• 제목/요약/키워드: symmetry

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Wavelet 변환을 이용한 정면 얼굴 검출에 관한 연구 (A Study on Frontal Face Detection Using Wavelet Transform)

  • 이상범;최영규
    • 인터넷정보학회논문지
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    • 제5권1호
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    • pp.59-66
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    • 2004
  • 대칭 영역 탐색은 대칭 정보를 이용하여 사전 정보 없이 얼굴영역을 추출 할 수 있다. 그러나 눈, 코, 입 등과 같은 얼굴의 특징 부위보다 탐색할 마스크의 크기가 커져야 함으로 이 방법은 계산 시간이 많이 걸린다. 본 논문에서는 얼굴 영상에 대하여 사전 정보 없이, 적은 계산량으로 얼굴 영역 추출이 가능하도록 대칭 영역 탐색 및 웨이블릿 변환을 이용하여 얼굴 영역의 추출과 그 특징에서의 대칭간에 따른 영상을 이용하여 원영상에서는 영역 분할을 통한 얼굴 영역 추출 방법을 제안하고 실험을 통하여 이를 확인하였다.

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초등기하에서 도형의 대칭에 관한 연구 (On symmetry of figures in elementary geometry)

  • 한길준;신봉숙
    • 한국수학사학회지
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    • 제20권2호
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    • pp.73-88
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    • 2007
  • 대칭은 수학뿐만 아니라 생활에서 널리 이용되는 개념으로 5-나 단계에서 도형의 대칭을 다루고 있다. 본 연구는 도형의 대칭 지도를 위해 대칭과 대칭지도에 관한 역사적 배경, 수학적 배경, 교육과정에서의 위계를 살펴보고, 아동에게 대칭에서 발생하는 주요 오류와 그 원인을 규명하여 이를 극복하기 위한 아이디어를 얻고자 한다.

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Dynamic Responses in Orthotropic Media Due to Pulsating Line Source

  • Kim, Yong-Yun
    • The Journal of the Acoustical Society of Korea
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    • 제17권1E호
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    • pp.70-75
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    • 1998
  • The analysis of dynamic responses are carried out on several anisotropic systems due to buried pulsating line sources. These include infinite, semi-infinite spaces. The media possess orthotropic or higher symmetry. The load is in the from of a normal stress acting with parallel to symmetry axis on the plane of symmetry within the materials. The results are first derived for infinite media. Subsequently the results for semi-infinite are derived by using superposition of the solution in the infinite medium together with a scattered solution from the boundaries. The sum of both solutions has to satisfy stress free boundary conditions, thereby leading to the complete solutions. The solutions are simplified to the systems possessing of higher symmetry, such as orthotropic, transversely isotropic, cubic, and isotropic symmetry.

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Neutrino Oscillation and S4 Flavor Symmetry

  • Park, Jong-Chul
    • Applied Science and Convergence Technology
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    • 제27권5호
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    • pp.86-89
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    • 2018
  • Observations of neutrino oscillations are very strong evidence for the existence of neutrino masses and mixing. From recent experimental results on neutrino oscillation, we find that neutrino mixing angles are quite consistent with the so-called tri-bi-maximal mixing pattern, but the deviation from observational results is non-negligible. However, the tri-bi-maximal mixing pattern is still useful as a leading order approximation and provides a good guideline to search for the flavor symmetry in the neutrino sector. We introduce the $S_4$ permutation symmetry as a flavor symmetry to the standard model of particle physics with additional particle contents of heavy right-handed neutrinos and scalar fields. Finally, we obtain the tri-bi-maximal mixing pattern as a mixing matrix in the lepton sector within the suggested model. To derive the required unitary mixing matrix for the neutrino sector, the double seesaw mechanism is utilized.

Optical Triangular Waveform Generation with Alterable Symmetry Index Based on a Cascaded SD-MZM and Polarization Beam Splitter-combiner Architecture

  • Dun Sheng Shang;Guang Fu Bai;Jian Tang;Yan Ling Tang;Guang Xin Wang;Nian Xie
    • Current Optics and Photonics
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    • 제7권5호
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    • pp.574-581
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    • 2023
  • A scheme is proposed to generate triangular waveforms with alterable symmetry. The key component is a cascaded single-drive Mach-Zehnder modulator (SD-MZM) and optical polarization beam splitter-combiner architecture. In this triangular waveform generator, the bias-induced phase shift, modulation index and controllable delay difference are changeable. To generate triangular waveform signals with different symmetry indexes, different combinations of these variables are selected. Compared with the previous schemes, this generator just contains one SD-MZM and the balanced photodetector (BPD) is not needed, which means the costs and energy consumption are significantly reduced. The operation principle of this triangular waveform generator has been theoretically analyzed, and the corresponding simulation is conducted. Based on the theoretical and simulated results, some experiments are demonstrated to prove the validity of the scheme. The triangular waveform signals with a symmetry factor range of 20-80% are generated. Both experiment and theory prove the feasibility of this method.

Elastic Wave Propagation in Monoclinic System Due to Harmonic Line Load

  • Kim, Yong-Yun
    • The Journal of the Acoustical Society of Korea
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    • 제17권2E호
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    • pp.47-52
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    • 1998
  • An analysis of dynamic responses is carried out on monoclinic anisotropic system due to a buried harmonic line source. The load is in the form of a normal stress acting along an arbitrary axis on the plane of symmetry within the orthotropic materials: In case that the line load is acting along the symmetry axis normal to the plane of symmetry, plane wave equation is coupled with verital shear wave and longitudinal wave. However, if the line load is acting along an arbitrary axis normal to the plane of symmetry, plane wave equation is coupled with vertical shear wave, longitudinal wave and horizontal shear wave. We first considered the equation of motion in a reference coordinate system, where the line load is coincident with a symmetry axis of the orthotropic material. Then the equation of motion is transformed into one with respect to general coordinate system with azimuthal angle by using transformation tensor. Plane wave solutions of monoclinic systems are derived for infinite media. Finally complete solutions for the plane harmonic wave are obtained by calculating the inverse of the integral transforms, in which bulk wave poles are avoided by deforming the contour of the integration to the complex plane. Numerical results for examples of orthotropic material belonging to monoclinic symmetry are demonstrated.

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CAD for Detection of Brain Tumor Using the Symmetry Contribution From MR Image Applying Unsharp Mask Filter

  • Kim, Dong-Hyun;Ye, Soo-Young
    • Transactions on Electrical and Electronic Materials
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    • 제15권4호
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    • pp.230-234
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    • 2014
  • Automatic detection of disease helps medical institutions that are introducing digital images to read images rapidly and accurately, and is thus applicable to lesion diagnosis and treatment. The aim of this study was to apply a symmetry contribution algorithm to unsharp mask filter-applied MR images and propose an analysis technique to automatically recognize brain tumor and edema. We extracted the skull region and drawed outline of the skull in database of images obtained at P University Hospital and detected an axis of symmetry with cerebral characteristics. A symmetry contribution algorithm was then applied to the images around the axis of symmetry to observe intensity changes in pixels and detect disease areas. When we did not use the unsharp mask filter, a brain tumor was detected in 60 of a total of 95 MR images. The disease detection rate for the brain was 63.16%. However, when we used the unsharp mask filter, the tumor was detected in 87 of a total of 95 MR images, with a disease detection rate of 91.58%. When the unsharp mask filter was used in the pre-process stage, the disease detection rate for the brain was higher than when it was not used. We confirmed that unsharp mask filter can be used to rapidly and accurately to read many MR images stored in a database.

Site-Directed Mutation Effect of the Symmetry Region at the mRNA 5'-end of Escherichia coli aeg-46.5 Gene

  • Ahn, Ju-Hyuk;Choe, Mu-Hyeon
    • BMB Reports
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    • 제29권1호
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    • pp.92-97
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    • 1996
  • The age-46.5 gene of Escherichia coli is induced by nitrate ion and regulated by Fnr, NarL, and NarP during anaerobic growth. aeg-46.5::lacZ fusion gene shows its maximum expression in narL host after two hours of aerobic to anaerobic switch in M9-Glc-nitrate medium. Fnr and NarP act as positive regulators, and NarL acts as a negative regulator. The control region of the aeg-46.5 was identified and the binding sites of regulator proteins have been predicted (Reznikoff and Choe (1993)). It has two symmetry regions. One is located at -52~-37 bp from the anaerobic mRNA 5'-end, which is the binding site of NarL and NarP. The other is located at +37~+56 bp from the 5'-end of mRNA. In this study, the downstream symmetry region from the mRNA 5'-end was investigated by site-directed mutagenesis. The destruction of the symmetry region increases the expression level of aeg-46.5. We propose that the symmetry region interferes with the expression of aeg-46.5 possibly by forming a stem-and-loop structure.

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직교스프링들에 의해 지지되는 강체의 진동 설계 (Vibration Design of a Rigid Body Supported by Orthogonal Springs)

  • 장선준;이준호;최용제
    • 대한기계학회논문집A
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    • 제31권1호
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    • pp.97-104
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    • 2007
  • Vibration analysis of a rigid body supported by in-parallel linear springs can be greatly simplified by utilizing the conditions for a plane of symmetry. The vibration modes of an oscillatory system having plane of symmetry are classified into the in-plane and out-of-plane modes. From the viewpoint of screw theory, they represent respectively the vibration axes perpendicular to the plane of symmetry and lying in the plane of symmetry. In this paper, the sets of orthogonal and mutually intersecting three springs are used as resilient support of a rigid body. The geometrical conditions for the system to have a plane of symmetry and diagonalized stiffness matrix are presented. From the orthogonality of the vibration modes with respect to the inertia matrix, the geometrical relation between the reaction wrenches and the vibration modes are derived. This geometrical relation is then used to get the cubic design equation for the design of out-of-plane modes. The numerical design example of engine mounts is presented in order to explain the suggested design technique.

An Acceleration Method for Symmetry Detection using Edge Segmentation

  • Won, Bo Whan;Koo, Ja Young
    • 한국컴퓨터정보학회논문지
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    • 제20권9호
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    • pp.31-37
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    • 2015
  • Symmetry is easily found in animals and plants as well as in artificial structures. It is useful not only for human cognitive process but also for image understanding by computer. Application areas include face detection and recognition, indexing of image database, image segmentation and detection, and analysis of medical images. The method used in this paper extracts edges, and the perpendicular bisector of any pair of selected edge points is considered to be a candidate axis of symmetry. The coefficients of the perpendicular bisectors are accumulated in the coefficient space. Axis of symmetry is determined to be the line for which the histogram has maximum value. This method shows good results, but the usefulness of the method is restricted because the amount of computation increases proportional to the square of the number of edges. In this paper, an acceleration method is proposed which performs $2^{2n}$ times faster than the original one. Experiment on 20 test images shows that the proposed method using level-3 image segmentation performs 63.9 times faster than the original method.