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.

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.

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.

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.

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.

연금술과 연단술의 유사성 연구

이선우(Sunwoo Lee) 한국동서비교문학학회 2015 동서 비교문학저널 Vol.0 No.33

Alchemy (Western alchemy) and Lian Dan Shu (Chinese alchemy) have lots of similarities though they developed respectively at both ends of Asian Continent. Surveying their historical development aspect, we can find that they started from the fusion of various thoughts and technologies, changed to a skill for transmutation of materials, and finally resulted into the means of mental maturity. They have the common elements in their theories, too. At first, organicism is the common ideological foundation of alchemy and Lian Dan Shu. An alchemical motto, “as above so below” and a maxim of Lian Dan Shu, “heaven and man correspond each other (天人相應)” share the same world outlook. The homologous concepts between the components of each theory, such as, ‘chi (氣)’ and ‘prima materia’, ‘four elements’ and ‘five elements (五行)’ prove that these two theories was almost similar to each other. There is no difference we can actually recognize except the fact that the one pursed the transmutation of gold and the other sought to make jindan (The Golden Elixir, 金丹). Alchemy, which had been thought as a pseudo-science, depending on the development of Modern science which seeks after objectivity, was dramatically reappraised as a guide of ‘collective unconsciousness’ by Karl Gustav Jung. He thought that the alchemical opus was something resembling psychic processes expressed in pseudchemical language and alchemists projected their unconscious into materials with which they experimented. His ‘Individuation’ theory was established through his study of Lian Dan Shu.

원활한 갈등조정을 위한 필요조건 -경험으로부터의 교훈-

이선우 ( Sunwoo Lee ) 한국정책학회 2011 韓國政策學會報 Vol.20 No.3

이 연구는 현장에서의 실무적 경험을 근거로 갈등조정과정에 필요한 주요한 조건 일곱가지를 설명하고 그로부터 얻을 수 있는 교훈을 도출해 내고 있다. 통상적으로 교과서나 전문서적 등에서는 갈등조정프로세스와 각 프로세스 상 중요하게 다루어야 할 기술적인 부분들에 대해서는 자세히 그리고 다양한 차원에서 소개하고 있으며, 교육과정에서도 이부분들에 대한 훈련은 구체적이고 실습도 이루어진다. 그러나 실제 조정과정에서 반드시고려하여야 할 전제조건들에 대한 언급이나 교육훈련은 미흡하다. 일곱 가지 필요조건이란 사전조정과정, Groundrule 정하기, 조정대표 및 중립적 조정자의 선정과 조정자의 신뢰확보, 갈등조정위원회의 위상, 갈등당사자집단 상호간의 주장에 대한 정확한 이해, 합의안 도출을 위한 숙의적 방법의 활용, 합의과정에서의 조정대표들의 책임성 확보 및 조정자의 역할갈등 등이며, 이 연구에서는 일곱 가지 조건들에 대하여 설명한 후, 이어서각 조건들로부터 얻을 수 있는 교훈을 도출하고자 한다. This Research explains seven conditions for effective conflict mediation, and suggests lessons from field experiences. Books and training programs related to conflict relations or management usually introduce technical contents, such as rapport building, reflective listening, chunking or consensus building, in detail, which are very important in mediation process. However, those books and training programs are not specifically dealt with the above conditions. Seven conditions are pre-mediation process, groundrules, selection of mediators with trust and representatives of conflict parties, legal status of a conflict mediation committee, clarification of arguments by conflict parties, usage of deliberative method, responsibility guarantee of representatives of conflict parties. In conclusion, this research comes up with lessons from each condition.

딥러닝을 이용한 시계열 데이터의 이상 검출

이선우(Sunwoo Lee),양호준(Hojun Yang),이문형(Munhyung Lee),최정무(Jungmu Choi),박지훈(Jihoon Park),신혜정(Hyejung Shin),권장우(Jangwoo Kwon) 대한환경공학회 2020 대한환경공학회 학술발표논문집 Vol.2020 No.11

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.

멀티프로세서 임베디드 소프트웨어를 위한 컴포넌트 기반 설계 및 성능분석 방법

이선우 ( Sunwoo Lee ),정병관 ( Byung Kwan Jung ),유민수 ( Minsoo Ryu ) 한국정보처리학회 2008 한국정보처리학회 학술대회논문집 Vol.15 No.2

현재까지 소프트웨어 개발을 위한 많은 컴포넌트 기술들이 연구되어 왔다. 하지만 기존의 기술들은 멀티프로세서 환경에서 사용하기에 적합하지 못하다. 멀티프로세서 임베디드 소프트웨어를 구성 하는 다수의 쓰레드들이 병렬적으로 수행될 수 있고, 그로 인한 성능 문제 또한 고려되어야 하기 때문이다. 본 논문에서는 새로운 컴포넌트 모델과 태스크 모델, 그리고 소프트웨어 설계 과정을 제안한다. 그리고 컴포넌트 모델과 태스크 모델 사이의 변환 과정 및 병렬성 극대화를 위한 태스크 분할 과정을 소개하여, 최종적으로 성능분석이 가능한 멀티프로세서 임베디드 소프트웨어 개발 과정을 제시한다.