• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.50-54
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• 2004

A numerical system to extract effective elastic properties of polycrystalline thin-films for MEMS devices is already developed. In this system, the statistical model based on lattice system is used for modeling the microstructure evolution simulation and the key kinetics parameters of given micrograph, grain distributions and deposition process can be extracted by inverse method proposed in the system. In this work, the effects of kinetics parameters on the extraction of effective elastic properties of polycrystalline thin-films are studied by using statistical method. The effects of the fraction of the potential site( $f_{P}$ ) and the nucleation probability( $P_{N}$ ) among the parameters for deposition process of microstructure on the extraction of effective elastic properties of polycrystalline thin-films are studied.d.d.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.562-564
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• 1994

IGBT devices have the best features of both power MOSFETs and power bipolar transistors, i. e., efficient voltage gate drive requirements and high current density capability. The interaction of the IGBT with the load circuit can be described using the device model and the state equation of the load circuit. The protection circuit requirements are unique for the IGBT and can be examined using the model.

• Transactions of Materials Processing
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• v.13 no.3
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• pp.230-235
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• 2004

A new design based on the appropriate geometry of molded part and type of runner system under the optimal processing conditions was proposed to minimize the micro weld lines on the sub deco surface molded by two shot molding. Theoretical and experimental studies were conducted to examine the cause of the weld lines during the overmolding process in two shot molding. Various dimensions and geometries of substrate$(1^{st}shot)$ and the wall thickness of overmold$(2^{nd}shot)$ have been proposed to avoid the weld lines which are the most inevitable appearance defects occurred on the sub deco. The each design proposal was analyzed by mold flow analysis after part modeling. The analysis results were compared with molded part from mass production tool. It could be seen that from the analysis that the proper geometry of plastic part and type of runner system considering pressure drop under the optimal processing conditions were the most influential factors to avoid weld lines occured on the sub deco.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.1
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• pp.83-90
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• 2000

The purpose of this study is the development of CAM system which can machine and measure any shape by CNC lathe. The overall goal of the CAM system is to achieve the CNC lathe machining, from roughing through to final measuring, The hardware of the system comprises PC, CNC lathe and measuring tools. There are three steps in the CNC lathe machining and measuring, (1) geometric modeling by the shape patterns, (2) NC commands generation by the tool path compensated for tool nose radius, (3) machining and workpiece measuring on the lathe. It is developed a software package, with which we can conduct a micro CAM system in the PC without economical burden.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.4
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• pp.253-258
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• 2002

This paper reports the design, modeling, fabrication and measurement of passive microvalves, which are applicable to glaucoma implants. The proposed microvalves were designed using fluidic theory. The microvalves consisted of microchannels and chambers. The microchannels had a constant fluidic resistance generating a pressure difference. Six kinds of microvalves were designed using fluidic equations for laminar flow and fabricated to examine the influences of chamber size, channel length and the shape of channel cross section. The pressure difference between the designed microvalve and the fabricated microvalve was measured to be less than 4%.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.4
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• pp.288-294
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• 2002

This paper presents the design, fabrication and characterization of a 32 by 32 electroplated micromirror array on a glass, a low cost substrate. Approaches taken in this work for the fabrication of micromachined mirror arrays include a line addressing scheme, a seamless array design for high fill factor, planarization techniques of polymeric interlayers, a high yield methodology for the removal of sacrificial polymeric interlayers, and low temperature and chemically safe fabrication techniques. The micromirror is fabricated by aluminum and the size of a single micromirror is 200 $\mu\textrm{m}{\;}{\times}200{\;}\mu\textrm{m}$. Static deflection test of the micro-mirror has been carried out and pull-in voltage of 44V and releasing voltage of 30V was found.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.34-36
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• 1989

Since the linear step motor(LSM) has the merits which can be controlled the position and velocity by using the micro-computer and has no mechanical transducer such as belt and gear, it's usefullness has been fitted for the printer, x-y plotter, OA machinery and so on. In designing the LSM, we are faced up to the calculation of forces. in this paper, the permeance modeling method suited for the design of transverse flux type linear step motor(TFM) is presented and simulated.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.105.5-105
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• 2002

Digital Polymer Motor (DPM) based on dielectric elastomer is presented. It includes all the supplementary parts for actuation such as micro-controller, DC-DC converter etc. DPM can be operated by itself with the program embedded and controlled via serial interface with PC. The actuator accomplishes bidirectional actuation and compliance controllability, which are important characteristics for a biomimetic artificial muscle actuator. DPM accomplish these requirements without any mechanical substitute or complicated algorithms. Its basic concepts and working principles are addressed with modeling and simulation and the compliance controllability are verified by conducting several experiments. $\textbullet$ Polymer, Dielectric, Biomimetic

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.19-22
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• 2004

A numerical system to extract effective elastic properties of polycrystalline thin-films for MEMS devices is already developed. In this system, the statistical model based on lattice system is used for modeling the microstructure evolution simulation and the key kinetics parameters of given micrograph, grain distributions and deposition process can be extracted by inverse method proposed in the system. In this work, the effective elastic properties of polysilicon, $BaTiO_3\;and\;ZrTiO_4$ are extracted using this system and by employing the fraction of the potential site($f_P$) as a kinetics parameter for the microstructure evolution, the statistical tendency of these materials is studied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1697-1704
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• 2001

A finite element model for polarization switching in electro-mechanically coupled materials is proposed and applied to predict the switching behavior of a two-dimensional ferroelectric ceramic. A complicated micro-structure existing in the material is modeled as il continuum body and a simple 3 node triangle finite element with nodal displacement and voltage degrees of freedom is used for a finite element analysis. The elements use nonlinear constitutive equations, switching criterion and kinetic relation, fur representation of material response at strong electric and stress fields. The polarization state of the material is represented by internal variables in each element, which are updated at each simulation step based on the proposed constitutive equations. The model reproduces strain and electric displacement hysteresis loops observed in the material.