• Title, Summary, Keyword: Local Approach

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On Practical Efficiency of Locally Parametric Nonparametric Density Estimation Based on Local Likelihood Function

  • Kang, Kee-Hoon;Han, Jung-Hoon
    • Communications for Statistical Applications and Methods
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    • v.10 no.2
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    • pp.607-617
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    • 2003
  • This paper offers a practical comparison of efficiency between local likelihood approach and conventional kernel approach in density estimation. The local likelihood estimation procedure maximizes a kernel smoothed log-likelihood function with respect to a polynomial approximation of the log likelihood function. We use two types of data driven bandwidths for each method and compare the mean integrated squares for several densities. Numerical results reveal that local log-linear approach with simple plug-in bandwidth shows better performance comparing to the standard kernel approach in heavy tailed distribution. For normal mixture density cases, standard kernel estimator with the bandwidth in Sheather and Jones(1991) dominates the others in moderately large sample size.

The Analysis of Welding Deformation in Large Welded Structure by Using Local & Global Model (Local & Global 모델을 이용한 용접구조물 변형 해석에 관한 연구)

  • Jang Kyoung-Bok;Cho Si-Hoon;Jang Tae-Won
    • Journal of Welding and Joining
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    • v.22 no.6
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    • pp.25-29
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    • 2004
  • Some industrial steel structures are composed by components linked by several welding joints to constitute an assembly. The main interest of assembly simulation is to evaluate the global distortion of welded structure. The general method, thermo-elasto-plastic analysis, leads to excessive model size and computation time. In this study, a simplified method called "Local and Global approach" was developed to break down this limit and to provide a accurate solution for distortion. Local and global approach is composed of 3 steps; 1) Local simulation of each welding joint on a dedicated mesh (usually very fine due to high thermal gradients), taking into account for the non linearity of the material properties and the moving heat source. 2) Transfer to the global model of the effects of the welding joints by projection of the plastic strain tensors. 3) Elastic simulation to determine final distortions in global model. The welding deformation test for mock-up structure was performed to verify this approach. The predicted welding distortion by this approach had a good agreement with experiment results.

Fatigue Life Analysis of Butt-welded specimen by Local Strain Approach (국부변형률방법을 이용한 용접시험편의 피로수명 해석)

  • Lee Dong-Hyong;Seo Jung-Won;Goo Byeong-choon;Seok Chang-Sung
    • Proceedings of the KSR Conference
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    • pp.73-78
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    • 2003
  • The residual stresses and. distortions of structures by welding exert negative effect on the safety of railroad structures. This investigation performs a thermal elasto-plastic analysis using finite element techniques to evaluate residual stresses in butted-welded joint. Considering this initial residual stresses, local stress and strain at the critical location (weld toe) during the loading were analyzed by elastic plastic finite element analysis. Fatigue crack initiation life and fatigue crack propagation life of butt-welded specimen were predicted by local strain approach and Neuber's role and Paris law. It is demonstrated that fatigue life estimates by local strain approach closely approximate the experimental results.

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PARALLEL COMPUTATIONAL APPROACH FOR THREE-DIMENSIONAL SOLID ELEMENT USING EXTRA SHAPE FUNCTION BASED ON DOMAIN DECOMPOSITION APPROACH

  • JOO, HYUNSHIG;GONG, DUHYUN;KANG, SEUNG-HOON;CHUN, TAEYOUNG;SHIN, SANG-JOON
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.24 no.2
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    • pp.199-214
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    • 2020
  • This paper describes the development of a parallel computational algorithm based on the finite element tearing and interconnecting (FETI) method that uses a local Lagrange multiplier. In this approach, structural computational domain is decomposed into non-overlapping sub-domains using local Lagrange multiplier. The local Lagrange multipliers are imposed at interconnecting nodes. 8-node solid element using extra shape function is adopted by using the representative volume element (RVE). The parallel computational algorithm is further established based on message passing interface (MPI). Finally, the present FETI-local approach is implemented on parallel hardware and shows improved performance.

A Structural Representation of Handwritings for Automatic On-line Signature Verification (온라인 서명 검증을 위한 필기의 구조적 표현)

  • Kim, Seong-Hoon
    • Journal of the Korea Society for Simulation
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    • v.14 no.3
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    • pp.147-154
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    • 2005
  • In conventional approaches such as a functinal approach or a parametric approach to online signature verification, which could not deal with the local shape of signature, much various important informations inherent in the local part of signature shape have been overlooked. In this paper, we try a structural approach in which a signature is represented as a structural form of handwriting primitives and the local parts along a signature handwriting can be selectively compared according to their discrimination power in the process of signature verification, As a result, the error rate is diminished in the case that the weights of subpattern units is applied into comparing process, which is the degree of discrimination power of local part. And also, the global variation and complexity of each signature extracted from the analysis of local shape is found useful in determining the decision threshold more precisely.

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Damage identification of substructure for local health monitoring

  • Huang, Hongwei;Yang, Jann N.
    • Smart Structures and Systems
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    • v.4 no.6
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    • pp.795-807
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    • 2008
  • A challenging problem in structural damage detection based on vibration data is the requirement of a large number of sensors and the numerical difficulty in obtaining reasonably accurate results when the system is large. To address this issue, the substructure identification approach may be used. Due to practical limitations, the response data are not available at all degrees of freedom of the structure and the external excitations may not be measured (or available). In this paper, an adaptive damage tracking technique, referred to as the sequential nonlinear least-square estimation with unknown inputs and unknown outputs (SNLSE-UI-UO) and the sub-structure approach are used to identify damages at critical locations (hot spots) of the complex structure. In our approach, only a limited number of response data are needed and the external excitations may not be measured, thus significantly reducing the number of sensors required and the corresponding computational efforts. The accuracy of the proposed approach is illustrated using a long-span truss with finite-element formulation and an 8-story nonlinear base-isolated building. Simulation results demonstrate that the proposed approach is capable of tracking the local structural damages without the global information of the entire structure, and it is suitable for local structural health monitoring.

Local Influence Approach Diagnostics for Optimal Experimental Design (최적 실험계획법에 대한 Local Influence Approach 진단방법)

  • 김영일
    • The Korean Journal of Applied Statistics
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    • v.4 no.2
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    • pp.195-207
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    • 1991
  • We consider the development of simple regression-like diagnostics for assessing the sensitivity of an optimal design to deviations from the assumptions of constant error variance. This contains a review of Cook's local influence approach and an application of local influence aproach to D-optimal experimental design. The method is applied in a number of simple examples in Section 3. Conclusions and directions for further research follow in Section 4.

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Unstructured discretisation of a non-local transition model for turbomachinery flows

  • Ferrero, Andrea;Larocca, Francesco;Bernaschek, Verena
    • Advances in aircraft and spacecraft science
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    • v.4 no.5
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    • pp.555-571
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    • 2017
  • The description of transitional flows by means of RANS equations is sometimes based on non-local approaches which require the computation of some boundary layer properties. In this work a non-local Laminar Kinetic Energy model is used to predict transitional and separated flows. Usually the non-local term of this model is evaluated along the grid lines of a structured mesh. An alternative approach, which does not rely on grid lines, is introduced in the present work. This new approach allows the use of fully unstructured meshes. Furthermore, it reduces the grid-dependence of the predicted results. The approach is employed to study the transitional flows in the T106c turbine cascade and around a NACA0021 airfoil by means of a discontinuous Galerkin method. The local nature of the discontinuous Galerkin reconstruction is exploited to implement an adaptive algorithm which automatically refines the mesh in the most significant regions.

A Study of Fatigue Life Prediction for Automotive Spot Weldment Using Local Strain Approach (국부변형률근사법을 이용한 차체 점용접부의 피로수명 예측에 관한 연구)

  • Lee, Song-In;Gwon, Il-Hyeon;Lee, Beom-Jun;Yu, Hyo-Seon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.2
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    • pp.220-227
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    • 2001
  • The fatigue crack initiation life is studied on automotive tensile-shear spot weldment made from cold rolled carbon steel(SPC) sheet by using DCPDM and local strain approach. It can be found that the fatigue crack initiation behavior in spot weldment can be definitely detected by DCPDM system. To predict the fatigue life of spot weldment, the local stresses and strains at the potential critical region are estimated by approximate method based on Neubers rule and elastic-plastic FEM analysis. A satisfactory correlation between the predicted life obtained from Local strain approach based on Neubers rule and experimental life can be found in spot weldment within a factor of 2.

Derivational approach and representational approach in generative grammar (생성문법에서 도출적 접근과 표시적 접근)

  • Choe, Sook-Hee
    • English Language & Literature Teaching
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    • v.10 no.1
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    • pp.179-200
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    • 2004
  • The purpose of this study is to investigate the adequacy of derivational approach and representational approach to syntactic theories in generative grammar. As the generative grammar is based on the derivational process of syntactic theories, it is suggested that derivational approach is more valid than representational approach. Move, Economy Principle, Local Economy and Label-free Phrase Structure in Minimalist framework support the preference of derivational approach to representational approach with the elimination of computational complexity, minimality, and label-free phrase structure. Syntactic structure is considered as the result of the interaction of the properties of lexical items containing probe and economy conditions constrained by bare output conditions. On the other hand, Pseudogapping in Lasnik(1999) is analyzed in terms of Object Shift, that is, overt raising to Spec of $Agr_o$ and the PF deletion of VP in representational approach. Hence, it is suggested that the combination of derivational and representational approaches to syntactic theories can be admitted in generative grammar.

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