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Reduced structural anisotropy of (1122) semipolarGaN by using epitaxial lateral overgrowth
조한수,황종희,전대우,주진우 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.9
NonpolarGaN and semipolarGaN have been studied for minimization of quantum confined Stark effect in c-plane GaN. A(1122) semipolarGaN layer was grown on m-plane sapphire substrates via epitaxial lateral overgrowth (ELOG) by metalorganic chemical vapor deposition. Cross section filed emission scanning electron microscopy revealed a semipolarGaN layerwith a smooth surface and an inverted trapezoid growth shape. For the layers not fully merged laterally, the structuralanisotropic characteristics were reduced slightly. After merging laterally, the structural anisotropy was reduced significantly. In the [1100] directions of the X-ray beams, the full width at half maximum (FWHM)of the x-ray rocking curve of the (1122)plane was 1195 arcsec for semipolarGaN on unpatterned template and the FWHM decreased to 468 arcsec for mergedsemipolarGaN by ELOG.In addition, the optical properties of (1122) semipolarGaN using ELOG were improved significantly.
빈도수를 고려한 눈동자색 분포맵에 기반한 조명 변화에 강건한 얼굴 검출 방법
조한수 한국인터넷방송통신학회 2009 한국인터넷방송통신학회 논문지 Vol.9 No.5
본 논문에서는 빈도수를 고려한 눈동자색 분포맵에 기반한 조명변화에 강건한 얼굴 검출 방법을 제안한다. 제안한 방법은 먼저, 피부색 분포맵을 이용하여 검출된 얼굴 후보영역에서 색상성분의 편차를 이용하여 얼굴 후보영역을 축소한다. 이 영역에서 눈 후보점을 탐색하기 위해 눈동자색 분포맵을 적용하여 눈 후보영역을 검출한다. 검출된 눈 후보영역은 조명 보정 기법과 분할 알고리즘에 따라 눈 후보영역을 반복적으로 분할함으로써 조명의 영향으로 얼굴 영역이 아주 어두운 경우에도 눈 검출 성능을 향상할 수 있다. 분할된 눈 후보영역에서 템플릿 정합방법으로 눈 후보점을 검출하고 두 눈 후보점 쌍과 입 평가치를 이용하여 얼굴을 검출하였다. 실험결과 제안된 방법은 좋은 성능을 보였다.
조한수,강길선,홍민성,심정보,Randall F. Ankeny,김형석,Robert M. Nerem 한국고분자학회 2015 Macromolecular Research Vol.23 No.11
Poly(lactic-co-glycolic acid) (PLGA) is a copolymer used for scaffolds in tissue engineering due to its biodegradable and biocompatible properties. Demineralized bone particle (DBP) is a natural material containing bone morphogenic proteins (BMPs). The objective of this study was to determine if DBP induced differentiation of mesenchymal stem cells (MSCs) into a smooth muscle cells (SMCs) phenotype and act in a similar manner when treated with TGF-β1 as SMCs under the same conditions. PLGA scaffolds were fabricated with or without DBP using the solvent casting/salt leaching technique. Proliferation of MSCs and SMCs was measured using the MTT assay, while the expression of the smooth muscle-specific markers α-smooth muscle actin (α-SMA), smooth muscle 22 alpha (SM22α), and calponin was measured using RT-PCR and western blotting. Results showed PLGA with DBP scaffolds increased cell proliferation of SMCs (1 and 3 days) and MSCs (3 and 7 days) compared to the PLGA only scaffolds. Smooth muscle-specific genes were significantly increased in SMCs cultured for 7 days on PLGA with DBP scaffolds compared to PLGA only scaffolds and were also significantly increased when used SMC medium containing TGF-β1. Interestingly, the smooth muscle-specific genes were not altered in MSCs by the addition of TGF-β1 to the PLGA with DBP. However, in the 6-well and PLGA only groups, TGF-β1 addition caused increased levels of SM22α and calponin mRNA. Western blotting results were similar to the mRNA levels. These results suggest that the cell growth and gene expression of SMCs were up-regulated by DBP and TGF-β1 in PLGA scaffold; however, they were inadequate for the shift of MSCs into a SMCs phenotype.