• Environmental Engineering Research
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• v.20 no.1
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• pp.51-57
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• 2015

As expected, the expression of denitrifying genes in a Typha wetland (relatively stagnant compared to other ponds), showing higher nitrogen removal efficiency in summer, was affected by temperature. The abundance and gene transcripts of nitrate reductase (narG), nitrite reductase (nirS), nitric oxide reductase (norB), and nitrous oxide reductase (nosZ) genes in seasonal sediment samples taken from the Acorus and Typha ponds of free surface flow constructed wetlands were investigated using quantitative polymerase chain reaction (Q-PCR) and quantitative reverse transcription PCR (Q-RT-PCR). Denitrifying gene copy numbers ($10^5-10^8$ genes $g^{-1}$ sediment) were found to be higher than transcript numbers-($10^3-10^7$ transcripts $g^{-1}$ sediment) of the Acorus and Typha ponds, in both seasons. Transcript numbers of the four functional genes were significantly higher for Typha sediments, in the warm than in the cold season, potentially indicating greater bacterial activity, during the relatively warm season than the cold season. In contrast, copy numbers and expression of denitrifying genes of Acorus did not provide a strong correlation between the different seasons.

• Environmental Engineering Research
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• v.19 no.4
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• pp.387-393
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• 2014

The purpose of this study is to evaluate integrated anaerobic hydrogen fermentation and membrane bioreactor (MBR) for on-site domestic wastewater treatment and resource recovery. A synthetic wastewater (COD 17,000 mg/L) was used as artificial brown water which will be discharged from urine diversion toilet and fed into a continuous stirred tank reactor (CSTR) type anaerobic reactor with inclined plate. The effluent of anaerobic reactor mixed with real household grey water (COD 700 mg/L) was further treated by MBR for reuse. An optimum condition maintained in anaerobic reactor was HRT of 8 hrs, pH 5.5, SRT of 5 days and temperature of $37^{\circ}C$. COD removal of 98% was achieved from the overall system. Total gas production rate and hydrogen content was 4.6 L/day and 52.4% respectively. COD mass balance described the COD distribution in the system via reactor byproducts and effluent COD concentration. The results of this study asserts that, anaerobic hydrogen fermentation combined with MBR is a potent system in stabilizing waste strength and clean hydrogen recovery which could be implemented for onsite domestic wastewater treatment and reuse.

• Journal of ILASS-Korea
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• v.8 no.3
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• pp.41-48
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• 2003

This work was performed to investigate the distribution of the fuel droplet size around the bluff-body and the combustion characteristics. The bluff-body is used fur the purpose of increasing the combustion efficiency by stabilizing the flame. Diameters of the bluff-body in this experiment are 6, 8, and 10mm and the impingement angles are $30^{\circ},\;60^{\circ}\;and\;90^{\circ}$. The measurement points were at the distances of 20 and 30 mm axially from the nozzle. The geometry of the bluff-body influenced the spray shape and the combustion characteristics. The SMD was acquired by image processing technique (PMAS), and the mean temperatures were measured by thermocouple. In the condition of ${\theta}=60^{\circ}$, the values of SMD are not greatly varied compared to the other conditions. As the angle of bluff-body was increased, the high temperature region was wider along radial direction. When the air-fuel ratio was larger than 5.2, the NOx concentration was decreased, and an increase in the diameter of the bluff-body decreased the NOx of emission.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.514-519
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• 2001

Converter has been slag produced 10 million tons per year in Japan. It is a steel making by product produced in the same way as the blast-furnace slag. Though blast-furnace slag is being used effectively as a concrete admixture, the converter stag has never been used effectively because of the expansion action of contained free lime and iron oxide. This is an important environmental problem in the steel industry. Beta-2CaOSiO$_2$(beta-C$_2$S) is contained 40 percent in converter slag, therefore it is very promising as a concrete admixture. We proposed an accelerated aging processes capable of stabilizing the converter slag in a short time. The converter slag is dipped into alkali aqueous solution after heating at low temperature. It was subsequently ground to a grain size of 75 ${\mu}{\textrm}{m}$ , inner 30 percent of OPC. The properties of mortar and concrete using the blended cement were determined. As a result, it has become apparent that the expansion was reduced and long term compressive strength was increased while that at early ages was not so remarkable. The hydration exotherm rate was lower than that of the OPC.

• Journal of environmental and Sanitary engineering
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• v.23 no.1
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• pp.25-31
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• 2008

A bacterial strain, Bacillus megaterium L-49 has been isolated and identified that produces alkaline ${\alpha}$-amylase. The cell is ellipsoidal, about $1.0-1.2{\times}3.0-3.6{\mu}m$ in diameter, Gram-positive, motile, and central partial central. Growth occurs in media containing 7% of NaCl. This strain could utilize D-glucose, lactose, xylose, sucrose, mannose, and maltose, and but it does not utilize D-fructose, and glycogen. Among the various concentrations of saturated ammonium sulfate, the retractation ratio in range of 70 to 100% was about 93%. However, in the case of acetone, it was about 98.7%. EDTA has activating effect and Ca2+ has no effect on alkaline ${\alpha}$-amylase activity. The alkaline ${\alpha}$-amylase has low thermal stability. The optimal temperature for reaction is $50^{\circ}C$. The alkaline ${\alpha}$-amylase activity maintained stabilizing at pH 6-11 and the optimal pH for reaction was 9-10.

• Journal of Powder Materials
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• v.15 no.6
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• pp.450-457
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• 2008

The objectives of this study were the development of a synthesis technique for highly active nanosized ITO powder and the understanding of the reaction mechanisms of the ITO precursors. The precipitation and agglomeration phenomena in ITO and $In_{2}O_{3}$ precursors are very sensitive to reaction temperature, pH, and coexisting ion species. Excessive $Cl^-$ ion and $Sn^{+4}$ ions had a negative effect an synthesizing highly active powders. However, with a relevant stabilizing treatment the shape and size of ITO and $In_{2}O_{3}$ precursors could be controlled and high density sintered products of ITO were obtained. By applying the reprecipitation process (or stabilization technique), highly active ITO and $In_{2}O_{3}$ powders were synthesized. Sintering these powders at $1500^{\circ}C$ for 5 hours produced 97% dense ITO bodies.

• Environmental Engineering Research
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• v.17 no.2
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• pp.111-116
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• 2012

This study investigates the complete removal of nitrate and the recovery of valuable ammonium salt by the combination of nanoscale zero-valent iron (NZVI) and a membrane contactor system. The NZVI used for the experiments was prepared by chemical reduction without a stabilizing agent. The main end-product of nitrate reduction by NZVI was ammonia, and the solution pH was stably maintained around 10.5. Effective removal of ammonia was possible with the polytetrafluoroethylene membrane contactor system in all tested conditions. Among the various operation parameters including influent pH, concentration, temperature, and contact time, contact time and solution pH showed significant effects on the ammonia removal mechanism. Also, the osmotic distillation phenomena that deteriorate the mass transfer efficiency could be minimized by pre-heating the influent wastewater. The ammonia removal rate could be maximized by optimizing operation conditions and changing the membrane configuration. The combination of NZVI and the membrane contactor system could be a solution for nitrate removal and the recovery of valuable products.

• Microbiology and Biotechnology Letters
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• v.13 no.4
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• pp.383-389
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• 1985

Optimum conditions of PEG treatment for the intergeneric fusion of yeast protoplasts were investigated. Fusants were selected by nutritional complementation on minimal medium. The intergeneric fusion frequency between pro-toplasts of S. cerevisiae and C. tropicalis was distributed 10$^{-4}$ to 10$^{-6}$, depending on the combination of parental strains. PEG 4000 or 6000 are equally effective. 30%(w/v) PEG 4000 was found to be optimum and below 20% its stabilizing effect was lost, resulting in protoplast lysis, and optimum pH was 8.0. The efficiency of PEG was enhanced by higher temperature of the PEG solution, and by the addition of Ca ions. The stimulating effect of Ca ions in the range of 1 mM to 100 mM proved similar.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1119-1124
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• 2014

High temperature superconducting magnetic energy storage (HTS SMES) is known as an effective solution to significantly decrease the voltage and power fluctuations of grid connected wind power generation system (WPGS). This paper implements an effective control scheme of a back-toback converter with shunt-connected HTS SMES for the frequency regulation of an islanded microgrid. The back-to-back converter is used to connect the WPGS to the grid. A large-scale HTS SMES is linked to the DC side of the back-to-back converter through a two-quadrant DC/DC chopper. An adaptive control strategy is implemented for the back-to-back converter and the two-quadrant DC/DC chopper to improve the efficiency of the whole system. The performance of the proposed control system was evaluated in a test power system using PSCAD/EMTDC. The simulation results clearly show that the back-to-back converter with shunt-connected HTS SMES operates effectively with the proposed control strategy for stabilizing the power system frequency fluctuations.

• Archives of Pharmacal Research
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• v.15 no.2
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• pp.176-183
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• 1992

The stabilizing effects of $\alpha$-$\beta$-$\gamma$- and dimethyl-$\beta$-cyclodextrins $(\alpha$-, $\beta$-, $\gamma$- and DM-$\beta-$-CyDs) on the degradation of hydrocortisone 17-butyrate (HC-17B) in aqueous solution was investigated. Hc-17B underwent a facile hydroxide ion-catalyzed rearrangement to the less active 21-butyrate ester by the apparent first-order kinetics, and maximum stability of HC-17B was obtained at around pH 4.0. The stability of HC-17B was increased by inclusion complexation with $\alpha$-, $\gamma$- and DM-$\beta$-CyD in the pH range of 2.0-8.0 examined, whereas $\beta$-CyD accelerated the degradation of HC-17B at the pH higher than 5.0. The effects of ionic strength, solvent, temperature and CyD concentration were also investigated. Stability constants and apparent degradation rate constants of HC-17B-$\gamma$-CyD and HC-17B-DM-$\beta$-CyD complexes were determined kinetically on the basis of 1:1 complexation. The results suggested that the inclusion complexation with $\gamma$-CyD or DM-$\beta$-CyD was most useful means to enhance the stability of the steroid.