• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.52-59
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• 2006

To construct its complex permittivity from the reflection coefficient of a thin film such as PCB substrate measured by open-ended coaxial probe, an integral equation is formulated using modal analysis and equivalent source. The accuracy of the conversion model based on the integral equation is confirmed in both cases of converted complex permittivities calculated from numerically computed and actually measured reflection coefficients. And the maximum valid frequency of open-ended coaxial probe is limited by the size of its flange.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.11 s.102
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• pp.1099-1105
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• 2005

TRL error correction method is widely used for measuring high frequency device mounted on PCB. In order to correct error more precisely, the characteristic impedance of standard transmission line should be known mounted for error correction. The capacitance per the unit length of transmission line is calculated by using standard transmission line which terminate resistor additionally at previous method and the characteristic impedance of standard transmission line is calculated with fitting method according to frequency, but the characteristic impedance extracted by a manufacturing inaccuracy is influenced. In this study, a novel method can reduce the manufacturing inaccuracy using measured s-parameters and can extract more accurate characteristic impedance than the previous method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.109-121
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• 1999

In this paper, HF band LPDA(Log-periodic Dipole Antenna) and MLPDA(Modified Log-periodic Dipole Antenna) above lossy grounds were analyzed using moment method by considering the practical media parameter of lossy grounds, not assuming free space or perfect ground approximation. The radiation pattern and gain of LPDA and MLPDA as functions of frequency, antenna height from ground, and antenna tilt angle are presented, and the lossy ground effect on antennas characteristics are described. MLPDA was found to exhibit a smaller variation for gain and radiation pattern and a higher maximum beam direction relative to LPDA. It was shown that media parameter of lossy grounds and antenna height have a direct influence on the antenna gain of both LPDA and MLPDA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.1-10
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• 1999

In this paper, a method of canceling and suppressing differential-mode crosstalk-noise signals caused by non-uniform coupling between two transmission lines in UTP(Unshielded Twisted Paris) modular jacks is discussed. Differential-mode crosstalk-noise signals in balanced transmission lines in UTP modular jacks were suppressed by inserting auxiliary capacitance between balanced transmission line pairs which are located closely enough to be effectively coupled each other. To verify the effectiveness of the inserted capacitances, precisely calculated auxiliary capacitances were applied to 10 pin modular jacks which are used in local area networks at 100 Mb/s with unshielded twisted pair-cables. The NEXT(Near-End Crosstalk) losses were measured to prove its applicability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.11 s.102
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• pp.1067-1074
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• 2005

Studied antenna's basic structure was circular micro-strip patch antenna. Bandwidth was broaden and back-radiation pattern was decreased because studied antenna had PBG on a ground for improvement in its defect which is skin-effects. And character of antenna according to different shape of PBG was observed. Finally, air-gap whose dielectric constant is lower than substrates was added between substrates sc respond frequency was higher despite small size antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.7
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• pp.588-598
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• 2016

In this paper, we studied a policy direction for promoting radio industry by analyzing the ecosystem. For this, we drew the growing structure and mechanism of radio industries according to wireless technology and service development. We suggested policy elements for radio industry promotion, which is composed of technology development, service development, advancement of law and regulations, business model development, assistance of production and use, publicity enforcement for promotion. The concept and radio industry sector practices of the ecosystem analysis are analyzed by survey of experts. From this result, the 5 policy options are proposed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1063-1069
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• 2011

NCTR(Non-Cooperative Target Recognition) and ATR(Automatic Target Recognition) are methodologies to identify military targets using radar, optical, and infrared images. Among them, a strategy to recognize ground targets using synthetic aperature radar(SAR) images is called SAR ATR. In general, SAR ATR consists of three sequential stages: detection, discrimination and classification. In this paper, a modification of the polar mapping classifier(PMC) to identify inverse SAR(ISAR) images has been made in order to apply it to SAR ATR. In addition, a preprocessing scheme can mitigate the effect from the clutter, and information on the shadow is employed to improve the classification accuracy.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1136-1142
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• 2010

In this paper, we reduced the optical noise interference using the ASK modulation with optoelectronic feedback in a wireless optical system in which a lighting LED is used as a light source. The carrier frequency of 70 kHz was generated internally by the oscillation in the optoelectronic feedback circuit, and the output light was ASK modulated at a data rate of 9.6 kbps by opening and shortening the feedback loop with the input signal. In an environment with adjacent noise lights, the ASK modulation with optoelectronic feedback improved the signal to noise ratio by about 25 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1201-1207
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• 2010

As the mobile services have been increased, the PIMD(Passive Inter-Modulation Distortion) as well as the active-IMD of the CDMA system should be considered for the design of base station antenna systems, because they have an interference of the neighboring base stations. In this paper, in order to reduce the nonlinearity of current caused by the local point contact, we have investigated an influence of the combination of nuts, contact torque(kgf.cm), and the contact area on the PIMD. We propose the improvement techniques of PIMD by investigating the effects of the distance of nuts, the contact area, and the type of nuts.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1085-1093
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• 2010

This paper proposes a multiple filter for reduction of received signal fluctuation and enhancement of step altitude edge detection in FMCW radar altimeter. The proposed filter was composed of alpha-trimmed mean filter, frequency variation limiter, and 1/3 order static filter. Simulations by analysis of received signal show that the proposed filter provides better performance than moving average and standard median filters with error reduction. In particular, the proposed filter was improved in the ability of reducing fluctuation for ground hovering.