• 한국표면공학회지
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• 제43권3호
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• pp.154-158
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• 2010

Numerical analysis is done to investigate the effects of pulse bias on the plasma processing characteristics like ion doping and ion nitriding by using fluid dynamic code with a 2D axi-symmetric model. For 10 mTorr of Ar plasma, -1 kV of pulse bias was simulated. Maximum sheath thickness was around 20 mm based on the electric potential profile. The peak electron temperature was about 20 eV, but did not affect the averaged plasma characteristics of the whole chamber. Maximum ion current density incident on the substrate was 200 $A/m^2$ at the center, but was decreased down to 1/10th at radius 100 mm, giving poor radial uniformity.

• Journal of Power Electronics
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• 제14권5호
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• pp.957-966
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• 2014

Some of DC actuators used in home automation, office automation, medical equipment and automotive systems require a position sensor. In low power applications, the introduction of such a transducer remarkably increases the whole system cost, which justifies the development of sensorless position estimation techniques. The well-known AC motor drive sensorless techniques exploiting the fundamental component of the back electromotive force cannot be used on DC motor drives. In addition, the sophisticated approaches based on current or voltage signal injection cannot be used. Therefore, an effective and inexpensive sensorless position estimation technique suitable for DC motors is presented in this paper. This technique exploits the periodic pulses of the armature current caused by commutation. It is based on a simple pulse counting algorithm, suitable for coping with the rather large variability of the pulse frequency and it leads to the realization of a sensorless position control system for low cost, medium performance systems, like those in the field of automotive applications.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.754-756
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• 2013

최근 전자전(Electronic Warfare)에서는 기존 레이더 신호와는 다른 펄스 내 변조의 특성을 가지고 있는 저피탐확률 (LPI : Low Probability Intercept) 레이더가 도입/운용되고 있는 추세이다. 이러한 LPI 레이더를 탐지하기 위하여 본 논문에서는 펄스 내 변조를 식별하는 방법을 기술한다. 특히 레이더 펄스 내 변조 형태 중, 다양한 주파수 변조 패턴을 가지고 있는 FM(Frequency Modulation) 계열의 변조 형태를 식별하는 방법과 식별에 활용되는 특징인자를 제안하는데 초점을 맞추고 있으며, 이렇게 제안된 식별 방법 및 특징인자는 MathLab을 통해 성능을 검증하였다.

• 비파괴검사학회지
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• 제25권1호
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• pp.15-19
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• 2005

일반적인 와전류 검사는 단일 주파수 또는 매우 협소한 주파수 대역을 가지는 정현적 신호 사용하며, 알루미늄과 같은 도체에서 피로 균열 같은 결함을 검출하는데 사용되고 있다. 이에 반하여 펄스 와전류는 아주 넓은 주파수 대역폭을 가지는 펄스 신호를 사용한다. 이것은 여러 주파수를 동시에 사용하는 다중 주파수 와전류 검사를 한번에 수행할 수 있도록 하며, 일상적인 와전류 검사에 비하여 침투 깊이를 더 깊게 할 수 있다는 장점이 있다. 본 연구에서는 부식 또는 침식 등에 의한 금속 손실을 평가하기 위한 펄스 와전류 장치를 개발하였다. 개발된 장비는 최대 40 V의 구형 펄스를 발생시키는 펄스 발생기, 수신된 신호를 52 dB까지 증폭하는 증폭기, 16 bit 20MHz의 A/D 변환기, 윈도우 프로그램으로 운영되는 산업용 개인 컴퓨터로 구성하였다. 펄스 와전류 탐촉자는 구동 코일 안에 검출 코일을 삽입한 pancake 형태로 설계 제작하였다. 검출 코일의 출력 신호는 구동 코일에 전압을 끊을 때 갑자기 증가하고 신호의 후반부는 시간에 따라 지수적으로 감소하였으며, 감쇠율을 나타내는 지수 값은 알루미늄 두께가 두꺼울수록 증가하였다.

• Journal of Welding and Joining
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• 제17권5호
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• pp.61-68
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• 1999

For the last two decades, waveform control techniques have been successively developed and applied for the inverter welding machines resulting in the substantial reduction of spatter generated in CO₂ welding. One of the constituents commonly involved in those techniques is to delay the instant of current increase to some extent after the initiation of short-circuiting. Although this technique has been known to be quite effective in reducing the spatter generation through the suppression of is instantaneous short circuiting, the delay time necessary for minimum spatter has not been clearly understood. In this study, the control system for varying the delay time was constructed so that the spatter generation rates could be measured over a wide range of delay time, 0.29-2.0 msec. As a result of this study, it was demonstrated that spatter generation rate(SGR) sharply decreased at delay time of 0.6 msec and longer accompanied with the change in characteristics of short circuit mode from the instantaneous short-circuiting(ISC) dominant to normal short-circuiting(NSC) dominant. Another feature that have been found in current waveform of over 0.6msec was the creation of current pulse right after the arc reignition stage. Because of this current pulses weld pool oscillated in wave-like fashion and it looks like to play an important role in developing short circuiting between electrode and weld pool.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.556-558
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• 1994

This paper proposes a new converter that can reduce the harmonics like conventional 12-pulse dual thyrister converters with the input transformers. Both the bridges are controlled with the shifted firing angle and connected through current sharing reactors. Using the center tapped reactor, the DC link current is controlled with the different two values in order to make the input current waveform 12 pulses.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.323-326
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• 1999

For decrease the harmonic current components of the power source, a first method is insert the choke coil that used the choke input type rectifier, the booster chopper circuit and buck chopper circuit. And the several method are studying like as the PWM(Pulse Width Modulation) converter and the active filter type which is used the high frequency switching and the sinusoidal wave formed input current. In this type, there are many problem as a low efficiency, increased the noise, the high leakage current and cost up by the high frequency switching. For improve this problems, the partial resonan method is used on the booster inducter and lossles snubber condenser. This method decreased the distortion factor has lower harmonic components than the hard switching and there is no switching loss by the ZCS(Zero Current Switching) at switch turn-on and the ZVS(Zero Voltage Swithcing) at switch turn-off

• 대한금속재료학회지
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• 제50권2호
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• pp.152-158
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• 2012

The effect of current waveform on Cu filling into TSV (through-silicon via) and the bottom-up ratio of Cu were investigated for three dimensional (3D) Si chip stacking. The TSV was prepared on an Si wafer by DRIE (deep reactive ion etching); and its diameter and depth were 30 and $60{\mu}m$, respectively. $SiO_2$, Ti and Au layers were coated as functional layers on the via wall. The current waveform was varied like a pulse, PPR (periodic pulse reverse) and 3-step PPR. As experimental results, the bottom-up ratio by the pulsed current decreased with increasing current density, and showed a value of 0.38 on average. The bottom-up ratio by the PPR current showed a value of 1.4 at a current density of $-5.85mA/cm^2$, and a value of 0.91 on average. The bottom-up ratio by the 3-step PPR current increased from 1.73 to 5.88 with time. The Cu filling by the 3-step PPR demonstrated a typical bottom-up filling, and gave a sound filling in a short time.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.148-151
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• 1997

Pspice is not offered a library of mechanical factor like DC Motor, Induction Motor which is needed in Power Electronics field. Therefore, Induction Motor was made library by Equibalent circuit in this study. This model is applied in Voltage-Type inverter and is investigated its characteristics. IGBT is tested by two methods of Macro and Micro Modeling as semiconductor. PWM signal is used of pulse signal. Voltage and current, speed was simulated for assurance of model.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.469-471
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• 1999

In this paper, the method of Space-Vector Pulse Width Modulation(SVPWM) with Fuzzy Logic Regulator(FLR) is proposed. In a conventional SVPWM, the procedures of phase transformation and choosing PWM patterns are complex. So, it should be implemented with high performance processor like Digital Signal Processor(DSP). In order to reduce a calculation burden, a proposed system adopts FLR. Using a linguistic contro strategy based on expert knowledge, FLR relieves the processor from a heavy computations. In simulations, the proposed system is validated.