• 대한교통학회지
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• 제13권3호
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• pp.67-86
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• 1995

It requires the detector system which can collect highly reliable traffic data in order to perform the real-time traffic signal control. This study is to decide the optimal shape of inductive loop for the real-time traffic signal control .This loop is located at the stopline in the signalized intersection for DS(Degree of Saturation) control. In order to find out the optimal shape of loop, 6types of experiments were performed . The results of the basic experiments of loops are as follows ; -the optimal number of turns for loop is 3 turns. -the impedance values of the loop detectors are similar to that of NEMA standards -the 1.8${\times}$4.5M loop is excellent for sensitivity in actual detection range of car length comparing to other shape of inductive loops. At the experimental of establishments of the optimal loop shape, it found that 1.8 4.5M loop has the highest values of $\DeltaL$ comparing to other types of loops, It means that the range of Lead-in cable length of this loop. And this loop is highly reliable in occpupancy time. Conclusivley, the 1.8${\times}$4.5M inductive loop is the optimal solution as a stop line loop detector for real -time traffic signal control.

• 조명전기설비학회논문지
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• 제25권10호
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• pp.59-66
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• 2011

In electric power system, the circuit breaker is not operated when the higher voltage then the rated TRV(transient Recovery Voltage) appeared in the circuit breaking, The TRV of a circuit breaker means the characteristics of reignition by the arc between two poles. and is decided by the value of connecting Impedance. In this paper we of carried out many kinds of experiments varying the types of bus, the types of installation, the length of installation between 22.9 [kV] level circuit breaker and MTR in general 154/22.9[kV] system, We also simulated the characteristics of TRV using EMTP-RV program. The suitability of TRV in assessed by Uc, RRRV(Rate of Rise of Recovery Voltage) which are defined by the international guide, IEC62271-100. The values of RRRV gained from the cable-made bus are 590[%] lesser than those from the NSPB-made bus respectively. So the triangled type is more rational in the aspect of TRV.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권1호
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• pp.43-49
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• 2005

The high rate of voltage rise (dv/dt) in motor terminals caused by high-frequency switching and impedance mismatches between inverter and motor are known as the primary causes of irregular voltage distributions and insulation breakdowns on stator windings in IGBT PWM inverter-driven induction motors. In this paper, voltage distributions in the stator windings of an induction motor driven by an IGBT PWM inverter are studied. To analyze the irregular voltages of stator windings, high frequency parameters are derived from the finite element (FE) analysis of stator slots. An equivalent circuit composed of distributed capacitances, inductance, and resistance is derived from these parameters. This equivalent circuit is then used for simulation in order to predict the voltage distributions among the turns and coils. The effects of various rising times in motor terminal voltages and cable lengths on the stator voltage distribution are also presented. For a comparison with simulations, an induction motor with taps in the stator turns was made and driven by a variable-rising time switching surge generator. The test results are shown.

• 한국산학기술학회논문지
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• 제3권1호
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• pp.63-68
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• 2002

본 연구는 산업용 전력계통에서의 전기 품질을 개선하기 위한 고조파 진단 툴의 개발에 대한 것이다. 이 시스템은 계통의 다양한 운전상태에서 시뮬레이션과 계측을 통한 전기품질 분석에 적합하도록 구성하였다. 시뮬레이션은 PTW(Power Tools for Windows)를 이용하였고, 고조파 측정에는 Dranetz사의 PP-4300 장비가 RS-232를 통해 개인용 컴퓨터와 연결되어 시뮬레이션과 실측 데이터를 비교분석 할 수 있게 하였다. 케이블의 영상분 임피던스 등 미진한 입력자료는 수정된 T&D와 BICC를 이용하였고, IEEE표준 데이터가 변압기 입력자료 측정에 적용되었다. 제안된 시스템은 대규모 실제 산업용 수변전 계통에 적용한 결과 고조파 진단의 유연성과 효율성을 입증할수 있었다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권6호
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• pp.253-259
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• 2002

This paper deals with the effects of grounding conductors for metal oxide surge arresters. When surge arresters are improperly installed, the results can cause costly damage of electrical equipments. In particular, the route of surge arrester connection is very important because bends and links of leads increase the impedances to lightning surges and tend to nullify the effectiveness of a grounding conductor. Therefore, there is a need to know how effective installation of lightning surge arresters is made in order to control voltage and to absorb energy at high lightning currents. The effectiveness of a grounding conductor and 18 [㎸] metal oxide distribution line arresters was experimentally investigated under the lightning and oscillatory impulse voltages. Thus, the results are as follows; (1) The induced voltage of a grounding conductor is drastically not affected by length of a connecting line, but it is very sensitive to types of grounding conductor. (2) The coaxial cable having a low characteristic impedance is suitable as a grounding conductor. (3) It is also clear from these results that bonding the metal raceway enclosing the grounding conductor to the grounding electrode is very effective because of skin effect. (4) The induced voltages of grounding conductors for the oscillatory impulse voltages are approximately twice as large as those for the lightning impulse voltages.

• 대한전기학회논문지:전력기술부문A
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• 제55권3호
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• pp.116-122
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• 2006

The underground transmission lines is continuously expanded in power systems. Therefore the fault of underground transmission lines are increased every year because of the complication of systems. However the studies dealing with fault location in the case of the underground transmission lines are rarely reported except for few papers using traveling wave method and calculating underground cable impedance. This paper describes the algorithm using fuzzy system and travelling wave method in the underground transmission line. Fuzzy inference is used for fault discrimination. To organize fuzzy algorithm, it is important to select target data reflecting various underground transmission line transient states. These data are made of voltage and average of RMS value on zero sequence current within one cycle after fault occurrence. Travelling wave based on wavelet transform is used for fault location. In this paper, a variety of underground transmission line transient states are simulated by EMTP/ATPDraw and Matlab. The input which is used to fault location algorithm are Detail 1(D1) coefficients of differential current. D1 coefficients are obtained by wavelet transform. As a result of applying the fuzzy inference and travelling wave based on wavelet transform, fault discrimination is correctly distinguished within 1/2 cycle after fault occurrence and fault location is comparatively correct.

• 전력전자학회논문지
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• 제19권4호
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• pp.357-363
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• 2014

A programmable smart charger compatible to various load conditions is proposed in this paper. Since the proposed smart charger is compatible to various mobile devices having different rated voltage and power, it is convenient for carrying and easy to standardize many kinds of battery chargers. Moreover, since it uses the input impedance and built-in PMIC (Power management IC) of the load system to recognize the connection state and specifications of load system, hardware changes of load system is not only hardly necessary but it also features no addition communication cable and easy implementation. To confirm the validity of the proposed charger, the theoretical analysis and experiment results from a prototype compatible to three load conditions 5V/1A, 5V/2A and 12V/1A are provided.

• 한국정보통신학회논문지
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• 제26권8호
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• pp.1188-1195
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• 2022

6-단자 위상 상관기는 동위상 전력 분배기 한 개와 3-dB 90도 위상차 전력 분배기 세 개로 구성된 회로로 입력 신호의 위상을 판별하는 복조 회로에 주로 사용된다. 본 논문에서는 37.5-Ω 동축선 3개를 이용한 광대역 2:1 임피던스 변환 회로 구조의 동위상 전력 분배기와 Wireline 이용한 3-dB 90도 위상차 전력 분배기를 사용하여 광대역에서 동작하는 6-단자 위상 상관기를 제안하였다. 중심 주파수 1000MHz에서 제작된 제안된 광대역 6-단자 위상 상관기는 640~1270MHz 주파수 범위에서 동위상 전력 분배기 입력 신호에 대한 4개의 출력 단자로의 신호 전달 특성(S_i1)은 세기 -6.5±0.6dB와 위상 오차 ±3.4° 이내, 90도 위상차 전력 분배기 입력 신호에 대한 신호 전달 특성(S_i2)은 세기 -6.1±0.6dB와 위상 오차 ±6.2° 이내, 입력 반사계수(S₁₁ and S₂₂) -14dB 이하의 안정적인 값을 가졌다.

• 한국정보통신학회논문지
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• 제20권6호
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• pp.1049-1056
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• 2016

본 논문에서는 접힌 슬롯이 추가된 소형 이중 대역 슬롯 안테나에 대한 설계 방법을 연구하였다. 제안된 슬롯 안테나는 이중 대역 동작을 위해 직사각형 슬롯에 접힌 슬롯이 추가되었다. 직사각형 슬롯은 내부에 직사각형 급전패치를 두어 동축케이블로 급전한다. 직사각형 슬롯의 위쪽 모서리에 접힌 슬롯이 대칭적으로 추가되면 슬롯의 길이가 증가하여 새로운 공진주파수가 낮은 주파수에서 발생한다. 2.45 GHz WLAN 대역과 5 GHz WLAN 대역을 포함하는 4.50-8.30 GHz 대역에서 동작하는 이중 대역 슬롯 안테나를 FR4 기판 상에 $30mm{\times}30mm$ 크기로 제작하였다. 실험 결과, 입력 반사계수 < -10 dB인 대역이 2.40-2.49 GHz, 4.33-9.85 GHz으로 원하는 이중대역에서 동작하는 것을 확인하였다.

• 한국전자파학회논문지
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• 제20권8호
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• pp.721-728
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• 2009

본 논문에서는 기판 집적 도파관(Substrate Integrated Waveguide: SIW) 기술을 이용한 위성통신용 전력 분배기를 제안하였다. 출력 구형 도파관의 크기를 변화시키지 않고, 가이딩 포스트의 위치를 조절하여 등분 비등분의 전력 분배 비율을 조절하였다. 또한, 방사형 도파관의 기본적인 특성과 입력부, 전력 분배의 과정을 자세히 설명하였다. 방사형 도파관의 신호 여기 방법으로 전류 프로브를 사용하여 동축 케이블로 구현하였으며, 출력부는 마이크로스트립 선로를 천이 구조를 이용하여 SMA 커넥터를 이용하였다. 설계된 4분기 전력 분배기는 등분/비등분으로 동작할 수 있으며, 설계 결과를 시뮬레이션과 제작으로 검증하였다. 등분/비등분 전력 분배기의 측정된 결과는 VSWR 2:1을 기준 대역특이 약 2.1 GHz와 3 GHz이다.