• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.132-132
• /
• 2013

Colloidal synthesis of nanoparticles with well-controlled size, shape, and composition, together with development of in situ surface science characterization tools, such as ambient pressure X-ray photoelectron spectroscopy (APXPS), has brought new opportunities to unravel the surface structure of working catalysts. Recent studies suggest that surface oxides on transition metal nanoparticles play an important role in determining the catalytic activity of CO oxidation. In this talk, I will outline the recent studies on the influence of surface oxides on Rh, Pt, Ru and Co nanoparticles on the catalytic activity of CO oxidation [1-3]. Transition metal nanoparticle model catalysts were synthesized in the presence of poly(vinyl pyrrolidone) polymer capping agent and deposited onto a flat Si support as two-dimensional arrays using the Langmuir-Blodgett deposition technique. APXPS studies exhibited the reversible formation of surface oxides during oxidizing, reducing, and CO oxidation reaction [4]. General trend is that the smaller nanoparticles exhibit the thicker surface oxides, while the bigger ones have the thin oxide layers. Combined with the nature of surface oxides, this trend leads to the different size dependences of catalytic activity. Such in situ observations of metal nanoparticles are useful in identifying the active state of the catalysts during use and, hence, may allow for rational catalyst designs for practical applications. I will also show that the surface oxide can be engineered by using the simple surface treatment such as UV-ozone techniques, which results in changing the catalytic activity [5]. The results suggest an intriguing way to tune catalytic activity via engineering of the nanoscale surface oxide.

• The Journal of Korean Medicine
• /
• v.41 no.3
• /
• pp.151-161
• /
• 2020

Objectives: The purpose of this study is to report the improvement of multiple rib fracture after korean medical treatment; adhesive treatment and herb-medicine treatment. Methods: A patient with multiple rib fracture was treated with Daewhangchija-paste(大黃梔子膏) adhesive and herb-medicine treatment. Verbal numeric rating scale, medical examination by interview and rib series x-ray were used to assess progress of treatment. And we took pictures of left flank after attaching Daewhangchija-paste to observe the changes of the skin colors. Results: Rib series x-ray taken after 2 months of treatment revealed hard callus which added stability against external force on rib cage. After taking off Daewhangchija-paste, left plank skin turned into blue, green and yellow. And the pain level(VNRS) of left plank decreased from 10 to 0.5 for 4 months. Conclusions: Pain reduction on trauma site and improvement of general health condition were observed during combination treatment of Daewhangchija-paste adhesive and herb-medicine.

• The Korean Journal of Ceramics
• /
• v.4 no.1
• /
• pp.25-27
• /
• 1998

The effect of gas activation on the formation of SiC layer on Si substrate using methane as a carbon source was investigated. Tungsten filaments, heated above 200$0^{\circ}C$, were used to activate the methane-hydrogen mixed gas. The dissociation of methane gas by the heated filament was enough to form a SiC layer successfully, which was very difficult without any activation. The SiC layer formed on the Si substrate was crystalline and nearly epitaxial as measured by X-ray diffraction. The SiC layer formed on the Si substrate was crystalline and nearly epitaxial as measured by X-ray diffraction. The stoichiometry was also close to 1:1. However, the characteristic of the SiC layer was dependent on the heat-treatment condition. The general behavior of the layer growth with the variables was discussed.

• BMB Reports
• /
• v.41 no.1
• /
• pp.48-54
• /
• 2008

PM0188 is a newly identified sialyltransferase from P. multocida which transfers sialic acid from cytidine 5'-monophosphonuraminic acid (CMP-NeuAc) to an acceptor sugar. Although sialyltransferases are involved in important biological functions like cell-cell recognition, cell differentiation and receptor-ligand interactions, little is known about their catalytic mechanism. Here, we report the X-ray crystal structures of PM0188 in the presence of an acceptor sugar and a donor sugar analogue, revealing the precise mechanism of sialic acid transfer. Site-directed mutagenesis, kinetic assays, and structural analysis show that Asp141, His311, Glu338, Ser355 and Ser356 are important catalytic residues; Asp141 is especially crucial as it acts as a general base. These complex structures provide insights into the mechanism of sialyltransferases and the structure-based design of specific inhibitors.

• Journal of radiological science and technology
• /
• v.8 no.2
• /
• pp.11-14
• /
• 1985

The author came to analize and get the following problems after researched radiographic quality in order to find out the necessary factors to improve in radiographs of frontal projection of the chest selected at random of the adult patients (1545 male, 1520 female) who had been examined in 4 departments of radiology of the general hospitals in Seoul and Kyungki area. 1. Problems of x-ray film or of radiographic cassette appeared in 2.97% radiographs on account of selection of the film size (except costophrenic sinus) (1.79%), poor screen-film contact (0.85%), light leakage of cassette (0,33%). 2. Problems of patients' positioning or breathing appeared in 16.57% radiographs of all because of overlapping of lung apex and clavicle (6.98%), overlapping of scapula and lung field (5.87%), asymmetrical projection of clavicles (1.76%), errors in positioning and breathing of the patient (1.96%). 3. Problems of x-ray exposure factors or film processing appeared in 22.25% radiographs because of over-density (2.64%), under-density (3.95%), fog (0.59%), demonstration density under clavicles or lung marking unsharply (3.82%), not clear of lung marking from breast region (0.94%), not clear the lung marking from the part overlapped of heart and lungs (3.92%), not clear the lung marking from the part overlapped of liver and lung (6.49%).

• Journal of The Korean Astronomical Society
• /
• v.49 no.4
• /
• pp.145-155
• /
• 2016

The Sausage radio relic is the arc-like radio structure in the cluster CIZA J2242.8+5301, whose observed properties can be best understood by synchrotron emission from relativistic electrons accelerated at a merger-driven shock. However, there remain a few puzzles that cannot be explained by the shock acceleration model with only in-situ injection. In particular, the Mach number inferred from the observed radio spectral index, M_radio ≈ 4.6, while the Mach number estimated from X-ray observations, M_X−ray ≈ 2.7. In an attempt to resolve such a discrepancy, here we consider the re-acceleration model in which a shock of M_s ≈ 3 sweeps through the intracluster gas with a pre-existing population of relativistic electrons. We find that observed brightness profiles at multi frequencies provide strong constraints on the spectral shape of pre-existing electrons. The models with a power-law momentum spectrum with the slope, s ≈ 4.1, and the cutoff Lorentz factor, γ_e,c ≈ 3−5×10⁴, can reproduce reasonably well the observed spatial profiles of radio fluxes and integrated radio spectrum of the Sausage relic. The possible origins of such relativistic electrons in the intracluster medium remain to be investigated further.

• Journal of the Korean Vacuum Society
• /
• v.14 no.3
• /
• pp.159-164
• /
• 2005

Indium tin oxide (ITO) films were deposited on a glass slide at a thickness of 280 nm by radio frequency(rf) magnetron sputtering from a ceramic target composed of $In_2O_3\;(90\%)\;+\;SnO_2\;(10\%)$. We investigated the effects of the annealing temperature (Ta) between 200 and 350'E for 30 min in air on such properties as thermal stability, surface morphology, and crystal structure of the films. X-ray diffraction spectra revealed that all the films were oriented preferably with [222] direction and [440] direction and the peak intensity increased with increasing annealing temperature. X-ray photoelectron spectroscopy (XPS) showed that the sodium was out-diffused from the glass substrate at the annealing temperature of $350^{\circ}C$. The sodium composition of the ITO film amlealed at $350^{\circ}C\;for\;30\;min\;was\;2.5\%$ at the surface. Also the sodium peak almost disappeared after 3 keV $Ar^+$sputtering for 6 min. The visible transmittance of all ITO films was over $77\%$.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.12
• /
• pp.127-139
• /
• 2017

Site investigation including boring and various in-situ borehole test (Pressuremeter test, Borehole shear test, Downhole test, Suspension PS logging, Density logging) and X-ray fluorescence analysis for rock core sample were performed to estimate geotechnical properties and weathering degree of weathered granite rock in Goyang. Deformation modulus, shear strength parameter and shear wave velocity estimated through in-situ borehole test had a tendency to increase with depth. And several chemical weathering indices evaluated by X-ray fluorescence analysis had a general tendency of reducing weathering degree in accordance with depth. Also, relationship between VR determined as a representative weathering index and the geotechnical properties was analyzed.

• The Bulletin of The Korean Astronomical Society
• /
• v.38 no.1
• /
• pp.64.1-64.1
• /
• 2013

The point spread function (PSF) of an optical system is in general defined as a two-dimensional intensity distribution which results from a single point source at infinity. It is an important key for the evaluation of the optical performance of an astronomical telescope. The PSFs of the soft X-ray telescope (SXT) aboard Yohkoh were measured in a wide range of the field-of-view under the in-flight configuration at White Sands Missile Range prior to launching the satellite. It has been known that the SXT PSF has a sharp peak at the core and the intensity drops very fast as it goes distant from the center. Due to the combination of this sharp peak at the PSF core and the effect of undersampling by a large pixel size, a carefully designed method is requested in the examination of the PSF data. The pattern of the SXT PSF is determined by the fitting of a mathematical functional form to the pre-launch experimental data. The elliptical Moffat function has been adopted for the evaluation of the SXT PSF. It is revealed from our study that the SXT PSF shows a peculiar characteristics, and thus a careful consideration on the undersampling effect and also a proper choice of statistics are necessary for the determination of the best fit function of the PSF. Details on the on- and off-axis SXT PSF in the field-of-view will be introduced and discussed in our presentation.

• Journal of the Korean Ceramic Society
• /
• v.56 no.5
• /
• pp.474-482
• /
• 2019

Chromium-doped zinc ferrite nanoparticles with the general formula Cr_yZnFe_2-yO₄ (y = 0, 0.025, 0.05, 0.075, and 0.1) were synthesized by a surfactant-assisted chemical co-precipitation route using metal nitrate salt precursors. The phase purity and structural parameters were determined by powder X-ray diffraction. The concentration of Cr³⁺ doped into ZnFe₂O₄ (ZF) noticeably affected the crystallite size, which was in the range of 22 nm to 36 nm, and all samples showed a single cubic spinel structure without any secondary phase or impurities. The lattice parameter, X-ray density, and skeletal density increased with an increase in the Cr-doping concentration; on the other hand, a decreasing trend was observed for the particle size and porosity. The influence of Cr³⁺ substitution on ZF magnetic properties were studied under an applied field of 15 kOe. The overall results revealed that the incorporation of a small amount of Cr dopant changed the structural, electrical, and magnetic properties of ZF.