• Korean Journal Plant Pathology
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• v.13 no.3
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• pp.160-166
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• 1997

Number of bacterial isolates were collected from high mountainous areas at various locations in the whole country to select promising biocontrol agents. Most of selected isolates belonged to fluorescent pseudomonads. Population densities of fluorescent pseudomonads were examined by DLF method. Alll selected isolates rapidly multiplied on spermosphere after seed inoculation upto 24, and then the population abruptly declined. When seeds were germinated fully, bacteria moved to newly emerging radicle. The good root colonizing isolates, B16 and V13 proliferated on the growing root and moved down to the root tip and lateral roots. but the poor root colonizing isolates, MC07 and X01 moved much slower. Scanning electron microscopic observations showed that the cells of the good colonizing isolates were arranged linearly on the growing root and parallel to growing root axis and continuously existed on the root tip, Whereas the cells of poorly colonizing isolates were gathered and scattered randomly on the root surface.

• Applied Microscopy
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• v.40 no.1
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• pp.15-19
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• 2010

The present study was designed to demonstrate ionic zinc in the rat DRG by means of zinc selenium autometallography($ZnSe^{AMG}$). Ganglion cells varied in size from 15 to 100 ${\mu}m$. The smaller neurons were strongly stained with AMG, whereas the larger cells were weakly stained. Each large ganglion cell was surrounded by perineuronal satellite cells, showing apparent AMG staining. We demonstrated for the first time the existence of zinc-containing satellite cells in the rodent DRG. Using electron microscopy, fine AMG grains were observed scattered in the somata of the DRG neurons, especially small cells. However, much lower concentrations of the AMG grains occupied in the large cells, and these were mostly localized in lysosome-like organelles. These results indicate that zinc may be involved in sensory transmission in the DRG level.

• Journal of the Mineralogical Society of Korea
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• v.15 no.1
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• pp.22-32
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• 2002

Mineral composition and chemistry of the clay minerals in the three cores from the continental shelves of South Shetland Islands (NCS09) and Anberse Island (GC98-2), and from the fjord of King George Island (A10-01) were determined by X-ray diffraction and electron microprobe analysis in search of the distributions and origin of the clay minerals in the Antarctic marine sediments. Smectite content is relatively high in NCS09 regardless of core depths (av. 8.3%), but low in GC98-2 (1.1%). In Al0-01, smectite content is higher in the upper section than in the lower section. Kaolinite was not detected from all the cores in this study Yellow to yellowish green clay granules were commonly scattered in the sediments of NCS09 cores. The clays contain 16.97% and 2.53% $Fe_2$$O_3$와 $K_2$O. Average structural formula of the clay indicates ferrian beidellite . The (Fe, K)-rich smectite of NSC09 must have been derived from relatively young basaltic volcanics altered by reaction with seawater near Shetland Islands by glacial erosion or eolian process related to volcanic eruption. GC98-2 nearer to Antarctic continent is very low in smectite content. In A10-01, the lower diamicton was deposited from the glacial erosion of smectite-free ancient volcanics in the interior of King George Island, while the upper section was derived from the smectite-bearing terrestrial debris and eolian materials after retreat of glaciers in Marian Cove and ice cover in Barton Peninsula. Thehigh K contents of smectites suggest the interstratification of illite and smectite layers, which might be observed by future TEM lattice fringe imaging.

• Korean Journal of Materials Research
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• v.21 no.5
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• pp.263-267
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• 2011

The present study was carried out to evaluate the microstructural and mechanical properties of cross-roll rolled pure copper sheets, and the results were compared with those obtained for conventionally rolled sheets. For this work, pure copper (99.99 mass%) sheets with thickness of 5 mm were prepared as the starting material. The sheets were cold rolled to 90% thickness reduction and subsequently annealed at $400^{\circ}C$ for 30 min. Also, to analyze the grain boundary character distributions (GBCDs) on the materials, the electron back-scattered diffraction (EBSD) technique was introduced. The resulting cold-rolled and annealed sheets had considerably finer grains than the initial sheets with an average size of 100 ${\mu}M$. In particular, the average grain size became smaller by cross-roll rolling (6.5 ${\mu}M$) than by conventional rolling (9.8 ${\mu}M$). These grain refinements directly led to enhanced mechanical properties such as Vickers micro-hardness and tensile strength, and thus the values showed greater increases upon cross-roll rolling process than after conventional rolling. Furthermore, the texture development of <112>//ND in the cross-roll rolling processed material provided greater enhancement of mechanical properties relative to the case of the conventional rolling processed material. In the present study, we systematically discuss the enhancement of mechanical properties in terms of grain refinement and texture distribution developed by the different rolling processes.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.208-213
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• 1999

Space Physics Sensor (SPS) on-board the KOMPSAT-1 consists of the High Energy Particle Detector (HEPD) and the Ionospheric Measurement Sensor (IMS). The HEPD is to characterize the low altitude high energy particle environment and the effects on the microelectronics due to these high energy Particles. It is composed of four sensors: Proton and Electron Spectrometer(PES), Linear Energy Transfer Spectrometer (LET), Total Dose Monitor (TDM), and Single Event Monitor(SEM). 35MeV proton beam from the medical KCCH cyclotron, at Korea Cancer Center Hospital in Seoul, is used to calibrate the PES. Primary proton beam of 35MeV scattered by polypropylene target is converted to various energy Protons according to the elastic collision kinematics. In this calibration, the threshold level of the proton in the PES can be determined and the energy ranges of PES channels are also calibrated.

• Journal of Nutrition and Health
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• v.17 no.3
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• pp.224-235
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• 1984

Vitamin E status affected by dietary high PUFA and Se was examined by biochemical and morphological means. Rats were fed four different diets(I : 15% p/s=1 control diet, II : 15% perilla oil diet, III : 15% perilla oil, vitamin mix -vitamin E, IV : 15% perilla oil, vitamin mix-vitamin E and salt mix -Se ) for $4\frac{1}{2}$ weeks. Various dietary treatments had no significant effects on body weight gains of rats. Activities of serum creatine phosphokinase known as an indicator of vitamin E deficiency were significantly higher( P < 0.001) in groups fed diets high in PUFA, regardless of the addition or omission of vitamin E from the vitamin mixture than those in control group. Vitamin E concentrations of serum and liver were affected by experimental diets and serum levels were more affected than those in liver. Electron microscopic observations of the liver revealed 1) the presence of swollen and degenerated mitochondria and lysosome-like body(II), and 2) markedly swollen and degenerated mitochondria, numerous lysosomes and decreased in size and number of microvilli along the bile canaliculus ( III, and 3) a remarkable accumulation of lipid droplets, nuclear pyknosis, degenerated mitochondria and increased number of lysosomes scattered along the cell junction in the hepatocytes (IV).

• Economic and Environmental Geology
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• v.53 no.2
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• pp.183-196
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• 2020

This study aimed to recover native gold from the concentrate using microwave-nitric acid leaching and magnetic/hydro separation experiments. The insoluble-residue was filtered from leaching solution through microwave-nitric acid leaching experiment. As a result of the atomic absorption spectrometer(AAS) analysis of the filtered leaching solution, it was discovered that Au content was not eluted at all and it was observed from the back scattered electron(BSE) image that native gold was liberated in the insoluble-residue. When magnetic/hydro separation experiments were applied for the insoluble-residue, magnetic and non magnetic minerals were separtated from insoluble-residue. Magnetite was recovered from the magnetic minerals and as a result of applying the hydro separation experiment again for the non-magnetic mineral, native gold was recovered. The native gold was identified through the X-ray diffraction(XRD) analysis and BSE image.

• International Journal of Safety
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• v.6 no.2
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• pp.1-7
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• 2007

In this study mechanical strength of A53B carbon steel was analyzed using several types of test specimens directly machined from oil recycling pipe experienced a failure due to hydrogen attack in chemical plants. High temperature hydrogen attack (HTHA) is the damage process of grain boundary facets due to a chemical reaction of carbides with hydrogen, thus forming cavities with high pressure methane gas. Driven by the methane gas pressure, the cavities grow on grain boundaries forming intergranular micro cracks. Microscopic optical examination, tensile test, Charpy impact test, hardness measurement, and small punch (SP) test were performed. Carbon content of the hydrogen attacked specimens was dramatically reduced compared with that of standard specification of A53B. Traces of decarburization and micro-cracks were observed by optical and scanning electron microscopy. Charpy impact energy in hydrogen attacked part of the pipe exhibited very low values due to the decarburization and micro fissure formation by HTHA, on the other hand, data tested from the sound part of the pipe showed high and scattered impact energy. Maximum reaction forces and ductility in SP test were decreased at hydrogen attacked part of the pipe compared with sound part of the pipe. Finite element analyses for SP test were performed to estimate tensile properties for untested part of the pipe in tensile test. And fracture toughness was calculated using an equivalent strain concept with SP test and finite element analysis results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.469-474
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• 2005

Tn this study, the noll-destructive computed X-ray tomography was adopted to observe the density distribution of the needle-punched C-C composites nozzle throat. The density distribution of the C-C was evaluated within ${\pm}0.01g/cm^3$ with 98.74% confidence when the correction of the image and high signal-to-noise ratio were achieved by the optimization of the beam hardening, the electrical noise and the scattered X-ray. The density variation of the C/C with the computed tomography was in good agreement with the results obtained by the water immersion method and the observation with scanning electron microscope.

• Journal of The Korean Astronomical Society
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• v.51 no.1
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• pp.5-16
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• 2018

We investigate the escape of $Ly{\beta}$ from emission nebulae with a significant population of excited hydrogen atoms in the level n = 2, rendering them optically thick in $H{\alpha}$. The transfer of $Ly{\beta}$ line photons in these optically thick regions is complicated by the presence of another scattering channel leading to re-emission of $H{\alpha}$, alternating their identities between $Ly{\beta}$ and $H{\alpha}$. In this work, we develop a Monte Carlo code to simulate the transfer of $Ly{\beta}$ line photons incorporating the scattering channel into $H{\alpha}$. Both $H{\alpha}$ and $Ly{\beta}$ lines are formed through diffusion in frequency space, where a line photon enters the wing regime after a fairly large number of resonance scatterings with hydrogen atoms. Various line profiles of $H{\alpha}$ and $Ly{\beta}$ emergent from our model nebulae are presented. It is argued that the electron temperature is a critical parameter which controls the flux ratio of emergent $Ly{\beta}$ and $H{\alpha}$. Specifically for $T\;=\;3{\times}10^4\;K$ and $H{\alpha}$ line center optical depth $\tau{\alpha}\;=\;10$, the number flux ratio of emergent $Ly{\beta}$ and $H{\alpha}$ is ~ 49 percent, which is quite significant. We propose that the leaking $Ly{\beta}$ can be an interesting source for the formation of $H{\alpha}$ wings observed in many symbiotic stars and active galactic nuclei. Similar broad $H{\alpha}$ wings are also expected in $Ly{\alpha}$ emitting halos found in the early universe, which can be potentially probed by the James Webb Telescope in the future.