• Journal of electromagnetic engineering and science
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• v.18 no.3
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• pp.160-168
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• 2018

A wide spectrum of potential applications using substrate integrated waveguide (SIW) technologies in conjunction with air hole regions is introduced, and an efficient optimization methodology to cope with the multiple air hole effect in SIW applications is proposed. The methodology adopts a genetic algorithm to obtain optimum air hole dimensions for the specific propagation constant that can be accurately calculated using the recursive and closed form equations presented. The optimization results are evaluated by designing an SIW bandpass filter, and they show excellent performance. The optimization methodology using the proposed equations is effective in performance enhancement for the purposes of low loss and broadband SIW applications.

• Journal of electromagnetic engineering and science
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• v.18 no.3
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• pp.182-187
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• 2018

A low profile asymmetrical fractal boundary patch antenna based on reactive impedance surface (RIS) and a mushroom unit cell (MUC) is proposed and studied for dual band operation. The sides of the square patch antenna are replaced with asymmetrical half circled fractal curves for circular polarization operation at patch mode band. The fractal patch antenna is loaded with MUC for dual band operation. The antenna radiation characteristics are investigated and illustrated with both simulated and experimental results in detail. The 10-dB return loss bandwidth are 8.48% (3.21-3.49 GHz) and 2.59% (2.30-2.36 GHz) at upper and lower resonance frequencies, respectively. The 3-dB axial ratio bandwidth is 4.26% (3.21-3.35 GHz). A close agreement between simulation data with experimental results is observed.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.1
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• pp.66-74
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• 1992

The joining processes of aluminum alloy tubes and polyurethane cores by electromagnetic impulsive compression are studied. The influences of various geometrical factors (the length of joined part, the thickness of tube, and the clearance between tube and core) and the process factors(the discharged energy and the number of discharge)are examined experimentally and discussed. And the magnetic pressure in metal/polymer joining is calculated and is compared to the pressure in metal/metal joining. The following results are obtained: (1) The joining strength is dependent upon the residual radial strain of the polyurethane cores. (2) The joining strength increases as discharged energy and the number of discharge increase, but decreases as the clearance, thickness and joining length of tube increases. (3) In the case of metal/polymer joining energy loss is increased and the value of magnetic pressure is less than that in the case of metal/metal joining.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2203-2204
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• 2006

When the coil with alternating current approaches to the conductor the eddy current flows in conductor. Eddy current is concentrated on the conductor surface and decrescent because of skin effet.. In this paper investigated eddy current characteristic that is happened in conductor. Analyzed characteristic using electromagnetic field finite element analysis program that is commercialized to analyze value of eddy current and penetration depth. Analyzed creation value of eddy current and penetration depth in conductor that change operation frequency and the material of conductor, coil outside diameter, inside diameter, position, type of conductor from analyzed eddy current characteristic. The results. using distribution of eddy current and penetration depth data is that will help to forecast ECT(Eddy Current Testing), Eddy current application and use field, eddy current loss.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.571-572
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• 2006

When the coil with alternating current approaches to the conductor the eddy current flows in conductor. Eddy current is concentrated on the conductor surface and decrescent because of skin effet.. In this paper investigated eddy current characteristic that is happened in conductor. Analyzed characteristic using electromagnetic field finite element analysis program that is commercialized to analyze value of eddy current and penetration depth. Analyzed creation value of eddy current and penetration depth in conductor that change operation frequency and the material of conductor, coil outside diameter, inside diameter, position, type of conductor from analyzed eddy current characteristic. The results, using distribution of eddy current and penetration depth data is that will help to forecast ECT(Eddy Current Testing), Eddy current application and use field, eddy current loss.

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.28-33
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• 2002

The LHCP circularly polarized antenna operating at DBS band is developed by employing the sequential-rotation technique in which each subarray is comprised the three truncated-corner patch square element. Antenna designed with sequentially-related technique whose M=3, p=2 has the effect of improved axial-ratio bandwidth, cross-polarization etc. And it is proved that the degradation of radiation pattern can be reduced significantly by minimizing the radiation loss of feeding line structure. Antenna designed shows extremely low side lobe level of below - 25 dB in the diagonal plane and cross-polarization level of below -20 dB in the all plane. And these performances comply with the array antenna specification for DBS.

• Journal of electromagnetic engineering and science
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• v.7 no.3
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• pp.103-108
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• 2007

In this paper, a low-power 2.4 GHz front-end for sensor network application (IEEE 802.15.4 LR-WPAN) is designed in a 0.18 um CMOS process. A power supply circuit with a novel temperature-compensation scheme is presented. The simulation and measurement results show that the front-end (LNA, Mixer) can achieve a voltage gain of 35.3 dB and a noise figure(NF) of 3.1 dB while consuming 5.04 mW (LNA: 2.16 mW, Mixer: 2.88 mW) of power at $27^{\circ}C$. The NF includes the loss of BALUN and BPF. The low-IF architecture is used. The voltage gain, noise figure and third-order intercept point (IIP3) variations over -45$^{\circ}C$ to 85$^{\circ}C$ are less than 0.2 dB, 0.25 dB and 1.5 dB, respectively.

• Journal of electromagnetic engineering and science
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• v.7 no.3
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• pp.116-121
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• 2007

Novel design of a wideband monopole antenna for DVB-H service is presented. The proposed antenna is designed based on a monopole antenna. It consists of folded monopole and parallel parasitic element. The folded segment of the folded monopole makes the antenna shorter. The length of the parasitic element obtains additional resonance frequencies. The gap distance between the folded monopole and the parasitic element is a key parameter to control impedance matching for wideband operation. The antenna has wide band performance, good impedance and radiation characteristics from 470 MHz to 870 MHz. The measured return loss for operating frequencies over DVB-H band is better than 10 dB. Good radiation patterns are also obtained. The measured results are compared with calculated results using Ansoft HFSS(High Frequency Structure Simulator).

• Journal of electromagnetic engineering and science
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• v.7 no.3
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• pp.129-133
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• 2007

In this paper, we present the development of an antenna specialized for the maritime collision avoidance system. This antenna is configured as the dielectric rod partially embedded in the metal cavity to reduce the overall size, simultaneously assuring the mechanical sturdiness against the challenging oceanic weather conditions. More importantly, the design has been carefully done to meet the requirements on the radiation pattern(with the slope < 5 dB/deg in the elevation(E-plane), circular in the azimuth) suitable to receiving the reflected signals from the other objects on the sea. To find the optimal design parameters, the genetic algorithm has been used to meet the goals of the desired return loss and pattern. This design methodology is validated by the good agreement between the calculation and measurement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.483-486
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• 2014

Although flip-chip interconnects have smaller parasitics than bonding wires, they should be carefully designed at 60 GHz. Insertion loss at a flip-chip transition may differ as much as 2 dB depending on design parameters. In this paper we present a comprehensive sensitivity analysis to optimize the flip-chip transition.