• Journal of Internet Computing and Services
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• v.5 no.6
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• pp.21-30
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• 2004

In Ad-Hoc network, the cluster structure enables effective use of multiple channels, reduces the number of control messages, and increase the scalability of network, Also, it is employed for reducing the number of broadcast messages in an Ad-Hoc network. With the consideration of these advantages, it is desirable that a cluster structure keeps a few clusters in the network, Generally, the cluster formation scheme based on connectivity yields fewer clusters than the other schemes. However, the connectivity based scheme may yield even more clusters than the other schemes according to the network topology. In this paper, a cluster formation scheme dividing the cluster formation into two phases is proposed. In the first phase, the lowest connectivity host in neighborhood initiates the cluster formation. Then, an adjustment procedure for affiliating a lot of the lowest connectivity hosts is employed. In the second phase, the hosts which were not affiliated to the first phase clusters are grouped into one or more clusters through criterions of connectivity and host ID. As a result, the proposed scheme yields a fewer clusters compared with existing other schemes in fully distributed method. The simulation results proves that our scheme is better than LIDCP(3) and HCCP(3).

• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.315-322
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• 2004

Several arguments have been presented in the literature to support the connection between radio halos and cluster mergers. The spectral index distributions of the halos in A665 and A2163 provide a new strong confirmation of this connection, i.e. of the fact that the cluster merger plays an important role in the energy supply to the radio halos. Features of the spectral index (flattening and patches) are indication of a complex shape of the radiating electron spectrum, and are therefore in support of electron reacceleration models. Regions of flatter spectrum are found to be related to the recent merger. In the undisturbed cluster regions, instead, the spectrum steepens with the distance from the cluster center. The plot of the integrated spectral index of a sample of halos versus the cluster temperature indicates that clusters at higher temperature tend to host halos with flatter spectra. This correlation provides further evidence of the connection between radio emission and cluster mergers.

• Journal of The Korean Astronomical Society
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• v.44 no.5
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• pp.195-200
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• 2011

We have revisited the ACS Virgo Cluster Survey (ACSVCS), a Hubble Space Telescope program to obtain ACS/WFC g and z bands imaging for a sample of 100 early-type galaxies in the Virgo Cluster. In this study, we examine 51 nucleated early-type galaxies in the ACSVCS in order to look into the relationship between the photometric and structural properties of stellar nuclei and their host galaxies. We morphologically dissect galaxies into five classes. We note that (1) the stellar nuclei of dwarf early-type galaxies (dS0, dE, and dE,N) are generally fainter and bluer with g > 18.95 and (g-z) < 1.40 compared to some brighter and redder counterparts of the ellipticals (E) and lenticular galaxies (S0), (2) the g-band half-light radii of stellar nuclei of all dwarf early-type galaxies (dS0, dE, and dE,N) are smaller than 20 pc and their average is about 4 pc, and (3) the colors of red stellar nuclei with (g - z) > 1.40 in bright ellipticals and lenticular galaxies are bluer than their host galaxies colors. We also show that most of the unusually "red" stellar nuclei with (g-z) > 1.54 in the ACSVCS are the central parts of bright ellipticals and lenticular galaxies. Furthermore, we present multi photometric band color - color plots that can be used to break the age-metallicity degeneracy particularly by inclusion of the thermally pulsing-asymptotic giant branch (TP-AGB) phases of stellar evolution in the stellar population models.

• Journal of Microbiology and Biotechnology
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• v.29 no.12
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• pp.1931-1937
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• 2019

The heterologous expression of the Streptomyces natural product (NP) biosynthetic gene cluster (BGC) has become an attractive strategy for the activation, titer improvement, and refactoring of valuable and cryptic NP BGCs. Previously, a Streptomyces artificial chromosomal vector system, pSBAC, was applied successfully to the precise cloning of large-sized polyketide BGCs, including immunosuppressant tautomycetin and antibiotic pikromycin, which led to stable and comparable production in several heterologous hosts. To further validate the pSBAC system as a generally applicable heterologous expression system, the daptomycin BGC of S. roseosporus was cloned and expressed heterologously in a model Streptomyces cell factory. A 65-kb daptomycin BGC, which belongs to a non-ribosomal polypeptide synthetase (NRPS) family, was cloned precisely into the pSBAC which resulted in 28.9 mg/l of daptomycin and its derivatives in S. coelicolor M511(a daptomycin non-producing heterologous host). These results suggest that a pSBAC-driven heterologous expression strategy is an ideal approach for producing low and inconsistent Streptomyces NRPS-family NPs, such as daptomycin, which are produced low and inconsistent in native host.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.35.2-35.2
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• 2014

Today, it is widely accepted that dense environments tend to accelerate galaxy evolution. However, according to recent studies, the environments where galaxies evolve most considerably are galaxy groups rather than galaxy clusters. In an isolated group, the central host galaxy and its satellites co-evolve and interact with each other; as a result, they tend to have similar properties. Such conformity between host and satellite galaxies are relatively well known in galaxy groups, but it is hardly studied what happens after such galaxy groups merge into a galaxy cluster. Recently, J. H. Lee et al. (2014) have found that the colors of bright galaxies in WHL J085910.0+294957, a galaxy cluster at z = 0.3, show a measurable correlation with the mean colors of faint companions around them, which may be the vestige of infallen groups in the cluster. As a follow-up study, we explore more galaxy clusters, Abell 3659 and Abell 1146 at z ~ 0.1, using deep images obtained from the Magellan (Baade) 6.5-m telescope. Cluster members are selected based on the distributions of color, size and concentration along magnitude and spatial distribution. We investigate the dependence of the mean colors of faint companion galaxies on local environments and the properties of adjacent bright galaxies. After comparing the results with those in J. H. Lee et al. (2014), we discuss the origin of the relationships between bright galaxies and their faint companions based on their dependence on cluster properties.

• Journal of Korea Technology Innovation Society
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• v.14 no.2
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• pp.301-319
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• 2011

This research focused on the strategy consulting of the 'Pankyo Technovalley' for the formation of the innovation clusters The study was performed based on both theoretical study and related qualitative study approaches. Particularly, 'scenario planning' as a foresight method was used for the strategy formulation of the innovation clusters. The major determinants for the success of the formation of the innovation clusters can be summarized as follows; the enhancement of the service of the host institution of clusters, the alignment of the national cluster policy with the strategy of the host institution and the networks of the clusters. In terms of the needs of times, this study regarding the strategy for the formation of the innovation clusters is anticipated to be a good reference for the R&D organizations and technology cluster participants in coming years.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.60.1-60.1
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• 2016

To obtain a reliable estimate of the cold dark matter (CDM) substructure mass function in a dense cluster environment, one needs to understand how long a merged halo can survive within the host halo. Measuring disruption time scale of merged halos in a dense cluster environment, we attempt to construct the realistic CDM mass function that can be compared with stellar mass functions to get a stellar-to-halo mass ratio. For this, we performed a set of high-resolution simulations of cold dark matter halos with properties similar to the Virgo cluster. Field halos outside the main halo are detected using a Friend-of-Friend algorithm with a linking length of 0.02. To trace the sub-halo structures even after the merging with the main halo, we use their core structures that are defined to be the most 10% bound particles.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2004.10a
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• pp.65-67
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• 2004

During initial interactions of bacteria with their host plants, most plants recognize the bacterial infections and repel the pathogen by plant defense mechanism. The most active plant defense mechanism is the hypersensitive response (HR) which is the localized induced cell death in the plant at the site of infection by a pathogen. A primary locus induced in gram-negative phytopathogenic bacteria during this initial interaction is the Hrp locus. The Hrp locus is composed of a cluster of genes that encodes the bacteral Type 111 machinery that is involved in the secretion and translocation of effector proteins to the plant cell. DNA sequence analysis of hrp gene in phytopathogenic bacteria has revealed a Hrp pathogenicity is]and (PAI) with a tripartite mosaic structure. For many gram-negative pathogenic bacteria, colonization of the host's tissue depends on the type III protein secretion system (TTSS) which secrets and translocates effector proteins into the host cell. Effectors can be divided into several groups including broad host range effectors, host specific effectors, disease specific effectors, and effectors inhibit host defenses. The role of effectors carrying LRR domain in plant resistance is very elusive since most known plant resistance gene carry LRR domain. Host specific effectors such as several avr gene products are involved in the determination of the host specificity. Almost all the phytopathogenic Xanthomonas spp. carry avrBs1, avrBs2, and avrBs3 homologs. Some strains of X. oryzae pv. oryzae carry more than 10 copies of avrBs3 homologs. However, the functions of all those avr genes in host specificity are not characterized well.;

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2110-2116
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• 2012

This research focused on the strategy formulation for the development of the innovation cluster in Gyeonggi Province - 'Pankyo & Gwanggyo Technovalley'. The study was performed based on both theoretical study and quantitative & qualitative study approaches. Particularly, questionnaire survey was used for the diagnosis of the developmental stages of the innovation clusters. The major determinants for the development of the innovation cluster in Gyeonggi Province can be summarized as follows; the establishment of S&T based host institution, the gradual enlargement of the role of host institution and the enhancement of the network capability of innovation clusters. In terms of the needs of times, this study regarding the strategy for the development of the innovation clusters is anticipated to be a good reference for the R&D organizations and technology cluster participants in coming years.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4C
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• pp.433-441
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• 2003

We propose a new resource reservation scheme called MC-HMRSVP(Mobile clustering based-Hierarchical mobile ReSource reserVation Protcol) that is an extension of HMRSVP[3,4]. MC-HMRSVP always establishes a virtual cluster called Mobile Cluster, which includes its immediately adjacent MA(Mobile Agent) for passive reservation as well as the current MA for active reservation to which MH(Mobile Host) belongs. Our scheme also establishes the MC regardless of intra/inter region movement by GMA(Gateway Mobile Agent) function when a MH moves. To provide a general formulation on analyzing the performance in terms of reservation cost, we also model the resource reservation cost by using a simple recursive equation. Then, we show that our scheme decreases the reservation cost in comparison with the existing HMRSVP extentions.