• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.4
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• pp.730-734
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• 2013

The dynamic simulation of machine tools and motion control systems has been widely used for optimization, design verification, control design, etc. There are three main streams in dynamic simulation: structural dynamic analysis based onthe finite element method, dynamic motion analysis based on equations of motion, and control system analysis based on transfer functions. Generally, one of these dynamic simulation methods is chosen and employed for specific purposes. In this study, an integrated dynamic simulation is introduced, in which the structure, motion, and control dynamics are combined together. Commercially well-known software is used in the integrated dynamic simulation: ANSYS, ADAMS, and Matlab/Simulink. Using the integrated dynamic simulation, the dynamics of a magnetic bearing stage is analyzed and the causes of oscillation and noise are identified. A controller design for suppressing a flexible dynamic mode is carried out and verified through the integrated dynamic simulation.

• Earthquakes and Structures
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• v.15 no.2
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• pp.155-164
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• 2018

Design of structures subjected to blast loads are usually carried out through nonlinear inelastic dynamic analysis followed by imposing acceptance criteria specified in design codes. In addition to comprehensive aspects of inelastic dynamic analyses, particularly in analysis and design of structures subjected to transient loads, they inherently suffer from convergence and computational cost problems. In this research, a strategy is proposed for design of steel moment resisting frames under far range blast loads. This strategy is inspired from performance based seismic design concepts, which is here developed to blast design. For this purpose, an algorithm is presented to calculate the capacity modification factors of frame members in order to simplify design of these structures subjected to blast loading. The present method provides a simplified design procedure in which the linear dynamic analysis is preformed, instead of the time-consuming nonlinear dynamic analysis. Nonlinear and linear analyses are accomplished in order to establish this design procedure, and consequently the final design procedure is proposed as a strategy requiring only linear structural analysis, while acceptance criteria of nonlinear analysis is implicitly satisfied.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.5
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• pp.389-404
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• 2017

The main purpose of this presented investigation is to build up the BHMS based on GNSS. This proposed monitoring system can conduct the deflection and dynamic characteristics analysis by using only GNSS positioning solution. The general bridge monitoring system being operated recently is composed of a combination of various sensors that are able to conduct deflection monitoring and dynamic characteristics monitoring analysis at the same time. However, GNSS based BHMS has the unique procedure in terms of data analysis. In the other words, GNSS positioning solution is firstly applied to deflection monitoring analysis then, this deflection analysis can be sequentially reflected in the dynamic characteristics. Unfortunately, the adjustment result of GNSS positioning solution estimated through various options and conditions and the process of monitoring analysis has not been fulfilled systematically. This means that different results or analysis value are presented according to the methodology and officers. Most of researches have been focusing on deflection monitoring analysis and some investigation regarding to dynamic characteristics is recently introduced. Moreover, it is not still reported the systematic investigation with regards to proper filtering and analysis methodology. This study was carried out based on a large amount of data, from this, various variables not reported yet are actively considered. Therefore, specific software for both monitoring analysis have been developed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.844-848
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• 2004

We evaluate the durability of vehicle chassis component under dynamic loadings. Since the fatigue analysis of vehicle component is based on the dynamic load history it must be done by dynamic analysis. But in case the vehicle component has natural frequencies much larger than reversing frequencies of load history, we can get small analysis errors by applying quasi-static analysis. So it is inefficient that we apply to the dynamic analysis for all the vehicle components. In this research, we discuss the quasi-static analysis method which is appropriate for the fatigue analysis. And in case we can only perform the fatigue analysis based on dynamic analysis, we introduce more efficient method in the analysis time and hard disk storage.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1109-1114
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• 2022

The SMART (System-integrated Modular Advanced ReacTor) is an integral-type small modular reactor developed by KAERI (Korea Atomic Energy Research Institute). This paper discusses the feasibility and applicability of a 3D-based equivalent model using dynamic condensation method for seismic analysis of a SMART control rod drive mechanism. The equivalent model is utilized for complicated seismic analysis during the design of the SMART. While the 1D-based beam-mass equivalent model is widely used in the nuclear industry for its calculation efficiency, the 3D-based equivalent model is suggested for the seismic analysis of SMART to enhance the analysis accuracy of the 1D-based equivalent model while maintaining its analysis efficiency. To verify the suggested model, acceleration response spectra from seismic analysis based on the 3D-based equivalent model are compared to those from the 1D-based beam-mass equivalent model and experiments. The accuracy and efficiency of the dynamic condensation method are investigated by comparison to analysis results based on the conventional modeling methodology used for seismic analysis.

• Tribology and Lubricants
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• v.39 no.2
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• pp.35-42
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• 2023

Bearing is a mechanical component that supports loads and transmits rotation. As the application of high-value-added products such as semiconductors, aviation, and robots have recently become diverse and more precise, an accurate bearing performance prediction and evaluation technology is required. Bearing performance evaluation can be divided into evaluations based on bearing theory and on numerical analysis. An evaluation based on numerical analysis is a technique that has been highlighted because the problems that remained unsolved owing to time problems can be solved through recent developments in computers. However, current studies have the disadvantage of not considering the essential changes over time and bearing rotation. In this study, bearing performance evaluation based on rigid body dynamic analysis considering rotation and load over time is performed. Rigid body dynamic analysis is performed for deep groove ball bearing to calculate the load applied by the ball. The reliability of the analysis is verified by comparing it with the results calculated using bearing theory. In addition, rigid body dynamic analysis is performed for automotive wheel bearings to calculate the contact angle and load applied by the ball for cases where axial load and radial load are applied, respectively. The effect of rotation and load over time is evaluated from these results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.898-901
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• 2004

Generally, in case the natural frequency of vehicle components is larger than the reversing frequency of load history, we can obtain the analysis results with small errors. But in case of having the low natural frequency, we must avoidably carry out the dynamic analysis, and it requires much time and storage. Specially executing the fatigue analysis for vehicle components requires more time. To this end, it is not easy that we accomplish the optimization considering fatigue for the vehicle component based on the dynamic analysis. In this research we introduce an efficient method which performs the fatigue analysis based on the dynamic analysis. Finally as making the response surface we optimize the vehicle component under dynamic fatigue.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1949-1957
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• 2000

All the loads in the real world act dynamically on structures. Since dynamic loads are extremely difficult to handle in analysis and design, static loads are utilized with dynamic factors. The dyna mic factors are generally determined based on experiences. Therefore, the static loads can cause problems in precise analysis and design. An analytical method based on modal analysis has been proposed for the transformation of dynamic loads into equivalent static load sets. Equivalent static load sets are calculated to generate an identical displacement field in a structure with that from dynamic loads at a certain time. The process is derived and evaluated mathematically. The method is verified through numerical tests. Various characteristics are identified to match the dynamic and the static behaviors. For example, the opposite direction of a dynamic load should be considered due to the vibration response. A dynamic bad is transformed to multiple equivalent static loads according to the number of the critical times. The places of the equivalent static load can be different from those of the dynamic load. An optimization method is defined to use the equivalent static loads. The developed optimization process has the same effect as the dynamic optimization which uses the dynamic loads directly. Standard examples are solved and the results are discussed

• International Journal of Highway Engineering
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• v.19 no.1
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• pp.73-80
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• 2017

PURPOSES : This paper presents a comparison study between dynamic and static analyses of falling weight deflectometer (FWD) testing, which is a test used for evaluating layered material stiffness. METHODS: In this study, a forward model, based on nonlinear subgrade models, was developed via finite element analysis using ABAQUS. The subgrade material coefficients from granular and fine-grained soils were used to represent strong and weak subgrade stiffnesses, respectively. Furthermore, the nonlinearity in the analysis of multi-load FWD deflection measured from intact PCC slab was investigated using the deflection data obtained in this study. This pavement has a 14-inch-thick PCC slab over fine-grained soil. RESULTS: From case studies related to the nonlinearity of FWD analysis measured from intact PCC slab, a nonlinear subgrade model-based comparison study between the static and dynamic analyses of nondestructive FWD tests was shown to be effectively performed; this was achieved by investigating the primary difference in pavement responses between the static and dynamic analyses as based on the nonlinearity of soil model as well as the multi-load FWD deflection. CONCLUSIONS : In conclusion, a comparison between dynamic and static FEM analyses was conducted, as based on the FEM analysis performed on various pavement structures, in order to investigate the significance of the differences in pavement responses between the static and dynamic analyses.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1195-1201
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• 2002

Researches on the FRF-based substructuring method have been mainly focused on vibratory response analysis. Present study Is concerned about the application of the method to the dynamic stress analysis of a air-conditioner compressor mounting bracket in a passenger car. This is performed by using reaction forces that can be obtained by the FRF-based substructuring method. The air-conditioner system, composed of a compressor and bracket, Is analyzed by using the FRF-based substructuring method. The experimental and numerical FRFs are combined to calculate the system responses and reaction forces at the connection point. The dynamic reaction forces plugged into the bracket FE model to compute the stresses of the bracket Dynamic strains by the present method are compared with those from strain-gage test for bracket system on shaker. The comparison shows possibility of practical usage of the method for the real problem