• 한국표면공학회지
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• 제29권5호
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• pp.399-406
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• 1996

The orientational cross-over phenomena in an RF sputtering growth of TiN films were studied in an in-situ, real-time synchrotron x-ray scattering experiment. For the films grown with pure Ar sputtering gas, the cross-over from the more strained (002)-oriented grains to the less strained (111)-oriented grains occurred as the film thickness was increased. As the sputtering power was increased, the cross-over thickness, at which the growth orientation changes from the <002> to the <111> direction, was decreased. The addition of $N_2$ besides Ar as sputtering gas suppressed the cross-over, and consequently resulted in the (002) preferred orientation without exhibiting the cross-over. We attribute the observed cross-over phenomena to the competition between the surface and the strain energy. The x-ray powder diffraction, the x-ray reflectivity, and the ex-situ AFM surface topology study consistently suggest that the microscopic growth front was in fact always the (002) planes. In the initial stage of growth, the (002) planes were aligned to the substrate surface to minimize the surface energy. At later stages, however, the (002) growth front tilted away from the surface by about $60^{\circ}$ to relax the strain, which caused the cross-over of the preferred growth direction to the <111> direction.

• Journal of Radiation Protection and Research
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• 제34권1호
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• pp.25-30
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• 2009

Micro-columnar CsI(Tl) is the most popular scintillator material which is used for many indirect digital X-ray imaging detectors. The light scattering at the surface of micro-columnar CsI(Tl) scintillator was studied to find the correlation between the surface roughness and the resultant image resolution of indirect X-ray imaging detectors. Using a commercially available optical simulation program, Light Tools, MTF (Modulation Transfer Function) curves of the CsI(Tl) film thermally evaporated on glass substrate with different thickness were calculated and compared with the experimental estimation of MTF values by the edge X-ray image method and CCD camera. It was found that the standard deviation value of Gaussian scattering model which is determined by the surface roughness of micro-columns could certainly change the MTF value of image sensors. This model and calculation methodology will be beneficial to estimate the overall performance of indirect X-ray imaging system with CsI(Tl) scintillator film for optimum design depending on its application.

• 한국전기전자재료학회논문지
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• 제13권3호
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• pp.188-192
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• 2000

In this study PZT etching was performed using planar inductively coupled Ar/Cl$_2$/BCI$_3$ plasma. The etch rate of PZT film was 2450 $\AA$/min at Ar(20)/BCl$_3$(80) gas mixing ratio and substrate temperature of 8$0^{\circ}C$. X-ray photoelectron spectroscopy(XPS) analysis for films composition of etched PZT surface was utilized. The chemical bond of PbO is broken by ion bombardment and Cl radical, and the peak of metal Pb in a Pb 4f narrow scan begins to appear upon etching. As increasing additive BCl$_3$content the relative content of oxygen decreases rapidly in contrast with etch rate of PZT thin film. So we though that the etch rate of PZT thin film increased because abundant B and BCl radicals made volatile oxy-compound such as B$_{x}$/O$_{y}$ and/or BClO$_{x}$ bond. We achieved etch profile of about 80$^{\circ}$ at Ar(20)/BCl$_3$(80) gas mixing condition and substrate temperature of 8$0^{\circ}C$TEX>X>.

• 한국진공학회지
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• 제17권3호
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• pp.234-239
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• 2008

휴대용 XRF (X-Ray Fluorescence) 장치에 적용할 수 있는 40 kV용 투과 양극형 W-Target tube와 Rh-Target tube를 개발하고 특성을 조사하였다. 특성 x-ray의 에너지와 연속 x-ray의 선량특성은 알려진 결과와 잘 일치함을 확인하였고, 최대 선량을 추출하기 위한 양극금속 박막의 최적 두께는 W-target tube의 경우 약 $2.6{\mu}m$, Rh-target tube의 경우 약 $2.7{\mu}m$ 임을 밝혀내었다. 또한 관전압 40 kV, 관전류 $60{\mu}A$로 30분 동안 연속적으로 작동시켰을 때 양극에서의 온도는 $50^{\circ}C$를 넘지 않아 휴대용 XRF장치에 적용할 수 있음을 확인하였다.

• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.539-542
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• 2002

The effect of the superconducting film thickness on the surface resistance has been investigated. Superconducting YBCO thin films have been grown on MgO substrates by pulsed laser deposition. The dependence of the orientation of YBCO film on thickness has been investigated by X-ray diffraction technique. X-ray diffraction indicated that the film orientation was changed by increasing the film thickness and by changing the substrate temperature. The microwave properties of the films with mixed orientations of a-axis and c-axis will be reported for the applications of microwave devices.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권3호
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• pp.109-115
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• 2003

Diamond-like carbon (DLC) films are deposited at room temperature using a filtered cathodic vacuum arc (FCVA) technique. The influence of negative bias voltage (applied to the substrate from 0 to -250V) on the $sp^3$ hybridized carbon fraction is examined by Raman spectroscopy and x-ray photoelectron spectroscopy (XPS) for C 1s core peak. For the first time, depth profile of C 1s, Si 2p, and O 1s XPS peaks for the deposited DLC film are obtained. DLC film is modeled as a multilayered structure. composing of surface, bulk, and interface. In addition, the x-ray reflectivity (XRR) is proposed as a method for estimating the density, surface roughness, and thickness of each layer constituting the DLC film. The estimated thickness of DLC film is in good agreement with the result obtained from the transmission electron microscope (TEM) measurement.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.574-577
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• 2001

GaN thin films on sapphire were grown by rf magnetron sputtering with ZnO buffer layer. The dependence of GaN film quality on ZnO buffer layer was investigated by X-ray diffraction(XRD). The improved film quality has been obtained by using thin ZnO buffer layer. Using Auger electron spectroscopy(AES), it was observed that the annealing process improved the GaN film quality. The surface roughness according to the annealing temperatures(700, 900, 1100$^{\circ}C$) were investigated by AFM(atomic force microscopy) and it was confirmed that the crystallization was improved by increasing the annealing temperature. Photoluminescence at 8K shows a near-band-edge peak at 3.2eV with no deep level emission.

• 한국진공학회지
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• 제4권S2호
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• pp.30-33
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• 1995

By using X-ray double crystal diffraction technique the multilayer structure composed of glass membrane, platinum film and $\alpha Al_2O_3$ substrate has been studied. It is found the stress is produced in the film by thermal mismatch within multilayer materials. The measuring results of thin film platinum resistors show that the stress were induce resistance change of device and different stress status will produce add resistance in different direction. Selecting proper glass material can make opposite stress in Pt film and opposite add resistance due to thermal mismatch. The reliability of Pt resistor has been improved with method of this stress compensation.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2003년도 연료전지심포지움 2003논문집
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• pp.83-88
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• 2003

PtRu alloy and $PtRu-WO_3$ nanocomposite thin-film electrodes for methanol electrooxidation were fabricated by means of a sputtering method. The structural and electrochemical properties of well-defined PtRu alloy thin-film electrodes were characterized using X-ray diffraction, Rutherford backscattering spectroscopy. X-ray photoelectron spectroscopy, and electrochemical measurements. The alloy thin-film electrodes were classified as follows: Pt-based and Ru-based alloy structure. Based on structural and electrochemical understanding of the PtRu alloy thin-film electrodes, the well-controlled physical and (electro)chemical properties of $PtRu-WO_3$, showed superior specific current to that of a nanosized PtRu alloy catalyst, The homogeneous dispersion of alloy catalyst and well-formed nanophase structure would lead to an excellent catalytic electrode reaction for high-performance fuel cells. In addition, the enhanced catalytic activity in nanocomposite electrode was found to be closely related to proton transfer in tungsten oxide using in-situ electrochemical transmittance measurement.

• 대한방사선기술학회지:방사선기술과학
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• 제22권1호
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• pp.49-53
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• 1999

To inquire its usefulness of the clinical application of intelligent replenishment system of automatic X-ray film processor based on film density, we processed the serial 300 sheets of radiographic film of chest [$14{\times}14"$, HR-C type] and bone [elbow & ankle($8{\times}10"$), skull($10{\times}12"$), hand & foot($11{\times}14"$), pelvis($14{\times}17"$), HR-G type, 68, 70, 77, 85 sheets respectively]. We analyzed the characteristic corves, relative speeds, average gradients and base plus fog densities every twenty five sheets. We also evaluated the developer and fixer replenishment volumes every that time. In the chest and bone radiograph two all, the characteristic curves were little change, and the relative speeds, average gradients and base plus fog densities were within the maximum control limits. The average developer replenishment volumes were about 43m1/sheet and 39m1/sheet respectively. It brings decreased results about 29% in comparison with the conventional replenishment system. In our experiences, we conclude that the intelligent replenishment system of automatic X-ray film processor based on film density maintains image quality consistently, decreases also the replenishment volumes. Therefore, this system will be resulted in economic and environmental effects, and solve problems of over and low replenishment volume.