• Korean Chemical Engineering Research
• /
• v.49 no.3
• /
• pp.357-360
• /
• 2011

N-doped ZnO nanofilms were prepared by plasma enhanced atomic layer deposition method. $Zn(C_{2}H_{5})_{2}$, $O_{2}$ and $N_{2}$ were used as Zn, O and N sources, respectively, for N-doped ZnO films under variation of radio frequency (rf) power from 50-300W. Structural, optical and electrical properties of as-grown ZnO films were investigated with Xray diffraction(XRD), photoluminescence(PL) and Hall-effect measurements, respectively. Nitrogen content and p-type conductivity in ZnO nanofilms increased with the rf power.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.30 no.2 s.245
• /
• pp.170-176
• /
• 2006

A spark discharge aerosol generator using air as a carrier gas has successfully been applied to silver nanoparticle production. The spark discharge between two silver electrodes, which was periodically obtained by discharging the capacitor, produced sufficient high temperatures to evaporate a small fraction of the silver electrodes. The silver vapor was subsequently supersaturated by rapid cooling and condensed to silver nanoparticles by nucleation and condensation. The morphology of the generated particles observed by transmission electron microscope was spherical. The element composition of the nanoparticles was silver, which was determined by energy dispersive X-ray spectroscopy. The crystal phase of the particles spark-generated under air atmosphere was composed of silver and silver oxides phase, which was determined by Xray diffraction analysis. While the nanoparticles generated under nitrogen atmosphere had only silver phase. This XRD data indicates that some fraction of the evaporated silver vapor could be oxidized in air atmosphere by the reaction with oxygen. A stable operation of the spark discharge generator has been achieved. The size and concentration of the particles can be easily controlled by altering the repetition frequency, capacitance, gap distance and flow rate of the spark discharge system.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.9
• /
• pp.3255-3260
• /
• 2011

Two novel binuclear metal-organic coordination complexes $[Cd_2(L)_2(bpy)_2(H_2O)_2]{\cdot}6H_2O$ (1), $[Cd_2(L)_2(phen)_2-(H_2O)_2]{\cdot}2H_2O$ (2) (where L = 2-methylquinoline-3,4-dicarboxylate dianion, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions and characterized by single crystal Xray diffraction, spectral method (IR), elemental analysis and thermal gravimetric analysis (TGA). Both 1 and 2 consist of two Cd(II) atoms bridged by two monoatomic bridging carboxylate groups from two L ligands, and the second carboxylate group of each L is monodentately coordinated to Cd(II), creating a sevenmembered chelating ring. The coordination at each metal nucleus is completed by a water molecule and a chelating bidentate molecule. The 3D structures of the complexes are stabilized by ${\pi}-{\pi}$ stacking interactions and hydrogen-bonds.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.1
• /
• pp.72.2-72.2
• /
• 2012

We present the results of HI 21 cm line observations to explore the nature of the high-velocity (HV) HI gas at - 173${\circ}$, which appears as faint, wing-like, Hi emission that extends to velocities beyond those allowed by Galactic rotation in the low-resolution surveys. We designate this feature as Forbidden Velocity Wing (FVW) 172.8+1.5. Our high-resolution Arecibo HI observations show that FVW 172.8+1.5 is composed of knots, filaments, and ring-like structures distributed over an area of a few degrees in extent. These HV HI emission features are well correlated with the HII complex G173+1.5, which is composed of five Sharpless HII regions distributed along a radio continuum loop of size 4.4${\times}$3.4, or -138 pc ${\times}$ 107 pc, at a distance of 1.8 kpc. G173+1.5 is one of the largest star-forming regions in the outer Galaxy. The HV HI gas and the radio continuum loop seem to trace an expanding shell. Its derived HI parameters including large expansion velocity (55 km/s) imply the SNR interpretation. Hot xray emission is detected within the HII complex, which also supports its SNR origin. The FVW172.8+1.5 is most likely the products of a supernova explosion(s) within the HII complex, possibly in a cluster that triggered the formation of these HII regions.

• Journal of Technologic Dentistry
• /
• v.15 no.1
• /
• pp.5-25
• /
• 1993

Effects of hydrogenation on microstructure and mechanical properties of pure Ti and Ti-0.15Pd alloy have been studied by means of optical microscopy, differential scanning calorimeter(DSC), Xray diffraction and micro vicker's hardness test. Grain size of pure Ti and Ti-0.15Pd alloy decresed largely by hydrogenation finer than that of pure Ti and the grain size refinement was evedent in Ti-0.15Pd alloy than that in pure Ti. Ti-.015Pd alloy carried out solution treatment at 950$^{\circ}C$, the transformation of $\alpha$' martensite was occured. The amount of Hydrogen absorption in Ti-.015Pd alloy was higher than that in pure Ti. Decomposition of hydride in pure titanium and Ti-0.15Pd alloy increased largely by hydrogenation, and micro vicker's hardness of Ti-.015Pd alloy was largely than that of pure Ti by 30% after hydrogenation. The micro vicker's hardness of Ti-0.15Pd alloy after solution treatment and dehydrogenation were higher at $\beta$ phase ranger(950$^{\circ}C$) than that phase range(750$^{\circ}C$).

• Journal of the Korean institute of surface engineering
• /
• v.41 no.4
• /
• pp.163-168
• /
• 2008

The dental orthodontic bracket requires good mechanical properties, such as elastic strength and frictional resistance, combined with a high resistance to corrosion. The objective of this study was to investigate the effects of TiN and ZrN coating on corrosion resistance of orthodontic brackets using various electrochemical methods. Brackets manufactured by Ormco Co. were used, respectively, for experiment. Ion plating was carried out for coatings of bracket using Ti and Zr coating materials with nitrogen gas. Ion plated surface of each specimen was observed with field emission scanning electron microscopy(FE-SEM), energy dispersive Xray spectroscopy(EDS) and electrochemical tester. The corrosion potential of the TiN and ZrN coated bracket was comparatively high. The current density of TiN and ZrN coated bracket was smaller than that of non-coated bracket in 0.9% NaCl solution. Pit nucleated at angle of bracket slot.

• The Journal of Churna Manual Medicine for Spine and Nerves
• /
• v.6 no.1
• /
• pp.19-26
• /
• 2011

Objectives : The purpose of this study is to research the necessity of sacral base X-ray that Barge insisted. Methods : I have done a comparative analysis in side of short leg and side of sacral inferior with sacral base X-ray and pelvis A-P Xray pictures of 42 patients with lower back pain from December 1, 2010 to March 31, 2011. Results : Even though most of the subjects in study were male, 36 people had plateau of sacral base and 29 people had symmetry in sacral base X-ray. There was no statistical significance in the side of short leg and side of sacral base inferior in Sacral base X-ray, but there was a statistical significance in pelvis A-P x-ray. 22 people had same side of short leg and side of sacral base inferior in sacral base X-ray and pelvis A-P X-ray and 14 people didn't. 29 people had same side of sacral base inferior in sacral base X-ray and pelvis A-P X-ray and 13 people didn't. Conclusions : According to the result of the study, sacral base X-ray is necessary for correct sacral base inferior analysis.

• Journal of the Optical Society of Korea
• /
• v.4 no.1
• /
• pp.7-10
• /
• 2000

The soft x-ray(10nm-100nm) interferometer is a modified Mach-Zehnder type interferometer and it consists of two beam-splitters and four totally reflecting mirrors. The beam-splitters used here are 50% transmission and 50% reflection grating type. The diffraction patterns of beam splitters(1st B.S.) were investigated with a He-Ne laser. The diffraction patterns produced by the soft x-ray interferometer (2nd B.S.) were also investigated in intensities positions. The diffraction patterns of 20 degree grazing incidence on the beam splitters(1st B.S.) show a circular array of spots. Both the reflected and the transmitted beams show the same patterns but symmetric circles on the screen. The maximum intensity appears roughly when n is in the zeroth and odd orders and the suppressed peak(missing order) appears when n is in even orders. Intensities of 3 center fringes(n = 0, $\pm$1) are stronger than others. These results confirm the reduced grating equation and make agree with the intensity distribution function. It was found that the final patterns produced by the soft x-ray interferometer (2nd B.S.) consisted of fine fringes which were caused by two of three diffraction beams that were arrived at the second beam-splitter.

• Food Science and Biotechnology
• /
• v.18 no.5
• /
• pp.1145-1149
• /
• 2009

Physicochemical properties of native and acid-modified Job's tears (Coix lachryma-jobi L.) starches were investigated. Starch extracted from Job's tears was treated with 2.2 N hydrochloric acid for different length of time (3, 6, 12, and 18 hr). The hydrolysis pattern of starches with the acid proceeded rapidly up to 12 hr and then the approached constant values. The swelling power of acid-modified starches measured at all temperatures was lower than that of its native counterparts and the water solubility index increased as temperature and hydrolysis time increased. Rapid visco analyzer viscograms of acid-modified starches demonstrated a very low viscosity as compared with that of native starch. However, Xray diffraction did not show any significant alteration in the crystallinity after acid-modification.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.317-317
• /
• 2011

Enhanced ICRF (Ion Cyclotron Range of Frequency) ion heating of H-mode D(H) plasma will be tried in 2011 KSTAR experimental campaign. Minority heating is a main ion heating scheme in the ICRF. Its efficiency increases as the hydrogen minority ratio increases in deuterium plasmas. And it should be sustained at a lower level than the critical minority ratio. Consequently, it is important to elevate the critical ratio to maximize ion heating and it is possible by increasing the ion temperature or parallel wave number (k${\parallel}$) of the antenna. Increasing the k${\parallel}$ is not a good approach since the coupling efficiency decreases exponentially with regard to k${\parallel}$ as well. So the remaining method is to increase ion temperature by using NB (Neutral Beam). Ion heating fraction of NB increases as the electron temperature increases. Therefore, we will try to heat electron by using ECH together with NB ion heating before ICRF power injection. The ICRF heating efficiency will be compared with respect to several NB+ECH+ICRF heating combinations through several diagnostics such as XICS (Xray Imaging Crystal Spectroscopy), CES (Charge Exchange Spectroscopy) and neutron measurement. The theoretical background and the experimental results will be presented in more detail in the conference.