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강영권,이종무,최상욱,Gang, Yeong-Gwon,Lee, Jong-Mu,Choe, Sang-Uk 한국재료학회 1999 한국재료학회지 Vol.9 No.8
Ta/TaN 다층피막구조는 경도는 떨어지지만 연성이 큰 Ta 막과 취성을 가지며 경도가 높은 TaN 막을 교대로 반복하여 만든 다층구조로서 경도와 연성의 장점이 잘 조화되어 높은 인성을 나타낼 것으로 기대된다. 본 연구에서는 고속도강 기판위에 Ta/TaN 복합다층피막과 compositional gradient Ta-TaN 막을 각각 반응성 스퍼터링에 의하여 증착하고 열처리에 따른 경도 및 접착성을 조사하였다. $N_2$/Ar 유량비가 0.4일 때 결정성이 가장 우수한 TaN 막이 얻어지며, Ta/TaN 복합다층피막의 경도 및 스크래치 테스트 결과도 가장 우수하였다. 또한 Ta/TaN 복합다층피막 증착후의 어닐링 처리 시 어닐링 온도가 증가할수록 피막의 경도와 접착성이 악화되었으며, compositional modulation wavelength가 감소함에 따라 Ta/TaN 복합다층피막의 경도는 증가하지만 접착성은 wavelength에 대한 의존성이 약하게 나타났다. 그리고 compositional gradient Ta-TaN 막 증착후의 어닐링 처리 시 경도와 스크래치 테스트 값은 각각 20$0^{\circ}C$와 40$0^{\circ}C$에서 최대값을 나타내었다. The Ta/TaN multilayer structure with repeating layers of a poly-crystalline Ta layer of high ductility and a TaN layer of high hardness is expected to exhibit toughness. This paper reports the results on the hardness and the adhesion strength of Ta/TaN multilayers and compositional gradient Ta/TaN layers deposited on the high speed steel substrate by reactive sputtering as a function of annealing temperature. The TaN film deposited with the $N_2$/Ar ratio of 0.4 in the reactive sputtering process exhibits the highest crystallinity, and the highest hardness and the results of scratch test of the Ta/TaN multilayers. The hardness and adhesion strength of the Ta/TaN multilayers becomes deteriorated with increasing the annealing temperature in the heat treatment right after depositing the layers. Therefore, post-annealing treatments are not desirable in the case of the Ta/TaN multilayers from the standpoint of mechanical properties. Also the hardness of Ta/TaN multilayers increases with decreasing the compositional modulation wavelength, but the adhesion property of the layers is nearly independent of the wavelength. On the other hand, the compositional gradient Ta/TaN film exhibits the highest hardness and the value of scratch test for the post-annealing temperatures of 20$0^{\circ}C$ and 40$0^{\circ}C$, respectively. This tendency of the compositional gradient Ta/TaN films differs from that of the Ta/TaN multilayers.
강영권 東洋大學校 産業技術硏究所 2002 東洋大學校 産業技術硏究所 論文集 Vol.4 No.1
This study examines short-term returns on IPOs(initial public offerings) of 41 samples companies registered in KOSDAQ. If any returns are found, this study analyzes the reasons. As a result, this finds that IPOs from venture companies have shown excess returns during the first 3 or 4 days after initial offering.
강영권,안예진,김민선,김봉기 한국섬유공학회 2018 Fibers and polymers Vol.19 No.6
Although thermally conductive composites that can efficiently dissipate the heat generated from electronic devices are in high demand, most neat polymers used as matrix materials are problematic because they have poor thermal conductivities. The low thermal conductivity of polymeric materials is caused by structural defects; therefore, it can be improved by increasing the orientational regularity of the polymer chains. Here, main-chain liquid crystalline polymers (LCPs) were designed and synthesized to investigate the effects of liquid crystallinity-induced structural regularity on the thermal conductivity of the polymers. In addition, an in-situ polymerization method was devised for commercial applicability, and the thermal conductivity of the obtained polymer was compared to that of a conventionally polymerized polymer having the same structure. The designed polymers exhibited thermotropic liquid crystalline characteristics, and the polymer with longer spacers between the rigid segments showed relatively higher thermal conductivity exceeding 0.5 W·m-1· K-1 after sample preparation by injection molding. In addition, X-ray diffraction analysis revealed that the differences in the thermal conductivity, depending on the molding temperature during specimen preparation, were caused by variations in chain orientation within the same polymer. Based on the obtained results, it was concluded that LCPs are strong candidate matrix materials for thermally conductive composites; the suggested in-situ polymerization method could be applied practically to the polymerization of polyester-type LCPs.