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저가형 용사피막형성법 이용 태양열 집열판 표면 처리에 관한 연구
김부안(Kim Bu-Ahn),최광환(Choi Kwang-Hwan),노상훈(Roh Sang-Hoon) 한국태양에너지학회 2006 한국태양에너지학회 논문집 Vol.26 No.3
A solar collector surface coated with a low emission material is still imported from other developed countries expensively. Thus it is very significant to develop a new coating method with a cheap alternative coating material instead of the imported high-cost collector surface. A thermal spray method was adopted to coat a cheap Titania on a copper plate. Generally, a new coating on the copper plate was conducted successfully by selecting a proper ratio of carbon and acetylene. By measuring an absorption rate of solar and heat emission rate, all the plate types gained a high absorption rate of 98% approximately, more or less, but all of the types still have a high emission. Finally it was clear that more research is needed to advance the coated-plate to subdue the high emission from the hot plate surface and the higher the Titania’s proportion is, the lower the emission is on the surface.
김부안(BU-AHN KIM),문창권(CHANG-KWON MOON) 한국해양공학회 2001 韓國海洋工學會誌 Vol.15 No.2
The fracture toughness of ceramics can be measure by such various methods as DT (double torsion), CN (chevron notch) etc. But, the application of these methods to the engineering ceramics is very difficult because of its very high hardness. So, IF (indentation fracture) method is generally used for the evaluation of fracture toughness of ceramics. The Median crack induced by the sharp Vickers indenter W1S compared with the detected AE (acoustic emission) signal. On the silicon nitride ceramics, the AE test results agree fairly well with the median crack occurance and growth process. But, on the alumina, very many complicated crack signals were detected besides median crack. It can be considered that the IF methods must be used in limited engineering ceramics materials.
염수환경에서 탄소섬유/에폭시 복합재료의 내구성에 미치는 나노입자의 영향
김부안(Bu-Ahn Kim),문창권(Chang-Kwon Moon) 한국해양공학회 2014 韓國海洋工學會誌 Vol.28 No.1
This study was conducted to investigate the durability of carbon fiber/epoxy composites (CFRP) in a saline water environment. The carbon fiber/epoxy composites were modified to use nanoparticles such as carbon nanotubes and titanum oxide. These hybrid composites were exposed to a saline water envrionment for a certain period. The weight gain according to the immersion time, a quasi-static tensile test, and micro-graphic characterization were used to investigate the samples exposed to the saline water environment. The weight gains increased with increasing immersion time. The weight gains of the hybrid composites were lower than that for pure CFRP throughout the entire immersion time. The tensile strengths decreased with increasing immersion time. The tensile strengths of the hybrid composites were higher than that of the pure CFRP throughout the entire immersion time. The pure CFRP was observed to be more degraded than hybrid composites in the saline water environment. Therefore, it was concluded that the addition of nanoparticles to CFRP could lead to improved durability in a saline water environment.
김부안(Bu Ahn Kim),남기우(Ki Woo Nam),조문호(Mun Ho Cho) 한국해양공학회 1999 韓國海洋工學會誌 Vol.13 No.1
67Ni-22Cr-10Al-1Y and ZrO₂-8Y₂O₃ were coated on the substrate surface of STS304 and Al2024 by the plasma spraying method. The adhesion of the films varies depending on the substrates and the laminating method. In the case of STS304, the cracks were observed at thermal shock temperature difference △T of 900℃ in the non functionally gradient material(NFGM) and at 1100℃ in the functionally gradient material(FGM). The film adhesion of the FGM is better than that of the NFGM in STS304.<br/> The cumulative AE count of the FGM of STS304 increased continuously at the bending test. But the NFGM of STS304 showed discontinuity of the AE count. The total AE count for the FGM of STS304 decreased as the number of thermal shock increased, and this tendency was evident as the thermal shock temperature difference increased.
Y₃Al₅O<SUB>12</SUB> 첨가가 질화규소 세라믹스 제조 및 그 기계적 특성에 미치는 영향
노상훈(SANG-HOON NOH),김부안(BU-AHN KIM),문창권(CHANG-KWON MOON),정해용(HAE-YONG JEONG),서원찬(WON-CHAN SEO),윤한기(HAN-KI YOON) 한국해양공학회 2007 韓國海洋工學會誌 Vol.21 No.6
In the present work, silicon nitride was fabricated with Y₃Al?O12 as a sintering additive and its mechanical properties were investigated. Silicon nitride with 3, 5, and 7 wt% of Y₃Al?O12 was prepared and sintered by a Hot Pressing (HP) technique at 1750 and 1800 ℃ for 2h. The process was performed under different process pressures of 30 and 45 ㎫. Mechanical properties (density, strength, hardness, and fracture toughness) were investigated as a function of the Y₃Al?O12 content in Si₃N₄. Si₃N₄- Y₃Al?O12 ceramics showing similar mechanical properties compared with Si₃N₄-Y₂O₃-Al₂O₃ ceramics. But its high temperatures strength was considerably higher than that of Si₃N₄-Y₂O₃-Al₂O₃ ceramics.
탄소섬유강화 에폭시수지의 기계적 성질에 미치는 나노입자크기의 영향
문창권(Chang-Kwon Moon),김부안(Bu-Ahn Kim) 한국해양공학회 2015 韓國海洋工學會誌 Vol.29 No.2
TiO₂ nanoparticles can be used to improve the performance of carbon fiber-reinforced epoxy resin composites. In this study, the effect of the size of TiO₂ nanoparticles on the mechanical properties of carbon fiber-reinforced epoxy resin composites was investigated. The size of the TiO₂ nanoparticles was easily controlled using heat treatment. The size of the TiO₂ nanoparticles for this study were20nm, 100nm, and 200nm. Three types of carbon fibers with different diameters were also used in this study. The carbon fiber-reinforced epoxy resin composites with 20-nm TiO₂ powder showed the highest tensile strength compared to the other types of CFRP, regardless of the fiber maker or fiber diameter. The size of the TiO₂ powder and the diameter of the carbon fiber strongly affected the interfacial properties of all kinds of CFRP in this study.
김고운(Go-Un Kim),문창권(Chang-Kwon Moon),윤한기(Han-Ki Yoon),김부안(Bu-Ahn Kim) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
In this study, two different Al2O3 ceramics were prepared containing 15 wt% and 30 wt% of SiC nanoparticles. Surface crack was made at the center of specimen by vickers indentation. Crack healing behavior of Al2O3 ceramics was investigated by changing the loads of SiC nanoparticles and iterative crack-heat treatment process. The test samples were characterized by three-point bend flexural tests to evaluate their mechanical properties. The morphological changes were studied by scanning electron microscopy(SEM). The results indicated that : 1) The crack healing ability of the Al2O3 ceramics with 30 wt% of SiC nanoparticles were much higher than that of the Al2O3 ceramics with 15 wt% of SiC nanoparticles. 2) The cycle of indentation and treatment process revealed that the cracks of the Al2O3 ceramics were completely healed only 24.5N of vickers indentation load applied. 4) The SEM images showed that the median cracks were completely disappear due to the oxidation reaction.
문창권(Chang-Kwon Moon),김부안(Bu-Ahn Kim) 한국해양공학회 2013 韓國海洋工學會誌 Vol.27 No.2
In this study, the crack healing effects of Al₂O₃ ceramics based on the heat treatment conditions were investigated. The influence of the additive amounts of SiC nanoparticles and the cycling process of indentation-heat treatment on the crack healing effect of Al₂O₃ ceramics were also examined. Three-point bending tests were carried out and the morphological changes in the fracture surface were observed by using FE-SEM. As a result, heat-treated samples in a vacuum or air atmosphere showed improved bending strengths compared to un-heat treated samples. This means that cracked specimens can be healed by heat treatment in a vacuum or air atmosphere. The crack healing effect of Al₂O₃ ceramics that were heat treated in an air atmosphere was much higher than that of those heat treated in a vacuum. After heat treatment, the Al₂O₃ ceramics with 30 wt% SiC nanoparticles showed a higher bending strength than those with 15 wt% SiC. The cyclic indentation and heat treatment did not remarkably affect the crack healing effect. The SEM images showed that the median crack, indenter mark on the surface, and pores in the fracture surface of a specimen almost disappeared after being heat treated in an air atmosphere.