• Title/Summary/Keyword: Geometrical Characteristics

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Formulation of a Singular Finite Element and Its Application (특이 유한요소의 구성과 응용)

  • Kim, Myung-Sik;Lim, Jang-Keun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.6 s.165
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    • pp.1018-1025
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    • 1999
  • For the effective analysis of two dimensional plane problems with geometrical discontinuities, singular finite element has been proposed. The element matrix equation was formulated on the basis of hybrid variational principle and Trefftz function sets derived consistently from the complex theory of plane elasticity by introducing a conformal mapping function. In order to suggest the accuracy characteristics of the proposed singular finite element, typical plane problems were analyzed and these results were compared with exact solutions. The singular finite element gives the comparatively exact values of stress concentration factors or stress intensity factors and can be effectively used for the analysis of mechanical structures containing various geometrical discontinuities.

Spectral line Variations of the Symbiotic Variable CH Cygni

  • Yoo Kye Hwa;Kim Kang Min;Lee Byung Chul;Yoon Tae Seog;Lee Jung Ae;Kang Yong Hee
    • Journal of the Korean earth science society
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    • v.26 no.2
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    • pp.160-165
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    • 2005
  • A series of high resolution spectra of CH Cygni obtained at the Bohyunsan Optical Astronomy Observatory (BOAO) in April 2004 has been analyzed. The emission components of the [O I] 6300 A lines are de-convoluted and fitted with Gaussian functions in order to investigate the characteristics and the structure of CH Cygni system along with the analysis for Hα and [O III] lines. A present geometrical structure of the components of CH Cygni system is suggested.

A New Method of Finding Real Roots of Nonlinear System Using Extended Fixed Point Iterations (확장된 고정점이론을 이용한 비선형시스템의 근을 구하는 방법)

  • Kim, Sung-Soo;Kim, Ji-Soo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.2
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    • pp.277-284
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    • 2018
  • In this paper, a new numerical method of finding the roots of a nonlinear system is proposed, which extends the conventional fixed point iterative method by relaxing the constraints on it. The proposed method determines the real valued roots and expands the convergence region by relaxing the constraints on the conventional fixed point iterative method, which transforms the diverging root searching iterations into the converging iterations by employing the metric induced by the geometrical characteristics of a polynomial. A metric is set to measure the distance between a point of a real-valued function and its corresponding image point of its inverse function. The proposed scheme provides the convenience in finding not only the real roots of polynomials but also the roots of the nonlinear systems in the various application areas of science and engineering.

A Geometrical Analysis Method of ELC Lens for The 3D Display for Optimum Design (3차원 영상출력을 위한 ELC 렌즈의 기하광학적 해석 방법 및 최적 설계)

  • Kim, Bong-Sik;Kim, Keon-Woo;Baik, Seung-Jo;Park, Woo-Sang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.6
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    • pp.457-461
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    • 2013
  • In this paper, a novel method based on geometrical optics is proposed to calculate the optical characteristics of an electric field driven liquid crystal (ELC) lens. For an optimally designed ELC lens, effective refractive index is calculated and then ray tracing is carried out using Huygens' principle. From the results, the intensity distribution at the optimum viewing distance (OVD) is obtained. To confirm the validity of our work, the result is compared with that calculated by the extended Jones matrix method (EJMM). As a result, it turns out that the novel method provides more simple and rigorous simulation results than the EJMM.

Pressure Distribution Simulation on Geometrical Manifolds Structure for Fabrication of a Planar-type Fuel-Cell Stack (평판형 연료전지 스택의 제조를 위한 매니폴드 형상별 압력분포 시뮬레이션)

  • Park, Se-Joon;Choi, Young-Sung;Lee, Kyung-Sup
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.58 no.4
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    • pp.609-614
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    • 2009
  • A fuel-cell power system among various alternative power sources has many advantages such as comparatively independable circumstances, high-efficient, and heat-recyclable, thus it is now able to be up to hundreds MWh-scaled through improving feasibility and longevity of it. During the last few decades, numerous research results has been investigated to expand interest in fuel-cell technology. This study presents pressure distribution on the geometrical manifold structures, which are U-type and Z-type, of a planar-type fuel-cell stack by simulated with computational fluid dynamics(CFD). Then, electrical performance of a 200W fuel-cell stack, which is U-type, was diagnosed after pre-conditioning operation. The stack has electrical characteristics ; 22V, 10A, 220W, and current density 200mA/cm2.

A Note on the Hull Form Variational Methods (선형변환 방법에 대한 소고)

  • 이춘주;윤현세;유재문
    • Journal of the Society of Naval Architects of Korea
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    • v.40 no.1
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    • pp.63-68
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    • 2003
  • Systematic geometrical variation method of hull forms, such as "1 -Cp", "Swinging" and "Lackenby" are widely used in the early stage of a new design from those of a similar parent ship, which shows a better performance through the model test and/or sea trials. This method is simple and easy to modify original hull forms without changing the main characteristics. The shape of the prismatic curie can be easily varied by these methods, however, the frame line shape in the body plan can′t be generated easily, when the section shapes are complicated or have discontinuities or the mismatch of the body plan and the stem and stern profiles. To overcome this drawback of the hull form variations, a simple and useful method has been proposed in the present study.

Attenuation of S wave of the Southeastern Part of the Korean Peninsula (한반도 동남부의 S파 감쇠)

  • 박동희
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2001.04a
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    • pp.51-57
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    • 2001
  • In order to estimate attenuation characteristics, nonparametric model is used. Evaluation of this model requires suites of average spectral amplitude data as a function of distance without adopting any assumed parametric forms. Values of Quality factor, Q were estimated for individual frequencies by matrix inversion of S wave amplitude spectra for 21 records of 8 small and intermediate earthquakes (2.7(1/r)1/2. The best models for 1/Q values were found to be 0.000453+0.001851/f and 0.000451+0.009261/f, respectively. This results can be compared to the conventional functional form of Q=afb and be used to estimate source spectra and site response.

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Optimum Geometric and Electrical Parameter for Minimization Torque Ripple of Switched Reluctance Motor (스위치드 릴럭턴스 전동기의 토오크 리플 저감을 위한 기하학적인 파라미터와 전기적인 파라미터의 최적화)

  • Choi, Jae-Hak;Kim, Sol;Lee, Kab-Jae;Lee, Ju;Hong, Kyung-Jin;Choi, Dong-Hoon
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.3
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    • pp.93-100
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    • 2003
  • Switched reluctance motor(SRM) has some advantages such as low cost, high torque density but SRM has essentially high torque ripple due to its salient structure. In order to apply SRM to industrial field, torque ripple has to be reduced. This paper introduces optimal design process of SRM using an optimization algorithm of Progressive Quadratic Response Surface Modeling(PQRSM) and two-dimensional(2D) Finite Element Method(FEM). The electrical and geometrical design parameters have been adopted as 2D design variables. From this work, it can be obtained both the optimal design minimized torque ripple and the optima1 design maximized the average torque, respectively. Finally, this Paper Presents Performance comparison of two optimal designs and consider influence of the selected design variables in torque characteristics.

Automatic Face Identification System Using Adaptive Face Region Detection and Facial Feature Vector Classification

  • Kim, Jung-Hoon;Do, Kyeong-Hoon;Lee, Eung-Joo
    • Proceedings of the IEEK Conference
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    • 2002.07b
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    • pp.1252-1255
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    • 2002
  • In this paper, face recognition algorithm, by using skin color information of HSI color coordinate collected from face images, elliptical mask, fratures of face including eyes, nose and mouth, and geometrical feature vectors of face and facial angles, is proposed. The proposed algorithm improved face region extraction efficacy by using HSI information relatively similar to human's visual system along with color tone information about skin colors of face, elliptical mask and intensity information. Moreover, it improved face recognition efficacy with using feature information of eyes, nose and mouth, and Θ1(ACRED), Θ2(AMRED) and Θ 3(ANRED), which are geometrical face angles of face. In the proposed algorithm, it enables exact face reading by using color tone information, elliptical mask, brightness information and structural characteristic angle together, not like using only brightness information in existing algorithm. Moreover, it uses structural related value of characteristics and certain vectors together for the recognition method.

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A Study on Feed Rate Optimization in the Ball End-milling Process Regarding of Tool Path and Workpiece Shape (볼 엔드밀을 이용한 금형가공에 있어서 이송 속도 최적화에 대한 연구)

  • 김성윤
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.04a
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    • pp.102-106
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    • 1996
  • In the ball end-milling process of a 3-dimensional mold, it is important to select cutting conditions and tool path considering the geometrical shape of a workpiece to reduce machining time. In this study, experiments were performed to decide allowable feed rate not breaking stability of system for different geometrical shapes. It was found that downcut is more stable than upcutting in machining side wall and downward is preferable to upward in inclined part depending on the angle of the inclination and depth of cut.

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