• Radiation Oncology Journal
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• v.11 no.2
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• pp.449-454
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• 1993

The skin sparing effect associated with high energy x-ray or gamma ray beams may be reduce or lost under certain conditions of treatment. Current trends in using large fields. Shield carrying trays, compensating filters, and isocentric methods of treatment have posed problems of increased skin dose which sometimes become a limiting factor in giving adquate tumor doses. We used the shallow ion chamber to measure the phantom surface dose and the physical treatment variables for Co-60 gamma ray, 4MV and 10 MV x-ray beam. The dependence of percent surface dose on field sizes, atomic number of the shielding tray materials and its distance from the surface for 4, 10MV x-rays and Co-60 gamma ray is qualitatively similar. The use of 2 mm thick tin filter is recommended for situations where a low atomic number tray is introduced into the beam at distances less than 15 cm from the surface and with the large field sized for 4 MV x-ray beam. In case of Co-60 gamma ray, the lead glass tray is suitable for enhancement of skin sparing. Also, the filter distance should be as large as possible to achieve substantial skin sparing.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.12
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• pp.1048-1053
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• 2015

Ablative materials in a thermal protection system for atmospheric re-entry suffers from the most severe heat fluxes and temperatures, which induces surface recession in the thickness direction. In this paper, a 0.4MW arc-heated wind tunnel is operated to test for ablative materials, and a non-contact three-dimensional surface measuring system is used to evaluate the different surface characteristics of them. In particular, by postprocessing the three-dimensional image data, the surface roughness and recession of ablative materials can be calculated before and after the wind tunnel test. Moreover, the surface properties are analyzed quantitatively by comparing volume and mass losses of the test specimens.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.6
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• pp.298-304
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• 2009

The effect of the surface treatments on the high temperature properties of the Inconel 617, one of the promising candidate alloys for high temperature heat-transport system, has been studied. Various surface modification methods including a rapid thermal process(RTP), a hydrothermal treatment, and a physical vapor deposition($2{\mu}m$ thick TiAlN film by an arc discharge) were applied to the Inconel 617. The morphological and the structural properties of the surface-modified Inconel 617 samples after heat treatment at $1000^{\circ}C$ in the air were compared to find out whether inhomogeneous formation of $Cr_2O_3$ crust at the surface region was suppressed or not. TiAlN-coated Inconel 617 showed homogeneous microstructure and the lowest wear loss compared to bare, RTP- and hydrothermally-treated Inconel 617 by suppressing the $Cr_2O_3$ crust formation.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.516-516
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• 2013

Flexible Display를 제작하기 위해서는 유기소자를 보호하는 보호막이 필요하다. 유기소자는 산소 및 수분에 매우 취약하기 때문에 장수명을 확보하기 위해서는 추가적인 보호층이 필요하다. 본 논문에서는 이를 위해 Encapsulation 중 한 방법인 Barrier Film을 제작하고 그에 따른 광학적인 특성 및 수분 투습율을 조사하였다. Barrier film의 광학적 분석 방법으로는 XPS, SEM, AFM, Transmittance를 측정하였으며, XPS는 박막내의 화학적인 결합을 알기 위해서 사용되었고, SEM은 박막의 두께 및 박막내의 결함을 파악하고자 하였다. SEM을 통해 증착속도가 32.6 nm/m이라는 것을 관찰할 수 있었다. AFM을 통해 증착된 박막의 표면 거칠기를 파악하였다. Transmittance는 PET 기판을 사용하여 가시광 영역에서 80%이상의 투과도를 나타내었다. PECVD 장비를 사용하여 SiH4, NH3, N2가스를 사용하여 PET 필름 위에 박막을 증착하였으며, 유량을 10~400 sccm 내에서 변화시키고, RF Power는 각각 30~300 W 15분간 증착하였다. 제작된 보호막의 수분투습율은 $2{\times}10{_2}^{-2}g/m^2/day$ 이하의 값을 나타내었다.

• Journal of Korean Association for Spatial Structures
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• v.6 no.4 s.22
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• pp.73-80
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• 2006

It is an object of the present paper to investigate a electrochemical properties of Mg-based sacrificial anodes and the effect of calcium added from calcium chloride into magnesium on the melt protection during the melting. Electrochemical data will be correlated with processing control variables, and the microstructural change by the addition of CaCl2. Small addition of calcium into magnesium from CaCl2 imparts beneficial effect in electrochemical properties of Mg alloys, primarily, through microstructural modifications. In addition, the protection effect of the melts surface of Ca with low melting point modification is obtained by adding Ca not more than 0.6%.

• Journal of Convergence for Information Technology
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• v.11 no.12
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• pp.221-228
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• 2021

In this work, the post-treatment using organic acids during hair dyeing process was used to maintain hair color and to decrease hair damage. The effect of post-treatment using succinic acid and tartaric acid during hair dyeing process with cherry red and blue silver color on the persistence of hair color, tensile strength of hair, hair porosity, and surface characteristics of hair was investigated. After the repeated shampooing process, the experimental group with succinic acid and tartaric acid could more efficiently maintain the hair color than control group. The experimental group with succinic acid and tartaric acid could also increase the tensile strength of hair, decrease the hair porosity, and smoothen the hair surface, compared with control group. Particularly, tartaric acid was able to maintain the color of the dyed hair and protect the hair with higher efficiency than succinic acid.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.2
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• pp.106-112
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• 2010

In order to compete with other flat display devices such as Liquid Crystal Displays (LCDs) and organic light emitting diodes (OLEDs), Plasma Display Panels (PDPs) require to have high performances like high image quality, low power consumption and high speed driving. In this paper, Fe doped MgO protective layer was introduced for higher performance. Both the surface characteristics of the deposited thin films and the electro-optical properties of 4 inch test panels were investigated. It has been demonstrated experimentally that ac PDP with Fe doped MgO protective layer has lower discharge voltage than that of undoped MgO film, which corresponds to measured secondary electron emission coefficients. The crystallinity and surface roughness of thin films were determined by XRD patterns and AFM images. In addition, ac PDP with Fe doped MgO protective layer has improved address discharge time lag for high speed driving.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.109-109
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• 2018

Cr-Mo 합금강은 고온 환경 하에서 높은 크리이프 강도와 우수한 내식성 때문에 발전설비, 석유 화학, 그리고 해양산업과 같은 여러 산업분야에서 널리 사용되고 있다. 특히, Cr-Mo 강의 내식성은 합금 내 Cr 함량에 크게 의존한다. 이는 고온에서 Cr과 O가 화학적 반응을 일으킴에 따라 보호성의 Cr 산화스케일을 형성하기 때문이다. 그러나 화석연료를 사용하는 발전설비의 경우, $SO_2$가 포함된 강한 부식성의 연소 가스가 배출되며, 이에 노출된 금속의 표면에서는 산화와 황화가 동시에 발생한다. 황화스케일은 산화스케일에 비해 매우 빠르게 성장하며, 그 특성이 매우 취약하기 때문에 황화 환경에서 금속의 내식성 및 기계적 물성치는 보다 크게 저하된다. 따라서 본 연구에서는 화력 발전소의 증기발생용 튜브 재료인 9Cr-1MoVNb 강을 선정하였으며, $SO_2$ 가스 환경 하에서의 부식 및 기계적 물성치 저하 특성을 평가하고자 하였다. 본 연구에서 사용된 9Cr-1MoVNb강의 화학 성분 조성은 0.1 C, 0.38 Si, 0.46 Mn, 0.25 Ni, 8.38 Cr, 0.93 Mo, 0.18 V, 0.09 Nb, 그리고 나머지는 Fe이다. 부식시험은 가공된 미소시험편과 인장시험편을 전기열처리로에 장입한 후, $650^{\circ}C$에서 $N_2+O_2+O_2+SO_2$ 조성의 가스를 분당 50 CC로 흘려주었다. 제작된 시험편에 대한 부식거동은 무게 증가량, optical microscope, scanning electron microsope, 그리고 energy dispersive x-ray spectrum을 통해 평가하였다. 그리고 기계적 물성치 평가를 위한 인장시험은 분당 2mm 변위제어를 통해 실시하였다. 그 결과, 9Cr-1MoVNb 강은 $SO_2$ 가스 환경 하에서 비 보호적인 Fe-풍부상의 산화 스케일층이 두껍게 형성됨에 따라 열악한 내식성을 나타냈다. 그에 따라 기계적 물성치는 저하되는 경향을 나타내었다.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.315-329
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• 2010

Characteristics of thermophilic bacteria and secondary materials on the pyrrhotite surface were investigated by using scanning electron microscopy (SEM). The thermophilic bacteria from an acid hot spring in Japan were incubated with pyrrhotite at $42^{\circ}C$, $52^{\circ}C$, and $62^{\circ}C$ respectively. SEM analysis of the reacted pyrrhotite showed that indigenous rod-shaped bacteria ranging from $0.4{\times}1.5{\mu}m$ to $0.3{\times}11.9{\mu}m$ in size were attached to the pyrrhotite surface at these temperatures with formation of secondary materials. Extracellular polymer substances were formed on the bacterial surface. We suggest that these polymers functioned as a capsule protecting bacteria from the extreme environment. Secondary materials such as elemental sulfur, Fe-hydroxide, S-Fe and O-P-Fe compounds were found on the pyrrhotite surface.

• Tribology and Lubricants
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• v.30 no.6
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• pp.343-349
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• 2014

Currently, in order to resist the scratching of the fuel rod surface while fabricating the fuel assembly of the light-water nuclear reactor, we use a solution of nitrocellulose, an explosive material, as a dry lubricant along with its solvent. However, the demand for developing safe and harmless aqueous alternative materials for environment-conservation and field-worker safety has increased. In this study, we demonstrate the preparation of a novel aqueous resin composite using a formulation of aqueous polymeric resin, alcoholic solvent, and water. Subsequently, we characterize this composite on the basis of hardness, adhesive property, and water solubility using plates similar to the fuel rod material. The insertion test of a fuel rod coated with the YS-3 composite shows load values of $18.8-20.5kg/cm^2$, which is comparable with $18.8-20.5kg/cm^2$ of the nitrocellulose coating agent. In addition, the depth and width of longitudinal scratches caused by the YS-3 composite test are 50% higher than those of the standard. We can develop a harmless and safe aqueous dry lubricant to replace the existing NC products through field testing of 264 pieces of fuel rods, after producing 350 kg of the YS-3 prototype. The scratch test for the rod surface showed that weight of chip of YS-3 prototype was smaller than that of NC before and after solvent treatment, indicating the properties of YS-3 prototype was comparable to the counterpart.