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An ALE Finite Element Formulation for Rigid-Viscoplatic Materials and Its Application to Axisymmetric Extrusion through Square Dies (ALE 묘사에 근거한 강-점소성 유한요소 수식화와 축대칭 평금형 압출에의 적용)

  • 강연식;양동열
    • Transactions of Materials Processing
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    • v.3 no.2
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    • pp.156-166
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    • 1994
  • An arbitrary Lagrangian-Eulerian (ALE) finite element method has been developed. The finite element formation is derived and implemented for rigid-viscoplastic materials. The developed computer program is applied to the analysis of axisymmetric square die extrusion, which has many difficulties with updated Lagrangian approach. The results are compared with those from updated Largrangian approach. The results are compared with those from updated Lagrangian finite element program. Updating scheme of time dependent variables and mesh control are also examined.

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FE model updating method incorporating damping matrices for structural dynamic modifications

  • Arora, Vikas
    • Structural Engineering and Mechanics
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    • v.52 no.2
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    • pp.261-274
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    • 2014
  • An accurate finite element (FE) model of a structure is essential for predicting reliably its dynamic characteristics. Such a model is used to predict the effects of structural modifications for dynamic design of the structure. These modifications may be imposed by design alterations for operating reasons. Most of the model updating techniques neglect damping and so these updated models can't be used for accurate prediction of vibration amplitudes. This paper deals with the basic formulation of damped finite element model updating method and its use for structural dynamic modifications. In this damped damped finite element model updating method, damping matrices are updated along with mass and stiffness matrices. The damping matrices are updated by updating the damping coefficients. A case involving actual measured data for the case of F-shaped test structure, which resembles the skeleton of a drilling machine is used to evaluate the effectiveness of damped FE model updating method for accurate prediction of the vibration levels and thus its use for structural dynamic modifications. It can be concluded from the study that damped updated FE model updating can be used for structural dynamic modifications with confidence.

Finite Element Analysis Piezocone Test I (피에조콘 시험의 유한요소 해석 I)

  • 김대규
    • Journal of the Korean Geotechnical Society
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    • v.16 no.4
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    • pp.183-190
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    • 2000
  • In this research, the finite element analysis of piezocone penetration and dissipation tests have been conducted using the anisotropic elastoplastic-viscoplastic bounding surface model in the Updated Lagrangian reference frame for the large deformation and finite strain nu\ature of piezocone penetration. Accordingly, virtual work equation and corresponding finite element equations have been reformulated. Theory of mixtures has been incorporated to explain the behavior of the sol. It has been observed that the viscoplastic part of the soil model affected the whole formulation. The results of the finite element analysis have been compared and investigated with the experimental results. The formulations and the results are described in part 'I' and part 'II', respectively.

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An Optimized Cache Coherence Protocol in Multiprocessor System Connected by Slotted Ring (슬롯링으로 연결된 다중처리기 시스템에서 최적화된 캐쉬일관성 프로토콜)

  • Min, Jun-Sik;Chang, Tae-Mu
    • The Transactions of the Korea Information Processing Society
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    • v.7 no.12
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    • pp.3964-3975
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    • 2000
  • There are two policies for maintaining consistency among the multiple processor caches in a multiprocessor system: Write invalidate and Write update. In the write invalidate policy, whenever a processor attempt to write its cached block, it has to invalidate all the same copies of the updated block in the system. As a results of this frequent invalidations, this policy results in high cache miss ratio. On the other hand, the write update policy renew them, instead of invalidating all the same copies. This policy has to transfer the updated contents through interconnection network, whether the updated block is ptivate or not. Therefore the network suffer from heavy transaction traffic. In this paper we present an efficient cache coherence protocol for shared memory multiprocessor system connected by slotted ring. This protocol is based on the write update policy, but the updated contents are transferred only in case of updating the shared block. Otherwise, if the updated block is private, the updated contents are not transferred. We analyze the proposed protocol and enforce simulation to compare it with previous version.

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A Study on Updated Object Detection and Extraction of Underground Information (지하정보 변화객체 탐지 및 추출 연구)

  • Kim, Kwangsoo;Lee, Heyung-Sub;Kim, Juwan
    • Journal of Software Assessment and Valuation
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    • v.16 no.2
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    • pp.99-107
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    • 2020
  • An underground integrated map is being built for underground safety management and is being updated periodically. The map update proceeds with the procedure of deleting all previously stored objects and saving newly entered objects. However, even unchanged objects are repeatedly stored, deleted, and stored. That causes the delay of the update time. In this study, in order to shorten the update time of the integrated map, an updated object and an unupdated object are separated, and only updated objects are reflected in the underground integrated map, and a system implementing this technology is described. For the updated object, an object comparison method using the center point of the object is used, and a quad tree is used to improve the search speed. The types of updated objects are classified into addition and deletion using the shape of the object, and change using its attributes. The proposed system consists of update object detection, extraction, conversion, storage, and history management modules. This system has the advantage of being able to update the integrated map about four times faster than the existing method based on the data used in the experiment, and has the advantage that it can be applied to both ground and underground facilities.

Review on the Updated ISBP 2007 (2007 국제표준은행관행에 반영된 업데이트 내용의 검토)

  • Kang, Won-Jin
    • THE INTERNATIONAL COMMERCE & LAW REVIEW
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    • v.38
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    • pp.97-121
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    • 2008
  • The updated International Standard Banking Practice(ISBP), International Chamber of Commerce Publication No. 681, was published to bring its contents in line with UCP 600. The ISBP 681 has dealt with 185 paragraphs from paragraphs 200 of ISBP 645 that are commonly arising in the credit transactions and also explains in detail some of the articles of UCP 600 with the proper interpretation. The updated version ISBP 681 involved aligning it with UCP 600, making certain technical adjustments in expression of words such as "in conflict" instead of "inconsistent", etc. Also descriptions of goods in commercial invoice to be altered the words into "services or performance" in addition to "goods". Despite the updated ISBP 681, there remains a question. Where the words "from" or "after" are used in regard to something other than a period of shipment or the maturity date of drafts, there is no guidance from the UCP as to its meaning. The party concerned in credit transactions is also required to have a full understanding of the paragraphs of ISBP 681 and the articles of UCP 600 in order to acquire the documents preparation and examination facilitating the parties to minimize discrepancies.

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Update the finite element model of Canton Tower based on direct matrix updating with incomplete modal data

  • Lei, Y.;Wang, H.F.;Shen, W.A.
    • Smart Structures and Systems
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    • v.10 no.4_5
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    • pp.471-483
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    • 2012
  • In this paper, the structural health monitoring (SHM) benchmark problem of the Canton tower is studied. Based on the field monitoring data from the 20 accelerometers deployed on the tower, some modal frequencies and mode shapes at measured degrees of freedom of the tower are identified. Then, these identified incomplete modal data are used to update the reduced finite element (FE) model of the tower by a novel algorithm. The proposed algorithm avoids the problem of subjective selection of updated parameters and directly updates model stiffness matrix without model reduction or modal expansion approach. Only the eigenvalues and eigenvectors of the normal finite element models corresponding to the measured modes are needed in the computation procedures. The updated model not only possesses the measured modal frequencies and mode shapes but also preserves the modal frequencies and modes shapes in their normal values for the unobserved modes. Updating results including the natural frequencies and mode shapes are compared with the experimental ones to evaluate the proposed algorithm. Also, dynamic responses estimated from the updated FE model using remote senor locations are compared with the measurement ones to validate the convergence of the updated model.

A Design and Implementation of Functional Array for Improvement of the Traversal Time (탐색시간의 개선을 위한 함수형 배열의 설계 및 구현)

  • Ju, Hyeong-Seok;Yu, Won-Hui
    • The Transactions of the Korea Information Processing Society
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    • v.3 no.5
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    • pp.1262-1272
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    • 1996
  • Pure functional languages have the referential transparency feature sothat all objects cannot be updated destuctively. Once an aggregated data structure such as array is updated, both the original and newly updated array must be preserved to maintain reverential transparency. Thus, it is required to develop an efficient mechanism with which can reduce the maintenance cost while maintaining referential transparency for whole data. This study is to suggest a functional array to solve the problem, and them test it. For that, the proposed mechanism was implemented on a combinator graph reduction machine. The result shows that proposed mechanism reduces traversal time for array operations. Also, updating all versions and accessing the recent version are achieved in constant time without reconstruction of updated data in execution time.

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FE MODEL UPDATING OF ROTOR SHAFT USING OPTIMIZATION TECHNIQUES (최적화 기법을 이용한 로터 축 유한요소모델 개선)

  • Kim, Yong-Han;Feng, Fu-Zhou;Yang, Bo-Suk
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.104-108
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    • 2003
  • Finite element (FE) model updating is a procedure to minimize the differences between analytical and experimental results, which can be usually posed as an optimization problem. This paper aims to introduce a hybrid optimization algorithm (GA-SA), which consists of a Genetic algorithm (GA) stage and an Adaptive Simulated Annealing (ASA) stage, to FE model updating for a shrunk shaft. A good agreement of the first four natural frequencies has been achieved obtained from GASA based updated model (FEgasa) and experiment. In order to prove the validity of GA-SA, comparisons of natural frequencies obtained from the initial FE model (FEinit), GA based updated model (FEga) and ASA based updated model (FEasa) are carried out. Simultaneously, the FRF comparisons obtained from different FE models and experiment are also shown. It is concluded that the GA, ASA, GA-SA are powerful optimization techniques which can be successfully applied to FE model updating, the natural frequencies and FRF obtained from all the updated models show much better agreement with experiment than that obtained from FEinit model. However, FEgasa is proved to be the most reasonable FE model, and also FEasa model is better than FEga model.

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