• Proceedings of the KIEE Conference
• /
• 1990.07a
• /
• pp.447-450
• /
• 1990

Nonlinear protection of overcurrent induced on parallel two-wire transmission line by electromagnetic pulse is analyzed. This algorithm is implemented numerically and simulation result for simple incident pulse and nonlinear type agrees with its analytic solution.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.3
• /
• pp.33-42
• /
• 2002

응용분야가 다양하고 고속 전송 및 노이즈 레벨의 주파수 대역에서 통신을 할 수 있는 UWB(Ultra Wide Band) 기술에 대한 관심이 증폭되고 있다. 울트라 쇼트 펄스파(ultra short pulse)에 정보를 실려 송수신하는 UWB 기술을 근거리 고속 통신이나 휴대용 단말기에 응용하고 저가격의 제품제작을 위하여 저전력 IC 개발은 핵심요소이다. 본 글에서는 UWB IC의 회로 구성 및 동작과 IC 개발업체의 현황을 논한다.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.4
• /
• pp.13-24
• /
• 2002

CDMA 시스템은 성능의 우수성에도 불구하고 신호처리의 복잡성과, 여러 채널의 신호를 동시에 전송시, 채널수가 증가할수록 신호의 PAPR(Peak to Average Power Ratio)가 증가하는 문제점을 갖고 있다. 본 논문에서는 멀티코드 CDMA의 특성과 구조를 유지하면서도 전송신호의 레벨이 항상 일정하여 기존의 TDMA 시스템 구조로도 멀티코드 CDMA 신호를 전송할 수 있는 Binary CDMA 기술에 대해 소개한다. Binary CDMA 기술은 적용 기술별로는 펄스폭 CDMA(PW/CDMA; Pulse Width CDMA), 다위상 CDMA(MP/CDMA; Multi Phase CDMA), 코드선택 CDMA(CS/CDMA; Code Select CDMA)로 구분되며, 사용자간의 상호간섭이 심한 환경에서 무선으로 실시간 멀티미디어를 보내는 소형 휴대형 장비에 적합한 무선 solution을 제공한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2001.11a
• /
• pp.145-149
• /
• 2001

The most of faults in gas insulation of power facilities are caused by partial discharge. Therefore we simulated partial discharge and measured the radiated electromagnetic wave emitted from partial discharge in SF$_{6}$ gas by biconical antenna. This paper describes time delay and electric fields pulse characteristics of radiated electromagnetic waves with distance(1[m], 3[m], 5[m]) between antenna and discharge source.e.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.43 no.4
• /
• pp.687-690
• /
• 1994

This paper presents a method of obtaining transmission network equivalents from the network's response to the pulse excitation signal. Proposed method is base on Prony signal analysis and jtransfer function identification technique. As a result Thevenin-type of discrete-time filter model can be generated. It can reproduce the driving point impedance characteristic of the network.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.385-386
• /
• 2014

본 논문에서는 자심 테슬라 변압기를 이용한 400kV급 소형 고전압 펄스 발생기를 개발하였다. 테슬라 변압기의 효율 및 출력전압 향상을 위해 4분할 적층 원통형 자심 구조를 새롭게 제안 하였다. 제안 된 자심 구조를 적용하여 테슬라 변압기를 제작 한 결과, 최대 출력전압 425kV, 에너지 변환 효율 50%를 확인하였다.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.1169-1171
• /
• 2002

In this paper, RFRPP(Random Frequency Randomized Pulse Position ) PWM for three-phase voltage-controlled inverters is proposed. The LLPWM(Lead-Lag PWM) techinquc is that three switching pulses are located randomly back and forth in each switching interval. But with the restriction of random distribution, the harmonic spectrum cannot be dispersedly and continuously distributed. This paper calculates the duty ratio of the switching pulse firstly. Second, the switching pulses are located randomly in the switching interval. Third, the fixed switching frequency of the space vector modulation is randomly varied. To verify the validity of the proposed technique, simulation study is tried using Matlab/Simulink. When a proposed techniquc is employed, the harmonic spectrum of the inverter output voltagc varies from one cycle to the next and the EMI(Electromagnetic Interference) and resonant vibration are greatly alleviated.

• Proceedings of the Optical Society of Korea Conference
• /
• 2002.07a
• /
• pp.242-243
• /
• 2002

From the dispersion relation of an electromagnetic (EM) wave propagating through plasmas, w$\^$2/ = w$\sub$p/$\^$2/＋c$\^$2/k$\^$2/ the phase velocity (w/k) of the wave is large at high density where w$\sub$p/ is large, and small at low density Therefore, when a laser pulse is located on a downward density gradient of a plasma wave, the phase velocity of the back of the pulse becomes faster than that of the front of the pulse and the pulse wavelength decreases. (omitted)

• Bulletin of the Korean Chemical Society
• /
• v.35 no.3
• /
• pp.891-894
• /
• 2014

The ultrashort electron pulse, laser-emitted from the metal tip apex has been characterized and used as a probing source for a new electron microscope to visualize the morphology of the gold-mesh in the nanometric resolution. As the gap between the tungsten tip and Au-surface is approached within a few nm, the large electromagnetic field enhancement for the incident P-polarized laser pulse with respect to the tip-sample axis is strongly observed. Here, we demonstrate that the time-resolved tip-enhanced electron emission microscope (TEEM) can be implemented on the laboratory table top to give the two-dimensional image, opening lots of challenges and opportunities in the near future.

• Journal of Power Electronics
• /
• v.18 no.3
• /
• pp.902-909
• /
• 2018

This study investigates the influences of different core parameters on the dynamic performances, such as rise time and overshoot, in pulse transformers for the triggering circuit of SCRs. First, a simplified transformer equivalent circuit, which emerges from a standard transformer equivalent circuit, is developed to analyze the step response. Second, the relations between the dynamic performances and the parasitic parameters are calculated by the simplified equivalent circuit. Third, the variations of rise time and overshoot, which are vital to the stability of triggering SCRs, with different core parameters, such as mechanic dimensions and topologies, are comprehensively investigated by analyzing the parasitic parameters. Finally, prototype transformers are fabricated to experimentally validate the analysis. The presented method can practically instruct the design of a pulse transformer for triggering SCRs.