• 산업기술연구
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• 제30권B호
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• pp.69-74
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• 2010

Chitinolytic activity was enhanced by coexpression of endo-chitinase gene (chiA) and chitobiosidase gene (chiB) from Serratia marcescens KFRI314 using constitutive expression vector, pHCEIA, in E. coli. Coexpression vector was constructed by inserting ribosome binding site (RBS) into junction between two chitinase genes. SDS-PAGE analyses showed that two chitinase were constitutively expressed while E. coli clones expressing two chitinases simultaneously increased halo size on colloidal chitin plate. Furthermore, the chitinolytic activities were much enhanced in coexpressed clones when degradation patterns of substrate analogues such as 4-MU-(NAG), $4-MU-(NAG)_2$,$4-MU-(NAG)_3$ were used. Consequently, the combined use of endochitinase and chitobiosidase greatly increased overall chitinolytic activities on recombinant E. coli clones.

• Journal of Applied Biological Chemistry
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• 제42권2호
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• pp.57-61
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• 1999

Seven numerically dominant 2-methyl-4-chlorophenoxyacetic acid (MCPA)-degrading bacteria were isolated from agricultural soils. The isolates utilized the herbicide MCPA as a sole carbon source, producing significant biomass in MCPA mineral medium. They exhibited diverse herbicide degradation capabilities, but most of them grew very slowly in mineral medium containing herbicide. The chromosomal DNA patterns of the isolates obtained by polymerase chain reaction amplification of repetitive extragenic palindromic sequences were distinct from each other. One isolate, SH3, which was identified as Sphingomonas species by fatty acid methyl ester analysis, was able to degrade 5 different phenoxyacetic acid herbicides within 4 days. This strain contains two plasmids, and the smaller one has a crucial role in herbicide degradation. MCPA treated into agricultural soils without indigenous MCPA-degraders persisted for a long time, but the application of the isolate SH3 resulted in rapid decline of MCPA concentration in the soil.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2060-2062
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• 1999

When the high voltage is applied on insulation materials that have voids and impurities inner one, then probability of electrical tree inception is increased at defects. Electrical tree gives a profit to degradation analysis, because it is possible to observe by eyes and provides electrical degradation step. And electrical tree is divided to three types in usual - tree type, bush type and chestnut type tree. But these three types are divided not by method of quantitative analysis but visual and experiential analysis. In this paper, three types of electrical tree were calculated by quantitative analysis using fractal mathematics and classified to fractal dimensions (FD). FD of tree types are 1.1$\sim$1.4, bush types are 1.4$\sim$1.6 and chestnut type trees have above 1.6 FD.

• 제어로봇시스템학회논문지
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• 제12권12호
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• pp.1231-1234
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• 2006

In this study, we detected electromagnetic waves generated in an enclosed switchgear and applied various statistical methods for detecting signals. We calculated the various statistical factors via the appropriate statistical methods. Further, we used these statistics to recognize the characteristics for each pattern by identifying the partial discharge in each case for normal, proceeding and abnormal states. The characteristics of electromagnetic wave patterns occurred in various states at electric power facilities and were used as an output variable for more efficient diagnosis. In this paper, we confirmed that the pattern of partial discharge signal can be used as one of the factors used to analyze the insulation state and to consider while estimating diagnosis of insulation states by recognizing the signal pattern to intelligence. We will utilize the proposed diagnosis method to determine insulation degradation states.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마
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• pp.18-22
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• 2000

The partial discharge testing is widely used in insulation property measurement because it gives low stress to high voltage equipment which is undertaken tests. Therefore it is very useful method compare to previous destructive methods and effective diagnosis method in power transformer that requires live-line diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In recent, the study of partial discharge is carrying out discover of initial defect of power equipment through condition diagnosis and system development of degradation diagnosis using HFPD(High Frequency Partial Discharge) detection. In this study, simulated transformer is manufactured and HFPD occurred from transformer is measured with broad band antenna in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마
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• pp.29-32
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• 2000

The partial discharge testing is widely used in insulation property measurement because it gives low stress to high voltage equipment which is undertaken tests. Therefore it is very useful method compare to previous destructive methods and effective diagnosis method in power transformer that requires on-line & on-site diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In recent, the study of partial discharge is carrying out discover of initial defect of power equipment through condition diagnosis and system development of degradation diagnosis using HFPD(High Frequency Partial Discharge) detection. In this study, simulated transformer is manufactured and PD/HFPD occurred from transformer is measured with broad band antenna in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1657-1662
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• 2018

A null test method which relies on a computer generated hologram (CGH) is widely used to measure a large aspheric surface. For precise measurements of the surface shape of an aspheric optics, the CGH must precisely generate a wavefront that can fit on the ideal surface shape of the aspheric optics. If fabrication errors arise in the CGH, an unwanted wavefront will be generated and the measuring result will lack trustworthiness. Thus far, there has been limited research on wavefronts generated by CGH using only linear-type binary grating models. In this study, a theoretical error model of a circular-type zone plate, the most commonly used types for CGH patterns, is suggested. The proposed error model is checked by simulations and experiments.

• 한국지반환경공학회 논문집
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• 제11권4호
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• pp.43-50
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• 2010

본 연구에서는 가솔린으로 오염된 토양에서 MTBE이용 분해균주를 분리하였으며, 분리한 각 균주의 MTBE 생분해특성을 파악하고자 하였다. 오염된 토양 내에서 MTBE 이용 혼합균주 중 총 18균주를 분리한 후, 18균주 중 3개의 균주(Flavobacterium, Pseudomonas, Achromobacter)에서 MTBE의 생분해가 나타났다. MTBE 이용 균주의 최적 생장인자는 배양온도 $30^{\circ}C$, pH 7, 균접종농도는 0.6g/mL로 조사되었다. Achromobacter, 혼합균주, Pseudomonas, 그리고 Flavobacterium의 MTBE 일차 분해계수는 0.072, 0.066, 0.047, $0.032hr^{-1}$로 조사되었다. 그리고 균접종농도를 고려한 MTBE 생분해속도는 1.302, 1.019, 0.523, 0.352mg/TSS g/hr로 관측되었다. MTBE 단독기질로 존재할때에 MTBE분해속도가 가장 높은 Achromobacter는 BTEX와 동시에 존재하였을 경우 다른 균주들에 비하여 낮은 MTBE 분해능을 나타내었다. 또한, MTBE 이용 혼합균주와 Flavobacterium은 MTBE와 BTEX 생분해 특성이 비슷한 것으로 나타났다.

• 한국환경농학회지
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• 제22권4호
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• pp.284-289
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• 2003

Mesoporous titanium oxo-phosphate(Ti-MCM)은 기존의 유기성 오염물질의 광분해제로 널리 이용되고 있는 $TiO_2$에 비해 표면적이 매우 넓은 장점이 있다. 그러므로 본 연구에서는 Ti-MCM에 의한 chlorothalonil의 흡착 및 광분해 특성을 $TiO_2$와 비교하였다. 합성된 Ti-MCM은 hexagonal 형태로 d-spacing이 4.1 nm이었다. 암조건에서 $TiO_2$에 의한 chlorothalonil의 흡착은 거의 일어나지 않았으나, Ti-MCM에 의한 흡착은 반응 1시간까지 25%로 급격히 증가하여 흡착평형에 도달하였다. UV조사 하에서 반응 9시간 후의 $TiO_2$와 Ti-MCM에 의한 chlorothalonil의 제거율은 각각 88%와 100%로 나타났다. 그러나 정치상태에서의 광분해 속도는 chlorothalonil과 Ti-MCM사이의 낮은 접촉에 의한 반응성의 감소로 느린 경향을 나타내었다. 또한 Ti-MCM에 의한 chlorothalonil의 분해효율은 용액의 초기 농도가 낮을수록, pH 7까지 반응용액의 pH가 높을수록 증가하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1624-1626
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• 1999

PD in defect of solid insulation system is very harmful since It often leads to deterioration of insulation by the combined action of the discharge ions bombarding the surface and the action of chemical compounds that are formed by the discharge. PD can indicate incipient failure, so it has been used to determine degradation of insulation. In this paper. we investigated PD in defects of solid insulation by using statical method and classified PD patterns with surface discharge, electrical tree and void discharge by using Kohonen network. we used peak charge, average discharge power, average discharge current, repetition rate, skewness, kurtosis, QN of the max pulse height vs. repetition rate $H_q(n)$ for analysis and classification.