APS로 표면 처리한 Fe 나노 입자 촉매를 이용한 CNT의 직경제어

이선우,Lee, Sunwoo 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.6

Diameter controlled carbon nanotubes (CNTs) were grown using surface modified iron nano-particle catalysts with aminpropyltriethoxysilane (APS). Iron nano-particles were synthesized by thermal decomposition of iron pentacarbonyl-oleic acid complex. Subsequently, APS modification was done using the iron nano-particles synthesized. Agglomeration of the iron nano-particles during the CNT growth process was effectively prevented by the surface modification of nano-particles with the APS. APS plays as a linker material between Fe nano-particles and $SiO_2$ substrate resulting in blocking the migration of nano-particles. APS also formed siliceous material covering the iron nano-particles that prevented the agglomeration of iron nano-particles at the early stages of the CNT growth. Therefore we could obtain the diameter controlled CNTs by blocking agglomeration of the iron nano-particles.

CNT/PVDF 압전 복합막의 제작과 전기적 특성

이선우,정낙천,Lee, Sunwoo,Jung, Nak-Chun 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.8

The carbon nanotube / poly-vinylidene fluoride (CNT/PVDF) composite films for the nano-generator devices were fabricated by spray coating method using the CNT/PVDF solution, which was prepared by adding PVDF pellets into the CNT dispersed N-Methyl-2-pyrroli-done (NMP) solution. The flexible CNT/PVDF composite films were investigated by the scanning electron microscopy, which revealed that the CNTs were uniformly dispersed in the PVDF matrix and thickness of the films was approximately $20{\mu}m$. Fourier transform infra-red spectra were used to investigate crystal structure of the as-spray-coated CNT/PVDF films, and we found that they revealed extremely large portion of the ${\beta}$ phase PVDF. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the resistance didn't show any saturation effect in the CNT concentration range of 0~4 wt%. Finally, the resulting nano-generator devices revealed reasonable current output after given mechanical stress.

스프레이 코팅법으로 제조된 CNT/PVDF 압전 복합막의 자기분극 메커니즘

이선우,Lee, Sunwoo 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.7

Carbon nanotubes (CNT) / polyvinylidene fluoride (PVDF) piezoelectric composite films for nanogenerator devices were fabricated by spray coating method. When the CNT/PVDF mixture solution passes through the spray nozzle with small diameter by the compressed nitrogen gas, electric charges are generated in the liquid by a triboelectric effect. Then randomly distributed ${\beta}$ phase PVDF film could be re-oriented by the electric field resulting from the accumulated electrical charges, and might be resulted in extremely one-directionally aligned ${\beta}$ phase PVDF film without additional electric field for poling. X-ray diffraction patterns were used to investigate crystal structure of the CNT/PVDF composite films. It was confirmed that they revealed extremely large portion of the ${\beta}$ phase PVDF crystalline in the film. Therefore we could obtain the poled CNT/PVDF piezoelectric composite films by the spray coating method without additional poling process.

머신 비전 기반 당구공 검출

이선우,허헌,SunWoo Lee,Heon Huh 한국인터넷방송통신학회 2024 한국인터넷방송통신학회 논문지 Vol.24 No.2

Since the outbreak of COVID-19, there has been a surge in sports conducted through online platforms due to the increase in remote and non-contact activities. Billiards, being suitable for online platforms, has received much attention, leading to research on detecting the position and trajectory of balls. In this paper, we propose a new method utilizing machine vision to detect the position of the balls accurately. The proposed method detects the outline of the ball using the Canny edge detection and then employs simple correlation to determine its position. This correlation-based approach offers satisfactory system performance and is easily applicable in practical systems due to its low implementation complexity and robustness to noise.

소수성 CNT/PVDF 복합막에서 CNT의 분산과 전도성의 관계

이선우,Lee, Sunwoo 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.7

In this paper, we investigated the relations between dispersion of CNTs (carbon nanotubes) and electrical conductivity in the CNT/PVDF (polyvinylidene fluoride) composite film. By adding hydrophobic CNTs as filler into the PVDF matrix, we fabricated hydrophobic and electrically conducting polymer coating film. Dispersion of CNTs in the CNT/PVDF composite film plays a significant role in terms of electrical conductivity and wetting property. Spray coating method was used to form the CNT/PVDF composite films by injecting the dispersed CNTs in the PVDF solution with different weight ratios from 0.7 wt% to 7 wt%. We investigated the electrical properties and contact angles of the CNT/PVDF composite films with the CNT concentration. Finally we discussed the conducting mechanism and feasibility of the CNT/PVDF composite film for the conducting polymer films.

RESRAD-RECYCLE 전산코드를 활용한 금속폐기물 내 우라늄 자체처분 허용농도 예비 평가

이선우,홍정환,박정석,김광표,SunWoo Lee,JungHwan Hong,JungSuk Park,KwangPyo Kim 한국방사선산업학회 2023 방사선산업학회지 Vol.17 No.4

The clearance level by nuclide is announced by the Nuclear Safety and Security Commission. However, the clearance level of uranium existing in nature has not been announced, and research is needed. Therefore, the purpose of this study was to evaluate the clearance level of uranium nuclides appropriate to domestic conditions preliminary. For this purpose, this study selected major processes for recycling metal wastes and analyzed the exposure scenarios and major input factors by investigating the characteristics of each process. Then, the radiation dose to the general public and workers was evaluated according to the selected scenarios. Finally, the results of the radiation dose per unit radioactivity for each scenario were analyzed to derive the clearance level of uranium in metal waste. The results of the radiation dose assessment for both the general public and workers per unit radioactivity of uranium isotopes were shown to meet the allowable dose (individual dose of 10 µSv y^-1 and collective dose of 1 Man-Sv y^-1) regulated by the Nuclear Safety and Security Commission. The most conservative scenarios for volumetric and surface contamination were evaluated for the handling of the slag generated after the melting of the metal waste and the direct reuse of the contaminated metal waste into the building without further disposal. For each of these scenarios, the radioactivity concentration by uranium isotope was calculated, and the clearance level of uranium in metal waste was calculated through the radioactivity ratio by enrichment. The results of this study can be used as a basic data for defining the clearance level of uranium-contaminated radioactive waste.

병렬로 접속된 저항체에서 저항온도계수의 거동

이선우,Lee, Sunwoo 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.2

In this paper, we discuss the fabrication of metal alloy resistors. We connected them in parallel to estimate their resistance and temperature coefficient of resistance (TCR). The fabricated resistors have different resistances, 5 and $10{\Omega}$ and different TCRs, 50 and $200ppm/^{\circ}C$. Each resistor was confirmed to have the correct atomic composition through the use of energy dispersive X-ray (EDX). The resistors' electrical properties were confirmed by measuring resistance and TCR. The resistance and TCR of the resistors connected in parallel were estimated through the increase in resistance due to the increase in temperature, and were compared with the measured values. We are confident that this TCR estimation technique, which uses the increase in resistance due to temperature, will be very useful in designing and fabricating resistors with low and stable TCR.

의료의사결정에서 철학교육의 활용

이선우(Sunwoo Lee),남승민(Seungmin Nam) 이화여자대학교 생명의료법연구소 2023 Asia Pacific Journal of Health Law & Ethics Vol.17 No.1

암모니아 식각 가스 도입에 의한 고순도 탄소나노튜브의 합성

이선우(Sunwoo Lee),이붕주(Boong-Joo Lee) 대한전기학회 2013 전기학회논문지 Vol.62 No.6

Multi-walled carbon nanotubes were synthesized on Ni catalyst using thermal chemical vapor deposition. By introducing ammonia gas during the CNT synthesis process, clean and vertically aligned CNTs without impurities could be prepared. As the ammonia gas increased a partial pressure of hydrogen in the mixed gas during the CNT synthesis process, we could control the CNT synthesis rate appropriately. As the ammonia gas has an etching ability, amorphous carbon species covering the catalyst particles were effectively removed. Therefore catalyst particles could maintain their catalytic state actively during the synthesis process. Finally, we could obtain clean and vertically aligned CNTs by introducing NH₃ gas during the CNT synthesis process.

자가 치유 이온전도체 및 전자소자에서의 응용

이선우(Sunwoo Lee),이해승(Haeseung Lee),강지형(Jiheong Kang) 한국고분자학회 2021 고분자 과학과 기술 Vol.32 No.4