. In this study, the improvement on the dissolving performance of plasma gas was evaluated by the indirect method measuring the overall oxygen transfer coefficient. Experiments were conducted to examine the effects of nozzle type, distance from water surface, air supply rate and liquid circulation rate. The experimental results showed that the $K_{La}$ value of the 3-prong nozzle is 2.67 times higher than the diffuser. The order of $K_{La}$ value with nozzle type ranked in the following order: 3-prong nozzle (inner diameter, less 1 mm) > circular nozzle (inner diameter, 1.5 mm) > ellipse nozzle (short diameter 1 mm, long diameter 2.5 mm) > circular nozzle (inner diameter, 3 mm). Optimal liquid circulation rate was appeared to be 1.7 L/min, the value of $K_{La}$ was 0.510 1/min. The value of $K_{La}$ with increasing air supply rate was revealed in the form of an exponential such as $K_{La}=0.3581e^{0.2919^*air\;flow\;rate}$.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.64-68
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• 2005

Methane reforming processes to obtain hydrogen were investigated experimentally by using atmospheric plasma source. Among possible reforming processes, such as a $CO_2$ reforming(dry reforming), a partial oxidation (POx), a steam reforming(SR), and a steam reforming with oxygen(SRO or auto-thermal reforming), partial oxidation and the steam reforming with oxygen were considered. We choose a rotating arc plasma as an atmospheric plasma source, since it shows the best performances in our preliminary tests in terms of a methane conversion, a hydrogen production, and a power consumption. Then, the effects of a feeding flow-rate, an electrical power input to a plasma reaction, an $O_2/C$ ratio and a steam to carbon ratio in the case of SRO on the reforming characteristics were observed systematically. As results, at a certain condition almost 100% of methane conversion was obtained and we could achieve the same hydrogen production rate by consuming a half of electrical power which was used by the best results for other researchers.

• Microbiology and Biotechnology Letters
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• v.7 no.4
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• pp.211-216
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• 1979

Air lift fermentor (ALF) is widely used for production of single-cell protein (SCP) from hydrocarbon and other carbon sources, because oxygen transfer efficiency is believed to be superior in the ALF to that in other conventional fermentors. However, the performance of ALF in terms of mixing is somewhat questionable. In this research, we studied about the performance of the ALF in SCP production using methanol fermentation process as a model system. The results show that ALF could be employed for SCP production or other fermentation processes when substrate is miscible and used at low concentration. With a high substrate concentration, it must be operated under high pressure or low dilution rate to meet the adequate oxygen transfer requirement.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.283-286
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• 2000

The effects of dissolved oxygen and pH on the cell growth and mass production of high-molecular weight pullulan by A. pullulans ATCC 42023 were evaluated. For the production of commercially useful pullulan with high-molecular weight, the influence of pH control on the pullulan production and growth of A. pullulans was studied in batch fermentation. It was found that the productivity of high-molecular weight pullulan with pH control at 6.5 was higher than that with no pH control. The influence of dissolved oxygen on the pullulan production and growth was studied. It was found that pullulan yield and synthesis rate increased with oxygen availability.

• Ocean Science Journal
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• v.43 no.1
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• pp.39-48
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• 2008

Tritium ($^3H$ or T) has been produced mostly by atmospheric nuclear weapon tests, and entered the ocean in the form of water (HTO). As tritium exists as water itself, it has been regarded as an ideal tool to study the transport of water masses. In April 2001 we collected water samples in the western Japan Basin (WJB) for tritium and helium measurement. The timely sampling provided direct evidence of the bottom water formation, resulting in the drastic increase in tritium concentration from 0.3 TU in 2000 to 0.67 TU in 2001. Considering that the new bottom waters were found mostly in the WJB, it implies that maximum 1% of the whole bottom layer below 2600 m should be replaced with the surface water during the severely cold winter 2000 2001. $^3H-^3He$ age, showing the elapsed time since the water left from the surface, can be used to calculate oxygen utilization rate by dividing AOU by the age. Under the condition of 90% oxygen saturation in the surface water, the integration of OUR in the water column below 200 m yields net oxygen consumption of 12 mol $(O_2)m^{-2}yr^{-1}$, which corresponds to the export production of $99\;g\;C\;m^{-2}yr^{-1}$. This estimate is comparable to a previous estimate based on satellite data and implies that the ratio of export to primary production(f-ratio) is as high as 0.5 in the WJB.

• Carbon letters
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• v.14 no.4
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• pp.247-250
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• 2013

In this study, we present a facile method of fabricating graphene oxide (GO) films on the surface of polyimide (PI) via layer-by-layer (LBL) assembly of charged GO. The positively charged amino-phenyl functionalized GO (APGO) is alternatively complexed with the negatively charged GO through an electrostatic LBL assembly process. Furthermore, we investigated the water vapor transmission rate and oxygen transmission rate of the prepared (reduced GO $[rGO]/rAPGO)_{10}$ deposited PI film (rGO/rAPGO/PI) and pure PI film. The water vapor transmission rate of the GO and APGO-coated PI composite film was increased due to the intrinsically hydrophilic property of the charged composite films. However, the oxygen transmission rate was decreased from 220 to 78 $cm^3/m^2{\cdot}day{\cdot}atm$, due to the barrier effect of the graphene films on the PI surface. Since the proposed method allows for large-scale production of graphene films, it is considered to have potential for utilization in various applications.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.5
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• pp.753-758
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• 2016

Moisture content influences physiological characteristics of microbes and physical structure of solid matrices during composting of animal manure. If moisture content is maintained at a proper level, aerobic microorganisms show more active oxygen consumption during composting due to increased microbial activity. In this study, optimum moisture levels for composting of two bedding materials (sawdust, rice hull) and two different mixtures of bedding and beef manure (BS, Beef cattle manure+sawdust; BR, Beef cattle manure+rice hull) were determined based on oxygen uptake rate measured by a pressure sensor method. A broad range of oxygen uptake rates (0.3 to 33.3 mg $O_2/g$ VS d) were monitored as a function of moisture level and composting feedstock type. The maximum oxygen consumption of each material was observed near the saturated condition, which ranged from 75% to 98% of water holding capacity. The optimum moisture content of BS and BR were 70% and 57% on a wet basis, respectively. Although BS's optimum moisture content was near saturated state, its free air space kept a favorable level (above 30%) for aerobic composting due to the sawdust's coarse particle size and bulking effect.