• Journal of Surface Science and Engineering
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• v.41 no.6
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• pp.292-300
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• 2008

Dental implant system is composed of abutment, abutment screw and implant fixture connected with screw. The problems of loosening/tightening and stability of abutment screw depend on surface characteristics, like a surface roughness, coating materials and friction resistance and so on. For this reason, surface treatment of abutment screw has been remained research problem in prosthodontics. The purpose of this study was to investigate the stability of TiN and WC coated dental abutment screw, abutment screw was used, respectively, for experiment. For improving the surface characteristics, TiN and WC film coating was carried out on the abutment screw using EB-PVD and sputtering, respectively. In order to observe the coating surface of abutment screw, surfaces of specimens were characterized, using field emission scanning electron microscope(FE-SEM) and energy dispersive x-ray spectroscopy(EDS). The stability of TiN and WC coated abutment screw was evaluated by potentiodynamic, and cyclic potentiodynamic polarization method in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The corrosion potential of TiN coated specimen was higher than those of WC coated and non-coated abutment screw. Whereas, corrosion current density of TiN coated screws was lower than those of WC coated and non-coated abutment screw. The stability of screw decreased as following order; TiN coating, WC coating and non-coated screw. The pitting potentials of TiN and WC coated specimens were higher than that of non-coated abutment screw, but repassivation potential of WC coated specimen was lower than those of TiN coated and non-coated abutment screws due to breakdown of coated film. The degree of local ion dissolution on the surface increased in the order of TiN coated, non-coated and WC coated screws.

• The Journal of Korean Society for Radiation Therapy
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• v.20 no.2
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• pp.115-122
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• 2008

Purpose: The cancer treatment which uses radiation from next year when the X-ray is discovered with the fact that it is started. The radiation treatment technique for a cancer treatment is developed ceaselessly without and it is come and, with advancement of the computer and electromagnetic engineering it joins in and quickly, it was made to do a many development from radiation treatment field. Accordingly, this study is examine in the radiotherapy technique which is developed that importance to therapeutic principles and methods. Materials and Methods: We had investigated record for radiotherapy technique which is developed and we had acquired information widely at clinical experience data. Results: The cancer treatment which uses the radiation of today is repeating a dazzling development. Past the treatment which is two-dimensional it does not correspond in therapeutic objective but currently 3 dimension three-dimensional moulding treatment or centurial control radiation treatment this the fourth dimension therapeutic technique which is in parallel to be introduced the complication solution in compliance with a normal organization protection and the radiation which are a difficult problem of during that time radiation treatment possibly did. Conclusion: 3-dimensional and 4-dimensional modern radiation treatment which is developen is that corresponding in objective of radiation treatment and the evaluation that again it does thick, judges in about the cancer treatment which uses radiation with the fact that the protection of normal organization is almost become accomplished.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.77-77
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• 1998

Present silicon dioxide (SiOz) 떠m as intennetal dielectridIMD) layers will result in high parasitic c capacitance and crosstalk interference in 비gh density devices. Low dielectric materials such as f f1uorina뼈 silicon oxide(SiOF) and f1uoropolymer IMD layers have been tried to s이ve this problem. I In the SiOF ftlm, as fluorine concentration increases the dielectric constant of t뼈 film decreases but i it becomes unstable and wa않r absorptivity increases. The dielectric constant above 3.0 is obtain어 i in these ftlms. Fluoropolymers such as polyte$\sigma$따luoroethylene(PTFE) are known as low dielectric c constant (>2.0) materials. However, their $\alpha$)Or thermal stability and low adhesive fa$\pi$e have h hindered 야1리ru뚱 as IMD ma따"ials. 1 The concept of a plasma processing a찌Jaratus with 비gh density plasma at low pressure has r received much attention for deposition because films made in these plasma reactors have many a advantages such as go여 film quality and gap filling profile. High ion flux with low ion energy in m the high density plasma make the low contamination and go어 $\sigma$'Oss피lked ftlm. Especially the h helicon plasma reactor have attractive features for ftlm deposition 야~au똥 of i앙 high density plasma p production compared with other conventional type plasma soun:es. I In this pa야Jr, we present the results on the low dielectric constant fluorocarbonated-SiOF film d밑JOsited on p-Si(loo) 5 inch silicon substrates with 00% of 0dFTES gas mixture and 20% of Ar g gas in a helicon plasma reactor. High density 띠asma is generated in the conventional helicon p plasma soun:e with Nagoya type ill antenna, 5-15 MHz and 1 kW RF power, 700 Gauss of m magnetic field, and 1.5 mTorr of pressure. The electron density and temperature of the 0dFTES d discharge are measUI벼 by Langmuir probe. The relative density of radicals are measured by optic허 e emission spe따'Oscopy(OES). Chemical bonding structure 3I피 atomic concentration 따'C characterized u using fourier transform infrared(FTIR) s야3띠"Oscopy and X -ray photonelectron spl:’따'Oscopy (XPS). D Dielectric constant is measured using a metal insulator semiconductor (MIS;AVO.4 $\mu$ m thick f fIlmlp-SD s$\sigma$ucture. A chemical stoichiome$\sigma$y of 야Ie fluorocarbina$textsc{k}$영-SiOF film 따~si야영 at room temperature, which t the flow rate of Oz and FTES gas is Isccm and 6sccm, res야~tvely, is form려 야Ie SiouFo.36Co.14. A d dielec$\sigma$ic constant of this fIlm is 2.8, but the s$\alpha$'!Cimen at annealed 5OOt: is obtain려 3.24, and the s stepcoverage in the 0.4 $\mu$ m and 0.5 $\mu$ m pattern 킹'C above 92% and 91% without void, res야~tively. res야~tively.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.102-108
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• 2008

We have studied the properties of Ag/undoped ZnO (ZnO) multilayer thin films deposited on glass substrate by the facing targets sputtering method. In an attempt to find out the optimum conditions of the Ag thin film, which would be coated on the ZnO thin film, we investigated the changes of sheet resistance, transmittance and surface morphology as a function of deposition times and the substrate temperature. The electrical and optical characteristics of Ag/ZnO multilayers were evaluated by a four-point probe, a UV/VIS spectrometer with a spectral range of 390-770 nm, a X-ray Diffractometer (XRD), an atomic force microscope (AFM) and a Field Emission Scanning Electron Microscope (SEM), respectively. We were able to prepare the Ag/ZnO multilayer thin film with sheet resistance of 9.25 $\Omega/sq.$ and transmittance of over 80% at 550nm.

• Journal of the Korean Magnetics Society
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• v.10 no.1
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• pp.37-41
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• 2000

We investigated the magnetoresistance effect and the exchange coupling of antiferromagnetic Fe$_2$O$_3$ spin-valve film. The X-ray diffractions of the spin-valve films having a different thickness of a $\alpha$-Fe$_2$O$_3$ were measured. The exchange coupling field (H$_{ex}$) between Fe$_2$O$_3$ and pinned NiFe layer was increased from 13.5 Oe to 84.5 Oe, as the thickness of Fe$_2$O$_3$ increased from 400 $\AA$ to 800 $\AA$. The surface roughness of $\alpha$-Fe$_2$O$_3$spin-valves increased with the increase of $\alpha$-Fe$_2$O$_3$thickness. Therefore, the increase of H$_{ex}$ will be due to the increase of the interface roughness. The MR ratios as a function of Fe$_2$O$_3$ thickness was not changed. And H$_{ex}$ increased by the increment of magnetostatic coupling between Fe$_2$O$_3$ and NiFe (pinned-layer) due to the increment of interface roughness. H$_{ex}$ depends on the surface roughness, but the magnetoresistance ratio doesn't doesn't.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.355-363
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• 2015

Advancement in the medical field provides an opportunity for the development of medical equipment and also enable accurate diagnosis for the inspection and the treatment of diseases. The aging of equipment due to the frequent operation produce uncertainty in the patient exposure dose, so a quality control was implemented by establishing a safety management system on a regular basis. The x-ray tube voltage (kVp), which is directly involved in the patient exposure dose and the life of the equipment, needs periodic performance for the quality control, but it has a limitation due to the time and the cost. In this study, we proposed a new method for measuring the kVp with ease by using the Y and Cu to solve the problem of the time and cost. We also evaluated the usefulness and the effectiveness of the new method and its accuracy through the kVp measurement. After securing the condition, the amount of the tube current and evaluating the usefulness and effectiveness of kVp measured using Y and Cu. The density range used was at 0.5-1.0, kVp was in the range of ${\pm}10%$, then, we recorded the change in concentration as % of Y and Cu. This experiment showed that when Cu and Y was at 75 kVp, concentration was the same, and when the kVp was changed to 65 ~ 85 %, a gradual increase in concentration to 85 ~ 110 % was noted.

• Korean Journal of Soil Science and Fertilizer
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• v.7 no.3
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• pp.127-135
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• 1974

The samples were taken from the following localities previously classified as "Akiochi" area: Yangpyung, Puchun, and Pyungtaik, all of Kyonggi-do province. Five soil profiles were described in the field, and taken to the laboratory for physical and chemical analysis and mineralogical analysis by X-ray diffraction. The predominant clay minerals consist mainly of illite, vermiculite, chlorites and intergrade with vermiculite, and kaolinite. Illite or mica was found present in all samples and in all horizons. This was identified by the 9.83 to $10{\AA}$ (0.01) and $3.32{\AA}$ (003) basal reflections, Interhorizontal variations in mineral content and crystallinity are illustrated in their respective Xray diffractogram. Comparing the peak intensity, of the $14{\AA}$, $10{\AA}$ and $7{\AA}$ indicated the degree of weathering from the surface to the lower horizons. In general, the weathering of illite on the surface produced less pronounced $10{\AA}$ and $14{\AA}$ peak as compared to the lower horizons. The same may be said with kaolinite. On K-saturation, the $14{\AA}$ peak broadening on the low angle side was observed. This is interpreted to be due to chlorization. Heat treament from $100^{\circ}C$, $200^{\circ}C$, $400^{\circ}C$, $600^{\circ}C$, and $800^{\circ}C$. caused significant changes in the different diffractograms. Heating caused collasped of the $14{\AA}$ to $10{\AA}$ and the appearance of scattered peaks between $10-14{\AA}$. This is interpreted to the presence of vermiculite chlorite intergradient. The complete collapse of the $14{\AA}$ at $800^{\circ}C$ to $10{\AA}$ with increased intensity was attributed to the preservce of vermiculite. The principal difference among the clay minerals in each horizon is the concomitant increase and decrease in intensity with depth of the $14{\AA}$, $10{\AA}$ and $7{\AA}$ diffraction spacings. Apparently the weathering of illite ($10{\AA}$) is resulting in the formation of vermiculite ($14{\AA}$) and the interstratified material being an intermediate stage and the beginning of the formation of vermiculite. Some broadening- in the 17 to $18{\AA}$ was observed in Puchun-1 Pyungtaik-1 and Pyungtaik-2 specially so in the lower horizon in the Ca or Mg-saturated sample. Heated treatment tend to shift this peak to $14{\AA}$ indicating the presence of regular layering of the interstratified complex. The high amount of extractable aluminum and iron coupled with low exchange capacity indicate that iron and aluminum plays an important role in the weathering of these soils and is responsible to the low exchange capacity, high acidity and high phosphate absorptive capacity. The results presented substantiated the weathering sequence of Jackson in that mica ${\rightarrow}$ vermiculite ${\rightarrow}$ chloritezed vermiculite ${\rightarrow}$ kaolinite.

• Journal of the Korean Society of Radiology
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• v.9 no.3
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• pp.169-174
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• 2015

$LiGd_9(SiO_4)_6O_2:Ce^{3+}$ phosphors were synthesized by solid-state reaction method. The structural characteristic was investigated by X-ray powder diffraction analysis. The emission and excitation spectra of the $Ce^{3+}$ ions doped $LiGd_9(SiO_4)_6O_2$ phosphors were obtained under the UV excitation. The emission spectra of $LiGd_9(SiO_4)_6O_2:Ce^{3+}$ shows the band at 410 nm corresponding to the $^2F_{5/2}$ and $^2F_{7/2}$ states of $Ce^{3+}$. The red shift of $Ce^{3+}$ emission is found as the $Ce^{3+}$ concentration increases, which could be explained by the change in crystal-field symmetry and strength with increasing $Ce^{3+}$ concentration. Fluorescence decay time of $Ce^{3+}$ was about 20 ns. When the concentration of $Ce^{3+}$ increases life time was slightly reduced.

• Journal of Powder Materials
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• v.24 no.4
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• pp.302-307
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• 2017

In this study, Fe-Cu-C alloy is sintered by spark plasma sintering (SPS). The sintering conditions are 60 MPa pressure with heating rates of 30, 60 and $9^{\circ}C/min$ to determine the influence of heating rate on the mechanical and microstructure properties of the sintered alloys. The microstructure and mechanical properties of the sintered Fe-Cu-C alloy is investigated by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The temperature of shrinkage displacement is changed at $450^{\circ}C$ with heating rates 30, 60, and $90^{\circ}C/min$. The temperature of the shrinkage displacement is finished at $650^{\circ}C$ when heating rate $30^{\circ}C/min$, at $700^{\circ}C$ when heating rate $60^{\circ}C/min$ and at $800^{\circ}C$ when heating rate $90^{\circ}C/min$. For the sintered alloy at heating rates of 30, 60, and $90^{\circ}C/min$, the apparent porosity is calculated to be 3.7%, 5.2%, and 7.7%, respectively. The hardness of the sintered alloys is investigated using Rockwell hardness measurements. The objective of this study is to investigate the densification behavior, porosity, and mechanical properties of the sintered Fe-Cu-C alloys depending on the heating rate.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.502-507
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• 2016

This study was conducted to develop novel antimicrobial nano-composites, with the aim of fully utilizing antimicrobial properties of multi-walled carbon nanotubes (MWCNTs), nickel (Ni) and zinc oxide (ZnO). Ni coated-MWCNTs (Ni-CNT) were prepared and evaluated for their potential application as an antimicrobial material for inactivating bacteria. Field emission scanning electron microscopy (FE-SEM), and X-ray energy dispersive spectroscopy (EDS) were used to characterize the Ni coating and morphology of Ni-CNT. Staphylococcus aureus (S. aureus) and Escherichia coil (E. coil) were employed as the target bacterium on antimicrobial activities. Comparing with the nitric acid treated MWCNTs and Ni-CNT which have been previously reported to possess antimicrobial activity towards S. aureus and E. coil, Ni-CNT/ZnO exhibited a stronger antimicrobial ability. The nickel coating was confirmed to play an important role in the bactericidal action of Ni-CNTs/ZnO composites. Also, the addition of ZnO to the developed nanocomposite is suggested to improve the antimicrobial property.