• Title/Summary/Keyword: Adaptive plasticity

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Activity-dependent plasticity in skeletal muscle (골격근의 활동 의존적 가소성)

  • Kim, Sik-Hyun
    • PNF and Movement
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    • v.6 no.1
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    • pp.41-51
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    • 2008
  • Purpose : This paper reviews evidence supporting adaptive plasticity in skeletal muscle fibers induced by various exercise training and neuromuscular activity. Result : Skeletal muscle fiber demonstrates a remarkable adaptability and can adjust its physiologic and contractile makeup in response to alterations in functional demands. This adaptive plasticity results from the ability of muscle fibers to adjust their molecular, functional, and contractile properties in response to altered physiological demands, such as changes in exercise patterns and mechanical loading. The process of activity-dependent plasticity in skeletal muscle involves a multitude of signalling mechanisms initiating replication of specific genetic sequences, enabling subsequent translation of the genetic message and ultimately generating a series of myosin heavy chain isoform. Conclusions : Knowledge of the mechanisms and interaction of activity-dependent adaptive pathways in skeletal muscle is important for our understanding of the synthesis of muscle myosin protein, maintenance of metabolic and functional capacity with physical activity, and therapeutic intervention for functional improvement.

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Unsuspected Plasticity of Single Neurons after Connection of the Corticospinal Tract with Peripheral Nerves in Spinal Cord Lesions

  • Brunelli, Giorgio;Wild, Klaus von
    • Journal of Korean Neurosurgical Society
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    • v.46 no.1
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    • pp.1-4
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    • 2009
  • Objective: To report an unsuspected adaptive plasticity of single upper motor neurons and of primary motor cortex found after microsurgical connection of the spinal cord with peripheral nerve via grafts in paraplegics and focussed discussion of the reviewed literature. Methods: The research aimed at making paraplegics walk again, after 20 years of experimental surgery in animals. Amongst other things, animal experiments demonstrated the alteration of the motor endplates receptors from cholinergic to glutamatergic induced by connection with upper motor neurons. The same paradigm was successfully performed in paraplegic humans. The nerve grafts were put into the ventral-lateral spinal tract randomly, with out possibility of choosing the axons coming from different areas of the motor cortex. Results: The patient became able to selectively activate the re-innervated muscles she wanted without concurrent activities of other muscles connected with the same cortical areas. Conclusion: Authors believe that unlike in nerve or tendon transfers, where the whole cortical area corresponding to the transfer changes its function a phenomenon that we call "brain plasticity by areas". in our paradigm due to the direct connection of upper motor neurons with different peripheral nerves and muscles via nerve grafts motor learning occurs based on adaptive neuronal plasticity so that simultaneous contractions of other muscles are prevented. We propose to call it adaptive functional "plasticity by single neurons". We speculate that this phenomenon is due to the simultaneous activation of neurons spread in different cortical areas for a given specific movement, whilst the other neurons of the same areas connected with peripheral nerves of different muscles are not activated at the same time. Why different neurons of the same area fire at different times according to different voluntary demands remains to be discovered. We are committed to solve this enigma hereafter.

Analysis of Forming a Front Door Panel Including Trimming and Flanging (트리밍과 플랜징을 포함한 Front Door Panel 의 성형해석)

  • 김충식
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1999.03b
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    • pp.53.1-56
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    • 1999
  • Using a new dynamic-explicity program SAIT_STAMP the analysis of forming a front door panel is presented. The analysis consists of 7 processes including drawing trimming flanging and springback. From the analysis results it is shown that adaptive refinement scheme and robust trimming algorithm enable SAIT_STAMP to simulate the multi-stage forming of automotive parts with large and complex geometry.

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Intelligent Forging Simulation Techniques and AFDEX (지능적 단조 시뮬레이션 기술과 AFDEX)

  • Joun, M.S.;Lee, M.C.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.225-229
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    • 2008
  • We present an intelligent forging simulator AFDEX. The intelligent forging simulator is determined by the adaptive and optimal mesh generation technique and many intelligent application-oriented special functions which minimize the user-intervention during forging simulation. Of course, the solution accuracy should be optimized in the intelligent simulation. We have developed AFDEX to meet the requirement on intelligent simulation. Its characteristics are introduced with the help of typical application examples.

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Development of Feed-forward AGC using Adaptive Control Algorithm (적응기법을 이용한 Feed-forward AGC 기술 개발)

  • 홍성철;이영교
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.168-171
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    • 2003
  • Generally RF AGC (Roll Force Automatic Gauge Control) controls the roll gap using the variation of rolling force caused by the roll eccentricity and the entry thickness of material, but RE AGC takes the bad effect of the roll eccentricity. The Feed-forward (FF) AGC method, which controls the next stand roll gap by the estimation of the thickness variation due to skid mark is needed to supplement the shortage of RF AGC. In this paper, an adaptive filtering method which takes account of the kind of material, the final objective thickness and the rolling speed is proposed to predict skid mark thickness variation. In addition, an improved estimation method of control point using a speedometer and looper angle is suggested. Via on line test, the performance improvement of the suggested FF AGC method is verified.

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Adaptive Finite Element Analysis of an Enclosed Die Forging Process of a Bevel Gear and the Experimental Verification (베벨기어 폐쇄냉간단조 공정의 지능형 유한요소해석과 결과의 검증)

  • Lee M. C.;Part R. H.;Jun B. Y.;Joun M. S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.99-102
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    • 2005
  • An approach to adaptive finite element analysis of three-dimensional forging processes is presented in this paper. In the approach, an optimal tetrahedral element generation technique is employed and the mesh density is specified by the combination of the normalized effective strain and the normalized effective strain rate. The approach is applied to computer simulation of an enclosed die forging process of a bevel gear and its results are compared with experiments.

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AUTOMATED ADAPTIVE TETRAHEDRAL ELEMENT GENERATION FOR THREE-DIMENSIONAL METAL FORMING SIMULATION (삼차원 소성가공 공정 시뮬레이션을 위한 지능형 사면체 요소망 자동생성)

  • Lee M. C.;Joun M. S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.203-208
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    • 2005
  • In this paper, an automated adaptive mesh generation scheme, based on an advancing-front-Delaunay method, is developed for finite element simulation of three dimensional bulk metal forming processes. During the simulation, the finite element mesh system is adaptively remeshed whenever the mesh is unacceptable. Several schemes are developed such as curvature compensation scheme to minimize volume loss, optimal smoothing scheme to improve element quality, etc. The presented approach is evaluated and applied to automatic forging simulation in order to demonstrate the effect of the developed schemes.

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THREE-DIMENSIONAL METAL FORMING SIMULATION WITH AUTOMATED ADAPTIVE TETRAHEDRAL ELEMENT GENERATION (지능형 사면체 요소망 자동생성기법을 이용한 삼차원 소성가공 공정 시뮬레이션)

  • Lee M. C.;Joun M. S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.209-214
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    • 2005
  • In this paper, finite element simulation of three-dimensional bulk metal forming processes is performed by an automated adaptive tetrahedral mesh generation scheme. A dynamic data exchange scheme is employed between tetrahedral mesh generator and forging simulator to minimize user intervention. Both number of elements and density distributions are controlled by the octree technique. The presented approach is applied to automatic forging simulation in order to evaluate the efficiency of the developed schemes and the simulation results are compared with $DEFORM^{TM}$.

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An Effective mesh smoothing technique for the mesh constructed by the mesh compression technique (격자압축을 이용해 구성된 격자의 효과적인 격자유연화 방법)

  • 홍진태;이석렬;양동열
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.331-334
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    • 2003
  • In the finite element simulation of hot forging processes using hexahedron, remeshing of a flash is very difficult. The mesh compression method is a remeshing technique to construct an effective hexahedral mesh. However, because mesh is distorted during the compression procedure or the mesh compression method, mesh smoothing is necessary to improve the mesh Qualify. in this study, several geometric mesh smoothing techniques and a matrix norm optimization technique are applied and compared which is more adaptive to the mesh compression method.

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