• Journal of Power Electronics
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• 제15권1호
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• pp.18-30
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• 2015

This paper focuses on a systematical and in-depth analysis of the reactive power and soft-switching regions of Dual Active Bridge (DAB) converters with dual-phase-shift (DPS) control to achieve high efficiency in a wide operating range. The key features of the DPS operating modes are characterized and verified by analytical calculation and experimental tests. The mathematical expressions of the reactive power are derived and the reductions of the reactive power are illustrated with respect to a wide range of output power and voltage conversion ratios. The ZVS soft-switching boundary of the DPS is presented and one more leg with ZVS capability is achieved compared with the CPS control. With the selection of the optimal operating mode, the optimal phase-shift pair is determined by performance indices, which include the minimum peak or rms inductor current. All of the theoretical analysis and optimizations are verified by experimental tests. The experimental results with the DPS demonstrate the efficiency improvement for different load conditions and voltage conversion ratios.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.699-701
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• 2017

장거리 관측용 카메라의 일반적인 운용방법은 광각에서 표적에 대한 탐지를 하며, 망원으로 표적에 대한 인지/식별을 하게 된다. 탐지/인지거리 성능은 방산용 적외선카메라의 성능을 평가하는 중요한 항목이다. 탐지거리 성능이 증가하려면 카메라의 시야가 좁아져야 하고, 좁은 시야각으로 인하여 표적을 찾게 될 확률이 상대적으로 낮아지게 된다. 본 연구에서는 탐지거리 성능을 유지하면서 넓은 시야각을 제공하여 표적에 대한 탐색을 용이하게 할 수 있는 방안을 검토하였다. 그리고 M&S 및 최적화 설계를 통하여 시야 확장형 적외선카메라를 제작하고 시험한 결과를 정리하였다.

• Journal of Communications and Networks
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• 제6권2호
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• pp.163-172
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• 2004

Ultra Wide Bandwidth (UWB) spread-spectrum techniques will playa key role in short range wireless connectivity supporting high bit rates availability and low power consumption. UWB can be used in the design of wireless local and personal area networks providing advanced integrated multimedia services to nomadic users within hot-spot areas. Thus the assessment of the possible interference caused by UWB devices on already existing narrowband and wideband systems is fundamental to ensure nonconflicting coexistence and, therefore, to guarantee acceptance of UWB technology worldwide. In this paper, we study the coexistence issues between an indoor UWB-based system (hot-spot) and outdoor point to point (PP) links and Fixed Wireless Access (FWA) systems operating in the 3.5 - 5.0 GHz frequency range. We consider a realistic UWB master/slave system architecture and we show through computer simulation, that in all practical cases UWB system can coexist with PP and FWA without causing any dangerous interference.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.1075-1080
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• 2003

Design and fabrication process of a full inorganic electroluminescent microdislay based on aluminum / nanostructured porous silicon reverse biased light emitting Schottky diodes are discussing. Being of a solid state construction. this micro-display is cost-effective, thin and light in weight due to very simple device architecture. Its benefits include also super high resolution, wide viewing angles, fast response time and wide operating temperature range. The advantages of full integration of a LED-array and driving circuitry onto a Si-chip will be also discussed.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권2호
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• pp.152-156
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• 2013

This paper presents a fast-lock dual-loop successive approximation register-controlled duty-cycle corrector (SARDCC) circuit using a mixed (binary+sequential) search algorithm. A wider duty-cycle correction range, higher operating frequency, and higher duty-cycle correction accuracy have been achieved by utilizing the dual-loop architecture and the binary search SAR that achieves the fast duty-cycle correcting property. By transforming the binary search SAR into a sequential search counter after the first DCC lock-in, the proposed dual-loop SARDCC keeps the closed-loop characteristic and tracks variations in process, voltage, and temperature (PVT). The measured duty cycle error is less than ${\pm}0.86%$ for a wide input duty-cycle range of 15-85 % over a wide frequency range of 0.5-2.0 GHz. The proposed dual-loop SARDCC is fabricated in a 0.18-${\mu}m$, 1.8-V CMOS process and occupies an active area of $0.075mm^2$.

• 대한기계학회논문집A
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• 제32권1호
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• pp.1-6
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• 2008

This paper presents muscle-inspired serial digital actuators, achieving the improvement of the range-to-precision and range-to-voltage performance. We propose a weight-balanced design for the serial actuators with serpentine springs using serial arrangement of digital actuators. We have measured the displacement range, precision, and drive voltage at unit and serial actuation of 1Hz. The serial digital actuators produce a full range displacement of $28.44{\pm}0.02{\mu}m$, accumulating the unit displacement of $2.8{\pm}0.5{\mu}m$ at the operating voltage of $4.47{\pm}0.07V$. In addition, the serial digital actuators having the displacement precision of $37.94{\pm}6.26nm$ do not accumulate the precision of the unit actuators, $36.0{\pm}17.7nm$. We experimentally verify that the serial digital actuators achieve the range-to-squared-voltage ratio of $1.423{\mu}m/V^2$ and the range-to-precision ratio of 749.6.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.277-280
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• 2001

The proposed clock generator lowers the operating frequency in a system core though it keeps data bandwidth high because it has a multiphase clocking architecture. Moreover. it has a dual loop which is comprised of an inner analog phase generation loop and outer digital phase control loop. It has both advantages of DLL's wide operating range and DLL's low jitter The proposed design has been demonstrated in terms of the concept and Hspice simulation. All circuits were designed using a 0.25${\mu}{\textrm}{m}$ CMOS process and simulated with 2.5 V power supply.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.375-376
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• 2017

• 센서학회지
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• 제21권6호
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• pp.413-419
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• 2012

A dynamic range extension technique is proposed based on a 3-transistor active pixel sensor (APS) with gate/body-tied p-channel metal oxide semiconductor field effect transistor (PMOSFET)-type photodetector using a feedback structure. The new APS consists of a pseudo 3-transistor APS and an additional gate/body-tied PMOSFET-type photodetector, and to extend the dynamic range, an NMOSFET switch is proposed. An additional detector and an NMOSFET switch are integrated into the APS to provide negative feedback. The proposed APS and pseudo 3-transistor APS were designed and fabricated using a $0.35-{\mu}m$ 2-poly 4-metal standard complementary metal oxide semiconductor (CMOS) process. Afterwards, their optical responses were measured and characterized. Although the proposed pixel size increased in comparison with the pseudo 3-transistor APS, the proposed pixel had a significantly extended dynamic range of 98 dB compared to a pseudo 3-transistor APS, which had a dynamic range of 28 dB. We present a proposed pixel that can be switched between two operating modes depending on the transfer gate voltage. The proposed pixel can be switched between two operating modes depending on the transfer gate voltage: normal mode and WDR mode. We also present an imaging system using the proposed APS.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.957-961
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• 1991

The parameters of electro-hydraulic servo system are closely dependent on the variation of system characteristics. Especially the parameter sensitivity is incleased in the servo system with heavy load and wide operating range. This paper shows the effect of parameter variation and the experimental parameter values of high power servo system.