• Title/Summary/Keyword: 대칭함수

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A Study on the Anisotropy Inhomogeneity of Permalloy Thin Films (퍼말로이 박막의 이방성불균일에 관한 연구)

  • 장평우;최태원;유성초;김희중
    • Journal of the Korean Magnetics Society
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    • v.7 no.4
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    • pp.186-190
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    • 1997
  • We measured an anisotropy inhomogeniety and dispersion of rf sputterd permalloy thin films by TBP(Transverse Biased Permeability) measurement method. Angular distribution function had a shape similar to the Lorentzian distribution, but magnitude distribution function deviates from the sysmetric Lorentzian distribution because of long tail to the region of a high Hk value. With increasing film thickness, the angular and magnitude anisotropy dispersion increased. The increase of angular dispersion was due to both the increase of grain size and local anisotropy in thicker films.

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A Fuzzy Linear Programming Problem with Fuzzy Convergent Equality Constraints (퍼지 융합 등식 제약식을 갖는 퍼지 선형계획법 문제)

  • Oh, Se-Ho
    • Journal of the Korea Convergence Society
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    • v.6 no.5
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    • pp.227-232
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    • 2015
  • The fuzzy linear programming(FLP) is the useful approach to many real world problems under uncertainty. This paper deals with a FLP whose objective value is fuzzy. And the right hand sides of convergent equality constraints are fuzzy numbers. We assume that the membership function of the objective value is piecewise linear and those of the right hand side are trapezoidal. Each of these trapezoidal functions can be algebraically replaced with three linear functions. Then the FLP problem is transformed into the Zimmermann's symmetric model. The fuzzy solution based on the max-min rule can be obtained by solving the crisp linear programming problem derived from the symmetric model. A numerical example has illustrated our approach. The application of our approach to the inconsistent linear system can enable generate us to get define the useful and flexible inexact solutions within acceptable tolerance. Further research is required to generalize the membership function.

Cancellation of Motion Artifact in MRI (MRI에 있어서 체동 아티팩트의 제거)

  • 김응규
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.899-902
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    • 1998
  • 임상진단에 있어서 종종 문제가 되고 있는 호흡에 따른 두뇌부분의 가상적인 상하이동을 고려해서 위상 엔코드 축인 Y 방향만의 강체의 평행이동을 취급한다. 종래의 발견적인 축차 근사 반복처리에 의한 제거방법과는 달리, 본 연구에서는 MRI 촬상과정과 화상특성의 해석에 근거한 MRI 신호중의 체동성분과 화상성분을 단순한 대수연산에 의해 분리할 수 있는 새로운 구속조건을 도출한다. MRI 신호에 대해서 X 방향의 1차원 푸리에 변환을 행한 후의 Y 방향의 스펙트럼 위상값은 화상자신의 성분과 체동성분의 합이 되고 있다. 한편, 두뇌부위 등의 단층상에 있어서 주위의 피하지방 부분의 밀도는 거의 균일한 것 알려져 있어 이 부분위의 Y 방향의 1 라인 밀도분포를 대칭이라고 간주할 수 있다. 밀도함수가 대칭인 경우 스펙트럼의 위상은 그 위치에 대하여 선형적으로 변화한다. 따라서 이 선형함수로부터 벗어난 성분을 체동성분으로 분리할 수 있다. 이러한 구속조건에 기초를 둔 근거가 명확한 아티팩트의 제거방법을 제안한다. 아울러 본 방법의 유효성을 확인하기 위해 호흡에 의한 주기성의 체동을 가진 MRI 화상에 대해서 시뮬레이션을 행하였다.

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Viscoelastic stress analysis of nonaxisymmetrically heated cylindrical tubes (비축대칭 열하중을 받는 원통튜브의 점탄성 응력해석)

  • 박진석;서금석;김종인
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.396-403
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    • 1991
  • A solution is presented for the computation of the elastic-creep stresses in a hollow cylinder subjected to nonaxisymmetric temperature distribution. The creep problem is treated by the Maxwell creep model. Laplace transformation is used for reformation of the governing equation of elastic problem and Hooke's law in a function of .gamma. , .theta. , and creep constant. The governing equation is set up using the Airy stress function which leads to the biharmonic equation. The solution is obtained by using Fourer series method and Laplace inverse method used to obtain the stress components which include the variation of time. This solution shows excellent agreement with Lamkin's and Boley & Weiner's solution. The viscoelastic stresses are also obtained for the fuel rob tube subjecting nonaxisymmetric thermal load.

Estimation of 3-D Symmetric Shapes Using Shape-from-Shading Technique (Shape-from-Shading 기술을 이용한 대칭물체의 3차원 형상 예측)

  • Hong, Soon-Hwa;Hong, Dae-Hie
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.12
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    • pp.2503-2510
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    • 2002
  • Since the first shape-form-shading technique was developed by Horn in the early 1970s, many different approaches have been continuously emerging in the past three decades. Some of them improve existing techniques, while others are completely new approaches. Using the image reflectance equation, they estimate the 3-D shape of an object utilizing adequate constraints. Each algorithm applies different constraints such as brightness, smoothness, and integrability to solve the shape-from-shading problem. Especially for symmetric objects, a symmetry constraint is proposed to improve the performance of existing shape-from-shading algorithm in this paper. The symmetry constraint is imposed to a conventional algorithm and then the improvement in the performance of 3-D shape reconstruction is proved by quantitatively comparing the depth and gradient errors.

Cancellation of MRI Artifact due to Phase Encoding Axis Motion (위상 에코딩 방향의 체동에 의한 MRI 아티팩트의 제거)

  • 김응규
    • Proceedings of the Korean Information Science Society Conference
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    • 1998.10c
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    • pp.432-434
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    • 1998
  • 임상진단에 있어서 종종 문제가 되고 있는 호흡에 따른 두뇌부분의 가상적인 상하이동을 고려해서 위상 엔코드 축인 Y 방향만의 강체의 평행이동을 취급한다. 종래의 발견적인 축차 근사 반복처리에 의한 제거방법과는 달리, 본 연구에서는 MRI 촬상과정과 화성특성의 해석에 근거한 MRI 신호증의 체동성분과 화상성분을 단순한 대수연산에 의해 분리할 수 있는 새로운 구속조건을 도출한다. MRI 신호에 대해서 X방향의 1차원 푸리에 변환을 행한 후의 Y 방향의 스펙트럼 위상값은 화상자신의 성분과 체동성분의 합이 되고 있다. 한편, 두뇌부위 등의 단상층에 있어서 주위의 피하지방 부위의 밀도는 거의 균일한 것으로 알려져 있어 이 부분위의 Y 방향의 1 라인 밀도 분포를 대칭이라고 간주할 수 있다. 밀도함수가 대칭인 경우 스펙트럼의 위상은 그 위치에 대하여 선형적으로 변화하며 이 선형함수로부터 벗어난 성분을 체동성분으로 분리할 수 있다. 이러한 구속조건에 기초를 둔 근거가 명확한 아티팩트의 제거방법을 제안한다.

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Quantitative analysis of increase in depth of focus using Wigner distribution function (Wigner 분포 함수를 초점 심도 증가의 정량적 해석)

  • 장남영;강호정;은재정;최평석
    • Korean Journal of Optics and Photonics
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    • v.11 no.6
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    • pp.385-389
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    • 2000
  • A phase-retardation function which was derived from Wigner distribution function (WDF) is used to increase a focal depth of a radially symmetric optical system. The WDF for one-dimensional signal is represented as a two-dimensional function of phasespace ($\chi,\zeta$), and a normalized irradiance is described as a form of the Strehl ratio (SR). The increase in the focal depth is accomplished by delivering a shearing tilt a that represents a characteristic of free space propagation with simple manipulation in the WDF space. In this paper we propose a method for evaluating the focal depth quantitatively by representing the phaseretardation function in terms of the focal depth term. In order to verify the validity of the proposed method, we compared the numerically analyzed result with that of J. Sochki's study. study.

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Nonparametric estimation of conditional quantile with censored data (조건부 분위수의 중도절단을 고려한 비모수적 추정)

  • Kim, Eun-Young;Choi, Hyemi
    • Journal of the Korean Data and Information Science Society
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    • v.24 no.2
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    • pp.211-222
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    • 2013
  • We consider the problem of nonparametrically estimating the conditional quantile function from censored data and propose new estimators here. They are based on local logistic regression technique of Lee et al. (2006) and "double-kernel" technique of Yu and Jones (1998) respectively, which are modified versions under random censoring. We compare those with two existing estimators based on a local linear fits using the check function approach. The comparison is done by a simulation study.

Analysis of Spectral Response Specification for the Infrared Channels of Meteorological Imager (기상 영상기의 적외선 채널 분광 응답 규격에 대한 분석)

  • Cho, Young-Min
    • Aerospace Engineering and Technology
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    • v.6 no.2
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    • pp.104-110
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    • 2007
  • Analyzed is the spectral response profile specification used for the infrared (IR) channels of the meteorological imagers of GOES series geostationary satellites. The variation characteristics of effective wavelength and effective input radiance due to the change of the spectral response function profile within the imager performance specification are analyzed in order to propose how to understand the spectral response specification. As an analysis approach, at first a center symmetrical spectral response function and 4 worst case spectral response functions are selected within the spectral response specification, and then effective wavelength and effective input radiance are calculated for each spectral response function. As a result, the maximum allowable ranges of effective wavelength and effective input radiance are provided per the spectral response specification.

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Analysis of Subthreshold Swing for Doping Distribution Function of Asymmetric Double Gate MOSFET (도핑분포함수에 따른 비대칭 MOSFET의 문턱전압이하 스윙 분석)

  • Jung, Hakkee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.5
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    • pp.1143-1148
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    • 2014
  • This paper has analyzed the change of subthreshold swing for doping distribution function of asymmetric double gate(DG) MOSFET. The basic factors to determine the characteristics of DGMOSFET are dimensions of channel, i.e. channel length and channel thickness, and doping distribution function. The doping distributions are determined by ion implantation used for channel doping, and follow Gaussian distribution function. Gaussian function has been used as carrier distribution in solving the Poisson's equation. Since the Gaussian function is exactly not symmetric for top and bottome gates, the subthreshold swings are greatly changed for channel length and thickness, and the voltages of top and bottom gates for asymmetric double gate MOSFET. The deviation of subthreshold swings has been investigated for parameters of Gaussian distribution function such as projected range and standard projected deviation in this paper. As a result, we know the subthreshold swing is greatly changed for doping profiles and bias voltage.