• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.39.4-39
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• 2002

This paper presents a design and implementation of a PID feedback control loop for micro gyroscope. The feedback control loop improves the gyroscope performance such as linearity, bandwidth, and bias stability for micro gyroscope which is basically a high-Q system and exhibits a low performance with an open loop control. The designed and implemented feed-back control loop is applied to the SNU-Bosch MEMS gyroscope to demonstrate the improvement with the feedback control loop. The bandwidth is improved to 60Hz from 25Hz of open loop control. The linearity becomes 0.5% from 1%. The bias stability is improved to 0.03 deg/sec from 0.06 deg/sec.

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권4호
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• pp.275-280
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• 2006

We propose Doherty power amplifier structure which can be integrated in Silicon RF ICs. Doherty power amplifiers are widely used in RF transmitters, because of their high Power Added Efficiency (PAE) and good linearity. In this paper, it is proposed that a method to replace the quarter wavelength coupler with IQ up-conversion mixers to achieve 90 degree phase shift, which allows on-chip Doherty amplifier. This idea is implemented and manufactured in CMOS 5 GHz band direct-conversion RF transmitter. We measured a 3dB improvement output RF power and linearity.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.62-66
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• 2006

본 논문은 도허티 증폭기 및 포락선 전치 왜곡기를 이용한 전력 증폭기의 효율 및 선형성 개선에 관한 것이다. 전력 증폭기의 효율을 개선하기 위하여 도허티 증폭기를 제작하여 효율 특성을 개선하였으며, 포락선 전치 왜곡기를 이용하여 도허티 증폭기의 선형성 개선량에 대하여 조사하였다. 제작된 도허티 증폭기는 AB 급으로 동작시킨 전력 증폭기와 비교하여 출력 전력 10W에서 8.5%의 효율 개선 효과를 보였으며, 출력 전력 40W에서 12.6%의 효율 개선 특성을 나타내었다. 포락선 전치 왜곡기를 이용한도 허티 증폭기는 출력 전력 10W에서 7dB의 선 형성 개선 효과를 나타내었다. IMT-2000 주파수 대역에서 WCDMA down-link 4 carrier 신호를 이용하여 출력 전력 10W에서 측정한 결과 AB 급으로 동작하는 전력 증폭기와 비교하여 4.2%의 효율 개선 및 6.3dB의 선형성 개선 효과를 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.464-467
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• 2002

$TiO_{2}-Co_{3}O_{4}$ humidity sensors were fabricated by conventional ceramic process and their humid sensing characteristics were investigated. The sample which was added 10wt% $Co_{3}O_{4}$ and heat-treated $1200^{\circ}C$ showed the highest sensitivity to humidity changes and improved a linearity. As $Co_{3}O_{4}$ content was increasing, the sensor consists a uniform pore distribution and grain in the surface. This was analyzed by SEM photographs.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.211-212
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• 2006

This paper represents a Doherty amplifier with analog predistorter to improve the linearity of the Doherty amplifier while preserving the high efficiency. A $3^{rd}$-order predistorter cancels $5^{th}$-order intermodulation (IM5) as well as $3^{rd}$-order intermodulation (IM3) components by their same phase difference in the predistorter and Doherty amplifier. This is accomplished by independently controlling their phase by using the phase-controlled error generator in the predistorter. For experimental verification, a $3^{rd}$-order predistorter has been implemented and tested in a 180-W Doherty amplifier at the wide-band code division multiple access (WCDMA) band. The measured results show good performance with the predistortion Doherty amplifier.

• 대한디지털의료영상학회논문지
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• 제13권1호
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• pp.27-32
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• 2011

The conventional types of X-ray generators were bulky in physical size and heavy in weight, and the control accuracies of the output voltages were not always satisfactory. The high frequency switching inverter and converter technology on power conversion and control systems have been greatly closed up introducing power semiconductor devices. To decreasing the volume and the weight of high voltage transformer, and to stabilize ripple. In this paper, the newly developed x-ray generator in a low cost using duty modulation PWM inverter. This system verify improved performance by stabilize ripple of X-ray tube voltage and compared the reproducibility, linearity and dose in single phase, three phase and PSU.

• Journal of Multimedia Information System
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• 제8권1호
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• pp.45-56
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• 2021

This document traces the new technologies development based on a deep classical Hill method improvement. Based on the chaos, this improvement begins with the 256 element body construction, which is to replace the classic ring used by all encryption systems. In order to facilitate the application of algebraic operators on the pixels, two substitution tables will be created, the first represents the discrete logarithm, while the second represents the discrete exponential. At the same time, a large invertible matrix whose structure will be explained in detail will be the subject of the advanced classical Hill technique improvement. To eliminate any linearity, this matrix will be accompanied by dynamic vectors to install an affine transformation. The simulation of a large number of images of different sizes and formats checked by our algorithm ensures the robustness of our method.

• 한국항해학회지
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• 제24권5호
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• pp.417-422
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• 2000

The 3rd order intermodulation(IM3) signals affect a great influence on fundamental signal because IM3 can not be rejected by a filter. To solve this problem, in this paper, a predistortion method was applied. The designed predistorter cascaded to 4 W power amplifier and tested with two-tone spreaded 5 MHz. As an experimental result, it was cleary shown that the 3rd order intermodulation distortion characteristics has been improved as much as 17 dB when the output of the power amplifier is 30.67 dB.

• 한국통신학회논문지
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• 제2권1호
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• pp.35-42
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• 1977

低周波增幅을 C級以上의 效率로 實現할 수 있는 스위칭 모우드 增幅器의 性能을 解析하였고 變調器로 使用하기 위한 回路構成과 얻어지는 特性改善에 關하여 考察하였다. 그 結果 變調度 97〔%〕까지의 直線性, 7,200〔Hz〕까지의 平坦한 周波數特性을 確認할 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.89-90
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• 2007

In this paper, we propose Doherty amplifier with proper drain bias line. By $\lambda$/4 microstrip line, IMD is eliminated. Also output power of amplifier is reduced in wanted bandwidth. For linearity improvement, we design drain bias with narrow $\lambda$/4 microstrip line. We observe that gain characteristics improve 1dB and $3^{rd}/5^{th}$ IMD characteristics reduce 5dB/10dB.