• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.278-282
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• 2003

본 논문에서는 탭 입력 Interdigital Stripline 형태의 군지연 선형화기를 설계하였다. Even 과 Odd mode에 대해 Pole-Zero Method를 적용하여 선형화기를 최적화하는 방법을 제시하였고, 이를 LTCC 기술을 이용하여 제작하기위해 Tap coupling 과 Via, 1/4파장이하의 결합선로 특성까지 고려한 최적화를 수행하여, 2.14GHz에서 160MHz 대역폭에 ${\pm}0.1nS$의 Group delay Variation을 갖는 4단의 선형화기를 설계하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1428-1436
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• 2000

An adaptive predistorter linearizer suitable for the DSP implementation is proposed. Predistortion is performed by the DSP instead of the analog predistorter. RLS algorithm is employed for the optimization process to minimize the errors between the predistorter and postdistorter output signals. Computer simulation results for our linearizer show good performance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.2
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• pp.75-82
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• 2000

In this Paper, a new type of feedforward linearizer using a delay line which controls the phase characteristics of the correction amplifier block is proposed. The extra delay line provides the control-ability of IM signals so that the IM rejection is accomplished without the conventional pilot tone. The error signal loop consists of several key components such as phase shifter and attenuator, subtractor. These key components are replaced by new designs in order to obtain better linearization characteristics without the pilot tone generator which is indispensable in the conventional linearizer designs. The proposed linearizer was designed at Korean PCS band and combined with 35W HPA manufactured by KMW inc., and tested with two-tone signals separated 0.6MHz apart at the center frequency of 1855MHz. The experimental results show C/l improvement by 16.9 ~ 24.6 dB over 15 dB dynamic range(30 ~45 dBm) which gave IMD of 58.5~63.2 dBc for the designed LPA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.7
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• pp.1102-1109
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• 2001

This paper presents the new architecture of an adaptive predistortion linearizer using the polynomial type predistorter. In the proposed linearizer, most of the processes, including the predistortion, are performed with a digital signal processor(DSP). The recursive least squares(RLS) algorithm is employed for the optimization process to minimize the errors between the predistorter and postdistorter output signals. Simulation results demonstrate that the adjacent channel power ratio(ACPR) is improved by greater than 40 dB at the band edge with linearization. The convergence and reconvergence performance of the linearizer is also satisfactory.

• The Journal of the Korea Contents Association
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• v.2 no.4
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• pp.23-29
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• 2002

This paper suggest the image compression that is needed to process PACS in medical information system. The image decoding method is used Linear-predictor and Lloyd-Max quantizer(quantization) in the Wavelet transform domain. Wavelet Transform Method is processed the multi-resolution by dividing image into 10 sub-bands of 3 levels. Low frequency domain that is sensitive to human visual characteristic is encoded by DPCM which is lossless encoding methods, and Lloyed-Max quantizer, the optimal quantizer for reducing ringing and aliasing in the image of inter sub-band, is used in the remaining high frequency domain of sub-band. The examination verifies that decompressed images are superior by the result that PSNR is 28.53dB on the input image, 512$\times$152 abdominal CT image and Chest image.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.179-182
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• 1999

전력 증폭기의 3차나 5차 비선형성은 인접 통신 채널에 직접적인 영향을 미치므로 선형화 기법을 이용하여 출력단의 혼변조 신호를 감쇄시켜야 한다. 본 논문에서는 전력 증폭기의 입력 신호를 기저대역에서 왜곡시켜 전력 증폭기를 선형화 시키는 디지털 사전 왜곡기를 구현하였다. 측정에 앞서, 모의실험을 통하여 시스템 변수에 따른 선형화기의 성능을 예측하고, 1차원 참조표(look-up table)를 사용한 사전 왜곡기의 측정 결과, 약 9 dB의 ACPR 개선 효과를 얻을 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.53-56
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• 2003

A linear power amplifier is particularly emphasized on the CDMA system using a linear modulation scheme, because IMD which cause adjacent channel interference and co channel Interference is mostly generated in a nonlinear power amplifier. In this paper, a new type of linearization technique proposed. It is presented that balanced MESFET predistortion linearizer added. Experimental result are present for Korea PCS frequency band. The implemented linearizer is applied to a 30dBm class. A power amplifier for simulation performance. Two-tone signals at 1850 MHz and 1851.23 MHz are injected into the main power amplifier. The main power amplifier with a 12.1dB gain and a P1dB of 30 dBm(two-tone) was utlized. The reduction of IMD is around 22dB.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1369-1373
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• 2003

A linear power amplifier is particularly emphasized on the CDMA system using a linear modulation scheme, because IMD which cause adjacent channel interference and co channel interference is mostly generated in a nonlinear power amplifier. In this paper, a new type of linearization technique proposed. It is presented that balanced MESFET Predistortion linearizer added. Experimental result are present for Korea PCS frequency band. The implemented linearizer is applied to a 30㏈m class A power amplifier for simulation performance. Two-tone signals at 1850 MHz and 1851.23 MHz are injected into the main power amplifier. The main power amplifier with a 12.1㏈ gain and a P1㏈ of 30 ㏈m(two-tone) was utilized. The reduction of IMD is around 22㏈.

• Journal of IKEEE
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• v.4 no.2 s.7
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• pp.241-248
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• 2000

A linear power amplifier is particular emphasized on the CDMA system using a linear modulation scheme, because intermodulation distortion which cause adjacent channel interference and co channel interference is mostly generated in a nonlinear power amplifier. In this paper, a new type of linearization technique proposed. It is presented that balanced MESFET predistortion linearizer added. Experimental result are present for Korea PCS(Personal Communication Service) frequency band. The implemented linearizer is applied to a 30dBm class A power amplifier for simulation Performance. The predistortion linearizer improves the 1dB compression point of the HPA about 2dBm, and intermoudulation distortion about 12.5dBc.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.1
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• pp.35-50
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• 2000

본 논문에서는 반복하중을 받는 철근 콘크리트 쉘구조물의 해석을 위한 비선형 유한요소 해법을 제시하였다 유한 요소로서는 충상화기법을 이용한 부재회전강성도를 갖는 4절점 평면 쉘요소가 개발되었다 두께 방향에 대한 철근과 콘크리트의 재료성질을 고려하기 위하여 충상화기법이 도입되었다. 재료적 비선형성에 대해서는 균열콘크리트에 대한 인장, 압축, 전단모델과 콘크리트중에 있는 철근모델을 조합하여 고려하였다. 이에 대한 콘크리트의 균열모델로서는 분산균열모델을 사용하였으며 철근에 대해서는 1축 응력상태로가정하여 등가의 분산 분포된 철근량으로 모델화하였다 구성모델은 재하, 제하 그리고 재재하과정을 포함하여 요소는 반복하중하에서 철근콘크리트 쉘의 거동을 파악할 수 있다 신뢰성 있는 실험결과와 비교를 통하여 본 논문의 해석방법이 반복하중을 받는 철근콘크리트 쉘구조의 비선형 해석에 적합한 방법임을 입증하고자 한다.