• Proceedings of the PSK Conference
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• 2001.04a
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• pp.105.2-105.2
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• 2001

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.108-114
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• 1998

Salmonella Pathgenicity Island 2 plays an important role in Salmonella pathogenicity, especially invasion into host cell. We have investigated the effect of various environmental factors, such as oxygen level, osmolarity, pH, carbon starvation and glycerol addition on the expression of SPI2. For this research, we constructed the reporter plasmids, in which the promoter-less lac operons are fused with the regulatory regions (including promoter) of ssaJ and ssaK, major genes in SPI2. The study using the reporters showed that low oxygen, low osmolarity, or weak alkali conditions increased the expression levels of ssaJ and ssaK and when these three conditions exist simultaneously, the expression levels of ssaJ and ssaK are the highest. However carbon starvation and glycerol addition did not affect the expression of ssaJ and ssaK. These environmental effects on the expression levels of ssaJ and ssaK are the same in three Salmonella typhimurium wild types, LT2, UK1, and SL1344. In addition, we confirmed that the mutation in hilA, a regulatory gene encoding a transcriptional activator of SPI1, had no effect on the expression of ssaJ and ssaK. Thus, these results strongly suggest that the expressions of SPI2 and SPI1 are regulated by different control systems.

• Korean journal of applied entomology
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• v.52 no.2
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• pp.109-113
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• 2013

A greenhouse soil infested with an obligate nematode parasitic bacterium, Pasteuria penetrans, was used to test the effect of temperatures on the endospore attachment to root-knot nematode, Meloidogyne arenaria, juveniles (J2). Freshly hatched J2s were inoculated to the soil in petri dish and incubated under different temperatures of $20^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$, and $35^{\circ}C$ for 7 days. The endospore attachment rates were 100% in all the temperatures, while the number of endospores attached per J2 was highest in $25^{\circ}C$ with 28.3 endospores/J2 followed by 20.2, 18.6, and 13.6 in $30^{\circ}C$, $20^{\circ}C$, and $35^{\circ}C$, respectively. When the soil was pre-treated under different temperatures before the J2 inoculation, the endospore attachment rates significantly decreased from 60% in room temperature to $25^{\circ}C$, 31.7, 8.3, 5.0, and 0% after the soil incubation in $-30^{\circ}C$, $4^{\circ}C$, $40^{\circ}C$, $50^{\circ}C$, and $100^{\circ}C$ for 10 days, respectively. The endospore numbers attached per J2 were 3.5, 4.3, 1, 1, and 0 when the soil was pre-treated in $-30^{\circ}C$, $4^{\circ}C$, $40^{\circ}C$, $50^{\circ}C$, and $100^{\circ}C$, respectively, which were lower than 5.3/J2 of room temperature treated soil. The P. penetrans isolate in the soil showed nematode species-specific endospore attachment characteristics with 100% attachment rate only on M. arenaria J2s while the rates were 0% on M. hapla and M. incognita J2s.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.68.2-68.2
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• 2008

• Proceedings of the PSK Conference
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• 2000.04a
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• pp.189.2-189.2
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• 2000

• Proceedings of the PSK Conference
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• 2001.10a
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• pp.253.2-253.2
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• 2001

• Bulletin of the Korean Mathematical Society
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• v.29 no.2
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• pp.237-243
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• 1992

Let (M, g, J) be a closed Kahler manifold of complex dimension m > 1. We denote by Spec(M,g) the spectrum of the real Laplace-Beltrami operator. DELTA. acting on functions on M. The following characterization problem on the spectral rigidity of the complex projective space (CP$^{m}$ , g$_{0}$ , J$_{0}$ ) with the standard complex structure J$_{0}$ and the Fubini-Study metric g$_{0}$ has been attacked by many mathematicians : if (M,g,J) and (CP$^{m}$ ,g$_{0}$ ,J$_{0}$ ) are isospectral then is it true that (M,g,J) is holomorphically isometric to (CP$^{m}$ ,g$_{0}$ ,J$_{0}$ )\ulcorner In [BGM], [LB], it is proved that if (M,J) is (CP$^{m}$ , J$_{0}$ ) then the answer to the problem is affirmative. Tanno ([Ta]) has proved that the answer is affirmative if m .leq. 6. Recently, Wu([Wu]) has showed in a more general sense that if (M, g) and (CP$^{m}$ ,g$_{0}$ ) are (-4/m)-isospectral, m .geq. 4, and if the second betti number b$_{2}$(M) is equal to b$_{2}$(CP$^{m}$ ).

• Progress in Superconductivity and Cryogenics
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• v.18 no.4
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• pp.15-20
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• 2016

The effects of electron beam (EB) irradiation on the superconducting critical temperature ($T_c$) and critical current density ($J_c$) of YBCO films were studied. The YBCO thin films were irradiated using a KAERI EB accelerator with an energy of 0.2 MeV and a dose of $10^{15}-10^{16}e/cm^2$. A small $T_c$ decrease and a broad superconducting transition were observed as the EB dose increased. The value of $J_cs$ (at 20 K, 50 K and 70 K) increased at doses of $7.5{\times}10^{15}$ and $2.2{\times}10^{16}e/cm^2$. However, $J_cs$ decreased as the dose increased further. The X-ray diffraction (XRD) analysis showed that the c axis of YBCO was elongated and the full width at half maximum (FWHM) increased as the dose increased, which is strong evidence of the atomic displacement by EB irradiation. The transmission electron microscopy (TEM) showed that the amorphous layer formed in the vicinity of the surfaces of the irradiated films. The amorphous phase was often present as an isolated form in the interior of the films. In addition to the formation of the amorphous phase, many striations running along the a-b direction of YBCO were observed. The high magnification lattice image showed that the striations were stacking faults. The enhancement of $J_c$ by EB irradiation is likely to be due to the lattice distortion and the formation of defects such as vacancies and stacking faults. The decrease in $J_c$ at a high EB dose is attributed to the extension of the amorphous region of a non-superconducting phase.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.51.1-51.1
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• 2013

We present molecular line observations of a small group of Young Stellar Objects (YSOs), L1251C. Observations by Spitzer Space Telescope legacy program "From Molecular Cores to Planet Forming Disks"(c2d; Evans et al. 2003) revealed that there are three YSOs within ~15" in L1251C: IRS1 (Class I), IRS2 (Class II), and IRS3 (Class II). In order to understand the molecular environment around these YSOs, we carried out the KVN single-dish observations in $HCO^+$ J=1-0, $H^{13}CO^+$ J=1-0, $N_2H^+$ J=1-0 and HCN J=1-0. CO J=1-0 was also mapped in L1251C with the TRAO 14m telescope. Integrated intensity maps of high density tracers such as $H^{13}CO^+$ J=1-0, $N_2H^+$ J=1-0 and HCN J=1-0 show similar emission distributions, whose peaks are off from the positions of YSOs. However, $HCO^+$ J=1-0, which is believed to trace both infall and outflow, presents its emission distribution different from those of other molecular transitions. The line profile of $HCO^+$ J=1-0 is superimposed by two velocity (narrow and broad) components. The $HCO^+$ outflow map reveals multiple structures while the CO outflow map elongates mainly along the EW direction. With the KVN single dish, the 22 GHz $H_2O$ maser emission has been also monitored toward L1251C to find variations of the systemic velocity and intensity with time.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.479-489
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• 1989

The $J_{k}$ integral method for determining mixed mode stress intensity factors separately in the cracked anisotropic plate is developed. Stress intensity factors are indirectly determined from the values of $J_{1}$ and $J_{2}$. The $J_{2}$ integral can be evaluated efficiently from a finite element solution, neglecting the contribution from the portion of the integration contour along the crack faces, by selecting the integration contour in the vicinity of the crack tip. Using functions of a complex variable, the complete relations between $J_{1}$, $J_{2}$ and $K_{I}$ , $K_{II}$ for anisotropic materials are derived conveniently by selecting narrow rectangular contours shrinking to the crack tip. Compared to the existing path independent integral methods, the present method does not involve calculating the auxiliary solution and hence numerical procedures become quite simple. Numerical results to various problems are given and demonstrate the accuracy, stability and versatility of the method.