• Korean Journal of Microbiology
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• v.52 no.4
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• pp.391-397
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• 2016

Clostridium is a genus of Gram-positive, rod shape, spore-forming obligate anaerobe. Recently, Clostridium has been attracted as a host for bio-based chemical production, due to its diversity of substrate utilization and the production ability for metabolites which can be used as a building block for chemical production. Especially, butanol produced from Clostridium has been considered as an alternative fuel. As a transportation fuel, butanol has a higher energy density and lower hygroscopicity compared to ethanol, the first generation biofuel. Recently, metabolic engineering of Clostridium has been massively conducted for butanol production. In this study, the metabolic engineering strategy of Clostridium for butanol production has been reviewed with a brief perspective.

• The Journal of the Petrological Society of Korea
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• v.19 no.4
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• pp.255-267
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• 2010

The primary utilization of recently improved (U-Th)/He thermochronometry is to reveal the low-T thermal histories of shallow crustal sections or transient episodes (such as wildfires or meteorite impacts) because of the high sensitivity of He diffusion to temperature in host minerals. In this contribution, we present reviews and perspectives regarding how this method can be used to characterize the ejection-related shock metamorphism of Martian meteorites. The temperature conditions of shock metamorphism can be constrained through shock recovery experiments, paleomagnetism, and $^{40}Ar/^{39}Ar$ and (U-Th)/He dating. The most reliable constraints can be deduced when these independent approaches are combined. However, the thermal history of the ALH84001 Martian meteorite has been under serious debate because the different methods have yielded contrasting results. Recent work has shown how single-grain (U-Th)/He and $^{40}Ar/^{39}Ar$ dating, two noble-gas based thermochronometries with different T sensitivities, can be used to resolve this issue, providing a good example for future research on other meteorites.

• Research in Plant Disease
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• v.12 no.3
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• pp.189-196
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• 2006

Crown gall on lower stem of weeping fig(Ficus benjamina Roxb.) was first observed at Daejon in 2003. Tumors were about 15 cm in size and semi-round with rough surface texture of dark brown color. Two virulent isolates among ten bacteria isolated from the tumor tissues were characterized. Their colonies were convex, glistening, circular with an entire edge, and white or tannish cream in color on potato dextrose agar supplemented with 0.5% $CaCO_3$. They were rod shape with peritrichous flagellae, gram-negative, aerobic growth, oxidase-positive, and grew on D1M agar. The isolates were identified as Agrobacterium larrymoorei and A. tumefaciens based on biochemical and physiological characteristics, fatty acid profiles and substrate utilization patterns. Seedlings of some host plants excepting grapevine produced typical galls two to three weeks after inoculation with cell suspensions of the virulent strains. This is the first report on crown gall of weeping fig in Korea.

• Research in Plant Disease
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• v.12 no.3
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• pp.197-204
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• 2006

Crown gall on lower stem and root of chrysanthemum(Dendranthema grandiflorum Kitamura) was observed at Hwasung and Gumi in 2001 and 2004, respectively. Tumors were semi-round with rough surface texture of dark brown color. Nine isolates inducing gall formation on lower stem of chrysanthemum among twenty isolates from the tumor tissues were characterized. Their colonies were convex, glistening, circular with an entire edge and whitish or tannish cream in color on potato dextrose agar supplemented with 0.5% $CaCO_3$. The virulent isolates were rod-shaped with peritrichous flagellae, gram negative, aerobic and growing on D1M agar. Among nine virulent isolates, one isolate was identified as Agrobacterium rubi and eight isolates were A. tumefaciens based on biochemical and physiological characteristics, fatty acid profiles and substrate utilization patterns. A. tumefaciens had strong pathogenicity and broad host range compared with A. rubi. This is the first report on crown gall of chrysanthemum in Korea. To our knowledge, crown gall of chrysanthemum caused by A. rubi is first report in this study worldwide.

• Journal of Microbiology and Biotechnology
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• v.22 no.4
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• pp.555-562
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• 2012

PCR was performed to analyze the ${\beta}$-lactamase genes carried by ampicillin-resistant Vibrio spp. strains isolated from marine environments in Korea between 2006 and 2009. All 36 strains tested showed negative results in PCR with the primers designed from the nucleotide sequences of various known ${\beta}$-lactamase genes. This prompted us to screen new ${\beta}$-lactamase genes. A novel ${\beta}$-lactamase gene was cloned from Vibrio alginolyticus KV3 isolated from the aquaculture water of Geoje Island of Korea. The determined nucleotide sequence (VAK-3 ${\beta}$-lactamase) revealed an open reading frame (ORF) of 852 bp, encoding a protein of 283 amino acids (aa), which displayed low homology to any other ${\beta}$-lactamase genes reported in public databases. The deduced 283 aa sequence of VAK-3, consisting of a 19 aa signal peptide and a 264 aa mature protein, contained highly conserved peptide segments specific to class A ${\beta}$-lactamases including the specific amino acid residues STFK (62-65), SDN (122-124), E (158), and RTG (226-228). Results from PCR performed with primers specific to the VAK-3 ${\beta}$-lactamase gene identified 3 of the 36 isolated strains as V. alginolyticus, Vibrio cholerae, and Photobacterium damselae subsp. damselae, indicating the utilization of various ${\beta}$-lactamase genes including unidentified ones in ampicillin-resistant Vibrio spp. strains from the marine environment. In a mating experiment, none of the isolates transfered the VAK-3 ${\beta}$-lactamase gene to the Escherichia coli recipient. This lack of mobility, and the presence of a chromosomal acyl-CoA flanking sequence upstream of the VAK-3 ${\beta}$-lactamase gene, led to the assumption that the location of this new ${\beta}$-lactamase gene was in the chromosome, rather than the mobile plasmid. Antibiotic susceptibility of VAK-3 ${\beta}$-lactamase was indicated by elevated levels of resistance to penicillins, but not to cephalosporins in the wild type and E. coli harboring recombinant plasmid pKV-3, compared with those of the host strain alone. Phylogenetic analysis showed that VAK-3 ${\beta}$-lactamase is a new and separate member of class A ${\beta}$-lactamases.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.1-14
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• 2002

The most important issue in providing multimedia traffic on a mobile computing environments is to guarantee the mobile host(client) with consistent QoS(Quality of Service). However, the QoS negotiated between the client and network in one cell may not be honored due to client mobility, causing hand-offs between cells. In this paper, a call admission control mechanism is proposed to provide consistent QoS guarantees for multimedia traffics in a mobile computing environment. Each cell can reserve fractional bandwidths for hand-off calls to its adjacent cells. It is important to determine the right amount of reserved bandwidth for hand-off calls because the blocking probability of new calls may increase if the amount of reserved bandwidth is more than necessary. An adaptive bandwidth reservation based on an MPP(Mobility Pattern Profile) and a 2-tier cell structure has been proposed to determine the amount of bandwidth to be reserved in the cell and to control dynamically its amount based on its network condition. We also propose a call admission control based on this bandwidth reservation and "next-cell prediction" scheme using an MPP. In order to evaluate the performance of our call admission control mechanism, we measure the metrics such as the blocking probability of our call admission control mechanism, we measure the metrics such as the blocking probability of new calls, dropping probability of hand-off calls, and bandwidth utilization. The simulation results show that the performance of our mechanism is superior to that of the existing mechanisms such as NR-CAT1, FR-CAT1, and AR-CAT1.

• KIISE Transactions on Computing Practices
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• v.22 no.8
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• pp.369-374
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• 2016

The growing demand of virtual computing and storage resources in the cloud computing environment has led to deduplication of storage system for effective reduction and utilization of storage space. In particular, large reduction in the storage space is made possible by preventing data with identical content as the virtual desktop images from being stored on the virtual desktop infrastructure. However, in order to provide reliable support of virtual desktop services, the storage system must address a variety of workloads by virtual desktop, such as performance overhead due to deduplication, periodic data I/O storms and frequent random I/O operations. In this paper, we designed and implemented a clustered file system to support virtual desktop and storage services in cloud computing environment. The proposed clustered file system provides low storage consumption by means of inline deduplication on virtual desktop images. In addition, it reduces performance overhead by deduplication process in the data server and not the virtual host on which virtual desktops are running.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.783-798
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• 2004

An e-business client application in ubiquitous mobile computing environment may become disconnected from the enterprise server due to broken communication connections caused by the limitation of mobile computing environments(limited battery life of the mobile device, low bandwidth communication, incomplete wireless communication infrastructure, etc). It Is even Possible that mobile client application Intentionally operates in disconnected mode to reduce communication cost and the power consumption of the mobile device. We use “data hoarding” as a means of providing local autonomy to allow transactions to be processed and committed on the mobile host despite of disconnection. The key problem to this approach is the synchronization problem that serialize potentially conflicting updates from disconnected clients on master objects of the server database. In this paper, we present a new transaction synchronizing method that splits a transaction into a set of independent component transactions and give the synchronization priority on each component taking the possibility of use and conflicts in the server into consideration. Synchronization is performed component by component based un synchronization priority. After the Preferred component of a no bile transaction succeeds in synchronization with the server, the mobile transaction can pre-commit at server. A pre-committed transaction's updated value is made visible at server before the final commit of the transaction. The synchronization of the component with low synchronization priority can be delayed in adaption to wireless bandwidth and computing resources. As a result, the availability of important data updated by mobile client is increased and it can maximize the utilization of the limited wireless bandwidth and computing resources.

• Korea Trade Review
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• v.42 no.1
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• pp.283-301
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• 2017

As a consequence of the changed role and functions in port operations, the role of port hinterland has transformed to multi-functional logistic centre linking more efficiently elements of the supply chain. This paper analysed distribution centre selection factors in Busan new port hinterland, aiming to diagnose and evaluate the operational situations of port hinterland as multi-functional logistics centre. Based on a data collected from all 122 samples located in Busan new port hinterland, determinants for location competitiveness identified were: political support, market potentiality, infrastructure utilization, market niche, and connectivity. Comparing the difference between an importance and performance, it is revealed that the target port hinterland requires urgent improvement in political supports such as incentive programmes offered by host country, free trade system and related law, financial assistance in constructing distribution centers, and simplicity, ease and efficiency of administrative procedures. The results provide useful insights for establishing future improvement strategies and a strategic agenda to successfully respond to the demands of the companies located in port hinterlands and/or new customers those who want to move in.