• Transactions on Electrical and Electronic Materials
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• 제17권3호
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• pp.129-133
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• 2016

Theoretical and graphical analysis of pull-in-voltage and figure of merit for a fixed-fixed capacitive Micro Electromechanical Systems (MEMS) switch is presented in this paper. MEMS switch consists of a thin electrode called bridge suspended over a central line and both ends of the bridge are fixed at the ground planes of a coplanar waveguide (CPW) structure. A thin layer of dielectric material is deposited between the bridge and centre conductor to avoid stiction and provide low impedance path between the electrodes. When an actuation voltage is applied between the electrodes, the metal bridge acquires pull in effect as it crosses one third of distance between them. In this study, we describe behavior of pull-in voltage and figure of merit (or capacitance ratio) of capacitive MEMS switch for five different dielectric materials. The effects of dielectric thicknesses are also considered to calculate the values of pull-in-voltage and capacitance ratio. This work shows that a reduced pull-in-voltage with increase in capacitance ratio can be achieved by using dielectric material of high dielectric constant above the central line of CPW.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권9호
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• pp.471-475
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• 2001

ln this paper, a micromachined micromechanical switch is presented. The presented switch is operated in the vertical direction to the substrate by an electrostatic force between two parallel plates. The moving plate is pulled down to connect the bumps of the bias node$(V_{DD}/ or GND)$ to the bumps of the output node when a oltage difference exists between the moving plate and the input plate. The switch was designed to operate at a low switching voltage$(\risingdotseq5V)$ by including a large-area, narrow-gap, parallel plate capacitor A theoretical analysis of the designed switch was performed in order to determine its geometry fitting the desired pull-in voltage and release voltage. The designed switch was fabricated by surface micromachining combined with Ni electroplating. From the experimental results of the fabricated switch, its pull-in voltage came Out to be less than 5V and the measured maximum allowable current was 150mA. The measured average ON-state resistance was about 8$\Omega$, and the OFF-state resistance was too high to be measured with digital multimeter.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권6호
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• pp.647-652
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• 2015

Pull-in voltage model of nano-electro-mechanical system with graphene is investigated for the device optimization. In the pull in voltage model, thickness of graphene layer is assumed to be uniform in vertical and lateral direction. Finite element analysis simulation has verified the feasibility of the suggested model. From the suggested model, pull-in voltage change with graphene thickness and cantilever length can be estimated. Maximum induced stress and graphene thickness have a reciprocal relationship.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.343-349
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• 2005

This paper proposes a novel zero-voltage-switching (ZVS) Push-pull DC-DC Converter for high input voltage and high power applications. This topology utilizes two switches in series to replace one switch in conventional push-pull converter, and two clamping diodes are introduced. The voltage stress of the switches is the input voltage, and the switches can realize ZVS with the use of the leakage inductance of the transformer. Furthermore, secondary full-wave rectifier with a clamping capacitor is used to eliminate the voltage oscillation and spike of the rectifier diodes due to the reverse recovery. Therefore, the electromagnetic interference is reduced effectively. The operation principle of the proposed converter is analyzed theoretically. The output characteristic, ZVS condition and design principle of the clamping capacitor are discussed. Experimental results obtained from a 270V input 2kW prototype with $95.8\%$ high efficiency confirms the design.

• 한국산학기술학회논문지
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• 제15권9호
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• pp.5758-5762
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• 2014

정전기적으로 구동되는 마이크로 소자는 센서 및 엑츄에이터 산업 분야에서 널리 활용되고 있다. 정전기적으로 구동되는 마이크로 소자 구조체는 수 마이크로미터 이하의 전극 사이 간격으로서 정전기적인 부착 현상에 의한 고장이 발생 한다. 본 연구에서는 마이크로 소자의 부착 현상을 개선하기위하여 전극의 길이와 면적을 달리한 마이크로 소자의 구조체를 제작하고, 원자 층 증착방법에 의한 알루미나 코팅 전과 후의 마이크로 소자의 풀인 전압(pull-in voltage)을 측정 비교 분석 하였다. 마이크로 소자의 상부 전극 길이 변화에서는 알루미나 코팅 후에 풀인 전압의 상승이 관찰되었고 전극면적이 클수록 풀인 전압 상승이 관찰되었다. 정전기적으로 구동되는 마이크로 소자의 부착 현상을 개선하기위한 방안으로 본 연구에서 적용된 알루미나 코팅 방법은 효과적인 방법이다.

• 전력전자학회논문지
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• 제11권4호
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• pp.385-394
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• 2006

일반적인 푸시풀 컨버터는 스위치 소자의 전압 스트레스로 인하여 그 사용범위가 제한적이다. 그러나 푸시풀 컨버터는 연료전지와 같이 가변의 저전압에서 고전압 출력을 요하는 전력변환기에 적합한 구조이다. 본 논문에서는 연료전지 시스템에 ZVS-ZCS가 가능한 새로운 전력변환기 구조를 제안한다. 제안된 푸시폴 컨버터의 스위치 소자는 새로운 수동 클램프 회로에 의해 ZVS 또는 ZCS가 이루어진다. 또한 이러한 수동 클램프 회로로 푸시풀 컨버터의 순시과전압 문제가 해결되었다. 또한 두 배의 주파수를 갖는 벅 컨버터의 스위칭 신호가 푸시풀 컨버터의 스위칭 신호에 동기 시킴으로서 전류 형 인덕터와 변압기 권선의 피크 전류가 저감된다. 제안하는 계통 연계형 연료 전지 시스템에 대한 동작을 이론적으로 분석하고 시뮬레이션 및 DSP TMS320F2812 을 이용한 1 [kW]급 시작품의 실험 결과로부터 제안하는 인버터의 타당성을 검증하였다.

• Structural Engineering and Mechanics
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• 제76권5호
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• pp.619-629
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• 2020

In current study, surface/interface effects for pull-in voltage and viscous fluid velocity effects on dimensionless natural frequency (DNF) of fluid-conveying piezoelectric nanosensor (FCPENS) subjected to direct electrostatic voltage DC with nonlinear excitation, harmonic force and also viscoelastic foundation (visco-pasternak medium and structural damping) are investigated using Gurtin-Murdoch surface/interface (GMSIT) theory. For this analysis, Hamilton's principles, the assumed mode method combined with Lagrange-Euler's are used for the governing equations and boundary conditions. The effects of surface/interface parameters of FCPENS such as Lame's constants (λI,S, μI,S), residual stress (τ0I,S), piezoelectric constants (e31psk,e32psk) and mass density (ρI,S) are considered for analysis of dimensionless natural frequency respect to viscous fluid velocity u̅f and pull-in voltage V̅DC.

• 전기전자학회논문지
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• 제24권2호
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• pp.598-603
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• 2020

본 논문에서는 Push-Pull 패스 트랜지스터 구조로 인하여 향상된 Load Transient 특성을 향상시킨 LDO(Low Drop-Out)를 제안하였다. LDO 레귤레이터 내부의 오차증폭기의 출력단과 패스 트랜지스터의 게이트단 사이에 제안된 Push-Pull 회로와 출력단에 Push-Pull 회로를 추가하여 전압 라인에 들어오는 Overshoot, Undershoot를 개선시켜 기존의 LDO 레귤레이터보다 개선된 Load Transient 특성의 델타 피크 전압 값을 갖는다. 제안하는 회로는 Cadence의 Virtuoso, Spectre 시뮬레이션을 이용하여 삼성 0.13um 공정에서 특성을 분석하였다.

• Journal of Power Electronics
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• 제13권4호
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• pp.626-635
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• 2013

An analysis of the junction capacitance in resonant rectifiers which has a significant impact on the operating point of resonance circuits is studied in this paper, where the junction capacitance of the rectifier diode is to decrease the resonant current and output voltage in the circuit when compared with that in an ideal rectifier diode. This can be represented by a simplified series resonant equivalent circuit and a voltage transfer function versus the normalized operating frequency at varied values of the resonant capacitor. A low voltage to high voltage push-pull DC/DC resonant converter was used as a design example. The design procedure is based on the principle of the half bridge class-DE resonant rectifier, which ensures more accurate results. The proposed scheme provides a more systematic and feasible solution than the conventional resonant push-pull DC/DC converter analysis methodology. To increase circuit efficiency, the main switches and the rectifier diodes can be operated under the zero-voltage and zero-current switching conditions, respectively. In order to achieve this objective, the parameters of the DC/DC converter need to be designed properly. The details of the analysis and design of this DC/DC converter's components are described. A prototype was constructed with a 62-88 kHz variable switching frequency, a 12 $V_{DC}$ input voltage, a 380 $V_{DC}$ output voltage, and a rated output power of 150 W. The validity of this approach was confirmed by simulation and experimental results.

• Journal of Power Electronics
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• 제18권4호
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• pp.965-974
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• 2018

A new zero-voltage-switching (ZVS) push-pull pulse-width modulation (PWM) converter is proposed in this paper. The wide ZVS condition for all of the switches is obtained by utilizing the energy stored in the output inductor and magnetizing inductance. As a result, the switching losses can be dramatically reduced. A simple auxiliary circuit including two small diodes and one capacitor is added at the secondary side of a high frequency (HF) transformer to reset the primary current during the circulating stage and to clamp the voltage spike across the rectifier diodes, which enables the use of low-voltage and low-cost diodes to reduce the conducting and reverse recovery losses. In addition, there are no active devices or resistors in the auxiliary circuit, which can be realized easily. A detailed steady operation analysis, characteristics, design considerations, experimental results and a loss breakdown are presented for the proposed converter. A 500 W prototype has been constructed to verify the effectiveness of the proposed concept.