• The Plant Pathology Journal
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• 제18권2호
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• pp.57-62
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• 2002

In vivo expression technology (IVET) has been developed to study bacterial gene expression in Salmonella typhimurium during host infection. The expression of selected genes by IVET has been elevated in vivo but not in vitro. The selected genes turned out to be important for bacterial virulence and/or pathogenicity. IVET depends on a synthetic operon with a promoterless transcriptional fusion between a selection marker gene and a reporter gene. The IVET approach has been successfully adapted in other bacterial pathogens and plant-associated bacteria using different selection markers. Pseudomonas putida suppresses citrus root rot caused by Phytophthora parasitica and enhances citrus seedling growth. The WET strategy was adapted based on a transcriptional fusion, pyrBC'-lacZ, in P. putida to study the bacterial traits important far biocontrol activities. Several genes appeared to be induced on P. parasitica hyphae and were found to be related with metabolism and regulation of gene expression. It is likely that the biocontrol strain took a metabolic advantage from the plant pathogenic fungus and then suppressed citrus root rot effectively. The result was parallel with those from the adaptation of IVET in P. fluorescens, a plant growth promoting rhizobacteria (PGPR). Interestingly, genes encoding components for type III secretion system have been identified as rhizosphere-induced genes in the PGPR strain. The type III secretion system may play a certain role during interaction with its counterpart plants. Application of IVET has been demonstrated in a wide range of bacteria. It is an important strategy to genetically understand complicated bacterial traits in the environment.

• 대한전자공학회논문지TC
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• 제42권2호
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• pp.39-48
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• 2005

Mobile IP 망의 핸드오버 지연 및 부하 감소를 위해 HMIPv6에서는 MAP을 이용하여 지역 이동성 제어 기능을 제공한다. 이동단말이 방문 망에 진입 시 새로운 MAP을 결정하는데 기존의 HMIPv6에서는 가장 먼 거리의 MAP을 우선적으로 선택하는 거리 기반 알고리즘을 사용한다. 이 방식은 소극적인 이동을 하는 단말도 가장 먼 거리의 MAP을 선택하게 하여 핸드오버 지연과 패킷 은실이 증가한다는 문제를 가지고 있다. 본 논문에서는 기존의 거리 기반 알고리즘에 의해 선택되는 기본 MAP 외에 2차 MAP을 이용하여 이러한 문제를 해결하는 새로운 기법을 제안하였다. 본 논문에서 제안한 새로운 기법과 기존의 HMIPv6 기법에서의 핸드오버 시 지연시간과 패킷 손실률에 대하여 성능 비교를 하여 본 논문에서 제안한 2차 MAP 이용 기법의 우수함을 증명하였다.

• The Plant Pathology Journal
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• 제33권3호
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• pp.296-306
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• 2017

Sugarcane mosaic virus (SCMV) is one of the most damaging viruses infecting sugarcane, maize and some other graminaceous species around the world. To investigate the genetic diversity of SCMV in Iran, the coat protein (CP) gene sequences of 23 SCMV isolates from different hosts were determined. The nucleotide sequence identity among Iranian isolates was more than 96%. They shared nucleotide identities of 75.5-99.9% with those of other SCMV isolates available in GenBank, the highest with the Egyptian isolate EGY7-1 (97.5-99.9%). The results of phylogenetic analysis suggested five divergent evolutionary lineages that did not completely reflect the geographical origin or host plant of the isolates. Population genetic analysis revealed greater between-group than within-group evolutionary divergence values, further supporting the results of the phylogenetic analysis. Our results indicated that natural selection might have contributed to the evolution of isolates belonging to the five identified SCMV groups, with infrequent genetic exchanges occurring between them. Phylogenetic analyses and the estimation of genetic distance indicated that Iranian isolates have low genetic diversity. No recombination was found in the CP cistron of Iranian isolates and the CP gene was under negative selection. These findings provide a comprehensive analysis of the population structure and driving forces for the evolution of SCMV with implications for global exchange of sugarcane germplasm. Gene flow, selection and somehow homologous recombination were found to be the important evolutionary factors shaping the genetic structure of SCMV populations.

• The Plant Pathology Journal
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• 제37권6호
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• pp.619-631
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• 2021

Alfalfa mosaic virus (AMV), an economically important pathogen, is present worldwide with a very wide host range. This work reports for the first time the infection of Vinca minor and Wisteria sinensis with AMV using RNA sequencing and reverse transcription polymerase chain reaction confirmation. De novo assembly and annotating of contigs revealed that RNA1, RNA2, and RNA3 genomic fragments consist of 3,690, 2,636, and 2,057 nucleotides (nt) for IR-VM and 3,690, 2,594, and 2,057 nt for IR-WS. RNA1 and RNA3 segments of IR-VM and IR-WS closely resembled those of the Chinese isolate HZ, with 99.23-99.26% and 98.04-98.09% nt identity, respectively. Their RNA2 resembled that of Canadian isolate CaM and American isolate OH-2-2017, with 97.96-98.07% nt identity. The P2 gene revealed more nucleotide diversity compared with other genes. Genes in the AMV genome were under dominant negative selection during evolution, and the P1 and coat protein (CP) proteins were subject to the strongest and weakest purifying selection, respectively. In the population genetic analysis based on the CP gene sequences, all 107 AMV isolates fell into two main clades (A, B) and isolates of clade A were further divided into three groups with significant subpopulation differentiation. The results indicated moderate genetic variation within and no clear geographic or genetic structure between the studied populations, implying moderate gene flow can play an important role in differentiation and distribution of genetic diversity among populations. Several factors have shaped the genetic structure and diversity of AMV: selection, recombination/reassortment, gene flow, and random processes such as founder effects.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제10권3호
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• pp.221-230
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• 2004

원격 모니터링 시스템이란 네트웍에 분산된 호스트 혹은 원격 어플리케이션의 상태를 실시간으로 모니터링 하는 시스템이다. 네트웍에 분산된 호스트들은 다양한 플랫폼을 갖추고 있는 것이 현실이다. 하지만, 기존의 모니터링 시스템들은 플랫폼에 의존적인 성격을 띠고 있다. 네트웍을 통해서 모니터링을 하기 때문에 잠재적인 네트웍의 문제발생에 대한 적절한 대응이 필요하지만, 기존의 모니터링 시스템들은 네트웍의 문제에 대해서 적절하게 대응을 못하고 있다. 그리고 호스트의 상태를 변화시키는 요인은 호스트의 시스템 자원보다는 어플리케이션의 상태변화가 주 요인이 되고 있지만, 기존의 시스템들은 주로 호스트의 상태정보만 모니터링을 하고 있다. 따라서, 분산된 호스트들의 플랫폼에 독립적이고, 네트웍의 잠재적인 문제발생을 적절하게 대응을 할 수 있고, 호스트의 상태정보 보다는 호스트의 어플리케이션의 상태정보를 모니터링 하는 시스템이 필요한 실정이다. 본 논문에서는 네트웍에 분산된 어플리케이션의 실시간 모니터링을 통해서 어플리케이션 상태를 효과적으로 관리할 수 있는 모니터링 시스템인 RAMS (Remote Applications Monitoring System)의 설계 및 구현을 제시한다. 이 시스템은 네트웍에 분산된 호스트들의 효과적인 관리를 위해 호스트 어플리케이션의 상태를 모니터링 한다. RAMS는 모니터링 대상인 호스트 어플리케이션의 모니터링을 담당하는 Agent, 호스트의 등록, 관리를 담당하는 Manager로 구성된다. Manager와 Agent는 네트웍 단절 혹은 호스트 failure의 상황에도 자동으로 복구가 가능할 수 있도록 JINI를 최대한 활용함으로써 다른 시스템에 비해 시스템의 구성 및 관리가 용이한 특성을 갖는다.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.422-428
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• 2015

This paper proposes a high performance reversible watermarking (RW) scheme based on a novel compensation strategy. RW embeds data into a host image by modifying its pixel values slightly. It is found that certain modified pixels can be compensated to their original values during the proposed embedding procedure. The compensation effect in the RW scheme can improve the marked image quality significantly. By incorporating the pixel selection method, a higher quality image is obtained, which is verified by extensive experiments.

• 한국정보전자통신기술학회논문지
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• 제6권4호
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• pp.272-277
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• 2013

In this paper the effect of instability and chaos in optical fiber networks based on the Internet is described. Nonlinear optical fiber effect especially Brillouin scattering in networks has emerged as the essential means for the construction of active optical devices used for all-optic in-line switching, channel selection, amplification, oscillation in optical communications and a host of other applications. The inherent optical feedback by the back-scattered Stokes wave in optical networks also leads to instabilities in the form of optical chaos. This paradigm of optical chaos in fiber Internet serves as a test for fundamental study of chaos and its suppression and exploitation in practical application in optical fiber communication. This paper attempts to present a survey and some of our research findings on the nature of Brillouin chaotic effect on Internet based optical communication.

• 한국정보전자통신기술학회논문지
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• 제1권1호
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• pp.61-66
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• 2008

In this paper the effect of instability and chaos in optical fiber networks based on the Internet is described. Nonlinear optical fiber effect especially Brillouin scattering in networks has emerged as the essential means for the construction of active optical devices used for all-optic in-line switching, channel selection, amplification, oscillation in optical communications and a host of other applications. The inherent optical feedback by the back-scattered Stokes wave in optical networks also leads to instabilities in the form of optical chaos. This paradigm of optical chaos in fiber Internet serves as a test for fundamental study of chaos and its suppression and exploitation in practical application in optical fiber communication. This paper attempts to present a survey and some of our research findings on the nature of Brillouin chaotic effect on Internet based optical communication.

• Journal of Microbiology and Biotechnology
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• 제2권2호
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• pp.129-134
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• 1992

Segregational instability of a recombinant plasmid, pDML6, encoding extracellular $\beta$-lactamase in Streptomyces lividans PD6 was characterized by growth kinetic analysis. The quantitative determination of the plasmid harbored in the mycelia was evaluated with mycelia fragmented mechanically, and also with colonies regenerated from protoplasts. Conditions for the formation of protoplasts and regeneration of protoplasts were established. The maximal specific growth rates of the host strain and the plasmid-harboring strain in a chemically defined medium without selection pressure were the same. The probability of plasmid loss from the harbouring cells was higher at higher growth rates. Mathematical models for the prediction of cell growth, substrate uptake, and accumulation of the cloned gene product were developed.

• Journal of Microbiology and Biotechnology
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• 제10권2호
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• pp.272-274
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• 2000

Temperate bacteriophage P2 has a nonessential gene called old(overcoming lysoginization defection). In the presence of old, the growth of the host (Escherichia coli) with recBC- genotype is ingibited, and another bacteriophage, lambda, cannot superinfect. The Old protein has been shown to possess an exonuclease actibity. Three mutant P2s(old 1, old 17, old 49) which did gene was coned into expression vectors to produce hexahistidine-tagged proteins. The proteins were affinity-purified and shown to lose its exonuclease activity on both double-stranded and single-stranded DNA substrates. Thus, it was concluded that the lambda exclusion was related to Old's exonuclease activity.