• 한국자동차공학회논문집
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• 제4권3호
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• pp.176-186
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• 1996

The phenomena of drag reduction using small quantities of a liner macromolecules has attracted the attention of many experimental investigations. On the other hand drag reduction in two phase flow can be applied to the transport of crude oil, phase change system such as chemical reactor, pool and boiling flow, and to flow with cavitation which occurs pump impellers. But the research on dragreduction in two phase flow is not sufficient. The purpose of the present work is to evaluate the drag reduction by measuring pressure drop, void fraction, mean liquid velocity and turbulent intensity whether polymer additives a horizontal single and two phase system or not. Flow pattern of air-water two phase flow was classified by electrical conductivity probe signal. Velocities and turbulent intensities of signal were measured simultaneously with a Hot-film anemometer.

• 환경생물
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• 제36권2호
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• pp.199-205
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• 2018

Petroleum energy is the major source of the world energy market, and its massive usage, and the corresponding extreme environmental pollution, imposes a serious threat on the ecological cycles. By screening oil-contaminated soil, we isolated, identified, and characterized a novel strain that represents a considerable diesel-degrading potentiality; the Bacillus aryabhattai DA2 strain is registered in the NCBI with the accession number MG571630, and it possesses an efficient tributyrin-degrading capacity. The optimal condition for diesel degradation by DA2 strain was observed at pH between 7-8 and at the temperature of $30^{\circ}C$. The strain is resistant to salt as well as the antibiotics like ampicillin and streptomycin. These results indicate B. aryabhattai is one of the potential candidates for the remediation of the diesel-contaminated sites.

• 한국식물학회:학술대회논문집
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• 한국식물학회 1985년도 워크샵 및 심포지엄 북한산국립공원의 식생
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• pp.83-96
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• 1985

cDNAs for long- and short-chain acyl-CoA oxidases in fatty acid $\beta$-oxidation were isolated and were characterized their enzymatical and molecular properties. Both oxidases were exclusively localized in glyoxysomes, indicating that glyoxysomes can completely metabolize fatty acids to acyl-CoA by their cooperative action. In order to clarify the regulatory mechanisms underlying degradation of storage oil, we tried to obtain glyoxysome-deficient mutants of Arabidopsis. We screened 2,4-dichlorophenoxybutyric acid (2,4-DB) mutants of Arabidopsis which have defects in glyoxysomal fatty acid $\beta$-oxidation. Four mutants can be classified as carrying alleles at three independent loci, which we designated pedl, ped2, and ped3, respectively (where ped stands for peroxisome defective). The characteristics of these ped mutants are described.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 전기설비
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• pp.73-75
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• 2005

In present measurement of moisture contents is used as one of method for estimating degradation of transformer. Most of people use Karl-Fischer titration method for detection moisture contents but this measurement is inconvenient method because we must analyze transformer oil-paper after dismounting transformer and sampling in field. Therefore we don't directly investigate them in field. In this paper we will introduce Recovery Voltage Method(RVM) that is new method for estimating measurement in field though dismounting facility. For measure of moisture contents using RVM in accordance with accelerated thermal aging we have made experimental test cell and aged at a temperature up to 140$^{\circ}C$ for 300 hours. And we have been measured at intervals of 100 hours using RVM 5462 made in fetter company.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 전기설비
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• pp.79-81
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• 2005

Chemical methods for moisture contents detection of insulation system in transformer must dismount equipment for sampling, and there is shortcoming such as acquiring partial data for measuring. Also the samples can't immediately analyze in field. The Recovery Voltage Method (RVM) will be able to measure a moisture contents at low voltage without dismounting equipment. Therefore, in advanced countries RVM would be used to measure the moisture contents which permeates to the insulation system without weighting additive degradation or mechanical damage. In this paper we have investigated for overcoming these shortcomings using the RVM, and we have measured the moisture contents of transformer insulation with temperature.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2003년도 제40회 국제학술심포지움
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• pp.101-101
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• 2003

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.428-431
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• 1997

In order to compare with domestic underground distribution cables, the foreign cable which was manufactured in USA, 1982 and has been serviced in field for 13 years was characterized with several tests. Water trees, voids, and convolutions are not found in insulation. In hot oil test, insulation is very clean and there was no separation of insulation and conductor shield. The results of degree of crosslinking, FTIR, and DSC are also usual. Specially, the distribution of OIT is very good, which is different from that of domestic cables. The content of impurities is relatively small. This cables was manufactured with good state and no extraordinary degradation is found.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1486-1487
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• 2006

본 논문은 변압기의 과부하 상태를 모의하고 내부 절연물의 잔존수명을 평가하기 위한 방법으로 가속 열 열화 시험을 수행하였으며, 광유 함침 절연지의 열 스트레스에 의한 절연 열화 특성을 분석하였다. 시험에 사용된 절연재료는 변압기의 주 절연물로 널리 사용하고 있는 셀룰로스계 크래프트 절연지와 광유계 절연유를 사용하였다. 가속 열 열화 시험은 IEEE/ANSI Standard C59.91-1981의 수명 예측 곡선에 의거하여 국내 배전환경에 부합하도록 $55^{\circ}C$ 절연시스템을 기준으로 하였으며, $150^{\circ}C$에서 약 1,000시간 동안 열 스트레스를 인가함으로써 변압기의 수명이 다하도록 모의하였다. 또한 절연지의 절연 열화 특성을 분석하기 위해 인장강도, 비유전율, 절연파괴 강도를 시험하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.449-452
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• 2004

The life of power transformer is basically dependent on the aging deterioration of insulating paper. Analysis of insulating paper for its DP value or tensile strength requires removal of a few strips of paper but direct measurement of this properties is not practical for in-service transformers. For this reason furfural analysis by HPLC has gained increasing favor as a means of estimating degradation of insulating papers in power transformers and this paper reports on the analysis of data on the concentration of furfural in oil samples from about 50 power transformers and the case study. The data showed that furfural content can estimate more accurately aging characteristics compared to concentration of CO, $CO_2$. We expect that these results can be useful to predict the aging characteristics and life diagnosis of power transformers and further the study must be continued.

• 자원리싸이클링
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• 제6권2호
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• pp.12-21
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• 1997

Plastics waste constitutes approximately 23% by volume of the municipal solid waste(MSW) generated in the U.S. each year, and have slow rate of degradation in the environment. Therefore, there is a great deal of public pressure to recycle plastics, and more than 100 million people participate in the curbside recycling programs. Despite the high level of public interest, only 3.5% of the plastic are recycled, which is substantially lower than the recycle rates of other materials such as paper fibers, glass, and iron. Although a large part of the reason is due to the low price of virgin polymers, which in turn is due to the low price of oil, it is possible to make the plastics recycling as a profitable business by developing advanced technologies. In this communication, various methods of separating pplastics from metals and from each other are discussed.