• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.67-69
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• 1999

This study deals with the unbalance response of a rotor of Switched Reluctance Motor(SRM) due to unbalanced mass. The method to analyze SRM with rotor-bearing system is based on an extension of the well-known Transfer Matrix Method(TMM). Most of the calculation results present the natural frequencies as a function of the speed of rotation which yields critical speeds and response to unbalanced mass.

• Wind and Structures
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• v.17 no.1
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• pp.107-121
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• 2013

This paper presents an experimental investigation concerning the peak amplitudes of oscillation of a square prism due to Vortex-Induced-Vibrations (VIV) as a function of the mass damping parameter $m^*{\zeta}$(the so called Griffin--plot); $m^*$ and ${\zeta}$ being, respectively, the non-dimensional mass and the mechanical (structural) damping ratio. With this purpose in mind, an electromagnetic actuator has been employed to provide controlled damping. During the experiments the mass--damping parameter was in the range 0.15 < $m^*{\zeta}$ < 2.4. Experiments show that there is a value of $m^*{\zeta}$ below which VIV appears combined with galloping and the prism oscillation increases monotonically with the incoming flow velocity. For $m^*{\zeta}$ >0.3 the present experiments show a well-defined VIV phenomenon and, consequently, a Griffin-plot can be defined.

• International Journal of Railway
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• v.6 no.4
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• pp.155-159
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• 2013

The purpose of this study was to develop a theoretical model to analyze the vibration of finite railways forced by distributed moving loads. The vibration characteristics of compliantly supported beam utilizing compressional damping model were investigated through the Rayleigh-Ritz method. The distributed moving load was analyzed as the cross correlation function on railways. This allowed the use of statistical characteristics for simulation of the moving train wheels on the rail. The results showed there is a critical velocity inducing resonant vibration of the rail. The mass spring resonance from the rail fastening systems exhibited significant influence on the resulting vibration response. In particular, the effect of the viscoelastic core damping was investigated as an efficient method for minimizing rail vibration. The decrease of the averaged vibration and rolling noise generation by the damping core was maximized at the mass-stiffness-mass resonance frequency.

• Wind and Structures
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• v.16 no.4
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• pp.341-354
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• 2013

This paper presents an experimental investigation concerning the peak amplitudes of oscillation of a square prism due to Vortex-Induced-Vibrations (VIV) as a function of the mass damping parameter $m^*{\zeta}$ (the so called Griffin--plot); $m^*$ and ${\zeta}$ being, respectively, the non-dimensional mass and the mechanical (structural) damping ratio. With this purpose in mind, an electromagnetic actuator has been employed to provide controlled damping. During the experiments the mass--damping parameter was in the range 0.15 < $m^*{\zeta}$ < 2.4. Experiments show that there is a value of $m^*{\zeta}$ below which VIV appears combined with galloping and the prism oscillation increases monotonically with the incoming flow velocity. For $m^*{\zeta}$ >0.3 the present experiments show a well-defined VIV phenomenon and, consequently, a Griffin-plot can be defined.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.199-204
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• 2006

In this paper, we propose an adaptive control algorithm to improve the position accuracy and reduce the nonlinear friction effects for linear motion servo system. Especially, the considered system includes not only the variation of the mass of the mover but also the friction change by the normal force. To adapt to these problems, we designed the controller with the mass estimator and the compensator by observing the variation of normal force. Finally, the numerical simulation results are presented in order to show the effectiveness of the proposed method to improve the position accuracy compared to other control methods.

• Structural Engineering and Mechanics
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• v.68 no.1
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• pp.39-51
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• 2018

In this study, a frequency domain model updating method is presented using power spectral density (PSD) data. It uses the sensitivity of PSD function with respect to the unknown structural parameters through a decomposed form of transfer function. The stiffness parameters are captured with high accuracy through solving the sensitivity equations utilizing the least square approach. Using numerically noise polluted data, the model updating results of a truss model prove robustness of the method against measurement and mass modelling errors. Results prove the capabilities of the method for parameter estimation using highly noise polluted data of low ranges of excitation frequency.

• Journal of the Korea Furniture Society
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• v.24 no.4
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• pp.318-328
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• 2013

This study aimed to examine the theoretical consideration and concept of hybrid that could be applicable to wood product design, to analyze design trend according to the morphological transformation by means of combination of hybrid material and function, to understand the correlation between type of wood product and materials and to apply it to the domestic and overseas hybrid concept of wood product design study. A study of assembling output by empirical experiment to embed natural resources into acrylic resin in order to develop wood products was carried out. And an wood product was suggested that satisfied lighting and hanger function through a new wood product design development combined with hanger function and lighting function. Through such process, a new design paradigm was suggested to cope with the periodic trend and to induce mass production of designed product. Thus, this study set a new guideline for activating wood product design and attempted to meet the social demand of encouraging new value creation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.298-303
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• 2003

The eccentric rotor system has various problems by vibration of unbalance mass. Specially, it is difficult to analyze vibration problem for the drum washing machine due to correlation of transmission paths. We analyze the mechanical structure by multidimensional spectral density to identify the maximum vibration magnitude at the frequency domain. It estimates the coherence function of the signals to pass the transmission paths. In case of the drum washing machine, because the transmission paths are correlated partially it needs to determinate the priority ranking. And the correlated parts are eliminated using conditioned spectral density function. Finally the shielding effect method confirms the reasonability of the modeling.

• PNF and Movement
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• v.15 no.1
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• pp.13-25
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• 2017

Purpose: This study investigated the coordination and contribution of body segments during functioning. Methods: The relevant literature related to body segments and function were reviewed. Results: Efficient control of function is considered with regard to a participant's ability to perform a sequence of movements in body segments, which progresses from the head to the arm, trunk, pelvis, and leg segments. Each segment performs a specific role, which environment explorer using visual information for the head, reaching and grasping for the arms, a stabilizer for the trunk, and the distribution of COM in the pelvis and leg. Conclusion: During any of the movements, the momentum generated by the proximal segments is transferred to the adjacent distal segments in an appropriate sequence. In assessing function for clinical intervention strategies, the segment coordination, segment sequence, transfer of the center of body mass, asymmetrical ratio, muscle activity, and compensatory strategies should be considered.

• Tunnel and Underground Space
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• v.28 no.1
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• pp.59-71
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• 2018

Since the generalized Hoek-Brown (GHB) function predicts the strength of the jointed rock mass in a systematic manner by use of GSI index, it is widely used in rock engineering practices. In this study, a series of 2D elasto-plastic FE analysis, which adopts the GHB criterion as a yield function, was carried out to investigate the radial convergence characteristics of circular tunnel excavated in the GHB rock mass. The effect of the plastic potential function on the elasto-plastic displacement was also examined. In the analysis, the wide range of both the $K(={\sigma}_h/{\sigma}_v)$ and GSI values are considered. For each K value, the variation of the ratio of sidewall displacement to roof displacement was calculated with varying GSI values and the obtained displacement patterns were analysed. The calculation results show that the displacement ratio significantly depends not only on the K value but also on the range of GSI value. In particular, for lower range of GSI value, the displacement ratio pattern calculated in the elasto-plastic regime is opposite to that predicted by the elasticity theory. In addition, the variation of the radial displacement ratio with GSI value for different types of plastic potential function showed similar trend.