• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.11
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• pp.440-444
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• 1985

Voltage equations of a synchronous machine are derived from the electromagnetic field theory in order to develop a new equivalent circuit model considering core loss. The result from the new equivalent circuit model is superior to that of the conventional one in the analysis of machine performance and characteristics on optimal efficiency control of a synchronous motor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.9
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• pp.701-706
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• 2018

The characteristic basis function method, or CFBM, is one of the representative electromagnetic methods widely used today. In this paper, we propose an accelerating algorithm for the far field interaction calculation of CBFM, to efficiently analyze the electromagnetic characteristics of arbitrarily large structures. To effectively analyze the electromagnetic characteristics of a large structure, it is essential to shorten the computation time. In the CBFM analysis method, the complexity can be greatly reduced by using approximations created via the multipole expansion method. The new algorithm proposed in this paper is applied to the computation of radar cross sections of conductor spheres and fighter aircraft, and it is confirmed that calculation time is reduced by 34 % and 74 %, respectively, without loss of accuracy compared with existing CBFM.

• Journal of electromagnetic engineering and science
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• v.5 no.3
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• pp.140-145
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• 2005

In this paper, an experimental investigation for return loss and a software-based prediction for interference level of single-packaged filtering antenna composed of dielectric waveguide filter and PCB(Printed Circuit Board) slot antenna in transceiver module have been carried out with several different feeding structures in millimeter-wave regime. The implementation and embedding method of the existing air-filled waveguide filters working at millimeter-wave frequency on general PCB substrate have been described. In a view of the implementation of each components, the dielectric waveguide embedded in PCB and LTCC(Low Temparature Co-fired Ceramic) substrates has employed the via fences as a replacement with side walls and common ground plane to prevent energy leakage. The characteristics of several prototypes of filtering antenna embedded in PCB substrate are considered by comparing the wideband and transmission characteristics as a function of bent angle of transmission line connecting two components. In addition, as an essential to the packaging of transceiver module working at millimeter-wave, miniaturization technology maintaining the performances of independent components and the important problems caused by integrating and connecting the different components in different layers are described in this paper.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.270-277
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• 2013

In this paper, we propose a wideband ridge SIW(Ridge Substrate Integrated Waveguide)-to-SIW(Substrate Integrated Waveguide) transition. The proposed transition structure is designed to acquire a wide bandwidth by inserting through via holes at the regular interval for an impedance matching and an E-field mode matching method. The measurement results show a fractional bandwidth is 29.1 % at 20 dB return loss from the center frequency(11 GHz). The maximum insertion loss is 0.49 dB from 9.21 GHz to 12.41 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.11
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• pp.1047-1054
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• 2013

In this paper, we propose a dual-mode mixer to have multi-band radar signal receiver to be compact. The proposed mixer using a anti-parallel diode is operated as a fundamental mixer or sub-harmonic mixer with respect to a control voltage. A fundamental mixer with a control voltage show a conversion loss of -10 dB, 1dB compression point of 2 dBm at X-band. On the other hand, it is performed as a sub-harmonic mixer with a conversion loss of -10 dB, 1 dB compression point of 2 dBm at K-band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.457-463
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• 2018

This paper compares the results of ${\Sigma}{\Delta}-STAP$ applied to actual radar test data and simulation data. The radar received a target signal from a virtual target generator and the clutter signal from a signal generator in an anechoic chamber. The simulation data were generated from ideal baseband radar signal modeling using the same parameter as that for the test radar. The ${\Sigma}{\Delta}-STAP$ results of the test and simulation data are similar in terms of the target signal shape and noise level. The SINR(Signal-to-Interfrence-plus-Noise Ratio) loss also had similar aspects, but the simulation result shows 1~2 dB higher SINR loss than the test result. This result verified that the simulation data can be a reasonable alternative test data when the ${\Sigma}{\Delta}-STAP$ is applied.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.2
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• pp.165-175
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• 2001

In this paper, it is analyzed lumped element isolators analytically by the analysis program using scattering matrixes including ferrite saturation magnetization, external direct current magnetic field and strip line length and width, designed and experimented the small isolator of mobile phone. The simulation results show that the characteristics of the isolator are affected by external R, C, length and width of strip line and ferrite width and saturation magnetization sensitivity. We proposed the isolator specification applied cellular and PCS mobile phones, experimented the isolator for cellular mobile phones. From the experimented result, isolation and return loss are measured below 20 dB, insertion loss is below 0.7 dB, bandwidth is about 44 MHz at center frequency 836.5 KHz. The implemented isolator has better performances than the conventional one.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.2
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• pp.199-207
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• 2001

In this paper, the technique of prediction and analysis on the characteristics of propagation in indoor environment is presented. This technique needs no reception sphere commonly used in 3D-ray tracing scheme, and thereby it lends us easy code realization. The validity of developed code is verified by comparing with the values of image methods and measurement. The developed technique applied to the structure of rectangular corridor with the iron door and we calculated the path loss for the variation of the iron door angle. The path loss decreased about 15 dB at the distance of30 m from the iron door and the delay spread increased approximately by four times. Based on the computation, we confirmed that indoor propagation in PCS is heavily affected by the iron door in corridor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.7 s.98
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• pp.746-752
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• 2005

In this paper, optical noise effect is reduced by using the loss characteristics of plastic fibers in an optical wireless system. The attenuation coefficient of a plastic fiber for the signal is different from that f3r the noise light, and the length difference between two fibers to the 2PD's behaves like a discriminative element. It is possible to eliminate the optical noise effect and detect only the signal without optical filters. The signal to noise ratio in a differential detector using fibers was 9.7 dB higher than in a single photodiode without optical fiber.

• Journal of the Korean Ceramic Society
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• v.43 no.2 s.285
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• pp.74-78
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• 2006

A non-integrated type noise filter on a Coplanar Waveguide (CPW) transmission line is demonstrated by using a highly resistive $Co_{41}Fe_{38}Al_{13}O_8$ nanogranular thin film with the dimensions of $4\;mm (\iota)\times4\;mm(\omega)\times0.1\;{\mu}m(t)$. The noise suppression characteristics are evaluated without placing an insulating layer between the CPW line and the magnetic thin film. The insertion loss is very low being less than 0.3 dB and this low value is maintained up to 2 GHz. At a ferromagnetic resonance frequency of 3.3 GHz, the power loss is very large and the degree of noise attenuation is measured to be 3 dB. This level of noise attenuation is still small for real applications; however, considering the small magnetic volume used in this work, further improvement is expected by simply increasing the magnetic volume and by integrating the magnetic thin film into the CPW transmission line.