• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.3
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• pp.182-188
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• 2001

A solenoid-type MEMS inductor with a quality factor over 10 at 2 GHz has been developed using an electroplating technique. The integrated spiral inductor has a low Q factor due to substrate loss and skin effects. It also occupies a large area compared to the solenoid-type inductor. The direction of flux of the solenoid-type inductor is parallel to the substrate, which can lower the substrate loss and other interference with integrated passive components. To estimate the characteristics of the proposed inductor over a high frequency range, the 3D FEM (Finite Element Method) simulation is used by using the HFSS at the Ansoft corporation. The electroplated solenoid-type inductor is fabricated on a glass substrate step by step by using photolithography and copper electroplating. The fabrication process to improve the quality factor of the inductor is also developed. The achieved inductance varies within a range from 0.5 nH to 2.8 nH, and the maximum Q factor is over 10.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1357-1365
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• 2002

A robot hand is used to transport the glass substrate in TFT-LCD manufacturing process. Carbon/epoxy composite is one of the best materials for this kind of robot hand application, due to their lightweight, high stiffness, and good damping characteristics. Major requirement of the robot hand is given as allowable deflection under weight loading of glass substrate and robot hand itself. In this thesis, a carbon/epoxy robot hand was analyzed using finite element method and beam theory to determine the deflection of the hand under the loading that is equivalent to actual weight. Because natural frequency is one of the major interests in robot hand design for TFT-LCD manufacturing process, modal analysis is also conducted using finite element method and beam theory. A robot hand was manufactured, and actual deflection and natural frequency were measured to verify the analysis results and compliance to requirement. The test results showed good agreement with analysis results.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.1
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• pp.69-75
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• 2016

Polydimethylsiloxane (PDMS) is used as a scaffold for cell culture. Because both the stress and strain acting on the substrate and the hemodynamic environment are important for studying mechano-transduction of cellular function, the traction force of the surface of a substrate has been measured using fluorescence images of particle distribution. In this study, deformation of the cross-sectional plane of a PDMS block was measured by correlating particle image distributions to validate the particle image strain measurement technique. Deformation was induced by a cone indentor and a shearing parallel plate. Measured deformations from particle image distributions were in agreement with the results of a computational structure analysis using the finite-element method. This study demonstrates that the particle image correlation method facilitates measurement of deformation of a polymer scaffold in the cross-sectional plane.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.137-137
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• 2000

The surface collective modes of thin K films deposited on Al(111) have been investigated using frequency dependent photoyield measurements and momentum resolved inelastic electron scattering. Jellium based theoretical calculations have predicted a richer set of features in the thin films than for the surface of a semi-infinite solid because there are th interference between two interfaces (substrate-film and film-vacuum) and heavy damping on the substrate. The use of an optical probe and electron scattering has allowed us to draw a more complete picture of the dynamic screening in thin films. The number, dispersion, damping and optical activity of the collective modes of the thin films have been measured as a function of K film thickness. New overlayer-induced excitations are observed : At qII=0, they correspond to the antisymmetric slab mode and the multipole surface plasmon. At finite qII=0, these modes undergo a transition towards the K multipole and monopole surface plasmons. With increasing coverage, the overlayer excitations turn into the collective modes of semi-infinite K. For a consistent interpretation of photoyield and electron energy loss spectra it is crucial to account for the non-analytic dispersion of the overlayer modes at small parallel wave vectors and for the finite angular resolution of the detector. The observed dispersions confirm predictions based on the time-dependent density functional approach.

• Journal of Powder Materials
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• v.15 no.3
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• pp.227-233
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• 2008

Dynamic plastic deformation behavior of copper particles occurred during the cold spray processing was numerically analyzed using the finite element method. The study was to investigate the impact as well as the heat transfer phenomena, happened due to collision of the copper particle of $20{\mu}m$ in diameter with various initial velocities of $300{\sim}600m/s$ into the copper matrix. Effective strain, temperature and their distribution were investigated for adiabatic strain and the accompanying adiabatic shear localization at the particle/substrate interface.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.215-222
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• 2007

Coating of Hot-dip galvannealed steel consists of various Fe-Zn intermetallic compounds. Since the coating is hard and there for is very brittle, the surface of steel sheet is easy to be ruptured during second manufacturing processing. This is called as powdering. In addition, forming equipment might be polluted with debris by powdering. Therefore, various research have been carried out to prohibit powdering fur improving the quality of GA steel. This paper carried out finite element analysis combined with damage model which simulate the failure of local layer of hot-dip galvannealed steel surface during v-bending test. Since the mechanical property of intermetallic compound was unknown exactly, we used the properties calculated from measurements. The specimen was divided into substrate, coating layer and interface layer. Local failure at coating layer or interface layer was simulated when elemental strain reached a prescribed strain.

• Advances in nano research
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• v.13 no.2
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• pp.113-120
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• 2022

In this paper, a finite element (FE) simulation has been developed in order to examine the nonlinear stability of reinforced sandwich beams with graphene oxide powders (GOPs). In this regard, the nonlinear stability curves have been obtained asuming that the beam is under compressive loads leading to its buckling. The beam is considered to be a three-layered sandwich beam with metal core and GOP reinforced face sheets and it is rested on elastic substrate. Moreover, a higher-order refined beam theory has been considered to formulate the sandwich beam by employing the geometrically perfect and imperfect beam configurations. In the solving procedure, the utalized finite element simulation contains a novel beam element in which shear deformation has been included. The calculated stability curves of GOP-reinforced sandwich beams are shown to be dependent on different parameters such as GOP amount, face sheet thickness, geometrical imperfection and also center deflection.

• Korean Journal of Materials Research
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• v.22 no.11
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• pp.636-641
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• 2012

In this study, we have investigated highly efficient nanoscale surface corrugated light emitting diodes (LEDs) for the enhancement of light extraction efficiency (LEE) of nitride semiconductor LEDs. Nanoscale indium tin oxide (ITO) surface corrugations are fabricated by using the conformal nanoimprint technique; it was possible to observe an enhancement of LEE for the ITO surface corrugated LEDs. By incorporating this novel method, we determined that the total output power of the surface corrugated LEDs were enhanced by 45.6% for patterned sapphire substrate LEDs and by 41.9% for flat c-plane substrate LEDs. The enhancement of LEE through nanoscale surface corrugations was studied using 3-dimensional Finite Different Time Domain (FDTD) calculation. From the FDTD calculations, we were able to separate the light extraction from the top and bottom sides of device. This process revealed that light extraction from the top and bottom sides of a device strongly depends on the substrate and the surface corrugation. We found that enhanced LEE could be understood through the mechanism of enhanced light transmission due to refractive index matching and the increase of light scattering from the corrugated surface. LEE calculations for the encapsulated LEDs devices also revealed that low LEE enhancement is expected after encapsulation due to the reduction of the refractive index contrast.

• Journal of Practical Engineering Education
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• v.6 no.2
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• pp.105-110
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• 2014

In this work, mechanical characteristics of titanium diaphragm have been studied as a potential robust substrate and a diaphragm material for automotive tire pressure sensor. Lamination process techniques combined with traditional micromachining processes have been adopted as suitable fabrication technologies. To illustrate these principles, capacitive pressure sensors based on titanium diaphragm have been designed, fabricated and characterized. The fabrication process for micromachined titanium devices keeps the membrane and substrate being at the environment of 20 MPa pressure and $200^{\circ}C$ for a half hour and then subsequently cooled to $24^{\circ}C$. Each sensor uses a stainless steel substrate, a laminated titanium film as a suspended movable plate and a fixed, surface micromachined back electrode of electroplated nickel. The finite element method is adopted to investigate residual stresses formed in the process. Besides, out-of-plane deflections are calculated under pressures on the diaphragm. The sensitivity of the fabricated device is $9.45ppm\;kPa^{-1}$ with a net capacitance change of 0.18 pF over a range 0-210 kPa.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.3
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• pp.57-62
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• 2012

In this paper, numerical analysis by finite element method, parameter design by the Taguchi method and ANOVA method were used to analyze about effect of design deviations and thickness variations on warpage of FCCSP substrate. Based on the computed results, it was known that core material in substrate was the most determining deviation for reducing warpage. Solder resist, prepreg and circuit layer were insignificant effect on warpage relatively. But these results meant not thickness effect was little importance but mechanical properties of core material were very effective. Warpage decreased as Solder resist and circuit layer thickness decreased but effect of prepreg thickness was conversely. Also, these results showed substrate warpage would be increased to maximum 40% as thickness deviation combination. It meant warpage was affected by thickness tolerance under manufacturing process even if it were met quality requirements. Threfore, it was strongly recommended that substrate thickness deviation should be optimized and controlled precisely to reduce warpage in manufacturing process.