• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.797-803
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• 2002

In this paper we derive the probability density function of the phase error of the received signal over Rician fading channel and verify its propriety as the probability density function using the zeroth moment. In general, for the error probability over fading channel we compute the error probability in the first place when it is only AWGN, and then we get the final result by averaging the first result and the probability density function of the corresponding fading channel. In this paper, however, we compute the error probability by double integration after the probability density function over fading channel is computed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.511-521
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• 2007

In this paper, we designed and fabricated a Ka-band synthesizer module. In addition, the systematic layout procedure and the test procedure were presented for the construction of compact synthesizer. To implement the Ka-band synthesizer, X-band VCO is employed as VCO and its frequency was multiplied by 3 with frequency tripler. The fabricated frequency synthesizer shows a frequency tuning range of 500 MHz, output power of about 14 dBm, and a phase noise of -96.17 dBc/Hz at the 100 kHz offset frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.815-821
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• 2012

A CW Doppler radar can measure radial velocity of an object. It detects a Doppler frequency shift that is proportioned to radial velocity of a moving object. To detect a Doppler frequency shift, FFT(Fast Fourier Transform) is conducted. In this process, the time domain received signal is transformed to a frequency domain. A number of FFT affects not only the time resolution but also signal to noise ratio of received signal. So finally it is related with a radial velocity accuracy. Therefore in this paper, it is described the relation of time resolution and the radial velocity accuracy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.4
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• pp.255-260
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• 2018

In recent years, increasing electricity use has led to considerable interest in green energy. In order to effectively supply, cut off, and operate an electric power system, many electric power facilities such as gas insulation switch (GIS), cable, and large substation facilities with higher densities are being developed to meet demand. However, because of the increased use of aging electric power facilities, safety problems are emerging. Electromagnetic wave and leakage current detection are mainly used as sensing methods to detect live-line partial discharges. Although electromagnetic sensors are excellent at providing an initial diagnosis and very reliable, it is difficult to precisely determine the fault point, while leakage current sensors require a connection to the ground line and are very vulnerable to line noise. The partial discharge characteristic in particular is accompanied by statistical irregularity, and it has been reported that proper statistical processing of data is very important. Therefore, in this paper, we present the results of analyzing ${\Phi}-q-n$ cluster distributions of partial discharge characteristics by using K-means clustering to develop an expert partial discharge diagnosis system generated in a GIS facility.

• Journal of Satellite, Information and Communications
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• v.9 no.4
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• pp.42-46
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• 2014

In this paper, a coil typed electromagnetic band gap (EBG) structure to be inserted in the printed circuit board (PCB) inner layer in order to stabilize the PCB power line is proposed and implemented for global-navigation satellite service (GNSS) with the bandwidth from 1.55GHz to 1.81GHz. From the measurement result of the PCB board including EBG structure, the insertion loss(S21) was measured below about -50dB. From these results, it is expected that the stabilization of power delivery network (PDN) structure in the PCB circuit design should be improved and the preparation to EMI will be effective.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.11
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• pp.1645-1650
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• 2015

This paper presents the 3-dimensional electromagnetic field analysis method and correction of sensor distortion that is used by a motor speed sensor. The magnetic sensors are being expanded due to lower price than the other speed sensors such as resolver and encoder. Magnetic sensor generates sine and cosine waves when the motor rotates. However, the sine and cosine signals are distorted due to magnetic noise, which makes the angle error of the sensor, generated near by the Hall element. This paper defines an optimal design variables by using the Taguchi method to minimize output distortion of the magnetic sensor and permanent magnet. To enhance reliability of the magnetic position sensor from sensitivity error, assembly amplitude mismatch and the electrical angle, 3-Dimensional electromagnetic finite element method and correction algorithm errors were performed in due of the magnetic sensor in order to improve the quality of the initial production model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.9
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• pp.821-827
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• 2015

Electromagnetic waves which are emitted from the Sun due to solar flare explosion can cause failures in HF radio communications in the day-side area of the Earth, that is so-call as Radio Blackouts. The international scale representing the severity of the Radio Blackouts is determined by the solar X-ray flux which is measured by United States Geostationary Operational Environmental Satellite. However, the scale is not always applicable to HF communication users in the different area on the Earth, because the HF communication effects depend not only on the X-ray strength but also on the subsolar point location. To solve this problem, we developed a HF radio spectrum monitoring system utilizing a spectrum analyzer. This system conducts a real-time measure of the HF spectrum, and automatically calculates signal to noise ratios and the occurrences of the HF blackouts as comparing with the interference level which is described from the ITU recommendation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.191-199
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• 2008

In this paper, we present a performance analysis and design and implementation results of a 2.4 GHz bio-radar system that can detect human heartbeat and respiration signals. In order to design a 2.4 GHz bio-radar system qualitatively, we investigate the electromagnetic properties of human tissues and calculate the target SNR of demodulation output with respect to distance. The target SNR is defined by the 90 % success ratio for detecting heartbeat signal. With this target SNR value, the performance and link budget of the bio-radar system is simulated using MATLAB. Using this link budget results, the direct conversion receiver is designed and Implemented in 4 layer printed circuit board(PCB). With output power of 0 dBm and 5 Hz bandwidth, 80 % success ratio of 50 cm is measured. Measurement results show a good agreement with simulation results.

• Economic and Environmental Geology
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• v.39 no.4 s.179
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• pp.427-440
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• 2006

Electromagnetic(EM) survey has been in use for over a half century as a standard routine for, mineral exploration in many parts of the world. But EM survey work and serious research effort were initiated in Korea only as late as in early 1980s, largely inspired by four pioneers who did their graduate studies in the U.S.A. in 1970s. Nevertheless domestic achievements in the field of EM survey are remarkable in the last two decades: the field operations and related interpretational skills appear to have reached a global standard, even compared with the most advanced in other countries, virtually in a whole spectrum of the method which includes magneto-tellurics(MT), Controlled Source Audio-frequency Magneto-tellurics(CSAMT), geomagnetic sounding, small loop survey systems, Very Low Frequency(VLF), Ground Penetrating Radar(GPR), time domain surveys, and noise analysis. Besides mineral exploration, EM survey has been applied in Korea to hydrogeology, geotechnical engineering, non-destructive investigation of structures, unexplored ordnance(UXO) investigation, environmental monitoring, and archaeological investigation as well. Now that original contributions of several Korean geophysicists are found even in new frontiers such as high-frequency EM survey, investigation in time-domain EM field for buried metal objects and structures, and also modem data inversion scheme, it is duly hoped that they make some technical breakthrough to unravel still entangled knots of EM survey method in a forseeable future.

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.282-289
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• 2011

GHz electromagnetic interference (EMI) characteristics are analyzed for a 3dimensional (3D) stacked chip power distribution network (PDN) with through silicon via (TSV) connections. The EMI problem is mostly raised by P/G (power/ground) noise due to high switching current magnitudes and high PDN impedances. The 3D stacked chip PDN is decomposed into P/G TSVs and vertically stacked capacitive chip PDNs. The TSV inductances combine with the chip PDN capacitances produce resonances and increase the PDN impedance level in the GHz frequency range. These effects depend on stacking configurations and P/G TSV designs and are analyzed using the P/G TSV model and chip PDN model. When a small size chip PDN and a large size chip PDN are stacked, the small one's impedance is more seriously affected by TSV effects and shows higher levels. As a P/G TSV location is moved to a corner of the chip PDNs, larger PDN impedances appear. When P/G TSV numbers are enlarged, the TSV effects push the resonances to a higher frequency range. As a small size chip PDN is located closer to the center of a large size chip PDN, the TSV effects are enhanced.