• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.213.3-213
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• 2005

• Proceedings of the Microbiological Society of Korea Conference
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• 2007.05a
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• pp.86-88
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• 2007

• Proceedings of the Zoological Society Korea Conference
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• 2000.10a
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• pp.262.1-262
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• 2000

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.281.1-281
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• 1999

No Abstract, See Full Text

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.934-939
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• 2007

Thrust vector control(TVC) is the method which generates the side force and moment by controlling the exhausting gas directly from the supersonic nozzle to change the trajectory of a missile quickly. In this paper, performance study on the tapered ramp tabs asymmetrically installed in the supersonic nozzle exhaust for the thurst vector control has been carried out using the supersonic cold flow system. To study the shock wave structure and location of the oblique shock wave produced by the ramp tab, the flow field visualization using the schlieren system is conducted. This paper provides the thrust spoilage, three directional forces and moments and distribution of surface pressure on the region enclosed by the tapered ramp tabs.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.54.1-54.1
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• 2011

Formation of self-gravitating gas clouds and hence stars in galaxies is a consequence of both thermal and dynamical evolution of a gaseous medium. Using hydrodynamics simulations including cooling and heating explicitly, we follow simultaneously thermal and dynamical evolution of galactic gas disks to study dynamics and structures of galactic spiral shocks with thermal instability and regulation of the star formation rates (SFRs). We first perform one-dimensional simulations in direction perpendicular to spiral arms. The multiphase gas flows across the arm soon achieve a quasi-steady state characterized by transitions from warm to cold phases at the shock and from cold to warm phases in the postshock expansion zone, producing a substantial fraction of intermediate-temperature gas. Next, we allow a vertical degree of freedom to model vertically stratified disks. The shock front experiences unsteady flapping motions, driving a significant amount of random gas motions, and self-gravity promotes formation of bound clouds inside spiral arms. Finally, we include the star formation feedback in both mechanical (due to supernova explosion) and radiative (due to FUV heating by young stars) forms in the absence of spiral arms. At saturation, gravitationally bound clouds form via thermal and gravitational instabilities, which are compensated by disruption via supernova explosions. We find that the FUV heating regulates the SFRs when gas surface density is low, confirming the prediction of the thermal and dynamical equilibrium model of Ostriker et al. (2010) for star formation regulation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.11
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• pp.519-526
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• 2005

This paper presents computer simulation results for developing new type of SF$_{6}$ Circuit Breaker in terms of cold gas flow after small current interruption. This cold gas flows down a nozzle into the chamber of a circuit breaker. There are many difficult problems in analyzing the gas flow due to complex geometry, moving boundary, shock wave and so on. When predicting the dielectric capability of a gas circuit breaker after interruption, the gas pressure and density distributions due to the cold gas must be considered in addition to the electrical field imposed across the gas. A self-coded computational fluid dynamics (CFD) program is used for the simulation of cold gas flow in order to evaluate the electrical field characteristic across open contacts and transient characteristics of insulations after small current interruption.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.35-41
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• 2009

Both the nozzle expansion ratio and the chamber pressure are simultaneously and continuously changed according to pintle movement, resulting in a different internal flow structure and flow separation characteristics. In this paper, the pintle position effect on nozzle flow structure and separation phenomena is analyzed by experimental-aided Computational Fluid Dynamic(CFD). Among the turbulent models for RANS(Reynold Averaged Navier Stokes) in Fluent, Spalart-Allmaras model is better agreement with the nozzle wall pressure distribution attained by cold-flow test than other models. And even if a conical nozzle is used, there is a shock structure similar to cap-shock pattern mainly occurred in contoured or shaped optimized nozzle because of internal shock generated from pintle tip flow separation.

• The Plant Pathology Journal
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• v.24 no.2
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• pp.131-142
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• 2008

Magnaporthe oryzae, the causal agent of the rice blast disease, poses a worldwide threat to stable rice production. The large-scale functional characterization of genes controlling the pathogenicity of M. oryzae is currently under way, but little is known about heat shock protein 40 (Hsp40) function in the rice blast fungus or any other filamentous plant pathogen. We identified 25 genes encoding putative Hsp40s in the genome of M. oryzae using a bioinformatic approach, which we designated M. oryzae heat shock protein forty (MHF 1-25). To elucidate the roles of these genes, we characterized the functions of MHF16 and MHF21, which encode type ill and type n Hsp40 proteins, respectively. MHF16 and MHF21 expression was not significantly induced by heat shock, but it was down-regulated by cold shock. Knockout mutants of these genes $({\Delta}$mhf16 and ${\Delta}$mhf21) were viable, but conidiation was severely reduced. Moreover, sectoring was observed in the ${\Delta}mhf16$ mutant when it was grown on oatmeal agar medium. Conidial germination, appressorium formation, and pathogenicity in rice were not significantly affected in the mutants. The defects in conidiation and colony morphology were fully complemented by reintroduction of wild type MHF16 and MHF21 alleles, respectively. These data indicate that MHF16 and MHF21 play important roles in conidiation in the rice blast fungus.

• Journal of Microbiology and Biotechnology
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• v.30 no.2
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• pp.259-270
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• 2020

Listeria monocytogenes is a gram-positive, facultative anaerobe food pathogen responsible for the listeriosis that mostly occurs during the low-temperature storage of a cold cut or dairy products. To understand the systemic response to a wide range of growth temperatures, L. monocytogenes were cultivated at a different temperature from 10℃ to 42℃, then whole cell proteomic analysis has been performed both exponential and stationary cells. The specific growth rate increased proportionally with the increase in growth temperature. The maximum growth rate was observed at 37℃ and was maintained at 42℃. Global protein expression profiles mainly depended on the growth temperatures showing similar clusters between exponential and stationary phases. Expressed proteins were categorized by their belonging metabolic systems and then, evaluated the change of expression level in regard to the growth temperature and stages. DnaK, GroEL, GroES, GrpE, and CspB, which were the heat&cold shock response proteins, increased their expression with increasing the growth temperatures. In particular, GroES and CspB were expressed more than 100-fold than at low temperatures during the exponential phase. Meanwhile, CspL, another cold shock protein, overexpressed at a low temperature then exponentially decreased its expression to 65-folds. Chemotaxis protein CheV and flagella proteins were highly expressed at low temperatures and stationary phases. Housekeeping proteins maintained their expression levels constant regardless of growth temperature or growth phases. Most of the growth related proteins, which include central carbon catabolic enzymes, were highly expressed at 30℃ then decreased sharply at high growth temperatures.