• Journal of Microbiology and Biotechnology
• /
• v.23 no.11
• /
• pp.1560-1568
• /
• 2013

Salmonella, a main cause of foodborne diseases, encounters a variety of environmental stresses and overcomes the stresses by multiple resistance strategies. One of the general responses to hyperosmotic stress is to import or produce compatible solutes so that cells maintain fluid balance and protect proteins and lipids from denaturation. The ProP and ProU systems are the main transport systems for compatible solutes. The OsmU system, recently identified as a third osmoprotectant transport system, debilitates excessive growth as well by reducing production of trehalose. We studied a fourth putative osmoprotectant transport system, YehZYXW, with high sequence similarity with the OsmU system. A Salmonella strain lacking YehZ, a predicted substrate-binding protein, did not suffer from hyperosmolarity but rather grew more rapidly than the wild type regardless of glycine betaine, an osmoprotectant, suggesting that the YehZYXW system controls bacterial growth irrespective of transporting glycine betaine. However, the growth advantage of ${\Delta}yehZ$ was not attributable to an increase in OtsBA-mediated trehalose production, which is responsible for the outcompetition of the ${\Delta}osmU$ strain. Overexpressed YehZ in trans was capable of deaccelerating bacterial growth vice versa, supporting a role of YehZ in dampening growth. The expression of yehZ was increased in response to nutrient starvation, acidic pH, and the presence of glycine betaine under hyperosmotic stress. Identifying substrates for YehZ will help decipher the role of the YehZYXW system in regulating bacterial growth in response to environmental cues.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.764-767
• /
• 2003

The characteristics of diesel spray have much effect on the engine performances such as power. fuel consumption rate and emissions. Therefore, the measurement of fuel spray characteristics is very important for the improvement of heat engine. The factors which control diesel spray characteristics are injection pressure, ambient temperature and density etc. Spray behaviors are visualized by using the high speed video camera and spray angle, spray penetration are measured. Experimental equations of spray penetration and spray angle were derived by using the experimental results. 1) Ambient temperature and density influence on the characteristics of diesel spray. 2) Experimental equation of spray penetration is expressed as follows 0＜t＜ $t_{b}$ ; $S_1$=11.628$\Delta$ $P^{0.485}$ $\rho$$_{a}$ $^{-0.478}$ $t^{1.337}$, $t_{b}$ ＜t; $S_2$=7.457$\Delta$ $P^{0.523}$ $\rho$$_{a}$ $^{-0.382}$ $t^{0.548}$ 3) Experimental equation of spray Angie is expressed as follows $T_{a}$ =293K; Tan($\theta$/2)=059($\rho$$_{a}$ / $\rho$$_{f}$ )$^{0.437}$, $T_{a}$ =473K; Tan($\theta$/2)=0588($\rho$$_{a}$ / $\rho$$_{f}$ )$^{0.404}$_{f}$ )$^{0.404}$

• The Plant Pathology Journal
• /
• v.24 no.3
• /
• pp.289-295
• /
• 2008

RNA-RNA interactions and the dynamic RNA conformations are important regulators in virus replication in several RNA virus systems and may also involved in the regulation of many important virus life cycle phases, including translation, replication, assembly, and switches in these important stages. The 5' non-translated region of Potato virus X(PVX) contains multiple cis-acting elements that facilitate various viral processes. It has previously been proposed that RNA-RNA interactions between various RNA elements present in PVX RNA genome are required for PVX RNA accumulation(Hu et al., 2007; Kim and Hemenway, 1999). This model was based on the potential base-pairing between conserved sequence elements at the upstream of subgenomic RNAs(sgRNAs) and at the 5' and 3' end of RNA genome. We now provide more evidence that RNA-RNA base-pairing between elements present at the 5' end and upstream of each sgRNA is required for efficient replication of genomic and subgenomic plus-strand RNA accumulation. Site-directed mutations introduced at the 5' end of plus-strand RNA replication defective mutant(${\Delta}12$) increasing base-pairing possibility with conserved sequence elements located upstream of each sgRNAs restored genomic and subgenomic plus-strand RNA accumulation and caused symptom development in inoculated Nicotiana benthamiana plants. Serial passage of a deletion mutant(${\Delta}8$) caused more severe symptoms and restored wild type sequences and thus retained possible RNA-RNA base-pairing. Altogether, these results indicate that the RNA element located at the 5' end of PVX genome involved in RNA-RNA interactions and play a key role in high-level accumulation of plus-strand RNA in vivo.

• Korean Journal of Microbiology
• /
• v.46 no.4
• /
• pp.389-396
• /
• 2010

Insecticidal crystalline toxin producing Bacillus thuringiensis BT17 strain was isolated and identified as B. thuringiensis serovar colmeri by 16S rRNA analysis. BT17 strain produced crystalline ${\delta}$-endotoxin against to Lepidopteran larvae effectively on the culture broth of soybean meal and skim milk, $30^{\circ}C$ and 36 h shaking culture of 280 rpm. The maximum colony forming unit achieved when the culture was continued for 24 h, but the number of crystals increased until 36 h in the 200 L fermentor. Liquid type of biological insecticide product was made, and after 3 months storage in $20^{\circ}C$ the number of crystals was increased up to twice than beginning. Biocontrol effect of BT17 insecticide product was better in Plutella xylostella than in Spodoptera exigua, and the toxicity to animals was negligible.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.12
• /
• pp.1671-1683
• /
• 2016

Locally repairable codes (LRCs) constitute an important class of codes for distributed storage, where repair efficiency is a key metric of system performance. In LRCs, efficient repair is achieved by small locality-number of nodes participating in the repair process. In this paper, we focus on situations where different locality is required for different nodes. We present a non-trivial extension of the recent results on multiple (or unequal) localities to the $r,{\delta}$-locality case. A new Singleton-type minimum distance upper bound is derived and an optimal code construction is provided. While the result is limited to the case of only two different localities, it should be noted that it can be directly applied to the more general case where the localities are specified not exactly but by upper limits.

• Korean Journal of Microbiology
• /
• v.37 no.2
• /
• pp.137-144
• /
• 2001

In order to investigate the diversity of bacterial community in the mud flat of Sunchon Bay, Chunnam province, diversity of amplified 16S rDNA was examined. Total DNA was extracted from sediment soils and 16S rDNAs were amplified using PCR primers based on the universally conserved sequences in bacteria. Clonal libraries were constructed and 111 clones were examined by amplified rDNA restriction analysis (ARDRA) using HaeIII. Clones were clustered based on restriction patterns using computer program, GelCompar II. One hundred different RFLP types were detected from 111 clones. The 20 clones were selected and sequenced according to dendrograms derived from ARDRA, to cover most of the bacterial diversity in the clone libraries. None of the clones were identical to any representatives in the Ribosomal Database Project small subunit RNA databases and GenBank. All sequences showed between 77 and 96.8% similarity to the known 16s rRNA sequence from cultured organisms. The 20 clones sequenced fell into seven major lineages of the domain Bacteria: alpha-, delta-, gamma-Proteobacteria, low G+C Gram positive bacteria, high G+C Gram positive bacteria, Sphingobacteria (Cytophaga) and Cyanobacteria (chloroplast). Among the clones, the Proteobacteria were dominant.

• Economic and Environmental Geology
• /
• v.26 no.1
• /
• pp.55-65
• /
• 1993

Udo Island, some 3 km off the coast of Sungsan Peninsula at the eastern promontory of Cheju Island, occurs in such a regular pattern on the sequences which reprent an excellent example of an eruptive cycle. The island comprises a horseshoe-shaped tuff cone, a nested cinder cone on the crater floor, and a lava delta which extends over northwest from the moat between two cones. The volcanic sequences suggest volcanic processes that start with emergent Surtseyan eruption, progress through Strombolian eruption and end with lava effusion followed by reworking of smooth tephra on the tuff cone. Eruptive environment and hydrology of vent area in the Udo tuff cone are poorly constrained because the stratigraphic units under the tuff cone are unknown. It is thoughl, however, that the tuff cone could be mainly emergent because the present cone deposits show no evidence of marine reworking, and standing body of sea water could play a great role. The emergent volcano is characterized by distinctive steam-explosivity that results primarily from a bulk interaction between rapidly ascending magma and a highly mobile slurry. The sea water gets into the vent by flooding accross or through the top or breach of tephra cone. Udo tuff cone was constructed from Surtseyan eruption which went into with tephra finger jetting activities in the early stage, late interspersed with continuous uprush activities and proceeded to only continuous uprush activities in the last. When the enclosure of the vent by a long-lived tephra barrier would prevent the flooding and thus allow the vent to dry out, the Surtseyan eruption ceased to transmit into Strombolian activities, which constructed a cinder cone on the crater floor of the tuff cone. The Strombolian eruption ceased when magma in the conduit gradually became depleted in gas. In the case of Udo, the last magmatic activity was Hawaiian-type (and/or fountain) which accumulated basalt lava delta. And then the loose tephra of the tuff cone reworked over the moat lava and the northeastern flank.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.2
• /
• pp.313-321
• /
• 2000

This paper deals with a kind of the half-space interfacial problem in time domain, requiring the calculation of the horizontal electric field generated by a tiny impulsive current source located horizontally at the interface between an isotropic upper half-space and a uniaxially anisotropic lower half-space. With the Cagniard-de-Hoop method adapted for our interfacial case, we obtain the explicit-form solution for this electric field. We also investigate the impulse radiation in the radial direction. The impulse components of Dirac $\delta$-function type in transient waveforms are important for the understanding of the interfacial far-field characteristics. The uniaxial case is a generalization of the isotropic one, and the explicit solutions of the uniaxial problem in this paper reduce to the solutions of the isotropic problem if the anisotropy is removed.

• Journal of the Society of Naval Architects of Korea
• /
• v.33 no.4
• /
• pp.60-65
• /
• 1996

Mathematical model of maneuvering motion for a single-screw single-rudder ship established and versatile applications to the special situations of maneuvering are attempted. While, the mathematical model for twin-screw twin-rudder ship is not presented so much, because that type of ship is not popular. Lee et al. have examined the characteristics of such ship by captive model tests in 1988. This paper treats new mathematical models for propeller effective wake ($1-w_p$) and effective neutral rudder angle ${\delta}_R$ in the case of twin-screw twin-rudder ship. And some maneuvering motions are calculated with proposed models and compared with exact simulations.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1112-1113
• /
• 2006

The perovskite- type oxide $(ABO_3)$ containing transition metals on the B-site show mixed (electronic/ionic) conductivity. These mixed-conductivity oxides are promising materials for oxygen permeating membranes. The main objective of this research work is to synthesize and characterization ceramic powders of the Sr-Co-Fe-O system for methane conversion using membrane reactor. SCFO powders were synthesized from the route was based on the complex method of combination of acid EDTA and citrate and shown be available by control efficient of synthesis to performed $SrCo_{0.8}Fe_{0.2}O_{3-\delta$, moreover, it presented easy implementation, reproducibility and operation. Powder ceramic was characterized by XRD, microscopic optic, SEM and TG-DTA.