직류와 60 Hz 교류가 중첩된 전압에 대한 산화아연 피뢰기 소자의 누설전류 특성

이복희,강성만,박건영,Lee Bok-Hee,Kang Sung-Man,Pak Keon-Young 대한전기학회 2005 전기학회논문지C Vol.54 No.1

This paper presents the characteristics of leakage currents flowing through ZinC Oxide(ZnO) surge arrester blocks under mixed direct and 60 Hz alternating voltages. A mixed voltage, in which an alternating voltage is superimposed upon a direct voltage, appears on the HVDC system network. The mixed direct and alternating voltage generator with a peak open-circuit of 10 kV was designed and fabricated. The leakage currents and V-I curves for the fine and used ZnO surge arrester blocks were measured as a function of the voltage ratio k, where the voltage ratio k is defined as the ratio of the peak of alternating voltage to the peak of the mixed voltages. The resistive component in the leakage current in the low conduction region is significantly increased with increasing the voltage ratio k. The V-I characteristic curves for the mixed voltages lies between the direct and alternating characteristics, and the cross-over phenomenon in the high conduction region was appeared.

고대영어의 어순 연구 - 장벽개념에 의한 ECP 의 선행사지배를 중심으로 -

이복희 한국영어영문학회 1991 영어 영문학 Vol.37 No.3

가정용 전기기구의 효과적인 뇌서지 보호기법

이복희,강성만,엄주홍,이수봉,길형준,구본완,안창환 대한전기학회 2004 전기학회논문지C Vol.53 No.3(C)

This paper deals with the effective protection method for the household electric appliances against lightning surges invading from the power lines. Direct or induced lightning is the main cause of the breakdown of household electric appliance. The most effective protection method is to install SPDs(surge protective devices) at household electric appliances. If SPDs were not installed at most household electric appliances, it is necessary to install SPDs on the mains. Therefore the propagation aspect and protection methods of lighting surges coming into household electric appliances through the mains was experimentally investigated. The in actual-sized test circuits results of protection method for 8 household electric appliances including computer monitors and TV set could be summarized as follows: The breakdown characteristics of household electric appliances from lightning surges were significantly changed with the their input impedance. Namely, the types of input impedance are classified into infinite, resistive or inductive impedances. Especially, the monitor for computer with inductive input impedance from lightning surges was relatively weak against lightning surges. It was confirmed that the self inductance of branch circuits on the mains have protection effect for household electric appliances against lightning surges invading from the power lines. Also the varistors installed at cabinet panel or circuit-breaker were more effective than multi-tap outlet with varistors. When installed varistors in cabinet panel and multi-tap outlet together, the surge protection effect is much more excellent in technical and economical aspects.

봉상접지전극의 접지임피던스의 주파수의존성의 분석

이복희,엄주홍 대한전기학회 2004 전기학회논문지C Vol.53 No.8(C)

This paper presents a systematic approach of measurement, modeling and analysis of grounding system impedance in the field of lightning protection system and intelligent power equipments. The measurement and analysis system of ground impedance is based on a computer aided technique. The magnitude and phase of ground impedance were determined by the novel measurement and analysis using the revised fall-of-potential method. The ground impedances of the ground rod of 50 m long are considerably dependent on the frequency. The ground impedance is mainly resistive in the frequency range of 3-20 kHz. At higher frequencies, the reactive components of the ground impedances are no longer negligible and the inductance of the ground rod was found to be the core factor deciding the ground impedance. Although the steady-state ground resistance of the ground rod of 50 m was less than that of the ground rod of 10 m, the ground impedances of the ground rod of 50 m over the frequency range of more than 60 kHz were much greater than those of the ground rod of 10 m. Furthermore, the equivalent circuit model based on the measured data was proposed, and the calculated results were in approximately agreement with the measured data.

Ranking Forward-Looking Centers and Discourse structure

이복희 한국영미어문학회 2002 영미어문학 Vol.- No.66

On the Integration of the Centering Algorithm with Models of Global Discourse Structure

이복희 한국영미어문학회 2004 영미어문학 Vol.- No.73

This paper discusses the searching mechanism of the antecedent of (overt and null) pronouns in English and Korean. Since centering is underspecified with respect to its interaction to global discourse structure, it is difficult to test centering on extended discourses. Extended discourses are likely to consist of multiple segments, but any claim of the theory cannot be tested on two utterances that span a discourse segment boundary. In this paper, I argue that the restriction of centering to operate within a discourse segment poses many problems for centering theory. They can be eliminated by abandoning this restriction, and by integrating centering with Grosz and Sidner's (1986) stack model and the cache model of attentional state proposed in Walker (1996, 1998).

비선형 소자 및 서지억제회로의 Pspice 시뮬레이션

이복희,공영은,최원규,전덕규,Lee, Bok-Hui,Gong, Yeong-Eun,Choe, Won-Gyu,Jeon, Deok-Gyu 대한전기학회 2000 전기학회논문지C Vol.54 No.12

This paper presents Pspice modeling methods for spark gaps and ZnO varistors and describes the application for the two-stage surge suppression circuit which was composed of the nonlinear components. The simulation modelings of nonlinear components were conducted on the basis of the voltage and current curves measured by the impulse current with the time-to-crest of $1~50 \mus$ and the impulse voltage with the rate of the time-to-crest of 10, 100 and 1000 V/\mus$</TEx>. The firing voltages of the spark gap increased with increasing the rate of the time-to-crest of impulse voltage and the measured data were in good agreement with the simulated data. The I-V curves of the ZnO varistor were measured by applying the impulse currents of which time-to-crests range from 1 to $50 \mus$ and peak amplitudes from 10 A to 2 kA. The simulation modeling was based on the I-V curves replotted by taking away the inductive effects of the test circuit and leads. The meximum difference between the measured and calculated data was of the order of 3%. Also the two-stage surge suppression circuit made of the spark gap and the ZnO varistor was investigated with the impulse voltage of $10/1000\mus$$mutextrm{s}$ wave shape. The overall agreement between the theoretical and experimental results seems to be acceptable. As a consequence, it was known that the proposed simulation techniques could effectively be used to design the surge suppression circuits combined with nonlinear components.

계단상 리더에 의해서 방사된 귀환뇌격 직전의 전장과 자장 파형의 특성

이복희,이동문,정동철,장근철,이승칠,정광희 대한전기학회 2003 전기학회논문지C Vol.53 No.6

In this paper statistics on the radiation field waveforms produced by stepped leaders just prior to lightning return strokes were described. As a parameter of stepped leader pulse characteristics, the time interval between the final leader pulse and return stroke peak, the pause time between stepped leaders, the ratio of the final leader peak to the return stroke peak and the stepped leader pulse width at half maximum were examined. The average time intervals between the final leader pulse and return stroke peak were about 16.2 and 14.8$mutextrm{s}$ for the positive and negative polarities, respectively. When the stepped leader approaches closely to ground, the time interval between leader steps was decreased and the mean value was about 17$mutextrm{s}$, and the present results were in reasonable agreement with the data observed in Florida and Japan. The large fraction of the ratios of the final stepped leader pulse to the lightning return stroke peak were distributed over the range from 5 to 35% and in average the ratio of the final leader pulse to the return stroke peak was 17.4$\pm$11.9% for the positive and 18.5$\pm$9.4% for the negative electric field waveforms. In addition, the mean pulse widths at half maximum of the stepped leaders are 1.4Us with a standard deviation of 0.9 for the positive Polarity and 2.2us with a standard deviation of 1.2 for the negative polarity, respectively.

직류와 60 Hz 교류가 중첩된 전압에 대한 산화아연 피뢰기 소자의 누설전류 특성

이복희,강성만,박건영 대한전기학회 2005 전기학회논문지C Vol.54 No.1(C)

This paper presents the characteristics of leakage currents flowing through ZinC Oxide(ZnO) surge arrester blocks under mixed direct and 60 ㎐ alternating voltages. A mixed voltage, in which an alternating voltage is superimposed upon a direct voltage, appears on the HVDC system network. The mixed direct and alternating voltage generator with a peak open-circuit of 10 ㎸ was designed and fabricated. The leakage currents and V-I curves for the fine and used ZnO surge arrester blocks were measured as a function of the voltage ratio k, where the voltage ratio k is defined as the ratio of the peak of alternating voltage to the peak of the mixed voltages. The resistive component in the leakage current in the low conduction region is significantly increased with increasing the voltage ratio k. The V-I characteristic curves for the mixed voltages lies between the direct and alternating characteristics, and the cross-over phenomenon in the high conduction region was appeared.

운방전에 의해 발생되는 자장의 계측과 통계적 분석

이복희,길형준,조성철,심응보,우정욱 대한전기학회 2005 전기학회논문지C Vol.54 No.6(C)

In this work, to obtain the detailed information about lightning electromagnetic field waveforms, the LabVIEW based-measurement system of time-changing magnetic fields was designed and constructed. The frequency bandwidth of the magnetic field measuring system ranges from 300 [Hz] to 1 [MHz], and the response sensitivity is 2.78 [mV/nT]. Data acquisition system with the resolution of 12 bits and memory capacity of 32 [Mbyte] was triggered by the magnetic field to be measured. The properties and parameters of the magnetic fields produced by cloud discharges were statistically investigated. The magnetic field waveforms radiated from cloud lightning discharges tend to be bipolar, with two or more narrow and several pulses superimposed on the initial front part. The recording length of the magnetic field measurement system is about 10 [ms]. The mean duration of cloud discharges is 1.3 [ms], and the number of outburst pulses for the period is 8 in average. The front times of the magnetic fields are 6.15 [㎲] in average. The the zero-to-zero crossing times that is the initial half-cycle duration is widely dispersed and the mean value is 9.61 [㎲], and the mean value of percentage depth of dip to opposite polarity is 41.1 [%].