• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.293-296
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• 2004

This paper proposes an architecture of channel estimation for multi-band OFDM UWB systems presented to IEEE 802.15.3a by Multi-band OFDM alliance(MBOA). The multi-band OFDM (MB-OFDM) systems should have channel estimation for compensation of signal distortion by multi-band channel. The moving-averaging estimation algorithm and multi-band equalization architecture for MB-OFDM UWB systems proposed in this paper was verified by the simulation. Simulation results show that MB-OFDM system with the proposed architecture have the performance improved by about 3.4 dB compared to system with no channel estimation in 0.1$\pi$ phase-rotated channel.

• Journal of Digital Contents Society
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• v.7 no.1
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• pp.41-45
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• 2006

In this paper, we introduced the dual-band and multi-band slot loaded patch antenna for multi services. This antenna has the characteristic of dual-band and multi-band antenna by 4 slots nearly located in the edges of a patch. By changing the number and location of probe, the width and length of slot, and the distance between slot and the edge of patch, we studied the performance of dual-band and multi-band characteristic.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.533-534
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• 2008

This paper presents a multi-phase ring VCO for low-cost, low-power GPS receiver. In the RF band used in GPS, L1 band is now in commercial-use and L2,L5 are predicting to be commercial-use soon. Thus Wide band PLL and Cost-effective IC solutions are required for future multi-band GPS receiver that received three types band at once. A new PLL architecture for multi-band GPS application is proposed. Ring VCO is even smaller than LC-VCO and a good alternative for low-cost solution. Proposed multi-phase ring VCO offers wide frequency range covering L1, L2, and L5 band, 20% reduction of area, 23% reduction of PLL power and can generate I/Q without extra I/Q generator.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.332-335
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• 2008

Newly developing SAR (Synthetic Aperture Radar) sensors commonly include high resolution X-band those data are expected to contribute various applications. Recent few studies are presenting potential of X-band SAR data in forest related application. This study tried to investigate the relationship between forest stand parameters and multi-band SAR normalized backscattering. Multi-band SAR data was radiometric corrected to compare signal from different forest stand condition. Then correlation coefficients were estimated between attribute of forest stand map and normalized backscattering coefficients. Although overall correlation coefficients are not high, only X-band shows strong relationship with DBH class than other bands. The signal of C- and L-band is composed of a large number of discrete tree components such as leaves, stems, even background soil. In forest, strength of radar backscattering is affected by complex parameters. Further study might be considered more various forest stand parameters such as canopy density, stand height, volume, and biomass.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.951-957
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• 2003

The analysis of RF performance requirement conditions on communication system is critical indicator to predict the performance of system. UWB(Ultra Wide Band) system which the standard is not established yet is difficult to derive the precise system performance requirement condition. Also, there are differences between conventional UWB system and multi-band system about RF performance requirement condition. In this thesis, the differences are analyzed and performance requirement conditions of multi-band UWB system are described on the basis of the differences. Throughput, maximum transmit power, and sensitivity of multi-band UWB system is varied with respect to the number of Sub-Bands. In addition, because of Multi-path effect, if PRF(Pulse Repetition Frequency) is changed, the Multi-path link margin is happened to compensate for Multi-path Energy Loss which is contributed by increasing of the Link Margin. According to Multi-path Margin, the variation of the resistance with respect to sensitivity and interference signal is observed and analyzed through the simulation.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.254-257
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• 2003

본 논문에서는 휴대폰에 사용되는 Multi-band 용 helical antenna 의 radiation pattern 을 체적화하기 위한 방법을 제안하고자 하였다. 일반적으로 GSM 휴대폰에 사용되는 안테나는 GSM, DCS 의 dual band 인 경우가 다수이며 추세에 따라 요즘은 PCS 등을 포함한 triple band 의 안테나가 많이 선호되고 있다. 이러한 multi band antenna 의 radiation pattern 에 영향을 미치는 변수로 본 논문에서는 ground 의 length 와 width 그리고 폴더쪽에 사용되는 LCD 의 ground 와 폴더쪽 기구물에 사용된 EMI spray 등의 변화를 통해 pattern 의 변화를 알아보고 이러한 변수를 조절하여 radiation pattern을 최적화하는 방법에 관하여 논하였다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.615-616
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• 2006

Nowadays, the need of multi-mode/multi-band transceiver is rapidly increasing, so we design a direct conversion RF front-end for multi-mode/multi-band receiver that support WCDMA/CDMA2000/WIBRO standard. It consists of variable gain reconfigurable LNA and single input double balanced Mixer and complementary differential LC Oscillator. The circuit is implemented in 0.18 um RF CMOS technology and is suitable for low-cost mode/multi-band.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.110-115
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• 2021

A multi-band, compact, and complex vehicle roof antenna has become important in terms of car exterior design and multi-functions which include Radio, DAB/DMB, SXM, GNSS, Telematics, and V2X. In this paper, we propose a compact multi-band V2X pole-type roof antenna. Using impedance change characteristic, a single pole antenna which has multiband such as radio, DAB/DMB, telematics, and V2X band is proposed. With two patch antennas for GNSS and SXM, the dimension of a multiband roof antenna is 131x63x37mm only.

• Journal of electromagnetic engineering and science
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• v.7 no.4
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• pp.154-160
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• 2007

A reconfigurable multi-band mixer for the SDR system is proposed. The proposed reconfigurable mixer is operated between $850\;MHz{\sim}2\;GHz$, which includes all commercial mobile communication service. Because the varactor diodes are used to select a specific frequency and to adjust the impedance characteristic of the selected frequency band, the proposed reconfigurable mixer can be achieved to similar performance across all of the tuning range. In addition, the designed reconfigurable mixer is applicable for the SDR system since it has a single signal path for the multi-band signals and wide band tuning range.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.44-46
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• 2003

In 1996, Thailand's participation in the Pacific Rim as a part of NASA's Mission to Planet Earth (MTPE) Program, was titled 'AIRSAR Thailand Project'. In this project the Department of Land Development utilized Topographic SAR (TOPSAR) which had multi-frequencies: C band, L band, and P band with multi-polarization: HH, VV, and HV as well as C band VV DEM. Satellite data such as LANDSAT TM was also utilized for optimal use. Results of AIRSAR image processing including data fusion among difference wavelength bands and polarization revealed the quality of AIRSAR that best suit for detection of agricultural land uses. The HH-L band AIRSAR was proven to be useful to distinguish among crop types when combined with appropriate data. The HH, VV, and HV-P band enhanced surface characteristics of swamp forest and wetland. In addition, TOPSAR has its great advantage for identification of salt farms and shrimp ponds.