• 전기의세계
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• 제29권4호
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• pp.247-255
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• 1980

In this study, an application of Finite Element Method which, in principle, based on variational calculus has been presented for the two-dimensional analysis of magnetic flux distribution in the shell type core of single phase transformer. The necessary stationarity condition of energy functional and boundary conditions were determined under the assumptions that the electromagnetic field considered is stationary and that the effect of eddy current is negligible. In the process of application the domain of magnetic field was divided into triangle subsectional elements and then the matrix equations were constructed for the respective triangular element and for those of all after the manipulation of minimization process to the vector potential of magnetic field at the each vertex of the element. Furthermore the numerical computation for the equations was guided by the Gaussian Elimination Methods. As the results obtained, it is found that the aspect of magnetic flux distribution inside the core as well as the leakage flux profile at the vicinity of the inner leg of the core is not much different from the well-known distribution profile of magnetic flux, however, the procedure shows to possess the merit of the uniquely deterministic nature for the flux distribution at the desired points.

• Journal of Microbiology and Biotechnology
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• 제22권4호
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• pp.484-493
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• 2012

BolA protein homologs are widely distributed in nature. In this report, we have studied for the first time YrbA, the only BolA homolog present in Escherichia coli, which we have renamed ibaG. We have constructed single and multiple ibaG mutants, and overexpressed ibaG in wild-type strains, in order to characterize this gene. The ibaG phenotypes are different from the bolA-associated round morphologies or growth profiles. Interestingly, ibaG and bolA single-and double-deletion mutants grow faster and have higher viabilities in rich media, whereas the overexpressed strains are significantly growth impaired. However, the mutant strains have lower viabilities than the wild type in the late stationary phase, indicating that both bolA and ibaG are important for survival in difficult growth conditions. bolA, as a transcription factor, binds to some promoters, but ibaG does not interact with the same DNA regions. We have determined that ibaG is transcribed in an operon with the murA gene, involved in the synthesis of peptidoglycan precursors. ibaG was also seen to change its mRNA expression pattern in response to acidic stress. ibaG may thus represent a new gene involved in cell resistance against acid stress.

• Journal of Microbiology and Biotechnology
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• 제14권4호
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• pp.766-771
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• 2004

Julong 601, a Gram-positive anaerobic bacterium strain capable of cleaving the C-ring of isoflavones daidzein and genistein, was isolated from human feces. BLAST search revealed that its complete 16S rDNA gene sequence has 99% similarity to Eubacterium ramulus. Metabolites of daidzein and genistein were determined as O-desmethylangolensin (O-Dma) and 2-(4-hydroxyphenyl) propionic acid (2-HPPA), respectively, based on UV, EI-MS, and $^1H$ and ^{13}C$ NMR spectral analyses. Enantiomers of O-Dma and 2-HPPA were isolated by chiral stationary-phase HPLC (CSP HPLC). Cleavage of the C-ring of daidzein and genistein by strain Julong 601 was highly enantioselective. Specific rotation ([$\alpha]_D$) and circular dichroism (CD) spectra of the enantiomers are reported here for the first time. Biotransformation kinetics of daidzein and genistein indicated that the C-ring of genistein has a higher susceptibility to bacterial degradation than that of daidzein.

• 한국미생물·생명공학회지
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• 제20권2호
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• pp.183-189
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• 1992

Bacteriocin 생산균주인 Lactococcus sp. 111-2의 최적 배양조건과 배양 특성을 검토하였다. 탄소원은 glucose 20g/l, 질소원은 casein acid hydrolyzate 15g/l, 무기염류는 sodium acetate 3g/l와 ammonium citrate 2g/l가 bacteriocin 생성에 많은 영향을 주는 것으로 타났으며, 배지 pH는 6.2, 발효온도는 $35^{\circ}C$일 때 높은 생성수율을 보였다. 선발균주는 증식 및 항균물질의 생성에 riboflavin과 pantotheinc acid의 비타민을 요구하였다. 회분식 발효시 항균성물질의 생산패턴은 배양 12시간에 3,894IU/ml로 최대를 나타냈으며 균체생성은 배양 8.5시간에 정상기에 도달하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.633-638
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• 2002

The vacuum cleaner that has no dust bag generates very high level annoying noise. The dominant noise source is the 2$\^$nd/ BPF tone of the rotating impeller. In order to reduce the noise, we identify the acoustic characteristics and reduce the noise of the vacuum cleaner and centrifugal fan. The resonance phenomenon is observed in blade passages and we found out that the resonance frequency is very close to the 2$\^$nd/ BPF. In order to reduce this high-level peak noise, new impeller is designed in this paper. The trailing edge of new impeller is inclined and this makes the flow interactions between the rotating impeller and the stationary diffuser vane occurs with some phase shift. The performance of new impeller is similar to the old one but the overall SPL is reduced about 3.6dBA. The SPL of BPF is reduced about 6dBA and 2$\^$nd/ BPF is reduced about 20dBA. The vacuum cleaner, which uses newly developed centrifugal fan, generate more comfortable noise than the old model and the strong tonal sound was dramatically reduced.

• 한국식물병리학회지
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• 제14권5호
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• pp.376-381
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• 1998

Xanthomonas campestris pv. glycines 8ra causes bacterial pustule disease on susceptible soybean leaves and produces a bacteriocin, named glycinecin, against related bacteria such as Xanthomonas campestris pv. vesicatoria. The antimicrobial activity of the glycinecin was effective to most tested Xanthomonas species. X. c. pv. glycines 8ra was able to produce the glycinecin in liquid media as well as solid media. Maximal productivity of glycinecin was obtained at 3$0^{\circ}C$ in the early stationary phase of growth of the X. c. pv. glycines 8ra. The production of glycinecin was not dependent on the initial inoculum level but on cell density. Glycinecin was very sensitive to proteolytic enzymes such as trypsin and proteinase K but resistant to DNase and RNase. The culture supernatant of X. c. pv. glycines 8ra retained some of its antimicrobial activity after 15 min at 6$0^{\circ}C$. It is stable at wide range of pH. The glycinecin showed the bactericidal activity after the adsorption of the glycinecin to the sensitive bacterial cell.

• The Plant Pathology Journal
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• 제29권3호
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• pp.323-329
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• 2013

The stationary-phase sigma factor, RpoS, influences the expression of factors important in survival of Pseudomonas chlororaphis O6 in the rhizosphere. A partial proteomic profile of a rpoS mutant in P. chlororaphis O6 was conducted to identify proteins under RpoS regulation. Five of 14 differentially regulated proteins had unknown roles. Changes in levels of proteins in P. chlororaphis O6 rpoS mutant were associated with iron metabolism, and protection against oxidative stress. The P. chlororaphis O6 rpoS mutant showed increased production of a pyoverdine-like siderophore, indole acetic acid, and altered isozyme patterns for peroxidase, catalase and superoxide dismutase. Consequently, sensitivity to hydrogen peroxide exposure increased in the P. chlororaphis O6 rpoS mutant, compared with the wild type. Taken together, RpoS exerted regulatory control over factors important for the habitat of P. chlororaphis O6 in soil and on root surfaces. The properties of several of the proteins in the RpoS regulon are currently unknown.

• 미생물학회지
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• 제42권4호
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• pp.239-245
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• 2006

Leucine-responsive Regulatory Protein (Lrp)는 global 조절 단백질로서 아미노산의 합성 및 분해 작용과 pilin 생합성을 포함하는 다양한 대사기능을 조절하는데 관여한다. 또한 Lrp가 대장균의 성장 정지기의 유전자 발현에 매우 중요한 역할을 하는 것으로 최근의 여러 실험 결과에서 밝혀지고 있다. 따라서 본 총설에서는 세균들이 영양부족 등의 환경적인 스트레스상황을 어떻게 인지하고 유전자 발현 조절에 그 정보를 반영해 나가는지를 제시해 주는 종은 모텔 시스템으로서 Lrp의 생화학적 특성을 기술하였다.

• KSBB Journal
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• 제18권6호
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• pp.461-465
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• 2003

질소함유 폐수를 생물학적으로 효과적으로 처리하기 위한 전 단계로서 탈질 균을 분리하여 최종 선정된 균주의 분해특성을 조사한 결과 다음과 같은 결론을 얻었다. 분리된 5개 균주 가운데 DWS3가 세포성장과 질산성질소 제거율이 가장 우수하여 최종 분리 균주로 선정하였다. DWS3를 동정한 결과 Pseudomonas DWS로 명명하였다. 반 유동성 사면배지에 배양한 결과 녹색을 띠었으나, 탈질능을 갖는 균주의 활성에 따라 배지의 색이 녹색에서 암녹색으로 변환되었다. Pseudomonas DWS는 4시간 정도의 유도기를 거쳐 18시간에 최대 증식을 나타내었으며, 균의 생육속도와 비례하여 질산성질소의 제거율이 증가하는 것으로 나타났다. Pseudomonas DWS의 온도별 특성은 3$0^{\circ}C$에서 성장과 탈질율이 99% 우수하게 나타났으나, 탈질균 성장에 적합한 초기 pH는 7∼8에서 질산성 질소가 99% 이상 거의 모두 제거되었다. Pseudomonas DWS는 질산성 질소 농도에 관계없이 9시간 이내에 배지의 질산성 질소가 약 50%가 제거되었으며, 18시간 경과 후 99% 이상 질산성 질소가 제거되었다. 따라서 Pseudomonas DWS는 질소화합물을 다량 포함된 하, 폐수의 생물학적 처리에 효과적으로 이용 될 수 있는 것으로 사료된다.

• 한국균학회지
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• 제11권3호
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• pp.109-114
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• 1983

Aspergillus phoenicis의 ${\beta}-galactosidase$ 활성을 ONPG와 lactose를 기질로서 사용하여 조사하였다. 이 효소 활성은 성장의 대수기 동안은 서서히 증가하였으나 정지기가 시작되면서 급격하게 감소하였다. 또한 이 효소는 높은 온도에서도 좋은 효소 활성을 유지하였으며, 산성 pH에서 최고의 효소활성을 나타내었다. ${\beta}-galactosidase$는 lactose보다 ONPG에 대한 기질의 친화력이 더 좋았으며, 효소 활성도 ONPG의 경우가 더 높았다. Lactose의 가수분해율은 반응액중의 lactose의 농도가 낮을 수록 높았으며, 사용균의 무게에 따라 초기에는 증가하다가 어느 수준 이상에서 부터는 점근값을 나타내었다. 효소의 활성은 효소의 고정 방법 및 조건에 영향을 받았으며, matrix의 가교가 pH 7.2 및 0.35 vol. %의 glutaraldehyde 농도에서 행하여졌을 때, 가장 높은 효소 활성을 보였다.