• 한국식품위생안전성학회지
• /
• 제15권2호
• /
• pp.176-178
• /
• 2000

V. parahaemolyticus를 균주로 alkaline protease 생산을 위한 질소원의 종류, skim milk농도, NaCl농도, 금속이온의 종류를 조사하였다. 질소원인 peptone, tryptone, casamino acid, ski milk, phyton peptone중에서는 skim milk에서 활성이 월등히 높게 나타났고, skim milk의 농도에 따른 실험에서는 2%일 때 활성이 가장 높게 나타났다. NaCl의 농도에 따른 실험에서는 0%일 때 활성이 가장 높았고 농도가 높아질수록 활성이 낮아졌다. 금속이온에 따른 활성을 보면 금속이온이 들어가지 않았을 때 활성이 가장 높게 나타났고, 금속이온을 첨가하므로써 활성이 급격히 떨어졌다. 또한 CoCl$_2$, CuCl$_2$, HgCl가 첨가되었을 때는 활성이 전혀 나타나지 않았다.

• 전기전자학회논문지
• /
• 제4권2호
• /
• pp.225-232
• /
• 2000

전압원 인버터의 PWM 신호에 삽입되는 데드 타임은 인버터 출력 파형을 왜곡시키고, 토크 리플을 발생시켜 유도 전동기의 제어 성능을 떨어뜨린다. 본 논문에서 벡터 제어 유도 전동기의 데드 타임 보상 방법이 제안된다. 제안된 방법은 2상 정지 좌표계에서 인버터 출력 기준전압에 보상 전압을 더하는 전향 보상에 근거한다. 제안된 방법은 부가적인 하드웨어 없이 소프트웨어적으로 실현 가능하다. 실험 결과를 통하여 제안된 방법의 타당성과 유용성을 확인한다.

• 한국식품영양과학회지
• /
• 제42권4호
• /
• pp.627-632
• /
• 2013

본 연구는 phytate를 myo-inositol과 무기태인으로 분해시키는 효소인 phytase 생산균주의 분리 및 현미의 phytate 저감 최적 온도 및 pH에 관한 것이다. 먼저 phytase 활성 측정을 통하여 우수한 phytase 활성을 가지는 균주를 김치로부터 분리 및 선발하고 내산성과 내열성 실험으로 균주의 특성을 파악하고, 당 이용성 조사 및 16S rRNA sequence 분석으로 L. sakei가 동정되어 이 균주를 L. sakei Wikim001으로 명명하였다. L. sakei Wikim001에 의한 현미의 phytate 분해능을 확인하였으며, L. sakei Wikim001의 현미의 phytate 분해의 적정반응 pH는 5.0~6.5이며 온도는 $30{\sim}40^{\circ}C$.로 나타났다.

• Wind and Structures
• /
• 제24권1호
• /
• pp.59-78
• /
• 2017

Non-stationarity and non-Gaussian property are two of the most important characteristics of wind. These two features are studied in this study based on wind speed records measured at different heights from a 325 m high meteorological tower during the synoptic wind storms. By using the time-frequency analysis tools, it is found that after removing the low frequency trend of the longitudinal wind, the retained fluctuating wind speeds remain to be asymmetrically non-Gaussian distributed. Results show that such non-Gaussianity is due to the weak-stationarity of the detrended fluctuating wind speed. The low frequency components of the fluctuating wind speeds mainly contribute to the non-zero skewness, while distribution of the high frequency component is found to have high kurtosis values. By further studying the decomposed wind speed, the mechanisms of the non-Gaussian distribution are examined from the phase, turbulence energy point of view.

• 대한기계학회논문집B
• /
• 제27권3호
• /
• pp.334-346
• /
• 2003

An experimental study was carried out to investigate near-wake characteristics of an elliptic airfoil oscillating in pitch. The airfoil was sinusoidally pitched about the half chord point between -5$^{\circ}$and +25$^{\circ}$angles of attack at the freestream velocities of 3.4 and 23.1 m/s. The corresponding Reynolds numbers based on the chord length were 3.3$\times$10$_{4}$ and 2.2$\times$10$^{5}$ , respectively. A hot-wire anemometer was used to measure the near-wake flow variables at the reduced frequency of 0.1. Ensemble-averaged velocity and turbulence intensity profiles were presented to examine the near-wake characteristics depending on the Reynolds number. The axial velocity deficit in the near-wake region tends to decrease with the increase in the Reynolds number as found in many stationary airfoil tests. Turbulence intensity in the near-wake region have a tendency to decrease with the -increase in the Reynolds number during the pitch-up motion, whereas it shows different feature during the pitch-down motion according to the separation characteristics.

• 미생물학회지
• /
• 제19권4호
• /
• pp.179-185
• /
• 1981

한강 수계에서 SDBS (Sodium Dodecyl Benzene Sulfonate)를 유일한 탄소원으로 가지는 최소배지에서 서란 120 균주중 $4^{\circ}C$에서 생장이 좋은 8균주를 선택하여 동정하였으며. 이들의 온도에 따른 생장파 분해능을 흡광도 분석기를 이용하여 측정하였다. 동정 결과. Ps. fluorescens가 4균주, Ps. putida가 2균주 이었다. 이들중 Ps. fluorescens LP6, Ps. lido Lei, Ps. fluorescens LS 6의 비생장율은 모두 $25^{\circ}C$에서 가장 높은 값을 나타냈으나 정체기에서의 균체량은 $5^{\circ}C$ 에서 가장 높았다. 따라서 이들 3 균주는 faculfative psychrophilic bacteria로 사료된다. 한편 SDBS의 분해는 세포가 정체기에 들어가면서 시작되었으며, 분해능은 $25^{\circ}C$C에서 가장 좋았다.

• KSBB Journal
• /
• 제6권1호
• /
• pp.69-77
• /
• 1991

When S. fradiae was cultured in S medium, it stavted to produce neomycin in the middle of stationary phase of growth. Antibitoic production is regulated not only by glucose but also by metabolites formed from glucose. A chemically defined minimal salt broth was developen for the study of metabolites activating produition of antibiotic in a neomycin producer. When growth and production or antibiotic in minimal salt broth was examined with a full grown or a vefctativc mycelium, the medium was found not to be good for the growth, but to be good enough for the production of antibiotic with a full grown mycelium. When many carbotlydrates, organic acids, or alcohol were supplmented with instead of glucose in the medium suspcndcn with a full grown mycelium, the amount of antibiotic produced in the medium containing fumaratc was 5 times more than that in the medium with glucose. Further study indicated that the medium is not good also for the growth but good for the production of antibiotic. The antibiotic produced in this medium was identified to be neomycin. The activation of the production of neomycin by fumarate was further confirmed in a complex medium. Fuinarate is suspected to initiate and to activate the biosynthesis of neomycin at the gene level.

• KSBB Journal
• /
• 제21권4호
• /
• pp.236-240
• /
• 2006

대장균을 회분배양하면서 알칼리소비속도를 온라인으로 모니터하고, 대수증식기에 IPTG로 재조합 단백질의 발현을 유도시키면 알칼리소비속도가 급격하게 감소하는 것을 확인 할 수 있다. 회분배양을 서로 다른 조건에서 7회 실시하고 ${\beta}$-galactosidase의 발현량과 발현유도 직후 알칼리 소비속도의 감소를 비교하여 알칼리소비의 감소가 클수록 발현량이 증가한다는 것을 알 수 있었다. 그러나 IPTG를 재투입하여도 발현량은 증가하지 않았고 배지를 추가로 공급하면 발현량이 증가한다는 것을 확인하였다. 이와 같은 결과로부터 외래단백질의 발현속도는 초기의 IPTG 투입시 결정되고 이후의 재조합단백질의 생산은 배지의 공급에 의하여 제한된다고 판단할 수 있다. 이와 같은 알칼리 소비속도는 Casamino acid를 질소원으로 사용할 경우 관찰 되었으나 Yeast extract를 유일한 탄소원으로 사용할 경우에는 관찰되지 않았다.

• 전기의세계
• /
• 제29권4호
• /
• pp.247-255
• /
• 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
• /
• 제22권4호
• /
• pp.484-493
• /
• 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.