• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.550-553
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• 2002

A source meter is a basic instrument to perform a measurement of DC characteristic of semiconductor devices. the source meter can be used as variable voltage source, variable current source, voltage meter, or current meter. The accuracy of the low current measurement can be improved with the compensation of leakage current and charge and discharge current. In the low current measurement, the RC time constant is extremely big, so the measurement speed is very low. In this thesis, the analysis of the behavior of the measurement current according to the RC time constant and output capacitance and the method to accelerate the measurement speed.

• Journal of Power Electronics
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• 제10권5호
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• pp.518-527
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• 2010

This paper presents a new technique for directly designing a linear digital controller for a single-phase pulse width modulation (PWM) converter systems, based on closed-loop identification. The design procedure consists of three steps. First, obtain a digital current controller for the inner loop system by using the error space approach, so that the power factor of the supply is close to one. The outer loop is composed of a voltage controller, a current control loop including a current controller, a PWM converter, and a capacitor. Then, all the components, except the voltage controller, are identified by a discrete-time equivalent linear model, using the closed-loop output error (CLOE) method. Based on this equivalent model, a proper digital voltage controller is then directly designed. It is shown through PSim simulations and experimental results that the proposed method is useful for the practical design of PWM converter controllers.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.373-375
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• 2008

Studying for environmentally-friendly and efficient energy source is now actively under way on because problems like environmental pollution and exhaust of natural resources are in issue. Pure Cell which is an alternative energy source has low voltage and high current characteristic, therefore boost up voltage converter and DC-AC converter is required to use as a common power source. In this paper, DC-DC converter which has high efficient and high power density is proposed and verified by experimental result.

• 전자공학회논문지A
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• 제33A권10호
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• pp.139-143
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• 1996

We report on the static and dynamic characteristics of optically modulated resonant tunneling diode oscillator (RTDO) formed in double-barrier quantum-well structure. Under the illumination of Ti:Sapphire laser, the dc current-voltage (I-V) curves of RTDO shifted towared lower voltages. This characteristic was found to odify the series resistance, negtive differential resistance, capacitance, and the inductance of the RTDO. As a result, the resonant frequency of TRDO centered at 5.302 GHz was found to decrease about 20 MHz under the laser illumination. At a constnat bias voltage, the oscillation frequency decreased linearly as the laser power was increased.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1038-1040
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• 1992

Booster is used widely as one of the step-up DC/DC power converter in power conversion process for fuel cell power plant which have the electrical characteristic of the high current density and low cell voltage. In view of control system, booster can be unstable when it is operated in broad operation range because the transfer function of booster has zero in right half plane of s-domain. So for reliable operation, controller must make the system stable in whole working range. In this paper, the two control method such as digital PID control and fuzzy control is studied for booster output voltage regulation in fuel cell plant. The design procedure of PID control and fuzzy control is described. And the experiment of designed controller action is performed in various operation points for controller performance test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.246-248
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• 1994

This paper describes a bidirectional Voltage Source PWM Converter for an elevator. From the study of boost rectifier, the control circuit desisted by full digital DSP technique. The characteristic of control circuit is that implements of space-vector PWM method and has feedback loop of DC side load current which reduce DC voltage flucturation.

• 전력전자학회논문지
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• 제19권5호
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• pp.440-449
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• 2014

This study proposes an LLC series resonant converter with a current doubler using a coupled inductor as a rectification circuit for the secondary side. The current doubler circuit is generally used for a high-voltage input and low-voltage output circuit to obtain high efficiency with small transformer turn ratio. However, an inductive circuit is not generally used in the secondary side of an LLC series resonant converter. If inductive components exist on the secondary side, the resonant characteristics are changed through the secondary inductive circuit. Mathematical analysis shows that the secondary-side current doubler with coupled inductor is not affected by the resonant characteristic of the primary LLC if leakage inductance occurs in the coupled inductor. Results of the analysis are proven by simulation; an experiment is also conducted for the proposed circuit.

• 한국정보통신학회논문지
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• 제16권10호
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• pp.2237-2246
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• 2012

본 논문에서는 구강센서를 소형화하고 제조 원가를 낮추기 위해 구강센서에서 필요로 하는 바이어스 회로를 구강센서 칩 내부에서 만들어주었다. 제안된 DC-DC 변환기 회로는 기준전류 발생기(reference current generator) 회로의 IREF를 이용하여 전압 레귤레이터(voltage regulator)에 필요한 기준전류와 바이어스 전류를 각각 공급해준다. 이들 전류가 각각의 전압 레귤레이 회로에서 해당되는 기준전압을 생성하여 부궤환(negative feedback)에 의해 목표전압을 regulation하게 된다. 그리고 기준전류가 전류 복사비(current mirror ratio)에 의해 mirroring되어 정전류인 IB0/IB1을 공급해주고, VREF 전압을 공급해주도록 설계하였다. $0.18{\mu}m$ X-ray CMOS 이미지 센서 공정을 이용하여 설계된 구강센서의 DC-DC 변환기의 출력 전압의 평균 전압, ${\sigma}$와 $4{\sigma}$는 양호한 측정 결과를 얻었다. 그리고 line-pair pattern 영상은 blurring 없이 높은 해상도 특성을 보였으며, 좋은 구강 영상을 획득하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.289-292
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• 2007

The modular line-connected photovoltaic PCS (power conditioning system) is proposed. The proposed system consists of a step-up DC-DC converter and a full-bridge inverter. A step-up DC-DC converter using a dual series-resonant rectifier circuit and a active-clamp circuit is proposed to achieve a high efficiency and a high input-output voltage ratio efficiently. An IncCond (incremental conductance) MPPT (maximum power point tracking) algorithm that improves MPPT characteristic is used. By control a inverter using a linearized output current controller, a unity power factor is achieved. All algorithms and controllers are implemented on a single-chip microcontroller and the superiority of the proposed algorithms and controllers is proved by experiments.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 추계학술대회 논문집
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• pp.279-285
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• 2007

Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.