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CNT-confined reaction에 의한 탄화규소 나노튜브의 합성
노대호,김재수,변동진,양재웅,김나리,Rho Dae-Ho,Kim Jae-Soo,Byun Dong-Jin,Yang Jae-Woong,Kim Na-Ri 한국재료학회 2004 한국재료학회지 Vol.14 No.3
SiC nanotubes were synthesized by CNT-confined reaction. Evaporated SiO gas reacted with carbon nanotubes by VS growth mechanism. By confineded reaction, carbon nanotube was changed to SiC nanotube, and synthesized SiC nanotube was filled partly by the gas reaction in the nanotubes. SiC nanotube's mean diameters were not changed than carbon nanotubes because of means ratio of $CO_2$ and SiO gas was maintained evenly during the process. This result was same of data of simulation. By TEM observastion, SiC nanotube was filled by reaction of inner wall of CNT and SiO gas through the VS reactions. Converted SiC nanotube's compositions were revealed Si and C of 1: 1 ratios at all sites of nanotube by EDS.
노대호,김재수,변동진,양재웅,김나리 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.9
SiC nanorod has been synthesized directly on Si using CVD method. Ni was used for liquid catalyst during growth, and HMDS was used for source materials. Growth temperature and time effected grown nanorod’s diameter by growth rate. Deactivation was occurred at high source gas concentration. From the cross-sectional SEM image, SiC nanorod growth was divided two regions because of lateral VS growth effect. SiC nanorod was grown with uniaxial direction and highly crystalline phase.
신경망을 이용한 가공공정에서 코팅공구의 성능평가에 관한 연구
노대호,이흥국,박환서,유송민,신관수 경희대학교 산학협력기술연구원 2006 산학협력기술연구논문집 Vol.12 No.1
생산제조 공정의 편의 증대를 위한 가장 절박하고 저렴한 요구는 생산성 향상을 손쉽게 하는 것이다. 이것은 제조 사이클에서 생산율 증가와 손실감소를 달성함으로 실현할 수 있다. 이 화제에 가장 좋은 연구 분야는 공구 모니터링이다. 이것은 전통적인 생산자와 공구 제조사가 고등 기술 또는 재료기술에 관심을 갖게 하는 것이다. 공구수명 증가는 코팅된 공구와 많은 주의로 언하여 극적으로 향상되었고 공구조건 모니터링 평가방법에 노력이 집중되었다. 고속가공,고강도 물질의 가공은 공구수명 예측을 더 어렵게 만든다. 공구파괴가 일어나지 않게 하기위하여,주로 공구의 한계능력 이하로 사용 한다. 그런 까닭에, 만약 공구 수명 또는 파괴를 잘 예측 할 수 있다면 급격한 생산성 증가를 이룰 수 있다. 많은 연구자들은 가장 효과적인 공구 성능 저하 정보와 획득 방법 그리고 정보 처리에 관심을 두고 있다. 정보의 습득에 절삭력[1 -4],경향 [5,6],음향방출 CAE) 신호 [7],진동신호 [8],그리고 머신 비젼이 [9- 11]이용되고 있다. 가공하는 동안 얻은 정보의 처리방법에 임계치 표준 [1,3], 신경망[2,7, 8], 주파수 스팩트럼 분석 [4] 그리고 퍼지 분류법을 [5-8] 이용하고 있다. 코팅 기술은 공구수명 증가 에 따른 공구 성능 향상을 가져왔다. 공구 성능 향상을 위한 또 다른 접근은 코팅공구 사용 에 따른 성능 변화를 알아내는 것이다[1 2-14]. 2차 전단영역에서의 소성변형은 공구 마모제어 로 알 수 있다 [12]. 가공 최적조건은 코팅공구 와 초경공구 모두 드릴링에서 사용하여 최소 구멍 직경 편차와 표면 거칠기의 항으로 알 수 있다. 코팅공구의 flank 마모의 4에서 5분류 등급은 무감독 식과 self- organizing 인공신경망,adaptive res onance theory 2를 이용하여 발전되었다[13]. The key performance required in the manufacturing cutting tool was to enhance the tool life. Even though there had been lots of claims as for effectively assessing the performance of CVD coated cutting tool, few cases were reported to support them. A neural network methodology with supervised training algorithm was utilized to assess the performance evaluation. In order to assess the performance enhancement of the coated tool, conventional metal cutting process was selectively chosen. Cutting conditions including cutting speed, feed speed and depth of cut were selected as inputs parameters governing the relevant machining process. As for the performance assessment index, tool wear and process status variables were monitored. The tool wear due to the abrasive interaction between the tool and the workpiece was characterized. The neural network method was applied to train the machining and cutting tool conditions using the empirical data obtained during the process.
화상처리를 이용한 유연성디스크 가공 평면구간 측정에 관한 연구
노대호,박환서,이홍국,신관수,유송민,Roh, Dae-Ho,Park, Hwan-Seo,Lee, Hong-Guk,Shin, Kwan-Soo,Yoo, Song-Min 한국생산제조학회 2010 한국생산제조학회지 Vol.25 No.5
The goal of this study is to simplify the measurement process of the flat zone length produced by a flexible disk grinding system for the process automation. The image of workpiece in the grinding process is obtained, and the cutting speed and the feeding speed are controlled carefully to maximize the flat zone length. The gradient, the inflection point and the length of the line in the image are calculated, and the length is also measured by using a projector. Processing conditions and inversely proportional to flat zone length was changing. The flat zone length is estimated by Neural network algorithm considering the process conditions with the estimated error range as 0.06~3.61%, the Neural network algorithm for the grinding process estimation is found to be useful for building the process automation database.
노대호,김재수,변동진,이재훈,양재웅,김나리,Rho, Dae-Ho,Kim, Jae-Soo,Byun, Dong-Jin,Lee, Jae-Hoon,Yang, Jae-Woong,Kim, Na-Ri 한국재료학회 2005 한국재료학회지 Vol.15 No.3
[ $SiO_2$ ] nanowires were synthesized using the catalyst evaporation method. Grown nanowires had different shapes by kind of used metal catalyst. Mean diameters of grown $SiO_2$ nanowire were about 30 nm. The kind of catalysts affected microstructure of grown $SiO_2$ nanowire because of its typical growth reactions through the liquid state metal catalysts. Optical property were measured by photoluminescence spectroscopy. Relatively broad peak was obtained and mean peak positioned at 450 nm.
노대호,김재수,변동진,양재웅,김나리,Rho, Dae-Ho,Kim, Jae-Soo,Byun, Dong-Jin,Yang, Jae-Woong,Kim, Na-Ri 한국재료학회 2003 한국재료학회지 Vol.13 No.10
SiC nanowires were synthesized by carbothermal reduction using metal catalysts. Synthesized nanowires had mean diameters of 30∼50 nm and several $\mu\textrm{m}$ length. The kind of catalysts affects form of SiC nanowire because of difference of growth mechanisms. These differences were made by catalyst's physical property and relative activities to the source gas. Ni acted a conventional catalyst of VLS growth mechanism. But, Case of Fe, SiC nanowire was grown by stable VLS growth mechanism without relation of growth conditions. SiC nanowire was grown by two step growth model using Cr catalyst. Conversion ratios to the SiC nanowire were increased with growth conditions. Case of Cr, conversion ratio was about 45% that was higher than other catalyst used. This high conversion ratio was obtained by the addition VS growth to radial direction on the as-grown nanowires.
노대호,이홍국,박환서,유송민 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-
In order to improve the performance of the flexible disk grinding system for process automation, nonflat zone is analyzed. Process product profiles for various cutting speed, feed, depth of cut and disk engage angle are checked using projector in order to identify characteristic points corresponding to flat zone dimension. Flat zone dimension trends are correlated with various process conditions. The advantage of this process would be the facilitation of the conventional process condition in maximizing the product flat zone quality.
SLS(Solid-Liquid-Solid) 성장기구에 의한 탄화규소 나노튜브의 성장
노대호,김재수,변동진,양재웅,김나리,Rho Dae-Ho,Kim Jae-Soo,Byun Dong-Jin,Yang Jae-Woong,Kim Na-Ri 한국재료학회 2004 한국재료학회지 Vol.14 No.2
SiC nanotubes were synthesized by SLS growth mechanism using various metal catalysts. Synthesized nanotubes had mean diameters of 20~50 nm and several $\mu\textrm{m}$ length. The kind of catalysts affected microstructures of SiC nanotubes by different diffusion routes. These differences are attributed to catalysts' physical properties and relative activities to the graphite substrate. Fe acted as a good catalyst of SLS growth mechanism. But in case of Ni, SiC nanotubes grew slowly. Optical property was measured by photoluminescence measurement. Relatively broad peak was obtained and mean peak positioned at about 430 nm. This result was the same as other nanocrystalline SiC materials, but was different from the results of bulk SiC probably due to quantum confinement effect and defect in the grown SiC nanotube.
노대호,김재수,변동진,양재웅,김나리,Rho, Dae-Ho,Kim, Jae-Soo,Byun, Dong-Jin,Yang, Jae-Woong,Kim, Na-Ri 한국재료학회 2003 한국재료학회지 Vol.13 No.6
SiC nanorods have been grown on Si (100) substrate directly. Tetramethylsilane and Ni were used for SiC nanorod growth. After 3minute, SiC nanorod had grown by CVD. Growth regions ware divided by two regions with diameter. The First region consisted of thin SiC nanorods having below 10 nm diameter, but second region's diameter was 10∼50 nm. This appearance shows by reduction of growth rate. The effect of temperature and growth time was investigated by scanning electron microscopy. Growth temperature and time affected nanorod's diameter and morphology. With increasing growth time, nanorod's diameter increased because of the deactivation effect. But growth temperatures affected little. By TEM characterization, grown SiC nanorods consisted of the polycrystalline grain.
노대호,김재수,변동진,이재훈,양재웅,김나리,조성일,Rho Dae-Ho,Kim Jae-Soo,Byun Dong-Jin,Lee Jae-Hoon,Yang Jae-Woong,Kim Na-Ri,Cho Sung-Il 한국재료학회 2004 한국재료학회지 Vol.14 No.7
$SiO_2$ nanowires were synthesized using the vapor evaporation method. Grown nanowires had a different shapes by kind of substrates. Diameters and lengths of the nanowires increased with increasing growth temperature and time. Mean diameters and lengths of $SiO_2$ nanowire were different by kind of substrates. These variations were attributed to nanowire densities on the substrates. The kind of substrates affected microstructure and PL properties of grown nanowires. In case of $Al_{2}O_3$ and quartz substrates, additional $O_2$ were supported during growth stages, and made a nucleation site. Therefore relative narrow nanowire was grown on $Al_{2}O_3$ and quartz substrates. Optical property were measured by photoluminescence spectroscopy. Relatively broad peak was obtained and mean peak positioned at 450 and 420nm. however in case of quartz substrates, mean peak positioned at 370nm. These peak shift was contributed to the size and substrate effects.