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373 results on '"Yu, Jong-Won"'

5. Wireless Electric Field Sensor With Adaptive Voltage Gain for Measuring an Electrical Potential Treatment Chair

Author

Kim, Seong-Jin, Lim, Seong-Ju, Hwang, Sung-Jae, and Yu, Jong-Won

Abstract

A wireless electric field sensor for measuring an electrical potential treatment chair is proposed. Research on the treatment effects of the electric field generated by high-voltage (HV) electrodes at low frequencies, in this case, 50 or 60 Hz, has been conducted. However, most studies have only provided the value of the voltage applied to the HV electrodes, not the electric field generated by those. Therefore, it is necessary to provide the value of the electric field to verify the treatment effects. Because the electric field by the chair is too high to be measured by conventional sensors, it is necessary to develop a sensor that can adaptively measure the low and high electric field. The proposed sensor has an adaptive voltage gain that relies on digital potentiometers, which exert control for the proper gain depending on the field strength. Using a capacitive dipole probe, the electric field generated by the HV electrodes applied the voltage of 7.2 kV at 60 Hz was measured at diverse distances. It was found that the electric field was measured from 1.3 to 45.5 kV/m. For wireless notification, the sensor is equipped with a Wi-Fi module in a microcontroller unit.

Published
2024
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9. A Compact RF Energy Harvesting System With an Improved Impedance Matching Network

Author

Kim, Seong-Jin, Kim, Sol, Lee, Ji-Hoon, and Yu, Jong-Won

Abstract

This letter presents a compact RF energy harvesting (RFEH) system with an improved impedance matching network. The antenna includes a matching network consisting of periodic stubs, making it possible not only to adjust $S_{11}$ when it changed due to fabrication errors but also to design the antenna to be more compact. We initially analyzed the effects of the fabrication errors and variations of $S_{11}$ with respect to an adjustment of the matching network using an EM simulation. The antenna dimensions overall are 14.5 × 18.5 $\text{mm}^{\text{2}}$, and it is integrated with an RFEH circuit consisting of a rectifier and power management unit, which compose the RFEH system. The proposed system was implemented, charging a load capacitor at the received power of −15 and −5 dBm; therefore, the proposed system with the impedance matching network contributes to compactness and can be utilized as the power source for compact Internet of Things sensors.

Published
2024
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43. RFID reader front-end having robust Tx leakage canceller for load variation

Author

Lim, Won-Gyu, Park, Seo-Young, Son, Wang-Ik, Lee, Moon-Que, and Yu, Jong-Won

Subjects
Radio frequency identification (RFID) -- Design and construction, Antennas (Electronics) -- Design and construction, Directional couplers -- Usage, Radio frequency identification, Business, Computers, Electronics, Electronics and electrical industries
Abstract

A novel front-end structure for ultra-high-frequency RF identification reader is proposed. The proposed front-end consists of a balanced coupler and four-port feed antenna system. The proposed balanced coupler structure has high transmit/receiver isolation feature and good insensitivity to load variations. The proposed four-port feed antenna system is applied for removing the coupling among antennas, which deteriorates the isolation. The proposed system is numerically analyzed and verified experimentally as well. Index Terms--Antenna isolation, directional coupler, load impedance variation, ultra-high-frequency (UHF) RF identification (RFID).

Published
2009

50. Performance analysis of single-frequency CW signal-based I/Q regeneration in five-port junction-based direct receivers on Rayleigh fading channels

Author

Park, Hyung Chul, Lim, Hyung-Sun, and Yu, Jong-Won

Subjects
Communications circuits -- Design and construction, Rayleigh scattering -- Evaluation, Circuit design -- Evaluation, Circuit designer, Integrated circuit design, Business, Computers and office automation industries, Electronics, Electronics and electrical industries
Abstract

This paper analyzes the influence of the Rayleigh fading channel on the performance of a single-frequency continuous-wave (CW) signal-based I/Q regeneration in five-port junction-based direct receivers. This method uses a single-frequency CW signal to estimate the I/Q regeneration parameters. Simulation results show that the eye diagram, error vector magnitude, and bit error rate performances of five-port junction-based direct receivers using a single-frequency CW signal-based I/Q regeneration are almost the same as those of conventional coherent demodulators, even in fading channels. Index Terms--Coherent demodulation, five-port junction, I/Q regeneration, Rayleigh fading channel.

Published
2008

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