• 전자공학회논문지
• /
• 제52권12호
• /
• pp.32-40
• /
• 2015

코드 분할 다중 접속 기법은 주파수 선택적 페이딩과 다중 경로 페이딩에 강인할 뿐만 아니라 주파수 재사용 효율이 좋으므로 수중 환경에서의 유망한 매체 접속 제어 기법으로 많은 연구가 진행되고 있다. 본 논문에서는 시변 수중 음향 채널에서 코드 분할 다중 접속 방식의 폐루프 전력 제어 기법을 설계한다. 본 기법에서는 싱크 노드가 센서 노드로부터 수신한 패킷의 수신 전력을 바탕으로 시변하는 상향 링크를 분석하고 각 센서 노드의 경로 손실의 크기를 포함한 제어 패킷을 센서 노드로 전송한다. 센서 노드는 이를 바탕으로 전력 제어를 수행함으로써 시변 수중 채널에서 효율적인 전력 제어가 가능하다.

• 한국미생물·생명공학회지
• /
• 제22권6호
• /
• pp.607-613
• /
• 1994

The Bacillus stearothermophilus arfI gene encoding a-arabinofuranosidase was isolated from the genomic library, cloned into pBR322, and subsequently transferred into the Escherichia coli HB101. The recombinant E. coli was selected from approximately 10,000 transformants screened by making use of its ability to produce a yellow pigment around the colony on the selective medium supplemented with p-nitrophenyl-$\alpha$-L-arabinofuranoside (pNPAf), a chromogenic substrate. The functional clone was found to harbor a recombinant plasmid, pKMG11 with an insertion of about 5 kb derived from the B. stearothermophilus chromosomal DNA. Identity of the arfI gene on the insert DNA was confirmed by a zymogram with 4-methylumbelliferyl-$\alpha$-L-arabinofuranoside as the enzyme substrate. The $\alpha$-arabinofuranosidase from the recombinant E. coli strain showed very high substrate specificity; the enzyme displayed high activity only with pNPAf among many other p- or $o$-nitrophenyl derivatives of several sugars, and acted only on arabinoxylan among various natural arabinose containing polysaccharides tested.

• The Plant Pathology Journal
• /
• 제27권2호
• /
• pp.128-137
• /
• 2011

Fifty two Macrophomina phaseolina isolates were recovered from 24 host plant species through the 14 Iranian provinces. All isolates were confirmed to species using species-specific primers. The colony characteristics of each isolate were recorded, including chlorate phenotype, relative growth rate at $30^{\circ}C$ and $37^{\circ}C$, average size of microsclerotia, and time to microsclerotia formation. The feathery colony phenotype was the most common (63.7%) on the chlorate selective medium and represented the chlorate sensitive phenotype of the Iranian Macrophomina phaseolina population. Meantime, inter simple sequence repeats (ISSR) Markers were used to assess the genetic diversity of the fungus. Unweighted pair-group method using arithmetic means (UPGMA) clustering of data showed that isolates did not clearly differentiate to the specific group according to the host or geographical origins, however, usually the isolates from the same host or the same geographic origin tend to group nearly. Our results did not show a correlation between the genetic diversity based on the ISSR and phenotypic characteristics. Similar to the M. phaseolina populations in the other countries, the Iranian isolates were highly diverse based on the phenotypic and the genotypic characteristics investigated and needs more studies using neutral molecular tools to get a deeper insight into this complex species.

• The Plant Pathology Journal
• /
• 제19권6호
• /
• pp.280-283
• /
• 2003

A soybean-sprout rot epidemic occurred in a mass production soybean sprout factory in 2000 and 2001 in Korea, which caused up to 20% production loss. Among the causal pathogenic bacteria and fungi, Pythium deliense was found to be the dominant pathogen of severe root and hypocotyls rot, particularly in recirculating water system. An average of 90% of the isolated fungi from the rotted sprout on potato dextrose agar were Pythium sp. The fungal density of Pythium in the sampled water was monitored in the recycled water system for 1 year using a selective medium (com meal agar with Pimaricin, 10 mg； Rifampicin, 10 mg； and Ampicillin, 100 mg per 1 liter). The drained water from the soybean-sprout cultivation always had a certain amount of fungus in it. The removal of Pythium from the recycling water system must be thorough, safe, and environment friendly. However, the pathogen in the water was easily found even after ozone and chlorine treatments, which were devised on the recycling system for the removal of microorganisms. 5-$\mu\textrm{m}$ pore size filter was applied and was able to successfully control the disease. As the sprout industry increasingly shifts into mass production, the demand for water will increase continuously. Recycling water for sprout production is eco-friendly. However, a process must be devised to be able to first decompose organic matters before Pythium zoospores are filtered.

• Journal of Microbiology
• /
• 제39권4호
• /
• pp.321-325
• /
• 2001

Baird-Parker agar with egg yolk/tellurite emulsion (BPA) is widely accepted as a medium for the enu-meration of Staphylococcus aureus in foods. Howerver, it is not vompletely selective and colonies of other genera of species could be similar to those of Staphylococcus aureus. Moreover, the strains of Staphylococcus aureus that are lecithinase negatrive could go unnoticed. Both facts could affect the counts. The aim of this study was to dtermine whether the enumeration of the colonies with the typical morphol-ogy of Staphylococcus aureus on BPA is sufficien to quantity this species in poultry meat. Forty chiken carcasses were tested for Staphylococcus aureus by surface plating using BPA, Results indicate that the predictiv value of the morphoogy of the colonies of BPA is 85.71% and 68.42% for typical and atypical colonies of Staphylococcus aureus, respectively. However, Staphylococcus aureus counts (after identification) and counts of typical colonies did not show any significant differences(P>0.05) and are significantly(P<0.001) correlated (r=0.996).These results suggest that , for screening purposes. enumeration of Staphylococcus aureus from poultry meat does not require any identification of stains. resulting in a saving of time and money.

• Mycobiology
• /
• 제34권1호
• /
• pp.22-29
• /
• 2006

Forty-one fungal species belonging to 15 fungal genera isolated from Egyptian soil and sugar cane waste samples were tested for their capacity of producing acidity and gluconic acid. For the tests, the fungi were grown on glucose substrate and culture filtrates were examined using paper chromatography analysis. Most of the tested fungi have a relative wide potentiality for total acid production in their filtrates. Nearly 51% of them showed their ability of producing gluconic acid. Aspergillus niger was distinguishable from other species by its capacity to produce substantial amounts of gluconic acid when it was cultivated on a selective medium. The optimized cultural conditions for gluconic acid yields were using submerged culture at $30^{\circ}C$ at initial pH 6.0 for 7 days of incubation. Among the various concentrations of substrate used, glucose (14%, w/v) was found to be the most suitable carbon source for maximal gluconic acid during fermentation. Maximum values of fungal biomass (10.02 g/l) and gluconic acid (58.46 g/l) were obtained when the fungus was grown with 1% peptone as sole nitrogen source. Influence of the concentration of some inorganic salts as well as the rate of aeration on the gluconic acid and biomass production is also described.

• 한국광학회지
• /
• 제6권4호
• /
• pp.296-301
• /
• 1995

광섬유격자와 단방향성 광섬유 loop mirror를 이용하여 단일모드로 발진하는 erbium첨가 광섬유레이저를 구성하였다. 이득매질인 erbium첨가 광섬유를 단방향성 loop내에 둠으로써 레이저광이 이득매질내에서 진행파를 이루도록 하고 loop 밖에서 반사 선폭이 0.2nm인 광섬유격자로 파장선택적 귀환시켜 주는 방식으로 공진기를 구성하였다. 수동형 광섬유 링공진기 형태의 광스펙트럼 분석기를 별도로 구성하여 광섬유레이저의 모드 스펙트럼을 관찰한 결과, 외부 온도변화로 인한 분 단위의 모드 튐을 제외하고는 대부분의 시간에 안정적인 단일모드 및 단일편광 상태의 특성을 나타냄을 확인할 수 있었다.

• Bulletin of the Korean Chemical Society
• /
• 제34권10호
• /
• pp.3059-3064
• /
• 2013

In this study transesterification of Triglycerides (TG) from Jatropha curcas oil (JCO) with methanol for production of biodiesel was investigated over cerium impregnated ZSM-5 catalysts. NaZSM-5 was synthesized in an alkaline medium and impregnated with cerium oxide by wet method using cerium nitrate as a source for cerium. They were characterized by X-ray diffraction (XRD), Thermogravimeteric analysis (TGA), $CO_2$-temperature programmed desorption, and $N_2$ adsorption/desorption analysis. XRD analysis showed decrease in intensity of the patterns with the increase in the ceria loading but crystallization of ceria to larger size is an evident for 10 and 15% loading. The optimal yield of transesterification process was found to be 90% under the following conditions: oil to methanol molar ratio: 1:12; temperature: $60^{\circ}C$; time: 1 h; catalyst: 5 wt %. Here the yield of fatty acid methyl ester (FAME) was calculated through $^1H$ NMR analysis. The investigation on catalyst loading, temperature, time and reusability illustrated that these ceria impregnated NaZSM-5's were found to be selective, recyclable and could yield biodiesel at low temperature with low methanol to oil ratio due to the presence of both Lewis and Bronsted basicity. Hence, from the above study it is concluded that ceria impregnated ZSM-5 could be recognized as a potential catalysts for biodiesel production in industrial processes.

• 한국미생물·생명공학회지
• /
• 제21권1호
• /
• pp.82-87
• /
• 1993

한국 전통 발효식품의 숙성에 절대 혐기성 세균이 관여하는지를 보기 위해 김치류와 장류 14종의 시료를 복합 BL 배지 혹은 bifidus 세균 선택 배지인 BS agar에 접종하여 절대 혐기적으로 배양한 결과 복합 BL 배지에서 $10^7$ ~ $10^8$/g 시료의 세균이 생장하였으며, BS agar에서는 $10^3$ ~ $10^6$/g 시료의 colony가 형성되었다. 이들은 모두 호기성 조건에서도 생장 할 수 잇었으며, BS 배지에서 생장하는 세균은 fructose-6-phosphate phosphoketolase를 합성하지 않는 것으로 나타났다. 또한 표준 Bifidobacterium속 세균은 3% NaCl을 함유하는 배지에서는 생장할 수 없었다. 이상의 결과로부터 김치류와 장류 등 염 농도가 높은 발표식품에는 bifidus균은 생장할 수 없다고 판단된다.

• Journal of Microbiology and Biotechnology
• /
• 제24권7호
• /
• pp.936-942
• /
• 2014

Using racemic (R,S)-2-(4-chlorophenyl)-3-methylbutyramide, an intermediate for the chiral pyrethroid insecticide Esfenvalerate, as a sole nitrogen source in a minimal medium, several strains with high enatioselectivity (${\geq}98%$) were isolated by enrichment techniques. One of the strains, LG 31-3, was identified as Burkholderia multivorans, based on physiological and morphological tests by a standardized Biolog station for carbon source utilization. A novel amidase was purified from B. mutivorans LG 31-3 and characterized. The enzyme exhibited (S)-selective amidase activity on racemic (R,S)-2-(4-chlorophenyl)-3-methylbutyramide. Addition of the racemic amide induced the production of the enantioselective amidase. The molecular mass of the amidase on SDS-PAGE analysis was shown to be 50 kDa. The purified amidase was subjected to proteolytic digestion with a modified trypsin. The N-terminal and internal amino acid sequences of the purified amidase showed a high sequence homology with those deduced from a gene named YP_366732.1 encoding indole acetimide hydrolase from Burkholderia sp. 383.