• Title/Summary/Keyword: 3D approximation

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Residual Stress Estimation and Deformation Analysis for Injection Molded Plastic Parts using Three-Dimensional Solid Elements (3 차원 입체요소를 사용한 사출성형품의 잔류응력 예측 및 후변형 해석)

  • Park, Keun;Ahn, Jong-Ho;Yim, Chung-Hyuk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.4
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    • pp.507-514
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    • 2003
  • Most of CAE analyses for injection molding have been based on the Mele Shaw's approximation: two-dimensional flow analysis. in some cases, that approximation causes significant errors due to loss of the geometrical information as well as simplification of the flow characteristics in the thickness direction. Although injection molding analysis software using three-dimensional solid elements has been developed recently, such as Moldflow Flow3D, it does not contain a deformation analysis function yet. The present work covers three-dimensional deformation analysis or injection molded plastic parts using solid elements. A numerical scheme for deformation analysis has bun proposed from the results of injection molding analysis using Moldflow Flow3D. The accuracy of the proposed approach has been verified through a numerical analysis of rectangular plates with various thicknesses in comparison with the classical shell-based approach. In addition, the reliability of the approach has also been proved through an industrial example. an optical plastic lens, in comparison of real experiments.

Comparison of the 2D/3D Acoustic Full-waveform Inversions of 3D Ocean-bottom Seismic Data (3차원 해저면 탄성파 탐사 자료에 대한 2차원/3차원 음향 전파형역산 비교)

  • Hee-Chan, Noh;Sea-Eun, Park;Hyeong-Geun, Ji;Seok-Han, Kim;Xiangyue, Li;Ju-Won, Oh
    • Geophysics and Geophysical Exploration
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    • v.25 no.4
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    • pp.203-213
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    • 2022
  • To understand an underlying geological structure via seismic imaging, the velocity information of the subsurface medium is crucial. Although the full-waveform inversion (FWI) method is considered useful for estimating subsurface velocity models, 3D FWI needs a lot-of computing power and time. Herein, we compare the calculation efficiency and accuracy of frequency-domain 2D and 3D acoustic FWIs. Thereafter, we demonstrate that the artifacts from 2D approximation can be partially suppressed via frequency-domain 2D FWI by employing diffraction angle filtering (DAF). By applying DAF, which employs only big reflection angle components, the impact of noise and out-of-plane reflections can be reduced. Additionally, it is anticipated that the DAF can create long-wavelength velocity structures for 3D FWI and migration.

Recovery of 3-D Motion from Time-Varying Image Flows

  • Wohn, Kwang-Yun;Jung, Soon-Ki
    • Journal of Electrical Engineering and information Science
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    • v.1 no.2
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    • pp.77-86
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    • 1996
  • In this paper we deal with the problem of recovering 3-D motion and structure from a time-varying 2-D velocity vector field. A great deal has been done on this topic, most of which has concentrated on finding necessary and sufficient conditions for there to be a unique 3-D solution corresponding to a given 2-D motion. While previous work provides useful theoretical insight, in most situations the known algorithms have turned out to be too sensitive to be of much practical use. It appears that any robust algorithm must improve the 3-D solutions over time. As a step toward such algorithm, we present a method for recovering 3-D motion and structure from a given time-varying 2-D velocity vector field. The surface of the object in the scene is assumed to be locally planar. It is also assumed that 3-D velocity vectors are piecewise constant over three consecutive frames (or two snapshots of flow field). Our formulation relates 3-D motion and object geometry with the optical flow vector as well as its spatial and temporal derivatives. The linearization parameters, or equivalently, the first-order flow approximation (in space and time) is sufficient to recover rigid body motion and local surface structure from the local instantaneous flow field. We also demonstrate, through a sensitivity analysis carried out for synthetic and natural motions in space, that 3-D motion can be recovered reliably.

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Issues on the Machining of 3D-Profile for Automotive Press Dies (자동차 프레스 금형을 위한 3차원 윤곽가공의 문제점)

  • 이상헌;정연찬;주상윤
    • Korean Journal of Computational Design and Engineering
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    • v.7 no.3
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    • pp.141-147
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    • 2002
  • Profile machining using cutter diameter compensation is widely used in die and mould manufacturing. Especially automotive die makers try to use 3D-profile machining for trimming or flange dies. But the technological requirements and implementation issues haven't been defined. In this paper we summarized the requirements and issues of 3D-profile machining. Approximation of input profiles into sequences of line and helical arc is the first major issue. The second major issue is removing cutter inter- ference from the approximated curves holding z-values when the maximum cutter diameter is given. Keeping constant machining width, local machining, path linking problems and several detail technological requirements are also discussed.

Development of 3-D Volume PIV (3차원 Volume PIV의 개발)

  • Choi, Jang-Woon;Nam, Koo-Man;Lee, Young-Ho;Kim, Mi-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.6
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    • pp.726-735
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    • 2003
  • A Process of 3-D Particle image velocimetry, called here, as '3-D volume PIV' was developed for the full-field measurement of 3-D complex flows. The present method includes the coordinate transformation from image to camera, calibration of camera by a calibrator based on the collinear equation, stereo matching of particles by the approximation of the epipolar lines, accurate calculation of 3-D particle positions, identification of velocity vectors by 3-D cross-correlation equation, removal of error vectors by a statistical method followed by a continuity equation criterior, and finally 3-D animation as the post processing. In principle, as two frame images only are necessary for the single instantaneous analysis 3-D flow field, more effective vectors are obtainable contrary to the previous multi-frame vector algorithm. An Experimental system was also used for the application of the proposed method. Three analog CCD camera and a Halogen lamp illumination were adopted to capture the wake flow behind a bluff obstacle. Among 200 effective particle s in two consecutive frames, 170 vectors were obtained averagely in the present study.

Analysis of 3-D Superplastic Forming/Diffusion Bonding Process Using a Hierarchical Contact Searching Method(I) (계층적 접촉 탐색방법을 이용한 3-D 초소성 성형/확산접합의 공정설계(I))

  • Kang, Y.K.;Song, J.S.;Hong, S.S.;Kwon, Y.N.;Lee, J.H.;Kim, Y.H.
    • Transactions of Materials Processing
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    • v.16 no.2 s.92
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    • pp.138-143
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    • 2007
  • Superplastic forming/diffusion bonding (SPF/DB) processes were analyzed using a 3-D rigid visco-plastic finite element method. A constant-triangular element based on membrane approximation and an incremental theory of plasticity are employed for the formulation. The coulomb friction law is used for interface friction between tool and material. Pressure-time relationship for a given optimal strain rate is calculated by stress and pressure values at the previous iteration step. In order to improve the contact searching, hierarchical search algorithm has been applied and implemented into the code. Various geometries including sandwich panel and 3 sheet shape for 3-D SPF/DB model are analyzed using the developed program. The validity fer the analysis is verified by comparison between analysis and results in the literature.

A study on the nonlinear error correction of the phase measuring profilometry (PMP 형상 측정법에서 비선형 오차보정에 관한 연구)

  • 황용선;강영준;박낙규;백성훈
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.513-516
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    • 2003
  • Phase Measuring Profilometry(PMP) has been developed as one of three dimensional 3-D shape measuring methods. The 3-D profile of an object was calculated from the phase data obtained by the sinusoidal patterns projected on the object. However, in some cases the approximation includes considerable errors. In this paper, the effect on the errors caused by the optical geometry and the calibration procedure in PMP technique are discussed. The errors which occured in the process of calculating the 3-D profile from the phase distribution are investigated theoritically and experimentally.

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Issues on the Machining of 3D-Profile for Automotive Press Dies (자동차 프레스 금형을 위한 3차원 윤곽가공의 문제점)

  • Lee S. H.;Chung Y. C.;Ju S. Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2002.02a
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    • pp.19-25
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    • 2002
  • Profile machining using cutter diameter compensation is widely used in die and mould manufacturing. Especially automotive die makers try to use 3D-profile machining for trimming or flange dies. But the technological requirements and implementation issues haven't been defined. In this paper we summarized the requirements and issues of 3D-profile machining. Approximation of input profiles into sequences of line and helical arc is the first major issue. The second major issue is removing cutter interference from the approximated curves holding z-values when the maximum cutter diameter is given. Keeping constant machining width, local machining, path linking problems and several detail technological requirements are also discussed.

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An Adaptive Classifier for 3-D Planar Object Recognition Based on Uncertainty of Features by Binocular Stereo Method (Binocular Stereo 방법에 의한 3차원 평면 물체의 특징값의 불확실성을 고려한 적응분류기)

  • 권중장;김성대
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.30B no.4
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    • pp.92-103
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    • 1993
  • In this paper, we propose an adaptive classifier based on uncertainty of features for 3D planar object recognition. First, we investigate the uncertainty of depth information and the feature values of 3D planar object by numerical method. And, we observed that the statistical behavior of feature is dependent on the position and orientation of objects. After that, the approximation of the statistical behavior is executed. Subsequently, the recognition procedure is executed by the adaptive classifier. By computer simulation, we confirmed that the proposed classifier is useful for 3D planar object recognition.

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First-principles Study on Magnetism and Electronic Structure of Fe Chain on Ag(001) (Ag(001) 표면 위에 놓인 Fe 선의 자성과 전자구조)

  • Jin, Y.J.;Lee, J.I.
    • Journal of the Korean Magnetics Society
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    • v.15 no.4
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    • pp.217-220
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    • 2005
  • The electronic structure and magnetism of Fe chain along the [110] direction on Ag(001) were investigated by using the all-electron full-potential linearized augmented plane wave (FLAPW) method within generalized gradient approximation (GGA). The magnetic moment of Fe atom in Fe chain is calculated to be $3.02\;{\mu}_B$, which is slightly larger than that ($2.99\;{\mu}_B$) of the Fe[110] chain on Cu(001). The reduced coordination number for the Fe chain induced the Fe-d band narrowing and exchange-splitting enhancement, which are responsible for the large magnetic moment of the Fe chain. The calculated band width of the Fe-d band and the exchange-splitting are 1.7 eV and 3.2 eV, respectively.