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Centroaffine geometry of ruled surfaces and centered cyclic surfaces in $\mathbb R^4$
Yun Yang,Yanhua Yu 대한수학회 2018 대한수학회지 Vol.55 No.4
In this paper, we get several centroaffine invariant properties for a ruled surface in $\R^4$ with centroaffine theories of codimension two. Then by solving certain partial differential equations and studying a centroaffine surface with some centroaffine invariant properties in $\R^4$, we obtain such a surface is centroaffinely equivalent to a ruled surface or one of the flat centered cyclic surfaces. Furthermore, some centroaffine invariant properties for centered cyclic surfaces are considered.
NON-DEVELOPABLE RULED SURFACES WITH TIMELIKE RULING IN MINKOWSKI 3-SPACE
Yun Yang,Yanhua Yu 대한수학회 2015 대한수학회보 Vol.52 No.4
In this paper, using pseudo-spherical Frenet frame of pseudo-spherical curves in hyperbolic space, we define the notion of the structure functions on the non-developable ruled surfaces with timelike ruling. Then we obtain the properties of the structure functions and a complete classification of the non-developable ruled surfaces with timelike ruling in Minkowski 3-space by the theories of the structure functions.
B-spline Surface Blending by the Semi-structured B-spline
Hongwei Lin,Yunyang Xiong,Hongwei Liao (사)한국CDE학회 2013 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8
Surface blending is a useful operation in geometric design for rounding sharp edge or corner. Meanwhile, NURBS has already become the de facto industrial standard in existing CAD/CAM systems. Therefore, it is required to study how to blend two B-spline surfaces. However, two arbitrary B-spline surfaces (called base surfaces) are hard to be blended with a B-spline surface (called blending surface) because the knot vectors of the two base surfaces are usually mismatched. In this paper, we propose a curve-based spline representation, i.e., the semi-structured B-spline surface, which is generated by skinning a series of B-spline curves with different knot vectors. By assigning suitable knot vectors to the head and tail skinned curves, the semi-structured B-spline surface can blend two B-spline surfaces smoothly without disturbing them at all. We formulate the B-spline surface blending problem as an optimization problem with continuity constraints, and the continuity between the base and blending surfaces can reach G<SUP>2</SUP> or C<SUP>2</SUP>. Examples illustrated in this paper validate the effectiveness and efficiency of our method.
Adaptive reversible image watermarking algorithm based on DE
( Zhengwei Zhang ),( Lifa Wu ),( Yunyang Yan ),( Shaozhang Xiao ),( Shangbinggao ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.3
In order to improve the embedding rate of reversible watermarking algorithm for digital image and enhance the imperceptibility of the watermarked image, an adaptive reversible image watermarking algorithm based on DE is proposed. By analyzing the traditional DE algorithm and the generalized DE algorithm, an improved difference expansion algorithm is proposed. Through the analysis of image texture features, the improved algorithm is used for embedding and extracting the watermark. At the same time, in order to improve the embedding capacity and visual quality, the improved algorithm is optimized in this paper. Simulation results show that the proposed algorithm can not only achieve the blind extraction, but also significantly heighten the embedded capacity and non-perception. Moreover, compared with similar algorithms, it is easy to implement, and the quality of the watermarked images is high.
A Novel Flame Edge Detection Algorithm via a Novel Active Contour Model
Wanli Feng,Ying Li,Shangbing Gao,Yunyang Yan,Jianxun Xue 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.9
Flame edge detection from color images is a challenging research area recently. In this paper, an extension of active contour model is proposed by adding the two information types to both internal and external energy terms. Therefore, the combination of these two forces allows for flexible initialization of the contours. This energy is then incorporated into a level set formulation with a level set regularization term that is necessary for accurate computation in the corresponding level set method. Edge extraction of different flame images using C-V model and the classical edge detection operators are compared and analyzed. Experimental results show that the existing methods do not emphasize the continuity and clarity of the flame and fire edges while the proposed method identifies the continuous and clear edges of the flame fire.
An Improved Saliency Detection for Different Light Conditions
( Yongfeng Ren ),( Jingbo Zhou ),( Zhijian Wang ),( Yunyang Yan ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.3
In this paper, we propose a novel saliency detection framework based on illumination invariant features to improve the accuracy of the saliency detection under the different light conditions. The proposed algorithm is divided into three steps. First, we extract the illuminant invariant features to reduce the effect of the illumination based on the local sensitive histograms. Second, a preliminary saliency map is obtained in the CIE Lab color space. Last, we use the region growing method to fuse the illuminant invariant features and the preliminary saliency map into a new framework. In addition, we integrate the information of spatial distinctness since the saliency objects are usually compact. The experiments on the benchmark dataset show that the proposed saliency detection framework outperforms the state-of-the-art algorithms in terms of different illuminants in the images.
논문 키워드 네트워크 분석을 통한 군사과학기술 분야의 특징
김희수(Heesu Kim),김재현(Jaehyun Kim),최원석(Wonseok Choi),황인서(Inseo Hwang),김윤영(Yunyang Kim),임현재(Hyunjae Im),조영기(Youngki Cho) 육군사관학교 화랑대연구소 2021 한국군사학논집 Vol.77 No.1
Analysis of characteristic of the academic field is a important field of study handled by many fields, it allows to understand overall view of specific field by analyzing characteristic. The purpose of the study is to identify characteristic of Korean Military Science. First, we extracted 7528 keywords of 1842 published papers from 1998 to 2020 in the Journal of the Korean Military Science and Technology. Second, we build Keyword Network. Finally, using degree, nBetweetness and frequency of measurement Indicator of network, we analyzed the Keyword Network and examined its characteristics.