• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.459-466
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• 2002

This paper proposes a robust speaker identification algorithm based on the wavelet filter banks and multiple decision-making scheme. Since the proposed speaker identification algorithm has a structure performing the identification algorithm independently for each subband, the noise effect of an subband can be localized. Through this process, we can obtain more robust results for the environmental noises which generally have band limited frequency. In the experiments, the proposed method showed more 15∼60% improvement than the vector quantization method for the various noisy environments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.2
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• pp.53-58
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• 2004

In this paper, the low-phase dual-band VCO, by adding switching circuit with PIN diode at feedback loop of the oscillation part having negative-resistance, is realized. In order to reduce the phase noise of the VCO, PBG structure applied to the ground plane of the resonator. When applying for PBG structure, output power is -9.17㏈m and phase noise is -102㏈c/Hz at 5.25㎓, output power is -5.17㏈m and phase noise is -101㏈c/Hz at 1.8㎓, respectively.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3139-3141
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• 2000

전압제어 트랜스컨덕터를 설계하여 튜닝범 위가 넓은 Gm-C 대역통과 필터를 CMOS 공정으로 설계하였다 Gm-C 필터는 트랜스컨덕터와 캐패시터로 구성된 적분기를 기본으로 구현되고 있다. 따라서 트랜스 컨덕터는 출력단에 캐패시터를 연결하였을 때 이상적인적인 적분기의 특성에 가까울수록 필터의 특성이 좋아지고 PLL 구조의 튜닝이 용이해진다. 본 논문에서는 1:3이상의 범위에서 튜닝이 가능하고 PLL을 기본으로한 자동튜닝과 선형전압 튜닝을 조합하여 주파수 제어회로를 설계하였다.

• Proceedings of the KAIS Fall Conference
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• 2006.11a
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• pp.199-202
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• 2006

RFID는 유비쿼터스 시스템을 실현할 수 있는 기본적 구성 요소이며, 최근 다양한 응용 분야가 개발되어 실제 적용분야가 점차 증가하고 있는 상황이다. RFID 시스템 확산의 가장 큰 문제점은 현실적으로 태그의 가격을 매우 싸게 만들어야 하는 것이고, 이를 해결하기 위하여 많은 업체들이 기술 개발에 전념하고 있다. RFID 시스템 중에서도 가장 큰 관심을 받고 있는 900MHz 대역의 규격인 ISO/IEC 18000-6에서는 새로이 형식 C가 추가되어 기존의 형식 A, B를 포함하여 모두 세 종류의 형식이 제안되었다. 이에 본 논문에서는 형식 C에 대한 규격을 분석하고, 이의 기능 블럭을 VHDL로 구현하였다. 규격에 제안된 것과 동일한 프레임을 구현하고 임의의 데이터를 가정한 후에 데이터 변조 방식으로서 사용되는 PIE와 FM0 변조 방식 등을 구현하고, 이를 송수신 함으로써 변복조가 정확히 구현되었음을 확인하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.9
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• pp.685-697
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• 2017

In this paper, it is presented the result of design and fabrication for C-band solid state high power amplifier unit and components using in search radar. The solid state power amplifier(SSPA) assembly was fabricated using GaN(Gallium Nitride), which is semiconductor device, and the transmit signal output power of the solid state high power amplifier unit is generated by combining the transmit signal power of the solid state power amplifier configured in parallel through a design and fabricated waveguide type transmit signal combine assembler. Designed solid state high power amplifier unit demonstrated C-band 500 MHz bandwidth, maximum 10.5% duty cycle, transmit pulse width from $0.0{\mu}s{\sim}000{\mu}s$, and transmit signal power is 44.98 kW(76.53 dBm).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4C
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• pp.533-540
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• 2004

This paper proposes a new multispectral image data compression algorithm that can efficiently reduce spatial and spectral redundancies by applying classified prediction, a Karhunen-Loeve transform (KLT), and the three-dimensional set partitioning in hierarchical trees (3-D SPIHT) algorithm in the wavelet transform (WT) domain. The classification is performed in the WT domain to exploit the interband classified dependency, while the resulting class information is used for the interband prediction. The residual image data on the prediction errors between the original image data and the predicted image data is decorrelated by a KLT. Finally, the 3-D SPIHT algorithm is used to encode the transformed coefficients listed in a descending order spatially and spectrally as a result of the WT and KLT. Simulation results showed that the reconstructed images after using the proposed algorithm exhibited a better quality and higher compression ratio than those using conventional algorithms.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.5 s.305
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• pp.43-50
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• 2005

This paper describes some IC(integrated circuits) design and implementation techniques of low power multi-band Gm-C bandpass filter for body composition analyzer. Proposed BPF(bandpass filter) can be selected from three bands(20 KHz, 50 KHz, 100 KHz) by control signal. To minimize die area, a simple center frequency tuning scheme is used. And to reduce power consumption, operational transconductance amplifier operated in the sub-threshold region is adopted. The proposed BPF is implemented with 0.35 um 2-poly 3-metal standard CMOS technology Chip area is $626.42um\;{\times}\;475.8um$ and power consumption is 700 nW@100 KHz.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.1
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• pp.80-86
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• 2010

This paper describes the development result of S-band Transmitter of STSAT-3 by satellite research center(SaTReC), KAIST. STSAT-3 has two kinds of communication channels, S- band for Telemetry & Command and X-band for mission payload. S-band Transmiiter(STX) consist of modulator, frequency synthesizer, power amp and DC/DC converter. The modulation scheme of STX is FSK(Frequency Shift Keying). The interface between spacecraft OBC and STX is RS-422. The STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under 1E-5. The Test of STX is completed successfully such as functional Test and environmental(vibration, thermal vacuum) Test.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1314-1317
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• 2014

In this letter, we designed monopole microstrip antenna for WLAN / WiMAX system. The monopole antenna is designed by FR-4 substrate with size is $30mm{\times}40mm$. The proposed antenna is based on a planar monopole design which cover WLAN and WiMAX frequency bands. To obtainthe optimized parameters, we used the simulator, CST's Microwave Studio Program and found the parameters that greatly effect antenna characteristics. Using the obtained parameters, the antenna is designed. Thus the proposed antenna satisfied the -10 dB impedance bandwidth requirement while simultaneously covering the WLAN and WiMAX bands. And characteristics of gain and radiation patterns are obtained for WLAN/WiMAX frequency bands.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8C
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• pp.637-644
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• 2012

In this paper, a new compact power divider is suggested. Instead of the quarter wavelength transmission line(TX-line)s for the branches of the conventional Wilkinson's power divider design method, we use our composite right- and left-handed(CRLH) TX-line zeroth order resonator(ZOR) bandpass filters of one twelfth wavelength and reduce the physical length of the power divider. Besides, the filters in the branches can secure the passband for power-division. To validate the proposed power divider, we take an L-band for millitary satellaite transponder as the test case and the performances of the circuit and full-wave simulation results with the CRLH properties of the structure are shown with the dispersion curve and E-field at the ZOR. The measurement is compared with the simulation results. Also, the size reduction effect by the proposed scheme is addressed