• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.467-472
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• 2007

A modern MEMS resonator is a micro-scale structure operated over a high frequency range. In order to predict its resonant behavior in a design process, High-frequency response analysis (Hi-FRA) is demanded. Algebraic substructuring (AS) is known as a fast numerical technique to construct an eigenspace for FR and frequency sweep (FS) algorithm efficiently solves the frequency response system projected on the eigenspace. However, the existing FS algorithm using AS is developed for low-FRA, say over the range 1Hz-2KHz. In this work, we extend the FS algorithm using AS for FRA over an arbitrary frequency range. Therefore, it can be efficiently applied to systems operated at a high frequency, say over the range 230MHz-250MHz. The success of the proposed method is demonstrated by Hi-FRA of a checkerboard resonator.

• 한국전자통신학회논문지
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• 제9권10호
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• pp.1181-1187
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• 2014

본 논문에서는 차세대 디지털 무선통신시스템에 적용하기 위하여 소프트웨어를 기반으로 한 Polar 송신기를 설계하고 분석하였다. 구현한 Polar 송신기는 CORDIC 알고리즘을 적용하여 I/Q데이터를 입력받아서 진폭과 위상정보를 독립적으로 처리하는 Polar 변환을 하도록 하였으며, 소프트웨어를 이용하여 DDS의 출력신호의 주파수를 Sweep시킬 수 있도록 구성하였다. 구현한 Polar 송신기는 소프트웨어 제어를 통해 DDS의 주파수 제어범위 내에서 1.16 GHz까지 주파수를 제어할 수 있음을 보였다. 향후 이득, 위상, 출력 등 제어 가능한 블록요소들을 제어할 수 있음을 보였으며, 소프트웨어를 이용하여 SDR기반 디지털 무선통신시스템에 적용이 가능함을 보였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2009년도 정기 학술대회
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• pp.135-138
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• 2009

Most of the studies use model order reduction for low frequency (LF) response analysis due to their high computational efficiency. In LF response analysis, one of model order reduction, algebraic substructuring (AS) retains all LF modes when using the modal superposition. However, in mid-frequency (MF) response analysis, the LF modes make very little contribution and also increase the number of retained modes, which leads to loss of computational efficiency. Therefore, MF response analysis should consider low truncated modes to improve the computational efficiency. The current work is focused on improving the computational efficiency using a AS and a frequency sweep algorithm. Finite element simulation for a MEMS resonator array showed that the performance of the presented method is superior to a conventional method.

• Current Optics and Photonics
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• 제1권6호
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• pp.598-603
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• 2017

Traditional three-dimensional (3-D) laser imaging systems are based on real aperture imaging technology, whose resolution decreases as the range increases. In this paper, we develop a novel 3-D imaging technique based on the synthetic aperture technology in which the imaging resolution is significantly improved and does not degrade with the increase of the range. We consider an imaging laser radar (ladar) system using the floodlight transmitting mode and multi-beam receiving mode. High 3-D imaging resolutions are achieved by matched filtering the linear frequency modulated (LFM) signals respectively in range, synthetic aperture along-track, and the real aperture across-track. In this paper, a novel 3-D imaging signal model is given first. Because of the motion during the transmission of a sweep, the Doppler shift induced by the continuous motion is taken into account. And then, a proper algorithm for the 3-D imaging geometry is given. Finally, simulation results validate the effectiveness of the proposed technique.