• Journal of Navigation and Port Research
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• v.30 no.5 s.111
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• pp.363-367
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• 2006

The frequency band $10.5GHz\sim10.7GHz$ provides some of the best angular resolutions using many large and accurate radio telescopes. Developing high performance Bandpass Filter is needed for these equipments to receive low power signals from the space. In this paper, suggests Bandpass Filter for Radio Astronomy equipments. Designed by Microstrip Line for good pass characteristic and suppressing not necessary signals cause of using high frequency. Center frequency is 10.6 GHz and band width is 5% of Center frequency. Manufactured Bandpass Filter is suitable for Radio Astronomy Equipments. Bemuse it matches up to the result by simulate.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.121-125
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• 2006

The frequency band $10.5GHz{\sim}10.7GHz$ provides some of the best angular resolutions that using many large and accurate radio telescopes. Developing high-performanced Bandpass Filter is needed for these equipments receive low power signals from the space. In this paper, Bandpass Filter for Radio Astronomy equipments is proposed. It is designed by Microstrip Line for good pass characteristic and suppressing unwanted signals. Center frequency is 10.6 GHz and band width is 5% of Center frequency. Manufactured Bandpass Filter is suitable for Radio Astronomy Equipments. Because the measured results agree well with the simulation results.

• Journal of the Korea Convergence Society
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• v.2 no.2
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• pp.7-12
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• 2011

In this study, we investigate on location optimization algorithm of radio-navigation transmitter. The DOP for an each receiver is decided by the location of a transmitter. We provide various results that give an optimum DOP according to propagation characteristics. We use the DTED(Digital Terrain Elevation Data) to improve the accuracy.

• Journal of Navigation and Port Research
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• v.35 no.9
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• pp.717-720
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• 2011

In this paper, we designed and fabricated the Electromagnetic(EM) wave absorber for an Electronic Toll Collection(ETC or Hi-pass) system by using Amorphous metal powder and CPE. The material properties and the absorption properties of the samples containing 50 wt.%, 60 wt.%, 70 wt.%, and 80 wt.% of Amorphous. Moreover, the EM wave absorption abilities were simulated for the different thicknesses of the EM absorbers by adopting the measured permittivity and permeability, and then the EM wave absorber was fabricated based on the simulated design values. As a result, the EM wave absorber with the composition of Amorphous metal powder : CPE = 50 : 50 wt.% with the thickness of 2.6 mm has excellent absorption ability more than 40 dB at 5.8 GHz.

• Journal of Advanced Navigation Technology
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• v.12 no.5
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• pp.429-436
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• 2008

In this paper, we study an optimization which determines the optimal sensing time and the number of cooperative sensing cognitive users for cooperative spectrum sensing scheme in cognitive radio networks. In cooperative spectrum sensing, cognitive users originally in inactive status are activated and take part in spectrum sensing along with transmitting cognitive users resulting in a reduced sensing time. Tradeoff between transmission rate gain and energy consumption due to cooperative sensing is formulated as a mixed integer programming problem which is solved for the optimal values.

• Journal of Navigation and Port Research
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• v.35 no.4
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• pp.299-302
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• 2011

In this letter, the effect of quality factor on center frequency deviation in miniaturized coupled line bandpass filter (BPF) with diagonally end-shorted at their opposite sides and lumped capacitors is theoretically analyzed. The miniaturized BPF of a two-stage structure with two types of quality factors in standard CMOS process was designed and manufactured at 5.5 GHz. The die area of BPF was $1.44{\times}0.41\;mm^2$. The measured center frequency of BPF with a quality factor of 4.9 was deviated from 5.5 GHz to 4.7 GHz. The one with 14.8 was shifted to 5GHz. The theoretical and measured results validate that quality factor influences the center frequency shift of BPF.

• Journal of Navigation and Port Research
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• v.34 no.7
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• pp.543-552
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• 2010

Modified compact combline bandpass filters are proposed based on the miniaturized quarter-wave transmission line which is composed of the parallel coupled line and lumped capacitors. The electrical length of the parallel coupled line in a resonator, which determines the size of combline bandpass filters, is just $5^{\circ}$ or $7^{\circ}$, resulting in a compact circuit area. The designed combline bandpass filter also has a wide upper stopband by suppressing the spurious passbands, not moving. Measured results of two fabricated filters centered at 400MHz show good agreement with the theoretical predications.

• Journal of Advanced Navigation Technology
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• v.13 no.4
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• pp.475-481
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• 2009

This paper focuses the performance improvement of the train radio system (TRS) supporting the safe and accurate operations. The causes of troubles and the performance drift in TRS have been analyzed and measurement indexes have been selected. Frequency shifts of transmitters causing from train vibrations have been shown, and the improvement of frequency stability has been confirmed by use of vibration- proof pads.

• Journal of Navigation and Port Research
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• v.34 no.4
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• pp.299-304
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• 2010

In this paper, the EM wave absorber was developed for the 94-GHz detecting radar system. To analysis an EM wave absorber in millimeter wave band, we fabricated three absorber samples using carbon black and titanium dioxide and permalloy with chlorinated polyethylene. After measuring the complex relative permittivity, the absorption characteristics are simulated by 1D FDTD according to different thicknesses of less than 1.0 mm. Then, the EM wave absorber was fabricated based on the FDTD simulation. As a result, the measured results agreed well with the simulated ones, and the developed EM wave absorber with a thickness of 0.7 mm had the desired absorption characteristics of more than 14 dB in the frequency range of the 94-GHz band.

• Journal of Advanced Navigation Technology
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• v.9 no.2
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• pp.192-199
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• 2005

Adaptive Modulation & Coding (AMC) is the method of varying the modulation and coding scheme for the changeable wireless channel environment. WiBro use AMC method because it has a very large variation caused by mobility interference and other cell interference. In this paper, we will compare and analysis the method of selecting the optimum MCS level for the efficiently use of mobile power consumption.