• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.766-776
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• 2015

It is well known that series arc faults in Low Voltage DC (LVDC) distribution system occur at unintended points of discontinuity within an electrical circuit. These faults can make circuit breakers not respond timely due to low fault current. It, therefore, is needed to detect the series fault for protecting circuits from electrical fires. This paper proposes a novel scheme to detect the series arc fault using Wavelet Singular Value Decomposition (WSVD) and state diagram. In this paper, the fault detector developed is designed by using three criterion factors based on the RMS value of Singular value of Approximation (SA), Sum of the absolute value of Detail (SD), and state diagram. LVDC distribution system including AC/DC and DC/DC converter is modeled to verify the proposed scheme using ElectroMagnetic Transient Program (EMTP) software. EMTP/MODELS is also utilized to implement the series arc model and WSVD. Simulation results according to various conditions clearly show the effectiveness of the proposed scheme.

• 조명전기설비학회논문지
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• 제28권8호
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• pp.62-68
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• 2014

The series connection type superconducting fault current limiter (SFCL) with added third winding, which was magnetically coupled in one iron core, was proposed. The proposed SFCL was expected to be more improved by just adding third winding into the conventional series connection type SFCL with two coils. To analyze the contribution of the third winding for the current limiting and the recovery characteristics of the SFCL, the short-circuit tests for the series connection type SFCL with the added third winding were performed together with the analysis on its electrical equivalent circuit. From the comparative analysis on the amplitude of the limited fault current and the power burden of the high-TC superconducting (HTSC) element comprising this SFCL, the improved current limiting and recovery characteristics of the series connection type SFCL using the third winding could be confirmed.

• 조명전기설비학회논문지
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• 제27권3호
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• pp.16-25
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• 2013

Now it's a trend to install a series of white fluorescent light and orange high pressure sodium lamps because tunnel lighting should be opaque to the safety of drivers from soot, dust, humidity, and fog. Also fluorescent lighting is replaced to LED due to the fact that it improves amenity and object recognition and LED lighting has gradually been improved its nature. In this paper, we have implemented the circuits of the yellow series of high-pressure sodium lamps and white series of LED lights at one board to improve the transparency and recognition of objects. It is possible for inductive high-pressure sodium lamps and the capacitive LED drivers to circuit without power factor compensation. Two circuit parts share only a small number of parts, so low cost LED drivers compared to conventional ones are possible. Therefore, the implementation of the hybrid lighting with high-pressure sodium lamps and LED lights that can be driven at the same time by one driving circuit is possible. The LED capacitive power factor was 0.91 while individually implemented the sodium lamp power factor was 0.98. It shows not only the 2% improvement of hybrid forms but also the efficiency and THD.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1100-1103
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• 1992

Two different resonance inverters used as fluorescent lamp ballast are based on the self oscillation at the series resonance of the circuit components. Each circuit is simulated on a computer in order to explain its function and the variation of the circuit variables for each of the circuit elements. Experimental results have bean carried out on the unsymmetrical scheme to indicate the voltage and current of the fluorescent lamp operation at the high frequency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1158-1160
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• 1992

A new dc/ac soft switched PWM convert having a dc-link commutation circuit is proposed. The commutation circuit implemented by utilizing a series resonant circuit while preparing for zero voltage switching of primary inverter. The converter provides both variable pulse width and position which is fundamentally different than converters. In this paper, the operating principles, design and control considerations analysis of a such a soft switched converter is analyzed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.51-53
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• 2018

This paper describes the design and implementation of a circuit consisting of a simmer power supply unit and a series trigger unit that can be applicable to xenon lamp driving. An LCC resonant converter based on the continuous conduction mode (CCM) is applied to the simmer circuit and by using the current output control it is possible to maintain the ionization of the lamp which has the negative resistance load characteristic. At the same time, in order to generate a high voltage, a series trigger circuit which has a number of capacitors and diodes is designed. The generated high trigger output voltage could ionize the xenon gas. This paper explains the configuration and features of the integrated circuit system, and verifies the proposed design and stable operation of the xenon lamp. The experimental and simulation results show the not only rationality but also stability of the proposed circuit.

• 한국전자파학회논문지
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• 제15권10호
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• pp.1005-1010
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• 2004

슬롯 결한 마이크로스트립라인-도파관 천이기에 대해 간략하지만 정확한 등가 회로 모델을 추출하기 위한 해석 방법을 제안한다. 이 등가회로는 이상적 변압기, 마이크로스트립 개방 스터브, 그리고 슬롯 중심에서 도파관 쪽과 급전선 쪽 반평면으로 바라보는 각각의 어드미턴스들로 구성된다. 관련된 회로 변수 값들은 가역 정리 (Reciprocity theorem), 푸리에 변환과 푸리에 급수(Fourier transform and series), 복소 전력 개념(Complex power concept), 파스발 정리(Parceval's theorem), 그리고 스펙트럼 영역 이미턴스 접근법(Spectral-domain immittance approach)에 의해 계산된다. 계산된 산란계수 값을 측정된 값과 비교하였으며 이들 사이의 상당한 일치도는 제안된 등가회로 모델의 간편성과 정확성을 뒷받침한다.

• 전기학회논문지
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• 제58권8호
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• pp.1644-1650
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• 2009

An improved guarding circuit is applied to a transconductance driven-right-leg circuit to decrease common-mode current at measurement electrodes due to power-line interference. After showing conventional guarding circuit is instable due to gain-peaking when used with a transconductance DRL circuit, the effect of the proposed guarding circuit modified to suppress the gain-peaking by inserting a series resistor between shields and a shield driver was analyzed. It is shown that, besides stability, the proposed guarding circuit provides two other advantages: 1) The gain of the shield driver can be set to be unit nominally. 2) The loop gain of the transconductance DRL loop can be increased due to pole-zero canceling. The proposed circuit was implemented and the advantages were confirmed.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 추계종합학술대회
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• pp.190-195
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• 2000

본 논문에서는 IMT-2000(International Mobile Telecommunication-2000) 휴대용 단말기 수신 주파수인 2.13 - 2.16 GHz 대역의 저잡음 중폭기(LNA ; Low Noise Amplifier)를 직렬 피드백과 저항결합 회로룰 이용하여 설계.구현하였다. 소스 리드에에 부가된 직렬 피드백은 중폭기의 저잡음 특성을 유지하면서 동시에 입력 반사계수를 작게 하고, 또한 대역내의 안정성을 향상시키는 역할을 하였다. 사용된 저항 결합회로는 저주파 영역의 신호를 정합 회로내의 저항을 통해 소모시킴으로써 저잡음 중폭기의 설계시 입력단 정함에 용이하였다. 저잡음 중폭기의 설계.제작에서 저잡음 증폭단에는 HP사의 GaAs FET인 ATF-10136을, 이득 증폭단에는 Mini-Circuit사의 내부 정합된 MMIC인 VNA-25를 사용하였다. 전원회로는 자기 바이어스(Self-bias) 회로를 사용하였고, 유전율 3.5인 테프론 기판 상에 장착하였다. 이렇게 제작된 저잡음 증폭기는 대역 내에서 30 dB 이상의 이득과 0.7 dB 이하의 잡음지수, $P_{ldB}$ 17 dB 이상, 그리고 입.출력 정재파비가 1.5 이하인 특성을 나타내었다.다.

• 전력전자학회논문지
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• 제3권4호
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• pp.307-314
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• 1998

근접부하의 동작주파수의 차이에 의해 발생하는 간섭가청잡음을 제거하기 위해서 다부하를 갖는 유도가열기를 위한 새로운 고역률 이중 하프브릿지 직렬공진 인버터를 제안한다. 이 회로는 하나의 인버터로 두 개의 유도가열요소를 독립적으로 전대역 출력제어를 할 수 있고 영전압 스위칭 특성 때문에 최소 스위칭 손실을 갖는다. 모드분석을 통해서 제안된 회로의 동작을 설명할 것이다. 요구되는 냉각능력을 평가하기 위해서 몇 개의 손실식을 유도함으로써 손실분석을 행하였다. 역률제어기능을 갖고 시스템의 크기를 축소하기 위해서 적절한 설계가이드를 제시하였다. 이렇게 설계된 값들을 사용하여 각 유도가열요소가 2.8kW 전력소모를 갖는 proto-type 회로를 구성하고 제안된 회로의 동작을 확인하기 위해서 실험을 행하였다.