• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제24권1호
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• pp.103-119
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• 2020

In this work, the hydromagnetic and thermal characteristics of natural convection flow in a vertical parallel plate micro-porous-channel with suction/injection is analytically studied in the presence of Hall current by taking the temperature jump and the velocity slip at the wall into account. The governing equations, exhibiting the physics of the flow formation are displayed and the exact analytical solutions have been obtained for momentum and energy equations under relevant boundary conditions. The impact of distinct admissible parameters such as Hartmann number, Hall current parameter, permeability parameter, suction/injection parameter, fluid wall interaction parameter, Knudsen number and wall-ambient temperature ratio on the flow formation is discussed with the aid of line graphs. In particular, as rarefaction parameter on the micro-porous-channel surfaces increases, the fluid velocity increases and the volume flow rate decreases for injection/suction.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 추계학술대회 논문집
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• pp.142-144
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• 2007

이 논문은 세탁기 모터 구동을 위한 단일 전류 센서 방식에서 3상 전류 복원 방법에 대한 기존 방법에 있어서의 문제점 개선 을 위하여 최소전압 주입 방식 과 Smooth 전압 주입 방식을 제시 하고 인버터에서의 전류 복원 향상을 통한 고조파 와 소음 개선 방법을 제시 하였다. 또한 제시된 방식의 타당성을 검증하기 위한 시뮬레이션 및 실험 결과를 고찰하는 것을 목적으로 한다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.328-331
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• 2009

This paper presents the behaviors of transient and conventional grounding impedances of a 30m counterpoise according to the injection point of lightning impulse currents. As a result, the trend of the conventional grounding impedances measured as a function of risetime of impulse current is similar to the transient grounding impedance of counterpoise. The injection point of impulse current greatly influences on the transient grounding impedance characteristics of counterpoise. The transient grounding impedances strongly depend on the injection point and the rising time of impulse current and the soil characteristics.

• Journal of Power Electronics
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• 제18권2호
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• pp.604-614
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• 2018

This paper proposes a synchronous switching technique for a Vienna rectifier that uses carrier-based pulse width modulation (CB-PWM). A three-phase Vienna rectifier, similar to a three-level T-type converter with three back-to-back switches, is used as a PWM rectifier. Conventional CB-PWM requires six independent gate signals to operate back-to-back switches. When internal switches are operated synchronously, only three independent gate signals are required, which simplifies the construction of gate driver circuits. However, with this method, total harmonic distortion of the input current is higher than that with conventional CB-PWM switching. A reactive current injection technique is proposed to improve current distortion. The performance of the proposed synchronous switching method and the effectiveness of the reactive current injection technique are verified using simulations and experiments performed with a set of Vienna rectifiers rated at 5 kW.

• 전력전자학회논문지
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• 제18권3호
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• pp.225-231
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• 2013

This paper presents an improved signal processing technique in the square-wave-type voltage injection method for IPMSM sensorless drives. Since the sensorless method based on the square-wave voltage injection does not use low-pass filters to get an error signal for estimating rotor position and allows the frequency of the injected voltage signal to be high, the sensorless drive system may achieve an enhanced control bandwidth and reduced acoustic noise. However, this sensorless method still requires low-pass and band-pass filters to extract the fundamental component current and the injected frequency component current from the motor current, respectively. In this paper, these filters are replaced by simple arithmetic operations so that the time delay for estimating the rotor position can be effectively reduced to only one current sampling. Hence, the proposed technique can simplify its whole signal process for the IPMSM sensorless control using the square-wave-type voltage injection. The proposed technique is verified by the experiment on the 800W IPMSM drive system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.346-349
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• 1999

This paper proposes a new series-connected diode rectifier which draws sinusoidal input currents. The proposed rectifier system is configured by adding an auxiliary circuit to the conventional 12-pulse series-connected diode rectifier and employing a current injection technique. A low kVA (0.02Po (PU) ) active current source injects a triangular current results in near sinusoidal input current from the utility with less than 1% THD. The resulting system is suitable for high voltage and high power applications. Experimental results is provided from a 220VA rectifier system.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.271-272
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• 2007

Displacement current $(I_{dis})$ and drain-to-source current $(I_{DS})$ are evaluated using the simultaneous measurements of source $(I_S)$ and drain $(I_D)$ currents during the application of a constant drain voltage and a triangular-wave gate voltage $(V_{GS})$ to top-contact pentacene thin-film transistors.

• 대한전자공학회논문지SD
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• 제37권11호
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• pp.25-35
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• 2000

금속-산화막-반도체 소자의 산화막에 존재하는 느린 준위에 의한 전류반응 특성을 양방향 전류-전압 측정기술을 적용하여 분석하였다. 게이트 바이어스에 따라 나타나는 충전 및 방전시의 순간전류를 유지시간, 지연시간, 전자주입 방향 및 전자주입량, 그리고 전자 주입후 상온 방치시간의 함수로서 조사하였다. 느린 준위의 전하교환에 따른 전류 성분을 게이트 전압에 따라 실리콘 내 캐리어의 이동에 의해 나타나는 변위전류와 분리하여 해석하였다. 충전 및 방전시 나타나는 전하교환 전류는 산화막내 정전하 밀도뿐만 아니라 계면준위 밀도에도 크게 의존이 되며, 본 연구에서는 느린 준위의 전하교환 메카니즘을 제시하였다.

• 대한의용생체공학회:의공학회지
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• 제22권3호
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• pp.303-309
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• 2001

It is well known that the electrical impedance of biological tissues is very sensitive to their temperature. In this paper, we have analyzed the effects of temperature change on the phase of magnetic resonance images obtained with external current injection. It has been found that the local phase in the current injected magnetic resonance image can be changed noticeably when local temperature change appears at a part of the tissue. At the experiments with a 0.3 Tesla MRI system, we observed the local phase changes at the phantom images when the phantom temperature was varied between 25 -45$^{\circ}C$. We think that the current injection MRI technique can be used for in-vivo monitoring of the temperature inside biiological tissues if the relation between the local temperature and phase can be quantified.

• 전자공학회논문지A
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• 제30A권12호
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• pp.77-87
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• 1993

PMOSFETs were studied on the effect of Hot-Carrier induced drain leakage current (Gate-Induced-Drain-Leakage). The result turned out that change in Vgl(drain voltage where 1pA/$\mu$m of drain leadage current flows) was largest in the Channel-Hot-Hole(CHH) injection condition and next was in dynamic stress and was smallest in electron trapping (Igmax) condition under various stress conditions. It was analyzed that if electron trapping occurrs in the overlap region of gate and drain(G/D), it reduces GIDL current due to increment of flat-band voltage(Vfb) and if CHH is injected, interface states(Nit) were generated and it increases GIDL current due to band-to-defect-tunneling(BTDT). Especially, under dynamic stress it was confirmed that increase in GIDL current will be high when electron injection was small and CHH injection was large. Therefore as applying to real circuit, low drain voltage GIDL(BTDT) was enhaced as large as CHH Region under various operating voltage, and it will affect the reliablity of the circuit.