• 한국산업융합학회 논문집
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• 제8권4호
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• pp.205-212
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• 2005

This paper presents the application of system identification approaches for the load carrying capacity evaluation of composite PCI girder bridges based on the result of field test. For these problems, the moment of inertia of cross-sectional area and the natural frequency of bridge were used as structural parameters, the SAP2000 program for the structural analysis and the SLP method for the minimum error. As a result, it is found that the proposed algorithm for this study appears applicable to real structures with reasonable complexity. It is shown that the introduction of approximate quadratic equations is more realistic and timesaving than the common methods.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.753-756
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• 2002

In this study, it is attempted to obtain the optimum size of holes in 15 square plate models where a hole exists on every quadrant of a plate, and to get eigenvalues by performing free vibration analysis far each model. Moreover, the specimen is produced from optimized square plate and eigenvalue of each plate is measured through the shocking load. And then the result is compared with that of finite element analysis. For free vibration analysis of the square plate, the boundary condition of finite element analysis and experiment is assumed as both ends support. From the results of this study, it is known that more stable structures can be designed by changing the natural frequency which is dependent on the location of holes and further studies are considered to be necessary for the basic design information.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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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.

• 한국정밀공학회지
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• 제20권5호
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• pp.132-139
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• 2003

In this study, it is attempted to obtain the optimum size of holes in 15 square plate models where a hole exists on every quadrant of a plate, and to get eigenvalues by performing free vibration analysis for each model. Moreover, the specimen is produced from optimized square plate and eigenvalue of each plate is measured through the shocking load. And then the result is compared with that of finite element analysis. For free vibration analysis of the square plate, the boundary condition of finite element analysis and experiment is assumed as both ends clamped support. From the results of this study, it is known that more stable structures can be designed by changing the natural frequency which is dependent on the location of holes and further studies are considered to be necessary fur the basic design information.

• 전기학회논문지
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• 제58권3호
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• pp.509-515
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• 2009

When a squirrel cage induction motor is loaded, the magnetic noise can increase depending on the load current. It is due to the variation of air gap harmonic fluxes from the rotor current induced by loading. This unfavorable noise can be anticipated by analysing the radial force waves in the air gap, the mode shapes of them, and stator core natural frequencies at each mode. With the experimental tests with the different rotor slot numbers, the variation of magnetic noise depending on the load current is studied and the method to reduce the magnetic noise is suggested with the newly developed magnetic noise analysis program.

• 한국안전학회지
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• 제13권2호
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• pp.13-21
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• 1998

This is a study on the natural vibration characteristics of Vehicle frame. Nowadays, many trucks freight the over-load, do the car designers consider the over-load about 200% in the design. It's necessary to make the model of a vehicle and simulate it for the test of driving condition, durability and vibration behavior before the vehicle is manufactured. If it is possible to make a simulation using the static and dynamic analysis, this is very useful in accomplishing an optimal design of the vehicle. In this paper, we studied the vibration characteristics of a truck body frame. The automobile body frame model for experiment is made smaller than real size frame with the ratio of 1/10. The vibration characteristics of a frame is considered as one of main factors in analyzing and improving the problem for ride comfort, noise and vibration reduction. Therefore, we experimented two method to neglect the nonlinearity. First is bolting and second is welding at the joint section. We compared computer simulation results and experimental data.

• 설비공학논문집
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• 제5권2호
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• pp.102-110
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• 1993

An isothermal analysis was conducted to develop the design tool of an aquifer thermal energy storage system. Taejeon aquifer was chosen for the analysis, and the variation of FRE(Fluid Recovery Efficiency) with respect to the aquifer natural velocity and thermal load were investigated. The analysis results were compared with those of ATESSS(Aquifer Thermal Energy Storage System Simulator) and agreed within 2% of discrepancy. It is recommended, based on the result of this study, that the system may be suitable for a large volume of hot or chill thermal energy storage system, such as for district heating or cooling.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권2호
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• pp.137-152
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• 2016

This paper studied the dynamic response of a new gasbag-type floating bridge under the effect of a moving load. The arbitrary Lagrangian-Eulerian (ALE) method was used to simulate the movement of seawater and air, and the penalty-based method was used to study the coupling between gasbags and fluid. A three-dimensional finite element model of the floating bridge was established, and the numerical model was verified by comparing with the experimental results. In order to prevent resonance, the natural frequencies and flexural mode shapes were analyzed. Based on the initial state analysis, the dynamic responses of the floating bridge subjected to different moving loads were investigated. Vertical displacements and radial deformations of gasbags under different loads were compared, and principal stress distributions of gasbags were researched while driving. The hinge forces between adjacent modules were calculated to ensure the connection strength. Besides, the floating bridge under wave impacting was analyzed. Those results can provide references for the analysis and design of this new floating bridge.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.110-118
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• 2008

This thesis introduces a study conducted by ANSYS, Finite Element Analysis program, on dynamic behavior by thickness of a chord and a brace of a jacket typed marine structure. As load condition to work on offshore structures is getting much more various, it becomes more important to design the structures and operate them. In addition, stability is also required. As the result of this study, it was proved that wind and wave load gives more affection on frequency than on added mass in the Modal Analysis. Also, the chord and brace affect stiffness more than diagonal brace according to sensitivity analysis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.247-250
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• 2000

This paper presents the dynamic analysis and experiment for a shaft system supported by angular contact ball bearings. Among others, the dynamic characteristics of bearings are significantly affected by axial preload and radial load applied. This paper rigorously analyzes the dynamic characteristics of a shaft system with angular contact ball bearings subject of axial preload so as to result in eigenvalues as well as bearing stiffness characteristics. Experiments are also performed to identify natural frequencies and stiffness characteristics of bearings implemented. Comparison is made on the theoretical and experimental results.