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A New Kmeans Clustering Algorithm for Point Cloud
Kun Zhang,Weihong Bi,Xiaoming Zhang,Xinghu Fu,Li Zhu,Kunpeng Zhou 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.9
With development of 3D scanner, it becomes more convenient to access point data. However, for processing the large-scale point cloud, it raised a new challenge for computer graphics. This paper places an emphasis on the point data own characteristics, and then the point data have been divided into certain point sets by clustering algorithm, that is will be divided into different clusters. In order to suit for the point data organization or space division, the clustering algorithm would be improved. This paper provided a new Kmeans algorithm with density constraints. Before processing the point cloud by Kmeans algorithm with density constraints, the density of the point cloud have been defined in this paper, the density of the point cloud can be used for quantification of the convergence. Finally, the Kmeans algorithm with density constraints is verified by the experiment results. Our experiment showed that the improved Kmeans can reduce the processing time, especially, As the increase of the value of K, that is number of cluster, the calculating time of the clustering algorithm can be decreased greatly. In addition, with the increases of the the scale of data size, the stability of the improved Kmeans algorithm has been verified.
Recent progress on polymer-based fluorescent and colorimetric chemosensors
Kim, Ha Na,Guo, Zhiqian,Zhu, Weihong,Yoon, Juyoung,Tian, He Royal Society of Chemistry 2011 Chemical Society reviews Vol.40 No.1
<P>Recently, fluorescent or colorimetric chemosensors based on polymers have attracted great attention due to several important advantages, such as their simplicity of use, signal amplification, easy fabrication into devices, and combination of different outputs, <I>etc</I>. This <I>tutorial review</I> will cover polymer-based optical chemosensors from 2007 to 2010.</P> <P>Graphic Abstract</P><P>This tutorial review covers polymer-based fluorescent and colorimetric chemosensors from 2007 to 2010. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0cs00058b'> </P>
Liu, Bo,Liu, Qingbin,You, Dan,Li, Xiaoyan,Naruta, Yoshinori,Zhu, Weihong The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.26
<P>The increasing electron-donating ability of the donor part is focused to further optimize the light-harvesting capability. Our strategy is to introduce an additional donor group into the indoline unit in the donor part to form a donor–donor structure (D–D moiety). Three different units (carbazole, fluorene and 4-methylphenyl groups) with different degrees of electron-donating capability are incorporated, thus constructing the specific donor–donor–π–acceptor (D–D–π–A) system (C-CA, F-CA and I-3) and giving a systematic view of the absorption evolution. Through molecular engineering, their light-harvesting capabilities, energy levels and photovoltaic performances were studied. As expected, utilizing strong electron-donating carbazole unit as additional donor, the IPCE spectrum of DSSC based on C-CA is successfully broadened to NIR region on the premise of suitable LUMO level, with an extraordinarily high plateau in visible region till around 700 nm. In the system of C-CA and F-CA, the introduction of <I>n</I>-pentyl group in donor part of carbazole and fluorene unit has little effect on preventing the molecular π-aggregation due to the good co-planarity of π-linker (vinyl thiophene), suggesting that the most effective way to prevent π-aggregation is still the incorporation of long alkyl groups into planar π-linker segment. However, the introducing long alkyl group can effectively prevent the electron recombination between electrons in conduction band (CB) of TiO<SUB>2</SUB> and I<SUB>3</SUB><SUP>−</SUP> ions. Along with the preferable light-harvesting capability, C-CA presents excellent IPCE performance with a short-circuit photocurrent (<I>J</I><SUB>sc</SUB>) of 18.53 mA cm<SUP>−2</SUP>, an open-circuit photovoltage (<I>V</I><SUB>oc</SUB>) of 649 mV, a fill factor of 0.71, corresponding to a power conversion efficiency (<I>η</I>) of 8.49%. The internal relations between chemical structure and conversion efficiency provide a strategy for developing highly efficient organic sensitizers working in whole visible region with high photovoltaic performance.</P> <P>Graphic Abstract</P><P>Utilizing a carbazole unit as additional donor, the photoresponse of C-CA is broadened to the NIR region with a <I>η</I> of 8.49%. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm31704d'> </P>
최유영 ( Choi Yu-young ),임철희 ( Lim Chul-hee ),류지은 ( Ryu J I-eun ),( Dongfan Piao ),강진영 ( Kang J In-young ),( Weihong Zhu ),( Guishan Cui ),이우균 ( Lee Woo-kyun ),전성우 ( Jeon Seong-woo ) 한국환경복원기술학회(구 한국환경복원녹화기술학회) 2017 한국환경복원기술학회지 Vol.20 No.3
This study constructed a high-resolution bioclimatic classification map of South Korea which classifies land into homogeneous zones by similar environment properties using advanced statistical techniques compared to existing ecological area classification studies. The climate data provided by WorldClim(1960-1990) were used to generate 27 bioclimatic variables affecting biological habitats, and key environmental variables were derived from Correlation Analysis and Principal Component Analysis. Clustering Analysis was performed using the ISODATA method to construct a 30`(~1km) resolution bioclimatic classification map. South Korea was divided into 21 regions and the results of classification were verified by correlation analysis with the Gross Primary Production(GPP), Actual Vegetation map made by the Ministry of Environment. Each zones` were described and named by its environmental characteristics and major vegetation distribution. This study could provide useful spatial frameworks to support ecosystem research, monitoring and policy decisions.
Cui, Guishan,Lee, Woo-Kyun,Kim, Damin,Lee, Eun Jung,Kwak, Hanbin,Choi, Hyun-Ah,Kwak, Doo-Ahn,Jeon, Seongwoo,Zhu, Weihong 한국식물학회 2014 Journal of Plant Biology Vol.57 No.4
This paper quantified carbon budget in the past 30 years (1981-2010) and identified the impact of land cover change on carbon dynamics using vegetation integrated simulator for trace gases (VISIT) model. North Korea was converted from carbon sink to source with $10.72{\pm}5.18TgCyr^{-1}$ of net ecosystem production (NEP) in the 1980s, $3.00{\pm}7.96TgCyr^{-1}$ in the 1990s, and $-0.46{\pm}5.13TgCyr^{-1}$ in the 2000s. NEP in South Korea was $10.55{\pm}1.09TgCyr^{-1}$ in the 1980s, $10.47{\pm}7.28TgCyr^{-1}$ in the 1990s, and $6.32{\pm}5.02TgCyr^{-1}$ in the 2000s, showing a gradual decline. In North Korea, NEP was decreased by $0.52Tgyr^{-1}$ in the 1990s due to reduction of forest, and increased by $0.36Tgyr^{-1}$ in the 2000s due to expansion of cropland. In South Korea, it was decreased by $0.24Tgyr^{-1}$ in the 1990s as urban and built-up area expanded, and increased by $0.04Tgyr^{-1}$ in the 2000s with the expansion of forest. These results suggest the importance of forest and land cover management against deforestation for ensuring national carbon balance.