• Journal of Microbiology and Biotechnology
• /
• v.8 no.6
• /
• pp.560-567
• /
• 1998

We have found that Thermoactinomyces vulgaris KFB-Cl00 produces a chitinase. The optimum temperature and pH of the enzyme activity were $55^{\circ}C$ and 6.5. The enzyme was stable after heat treatment at $80^{\circ}C$ for 30 min and stable in acidic and basic conditions (PH 6.0~11.0). The thermostable endo-chitinase from Thermoactinomyces vulgaris KFB-C100 was cloned into the plasmid pBR322 by using E. coli DH5$\alpha$ as a host strain. The positive clone carrying a recombinant plasmid (PKCHI23) with a 4.1-kb fragment containing the chitinase gene was found. The recombinant plasmid was analyzed to determine the essential region for chitinase activity and obtained a 2.3-kb fragment, which was sub cloned into pTrc99A using the PstI and SalI sites to construct pTrc99A/pKCHI23-3. The resulting plasmid exerted high chitinase activity upon transformation of E. coli XL1-Blue cells. Chitinase was overproduced 14 times more in the clone cells than in the wild-type cells and the enzyme was purified to homogeneity. The purified enzyme showed the similar properties as the native chitinase from T. vulgaris in terms of molecular weight and substrate specificity. The catalytic action of the cloned enzyme was an endo type, producing chitobiose as a major reaction product.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.6
• /
• pp.828-836
• /
• 2015

Based on its α-amylase activity at pH 5.0 and optimal pH of the crude enzyme, a strain (named B-5) with acid α-amylase production was screened. The B-5 strain was identified as Bacillus amyloliquefaciens through morphological, physiological, and biochemical characteristics analysis, as well as 16S rDNA phylogenetic analysis. Its α-amylase gene of GenBank Accession No. GU318401 was cloned and expressed in Escherichia coli. The purified recombinant α-amylase AMY-Ba showed the optimal pH of 5.0, and was stable at a pH range of 4.0-6.0. When hydrolyzing soluble starch, amylose, and amylopectin, AMY-Ba released glucose and maltose as major end products. The α-amylase AMY-Ba in this work was different from the well-investigated J01542-type α-amylase which also came from B. amyloliquefaciens. AMY-Ba exhibited notable adsorption and hydrolysis ability towards various raw starches. Structure analysis of AMY-Ba suggested the presence of a new starch-binding domain at its C-terminal region.

• Korean Journal of Medicinal Crop Science
• /
• v.28 no.1
• /
• pp.47-55
• /
• 2020

Background: Curcuma longa L., a perennial crop originating from tropical and subtropical region, including India, is noted for its important medicinal properties. However, C. longa plants are unable to endure the winter season in Korea, and its rhizomes were invariably succumb to fungal infection when stored in polyvinyl bags. In this study, we accordingly sought to develop a C. longa variety capable of producing high rhizome yields and to identify stable conditions under which rhizomes can be stored in Korea. Methods and Results: We evaluated the agronomic characteristics of nine C. longa germplasms and examined the effects of storing rhizomes at different temperatures (4℃ to 24℃) in paper bags or plastic baskets. We found that the finger rhizomes was higher in CUR02, CUR03, and CUR06 germplasms than those of other groups. Furthermore, in terms of yield per 1 ㎡, the weights of the finger rhizomes and tuberous roots were significantly higher in CUR09 (3.4 ㎏/㎡) and CUR04 (678.7 g/㎡) than those of other groups. Therefore, we consider that these C. longa germplasms might be useful as breeding material. Although the fresh weights of the rhizomes were slightly reduced when stored in paper bags and a plastic baskets at 10℃ to 15℃, there was no evidence of fungal decomposition or sprouting, which is observed when using a conventional storage method. Conclusions: The results of this study indicate that the selected C. longa germplasms can provide a useful source of breeding material for the development of high yielding varieties and that a temperature ranging from 10℃ to 15℃ and the use of paper bags or plastic baskets provide stable post-harvest storage conditions for C. longa rhizomes.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.48 no.6
• /
• pp.25-34
• /
• 2011

In this paper, In this paper, we propose a Cooperative Routing Protocol (CooRP) for supporting network convergence and transmission services efficiently in mobile ad-hoc wireless sensor networks with Rayleigh fading environments. The main contributions and features of this paper are as follows. First, the routing routes are decided on route stability based on entropy concepts using mobility of nodes within the direction guided line region to increase the operational lifetime of routes as well as reduce control overhead for route construction. Second, a cooperative data transmission strategy based on the constructed stable routing route is used to increase packet delivery ratio with advanced SNR. Third, a theoretical analysis for cooperative data transmission of the proposed CooRP with outage probability is presented. The performance evaluation of the proposed CooRP is performed via simulation using OPNET and analysis. The results of performance evaluation show that the proposed CooRP by using stable routing routes and cooperative transmission can increase packet delivery ratio efficiently.

• Industry Promotion Research
• /
• v.5 no.1
• /
• pp.13-20
• /
• 2020

This study is about consumer preference of plastic toilets that can provide automatic supply of recycled water. First, the preference for plastic toilet seat design by gender and age group was preferred for gender type C and G for the sex. As the result of the chi-square test, the significance probability is .044 and the significance is P <.0 5. I could confirm that. Age, teens, 40 s, and 50 s or older prefer type C, 20 s and 30 s, but B type is not statistically significant. Second, the differences among the groups of preference for appearance design criteria according to general characteristics were all stable (stable appearance) in gender, age, region, education, and salary, but the chi-square test showed that they were not statistically significant. There was no difference between them. This study has implications for improving competitiveness and productivity by reducing the main production cost by commercializing toilets made of plastic materials.

• Journal of Ecology and Environment
• /
• v.36 no.3
• /
• pp.183-191
• /
• 2013

Dissolved organic carbon (DOC) concentrations and zooplankton and particulate organic matter (POM) ${\delta}^{13}C$ values were measured in five reservoirs in Korea. Zooplankton ${\delta}^{13}C$ and POM ${\delta}^{13}C$ showed large range from -33‰ to -22‰ and a significant difference among the reservoirs. One eutrophic reservoir, Lake Masan, showed unique characteristics with the highest zooplankton density, the highest ${\delta}^{13}C$, and the highest DOC. Zooplankton ${\delta}^{13}C$ was similar to POM ${\delta}^{13}C$, implying that zooplankton occupies substantial portion of POM or that zooplankton isotopic composition is related to selective grazing and assimilation of food sources from bulk POM. Except Lake Masan zooplankton ${\delta}^{13}C$ values were negatively correlated to DOC concentration in four reservoirs with mostly forest land use. This pattern can be probably attributed to intensive agricultural land use in the watershed of Lake Masan compared to the mostly forest land use in the other watersheds. Understanding the relationship between zooplankton ${\delta}^{13}C$ values and the origin of organic matter associated with watershed characteristics will be valuable to better understand trophic relationships in reservoirs in the summer monsoon region.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.15 no.3
• /
• pp.55-66
• /
• 2012

This study was carried out to investigate vegetation of Rhododendron mucronulatum habitat in Mt. Biseul to recommend basic information for synecological characteristics and management methods. The survey was carried out from May to July, 2011 and totally 46 vegetation data including 42 families 93 genera 108 species 16 varieties and 5 forma were collected and analyzed. Among the investigated 129 taxa, the numbers of rare plant resources were summarized as 19 taxa; The rare plants designated by Korea Forest Service, the specific plants by floristic region and the endemic plants were listed as 3 taxa, 15 taxa and 4 taxa, respectively. Rhododendron mucronulatum habitat of Mt. Biseul was classified into 3 plant communities (Carex lanceolata-Rhododendron mucronulatum community, Potentilla dickinsii-Selaginella rossii community, Carex lanceolata-Quercus mongolica community). Carex lanceolata-Rhododendron mucronulatum community was subdivided into Tripterygium regelii subunit and Miscanthus sinensis for. purpurascens subunit by human interference degree. And synecology, syndynamics, synchorology of these plant communities were identified, and Site-species ordination analysis by Principal Coordinate Analysis (PCoA) reflected that human impact, soil moisture condition were main ecological factors determining the distribution pattern of classified plant communities. Therefore these plant communities correspond to quite distinctive 4 habitat types : unstable-dry type=Miscanthus sinensis for. purpurascens subunit, unstable-moderate type=Tripterygium regelii subunit, stable-dry type=Potentilla dickinsii-Selaginella rossii community, stable-moderate type=Carex lanceolata-Quercus mongolica community. Finally, through the vegetational diagnosis, proper management methods such as a limit on the access of visitors, planting of native woody plants after removing unwanted vines or grass were suggested.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 2000.04a
• /
• pp.53-60
• /
• 2000

Strain BH5 was isolated from naturally fermented Kimchi and identified as a bacteriocin producer, which has bactericidal activity against Micrococcus flavus ATCC 10240. Strain BH5 was identified tentatively as Lactococcus lactis by the API test and some characteristics. Lactococcus lactis BH5 showed a broad spectrum of activity against most of the non-pathogenic and pathogenic microorganisms tested by the modified deferred method. The activity of lacticin BH5, named tentatively as the bacteriocin produced by Lactococcus lactis BH5, was detected at the mid-log growth phase, reached its maximum during the early stationary phase, and decreased after the late stationary phase. Lacticin BH5 also showed a relatively broad spectrum of activity against non-pathogenic and pathogenic microorganisms as tested by the spot-on-lawn method. Its antimicrobial activity on sensitive indicator cells was completely disappeared by protease XIV or ${\alpha}$-chymotrypsin. The inhibitory activities of lacticin BH5 were detected during treatments up to 100$^{\circ}C$ for 30 min. Lacticin BH5 was very stable over a pH range of 2.0 to 9.0 and was stable with all the organic solvents examined. The cell concentration and bacteriocin production in strain BH5 were maximum when grown at 30$^{\circ}C$ in a modified MRS medium supplemented with 0.5% tryptone, 1.0% yeast extract, and 0.5% beef extract as nitrogen sources. It demonstrated a typical bactericidal mode of inhibition against Micrococcus flavus ATCC 10240. Lacticin BH5 was purified through ammonium sulfate precipitation, ethanol precipitation, and CM-Sepharose column chromatography. The apparent molecular mass of lacticin BH5 was estimated to be in the region of 3.7 kDa, by the direct detection of bactericidal activity after SDS-PAGE. Mutant strain NO141 which was isolated by nitrosoguanidine mutagenesis produced about 4 fold more bacteriocin than the wild type.

• Transactions of the Korean hydrogen and new energy society
• /
• v.19 no.5
• /
• pp.403-409
• /
• 2008

Polymer electrolyte membrane fuel cell (PEMFC) is very interesting power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, improvement of performance, effect of temperature and initial start at low temperature. These problems can be approached to be solved by using experiment and mathematical method which are general principles for analysis and optimization of control system for heat and hydrogen detecting management. In this paper, insulation vessel and control system for stable operation of fuel cell at low temperature were developed for experiment. The constant temperature capability and the heating time at sub-zero temperatures with insulation control system were studied by using a heating bar of 60W class. PEMFC stack which was made by 4 cells with $50\;mc^2$ active area in each cell is a thermal source. Times which take to reach constant temperature by the state of insulation vacuum were measured at variable environment temperatures. The test was performed at two conditions: heating mode and cooling mode. Constant temperature capability was better at lower environment temperature and vacuum pressure. The results of this experiment could be used as basis data about stable operation of fuel cell stack in low temperature zone.

• Journal of Communications and Networks
• /
• v.14 no.2
• /
• pp.162-168
• /
• 2012

This paper considers the scenario in which a set of nodes share a common channel. Some nodes have a rechargeable battery and the others are plugged to a reliable power supply and, thus, have no energy limitations. We consider two source-destination pairs and apply the concept of cognitive radio communication in sharing the common channel. Specifically, we give high-priority to the energy-constrained source-destination pair, i.e., primary pair, and low-priority to the pair which is free from such constraint, i.e., secondary pair. In contrast to the traditional notion of cognitive radio, in which the secondary transmitter is required to relinquish the channel as soon as the primary is detected, the secondary transmitter not only utilizes the idle slots of primary pair but also transmits along with the primary transmitter with probability p. This is possible because we consider the general multi-packet reception model. Given the requirement on the primary pair's throughput, the probability p is chosen to maximize the secondary pair's throughput. To this end, we obtain two-dimensional maximum stable throughput region which describes the theoretical limit on rates that we can push into the network while maintaining the queues in the network to be stable. The result is obtained for both cases in which the capacity of the battery at the primary node is infinite and also finite.