• Korean Journal of Microbiology
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• v.4 no.2
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• pp.1-4
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• 1966

As a part of studies of plant tumor induction, this experiment was prepared for the purpose of studying the ability of tumor induction and the tendency of tumor initiation in some Korean plants using the various Agrobacterium tumefaciens strains. Results obtained from this experiment are as follows. The virulences of five strains used in this experiment were gradually decreased in order of strain A6Kl, B6, 11BV7, T37 and 11 BNV6. Especially strain T37 which is known to the host limited strain showed virulent effect to the most of plants given for the materials as well as strain A6Kl, B 6 and 11BV7. Concerning the grade of tumor development, in plants which has tough stem, for example, Glycine max Meer, tumor induction was not well developed after the inoculation of all strains. Particullary in Ricinus communes Linne all strains showed virulent effect but tumor tissues were declined in relation to the development of lignification. It was also confirmed that the induction of tumor tissues on plants is to delay according to the increase of the age of host plants.

• Electrical & Electronic Materials
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• v.10 no.10
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• pp.989-994
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• 1997

In a Guest-Host cell the orientational ordering of dyes doped into liquid crystals has been investigated. To evaluate the influence of the host liquid crystals on the ordering of the dyes we have measured precisely the ordering parameters of the liquid crystals by using the dichroic ratio of the absorbances for infrared light polarized parallel and perpendicular to the diector. Our experimental results show that the ordering of the dyes can be expressed as a function of not only the molecular structure of the dyes but also the order parameter of the liquid crystals. These functions are dependent on the kinds of the liquid crystals and the dyes. Particularly the combination such as anthraquinone dyes doped into cyanobiphenyl liquid crystals show a very high ordering parameter. This is considered due to a strong intermolecular interaction between the dipoles of both liquid crystals and dyes.

• Journal of The Korean Astronomical Society
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• v.55 no.2
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• pp.37-57
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• 2022

Using I-band images of 35 nearby (z < 0.1) type 1 active galactic nuclei (AGNs) obtained with Hubble Space Telescope, selected from the 70-month Swift-BAT X-ray source catalog, we investigate the photometric properties of the host galaxies. With a careful treatment of the point-spread function (PSF) model and imaging decomposition, we robustly measure the I-band brightness and the effective radius of bulges in our sample. Along with black hole (BH) mass estimates from single-epoch spectroscopic data, we present the relation between BH mass and I-band bulge luminosity (M_BH-M_I,bul relation) of our sample AGNs. We find that our sample lies offset from the M_BH-M_I,bul relation of inactive galaxies by 0.4 dex, i.e., at a given bulge luminosity, the BH mass of our sample is systematically smaller than that of inactive galaxies. We also demonstrate that the zero point offset in the M_BH-M_I,bul relation with respect to inactive galaxies is correlated with the Eddington ratio. Based on the Kormendy relation, we find that the mean surface brightness of ellipticals and classical bulges in our sample is comparable to that of normal galaxies, revealing that bulge brightness is not enhanced in our sample. As a result, we conclude that the deviation in the M_BH-M_I,bul relation from inactive galaxies is possibly because the scaling factor in the virial BH mass estimator depends on the Eddington ratio.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.146-153
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• 2007

A mathematical competition model between normal flora and an invading pathogen was devised to allow analysis of bacterial infections in a host. The normal flora includes the various microorganisms that live on or within the host and act as a primary human immune system. Despite the important role of the normal flora, no mathematical study has been undertaken on models of the interaction between it and invading pathogens against a background of antibiotic treatment. To quantify key elements of bacterial behavior in a host, pairs of nonlinear differential equations were used to describe three categories of human health conditions, namely, healthy, latent infection, and active infection. In addition, a cutoff value was proposed to represent the minimum population level required for survival. The recovery of normal flora after antibiotic treatment was also included in the simulation because of its relation to human health recovery. The significance of each simulation parameter for the bacterial growth model was investigated. The devised simulation showed that bacterial proliferation rate, carrying capacity, initial population levels, and competition intensity have a significant effect on bacterial behavior. Consequently, a model was established to describe competition between normal flora and an infiltrating pathogen. Unlike other population models, the recovery process described by the devised model can describe the human health recovery mechanism.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.33.1-33.1
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• 2010

We investigate the relation between the presence of bars in galaxies and AGN activities. Bars are believed to play an important role in fueling of AGN. Although there have been many previous studies on this topic, "the AGN-Bar Connection" is still an open question. To better understand the connection, we use a volume-limited sample of 9,726 late-type galaxies brighter than $M_r$=-19.5+5logh at $0.02{\leqq}z{\leqq}0.05489$, drawn from SDSS DR7. Among galaxies in the sample, 1,963 galaxies are classified as AGN-host galaxies based on the emission-line ratios while barred galaxies are identified by visual inspection. The bar fraction in AGN host galaxies (22.5%) is 3-times higher than in star-forming galaxies (8.6%). However, this trend is simply caused by the fact that the bar fraction increases with galaxy mass or luminosity and that AGN host galaxies are on average more massive than star-forming galaxies. Nevertheless, we find that among AGN host galaxies, the bar fraction increases with the Eddington ratio $(L_{[OIII]}/M_{[BH]})$, and this trend remains intact even at fixed galaxy luminosity and stellar velocity dispersion. These results imply that bars play a role in triggering AGNs.

• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.20-23
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• 2003

Low-sulfidation style ore deposits, the major source of Au, Ag, and Hg, are formed from neutral-pH, reduced hydrothermal solutions close to equilibrium with their host rocks. The waters are low-salinity (〈1 wt % NaCl equiv.) but relatively gas rich (1-2 wt % $CO_2$), and are largely meteoric water. However, the contribution of magmatic components to the epithermal system, its temporal importance, and its relation to the source of ore metals are largely controversial. (omitted)

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.36.1-36.1
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• 2021

Galaxy clusters host Mpc-scale diffuse radio emission giving us evidence of large-scale magnetic fields in the Universe. It is relevant to understand magnetic field amplification processes occurring at the center and outskirts of galaxy clusters. Each of these processes are believed to give rise to observed radio haloes and radio relics, respectively. In this work, we focus on studying the continuum and polarised emission in radio relics. We use threedimensional magnetohydrodynamical simulations of merger shock waves propagating through a magnetized, turbulent intracluster medium. Our model includes the diffusive shock acceleration (DSA) of cosmic ray electrons, their spatial advection and energy losses at run-time. We discuss the relation between the mock observation features and the underlying morphology of the magnetic field.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.58.3-58.3
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• 2015

Blue Straggler Stars (BSSs), kind of unusual main sequence stars, are the brighter and bluer stars than the main sequence turn off (MSTS) stars in coeval clusters. Since the first detection in globular clusters (GCs), BSSs have been shown to reveal an anti-correlation between the luminosity of their host star cluster and the number of BSSs in the cluster. Further, conclusions based on this result can be expanded to the open clusters. BSSs seem to play an important role in GCs according to the relation between the dynamical time scale of GCs and the number of BSSs along the cluster radius. This relation, however, remains to be verified in open clusters, In this study, we divide open clusters by the existence of BSSs into two groups. Then we compare parameters between these groups to specify the role of BSSs in open clusters.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.49.3-50
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• 2017

Metallicity is one of the most important properties in understanding galaxy evolution. However, measuring metallicity is limited to low redshift (z<3.5) due to the faintness of the metallicity indicators in normal galaxies. For high redshift universe, active galactic nuclei (AGN) can be used to constrain the host galaxy metallicity. Previous studies investigated AGN metallicity using emission line flux ratios (i.e., NV/CIV and FeII/MgII), finding no evolution up to z~6. Those results might be due to selection effect since previous studies are based on very luminous AGNs. The observed luminosity-metallicity relation of AGNs (e.g., Nagao et al. 2006) suggests that luminous AGNs may be already matured at the observed epoch. Considering the luminosity-metallicty relation, we focused on low luminosity AGNs to find young AGNs (i.e., low metallicity). Through the Gemini/GNIRS observation in 2012A and 2015A (K-GMT GN-2015A-Q-203 PI: Shin, J.), we obtained the Gemini/GNIRS data for 7 high redshift AGNs (3.0

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.201-203
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• 2017

There exists strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies; however it is still under debate how such a relation comes about and whether it is relevant for all or only a subset of galaxies. An important mechanism connecting AGN to their host galaxies is AGN feedback, potentially heating up or even expelling gas from galaxies. AGN feedback may hence be responsible for the eventual quenching of star formation and halting of galaxy growth. A rich multi-wavelength dataset ranging from the X-ray regime (Chandra), to far-IR (Herschel), and radio (WSRT) is available for the North Ecliptic Pole field, most notably surveyed by the AKARI infrared space telescope, covering a total area on the sky of 5.4 sq. degrees. We investigate the star formation properties and possible signatures of radio feedback mechanisms in the host galaxies of 237 radio sources below redshift z = 2 and at a radio 1.4 GHz flux density limit of 0.1 mJy. Using broadband SED modelling, the nuclear and host galaxy components of these sources are studied simultaneously as a function of their radio luminosity. Here we present results concerning the AGN content of the radio sources in this field, while also offering evidence showcasing a link between AGN activity and host galaxy star formation. In particular, we show results supporting a maintenance type of feedback from powerful radio-jets.