• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.234-241
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• 2002

An optical pickup actuator is an objective-lens-moving mechanism that provides a means to follow the disk displacement accurately(1). In this paper, a slim type optical pickup actuator for Notebook PCs is analyzed and designed to improve the driving sensitivity A three dimensional equivalent magnetic circuit network method (3D-EMCN method) is proposed for an analysis method which provides better characteristics in both precision and computation time of analysis comparing with a commercial three-dimensional finite element (3D-FEM) codes. To verify the validity of proposed method, we made a comparison between the analysis results and the experimental ones. We also compared this analysis results with 3D-FEM results. Among the several optimal algorithm, we adopt a niching genetic algorithm, which renders a set of the multiple optimal solutions. RCS (Restricted Competition Selection) niching genetic algorithm is used for optimal design of the actuator's performance. Recently, the pickup actuator needs additional driving structure for radial and tangential tilting motion to obtain better pick-up performance. So we applied the proposed method to the model containing tilting coils.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.2
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• pp.115-119
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• 2016

Winding is one of the major processes in roll-to-roll systems. Taper tension profile in a winding determines the distribution of stress in the radial direction, i.e., the radial stress in the wound rolls. Maximum radial stress is major cause of material defect, and this study has been actively proceeded. Traditional models of radial stress model were focused on flexible and light substrate. In this study, we developed an advanced radial stress model including effects of both these parameters(weight and stiffness) on the radial stress. The accuracy of the developed model was verified through FEM(Finite Element Method) analysis. FEM result of maximum radial stress value corresponds to 99 % in comparison to result with the model. From this study, the material defects does not occur when the steel winding. And steel industry can be applied to improve the winding process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.2
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• pp.147-151
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• 2011

We were analyzed the piezoelectric characteristic for electronics printing to inkjet printing system. These applications were possible use to Actuator, MEMS, FPCB, RFID, Solar cell and LCD color filter etc. Piezoelectric print head is firing from ink droplet control consideration ink viscosity properties. At this time, micro pattern for PCB metal printing was possible by droplet control of piezoelectric driving. These driving characteristics are variable voltage pulse waveform. We are used the piezoelectric analysis software of Finite Element Method (FEM), Piezoelectric design parameters are acquired from piezoelectric analysis, and measurement of piezoelectric. It designed for piezoelectric head to possible electric print pattern of inkjet printing system. For this validity we were established through in comparison with simulation and measurement. Designed piezoelectric specification obtained voltage 98V, firing frequency 10 kHz, resolution 360dpi, drop volume 20pl, nozzle number 256, and nozzle pitch 0.33 mm.

• Structural Engineering and Mechanics
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• v.48 no.5
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• pp.697-709
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• 2013

A simulation method called modified differential transform is studied to solve the free vibration problems of uniform Euler-Bernoulli beam. First of all, the modified differential transform method is derived. Secondly, the modified differential transformation is applied to uniform Euler-Bernoulli beam free-free vibration. And then a set of differential equations are established. Through algebraic operations on these equations, we can get any natural frequency and normalized mode shape. Thirdly, the FEM is applied to obtain the numerical solutions. Finally, mode experimental method (MEM) is conducted to obtain experimental data for analysis by signal processing with LMS Test.lab Vibration testing and analysis system. Experimental data and simulation results are illustrated to be in comparison with the analytical solutions. The results show that the modified differential transform method can achieve good results in predicting the solution of such problems.

• Smart Structures and Systems
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• v.15 no.4
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• pp.1019-1039
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• 2015

Shanghai Tower is a composite structure building with a height of 632 m. In order to verify the structural properties and behaviors in construction and operation, a structural health monitoring project was conducted by Tongji University. The monitoring system includes sensor system, data acquisition system and a monitoring software system. Focusing on the health monitoring in construction, this paper introduced the monitoring parameters in construction, the data acquisition strategy and an integration structural health monitoring (SHM) software. The integration software - Structural Monitoring/ Analysis/ Evaluation System (SMAE) is designed based on integration and modular design idea, which includes on-line data acquisition, finite elements and dynamic property analysis functions. With the integration and modular design idea, this SHM system can realize the data exchange and results comparison from on-site monitoring and FEM effectively. The analysis of the monitoring data collected during the process of construction shows that the system works stably, realize data acquirement and analysis effectively, and also provides measured basis for understanding the structural state of the construction. Meanwhile, references are provided for the future automates construction monitoring and implementation of high-rise building structures.

• Steel and Composite Structures
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• v.13 no.5
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• pp.409-421
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• 2012

Recently, as the height of building is getting higher, the applications of CFST column for high-rise buildings have been increased. In structural system of high-rise building, The RC core and exterior concrete-filled tubular (CFST) column-beam pinned connection is one of the structural systems that support lateral load. If this structural system is used, due to the minimal CFST column thickness compared to that of the CFST column width, the local moment occurred by the eccentric distance between the column flange surface from shear bolts joints degrades the shear strength of the CFST column-beam pinned connections. This study performed a finite element analysis to investigate the shear strength under eccentric moment of the CFST column-beam pinned connections. The column's width and thickness were used as variables for the analysis. To guarantee the reliability of the finite element analysis, an actual-size specimens were fabricated and tested. The yield line theory was used to formulate an shear strength formula for the CFT column-beam pinned connection. the shear strength formula was suggested through comparison on the results of FEM analysis, test and yield lime theory, the shear strength formula was suggested.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.1
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• pp.29-35
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• 2015

In this study, a FEM analysis is undertaken of a rubber sleeve which is mounted onto a spreading mandrel so as to avoid marking the first wrappings of coils (known as the 'end-mark'), as occasionally occurs when a concentrated load is placed on the edge of a steel sheet, significantly reducing its quality. A commercial numerical package, ANSYS, was utilized to analyze the structural behavior of the rubber sleeve. In general, the strain of the sleeve increases as the thickness of the rubber layer (H) covering the tubes increases, thus also increasing the surface of the sleeve for a constant boundary condition, and decreasing the pitch (P) between each tube, resulting in an increase in the strain on the surface of the sleeve for all rubber thickness conditions tested here. In a comparison of two different materials, rubber and urethane, when H=3 mm and P=1.1D, the maximum total deformations in these cases are 0.12669 mm and 0.086623 mm, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.482-492
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• 2004

Recently. the market trend for marine diesel engine has involved the lower running speeds. larger stroke/bore ratio and higher combustion pressure. Consequently, because of the flexible engine shafting system due to the larger mass. inertia and the more elasticity, the complicated coupled torsional-axial vibrations have occurred in the operating speed range. Also, the vibrations act as an excitation on the hull-structural vibration. To predict the vibration behavior with more accuracy and reliability. many studies have proposed the several kinds of method to calculate the stiffness matrix of crankshaft. However, most of these methods have a weak point to spend much time on three dimensional modeling and meshing work for crankshaft. Therefore. in this work. the stiffness matrix for the crankthrow is calculated using the energy method (Influence Coefficient Method, ICM) with the each mass having 6 degree of freedom. Its effectiveness is verified through the comparison with the stiffness matrix obtained by using the finite element method (FEM) and measured results for actual ships propulsion system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.4
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• pp.378-385
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• 2009

In establishing silent environment such as automobile and industrial instrument, the roles of the insulating materials are critical. The proper and effective positioning of insulating materials is essential in the field of noise as well as in designing silent automobile. In this paper, we proposed the systematic and efficient scheme for optimizing complete automotive interiors for noise control. In order to attain this purpose, following analysis has been carried out: First, measuring the Biot parameters of insulating materials and the transmission loss with reflecting the appropriate arrangement of insulating materials has been experimented. In addition, we made comparison among transmission loss by the tools of analysis and verification, experimental value under consideration of various situations of automobile and analysis by the SEA.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.3
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• pp.47-52
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• 1999

Fatigue test is an essential procedure in the dynamic structure design. It is performed to confirm that the structure should safety the required life. In this study, fatigue life for 750㎾ class horizontal axis wind turbine composite blade was investigated. Required fatigue stress was calculated by fan Bond's empirical equation and S-N linear damage method. Fatigue load for FEM analysis was calculated using load spectrum through experiments and Spera's method. Service fatigue stress was obtained by FEM with the calculated fatigue load. From comparison of the fatigue stresses, fatigue life over 20 years was confirmed.