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집속이온빔을 이용한 탄소나노튜브 팁의 조작 및 성능평가
윤여환(Yeo-Hwan Yoon),신영현(Young-Hyun Shin),한창수(Chang-Soo Han) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
We report the structural modification of carbon nanotube (CNT) tip for Atomic force microscopy (AFM) based on ion beam irradiation. In general, CNT tip assembled by dielectrophoresis would often have non-vertical angle, very crooked shape or too lengthy one. Therefore, these tips should be modified to the appropriate shape to use as an AFM tip. We found that the ion beam could contribute to merge the bundled CNTs, to make the CNT diameter uniform as well as to make the wavy shape of CNT straight. In addition, we could cut the free-standing CNT on a Si tip using focused ion beam(FIB). We measured anodic aluminum oxide sample and trench structure to estimate the performance of FIB-modified tip and compared with those of conventional Si tip. We demonstrate that FIB modified tip in non contact mode had superior characteristics than conventional tip in the respects of wear, image resolution and sidewall measurement.
대식세포에서 수련환(茱連丸) 물추출물의 항염증작용에 관한 연구
윤여환 ( Yeo Hwan Yoon ),김성배 ( Sung Bae Kim ),강옥화 ( Ok Hwa Kang ),문수현 ( Su Hyun Mun ),서윤수 ( Yun Soo Seo ),양다운 ( Da Wun Yang ),강다혜 ( Da Hye Kang ),위경 ( Gyeong Wi ),임재수 ( Jae Soo Lim ),김마룡 ( Ma Ryong Kim ) 대한본초학회 2014 大韓本草學會誌 Vol.29 No.6
Objectives : Suryeon-hwan (SRH) exhibits potent anti-inflammatory activity with an unknown mechanism. However, there has been a lack of studies regarding the effects of SRH on the inflammatory activities and effector inflammatory disease mechanism about macrophage before is not known. So, the investigation focused on whether SRH inhibited nitric oxide (NO) and prostaglandin E2 (PGE2) productions, as well as the expressions of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), and mitogen-activated protein kinases (MAPKs) in LPS-stimulated RAW 264.7 cells. Methods : Cells were treated with 200 ng/mL of LPS 30 min prior to the addition of SRH. Cell viability was measured by MTS assay. The production of nitric oxide (NO) was determined by reacting cultured medium with Griess reagent. The content of level of cytokines (PGE, IL-6) in media from LPS-stimulated Raw 264.7 cells was analyed by ELISA kit. The expression of COX-2, iNOS and MAPKs was investigated by Western blot, RT-PCR. Results : We found that SRH inhibited LPS-induced NO, PGE2 and IL-6 productions as well as the expressions of iNOS and COX-2. Furthermore, SRH suppressed the LPS-induced phosphorylation of MAPK and extracellular signal-regulated kinase 1/2 (ERK 1/2) activation. Conclusions : These results suggest that SRH has inhibitory effects on LPS-induced PGE2, NO, and IL-6 production, as well as the expressions of iNOS and COX-2 in the murine macrophage. These inhibitory effects occur through blockades on the phosphorylation of MAPKs following activation.
편광 및 웨이블릿 변환을 이용한 도로 표면 상태의 화상 인식
임성한(Lim Sung Han),류승기(Ryu Seung Ki),윤여환(Yoon Yeo Hwan) 대한토목학회 2007 대한토목학회논문집 D Vol.27 No.4D
눈, 비, 먼지, 빛, 그림자 등 날씨 변화에 따라 도로 표면은 건조, 습윤, 동결 등 다양한 상태로 변화하며, 이러한 변화는 도로를 주행하는 차량에 영향을 준다. 본 연구는 보편적으로 사용 중인 가시 카메라(Visible Camera)로 촬영한 도로 표면의 화상을 인식하여 도로 표면의 상태 정보를 생성할 수 있는 알고리즘을 개발하였다. 화상인식을 위한 입력 화상은 낮 시간대의 아스팔트 포장면에 대한 가시 카메라 화상을 촬영하여 도로 표면 상태의 화상을 확보하여, 편광계수 및 웨이블릿 변환(Wavelet transform)으로 도로 표면을 4가지의 상태(마른 땅, 젖은 땅, 동결, 적설)로 인식할 수 있는 알고리즘을 연구하였다. 표면 화상 인식 과정은 먼저, 편광계수(수직/수편 편광 비율) 값이 1.3 이상이면 젖은 땅으로 분류하고, 다음으로 젖은 땅을 제외한 나머지는 웨이블릿 패킷 변환을 통해 시간-주파수 분석을 수행하였다. 또한 영상 템플릿을 이용하여 마른 땅과 빙판의 표준적인 주파수 특성을 분석하여, 마른 땅과 빙판을 구분하였다. 이러한 과정을 검증하기 위해 실험을 통해 여러 패턴의 입력 영상에 대해서 제안한 알고리즘을 적용하여 양호한 성능을 보였으며, 결과적으로 영상 인식을 통해 도로 표면 상태를 감지할 수 있다는 결과를 얻었다. 앞으로 실용 및 제품화 연구를 통해 교통정보 뿐만아니라 도로 안전 서비스에도 활용 가능한 기술로 발전할 수 있을 것이다. Road surface conditions vary with changes of the weather as snow, rain, dust, shadow, So proper measures can be helpful in improving traffic conditions and safety. This research focus on developing algorithm that classifies road surfaces into four different categories, dry, wet, icy, and snowy surfaces by analyzing asphalt-paved road images taken in daylight. By using the polarization coefficients, the proportions of horizontally polarized components to vertically polarized components, regions with over 1.3 polarization coefficients are classified as wet surfaces. Except for wet surfaces, the algorithm applies time-frequency analysis to other parts by using the third order wavelet packet transform. in addition, by using the average frequency characteristics of dry and icy surfaces from image templates, decide which is closer to a test image, and finally identify dry and icy surfaces. It is confirmed that the proposed algorithm works well on various images. This can be interpreted as an indication that image-only road surface condition supervision is probable.