• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1668-1671
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• 2003

A novel dual-frequency microstrip printed-dipole antenna operating at 5 GHz and 10 GHz is presented. This antenna is designed for wireless and mobile communication. The balance step coplanar strip is used to be a transmission line at the center of dipole with matching impedance at 50 ohm. Using the conductor strip align on the other side of antenna and adjust the width of step coplanar strip line to improved input impedance matching. By modification for matching impedance of dual frequency antenna are not affected to the radiation patterns. The Finite Difference Time Domain (FDTD) technique is applying to analyze the basic characteristic properties such as $S_{11}$ , input impedance , VSWR and radiation patterns. And these parameters are discussed. The analyze problem space are $51{\times}197{\times}175$ cells and cell dimension are ${\Delta}x=0.3\;mm$ and ${\Delta}y={\Delta}z=0.15\;mm$.

• 대한전자공학회논문지TC
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• 제44권7호통권361호
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• pp.23-28
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• 2007

본 논문에서는 무선 랜용 이중대역 GaAs FET 저잡음 증폭기를 설계하기 위하여 인덕턴스 소스 피드백을 이용하고 입력 단에는 이중대역 LC 공진회로를 이용하였으며, 출력단에는 Cheyshev 필터의 임피던스 변환 회로를 이용하였다. 이중대역 증폭기의 입출력정합회로 설계에 필요한 기법 및 수식들을 유도하였으며 설계된 증폭기를 제작하여 측정한 결과 시뮬레이션 결과와 유사한 측정치를 얻을 수 있었다.

• 전기전자학회논문지
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• 제22권4호
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• pp.1088-1092
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• 2018

In this paper, we propose a dual-mode frequency tripler using push-push and stacked FET structures. The proposed circuit can operate either in frequency multiplier mode or in amplifier mode. In the frequency multiplier mode, push-push frequency multiplication is achieved by allowing input signals with particular phase shifts. In the amplifier mode, the device operates as a distributed amplifier to obtain high gain. Also both modes were designed using stacked FET structure. The designed circuit showed frequency tripled output power of 9.7 dBm at 2.4 GHz with the input at 800 MHz. On the other hand, in the amplifier mode, the device showed 8.9 dB of gain to generate 19.5 dBm at 800 MHz.

• 한국전자파학회논문지
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• 제17권8호
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• pp.707-712
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• 2006

본 논문에서는 이중 바이어스 조절과 PBG 구조를 이용하여 Doherty 증폭기의 효율을 개 선하였다. PBG 구조를 출력 정합 회로에 구현하였으며, 이중 바이어스 조절을 carrier amplifier에 적용하여 낮은 입력 레벨에서도 Doherty 증폭기의 효율을 개선할 수 있었다. 제안된 구조를 이용한 Doherty 증폭기는 기존의 전력 증폭기에 비해 PAE는 8%, $IMD_3$는 -5 dBc 개선하고, 모든 입력 전력 레벨에서 30% 이상의 고효율을 가질 수 있었다.

• 전기학회논문지
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• 제65권5호
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• pp.831-835
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• 2016

In this paper, a dual-channel feed-forward transimpedance(TIA) array is realized in a standard $0.18-{\mu}m$ CMOS technology which exploits automatic gain control function to provide 40-dB input dynamic range for either detecting targets nearby or sensing imminent danger situations. Compared to the previously reported conventional feed-forward TIA, the proposed automatic-gain-control feed-forward TIA(AFF-TIA) extends the input dynamic range 25 dB wider by employing a 4-level automatic gain control circuit. Measured results demonstrate the linearly varying transimpedance gain of 47 to $72dB{\Omega}$, input dynamic range of 1:100, the bandwidth of $${\geq_-}670MHz$$, the equivalent input referred noise current spectral density of 6.9 pA/${\surd}$HZ, the maximum sensitivity of -26.8 dBm for $10^{-12}BER$, and the power consumption of 27.6 mW from a single 1.8-V supply. The dual-channel chip occupies the area of $1.0{\times}0.73mm^2$ including I/O pads.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.270-273
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• 2000

A new phase shift PWM parallel-input/series-output modularized dual converter is proposed in this paper. This converter is operated with a fixed duty ratio and its output voltage is regulated by phase shift between each module. Since the operating duty ratio of each module is fixed it is sufficient to implement a simple open loop drive circuitry for each module and the cost of total system can be much reduced. The operation of the converter is analyzed in this paper and verified by computer simulation.

• 한국전자파학회논문지
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• 제15권8호
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• pp.788-793
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• 2004

본 논문은 각각 1 W 출력의 5.8 GHz 대역의 무선 랜과 이동통신 서비스 주파수 대역인 1.8 GHz 대역에서 동작하는 이중대역 전력증폭기를 설계 및 제작하였다. 전력증폭기의 입력으로 다중대역 신호가 선택적으로 입력되지 않고 동시에 입력되어질 경우 효과적인 구조로 설계하였다. 입력 단에서 두 신호를 분리하기 위하여 PBG를 이용하여 광대역의 저지 특성을 가지는 Diplexer를 사용하였으며, 전력증폭기의 정합에는 Load-pull 이론을 적용하여 최대 출력을 얻도록 하였다. 전력증폭기의 선형성을 증가시키기 위하여 PBG 구조를 적용하였다. 본 논문은 Load-pull정합부 내에 PBG구조를 삽입하여 전력증폭기가 최대 출력 상태에서 선형성을 개선시켰다. 또한 출력 정합부내에서 PBG 구조의 위치에 따른 선형성 개선의 변화 시뮬레이션을 통해서 검증하였다.

• Journal of electromagnetic engineering and science
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• 제13권2호
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• pp.93-103
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• 2013

This paper presented a novel approach for the design of a tunable dual-band bandpass filter (BPF) with independently tunable passband center frequencies and bandwidths. The newly proposed dual-band filter principally comprised two dual-mode single band filters using common input/output lines. Each single BPF was realized using a varactor-loaded transmission line resonator. To suppress the harmonics over a broad bandwidth, a defected ground structure was used at the input/output feeding lines. From the experimental results, it was found that the proposed filter exhibited the first passband center frequency tunable range from 1.48 to 1.8 GHz with a 3-dB fractional bandwidth (FBW) variation from 5.76% to 8.55%, while the second passband center's frequency tunable range was 2.40 to 2.88 GHz with a 3-dB FBW variation from 8.28% to 12.42%. The measured results of the proposed filters showed a rejection level of 19 dB up to more than 10 times the highest center frequency of the first passband.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권4호
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• pp.739-749
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• 2015

A new conceptual dual-buoy Wave Energy Converter (WEC) for the enhancement of energy extraction efficiency is suggested. Based on actual wave data, the design process for the suggested WEC is conducted in such a way as to ensure that it is suitable in real sea. Actual wave data measured in Korea's East Sea (position: $36.404N^{\circ}$ and $129.274E^{\circ}$) from May 1, 2002 to March 29, 2005 were used as the input wave spectrum for the performance estimation of the dual-buoy WEC. The suggested WEC, a point absorber type, consists of two concentric floating circular cylinders (an inner and a hollow outer buoy). Multiple resonant frequencies in proposed WEC affect the Power Ttake-off (PTO) performance of the WEC. Based on the numerical results, several design strategies are proposed to further enhance the extraction efficiency, including intentional mismatching among the heave natural frequencies of dual buoys, the natural frequency of the internal fluid, and the peak frequency of the input wave spectrum.

• Journal of Welding and Joining
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• 제26권2호
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• pp.85-91
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• 2008

In general, the quality of a welding process tends to vary with depending on the work environment or external disturbances. Hence, in order to achieve the desirable quality of welding, we should have the optimal welding condition that is not significantly affected by these changes in the environment or external disturbances. In this study, we used a dual response surface method in consideration of both the mean output variables and the standard deviation in order to optimize the V-groove arc welding process. The input variables for GMA welding process with the dual response surface are welding voltage, welding current and welding speed. The output variables are the welding quality function using the shape factor of bead geometry. First, we performed welding experiment on the interested area according to the central composite design. From the results obtained, we derived the regression model on the mean and standard deviation between the input and output variables of the welding process and then obtained the dual response surface. Finally, using the grid search method, we obtained the input variables that minimize the object function which led to the optimal V-groove arc welding process.