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Your search keyword '"Yoon, Ick-Jae"' showing total 118 results
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118 results on '"Yoon, Ick-Jae"'

7. Ferrite-Loaded, Low-Profile Grounded Bowtie-Loop Antenna for VHF Communication

Author

Kim, Wonkyo, Lee, Mee-Su, Shin, Geonyeong, Kim, Hyun, Lee, Chang-Hyun, Kim, Youngwan, and Yoon, Ick-Jae

Abstract

This letter presents a ferrite core-loaded, low-profile antenna for very high frequency (VHF) communication. The proposed antenna takes the form of a magnetic dipole source on a conducting ground for vertical polarization on the integrated mast of a battleship. In practice, a bowtie loop is grounded, and a ferrite core is internally loaded to decrease operating frequencies. The Ferrite core is used for antenna miniaturization, as it stores magnetic energy inside the resonant core of the antenna. The size of the proposed antenna with a housing assembled for stable loading at the mast is 0.12 × 0.053 × 0.0076 [${\bm{\lambda }}$3] with respect to the lowest matched frequency of 36.8 MHz, with a criterion VSWR of less than 3. The measured realized gain at 30 MHz is –16.9 dBi, demonstrating the upward trend across the VHF band and the sufficiently high value given the antenna size. The proposed antenna achieves the highest realized gain at the lowest operating frequency among the previously reported ferrite core-loaded VHF antennas.

Published
2023
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8. Ferrite-Loaded Inverted Microstrip Line-Based Artificial Magnetic Conductor for the Magnetic Shielding Applications of a Wireless Power Transfer System.

Author

Radha, Sonapreetha Mohan, Choi, Seong Hoon, Lee, Jae Ho, Oh, Jung Hoon, Cho, In-Kui, and Yoon, Ick-Jae

Subjects
MAGNETICS, MICROSTRIP transmission lines, RADIATION shielding, SUPERCONDUCTING coils
Abstract

In this paper, we propose a ferrite-loaded inverted microstrip line (IML)-based artificial magnetic conductor (AMC) with a novel design that can provide complete magnetic shielding at the backside of the transmitting (Tx) coil while slightly improving the power transfer efficiency (PTE) of a wireless power transfer system (WPTS). The target frequency of the WPTS application is approximately 6.78 MHz. In the proposed design, the AMC is placed behind the Tx coil, and its magnetic shielding capability and PTE performance were verified through simulations and measurements. The size of the proposed AMC is 528 × 528 × 6.6 mm3. The measurement results verified that, compared with the Tx coil without an AMC surface, the proposed ferrite-loaded IML-based AMC can provide complete magnetic shielding while improving the PTE of the WPTS by approximately 8.05%. [ABSTRACT FROM AUTHOR]

Published
2023
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24. Electrospun Polyvinylidene Fluoride Nanofibers with Embedded Fe3O4 Nanoparticles and Conductive Poly(3,4-ethylenedioxythiophene) Shells for Electromagnetic Interference Shielding.

Author

Lee, Sol, Kim, Chang Geun, Kim, Minje, Park, Joomin, Yoon, Ick-Jae, and Nah, Junghyo

Abstract

Flexible and lightweight electromagnetic interference (EMI) shielding materials with excellent EMI shielding performance have attracted significant attention because of their potential applications in various fields. In this study, we reported the fabrication and performance of polyvinylidene fluoride (PVDF) composite nanofiber (NF) EMI shielding materials composed of Fe3O4 nanoparticles (NPs)-embedded PVDF and conductive poly-(3,4-ethylenedioxythiophene) (PEDOT) shells. By separating the conductive NF surface, which was prepared using a vapor phase polymerization (VPP) method, from the magnetic nanoparticle region inside the NF, high conductivity of the shell can be maintained and unaffected even when the wt % of Fe3O4 NPs inside the NF is increased. Therefore, the EMI shielding performance can be maximized by simultaneously increasing the conductivity and permeability of the NFs. Fe3O4 NPs embedded in the NF also contributed to increasing permeability and interfacial polarization, boosting multiple reflection and scattering, and absorption of incident EM waves through magnetic and dielectric loss. Additionally, the multi-layered NF structure is suitable to facilitate a multiple reflection mechanism. Consequently, high EMI SE and absolute EMI shielding effectiveness (SSEt) of 18,760 dB·cm2/g were achieved. The EMI shielding material developed in this study can easily be adopted for various applications because of its superb flexibility, hydrophobicity, ultrathin thickness, and robustness. [ABSTRACT FROM AUTHOR]

Published
2022
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28. A novel fully integrated transmitter front-end with high power-added efficiency

Author

Kim, Hyungrak, Yoon, Ick-Jae, and Yoon, Young Joong

Subjects
Business, Computers, Electronics, Electronics and electrical industries
Abstract

A novel fully integrated transmitter front-end with a simple structure is proposed to obtain both high power-added efficiency (PAE) and a compact RF-front structure. To have all these characteristics, a novel antenna operating as a radiator, a harmonic tuning circuit, and an output matching network of the power amplifier is proposed. Therefore, the direct integration of the output of the power amplifier and antenna can be achieved without any impedance transformers. From the measured results and fabrication, it is shown that the proposed transmitter front-end provides high PAE of 67.5% and compact and integrated RF-front structure by the size reduction of 43% compared with the conventional class-F active antenna for high PAE. Index Terms--Direct integration, fully integrated transmitter front-end, harmonic tuning, power-added efficiency (PAE), power amplifier.

Published
2005

46. Experimental and comparative study of mechanical and electromagnetic aspects of a high-speed permanent magnetic motor with two different magnetic materials.

Author

Woo, Jong-Hyeon, Bang, Tae-Kyoung, Kim, Chang-Woo, Yoon, Ick-Jae, and Choi, Jang-Young

Subjects
MAGNETIC materials, PERMANENT magnet motors, RARE earth metals, PERMANENT magnets, COMPARATIVE studies, FERRITES
Abstract

This paper compares permanent magnet synchronous motors with rare earth permanent magnets (PM) and those with ferrite PM, and it suggests that ferrite PM can replace rare earth PM. Therefore, the two models with the same output were compared and analyzed by comparing the mechanical and electromagnetic characteristics. Finally, the study is validated experimentally. [ABSTRACT FROM AUTHOR]

Published
2020
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