• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.40-46
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• 2000

This study predicts the modified structural eigenvector and eigenvalue due to the change in the mass and stiffness of 2-dimesional continuous system by iterative calculation of the sensitivity coefficient using the original dynamic characteristic. The method is applied to examples of a crank shaft by modifing the mass and stiffness. The predicted dynamics characteristics are in good agreement with these from the structural analysis using the modified mass and stiffness. The predicted dynamic characteristics are in good agreement with these from the structural analysis using the modified mass and stiffness.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2590-2597
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• 2002

A new torque measuring apparatus adopting the basic principle of a capacitive type sensor is proposed in this article. Two plate electrodes are working as a capacitive sensor, whose capacitance varies as torque is applied. One end of each plate is connected to the torque carrying shaft. Output characteristics of the torque sensor were theoretically analyzed and its validity was investigated through experiment. Calculations and calibration experiments show that the output is nonlinear, that is, the sensitivity is very high at low torque but decreases as torque increases. The sensitivity of the proposed system is about 100 times roughly higher than that of a conventional 4-strain gauge type torque sensor.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.6
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• pp.105-111
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• 1995

The inverse dynamic equations for 5 link robot including a closed chain have been derived. The closed chain is virtually cut open, and the kinematics and dynamics of the virtual open chain robot are analyzed. The constraints are applied to the virtually cut joints by the Jacobian matrix which represents the configuration of the closed chain. The topology of tree structrued open chain robot is described by a FATHER array. The FATHER array of a link indicates the link tha tis connected in the direction of base link. Based on the inverse dynamic equations, the torque sensitivity models of the 5 link robot have been developed. The sensitivity models characterize the sensitivity of the driving torque with respect to the link parameters. All the procedures are illustrated through the 2 link robot.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1299-1307
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• 2014

In this work, an appropriate analysis model of a precise foot sensor with low detection pressure capability under a low range of variation in the dimensional variables was proposed. With a simple two-dimensional model, it was found that a remarkably high error level sometimes occurred between the analysis and experimental results. In order to overcome the error and improve the performance, a three-dimensional model was introduced, and the detection pressure and sensor characteristics were compared with those of the experimental results, which showed its enhanced performance with less error and higher precision.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.10a
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• pp.57-62
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• 1991

For the purpose of developing the method for efficiently calculating the design sensitivity and the reliability for the complicated structure such as ship structure, the probabilistic finite element method is introduced to formulate the deterministic design sensitivity analysis method and incorporated with the second moment reliability methods such as MVFOSM, AFOSM and SORM. Also, the probabilistic design sensitivity analysis needed in the reliability-based design is performed. The reliability analysis is carried out for the initial yielding failure, in which the derivative derived in the deterministic desin sensitivity is used. The present PFEM-based reliability method shows good agreement with Monte Carlo method in terms with the variance of response and the associated probability of failure even at the first or first few iteration steps. The probabilistic design sensitivity analysis evaluates explicitly the contribution of each random variable to probability of failure. Further, the reliability index variation can be easily predicted by the variation of the mean and the variance of the random variables.

• Journal of KSNVE
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• v.5 no.4
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• pp.555-563
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• 1995

This paper proposes the method of antiresonance frequency analysis of multi-input multi-output system. The structural dynamic modification techniques by antiresonance frequency analysis are also applied to reduce the undertest at specimen attachment points on the fixture in environmental vibration test, which is resulted from the inconsistency of antiresonance frequencies at any specified points. Several computer simulations show that the proposed method can remove the undertest problem which is not removed in conventional vibration test control. And the effectiveness of the method is verified with the impact hammer excitation of aluminium fixture model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.570-575
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• 2002

Servo performance of a disk drive is greatly affected by the mechanical resonance frequencies of the head gimbal assembly (HSA). It is important factor to allow broader bandwidths for servo system in improving overall drive performance. In this paper, an optimal design for ODD suspension is attempted to increase resonance frequencies in tracking direction. Initial model was designed and the design parameter was defined to the model. The mode frequency variation for the change of design parameter was observed by modal analysis using the finite element method(FEM). The sensitivity matrix was calculated from the observed data and so through sensitivity analysis, an optimized ODD suspension was designed to have the higher resonant frequency than the initial model.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.5
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• pp.93-99
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• 2000

In many dynamic structural optimization problems, the goal is to reduce the total weight of the structure without causing the resonance. Up to now, gradient informations(i.e., design sensitivity) have been used to achieve the goal. For some class of dynamic problems, especially coalescent eigenvalue Problems with multiobjective optimization, the design sensitivity analysis is too much complicated mathematically and numerically. Therefore, this article proposes a new technique fur structural dynamic modification using a mode modification method with Genetic Algorithm(GA). In GA formulation, fitness is defined based on penalty function approach. Design variables are iteratively improved by using genetic algorithm. Two numerical examples are shown, (ⅰ) a cantilevered plate, and (ⅱ) H-shaped structure. The results demonstrate that the proposed method is highly efficient.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.237-238
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• 2008

In this paper, the RCF method is applied to analyze small signal stability of power systems including thyristor controlled FACTS equipments such as TCSC. The eigenvalue sensitivity analysis algorithm in discrete systems by the RCF method are presented and applied to the power system including TCSC. The RCF analysis method enabled to precisely calculate eigenvalue sensitivity coefficients of dominant oscillation modes after periodic switching operations. These simulation results are very different from those of the conventional continuous system analysis method such as the state space equation method.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.602-603
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• 2007

In this paper, the RCF method is applied to analyze small signal stability of power systems including thyristor controlled FACTS equipments such as SVC. The eigenvalue sensitivity analysis algorithm in discrete systems by the RCF method are presented and applied to the power system including SVC. As a result of simulation, the RCF analysis method is very powerful to calculate the newly generated unstable oscillation modes precisely after periodic switching operations of SVC. Also the RCF analysis method enabled to precisely calculate eigenvalue sensitivity coefficients of dominant oscillation modes after periodic switching operations. These simulation results are very different from those of the conventional continuous system analysis method such as the state space equation method.