• Journal of the Korean Magnetics Society
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• v.5 no.6
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• pp.947-951
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• 1995

The electromagnetic interference is prevented by the high magnetic loss of the ferrite. The absorbing property of electromagnetic wave could be improved by the ferrite that has a finer and more uniform microstructure. The thermal decomposition of organic acid salt provided the uniform composition and fine powder. The absorbing properties of electromagnetic wave were evaluated by the relative complex permeability, permittivity, and the attenuation which is calculated from the results of network analyzer. The permeability and permittivity were increased with increase of the density and with decrease of the grain size. The matching thickness could be reduced with increasing sintered temperature. The attenuation of the Cu-Ni-Zn ferrite showed over 20dB when the matching thickness and the matching frequency range were 6.75mm and from 160MHz to 640MHz, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.696-702
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• 2010

In many industrial applications, it is very important to control the temperature of the controlled object to the target temperature as closely as possible. Although it is apparent that the great obstacles in controller design are time-delay of the thermal responses of the controlled object and the effect of thermal interference between neighboring heating zones, one more fundamental obstacle is a very large amount of time which is required during repeated experiments in controller design process. Therefore, a convenient simulation environment, which can represent thermal behavior accurately within appropriate time, is needed. In this paper, a prototype of 2D FEM (finite element method) heat transfer simulation environment using MATLAB is constructed to be usefully adopted into industrial applications with temperature controller design.

• Journal of Ocean Engineering and Technology
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• v.6 no.1
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• pp.52-61
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• 1992

The steady laminar mixed convection from vertically misaligned, isothermal plastes has been studied by numerical procedure. The governing equations are solved by the finite difference method using successive using successive over relaxation scheme at Re=100-800, $Gr=10^3-10^6$, Pr=0.71 and dimensionless plate spacings b/L=0.1-1.0. The plume interaction caused by the thermal interference of twoplates is observed. As Reynolds numbers increase, the optimum plate spacings are moved to narrow spacings at the same Grashof number and as Grashof numbers increase, to wide spacings at the same Reynolds number.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.382-389
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• 2013

In anti-jamming GPS receiver, adaptive signal processing techniques in which the radiation pattern of adaptive array antenna of elements may be adaptively changed used to reject interference, clutter, and jamming signals. In this paper, I describes adaptive signal processing technique using the sample matrix inversion(SMI) algorithm. This adaptive signal processing technique can be applied effectively to wideband/narrowband anti-jamming GPS receiver because it does not consider the satellite signal directions and GPS signal power level exists below the thermal noise. I also analyzed the effects of covariance matrix sample size and diagonal loading technique on the system performance of five-element circular array antenna. To attain near optimum performance, more samples required for calculation covariance matrix. Diagonal loading technique reduces the system nulling capability against low-power jamming signals, but this technique improves robustness of adaptive array antenna.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.106-109
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• 2001

The use of ceramic inserts in hot extrusion dies offers significant technical and economic advantages over other forms of manufacture. These potential benefits can however only be realized by optimal design of the tools so that the ceramic inserts are not subjected to stresses that lead to their premature failure. In this paper, process simulation and stress analysis are thus combined during the design, and a data exchange program has been developed that enables optimal design of the dies taking into account the elastic deflections generated in shrink fitting the die inserts and that caused by the stresses generated in the process. The stress analysis of the dies is used to determine the stress conditions on the ceramic insert by considering contact and interference effects under both mechanical and thermal loads. The results are compared with the experimental ones for verification.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.349-352
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• 1997

The EEG amplifier satisfies high gain, high common mode rejection ratio(CMRR), high input impedance, low thermal drift, low noise and good d.c. performance. The Bipolar amplifier of this paper safisfies above categories and aim at minimization of the ESU(electric surgical unit) interference.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.2
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• pp.313-319
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• 2010

GNSS receiver which uses the weak satellite signal is very vulnerable to the intentional jamming or non-intentional electromagnetic interference. One of the best method to overcome this disadvantage is to use an adaptive array antenna which has the capability of beamforming or nulling to the certain direction. In this paper, the performance of spatial adaptive null pattern control algorithm of 5 element array antenna is analyzed. A control algorithm which is designed in the 5 element array antenna is OPM(Output Power Minimization) which is eliminating the correlation characteristics between a reference antenna and the others. This algorithm can be applied effectively to the satellite navigation's CRPA because the satellite direction is not considered and GNSS signal power is below the thermal noise. The feature of the OPM algorithm is analyzed and the performance is compared with other null pattern control algorithm.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.1
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• pp.32-37
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• 2002

The use of hexagonal ceramic inserts for copper extrusion dies offers significant technical and economic advantages over other forms of manufacture. In this paper the data on the loading of the tools is determined from a commercial FEM package as the contact stress distribution on the die-workpiece interface and as temperature distributions in the die. This data can be processed as load input data for a finite element die-stress analysis. Process simulation and stress analysis are thus combined during the design and a data exchange program has been developed that enables optimal design of the dies taking into account the elastic deflections generated in shrink fitting the die inserts and that caused by the stresses generated in the process. The stress analysis of the dies is used to determine the stress conditions on the ceramic insert by considering contact and interference effects under both mechanical and thermal loads.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.72-77
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• 2001

The use of hexagonal ceramic inserts for copper extrusion dies offers significant technical and economic advantages over other forms of manufacture. In this paper the data on the loading of the tools is determined from a commercial FEM package as the contact stress distribution on the die-workpiece interface and as temperature distributions in the die. This data can be processed as load input data for a finite element die-stress analysis. Process simulation and stress analysis are thus combined during the design, and a data exchange program has been developed that enables optimal design of the dies taking into account the elastic deflections generated in shrink fitting the die inserts and that caused by the stresses generated in the process. The stress analysis of the dies is used to determine the stress conditions on the ceramic insert by considering contact and interference effects under both mechanical and thermal loads.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1645-1651
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• 1990

The steady laminar mixed convection from two finite vertical parallel plates has been studied by numerical procedure. The governing equations are solved by the finite difference method and point successive over relaxation scheme at R3=100-1000, Gr=0-10$^{6}$ , Pr=0.71 and dimensionless plate spacing b/$\ell$=0.05-0.1. The plume interaction caused by the thermal interference of two plates is observed. As Reynolds numbers are increased, optimum plate spacings are moved to narrow spacings at the same Grashof number, and as Grashof numbers are increased, to wide spacings at the same Reynolds number.