• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.4
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• pp.717-722
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• 2013

In this study, we investigated the design of a wire wedge bonding ultrasonic tool horn using finite element method (FEM) simulations. The proposed method is based on an initial design estimate obtained by FEM analysis. An ultrasonic excitation causes various vibrations of a transducer horn and capillary. A simulated ultrasonic transducer horn and resonator are then built and characterized experimentally using a laser interferometer and electrical impedance analyzer. The vibration characteristics and resonance frequencies close to the exciting frequency are identified using ANSYS. FEM analysis is developed to predict the resonance frequency of the ultrasonic horn and use it in the optimal design of an ultrasonic horn mode shape.

• 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.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.421-430
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• 2000

This paper describes an optimal design method which is applied a weighted least square (WLS) method for Magnetic Resonance Imaging (MRI) system. An optimal design approach is presented for a homogeneity superconducting magnet with the superconducting active shield especially for a magnetic resonance imaging system. The WLS is used to obtain the optimal configurations using the least amount and minimum volume of conductor, exhibiting the smallest level of field inhomogeneity and resulting in the least level of stray field. The proposed model is used to design a multiple-shield configuration for a 1.5 T MRI magnet. The field homogeneity is required less than 5 gauss stray field contour within 4m axially and 3m radially from origin. The designed magnet with the actively magnetic shielding coil out of main coils is analyzed by FEM and theoretical analysis method, investigated the field homogeneity.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.996-999
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• 2010

Aluminium extruded panel is the most important element for sound insulation in a express train. However, comparing with the flat plate with the same weight, the extruded panel shows remarkably low sound transmission loss above the 1st local resonance frequency, which is determined by the dimension of the core structure. Preceding study showed the possibility of the improvement of sound insulation performance by properly designing the core dimension. By the proper core design, local resonance frequency shifts to higher frequency region without any reduction of bending or torsional strength and without any weight increase. Based upon this result, this study investigates in detail the design modification of the core structure of the aluminium extruded panel used in a express train under development, in aspect of sound insulation. Design result is compared with those of other developed models.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.6
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• pp.729-737
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• 1998

In this paper, using $\mu$ synthesis algorithm with structured uncertainty, we design controller and apply it for the Two-Inertia resonance(TMS: Two Mass Spring) system. The TMS system is one of the simplest models which generate a torsional vibration. In this system, it is required to design a controller achieving the control performance while suppressing the torsional vibration. Furthermore, when vibration frequency for the system is varying by reason of parameter variations, we should consider parameter variations in controller design. Then, we design two other controller schemes of the PI controller and the standard $H_{\infty}$ controller and compare these controllers with the controller designed by the $\mu$ synthesis robust control method by using simulations and experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2019-2022
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• 2016

In the presence of an electrically conducting medical lead, radio frequency (RF) coils in magnetic resonance imaging (MRI) systems may concentrate the RF energy and cause tissue heating near the lead. A novel design for a medical lead to reduce this heating by introducing pins in the lead is presented. Peak 10 g specific absorption rate (SAR) in heart tissue, an indicator of heating, was calculated and compared for both conventional (Medtronic) lead design and our proposed design. Remcom XFdtd software was used to calculate the peak SAR distribution in a realistic model of the human body. The model contained a medical lead that was exposed to RF magnetic fields at 64 MHz (1.5 T), 128 MHz (3 T) and 300 MHz (7 T) using a model of an MR birdcage body coil. The proposed design of adding pins to the medical lead can significantly reduce the heating from different MRI systems.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.7-12
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• 2008

In the design of modem rotating machinery, it is often necessary to increase the performance of rotor-bearing system. Since a critical speed range influences the performance and safety of the whole system, it should be necessary to constrain the critical speed and thus resonance response in design process to result in large vibration. Consequently the minimization of resonance response amplitudes within the operation range of the rotor system becomes the most primary design objective. In this paper, based on the assumption that the external shape of rotating-shaft, bearing supporting positions and etc, the natural frequency analysis of spindle is performed by ANSYS $10.0^{(R)}$ Optimum design is conducted using the RBF model.

• Journal of KSNVE
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• v.8 no.2
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• pp.346-352
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• 1998

This paper presents actuating characteristics of an asymmetric high-speed optical pick-up fine actuator that can be installed in a small area such as a notebook personal computer. In the asymmetric actuator four points (mass center, actuation center, supporting point of wire suspension on a bobbin, and optical axis) are not coincident so that the proposed actuator suspension reveals undesirable suspension resonance in the pitch and yaw direction. Lumped parameter dynamic model in each direction is used to investigate the driving characteristics with respect to relative location of the four points. Some of desired design directions toward reducing resonance peaks are suggested by using sensitivity information. In order to avoid undesirable resonance, at least supporting point on the obbin must be located in the middle of the mass and actuation center of the asymmetric pick-up actuator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.638-641
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• 2002

This paper presents design and construct of flat type step-down piezoelectric transformer for the application to AC-adapters. This piezoelectric transformer operated in resonance vibration mode. In this paper, Finite element method(FEM) was used for analysis piezoelectric transformers. Vibration mode and electric field of piezoelectric transformer at resonance frequency were simulated. Using this simulation, we manufactured flat type piezoelecric transformer and measured its output characteristics. As results, output power was linearly increased by increasing input power at resonance frequency. And it was found that the transformer exhibited an output power of 11.4[W] at 60[V] input voltage. From these results, we expect that this piezoelecric transformer can be applied to AC adapters.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.97-100
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• 2005

Precise prediction of resonance frequency has been the subject of numerous papers related to Helmholtz resonator design because of its high performance at the frequency. The resonance frequency is dependent upon not only the internal dimensions of resonator but also the external boundary conditions such as the existence of other resonators in Helmholtz resonator array panel. However, the latter effect, which changes the external end correction of resonator, has not been well studied. We propose a formula to calculate the radiation impedance (or external end correction) of Helmhoitz resonator array panel. Any distance between adjacent resonators and any angle of Incidence can be allowed in the method. Numerical examples show how and how much the distance affects the resonance frequency of the panel. It is also found that the maximum absorption of the panel varies with the resonator arrangement.