• Journal of Advanced Marine Engineering and Technology
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• v.28 no.8
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• pp.1203-1210
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• 2004

It was reported recently that the pump head degradation near the best efficiency point from single-phase flow to the break-down due to air entrainment became less in a screw-type centrifugal pump than in a general centrifugal pump. In this paper, I carried out internal pressure measurements and visualizations, and investigated the various physical phenomena occurring inside a screw-type centrifugal pump operated in air-water two-phase flow. The results could give some characteristics about the degradation of pump performance on air-water two-phase flow.

• Journal of Industrial Technology
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• v.29 no.A
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• pp.89-94
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• 2009

The efficiency of heterogeneous catalysts has been investigated in ozonation process for organic removal. Heterogeneous catalytic ozonation was conducted for the degradation of humic acid in the presence of Granular Activated Carbon or Zeolite as a solid catalyst. And the results were compared to those of ozonation alone and adsorption alone without ozonation. The degradation characteristics of humic acid in each process were examined with the values of pH, TOC, $UV_{254}$ and $COD_{Cr}$.

• Journal of Soil and Groundwater Environment
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• v.21 no.1
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• pp.72-79
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• 2016

Bioremediation is one of the most effective ways to remediate TPH-contaminated sites. However, under actual field conditions that are not at the optimum temperature, degradation of microorganisms is generally reduced, which is why the efficiency of biodegradation is known to be significantly affected by the soil temperature. Therefore, in this study, the labscale experiment was conducted using indigenous crude oil degrading microorganisms isolated from crude oil contaminated site to evaluate the remediation efficiency. Crude oil degrading microorganisms were isolated from crude oil contaminated soil and temperature, which is a significant factor affecting the remediation efficiency of land farming, was adjusted to evaluate the microbial crude oil degrading ability, degradation time, and remediation efficiency. In order to assess the field applicability, the remediation efficiency was evaluated using crude oil contaminated soil (average TPH concentration of 10,000 mg/kg or more) from the OO premises. Followed by the application of microorganisms at 30℃, the bioremediation process reduced its initial TPH concentration of 10,812 mg/kg down to 1,890 mg/kg in 56 days, which was about an 83% remediation efficiency. By analyzing the correlation among the total number of cells, the number of effective cells, and TPH concentration, it was found that the number of effective microorganisms drastically increased during the period from 10 to 20 days while there was a sharp decrease in TPH concentration. Therefore, we confirmed the applicability of land farming with isolated microorganisms consortium to crude oil contaminated site, which is also expected to be applicable to bioremediation of other recalcitrant materials.

• Journal of Power System Engineering
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• v.20 no.1
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• pp.42-49
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• 2016

This study showed that on-site ferrate(VI) solution was synthesized by wet oxidation method and applied aqueous 2,4-dichlorophenol(DCP) solution to evaluate the degradation efficiency. On-site ferrate(VI) solution was synthesized by putting $FeCl_3{\cdot}6H_2O$ in the strong alkali solution with NaClO and NaOH and applied DCP solution directly. DCP solution was extracted by the liquid-liquid method and analyzed by GC-ECD. The factors such as pH, DCP initial concentration, injected ferrate(VI) dosage, temperature were investigated. The optimum pH and temperature conditions of DCP degradation were obtained in neutral condition and $35^{\circ}C$. And the experimental results showed that DCP removal efficiency also increased with the decrease of DCP initial condition and the injected ferrate(VI) dosage.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.3
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• pp.269-276
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• 2001

The objective of this study was to investigate the biodegradation of ethylene in an biofilter inoculated with ethylene-oxidizing microorganisms. The biofilter performance was monitored in terms of ethylene removal efficiency and carbon dioxide production. The biofilter was capable of achieving the ethylene removal efficiency as much as 100% at a residence time of 14 min and an inlet concentration of 290 ppm. Under the same conditions, carbon dioxide with a concentration of up to 546 ppm was produced. It was found that carbon dioxide was produced at a rate of 87 mg/day, which corresponded to a volume of 0.05 L/day. Observable features of the ethylene-oxidizing microorganisms, meaning microbial activity occurrence in the biofilter, were investigated with the microscopy analysis.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.3
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• pp.119-123
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• 2013

Most of the world's solar cells in photovoltaic industry are currently fabricated using crystalline silicon. Czochralski-grown silicon crystals are more expensive than multicrystalline silicon crystals. The future of solar-grade Czochralski-grown silicon crystals crucially depends on whether it is usable for the mass-production of high-efficiency solar cells or not. It is generally believed that the main obstacle for making solar-grade Czochralski-grown silicon crystals a perfect high-efficiency solar cell material is presently light-induced degradation problem. In this work, the substitution of boron with gallium in p-type silicon single crystal is studied as an alternative to reduce the extent of lifetime degradation. The diamond-wire sawing technology is employed to slice the silicon ingot. In this paper, the quality of the diamond wire-sawn gallium-doped silicon wafers is studied from the chemical, electrical and structural points of view. It is found that the characteristic of gallium-doped silicon wafers including texturing behavior and surface metallic impurities are same as that of conventional boron-doped Czochralski crystals.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.620-626
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• 1988

GaAs solar cells may be the most attractive and efficient power source of a satellite. GaAs is more radiation tolerant and less temperature sensitive than widely used silicon. $Al_{x}$ Ga$_{1-x}$ As/GaAs solar cells have been designed and fabricated by Liquid Phase Epitaxial method. GaAs solar cells, of which structure is about 0.2 .mu.m p$^{+}$ - window layer, 0.6-1.O .mu.m Ge-doped p-layer. 3.mu.m n-GaAs layer and n$^{+}$ - buffer layer, have been characterized as a function of operating temperature from 25 .deg.C to 130 .deg.C. Open circuit voltage decreases linearly with increasing temperature by 1.4-1.51 mV/ .deg.C while degradation of silicon solar cells is about 2.2-2.5 mV/ .deg.C, short circuit current does not increase much with increasing temperature. Relative efficiency decreases with increasing of temperature by about 0.21-0.29 %/ .deg.C. Efficiency degradation of silicon solar cells with temperature is known to be about 0.5%/ .deg.C and our results show GaAs solar cells may be an excellent candidate for concentrated solar cells.ells.

• KSBB Journal
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• v.25 no.1
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• pp.33-40
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• 2010

Conventional disinfectants and disinfection method are expensive, hazardous and often require long periods of exposure. Recently, there is growing interest in complex disinfection process as a disinfection technique in medical instruments such as endoscope, hand piece bur to improve the disinfection efficiency and conveniency. The aim of this study was to evaluate the performance of a new complex process for the purpose of disinfection of Escherichia coli in water. Three single process (electrolysis, UV and ultrasonic process) was combined dual and triple disinfection process. The order of disinfection performance for E. coli in dual process lie in: Electrolysis + UV > Electrolysis + Ultrasonic > UV + Ultrasonic process. Disinfection efficiency of E. coli and degradation of N, N-Dimethyl-4-nitrosoaniline (RNO, indicating material of OH radical formation) of dual process was higher than that of the triple process (Electrolysis + UV + Ultrasonic process). In electrolysis + UV process, disinfection tendency was well agreed with RNO degradation tendency.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.159-162
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• 2005

In this study, a two-liquid-phase (TLP) bioreactor was conducted to enhance the biodegradation efficiency and rate of PAH. Phenanthrene was degraded efficiently irrespective of the type and the amount of water-immiscible liquid (WIL). The degradation efficiency of anthracene was much higher in paraffine oil than in silicone oil because the mass transfer of anthracene was different in the two WILs. Pyrene was only transferred from soil to WIL during 5 days. It seemed that the degradation of PAH in the TLP bioreactor was mainly dependent on the mass transfer of PAH.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.2
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• pp.140-147
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• 1999

A gene expressing organophosphorus acid (OPA) anhydrolases have been cloned from Alteromonas haloplanktis strain and expressed in bacterial strain BL21. Crude extract was prepared from the transformed bacterial strain BL2l and used in testing its degrading capability of real nerve gas, soman and sarin. Within 1 minute after the start of the reaction, nearly 65% of the soman added to the reactant(3mM) was degraded by adding 1 mg of the crude extract enzyme(20.0 Unit $mg^-{1}$ crude protein). In 6 minutes, the reaction reached at its steady state, which indicates that soman was completely degraded by that time. In the case of sarin, the degradation efficiency was observed to be about 0.7 times of that of soman. If the specific activity of OPAA is enhanced by both increased expression efficiency and purification, OPAA seems to be applied for the development of decontaminant of skin, especially of eye.