• 항공우주시스템공학회지
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• 제7권2호
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• pp.1-7
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• 2013

Recently, there are a number of studies over dynamic analysis for minimizing vibration of flexible structures such as solar panel for agility of high-agility satellite. The traditional studies perform dynamic analysis of a solar panel assumed as rigid structure since the stiffness of solar panel is higher than the stiffness of solar panel's hinge spring. However, there are vibrations that have modes of bending and torsion when high-agility satellite rotate speedily. This vibrations result in delaying safety time of satellite or degrading image quality. This paper presents dynamic analysis's technique of satellites including the spring hinge of solar panel and flexible structural solar panel's effects described as the linear equation of motion using Lagrange's theorem, and verifies the validity of an established dynamic analysis's technique of satellites by comparing the finite element method. In addition high-agility satellite's dynamic characteristics of a torque profile are analyzed from the established dynamic analysis's technique of satellites.

• 한국철도학회논문집
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• 제9권6호
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• pp.717-724
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• 2006

The major objective of this study is to investigate the effects and application of improvement for railway steel plate girder bridge by resilient panel track system. It analyzed the mechanical behaviors of steel plate girder bridge with applying resilient panel track system on the finite element analysis and laboratory test for static & dynamic characteristics. As a result, the improvement of steel plate girder bridge with resilient panel track systems are obviously effective for the static & dynamic response which is non-ballast steel plate girder bridge. The analytical and experimental study are carried out to investigate resilient panel track system decrease vertical acceleration and deflection on steel plate girder bridge for serviceability. And the resilient panel track system reduced dynamic maximum displacements (about 59%) and stresses (about 82%), the increase of dynamic safety is predicted by adopting resilient panel track system. From the dynamic test results of steel plate girder bridge, it is investigated that vertical acceleration and deflection is very low with applying resilient panel track system. The servicing steel plate girder bridge with resilient panel track system has need of the reasonable improvement measures which could be reducing the effect of static and dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.437-446
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• 2006

The major objective of this study is to investigate the effects and application of improvement for railway steel plate girder bridge by resilient panel track system. It analyzed the mechanical behaviors of steel plate girder bridge with applying resilient panel track system on the finite element analysis and laboratory test for static & dynamic characteristics. As a result, the improvement of steel plate girder bridge with resilient panel track systems are obviously effective for the static & dynamic response which is non-ballast steel plate girder bridge. The analytical and experimental study are carried out to investigate resilient panel track system decrease vertical acceleration and deflection on steel plate girder bridge for serviceability. And the resilient panel track system reduced dynamic maximum displacements(about 59%) and stresses(about 82%), the increase of dynamic safety is predicted by adopting resilient panel track system. From the dynamic test results of steel plate girder bridge, it is investigated that vertical acceleration and deflection is very low with applying resilient panel track system. The servicing steel plate girder bridge with resilient panel track system has need of the reasonable improvement measures which could be reducing the effect of static and dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

• 대한기계학회논문집A
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• 제22권2호
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• pp.380-390
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• 1998

In the present work a finite element formulation using dynamic explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and linearizing dynamic formulation. A contact scheme is developed by combining the skew boundary condition and direct trial-and-error method. In this work, for economic analysis the faster punch velocity and the mass scaling method are introduced. To investigate the effects of punch velocity and mass scaling, the various values of punch velocity and the various mass scalings are used for numerical analysis. Computations are carried out for analysis of complicated auto-body panel stamping processes such as forming of an oil pan and a fuel tank.

• 한국정밀공학회지
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• 제21권10호
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• pp.115-126
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• 2004

In the present work a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation. Analyzed auto-body panel stomping process correction of forming using software called Dynaform using dynamic extensive method. Further, the simulated results for the auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.

• 한국기계가공학회지
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• 제3권4호
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• pp.63-72
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• 2004

In this paper, a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation. Auto-body panel forming is analyzed by using dynamic-explicit finite element method. Further, the simulated results of the auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the stamping industrial area for the cost reduction, weight saving, and improvement of strength.

• International Journal of Aeronautical and Space Sciences
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• 제17권4호
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• pp.476-490
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• 2016

This paper defines mode shape function of a composite solar panel assumed as Kirchhoff-Love plate for considering a torsional mode of composite solar panel. It then goes on to define dynamic model of a high-agility satellite considering the flexibility of composite solar panel as well as stiffness of a solar panel's hinge using Lagrange's theorem, Ritz method and the mode shape function. Furthermore, this paper verifies the validity of dynamic model by comparing numerical results from the finite element analysis. In addition, this paper performs a dynamic response analysis of a rigid satellite which includes only natural modes for solar panel's hinges and a flexible satellite which includes not only natural modes of solar panel's hinges, but also structural modes of composite solar panels. According to the results, we confirm that the torsional mode of solar panel should be considered for the structural design of high-agility satellite. Finally, we performed optimization of high-agility satellite for minimizing mass with solar panel's area limit using the defined dynamic model. Consequently, we observed that the defined dynamic model for a high-agility satellite and result of the optimal design are very useful not only because of their optimal structural design but also because of the dynamic analysis of the satellite.

• 노동경제논집
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• 제32권2호
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• pp.95-124
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• 2009

본 연구는 외환위기 이후 상장제조기업의 생산성 추이 및 교육훈련효과를 분석하였다. 분석 결과, 외환위기 이후 상장제조기업은 시간이 흐를수록 저 생산성 국면에 빠지게 되었으며, 그 과정에서 상장제조기업의 고용 없는 성장, 물적 투자 없는 성장, 인적자본투자 없는 성장 현상이 관찰되었다. 그리고 생산성이 높은 기업의 고용비중이 늘고, 낮은 기업의 고용비중이 주는 효율적인 노동시장이 거의 작동하지 않았다. 또한 교육훈련이 생산성에 미치는 영향을 분석해 보기 위해 동적 패널 분석을 실시할 경우 교육훈련의 과소투자가 발생하고 있음에도 불구하고 교육훈련의 생산성에 대한 지나치게 높은 긍정적 효과가 나타나는 모순적 현상이 상당 부분 해결되었다.

• 한국자동차공학회논문집
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• 제4권5호
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• pp.16-25
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• 1996

In the present work a rigid-plastic finite element formulation using dynamic explicit time integration scheme is proposed for numerical analysis of auto-body panel stamping processes. The rigid-plastic finite element method based on membrane elements has long been employed as a useful numerical technique for the analysis of sheet metal forming because of its time effectiveness. A damping scheme is proposed in order to achieve a stable solution procedure in dynamic sheet forming problems. In order to improve the drawbacks of the conventional membrane elements, BEAM(abbreviated from Bending Energy Augmented Membrane) elements are employed. Rotational damping and spring about the drilling direction are introduced to prevent a zero energy mode. The lumping scheme is employed for the diagonal mass matrix and linearizing dynamic formulation. A contact scheme is developed by combining the skew boundary condition and the direct trial-and-error method. Computations are carried out for analysis of complicated auto-body panel stamping processes such as forming of an oilpan, a fuel tank and a front fender. The numerical results of explicit analysis are compared with the implicit results with good agreements and it is shown that the explicit scheme requires much shorter computational time, especially when the problem becomes more complicated. It is thus shown that the proposed dynamic explicit rigid-plastic finite element method enables an effective computation for complicated autobody panel stamping processes.

• 자원ㆍ환경경제연구
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• 제18권1호
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• pp.53-73
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• 2009

본 연구는 1971년부터 2002년까지 의무감축국과 비의무감축국의 이산화탄소 배출량에 대한 ${\beta}$-수렴성을 검정하였다. 이를 위해서 Barro and Sala-i-Martin (1995)의 경제성장 수렴성 이론을 확장하였고 기존의 정태적 패널 방법이 아닌 종속변수의 시차변수가 독립변수로 포함되는 동적패널분석 (dynamic panel analysis)과 패널 단위근 검정 (panel unit root test)을 시행하였다. 패널 단위근 검정의 경우, Levin et al. (2002) 와 Im et al. (2003) 두 가지 방법을 적용하였다. 연구 결과 의무감축국은 Levin et al. 방법으로 검정한 결과 단위근 존재가 기각되어 수렴성을 확인할 수 있었고 비의무감축국의 경우 Levin et al. 방법과 Im et al. 방법 모두에서 단위근 존재를 기각하지 못하여 수렴성이 존재하지 않음을 확인할 수 있었다. 또한 의무감축국가와 비의무감축국가의 ${\beta}$-수렴성 검정 결과 두 집단 모두 수렴성이 존재하지만 중국을 제외한 비의무감축국가의 경우 수렴성이 존재하지 않았다. 이는 중국의 기본 배출량이다 국가들보다 월등히 높기 때문에 전체 검정의 편의가 발생했을 것으로 생각되어 중국을 제외한 집단을 재검정한 결과 예상대로 수렴성이 존재하지 않는 것으로 나타났다.