• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.2
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• pp.45-58
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• 2011

Gravure off-set printing recently is used in electronics display market. This method has advantages of mass production and high printing speed. It is also fine pattern can be implemented. We have manufactured low-curable conductive Ag pastes for gravure off-set printing. When printing, the pastes be used different silver powder shape because of the printing characteristics. The pastes were prepared with silver powder by silver powder shape and size, epoxy resin, solvent and homogenized on a standard three-roll mill. And the pastes exhibited a shear-thinning flow at viscosity profile. Moreover the adhesive strength and resistivity of silver film had a good characteristics. With the manufactured paste in this study, touch panel had is manufactured and it had $4{\times}10-5{\Omega}.cm$.

• Journal of ILASS-Korea
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• v.2 no.2
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• pp.8-15
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• 1997

Combustion chamber systems using spray impinged on walls have been studied for improving combustion characteristics in high speed direct injection diesel engines. The fuel spray injected in a small combustion chamber may be easily impinged and deposited on the wall. The fuel deposit has been considered as the cause for unburned emission due to difficulty of fuel-air mixing. In this paper w-shaped combustion chamber which has four raised pips on the side wall is introduced and discussed by comparing with conventional chamber with no pips. The computer code employing new spray-wall interaction model in general non-orthogonal grids is used in here. The model is applied into the new chamber shape with raised pips. In this chamber system four-hole nozzle is used, and the sprays injected from the each hole impact on lands raised from the chamber wall surface. After impacting, the sprays break up into much smaller drops and distribute over all the chamber space, instead of distributing just near the wall surface in conventional omega-shape. The results showed the potential of the w-shaped chamber employing pips for dispersing droplets so as tn avoid the fuel deposit regions.

• 한국연소학회:학술대회논문집
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• 1998.10a
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• pp.123-129
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• 1998

A numerical study has been conducted to investigate the effect of shock waves on the mixing and the recirculation zone of a hydrogen jet diffusion flame in a supersonic combustor. The general trends are compared with the experimental results obtained from the supersonic combustor at the University of Michigan. For the numerical simulation of supersonic diffusion flames, multi-species Navier-Stokes equations and detailed chemistry reaction equations of $H_2$-Air are considered. The $K-{\omega}/k-{\varepsilon}$ blended two equation turbulent model is used. Roe's FDS method and MUSCL method are used for convection fluxes in governing equations. Numerical results show that when slender wedges are mounted at the combustor wall the mixing and the combustion are enhanced and the size of recirculation zone is increased . The flame shape of supersonic flames is different in the flame-tip; it is not closed but open. The flame shape is shown to be greatly affected by shock waves.

• Journal of the Korea society of information convergence
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• v.5 no.2
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• pp.101-108
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• 2012

In the present paper, it removed the low frequency noise under 1Hz which get up base wandering from the various noise which is included in ECG signals. It used wavelet filter, FIR filter and Adaptive FIR filter and compared the efficiency of the filter. The set condition of 3 kind filters which are the comparative object is the next contents. Used wavelet case, used generating functions db7 and after decomposition, the low frequency of 8 phases (cA8) replaced at 0. FIR filter case, filter coefficient set 1400, cutoff frequency (${\omega}$) set 0.002. Adaptive FIR filter case, collecting coefficients (${\mu}$) with 0.005. The comparative result from the output wave shape and FT spectrum, wavelet is excellent in base wandering removals compared FIR filter and Adaptive FIR filter. And SNR comparisons, wavelet filter(44.16) is high compare with other two filters(25.19 and 15.94).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.225-233
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• 2002

The flexural vibration characteristics of a sandwich beam system with a partially inserted viscoelastic layer have been quantitatively studied using a finite element analysis in combination with a sine-sweep test. Antisymmetric mode shapes of the flexural vibration were visualized by the holographic interferometry and agreed with those calculated by the finite element simulation. Effects of the beam thickness as well as the length and thickness of partial viscoelastic layers on the system loss factor(η$\_$s/) and resonant frequency($\omega$$\_$r/) were significantly large fur the symmetric and antisymmetric modes of the beam system.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.237.1-237.1
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• 2011

Resistivity of GaN has been investigated under the influence of ion implantation. n-type, p-type and also undoped GaN has been used here. A ring shape pattern of Au was fabricated on GaN film by the photolithography technique. H, He and Ar were used for implantation. The ion implantation energy, fluence and post-implant annealing temperature varied in this research. Because of the making barrier in some selected area using ions, the resistivity changed in all the samples with the change of both fluence and energy. At room temperature, the resistivity of n-type GaN has been increased from $1.9{\times}10-2$ to $17.7{\times}10-2\;{\Omega}-cm$. This is high for He ion. But undoped and p-type GaN showed some anomalous character.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.2
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• pp.11-15
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• 2013

We in order to use WLAN communication device planned wireless USB dongle internal antenna of 2.4 GHz/5.8 GHz band. So it uses square patch dual-wideband and quality is satisfactory and it designed print folded monopole antenna of the shape which is simple. The thickness of the antenna was fed by a $50{\Omega}$ coaxial cable feeding 1mm dielectric constant 4.4 FR4 substrate was used. The overall size of the antenna is $20mm{\times}50mm$. So the internal antenna is suitable. Measurement results of the fabricated antenna, the return loss of more than 10 dB in the two bands could be obtained. Radiation pattern has a maximum gain of 3.75 dBi value.

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.11-15
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• 2002

High speed probe for measurement of sin91e flux quantum circuits is comprised of coaxial cables and microstrip lines in order to carry high speed signals without loss. For the impedance matching between coaxial cable and microstrip line, we have determined the dimension of the microstrip line with 50${\Omega}$ impedance by simulation and then have investigated the effect of line width and cross-sectional shape of signal line, dielectric material, thickness of soldering lead at the coaxial-to-microstrip transition Point, and the an91c between dielectric material and end part of the signal line on the characteristics of signal transmission of the microstrip line. From the simulation, we have found that these all parameter's had influenced on the characteristic of signal transmission on the microstrip line and should be reflected in fabricating high speed probe, We have also determined the dimension of coplanar waveguide to fabricate testing sample for performance test of high speed probe.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.681-684
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• 1999

N-methyl phenazinium 7, 7, 8, 8-tetra-cyanoquinonedimethane (TCNQ) complex salt was synthesized and bar-coated on PET film using various binders. Optical microscope and SEM reveals that TCNQ complex salt crystals were grown on the surface of binders and the shape was different with binders. The surface resistivity was 1$^{5}$ $\Omega$/$\square$ when binders has compatibility with TCNQ complex salt.

• 한국전산유체공학회:학술대회논문집
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• 2002.05a
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• pp.79-87
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• 2002

The present work analyzed the effect of mixing vane shape on the flow structure and heat transfer downstream of mixing vane in a subchannel of fuel assembly, by obtaining velocity and pressure fields, turbulent intensity, flow-mixing factors, heat transfer coefficient and friction factor using three-dimensional RANS analysis. NJl5, NJ25, NJ35, NJ45, which were designed by the authors, were tested to evaluate the performances in enhancing the heat transfer. Standard $\kappa-\epsilon$ model is used as a turbulence closure model, and, periodic and symmetry conditions are set as boundary conditions. The flow blockage ratio is kept constant, but the twist angle of mixing vane is changed. The results with three turbulence models( $\kappa-\epsilon$, $\kappa-\omega$, RSM) were compared with experimental data.