• 전력전자학회논문지
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• 제22권2호
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• pp.102-108
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• 2017

Proper design guides are proposed for a practical dual-active bridge (DAB) converter based on the mathematical model on the steady state. The DAB converter is popular in bidirectional application due to its zero-voltage capability and easy bidirectional operation for seamless control, high efficiency, and performance. Some design considerations are taken to overcome the limitation of the DAB converter. The practical design methodology of power stage is discussed to minimize the conduction and switching losses of the DAB converter. Small-signal model and frequency response are derived and analyzed based on the generalized average method, which considers equivalent series resistance, to improve the dynamics, stability, and reliability with voltage regulation of the practical DAB converter. The design of closed-loop control is discussed by the derived small-signal model to obtain the pertinent gain and phase margin in steady-state operation. Experimental results of a 3.3 kW prototype of DAB converter demonstrate the validity and effectiveness of the proposed methods.

• 대한전자공학회논문지TE
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• 제39권1호
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• pp.16-21
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• 2002

본 논문에서는 TSPC(True Single Phase Clocking) CMOS 회로를 이용하여 출력특성을 향상시킨 고속 PLL을 위한 이중구조 PFD(Phase Frequency Detector)를 제안한다. 넓은 dead zone과 긴 지연시간을 갖고 있는 기존의 3-state PFD는 고속 동작에 사용되는 PLL(Phase-Locked Loop)에서 사용하는 것은 부적합하다. 이러한 3-state PFD의 단점을 해결하기 위하여 다이내믹 CMOS 논리회로로 구현된 다이내믹 PFD는 duty cycle의 변화에 따라 지터 잡음을 발생하는 문제점을 갖는다. 이러한 문제를 해결하기 위하여 TSPC 회로와 이중구조를 갖도록 설계되어 제안된 PFD는 dead zone과 duty cycle의 제한조건을 개선하였고, 지터잡음과 응답특성을 개선하였다. 즉, 이중구조를 갖는 PFD는 상승에지에서 동작하는 P-PFD(Positive edge triggered PFD)와 하강에지에서 동작하는 N-PFD(Negative edge triggered PFD)로 구성하여 이득을 증가시켜 응답특성을 개선한다. 제한된 내용의 입증을 위하여 Hspice 시뮬레이션을 수행하였다. 제안된 PFD는 dead zone이 존재하지 않으며, duty cycle의 변화에도 안정된 결과를 나타내며 응답특성이 우수함을 확인할 수 있었다.

• 한국ITS학회 논문지
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• 제12권1호
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• pp.58-65
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• 2013

본 논문에서는 일반 루프안테나를 개조한 BLA(Branch Loop Antenna)를 소개하고, 휴대 단말기에 적용될 수 있음을 보인다. 브랜치 소자를 사각형 루프안테나에 추가하고, 길이를 조절하여 낮은 공진 주파수를 얻는다. 공진주파수 2.5GHz를 갖는 단일 루프의 경우, 같은 크기의 BLA로 공진을 900MHz대로 낮춘다. 다중 공진은 BLA의 접속위치와 길이로부터 얻는다. 2중 밴드 BLA에 대한 구현 및 측정으로부터, GSM900밴드에서 75MHz의 -10dB 밴드폭, 평균이득 -3.03~-1.46dBi 및 49.73~71.39% 효율을 얻었고, DCS1900밴드에서 90MHz의 -6dB 밴드폭, 평균이득 -8.14~-2.17dBi 및 15.34~60.62% 효율을 얻었다. 또한 H면 무지향 패턴 특성을 보였다. 이들 특성은 휴대 단말기 안테나로 적용될 수 있는 좋은 특성이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.1132-1135
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• 2002

In this paper, we propose a phase-locked loop (PLL) with dual loops in which advantages of both loops can be combined. Frequency-locked loop (FLL) which is composed of two frequency-to-voltage converters (FVC) and an amplifier makes the frequency synchronize very fast and output signal is synchronized in phase with the input reference signal by charge pump PLL. This structure can improve the trade-off between acquisition behavior and locked behavior.

• ETRI Journal
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• 제32권4호
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• pp.610-613
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• 2010

This letter presents the design of a novel multiband USB dongle antenna with a compact ground plane. The radiating patch is composed of a modified meander-line monopole and a shorted loop to generate a dual-broadband resonance. The proposed antenna supports WiBro, Bluetooth, WLAN, WiMAX, and S-DMB services. The total dimensions of the fabricated antenna are 10 mm ${\times}$ 45 mm ${\times}$ 1 mm, the most compact size among multiband USB dongle antennas reported to date. The measured 10 dB reflection loss bandwidths are 20.8% (2.24 GHz to 2.76 GHz) and 20.2% (4.86 GHz to 5.95 GHz). The measured peak gain is 2.97 dBi, and efficiency is higher than 58%. In addition, the radiation pattern approximates an omnidirectional pattern.

• 전력전자학회논문지
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• 제25권3호
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• pp.235-241
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• 2020

In this paper, we propose the bus/bypass synchronization phase lock loop (B-Sync PLL) method using each phase voltage controller of a parallel UPS inverter. The B-Sync PLL included in each phase voltage control system of parallel UPS inverters has the transient response and the phase synchronization error at grid normal or blackout. The validity of this method is verified by simulation and experiment. As a result, the parallel UPS inverters using the proposed method confirmed that the output phase was continuously synchronized when a grid blackout, improving the transient response characteristics for stable load power supply and equal load sharing.

• 한국군사과학기술학회지
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• 제5권1호
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• pp.96-106
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• 2002

Many modern guided weapon systems employ sophisticated target sensors as well as powerful computing systems. Due to such advanced features, they are required to achieve better guidance accuracy, and at the same time other guidance objectives for better weapon effectiveness and survivability. In this paper, we overview some of the technical considerations in such advanced guidance algorithm development, and briefly look at some related research works. More specifically, we discuss impact angle control, time-varying nature of the guidance system, time-to-go estimation, guidance loop stability, effect of autopilot lag and physical limitations in control variables, parasitic paths in guidance loops, etc. We also briefly look at some advanced concepts such as integrated guidance and control loop design, target adaptive guidance, guidance law development based on dual control concept, and terminal evasive maneuver.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.70.1-70
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• 2001

Recently, research of visual control is getting more essential in robotic application, and acquiring 3D informations from the 2D images is becoming more important with development of vision system. For this application, we propose the effective way of controlling stereo vision tracking system for target tracking and calculating distance between target and camera. In this paper we address improved controller using dual-loop visual servo which is more effective compared with using single-loop visual servo for stereo vision tracking system. The speed and the accuracy for realizing a real time tracking are important. However, the vision processing speed is too slow to track object in real time by using only vision feedback data. So we use another feedback data from controller parts which offer state feedback ...

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1289-1294
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• 2003

This paper proposes a novel and efficient intelligent digital redesign technique for a Takagi-Sugeno (TS) fuzzy system. The term of intelligent digital redesign involves converting an existing analog fuzzy-model-based controller into an equivalent digital counterpart in the sense of state matching. In this paper, we suggest the discretization method based on the dual-rate sampling approximation is first proposed, and then attempt to globally match the states of the overall closed-loop TS fuzzy system with the pre-designed analog fuzzy-model-based controller and those with the digitally redesigned fuzzy-model-based controller. To show the feasibility and the effectiveness of the proposed method, a computer simulation is provided.

• 제어로봇시스템학회논문지
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• 제15권3호
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• pp.258-264
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• 2009

This paper presents two control algorithms for the frequency and amplitude of the resonator of a micro sensor. One algorithm excites the resonator at its a priori unknown resonant frequency, and the other algorithm alters the resonator dynamics to place the resonant frequency at a fixed frequency, chosen by the designer. Both algorithms maintain a specified amplitude of oscillations. The control system behavior is analyzed using an averaging method, and a quantitative criterion is provided for the selecting the control gain to achieve stability. Tracking and estimation accuracy of the natural frequency under the presence of measurement noise is also analyzed. The proposed control algorithms are applied to the MEMS dual-mass gyroscope without mechanical connecting beam between two proof-masses. Simulation results show the effectiveness of the proposed control algorithms which guarantee the proof-masses of the gyroscope to move in opposite directions with the same resonant frequency and oscillation amplitude.