• Journal of the Korean institute of surface engineering
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• v.45 no.1
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• pp.43-52
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• 2012

Recently, it has been developed for Eco-environment, Super light, Multi-functional nano materials. As needed mobile parts in Smart phone or TV, computer, information communication for high pass signal, multi-function, Magnetic thin film materials have been developed. As last, magnetic powder, sintered and sputtering parts were thick and low purity than electroplating layer, low pass signal and noise were resulted, vibrated TV screen. Because chemical complex temperature was high and ununiform surface layer, it has been very difficult for data pass in High Frequency (GHz) area. Large capacity data pass is used to GHz. Above GHz, signal pass velocity is dependent on Skin Effect of surface layer. If surface layer is thick or ununiform, attachment is poor, low pass signal and cross talk, noise are produced and leaked. It has been reported technical trend of Electrochemically plating and Surface treatment of Metal, Polymer, Ceramic etc. by dispersion/complex for Multi functional nano-magnetic material in this paper.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.6
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• pp.409-416
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• 2005

For broadband high-data-rate power line communication with the allocated frequency bandwidth from 2 to 30 MHz on medium voltage (MV) distribution power lines, a signal coupling unit is developed. The coupling unit is composed of a coupling capacitor for coupling communication signal, a drain coil, and an impedance matching part. The coupling capacitor made of ceramic capacitor is designed for transmission property of better than 1 dB in the frequency range. The drain coil is used for preventing low frequency high voltage from junction of medium voltage power line in case that a coupling capacitor is not working properly any more. Also, using ferrite core, a novel broadband impedance matching transformer is developed. A complete coupling unit with a coupling capacitor, a drain coil, and a matching transformer is housed by polymer for good isolation and distinguishing from high voltage electric facilities. Each is fabricated and its frequency behavior is tested. Finally, complete signal couplers are equipped in a MV PLC test bed and their performance are measured. The measurement shows that the coupling capacitor works excellently.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.11
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• pp.512-515
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• 2003

This paper is to investigate how partial discharge pulse signal can flow in 6.6㎸ motor stator windings. Pulse propagation is experimentally analyzed in stator windings using a variety of frequency-domain techniques. The experiments were performed on two stator windings in the laboratory. Spectrum analyzer(9KHz to 3㎓) with tracking generator(100kHz to 3㎓) was used. Sweep time of the tracking generator was looms. The frequency spectrum of the response signal was detected by active FET probe(1㎓). The active FET probe has a flat amplitude response up to 1㎓ without high frequency attenuation. The stator winding acts as a low-pass filter below 600KHz, the high-frequency components being highly declined. The resonance peaks show about 1.1MHz and 2MHz in low frequency of No. 1 and No. 2 stator windings, respectively. This low-frequency range indicates that attenuation is low. The peaks of partial discharge magnitude show about 900MHz, 1.6MHz in No. 1 stator winding and about 800KHz, 1.4MHz in No. 2 stator winding.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.73-80
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• 2013

In this paper, an experimental circuit model for an accurate high-frequency characterization of transmission line is proposed. Inherent resonance effects during measurements make it difficult to determine characteristic impedance and propagation constant at the resonance frequencies corresponding to the line length. Thus, resonance-effect-free transmission line parameter determination technique based on the physical insight and theory is proposed. Then, by using the parameters high-frequency circuit model is proposed for high-speed signal propagation characterization. The proposed frequency-variant transmission line model is verified with measurement and it can be usefully exploited in high-speed signal propagation characterization.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.8
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• pp.647-650
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• 2003

PLC (Power Line Communication) is the communication method using the existing power line installed in houses and offices to convert and transmit high frequency communication signal from tens of KHz to tens of MHz, and receive the filtered signal using high frequency filter The advantage of PLC is that PLC uses the existing power line installed in houses and offices so it does not require separate power line. Easy and convenient access using electric outlets is another advantage of PLC. However, PLC has some disadvantages such as limited transmission power, high load interference and noise, variable signal attenuation, characteristic of impedance, and selective possibility of frequency property. We designed the boiler temperature control system unit by using the PLC modem. We can avoid unnecessary heating of separate temperature control unit, and save the cost accordingly control stability of the proposed system is proven through the experiment.

• Journal of the Korea Convergence Society
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• v.8 no.7
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• pp.1-6
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• 2017

This paper presents the design of a frequency measurement device using ADC, EP2AGX FPGA and STM32 processor to accurately measure the frequency of a broadband high frequency signal. The ADC device used in this paper has a sampling frequency of 250 MSPS and a processing frequency bandwidth of 100 MHz. Due to its high sampling frequency, it is difficult to process in ordinary computers or processors, so we implemented the frequency measurement algorithm using the Altra EP2AGX FPGA. The measured frequency is sent to the direction detection controller in real time and fused with the phase signal to calculate the incident azimuth angle of the high frequency signal. The designed frequency measurement device is about 0.2 Mhz in frequency measurement error and 30% less than Anaren DFD-x, which is considered to contribute greatly to the design of radio monitoring and direction detection device.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2783-2785
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• 2003

In multi-dimensional magnetic resonance imaging, data is obtained in the spatial frequency domain. Since the signal variation in the spatial frequency domain is much larger than that in the spatial domain, analog-to-digital converts with wide conversion bits are required. In this paper, the quantization noise in magnetic resonance imaging is analyzed. The signal-to-quantization noise ratio(SQNR) in the reconstructed image is derived from the level of quantization in the data acquisition. Since the quantization noise is proportional to the signal amplitude, it becomes more dominant in high field imaging. Using the derived formula the SQNR for several MRI systems are evaluated, and it is shown that the quantization noise can be a limiting factor in high field imaging, especially in three dimensional imaging in magnetic resonance imaging.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.10
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• pp.2883-2902
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• 2023

Since the existing anti-jamming methods, including intelligent methods, have difficulty against high-speed reactive jamming, we studied a new methodology for jamming utilization instead of avoiding jamming. Different from the existing jamming utilization techniques that harvest energy from the jamming signal as a power supply, our proposed method can take the jamming signal as a favorable factor for frequency detection. Specifically, we design an intelligent differential frequency hopping communication framework (IDFH), which contains two stages of training and communication. We first adopt supervised learning to get the jamming rule during the training stage when the synchronizing sequence is sent. And then, we utilize the jamming rule to improve the frequency detection during the communication stage when the real payload is sent. Simulation results show that the proposed method successfully combated high-speed reactive jamming with different parameters. And the communication performance increases as the power of the jamming signal increase, hence the jamming signal can help users communicate in a low signal-to-noise ratio (SNR) environment.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.192-197
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• 2008

High-speed harmonic optical modulation-demodulation schemes are presented and a possibility of the schemes for applying to high-speed light wave transmission system is tested at microwave frequency range. An example of this concept is as follows : Light wave is modulated succeedingly through cascaded optical modulators by a sub-carrier to produce a modulated light wave at harmonic frequency which is higher than the feasible frequency of the individual modulators. For demodulation of the base-band signal, the high frequency optical sub-carrier is down-converted by the same kind of optical modulator with the same concept of harmonic modulation.

• Journal of IKEEE
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• v.23 no.3
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• pp.1038-1045
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• 2019

This paper describes high-speed duobinary transceiver design techniques which are widely used to increase data-rate despite limited channel bandwidth. At high data-rate, signal level is severely degraded as signal frequency becomes larger than the channel bandwidth. Mathematically, a duobinary signal has lower frequency components compared to a Non-Return-to-Zero signal for the same data-rate. Therefore, by using the duobinary signaling, the signal loss can be effectively reduced in physical channel environment as compared to the Non-Return-to-Zero signaling. The mathematical basis of duobinary signaling, and its applications to high-speed transceiver design are investigated in this paper.