• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.467-470
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• 2004

Diamond-Like Carbon (DLC) thin film is a semiconductor with high mechanical hardness, low friction coefficient, high chemical inertness, and optical transparency. DLC thin films have widespread applications as protective coatings and solid lubricant coatings in areas such as Hard Disk Drive (HDD) and Micro-Electro-Mechanical-Systems (MEMS). In this work, the wear characteristics of DLC thin films deposited on silicon substrates using a DC-magnetron sputtering system were analyzed. The wear tracks were measured with an Atomic Force Microscope (AFM). To identify the sp2 and sp3 hybridization of carbon bonds and other bonds Raman spectroscopy was used. The structural information of DLC thin films was obtained with Fourier transform infrared spectroscopy and wear tests were conducted by using a micro-pin-on-reciprocator tester. Results showed that the wear characteristics were dependent on the sputtering conditions. The wear rate could be correlated with the bonding state of the DLC thin film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.747-751
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• 2010

In the study, the characteristics of the etched Zinc oxide (ZnO) thin films surface, the etch rate of ZnO thin film in $Cl_2/BCl_3/Ar$ plasma was investigated. The maximum ZnO etch rate of 53 nm/min was obtained for $Cl_2/BCl_3/Ar$=3:16:4 sccm gas mixture. According to the x-ray diffraction (XRD) and atomic force microscopy (AFM), the etched ZnO thin film was investigated to the chemical reaction of the ZnO surface in $Cl_2/BCl_3/Ar$ plasma. The field emission auger electron spectroscopy (FE-AES) analysis showed an elemental analysis from the etched surfaces. According to the etching time, the ZnO thin film of etched was obtained to The AES depth-profile analysis. We used to atomic force microscopy to determine the roughness of the surface. So, the root mean square of ZnO thin film was 17.02 in $Cl_2/BCl_3/Ar$ plasma. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the plasmas.

• Journal of Powder Materials
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• v.14 no.2 s.61
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• pp.127-131
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• 2007

The alumina nano powders synthesized by levitational gas condensation (LGC) method were applied to catalyst in manufacturing process of Hanzsch reaction for Nitrendipine. The L-tartaric acid on the surface is carried out with participation of carbonyl fragments, O-H, C-H bonds which affects stereo selectivity, yield on the reagents positively. From the analysis of the IR-spectroscopy, the carbonyl fragments, O-H, and C-H bond were created by the catalytic reaction. From the analysis of the rR-spectroscopy, the carbonyl fragments, O-H, and C-H bond were created by the catalytic reaction. The newly created bonds made a chiral center on the final product.

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

• Proceedings of the Korean Vacuum Society Conference
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• 2004.08a
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• pp.56-56
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• 2004

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.222-222
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• 2011

Titanium dioxide (TiO2) has a number of applications in optics and electronics due to its superior properties, such as physical and chemical stability, high refractive index, good transmission in vis and NIR regions, and high dielectric constant. Atomic layer deposition (ALD), also called atomic layer epitaxy, can be regarded as a special modification of the chemical vapor deposition method. ALD is a pulsed method in which the reactant vapors are alternately supplied onto the substrate. During each pulse, the precursors chemisorb or react with the surface groups. When the process conditions are suitably chosen, the film growth proceeds by alternate saturative surface reactions and is thus self-limiting. This makes it possible to cover even complex shaped objects with a uniform film. It is also possible to control the film thickness accurately simply by controlling the number of pulsing cycles repeated. We have investigated the ALD of TiO2 at 100$^{\circ}C$ using precursors titanium tetra-isopropoxide (TTIP) and H2O on -O, -OH terminated Si surface by in situ X-ray photoemission spectroscopy. ALD reactions with TTIP were performed on the H2O-dosed Si substrate at 100$^{\circ}C$, where one cycle was completed. The number of ALD cycles was increased by repeated deposition of H2O and TTIP at 100$^{\circ}C$. After precursor exposure, the samples were transferred under vacuum from the reaction chamber to the UHV chamber at room temperature for in situ XPS analysis. The XPS instrument included a hemispherical analyzer (ALPHA 110) and a monochromatic X-ray source generated by exciting Al K${\alpha}$ radiation (h${\nu}$=1486.6 eV).

• Analytical Science and Technology
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• v.16 no.1
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• pp.12-24
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• 2003

For the design and set-up of neutron induced prompt ${\gamma}$-ray spectroscopy system using $^{252}Cf$ neutron source, the effects of shielding and moderator materials have been examined. The $^{252}Cf$ source being used for TLD badge calibration in Korea Atomic Energy Research Institute was utilized for this preliminary experiment. The ${\gamma}$-ray background and prompt ${\gamma}$-ray spectrum of the sample containing Cl were measured using HPGe (GMX 60% relative efficiency) located at the inside of the system connected to notebook PC at the outside of the system (about 20 meter distance). The background activities of neutron and ${\gamma}$-rays were measured with neutron survey meter as well as ${\gamma}$-ray survey meters, respectively and the system was designed to minimize the activities. Prompt ${\gamma}$-ray spectrum was measured using ${\gamma}$-${\gamma}$ coincident system for reduce the background and the continuum spectrum. The optimum system was designed and set up using the experimental data obtained.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.4
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• pp.717-721
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• 2002

Study was carried out with electron spin resonance (ESR) spectroscopy to identify irradiated Korean medicinal herbs. Pueraria thunbergiana Benth., Angelica gigas Nakai, Agaricus blazei Murill and Astragalus membranaceus Bunge were irradiated with doses of 0, 1, 5 and 10 kGy at room temperature using a Co-60 irradiator. The irradiated Korean medicinal herbs exhibited an asymmetric absorption, which was different from the non-irradiated ones. The strength of ESR signals linearly increased by dose-dependent manner (1~10 kGy) and highly positive correlation coefficients ($R^2$=0.9428~0.9942) were obtained between the irradiation doses and the corresponding ESR signal intensities. Detection of the irradiated Korean medicinal herbs was possible even after 6 weeks of storage although the signal intensities of the irradiated samples decreased until 2 weeks at room temperature.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.215-219
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• 2008

The bonding structure and composition of silicon nitride (SiNx) films were investigated by using Fourier transform infrared spectroscopy (FT-IR). SiNx films were deposited on Si substrate at $340^{\circ}C$ using a conventional PECVD system. The compositions of Si and N in SiNx films were confirmed by using Rutherford backscattering spectroscopy (RBS) and photoluminescence (PL) analysis. The surface morphology of SiNx films was also analyzed by using atomic force microscopy (AFM). It was found that the contents of NH(at. %) is the reverse related with those of SiH corresponding to the result of FT-IR. we conclude that a quantitative analysis on SiNx films can be possible through a precise detection of the contents of H in SiNx films with a FT-IR analysis only.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.420.1-420
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• 2002

Thermal decomposition reaction of gas-phase UO2(hfacac)2. THF was investigated in a static cell. IR spectroscopic method was used to study the thermal decomptsition of gas phase uranyl complexes. The decomposition reaction products were separated by using thermal-gradient fractional sublimation method utilizing the differences in their volatility.