• Journal of Microbiology
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• v.34 no.2
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• pp.137-143
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• 1996

We isolated a promoter inducible by paraquat, a superoxide-generating agent, from Escherichia coli using a promoter-probing plasmid pRS415. From sequence analysis we found out the promoter is for fpr ENCODING nadph : ferredoxin oxidoreductase. We constructed on operon fusion of lacZ gene with fpr promoter to monitor the expression of the gene in the single-copy state. LacZ expression generators, menadione and plumbagin, also induced the expression of .betha.-galactosidase in the fusion strain. On the other hand, no significant induction was observed by treatment with hydrogen peroxide, ethanol, and heat shock. Induction of .betha.-galactosidase was significantly reduced by introducing a .DELTA. sox 8 :: cat of soxS3 :: Tn10 mutation into the fusion strain, indicating that fpr gene is a member of the soxRS regulon. The transcriptional start site was determined by primer extension analysis. Possible roles of fpr induction in superoxide stress were discussed.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.688-689
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• 2006

Ni-doped $CoSb_3$ was prepared by the encapsulated induction melting and hot pressing, and its doping effects on the thermoelectric properties were investigated. Single phase $\delta-CoSb_3$ was successfully obtained by the subsequent heat treatment at 773K for 24 hours. Nickel atoms acted as electron donors by substituting cobalt atoms. Thermoelectric properties were remarkably improved by the appropriate doping.

• Journal of Sericultural and Entomological Science
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• no.11
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• pp.63-68
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• 1970

The induction of polyhedroses in the silkworm, Bambyx mari L., was investigated treating the 5th instar larvae just after eodysis with high temperature (hot water bath at 40$^{\circ}C$ for 5 minutes or dry heat shock at 40$^{\circ}C$ for 30 minutes) and low temperature (5$^{\circ}C$ for 24 hours). The results obtained were as follows; 1. Comparing between the frequency of nuclear and cytoplasmic polyhedroses induced by cold and heat treatments (hot water bath at 40$^{\circ}C$ for 5 minutes), the induction ratio of the former is clearly less than that of the latter. But if the larvae tested with cold were left at room temperature (25$^{\circ}C$) for 30-120 minutes till the next hot water bath (40$^{\circ}C$) for 5 minutes and water bath (20$^{\circ}C$) for 5 minutes, treatments, the frequency of induced cytoplasmic polyhedrosis was more than that in the case of cold or hot water bath treatment alone. 2. The frequency of nuclear and cytoplasmic polyhedrosis induced by cold and successive heat (dry heat shock at 40$^{\circ}C$ for 30 minutes), left at room temperature (25$^{\circ}C$) ti11 the second treatment, the frequency of nuclear polyhedrosis was less than that of cytoplasmic polyhedrosis. 3. The reaction of nuclear polyhedra to stains also differs sharply from that of the cytoplasmic type. In a smear of nuclear polyhedra on a slide staining with Giemsa solution remains unstained against a stained back ground, in contrast to this, the cytoplasmic polyhedra take up stain readly.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.3
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• pp.319-332
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• 2010

In general, wastewater treatment systems consume high-energy consumption depending on operation characteristics of the facilities. Therefore, greenhouse gas(GHG) reduction activities that are application of digestion gas, induction of renewable energy etc. are conducted to reduce energy consumption and to increase energy independence ratio. In this study, GHG reduction in wastewater treatment system identified, searched application of Clean Development mechanism(CDM) approved methodology. If the methodologies apply to GHG reduction activities such as application of digestion gas, heat pump system using the wastewater as heat source, hydropower using the methodology determined CDM applicability, otherwise through several assumptions calculated expectable GHG reduction emissions and determined CDM applicability. As a result, the order of calculated GHG reduction emission showed that collected and energy generation of digestion gas is 66,775 $tCO_2$/yr, gas engine cogeneration system is 8,182 $tCO_2$/yr, heat pump system using the wastewater as a heat source is 72,715 $tCO_2$/yr, and hydropower is 561 $tCO_2$/yr. Consequently, the order of calculated Certified Emission Reductions(CERs) benefit showed that heat pump system using the wastewater, as a heat source is 1,381 million won/yr was estimated as the highest, followed by a collected and energy generation of digestion gas is 1,268 million won/yr.

• Korean Journal of Materials Research
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• v.19 no.9
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• pp.457-461
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• 2009

Recently, metal molding has become essential not only for automobile parts, but also mass production, and has greatly influenced production costs as well as the quality of products. Its surface has been treated by carburizing, nitriding and induction hardening, but these existing treatments cause considerable deformation and increase the expense of postprocessing after treatment; furthermore, these treatments cannot be easily applied to parts that requiring the hardening of only a certain section. This is because the treatment cannot heat the material homogeneously, nor can it heat all of it. Laser surface treatment was developed to overcome these disadvantages, and, when the laser beam is irradiated on the surface and laser speed is appropriate, the laser focal position is rapidly heated and the thermal energy of surface penetrates the material after irradiation, finally imbuing it with a new mechanical characteristic by the process of self-quenching. This research estimates the material characteristic after efficient and functional surface treatment using HPDL, which is more efficient than the existing CW Nd:YAG laser heat source. To estimate this, microstructural changes and hardness characteristics of three parts (the surface treatment part, heat affect zone, and parental material) are observed with the change of laser beam speed and surface temperature. Moreover, the depth of the hardened area is observed with the change of the laser beam speed and temperature.

• Journal of Ceramic Processing Research
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• v.22 no.2
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• pp.169-178
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• 2021

In this work, in-flight synthesis route of Ga doped ZnO (GZO) nano-powders was investigated experimentally and numerically, using Radio-Frequency (RF) induction plasmas. For experimental study, mixture of micron-sized ZnO and Ga₂O₃ powders were treated by RF induction plasmas, then, the as-treated powders were retrieved from reactor bottom and filtration for characterization. For numerical study, single particle model was combined with two-dimensional simulation code of RF induction plasma to predict the particle behaviors of ZnO and Ga₂O₃ depending on their sizes. First, experimental results showed that filtration-retrieved powders were characterized as GZO nano-powders although gallium content can be decreased due to Ga₂O₃ decomposition into sub-oxides at the elevated temperatures. From reactor bottom, however, spherical structures consisting of Ga₂O₃ and ZnO particles were observed in sub-millimeter sizes. Numerical results predicted that micron-sized (≤ 10 ㎛) ZnO and Ga₂O₃ particles can vaporize easily during the flight of plasma, while particles with the sizes of 25~100 um were simulated to be partially evaporated or unevaporated. Comparing these experimental and numerical results indicates that GZO nano-powders can be synthesized from vapor species of ZnO and Ga₂O₃, which are primarily produced by in-flight treatment of micron-sized ZnO and Ga₂O₃ powders in RF induction plasmas.

• Journal of Power System Engineering
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• v.15 no.5
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• pp.22-29
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• 2011

In this study, the damage mechanism of large scale steam turbine due to water induction was analyzed and recovery characteristics were reviewed. A turbine consists of the rotating rotor and the stationary casing, and the clearance between them is very small for the efficiency enhancement. If water induction, while relatively cold steam or water is introduced into turbine, occurs, the considerable humping is caused at the casing near the initial water induction point and that induces the rubbing between rotor and casing. Finally, it leads to the catastrophic failure. Bowed rotor has the different characteristics in the recovery depending on damage degree. The elastic deformation due to light rubbing is recovered by turning the rotor with 3 rpm under normal operation condition, but most plastic deformation due to rubbing deforms the local microstructure and that results in permanent deformation which could not be recovered under normal operation condition. Bowed rotor has diverse characteristics depending on the recovery method, and the method is empirical and needs the cutting edge technology. Careful recovery treatment of the rotor will eliminate the risks and secure the high quality rotor similar to new rotor. If any critical error is made during the recovery, the rotor would not be recovered permanently and it should be scrapped.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.2
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• pp.65-69
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• 2017

AlN single crystal was thermally treated at 1600, 1700 and $1800^{\circ}C$ in the ambient pressure of under 100 torr. AlN single crystal was obtained by PVT (Physial Vapor Transport) method using by a facility having a growth part which was heated by RF (Radio Frequency) induction heating. The single crystal specimens surface was evaluated by optical microscope and it was recognized that their morphology was varied with the heat treatment temperature and a set ambient pressure. In this report, the optical microscopic results were reported. According to the increase of temperature the crystal surface was etched thermally. It was evaluated by appearance of small pits on the crystal surface.

• Journal of Aerospace System Engineering
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• v.11 no.3
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• pp.1-7
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• 2017

The applications of high-frequency induction heating has recently been studied in various industrial fields. In this study, induction heating is applied to a SCM440 specimen that is widely used in industry. The specimen was made up of a cylinder 20 mm in diameter and 160 mm long. An induction heating power supply module was used to generate heat in the cylinder at a high frequency (approximately 85 kHz) for 50 seconds. The temperature of the specimen was measured at the 150 mm length in 5 second intervals. Results such as joule heat and temperature are compared with the numerical model analysis using an electromagnetic-thermal co-simulation technique. The analytical model of the cylinder was modeled by considering the skin effect. The median measured temperature after induction heating was conducted for 50 seconds was $57.65^{\circ}C$, compared to a predicted analytical value of $57.27^{\circ}C$. Thus, the analytical results are in good agreement with the experimental results, and this model can predict the induction heating phenomenon numerically.

• Journal of the Korean Society for Heat Treatment
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• v.6 no.2
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• pp.98-106
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• 1993

Ultra high carbon steel (Fe-1.4%C) was prepared by means of a high frequency induction furnace. The preferred nucleation site of martensite was observed. The changes of hardness and impact thoughness due to tempering temperatures, and the spheroidization of cementite by controlled -rolling were also studied for the steel. The preferred nucleation site of martensite in the ultra high carbon steel is prior austenite grain boundary. The hardness of the steel is slightly increased up to about $300^{\circ}C$, and then decreased with further tempering temperature. However, the impact energy keeps a almost constant value, independent of the tempering temperature. The spheroidization of cementite is accelerated as the reduction in thickness per rolling pass is increased and the number of the rolling passes becomes greater.