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Shielding Effectiveness of Open Cabinet Containing Digital Modules Using Ferrite Sheet
Choo, Jaeyul,Choo, Jaegul,Kim, Yong-Hwa IEEE 2017 IEEE transactions on magnetics Vol.53 No.12
<P>This paper presents an enhancement in the shielding effectiveness (SE) of an open cabinet containing digital modules using a ferrite sheet when an external electromagnetic source impinges on the gate of the cabinet. We perform an electromagnetic analysis on the inner space of an open cabinet using a mode-matching method, which proceeds in the following order: the separation of the analyzed region, the representation of fields, and the enforcement of the boundary conditions on the tangential field continuities between the separated regions. To be specific, it is efficiently utilized in the representation of electric and magnetic fields by Helmholtz’s equation in conjunction with both the separation of the variable and the Fourier transform. After confirming the convergence of the solutions to the set of simultaneous equations, we investigate the SE in the open cabinet in terms of a frequency, an incident angle, and the number and the size of slits. The computed results provide us with useful information for avoiding electromagnetic interference. We then examine the improvement of shielding performance by inserting a ferrite sheet at the gate of a cabinet. We verify that the usage of the ferrite sheet with high permeability can be a preferable solution for removing the undesirable problems caused by an external electromagnetic source.</P>
CHOO, Jaeyul,CHO, Chihyun,CHOO, Hosung 'Institute of Electronics, Information and Communi 2014 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.eb97 No.5
<P>This paper designs tag antennas to satisfy three key goals: mounting on very small objects, extending the reading range with planar structures, and maintaining stable performance on various materials. First, the size of the tag is reduced up to 17% compared to the half-wavelength dipole without a large reduction in bandwidth and efficiency by introducing an inductively coupled feed structure. Second, the reading range is increased to 1.68 times that of the reference dipole tags while maintaining the planar structure using circular polarization characteristics. Finally, a stable reading range is achieved with a deviation in the reading range of only 30% of that of commercial tags on various objects by employing the capacitively-loaded and T-matching network.</P>
Jaeyul Choo,Jeongki Ryoo,Hosung Choo 한국전자파학회JEES 2011 Journal of Electromagnetic Engineering and Science Vol.11 No.1
In this letter, we propose a novel tag antenna that has low performance degradation with nearby dielectric material. We obtained a stable reading performance and a broad matching bandwidth on nearby dielectric materials by employing a T-matching network with thick line width and capacitively slot-loaded arms. We then built the proposed antenna and measured the tag sensitivity to examine the reading characteristics with nearby dielectric materials. The measured results clearly demonstrate stable tag sensitivity with various nearby dielectric materials, such as foam, acrylic-plastic, glass, and ceramic plates. To more closely observe the antenna characteristics with nearby dielectric materials, we also examined the impedance variation and surface current distribution with respect to the dielectric constant of nearby target objects, which ranged from 1×ε? to 16×ε?.
Novel UHF RFID Tag Antenna for Metallic Foil Packages
Jeongki Ryoo,Jaeyul Choo,Hosung Choo IEEE 2012 IEEE transactions on antennas and propagation Vol.60 No.1
<P>A low-cost wideband antenna for radio-frequency identification (RFID) tags for use with metallic foil packages is designed in this communication. An proximity inductively coupled feed structure is employed to perform wideband impedance matching between a slot on a metallic foil package and a small rectangular feeding loop connected to a microchip. The results show a measured half-power bandwidth of 32.2% (799 MHz-1,093 MHz) and a reading distance of over 10 m.</P>
Lee, Hoon-Keun,Choo, Jaeyul,Shin, Gangsig,Kim, Sung-Man Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.12
A simple water level measurement method based on wavelength division multiplexing (WDM) is proposed and demonstrated. The measurement principle is based on the change of Fresnel reflection occurring at the end facet of the optical fiber tip (OFT). To increase the spatial resolution of water level sensing, a broadband light source (BLS) and an arrayed waveguide grating (AWG) are employed. The OFTs are multiplexed with the dedicated wavelength channels of AWG. By measuring all of the reflection powers reflected at the OFTs with a proposed on-site reflectometer, the water level can be monitored continuously for a fast emergency response. Moreover, it can be implemented easily with the commercially available optical components and devices with the simple configuration.
Lee, Hoon-Keun,Kim, Yong-Hwa,Choo, Jaeyul Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.10
This paper presents a mode-matching analysis of the electromagnetic coupling between open cable trays in an indoor structure when an electric-line current is generated as an electromagnetic source. We validated the mode-matching method by comparing the mode-matching results with those computed from a commercial electromagnetic simulator and then investigated the strength of the electric-field coupled in a victim cable tray while varying the distances between cable trays and architectural surfaces. The results of this study provide geometrical information on the placement of open cable trays to avoid electromagnetic interference problems.