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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Korean Institute of Electromagnetic Engineering and Science
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Journal DOI :
The Korean Institute of Electromagnetic Engineering and Science
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Volume & Issues
Volume 7, Issue 5 - Dec 1996
Volume 7, Issue 4 - Oct 1996
Volume 7, Issue 3 - Aug 1996
Volume 7, Issue 2 - Jun 1996
Volume 7, Issue 1 - Mar 1996
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Realization of Frequency Occupancy Measurement Function
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 7, issue 4, 1996, Pages 279~287
Frequency occupancy data can provide information on both the actual ratio of usage of individual frequency channels and the average ratio of usage of these frequency bands so that the reserved capacity of the spectrum can be estimated. Such an estimate can be used for the planning of additional spectrum allocations and as a means of assessing the impact of new technologies on spectrum usage. In this paper, we introduce about the frequency occu- pancy measurement system that is developed in Korea. And, we introduce Frequency Occupancy Ratio with a time period and with a area zone by using radio monitoing measurement datas.
Performance Evaluation of Co-channel Digital Radio-relay Systems
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 7, issue 4, 1996, Pages 288~299
The co-channel digital radio-relay system improves effectively the use of radio frequency allocations by transmitting signals separately on both orthogonal allocations, and thereby not only the total transmission capacity of frequency band but also its bandwidth effciency are almost doubled, compared tothe interleaved digital radio-relay system. Therefore, the study on the development and application of the con-channel scheme is of importance, for the efficient use of limited frequency bnad. In this paper, we derived the eqations for calculating fade margin as a function of path length as well as error performance in terms of the outage probability for co-channel digital radio-relay system below 10GHz. And, simulation was given to demonstrate how to apply those equations to the real situation.
Characteristics of the Electric and Magnetic Field Waveforms Radiated by Lightning Discharges
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 7, issue 4, 1996, Pages 300~309
The electric and magnetic fields radiated by lightning discharges are significantly changeable in amplitude and time, one of the topics concerning electromagnetic compatibility of modern electronic systems is the efficient and economic protection against transient voltages caused by not only by direct but also by nearly lightning strokes. In this paper, in order to obtain the detailed informations about lightning electromagnetic impulse waveforms, the electric and magnetic fields radiated by lightning discharges in the summer of 1995 were measured by a fast electric antenna and a loop-type magnetic field sensor, and their charac- teristics were presented and analyzed. The signals of the electric and magnetic fields were re- corded continuously by a transient digitizer having a resolution of 12 bit and a memory capacity of 5000 point and using a sampling time of 200 ns. The electric and magnetic field waveforms associated with lightning return strokes are significantly different with those of intracloud discharges. The magnetic fields radiated by intracloud lightning discharges have essentially the same waveforms as the electric field when the lightning discharhes are at distance of 50 km or more. Also the main frequency components of the electric and magnetic fields radiated by lightning discharges range from a few kHz to several hundred kHz.
Trellis-Coded Modulation with Preswitching Diversity for Correlated Fading Channel
Hahm, Young-Kwon ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 7, issue 4, 1996, Pages 310~319
The existing coders used in the fading channels are designed under the assumption that the ideal interleaver, which removes the fading correlation of the channel, is used. With the non-ideal interleaver of finite size, however, the performance of the coded modulation system degrades rapidly when the fading is very slow. A new method which achieves interleaving effects by switching the transmitter antennas is suggested to improve the performance even in the slow fading. The performance of the new system is analyzed. The results show significant performance improvement in the slow fading and at least no deterioration in the fast fading over the existing systems.
A Verification of the Numerical Energy Conservation Property of the FD-TD(Finite Difference-Time Domain) Method by Using a Plane Wave Analysis
Ihn-Seok Kim ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 7, issue 4, 1996, Pages 320~327
This paper presents that the lossy or amplification property of the Finite Difference-Time Domain(FD-TD) method based on the leap-frog scheme is theoretically verified by using a plane wave analysis. The basic algorithm of the FD-TD method is introduced in order to help understanding the analysis procedure. Since our analysis is formulated by the Von Neumann's approach, the stability inequality is also produced as an another outcome.
Numerical Dispersive Characteristics and Stability Condition of the Multi-Resolution Time Domain(MRTD) Method
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 7, issue 4, 1996, Pages 328~335
The numerical dispersive characteristics and the numerical stability confition of the Multi-Resolution Time-Domain(MRTD) method are calculated. A dispersion analysis of the MRTD schemes including a comparison to Yee's Finite-Difference Time-Domain(FDTD) method is given. The superiority of the MRTD method to the spatial discretization is shown. The required computational memory can be reduced by using the MRTD method. We expect that the MRTD method will be very useful method for numerical modelling of electromagnetics.
A Study on the Analysis and Characteristics of Synchronous Oscillator
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 7, issue 4, 1996, Pages 336~345
The S.O(synchronous osillator) oscillates at its natural frequency without the externa applied signal. But if the external signal is applied, the S.O starts to track the external frequency which can be sinusoidal, pulsed or some other waveform. Thus, the output is synchronized with the wide range of tracking bandwidth to the external frequency. Specifically, the S.O also posses frequency division and multiplication capability. All of these indicate that the S.O can overcome the difficulties of syschronization in coherent digital communication systems. This papers proposed application of DS/SS communication with study on the synchronous properties of S.O.
Design of Super Wide-Band Electromagnetic Wave Absorbers Using Cross-Slotted Ferrite in the Double-Layered Type
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 7, issue 4, 1996, Pages 346~352
A wide-band design method of double layered electromagnetic wave absorbers cross-slotted in the second layer(which has very wide band frequency characteristics) is proposed and discussed. The wide-band electromagnetic wave absorber can be designed under some approximations by the the- oretical model using the equivalent material constants method applied to the second layer. Based on the developed model, wide-band electromagnetic wave absorbers with excellent reflectivity characteristics in the frequency range of 30MHz to 3, 170MHz were designed.
Measurement of Electrophysiological Changes Caused by Electromagnetic Radiation Absorbed in Biobody
Ju-Tae Park ;
The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 7, issue 4, 1996, Pages 353~362
In this paper, SAR distribution is calculated according to the rabbit's head using approximation of its medium three layers model. Our experiment was classified 5 groups dependent on the power intensity of 2,450MHz microwave to measure EEG(Electroencephalograph) of rabbit, which was checked in left frontal lobe before and after irradiation of microwave. In results, mean total power of EEG was slightly decreased and mean composition percentages of
wave were increased after irradiation in observation. It means to decrease of elect- rophysiologic activity and trend of fast wave in brain after irradiation of its microwave. We analyzed the electrophysiological effect of the biobody quantitatively using measured EEG and estimated MPE (Maximum Permissible Exposure).