• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.220-225
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• 2003

Recent issue of optical actuator is applying to mobile device. It leads actuator to become smaller than conventional type. This paper proposes the design of micro actuator plate spring and analysis of its vibration characteristic. Considering natural frequency of spindle motor, 1st and 2nd eigenfrequency of micro actuator must avoid its natural frequency. First, magnetic circuit is designed by using fine pattern coil and magnetic force is acquired by simulation program. Then, concept design is achieved by topology optimization. From concept design, micro actuator plate spring is embodied through DOE(design of experiment). Finally, considering vibration characteristic simultaneously, optimal plate spring design is determined by RSM(response surface method).

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.5
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• pp.456-464
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• 2014

Commercial vehicle drivers typically feel more fatigued compared to general-public drivers. because they spend longer periods of time driving and experience more rough road conditions. This study showed that the application of a magnet, a linear spring, and a seat suspension with nonlinear characteristics was the optimal design to increase comfort while driving. The resonant frequency for the optimal design suspension was 2.8 Hz, and the stiffness was analyzed through displacement-load experiments. Vibration transmissibility was analyzed by suspension stiffness and the existing dynamic compression. The magnetic spring type was at 0.875. As a result, the X-type magnetic spring performed better than the existing spring at 0.729.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.353-360
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• 2015

Commercial drivers feel tired more than the general public, because their driving times are long and they experience more idle vibration. In this study, we developed a nonlinear model of a magnetic, linear spring seat suspension to determine the optimal design to improve ride comfort. The resonant frequency for the optimal design of the suspension was found to be 3.5 Hz, and the stiffness was analyzed through displacement-load experiments. Additionally, the vibration transmissibility was analyzed by the suspension stiffness, and the existing coil spring type vibration transmissibility was found to be 0.99. A parallelogram type magnetic spring was determined to result in a better performance than the existing spring with a vibration transmissibility of 0.823.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.819-824
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• 2012

This paper presents the wideband vibration system of an electromagnetic vibration energy harvester that obtained electric power for wireless sensor applications from the ever-change vibrations of bridge. It is a system with two degree of freedom vibrations that are composed of two mass and two spring respectively. One system is housing mass and spring, the other is the magnetic mass and spring that is the vibration system construction's element of electromagnetic vibration energy harvester. In other words, it is called dynamic vibration absorber. This paper show that the ratio of housing mass to magnetic mass decides the bandwidth and the size of amplitude of magnetic mass in electromagnetic vibration energy harvester. Therefore, it is necessary to improve the efficiency of energy in electromagnetic vibration energy harvester for wireless sensor applications.

• Transactions on Electrical and Electronic Materials
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• v.13 no.3
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• pp.125-128
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• 2012

This paper describes the design, simulation and characterization of an AA size electromagnetic energy harvester that is capable of converting environmental vibration into electrical energy. A magnetic spring technique is used to scavenge energy from low frequency external vibrations. The generator is characterized by ANSYS 2D finite element analysis, and optimized in terms of moving mass, fixed magnet size, coil width and load resistance. The optimized energy harvester is able to generate 53.5 mW of average power at 8.1 Hz resonance frequency, with a displacement of 0.5 mm.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.98-103
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• 1998

Recently, DVD/CD compatible driver is needed for DVD and CD is widely used as a new optical data restoring device. The optical systems of DVD and CD driver are different because they have different optical feature. If only one objective lens is used, the change of an aperture or a dual focal length of the lens is required. This method, however, increases the number of parts and results in loss of the power of laser light. Hence, we propose a dual lens actuator design that can read DVD and CD respectively. Albeit magnetic spring is important mechanism in the dual lens actuator design, there has not been the systematic approach to design the mechanism in the preceding researches. In this article. the guideway to design magnetic spring is presented by using the qualitative theoretical approach and the finite element analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1942-1949
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• 2004

SLA(Scanned Linear Array) is a portable display unit for implementing next-generation virtual realities, utilizes a design that light generated by a line of LEDs is reflected from the rapidly oscillating mirror to generate a raster display. Reaction forces generated by the motions of the mirror and counter-balance mass cancel each other at the device base, reducing vibration. Metal leaf springs have been extensively applied in such portable units. Magnetic springs have been developed and adopted that can replace the metal spring and can avoid many disadvantages of metal springs. We model and analyze the dynamics of the structure with magnetic springs and present the simulation and experimental analysis results, which can be utilized for identifying and eliminating possible problem sources in removing shaking forces and moments, and oscillating the mirror at the required amplitude and frequency. Finally, we present the improved novel magnetic actuator model which can be applied in portable display units.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1128-1138
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• 2010

One of the typical problems in the precise vibration is resonance characteristics at low frequency disturbance due to a heavy mass. An electro-magnetic(EM) air spring is a kind of vibration control unit and active isolator. The EM air spring in this study aims at removing the low frequency resonance for semiconductor manufacturing. The mechanical and electronic parts in the active isolator are designed to operate under a weight of 2.5 tons. The EM spring is floated using air pressure in a pneumatic elastic chamber and actuated by EM levitation force. The actuator consists of a EM coil and a permanent magnetic plate which are installed inside of the chamber. An air mount was constructed for the experiment with a stone surface plate, 4 active air springs, 4 gap sensors, a DSP controller, and a multi-channel power amp. A PD control method and operating logic was applied to the DSP. Simulation using 1/4 model was carried out and compared with the experiments. The time duration and maximum peak at resonance frequency can be reduced sharply by the proposed system. The results show that the active system can avoid the resonance caused by the natural frequency of the passive system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1246-1253
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• 2007

The recent issue of optical pickup actuators is to apply optical storage devices to mobile devices such as a cellular phone and PDA. It requires actuators to become smaller than conventional types. As the size becomes smaller, the magnetic force is reduced and the assembly of optical pickup actuators becomes more difficult. In addition, its dynamic characteristics are changed. In this paper, methods to improve magnetic forces and dynamic characteristics are suggested and the optimal result of the plate spring design is obtained. A diamond shape magnet and the fine pattern coil (FPC) are used to improve magnetic forces and damping elements are attached to decrease the peak magnitude of the mode instead of using structural damping, mostly for the purpose of improving the accuracy of the finite element simulation. To get more stable dynamic characteristics than conventional ones, a plate spring is applied to the optical pickup actuator and it is optimized with topology and parameter optimization to obtain the concept and the detail design, respectively.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.85-89
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• 2007

Linear ball guideways have been used recently in precision or ultra-precision positioning devices. However, when the inner balls begin to roll or the moving direction reverses, these guideways are subject to rolling friction or nonlinear spring behavior. An ultra-precision device with a linear motor, referred to as a 'tunnel actuator' (TA), has been constructed to measure these phenomena. The application of a TA is beneficial for two reasons: it mostly cancels the attractive magnetic force between the stator and mover (armature), and its magnetic flux leakage is very low. The influence of the nonlinear spring behavior in ball guideways was investigated in this study using the pure driving force from a TA. The equilibrium between the driving force from the TA and the nonlinear spring force provided great accuracy for a positioning stage using a linear ball guideway.