• 조명전기설비학회논문지
• /
• 제24권2호
• /
• pp.9-15
• /
• 2010

접지시스템은 전기설비의 기준 전위점을 확보할 뿐만 아니라 대지에 낮은 저항으로 고장전류나 과도전류를 흐르게 한다. 주파수에 대한 함수로 접지 임피던스는 고장이나 과도전류가 넓은 범위의 주파수 성분을 포함하기 때문에 접지성능을 평가하는데 필요하다. 콘크리트봉은 배전계통에서 널리 쓰이는 접지전극중의 하나이다. 본 논문에서는 콘크리트봉의 접지 임피던스를 주파수 60[Hz]에서 100[kHz] 범위까지 측정하여 등가 접지임피던스 모델을 구하였다. 뇌서지가 유입되었을 때 EDSA 프로그램으로 과도접지임피던스의 수치와 파형을 시뮬레이션 하였다.

• 조명전기설비학회논문지
• /
• 제23권8호
• /
• pp.26-32
• /
• 2009

접지시스템은 전기설비의 기준 전위점을 확보할 뿐만 아니라 대지에 낮은 저항으로 고장전류나 과도전류를 흐르게 한다. 주파수에 대한 함수로 접지 임피던스는 고장이나 과도전류가 넓은 범위의 주파수 성분을 포함하기 때문에 접지성능을 평가하는데 필요하다. 동봉은 배전계통에서 가장 많이 쓰이는 접지전극이다. 본 논문에서는 동봉의 접지 임피던스를 주파수 60[Hz] 에서 100[kHz] 범위까지 측정하여 등가 접지임피던스 모델을 구하였다. 뇌격서지가 유입되었을 때 EDSA 프로그램으로 과도접지임피던스의 수치와 파형을 시뮬레이션 하였다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
• /
• pp.477-480
• /
• 2004

We studied the characteristics of impedance and electromechanical coupling coefficient in ZnO and AIN thin films by using resonance frequency spectrum method. The response peak of impedance decreased with the decrease of thickness of piezoelectrics, the number of mode of response peak increased with the increase of substrate thickness. An error of $k_{t}^{2}$ estimated from input $k_{t}^{2}$ increased as the thickness of piezoelectrics decreased and the thickness of substrate increased. Also, the error was increased in case of a large acoustic impedance of substrate. It was found that the composite resonator operating in optimized condition could be designed through the resonance frequency spectrum analysis of composited resonator consisted of piezoelectric thin film and substrate.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2017년도 추계학술대회
• /
• pp.111-112
• /
• 2017

This paper presents a novel three-port converter for the OnBoard Charger of Electric Vehicles by using an impedance control network. The proposed concept is suitable for charging a main battery and an auxiliary battery of an electric vehicle at the same time due to its power handling capability of the converter without additional switches. The power flow is managed by the phase angle (${\Theta}$) between the ports whereas voltage at each port is controlled by the asymmetric duty cycle and the phase shift (${\Phi}$) between the inverter lags controlled by the impedance control network. The proposed system has a capability of achieving zero voltage switching (ZVS) and zero current switching (ZCS) at all the switches over the wide range of input voltage, output voltage and output power. The feasibility of the proposed system is verified by the PSIM simulation.

• 한국전기전자재료학회논문지
• /
• 제24권1호
• /
• pp.57-63
• /
• 2011

Dielectric Barrier Discharge (DBD) reactor with sinsodual AC type of power supply is very widely adopted for its compact size and effective discharging mechanism to generate high density of ozone radicals. However, at the aspect of design on power supply, its optimal switching conditions and topology is achieved by empirical test. Therefore, throughout this paper, it is proposed a design method of DBD power supply to guarantee a maximum ozone yield rate in accordance with DBD reactor modification and impedance variation when rapid gas discharging in the DBD reactor is proceeded.

• Journal of Electrical Engineering and Technology
• /
• 제11권3호
• /
• pp.585-591
• /
• 2016

DOCR can be used to efficiently increase the reliability and to protect the bi-directional D/L(Distribution Lines). As more DG(Distributed Generation)s attempt to connect the bi-directional D/L, there is an increasing need for studies of how to use DOCR installed in the D/L. This paper investigates the operating principles of DOCR and presents the results an effect of sequence and fault impedance in L-L(Line to Line) fault. An advanced DOCR operating algorithm is proposed to reduce the mal-operation of conventional DOCR. The proposed algorithm is applied to the bi-directional power flow system and shows that it decreases the mal-operation of DOCR through the computer simulation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.1348-1349
• /
• 2008

Grounding impedance depends on the frequency of current flowing into a grounding system. Especially, the lightning gives a broad frequency spectrum from low frequency up to 1 MHz. So the grounding impedance related to high frequency current like lightning should be measured with high frequency source. In this paper, we described the grounding impedances of deeply-driven ground rods of 10 $\sim$ 48 m long with respect to the frequency of injected currents. For the experiments, we used the wideband power amplifier which can produce sinusoidal voltages with the frequency ranges of DC $\sim$ 250 MHz. As a result, the longer the ground rod is, the lower the ground resistance is. However the grounding impedance of deeply-driven ground rod in the range of higher frequency is significantly increased. As a consequence, it is important to evaluate the high frequency performance of grounding systems for lightning protection.

• Journal of Power Electronics
• /
• 제16권1호
• /
• pp.268-276
• /
• 2016

A hybrid sinusoidal-pulse current (HSPC) charging method for the Li-ion batteries in electric vehicle applications is proposed in this paper. The HSPC charging method is based on the Li-ion battery ac-impedance spectrum analysis, while taking into account the high power requirement and system integration. The proposed HSPC method overcomes the power limitation in the sinusoidal ripple current (SRC) charging method. The charger shares the power devices in the motor inverter for hardware cost saving. Phase shifting in multiple pulse currents is employed to generate a high frequency multilevel charging current. Simulation and experimental results show that the proposed HSPC method improves the charger efficiency related to the hardware and the battery energy transfer efficiency.

• 한국진공학회지
• /
• 제18권3호
• /
• pp.176-185
• /
• 2009

ICP source의 성능과 구현 가능성은 impedance와 전기장, 자기장의 공간 분포에 큰 영향을 받는다. ICP source의 impedance는 ICP 안테나와 플라즈마의 impedance에 의해 결정된다. 안테나 설계에 있어서 안테나에 형성되는 고전압을 방지하고 공정 중 급격한 impedance 변화를 방지하기 위해서는 ICP source의 허수 impedance가 $-100\;ohm{\sim}+100\;ohm$의 영역에 존재하는 것이 유리하다. 플라즈마 균일도는 안테나에 흐르는 전류와 전압에 의해 형성되는 전기장 세기와 자기장 세기에 영향을 받는다. 원형 안테나와 대칭성이 개선된 안테나에 대해 전자기 simulation과 플라즈마 밀도의 공간분포를 측정하였으며 안테나 형태에 따른 전자기장과 플라즈마 밀도 분포의 개선을 확인하였다. 반경 방향 균일도를 조절하기 위해서는 일반적으로 지름이 다른 복수개의 안테나를 동심원 상에 배치하는 방법을 사용한다. 각 안테나들을 병렬로 연결한 경우 각각의 안테나의 임피던스에 따른 전류 분배 비율이 상이하며, 분배 비율을 조절하기 위해 코일 또는 capacitor를 연결할 경우 나타나는 현상을 계산하였다.

• 전기학회논문지
• /
• 제59권9호
• /
• pp.1626-1631
• /
• 2010

The characteristics of electric current for the voltaic cell are important for electric power applications. In this paper, an electrical equivalent model consist of three resisters and a capacitance for the Cu/NaCl solution/Zn electrochemical cell is proposed. The capacitance which exists in the Zn electrode/electrolytic interface increased according to Zn electrode area, but cannot affect almost in electric current. Complex impedance plot was used to analysis the interface effect for Zn/electrolyte. This result shows that the interface is similar with the electric transmission line. The short current measurements were conducted to investigate the effects of hydrogen peroxide, the watery sulfuric acid and NaCl aqueous solution. As the hydrogen peroxide increased, the electric current increased because the hydrogen gas being converted with the water. Also electric current increased significantly with increase of the hydrogen ion with the watery sulfuric acid and increased with increase of $Na^+$ ion and $Cl^-$ion in the NaCl electrolyte.