• 대한수학회보
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• 제42권1호
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• pp.189-201
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• 2005

In this article, we establish relations between the sectional curvature function K and the shape operator, and also relationship between the k-Ricci curvature and the shape operator for slant submanifolds in generalized complex space forms with arbitrary codimension.

• Kyungpook Mathematical Journal
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• 제57권4호
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• pp.683-699
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• 2017

We introduce the notion of Killing shape operator for real hypersurfaces in the complex hyperbolic quadric $Q^{m*}=SO_{m,2}/SO_mSO_2$. The Killing shape operator implies that the unit normal vector field N becomes A-principal or A-isotropic. Then according to each case, we give a complete classification of real hypersurfaces in $Q^{m*}=SO_{m,2}/SO_mSO_2$ with Killing shape operator.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2009년도 추계학술발표대회 논문집
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• pp.104-108
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• 2009

Rapid urbanization resulted in expansion of urban area and increase of population bringing deepened housing shortage. Supply-oriented housing policy made apartment a representative residential space in Korea in spite of the short history of apartment. This study analyzed the shape and arrangement of main building by year and the microclimate in the complex depending on the number of floors. The purpose of this study was to present the basic data in developing apartment complex to solve problems like the stagnation of pollution source and the rise of temperature due to the declined ventilation in apartment complex, and the worsened urban heat island phenomenon due to the impeded flow of wind. This study rearranged the shape and arrangement of main building by year and the tendency of the number of floors by year in the process of change, by generalizing the process of change of apartment complex, a representative modern residential space through preliminary research. Based on it, 8 object lot by age was selected and simulated by using Envi-met. Simulation identified that the change of apartment complex takes place having a positive effect on microclimate in the apartment complex and the microclimate in the apartment complex is influenced a lot by the shape of complex. If in future apartment complex plan, a systematic legal criteria of design is made about the shape and arrangement of main building, it might have a positive effect on the improvement of microclimate in the apartment complex, a representative residential space in Korea.

• 대한수학회보
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• 제52권1호
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• pp.57-68
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• 2015

In this paper, we give a non-existence theorem of Hopf hypersurfaces in complex two-plane Grassmannians $G_2(\mathbb{C}^{m+2})$, $m{\geq}3$, whose shape operator is of Codazzi type in generalized Tanaka-Webster connection $\hat{\nabla}^{(k)}$.

• Journal of Plant Biology
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• 제34권3호
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• pp.229-238
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• 1991

The main objective of this study was to clarify the taxonomic status and the speciation mechanism of Viola albida complex in Korea. The complex includes three very closely related taxa, taxonomic ranks of which are much in dispute. These taxa in the complex are sympatric in distribution, and they are very similar in most morphological characteristics. Comparative morphological analyses revealed that they can be distinguished on the basis of leaf shape, although they show complicated patterns of variation in leaf shape. The variation of leaf shape in each taxon appeared to be maintained through developmental process, and extensive cleistogamy and vegetative reproduction in these taxa are suggested as the mechanisms maintaining the variation. Genetic variation in this complex was monomorphic in all 14 loci examined. Palynological study also showed that these taxa have the same pollen morphology. These results strongly suggested that they should be recognized as varieties of V. albida; var, albida, var. chaerophylloides, and var. takahashii. The results also suggested that some individuals that can be assigned to var. takahashii might be hybrids between var. albida and var. chaerophylloides.

• Kyungpook Mathematical Journal
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• 제57권3호
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• pp.525-535
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• 2017

In this paper, we consider two kinds of derivatives for the shape operator of a real hypersurface in a $K{\ddot{a}}hler$ manifold which are named the Lie derivative and the covariant derivative with respect to the k-th generalized Tanaka-Webster connection ${\hat{\nabla}}^{(k)}$. The purpose of this paper is to study Hopf hypersurfaces in complex Grassmannians of rank two, whose Lie derivative of the shape operator coincides with the covariant derivative of it with respect to ${\hat{\nabla}}^{(k)}$ either in direction of any vector field or in direction of Reeb vector field.

• 디지털융복합연구
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• 제15권4호
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• pp.267-273
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• 2017

각종 디지털 기기와 통신 기술의 발전으로 다양한 멀티미디어 콘텐츠의 생산과 유통이 폭발적으로 증가하고 있다. 이미지와 동영상 등의 멀티미디어 데이터의 검색을 위해서는 기존의 문자 위주의 검색과는 다른 접근 방식이 필요하다. 이미지의 여러 가지 물리적인 특징들을 정량화 하여 분석하고 이를 비교하여 유사한 이미지를 검색하는 내용기반 이미지 검색에서 색상과 모양은 주요 물리적 특징들이다. 지금까지는 색상과 모양을 서로 독립적인 특징으로 분리하여 이용하였지만, 인지적 관점에서 두 특징은 밀접한 관련이 있다. 본 논문에서는 색상과 모양 특징을 동시에 표현하기 위하여 3차원 색상 정보를 2차원 복소수 형식으로 표현하는 복소 색상 모델을 이용하여 색상의 공간적 분포 모양을 기술하는 방법을 제안한다. 복소 이미지를 주파수 변환한 후 저주파 영역의 소수의 계수만으로 복원하는 실험을 통하여 제안된 방법이 색상의 공간적 분포 모양을 효율적으로 표현할 수 있음을 보였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.575-578
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• 2005

Topographical images, in case of aerial or satellite images, are usually similar in colors and textures, and complex in shapes. Thus we have to use shape features of images for efficiently retrieving a query image from topographical image databases. In this paper, we propose a shape feature extraction method which is suitable for topographical images. This method, which improves the existing projection in the Cartesian coordinates, performs the projection operation in the polar coordinates. This method extracts three attributes, namely the number of region pixels, the boundary pixel length of the region from the centroid, the number of alternations between region and background, along each angular direction of the polar coordinates. It extracts the features of complex shape objects which may have holes and disconnected regions. An advantage of our method is that it is invariant to rotation/scale/translation of images. Finally we show the advantages of our method through experiments by comparing it with CSS which is one of the most successful methods in the area of shape feature extraction

• 대한수학회지
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• 제41권3호
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• pp.535-565
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• 2004

In this paper we consider the notion of ξ-invariant or (equation omitted)-invariant real hypersurfaces in a complex two-plane Grassmannian $G_2$( $C^{m+2}$) and prove that there do not exist such kinds of real hypersurfaces in $G_2$( $C^{m+2}$) with parallel second fundamental tensor on a distribution ζ defined by ζ = ξ U(equation omitted), where(equation omitted) = Span ｛ξ$_1$, ξ$_2$, ξ$_3$｝.X>｝.

• 대한수학회보
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• 제59권4호
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• pp.897-904
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• 2022

In this paper, we obtain an inequality involving the squared norm of the covariant differentiation of the shape operator for a real hypersurface in nonflat complex space forms. It is proved that the equality holds for non-Hopf case if and only if the hypersurface is ruled and the equality holds for Hopf case if and only if the hypersurface is of type (A).