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마그네슘환원에 의한 C/N 조성제어 초미립 TiC<sub>x</sub>N<sub>y</sub> 분말 합성
이동원,김병기,윤중열,유지훈,김용진,Lee, Dong-Won,Kim, Byoung-Kee,Yun, Jung-Yeul,Yu, Ji-Hoon,Kim, Yong-Jin 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.2
The ultrafine titanium carbonitride ($TiC_xN_y$) particles below 100 nm in mean size, including various carbon and nitrogen contents (x=0.55~0.9, y=0.1~0.5), were successfully synthesized by new Mg-thermal reduction process. Nanostructured sub-stoichiometric titanium carbide ($TiC_x$) particles were initially produced by the magnesium reduction of gaseous $TiCl_4+x/2C_2Cl_4$ at $890^{\circ}C$ and post heat treatments in vacuum were performed for 2 hrs to remove residual magnesium and magnesium chloride mixed with $TiC_x$. Finally, well C/N-controled $TiC_xN_y$ phases were successfully produced by nitrification heat treatment under normal $N_2$ gas atmosphere at $1150^{\circ}C$ for 2 hrs. The values of purity, mean particle size and oxygen content of produced particles were about 99.3%, 100 nm and 0.2 wt.%, respectively.
이동원,박근태,임태수,이혜문,유지훈,Lee, Dong-Won,Park, Geun-Tae,Lim, Tae-Soo,Lee, Hye-Moon,Yu, Ji-Hun 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.4
Zr-Ti alloy powders were successfully synthesized by magnesium thermal reduction of metal chlorides. The evaporated and mixed gasses of $ZrCl_4+TiCl_4$ were injected to liquid magnesium and the chloride components were reduced by magnesium leading to the formation of $MgCl_2$. The released Zr and Ti atoms were then condensed to particle forms inside the mixture of liquid magnesium and magnesium chloride, which could be dissolved fully in post process by 1~5% HCl solution at room temperature. By the fraction-control of individually injected $ZrCl_4$ and $TiCl_4$ gasses, the final compositions of produced alloy powders were changed in the ranges of Zr-0 wt.%~20 wt.%Ti and their purity and particle size were about 99.4% and the level of several micrometers, respectively.
이동원,최준환,임태수,김용진,Lee Dong-Won,Choi Joon-Hwan,Lim Tae-Soo,Kim Yong-Jin 한국분말야금학회 2006 한국분말재료학회지 (KPMI) Vol.13 No.3
The nanostructured cerium oxide powders were synthesized by spray thermal decomposition process for the use as the raw materials of resistive oxygen sensor. The synthesis routes consisted of 1) spray drying of water based organic solution made from cerium nitrate hydrate ($Ce(NO_3){_3}6H_2O$) and 2) heat treatment of spray dried precursor powders at $400^{\circ}C$ in air atmosphere to remove the volatile components and identically to oxidize the cerium component. The produced powders have shown the loose structure agglomerated with extremely fine cerium oxide particles with about 15 nm and very high specific surface area ($110m^2/g$). The oxygen sensitivity, n ($Log{\propto}Log (P_{O2}/P^o)^{-n}$ and the response time, $t_{90}$ measured at $600^{\circ}C$ in the sample sintered at $1000^{\circ}C$, were about 0.25 and 3 seconds, respectively, which had much higher performances than those known in micron or $100{\sim}200nm$ sized sensors.
이동원,김병철,Lee, Dong Won,Kim, Byungcheul 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.8
The rectified voltage supplied to LED lamp is used in load and then the surplus voltage can be produced in LED lighting. In this case, LED lighting is proposed that can recyclable the excess voltage to supply power to the controller.
이동원,허상현,염종택,왕제필,Lee, Dong-Won,Heo, Sang-Hyun,Yeom, Jong-Taek,Wang, Jei-Pil 한국분말야금학회 2013 한국분말재료학회지 (KPMI) Vol.20 No.1
The extraction of metallic pure vanadium powder from raw oxide has been tried by Mg-reduction. In first stage, $V_2O_5$ powders as initial raw material was reduced by hydrogen gas into $V_2O_3$ phase. $V_2O_3$ powder was reduced in next stage by magnesium gas at 1,073K for 24 hours. After reduction reaction, the MgO component mixed with reduced vanadium powder were dissolved and removed fully in 10% HCl solution for 5 hours at room temperature. The oxygen content and particle size of finally produced vanadium powders were 0.84 wt% and 1 ${\mu}m$, respectively
이동원,김부윤,정영우,Lee, Dong Won,Kim, Boo Yoon,Chung, Young Woo 영남수학회 2016 East Asian mathematical journal Vol.32 No.2
There are three subjects in the study. First, after investigating the development process of the method of infinite descent and the reduction to absurdity, we prove them to be equivalent each other. Second, we apply the method of infinite descent to some problems in textbook and compare it with the reduction to absurdity. Finally, we discuss on teaching proofs with the method of infinite descent.
SHS 공정에 의해 제조된 Mo<sub>x</sub>W<sub>1-x</sub>Si<sub>2</sub> 발열체의 열화메커니즘
이동원,이상헌,김용남,이성철,구상모,오종민,Lee, Dong-Won,Lee, Sang-Hun,Kim, Yong-Nam,Lee, Sung-Chul,Koo, Sang-Mo,Oh, Jong-Min 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.10
The degradation mechanism of $Mo_xW_{1-x}Si_2$ ultrahigh-temperature heating elements fabricated by self-propagating high-temperature synthesiswas investigated. The $Mo_xW_{1-x}Si_2$ specimens (with and without post-annealing) were subjected to ADTs (accelerated degradation tests) at temperatures up to $1,700^{\circ}C$ at heating rates of 3, 4, 5, 7, and $14^{\circ}C/min$. The surface loads of all the specimen heaters were increased with the increase in the target temperature. For the $Mo_xW_{1-x}Si_2$ specimens without annealing, many pores and secondary-phase particles were observed in the microstructure; the surface load increased to $23.9W/cm^2$ at $1,700^{\circ}C$, while the bending strength drastically reduced to 242 MPa. In contrast, the $Mo_xW_{1-x}Si_2$ specimens after post-annealing retained $single-Mo_xW_{1-x}Si_2$ phases and showed superior durability after the ADT. Consequently, it is thought that the formation of microcracks and coarse secondary phases during the ADT are the main causes for the degraded performance of the $Mo_xW_{1-x}Si_2$ heating elements without post-annealing.
특집 : 극한환경재료기술 - 지르코늄 금속의 제조 및 개발 동향
이동원,Lee, Dong-Won 재료연구소 2010 機械와 材料 Vol.21 No.4
지르코늄은 지구상에 9번째로 풍부한 금속소재이며, 어느 금속소재 보다는 우수한 내식성을 보유하고 있으며 기계적 특성 및 열전도도가 기존의 SUS 계 및 Ti 계 소재와 유사한 특징이 있기 때문에, 핸드폰, 보철재료, 합성섬유, 석유화학 공업용 부품에 널리 사용되고 있다. 지르코늄 부품제조를 위해서는 무엇보다도 초기 금속원자재의 생산기술 확보가 선행되어야 한다. 즉, 초기 금속원자재인 지르코늄 금속스폰지의 제조기술의 확보가 필요하다. 본 고에서는 지르코늄 금속의 용도, 산업동향, 지르코늄 스폰지 제조기술 및 최근 연구개발 동향에 대해 간략히 소개하였다.