• 한국추진공학회지
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• 제4권4호
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• pp.9-17
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• 2000

준안정상인 $\beta$형 HNIW의 용해와 안정상인 $\varepsilon$형 HNIW의 성장 특성을 고려한 모델식을 물질수지와 한께 계산하는 방법으로 결정성장 속도와 용해 속도를 계산하였다. 제시된 모델은 용액을 매체로 하여 진행되는 $\beta$$\longrightarrow$$\varepsilon$전이 현상에 대한 속도론적 데이터를 모사 하는데 유용하였다. 2 단 모델을 이용한 유효 인수로부터, 격정성장 과정에서 표면 축적 단계의 영향은 작으며, 확산 의존성은 ethyl acetate와 chloroform의 혼합 용매 중 chloroform의 함량이 증가함에 따라 감소함을 보였다. 이들 속도론 적 계수들을 이용한 수치모사를 통하여 $\varepsilon$-HNIW의 입자 크기를 예측하는 것이 가능하였다.

• Journal of Microbiology and Biotechnology
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• 제22권1호
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• pp.25-33
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• 2012

The association of verotoxic E. coli and Acinetobacter spp. with various antibiotic-resistant, diarrhogenic, and nosocomial infections has been a cause for concern worldwide. E. coli and A. haemolyticus isolated on a number of selective media were screened for virulence factors, antibiotic resistance, and transformation of resistance genes. Out of 69 E. coli isolates obtained, 25 (35.23%), 14 (20.30%), and 28 (40.58%) were positive for Vtx1&2, Vtx1, and Vtx2, respectively, 49 (71.015%) for extendedspectrum beta-lactamases (ESBLs), 34 (49.28%) for serum resistance, 57 (82.61%) for cell surface hydrophobicity, 48 (69.57%) for gelatinase production, and 37 (53.62%) for hemolysin production. For the 14 A. haemolyticus isolates, only 2 (14.29%) in each case from all the samples investigated were positive for Vtx1, Vtx2 and Vtx1&2 respectively, 8 (57.14%) for ESBLs, 7 (50.00%) for serum resistance, 11 (78.57%) for cell surface hydrophobicity, 4 (28.57%) for gelatinase production, and 8 (57.14%) for hemolysin production. Although transformation occurred among the E. coli and Acinetobacter isolates (transformation frequency: $13.3{\times}10^{-7}-53.4^{-7}$), there was poor curing of the plasmid genes, a confirmation of the presence of stable antibiotic-resistant genes (DNA concentration between 42.7 and 123.8 ${\mu}g$) and intragenetic transfer of multidrug-resistant genes among the isolates. The isolates were potentially virulent and contained potentially transferable antibiotic resistance genes. Detection of virulence factors, antibiotic resistance genes, and transformation among these isolates is a very significant outcome that will influence approaches to proactive preventive and control measures and future investigations. However, continued surveillance for drug resistance among these bacteria and further investigation of the mechanism of action of their virulence factors are a necessity.

• Applied Biological Chemistry
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• 제41권3호
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• pp.219-223
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• 1998

작물 병해충에 대한 무공해 미생물 농약 개발의 일환으로 곤충 병원성 곰팡이 Metarhizium anisopliae의 분자생물학적 육종을 위해 이 균주의 형질전환계를 확립하였다. M. anisopliae의 원형질체를 제작하여 benomyl 약제에 대하여 저항성을 나타내는 Aspergillus flavus 유래의 ${\beta}-tubulin$ 유전자를 갖는 pBRG-4 plasmid DNA를 polyethylene glycol 방법으로 형질 전환하였다. 이 형질전환은 pBRG-4 DNA $50\;{\mu}g$당 10개의 효율로 이루어졌으며, 그 결과 야생형 균주들의 $2.5\;{\mu}g/ml$ 농도의 benomyl 존재 하에서도 성장이 억제되는데 반하여 선발된 형질전환체들은 $5.0\;{\mu}g/ml$ 농도의 benomyl 함유 배지에서도 잘 성장하였다. 또한 이 형질전환체들의 chromosomal DNA를 분리하여 Southern 분석한 결과 ${\beta}-tubulin$ 유전자가 homologous recombination에 의하여 M. anisopliae의 genome속에 삽입 되었음을 확인하였다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제13권1호
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• pp.31-40
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• 2009

In the present work transformation of dimensionless heat diffusion equation for the solution of moving boundary problems have been formulated. The formulation is based on 1-D, 2-D and 3-D, unsteady heat diffusion equations. These equations are rst turned int dimensionless form by using dimensionless quantities and their transformation was formulated in liquid and solid phases. The salient feature of this work is that during the transformation of dimensionless heat diffusion equation there arises a convective term $\tilde{v}$ which is responsible for the motion of interface in liquid as well as solid phase. In the transformed heat equation, a correction factor $\beta$ also arises naturally which gives the correct transformed flux at interface.

• 한국세라믹학회지
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• 제36권8호
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• pp.799-804
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• 1999

Composites of SiC-Si3N4 consisted of uniformly distributed elongated $\beta$-Si3N4 grains and equiaxed $\beta$-SiC grains were fabricated with $\beta$-SiC,. $\alpha$-Si3N4 Al2O3 and Y2O3 powders. By hot-pressing and subsequent annelaing elongated $\beta$-Si3N4 grains were grown via$\alpha$longrightarrow$\beta$ phase transformation and equiaxed $\beta$-Si3N4 composites increased with increasing the Si3N4 content owing to the reduced defect size and enhanced crack deflection by elongated $\beta$-Si3N4 grains and the grain boundary strengthening by nitrogen incorporation. Typical flexural strength and fracture toughness of SiC-40 wt% Si3N4 composites were 783 MPa and 4.2 MPa.m1/2 respectively.

• 호남수학학술지
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• 제46권2호
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• pp.313-334
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• 2024

In the current study, our aim is to define new generalized extended beta and hypergeometric types of functions. Next, we methodically determine several integral representations, Mellin transforms, summation formulas, and recurrence relations. Moreover, we provide log-convexity, Turán type inequality for the generalized extended beta function and differentiation formulas, transformation formulas, differential and difference relations for the generalized extended hypergeometric type functions. Also, we additionally suggest a generating function. Further, we provide the generalized extended beta distribution by making use of the generalized extended beta function as an application to statistics and obtaining variance, coefficient of variation, moment generating function, characteristic function, cumulative distribution function, and cumulative distribution function's complement.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 1986년도 추계학술대회
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• pp.509.1-509
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• 1986

Recent advances in recombinant DNA techniques have provided a tool for breeding of microorganisms of hyper production. Enzyme production by cloned microorganism has some advantages. They are ⅰ) Enzymes can be produced by a microorganism easily cultured ⅱ) Hyper production. ⅲ) In some cases, such as thermophilic enzyme gene is cloned in a mesophilic bacteria, the enzyme purification procedure can be simplified. One example, production of thermophilic ${\beta}$-galactosidase in B. subtilis will be presented. Bacillus stearothermophilus IAM 11001 produced three ${\beta}$-galactosidases, ${\beta}$-galactosidase I, II and III (${\beta}$-gal-I, II and III). By connecting restriction fragments of the chromosomal DNA to plasmid vector, followed by transformation of Escherichia coli, two ${\beta}$-galactosidase genes (bgaA and bgaB) located close to each other on the chromosome were cloned.

• Journal of Plant Biotechnology
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• 제2권3호
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• pp.135-142
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• 2000

The activity of promoter sequences was evaluated in garlic cells using the $\beta$-glucuronidase (GUS) gene as a reporter. Histochemical GUS assay indicated transient GUS activity in leaf, callus and root cells 48 hours after particle bombardment transformation. Quantitative fluorometric assays in extracts of transformed leaves demonstrated that the CsVMV promoter induced the highest level of gene expression, which was, on average, ten fold the level induced by CaMV35S and by the Arabidopsis Act2 promoters and two fold the level expression observed with a construct containing a double CaMV35S plus the untranslated leader sequence from AMV. No activity or very low levels were observed when cells were transformed with plasmids rontaining the typical monocot promoters, Actl, from rice or the Ubi-1, from maize. The green fluorescent protein (GFP) was also tested as a marker gene for garlic transformation. Intense fluorescence was observed in leaf, callus and root cells transformed with a construct containing the gfp gene under control of the CaMV35 Promoter. No fluorescence was detected when the gfp was under control of the Ubi-1 promoter.

• Journal of Welding and Joining
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• 제33권2호
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• pp.1-7
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• 2015

This article describes the basic technical concepts for applying the friction stir welding (FSW) process to titanium and its alloys. Titanium and its alloys are demanding applications of FSW. During FSW, a protective atmosphere is needed at the welding region to prevent the joints from oxidation due to the absorption of interstitial elements (O, N, and H) at high temperature. The process parameters for FSW have great influence on the microstructure and properties of the joints. No phase transformation occurred in CP Ti because FSW was achieved below the ${\beta}$-transus temperature. Therefore, the mechanical properties of the joints with CP Ti were governed by recrystallization and grain refinement. Furthermore, the strong crystallographic texture indicating <0001>//ND formed in the stir zone. On the other hands, the phase transformation occurred in Ti-6Al-4V alloy because the process temperature reached above ${\beta}$-transus temperature. For this reason, the mechanical properties of the joints with Ti-6Al-4V alloy were altered by not only recry stallization and grain refinement but also phase transformation during FSW. Engineers who want to get sound FSW joints with Ti-6Al-4V alloy have to pay attention to the control about process conditions.

• Journal of Plant Biology
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• 제39권2호
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• pp.93-98
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• 1996

In order to enhance the system of potato transformation and further regeneration, potato was transformed using the Agrobacterium tumefaciens harboring $\beta$-glucuronidase (GUS) gene. We found that a series fo modified medium ttained 100% shoot regeneration within 5 weeks after the preincubated explants on stage I medium were infected with Agrobacterium. Callus appeared at the cut edges of stem segments on stage II medium, mainly at the basal parts. Some explants started to form shoots after two to three weeks on stage III medium containing kanamycin (50 mg/L). When transferred to MS medium containing 200 mg/L kanamycin, 81% of the transformed shoots formed roots at the cut edge of the plantlets. In contrast, untrasformed shoots never rooted and became yellowish after few weeks under the same conditions. Southern and northern analysis indicated in vitro shoot regeneration on the callus derived from the potato explants, which were incubated with Agrobacteria. The regeneration cycle was shortened after the transformatin and finally the transformation efficiency was highly enhanced.