• 제목/요약/키워드: 가우스법

Search Result 119, Processing Time 0.022 seconds

Time Domain Seismic Waveform Inversion based on Gauss Newton method (시간영역에서 가우스뉴튼법을 이용한 탄성파 파형역산)

  • Sheen, Dong-Hoon;Baag, Chang-Eob
    • 한국지구물리탐사학회:학술대회논문집
    • /
    • 2006.06a
    • /
    • pp.131-135
    • /
    • 2006
  • A seismic waveform inversion for prestack seismic data based on the Gauss-Newton method is presented. The Gauss-Newton method for seismic waveform inversion was proposed in the 80s but has rarely been studied. Extensive computational and memory requirements have been principal difficulties. To overcome this, we used different sizes of grids in the inversion stage from those of grids in the wave propagation simulation, temporal windowing of the simulation and approximation of virtual sources for calculating partial derivatives, and implemented this algorithm on parallel supercomputers. We show that the Gauss-Newton method has high resolving power and convergence rate, and demonstrate potential applications to real seismic data.

  • PDF

Effective Parameter Estimation of Bernoulli-Gaussian Mixture Model and its Application to Image Denoising (베르누이-가우스 혼합 모델의 효과적인 파라메터 추정과 영상 잡음 제거에 응용)

  • Eom, Il-Kyu;Kim, Yoo-Shin
    • Journal of the Institute of Electronics Engineers of Korea SP
    • /
    • v.42 no.5 s.305
    • /
    • pp.47-54
    • /
    • 2005
  • In general, wavelet coefficients are composed of a few large coefficients and a lot of small coefficients. In this paper, we propose image denoising algorithm using Bernoulli-Gaussian mixture model based on sparse characteristic of wavelet coefficient. The Bernoulli-Gaussian mixture is composed of the multiplication of Bernoulli random variable and Gaussian mixture random variable. The image denoising is performed by using Bayesian estimation. We present an effective denoising method through simplified parameter estimation for Bernoulli random variable using local expected squared error. Simulation results show our method outperforms the states-of-art denoising methods when using orthogonal wavelets.

Numerical Calculation Method for Paraxial Zoom Loci of Complicated Zoom Lenses with Infinite Object Distance by Using Gaussian Bracket Method (가우스 괄호법을 이용한 무한 물점을 갖는 복잡한 줌 렌즈의 수치해석적인 근축광선 줌 궤적 추적법)

  • Yoo, Nam-Jun;Kim, Won-Seob;Jo, Jae-Heung;Ryu, Jae-Myung;Lee, Hae-Jin;Kang, Geon-Mo
    • Korean Journal of Optics and Photonics
    • /
    • v.18 no.6
    • /
    • pp.410-420
    • /
    • 2007
  • We theoretically derive the set of utilizable paraxial zoom locus equations for all complicated zoom lens systems with infinite object distance, such as a camera zoom lens, by using the Gaussian bracket method and the matrix representation of paraxial ray tracing. And we make the zoom locus program according to these equations in Visual Basic. Since we have applied the paraxial ray tracing equations into Gaussian bracket representation, the resultant program systematically simplifies various constraints of the zoom loci of various N group types. Consequently, the solutions of this method can be consistently used in all types of zoom lens in the step of initial design about zoom loci. Finally, in order to verify the usefulness of this method, we show that one example among 4 groups and that among 5 groups, which are very complex zoom lens systems, can be rapidly and with versatility traced through various interpolations by using this program.

Sensitivity Analysis of Ordinary Kriging Interpolation According to Different Variogram Models (베리오그램 모델 변화에 따른 정규 크리깅 보간법의 민감도분석)

  • Woo, Kwang-Sung;Park, Jin-Hwan;Lee, Hui-Jeong
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.21 no.3
    • /
    • pp.295-304
    • /
    • 2008
  • This paper comprises two specific objectives. The first is to examine the applicability of Ordinary Kriging interpolation(OK) to finite element method that is based on variogram modeling in conjunction with different allowable limits of separation distance. The second is to investigate the accuracy according to theoretical variograms such as polynomial, Gauss, and spherical models. For this purpose, the weighted least square method is applied to obtain the estimated new stress field from the stress data at the Gauss points. The weight factor is determined by experimental and theoretical variograms for interpolation of stress data apart from the conventional interpolation methods that use an equal weight factor. The validity of the proposed approach has been tested by analyzing two numerical examples. It is noted that the numerical results by Gauss model using 25% allowable limit of separation distance show an excellent agreement with theoretical solutions in literature.

Gaussian Kernel Smoothing of Explicit Transient Responses for Drop-Impact Analysis (낙하 충격 해석을 위한 명시법 과도응답의 가우스커널 평활화 기법)

  • Park, Moon-Shik;Kang, Bong-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.35 no.3
    • /
    • pp.289-297
    • /
    • 2011
  • The explicit finite element method is an essential tool for solving large problems with severe nonlinear characteristics, but its results can be difficult to interpret. In particular, it can be impossible to evaluate its acceleration responses because of severe discontinuity, extreme noise or aliasing. We suggest a new post-processing method for transient responses and their response spectra. We propose smoothing methods using a Gaussian kernel without in depth knowledge of the complex frequency characteristics; such methods are successfully used in the filtering of digital signals. This smoothing can be done by measuring the velocity results and monitoring the response spectra. Gaussian kernel smoothing gives a better smoothness and representation of the peak values than other approaches do. The floor response spectra can be derived using smoothed accelerations for the design.

Characteristics of Everett Function Formulated with Gaussian Distribution (가우스 분포에 의해 정식화된 에버렐 함수의 특성)

  • Hong, Sun-Ki;Kim, Hong-Kyu;Lee, Chang-Hwan;Jung, Hyun-Kyo
    • Proceedings of the KIEE Conference
    • /
    • 1997.07a
    • /
    • pp.15-17
    • /
    • 1997
  • 에버�� 함수는 상호자계 축을 따라 가우스 분포를 가지므로 정식화될 수 있다. 본 연구에서는 에버렐 함수의 정식화 원리를 설명하고, 오차를 최소화하기 위해 최소 자승법을 도입한다. 이로부터 얻은 에버렐 함수로부터 히스테리시스 루프를 시뮬레이션하고, 이를 통해 제안된 방법의 타당성을 확인한다.

  • PDF

A Study on Gauss Conformal Double and Gauss-Kruger's Map Projection (가우스 이중투영과 가우스크뤼게 투영법에 대한 연구)

  • 전재홍;조규전
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
    • /
    • v.16 no.2
    • /
    • pp.337-343
    • /
    • 1998
  • In Korea, map coordinates has been confused in use since the map projection system has been complicated by using two different methods i.e., Gauss conformal double projection and Gauss-Kruger projection which are com-plicated in using through history. So, we have to understand the two projections' characteristics and differences. In this study, we would find out a fact that the maximum difference occurred in longitude and latitude is about 15cm at the Korean peninsular. This shift is accepted as proper in GIS and cartographic application but should be considered carefully in converting of the geodetic control point coordinates.

  • PDF

Image Denoising Using Bivariate Gaussian Model In Wavelet Domain (웨이블릿 영역에서 이변수 가우스 모델을 이용한 영상 잡음 제거)

  • Eom, Il-Kyu
    • Journal of the Institute of Electronics Engineers of Korea SP
    • /
    • v.45 no.6
    • /
    • pp.57-63
    • /
    • 2008
  • In this paper, we present an efficient noise reduction method using bivariate Gaussian density function in the wavelet domain. In our method, the probability model for the interstate dependency in the wavelet domain is modeled by bivariate Gaussian function, and then, the noise reduction is performed by Bayesian estimation. The statistical parameter for Bayesian estimation can be approximately obtained by the $H{\ddot{o}}lder$ inequality. The simulation results show that our method outperforms the previous methods using bivariate probability models.

Performance of DS/SSMA communication systems over frequency selective rician fading channels with gaussian and impulsive noise (가우스 잡음과 임펄스 잡음이 혼합된 주파수 선택적 리시안 페이딩 채널에서 DS/SSMA 통신시스템의 성능분석)

  • 진익수;안재영;이동도;황금찬
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.21 no.2
    • /
    • pp.461-470
    • /
    • 1996
  • In this paper, the average probability of bit error of direct sequence spread spectrum multiple access (DS/SSMA) communication system is derived over frequency-selective rician fading channels with Gaussian and impulsive noise. Multiple access interference due to K asynchronous users transmitting simultaneously is computed using the characteristic function method, and compared with Gaussian approximation.

  • PDF

Maximum likelihood estimation of Logistic random effects model (로지스틱 임의선형 혼합모형의 최대우도 추정법)

  • Kim, Minah;Kyung, Minjung
    • The Korean Journal of Applied Statistics
    • /
    • v.30 no.6
    • /
    • pp.957-981
    • /
    • 2017
  • A generalized linear mixed model is an extension of a generalized linear model that allows random effect as well as provides flexibility in developing a suitable model when observations are correlated or when there are other underlying phenomena that contribute to resulting variability. We describe maximum likelihood estimation methods for logistic regression models that include random effects - the Laplace approximation, Gauss-Hermite quadrature, adaptive Gauss-Hermite quadrature, and pseudo-likelihood. Applications are provided with social science problems by analyzing the effect of mental health and life satisfaction on volunteer activities from Korean welfare panel data; in addition, we observe that the inclusion of random effects in the model leads to improved analyses with more reasonable inferences.