• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.93.3-93
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• 2001

We propose the cascade PID type fuzzy control method for a good performance such as robustness. The one of proposed method, the first stage have two input variables of an error and a derivative error, and one output variable, and the next stage have two input variables of the output of first stage and an integral error, and one output variable, have two stages. The other, the first stage has one input of an error, and one output variable, and the second stage have two input of the output of first stage and a derivative error, and one output variable, and the third stage have two input of the output of the second stage and an integer error, and one output variable ...

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.85-88
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• 2016

90도 하이브리드 커플러에서 두 개의 출력 단자는 일반적으로 90도 위상차의 동일 전력으로 분배된다. 90도 하이브리드 커플러의 두 개의 출력 단자는 입력 단자로부터 전기적 길이가 다르기 때문에 주파수에 따라 서로 다른 출력 기울기를 갖는다. 즉, 동일 전력으로 분배하는 90도 하이브리드 커플러는 중심 주파수에서만 동일한 전력으로 분배되고, 중심 주파수에서 멀어질수록 두 출력 단자에서의 출력 전력은 차이가 크게 발생한다. 본 논문에서는 입력단자와 가까운 거리에 있는 출력단자에 사이에 존재하는 특성임피던스 $35-{\Omega}$의 ${\lambda}/4$ 길이의 선로를 변형시켜 광대역에서 두 개의 출력 단자의 출력 특성이 동일하도록 개선시켰다. 제안된 회로는 ADS(advanced Design System)을 이용하여 살펴보면 두 개의 출력 전력의 차이가 중심주파수 대비 약 20% 대역 이상에서 0.2dB 이내의 값을 가짐을 확인하였다.

• 전기전자학회논문지
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• 제21권2호
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• pp.154-157
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• 2017

본 논문에서는 하나의 입력 전압을 받아 두 개의 출력전압을 가지는 LDO 레귤레이터를 제안한다. 두 개의 출력은 각각의 피드백단을 갖는다. 또한 각각의 피드백 단은 서로 피드백 루프를 공유하며, 서로 피드백 루프를 공유 할 시 서로 미치는 영향을 최소화 하기 위하여 피드백 역할을 하는 PMOS를 추가하여 Load Transient Response를 완화 시켰다. 또한 하나의 바이어스 회로와 하나의 패스 트랜지스터를 사용함으로써 기존 두 개의 출력전압을 얻기 위해 두 개의 LDO 레귤레이터를 사용할 때 대비 면적이 절반으로 줄어들었다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.68-70
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• 2015

4단자 커플러 회로는 입력 단자, 격리 단자와 두 개의 출력 단자로 구성된다. 입력 단자와 격리단자에 신호가 입력하면 입력하는 신호의 세기 및 위상 특성에 의해 두 개의 출력 단자의 출력 신호의 세기와 위상이 결정된다. 본 논문에서는 대표적인 4단자 커플러 회로인 브랜치라인 하이브리드 커플러와 링-하이브리드 커플러를 이용하여 두 개의 입력 단자의 입력 신호 특성에 따른 출력 신호 특성을 분석하였다. 또한, 분석한 신호를 바탕으로 브랜치라인 커플러와 링-하이브리드 커플러의 새로운 이용 방법에 대해 살펴 보았다.

• 전력전자학회논문지
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• 제17권4호
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• pp.306-314
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• 2012

In case of the conventional DC-AC inverter using two DC-DC converters with unipolar output capacitor voltages, for generating the AC output voltage, the output capacitor voltages of its each DC-DC converter must be higher than the DC input voltage. To solve this problem, this paper proposes a single-phase DC-AC inverter using two embedded Z-source converters with bipolar output capacitor voltages. The proposed inverter is composed of two embedded Z-source converters with common DC source and output AC load. The AC output voltage is obtained by the difference of the output capacitor voltages of each converter. Though the output capacitor voltage of converter is relatively low compared to the conventional method, it can be obtained the same AC output voltage. Moreover, by controlling asymmetrically the output capacitor voltage, the AC output voltage of the proposed system is higher than the DC input voltage. To verify the validity of the proposed system, a DSP(TMS320F28335) based single-phase embedded Z-source DC-AC inverter was made and the PSIM simulation was performed under the condition of the DC source 38V. As controlled symmetrically and asymmetrically the output capacitor voltages of each converter, the proposed inverter could produce the AC output voltage with sinusoidal waveform. Particularly, in case of asymmetric control, a higher AC output voltage was obtained. Finally, the efficiency of the proposed system was measured as 95% and 97% respectively in case of symmetric and asymmetric control.

• 전기학회논문지
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• 제60권6호
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• pp.1152-1162
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• 2011

In this paper, a single-phase DC-AC inverter using two embedded Z-source converters is proposed. The proposed inverter is composed of two embedded Z-source converters with common DC source and output AC load. The output AC voltage of the inverter is obtained by the difference of output capacitor voltages of each converter. The output voltage of each converter take shape of the asymmetrical AC waveform centering zero voltage. Therefore, the proposed inverter can generate the same output voltage despite low VA rating L-C elements, compared to the conventional inverter using high DC voltage with AC ripple. To verify the validity of the proposed system, the PSIM simulation was achieved under the condition of rapid increase of DC source (110[V]${\rightarrow}$150[V]) and R-load (50[${\Omega}$]${\rightarrow}$300[${\Omega}$]). For controlling the voltage of the inverter system, the one-cycle controller was adopted. As results, the proposed inverter output the constant AC voltage (220[V]rms/60[Hz]) for all conditions. Also, the R-L load and nonlinear diode load were adopted for the proposed inverter loads, and we could know that the its output voltage characteristics were as good as the pure R-load. Finally, the RMS and THD of output AC voltage were examined for the different loads, input DC voltages and reference voltage signals.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권1호
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• pp.47-53
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• 2006

In this paper, a simple scheme compensating for the effect of dc-link ripple voltages on output voltage of two-leg and three-phase PWM inverters is proposed, where single-phase half-bridge PWM convertor and two-leg inverter are used. The voltage at neutral point of the dc-link is controlled so that the upper-half of do-link voltage is equal to the lower-half voltage in average concept. However, the effect of the do-link ripple voltage results in the inverter output voltage and current distortion. This effect can be eliminated by introducing a compensation voltage in switching time calculation. Also, the inverter dead time should be compensated for sinusoidal output waveform. The proposed scheme has been verified by experimental results which were obtained from the V/F constant operation of the induction motor fed by two-leg inverter.

• Journal of Advanced Marine Engineering and Technology
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• 제39권10호
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• pp.1031-1036
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• 2015

Proportional-integral-derivative (PID) controllers are widely used in industrial sites. Most tuning methods for PID controllers use an empirical and experimental approach; thus, the experience and intuition of a designer greatly affect the tuning of the controller. The representative methods include the closed-loop tuning method of Ziegler-Nichols (Z-N), the C-C tuning method, and the Internal Model Control tuning method. There has been considerable research on the tuning of PID controllers for single-input single-output systems but very little for multi-input multi-output systems. It is more difficult to design PID controllers for multi-input multi-output systems than for single-input single-output systems because there are interactive control loops that affect each other. This paper presents a tuning method for the PID controller for a two-input two-output system. The proposed method uses a real-coded genetic algorithm (RCGA) as an optimization tool, which optimizes the PID controller parameters for minimizing the given objective function. Three types of objective functions are selected for the RCGA, and each PID controller parameter is determined accordingly. The performance of the proposed method is compared with that of the Z-N method, and the validity of the proposed method is examined.

• Journal of Power Electronics
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• 제11권4호
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• pp.499-506
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• 2011

This paper presents an interleaved active-clamping zero-voltage-switching (ZVS) forward-flyback converter without an output choke. The presented topology has two active-clamping circuits with two separated transformers. Because of the interleaved operation of the converter, the output current ripple will be reduced. The proposed converter can approximately share the total load current between the two secondaries. Therefore, the transformer copper loss and the rectifier diodes conduction loss can be decreased. The output capacitor is made of two series capacitors which reduces the peak reverse voltage of the rectifier diodes. The circuit has no output inductor and few semiconductor elements, such that the adopted circuit has a simpler structure, a lower cost and is suitable for high power density applications. A detailed analysis and the design of this new converter are described. A prototype converter has been implemented and experimental results have been recorded with an ac input voltage of 85-135Vrms, an output voltage of 12V and an output current of 16A.

• 전기학회논문지
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• 제58권6호
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• pp.1166-1173
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• 2009

In this paper, we studied on the power amplifier which has the output of the optimal to 100MHz-2GHz band. Optimal output power match was fabricated using the two types; one is the linear tapering and the other is the impedance transformer. In the case of output power match using linear tapering, output power was 35.35dBm at 2GHz and 31.41dBm at 100MHz. The other case of output match using impedance transformer, output power was 34.8dBm at 2GHz and 33.25dBm at 100MHz. Comparison of the results in the two cases, impedance transformer type present the improved results by l.84dB of output power.