• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.94-102
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• 2000

A computer program for three dimensional dynamic analysis of a mount system composed of rigid or flexible bodies and mount elements is developed. Cartesian coordinates and Euler parameters are used to specify the positions and orientations of the bodies. The equations of motion are formulated using Langrange equation and Langrange multiplier technique. The developed program includes routine, for inclined mount elements, several kinds of driving constrains, and external forces. The Static equilibrium analysis routine is also developed using iterative method.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.591-593
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• 2005

This paper presents the dynamic analysis of a humanoid robot using Nastran that is one of FEM analysis program. Generally, computer program based on the Lagrange-Euler method or Newton-Euler method was used for dynamic analysis of a robot. The Lagrange-Euler method requires much calculation performance and it is also hard to apply to complex structure, and the Newton-Euler method limits accurate modeling and calculation for closed structure like a humanoid robot. In this paper, mechanical and structural data are obtained from the Nastran. It is possible for Nastran to make model similar to real system and can apply a physical properties and laws to model. So, accurate simulation is possible. From this result, accurate data is gained by Nastran. Furthermore, this method is shown to be a useful method that guarantees accuracy for trajectory planning.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.325-327
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• 2004

The longitudinal instability (POGO) of the rocket should not be occurred during the whole flight time for the large class liquid propulsion system to complete a mission successfully. The longitudinal instability is caused by the resonance between the propulsion system and rocket structure in the low frequency range below 50Hz, ordinarily. Analysis on the low frequency dynamic characteristics on the liquid propulsion system with staged combustion cycle engine system was performed as a preliminary study on the longitudinal instability analysis.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.771-776
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• 2007

Widespread propagation of failure can be triggered by localized damage to a structure because of fires, impact and explosion etc. In this paper, the progressive collapse analysis program is developed to automatically check the failed members and construct the modified structural model at each step. OpenSees, that is widely used in many research groups, was used for the developed progressive collapse analysis control program. The control program developed in this study automatically computes the damage indices of all the structural members and performance a progressive collapse analysis after the first failed member is selected. Using the developed program, we compared the progressive collapse behaviors of the example structures considering dynamic effects or not, and the difference of progressive collapse mechanism according to the modeling method of the failed members.

• Journal of KIISE
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• v.41 no.10
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• pp.859-869
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• 2014

In recent years, the obfuscation techniques are commonly exploited to protect malwares, so obfuscated malwares have become a big threat. Especially, it is extremely hard to analyze virtualization-obfuscated malwares based on unusual virtual machines, because the original program is hidden by the virtual machine as well as its semantics is mixed with the semantics of the virtual machine. To confront this threat, we suggest a framework to analyze virtualization-obfuscated programs based on the dynamic analysis. First, we extract the dynamic execution trace of the virtualization-obfuscated executables. Second, we analyze the traces by translating machine instruction sequences into the intermediate representation and extract the virtual machine architecture by constructing dynamic context flow graphs. Finally, we extract abstract semantics of the original program using the extracted virtual machine architecture. In this paper, we propose a method to extract the information of the original program from a virtualization-obfuscated program by some commercial obfuscation tools. We expect that our tool can be used to understand virtualization-obfuscated programs and integrate other program analysis techniques so that it can be applied to analysis of the semantics of original programs using the abstract semantics.

• Journal of Digital Convergence
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• v.10 no.2
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• pp.63-71
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• 2012

This paper investigates efficiency analysis to IT HRD programs in the dynamic perspective. First, empirical result shows that government fund of IT research center is significantly associated with SCI thesis and the more trial goods and SW development is connected with the more patent and technology transfer. Second, ITRC program has been operated efficiently since 2000. Finally, dynamic efficiency analysis implicates that ITRC program is more efficient than other IT SoC program and foreign student support program. The reason why ITRC program is more efficient is generated not from the effect of imitation by catch-up strategy to developed HRD programs, but new operation system introducing and utilizing HRD performance system.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.5
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• pp.74-84
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• 1996

Dynamic loading of structures often causes excursions of stresses well into the inelastic range and the influence of geometric changes on the dynamic response is also significant in many cases. Therefore, both material and geometric nonlinearity effects should be considered in case that a dynamic load acts on the structure. For developing a program to analyze the dynamic response of an axisymmetric shell in this study, the material nonlinearity effect on the dynamic response was formulated by the elasto-viscoplastic model highly corresponding to the real behavior of the material. Also, the geometrically nonlinear behavior is taken into account using a total Lagrangian coordinate system, and the equilibrium equation of motion was numerically solved by a central difference scheme. A complete finite element program has been developed and the results obtained by it are compared with those in the references 1 and 2. The results are in good agreement with each other. As a case study of its application, the developed program was applied to a dynamic response analysis of a nuclear reinforced concrete containment structure. The results obtained from the' numerical examples are summarized as follows : 1. The dynamic magnification factor of the displacement and the stress were unrelated with the concrete strength. 2. As shown by the results that the displacement dynamic magnification factor were form 1.7 to 2.3 and the stress dynamic magnification factor from 1.8 to 2.5, the dynamic magnification factor of stress were larger than that of displacement. 3. The dynamic magnification factor of stress on the exterior surface was larger than that on the interior surface of the structure.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.148-157
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• 1999

Dynamic structural behavior in long span bridges, especially cable structures, is very sophisticated due to their flexibility and structural members are sequentially erected in each construction step. In this study, the consistent mass matrix for dynamic analysis is formulated and computational program considering construction sequences is developed where structural members can be builded or removed by command language and automatically reanalyzed in the moment when structural system is changed. The dynamic analysis, i.e. eigenvalue and time series analysis and the geometrically nonlinear analysis considering construction sequence are conducted to the Namhae Bridge. The analytical results are satisfactory compared with measuring values and the developed computational program can successfully be applied to design and safety check.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1394-1399
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• 2001

The purpose of this paper is that investigates the dynamic behavior characteristic of W.T.S(Wind Turbine System) and carries out the evaluation analysis during operating W.T.S. To investigate the dynamic behavior characteristic of W.T.S. the experiments to measure vibration of the blade from the attached accelerometer on the flap and edge section of the blade that is one of the most important elements of dynamic characteristic of W.T.S are performed. Natural frequency and mode shape are calculated with commercial program (STAR MODAL) using the measured vibration acceleration that receives the signal with F.F.T Analyzer from the accelerometer. For validation of these experiments. the finite element analysis is performed with commercial F.E.M Program (ANSYS) on the basis of the natural frequency and mode shape. The results indicate that experimental values have good agreements with the finite element analysis.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.505-509
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• 2005

Analysis program to estimate the dynamic characteristics of bridge is investigated by using three-dimensional analytical model considering vehicle-bridge interaction. A dynamic interaction models of the vehicle-bridge system are established, which is composed of a vehicle element model and a finite element bridge model. The vehicle models are established according to the structure and suspending properties of vehicle. The dynamic responses of the bridge are calculated. But the computer simulation program is being verified with field tests results, it must be corrected according to them.