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CO<SUB>2</SUB> Adsorption of Amine Functionalized Activated Carbons
Longyue Meng,Ki-Sook Cho,Soo-Jin Park 한국탄소학회 2009 Carbon Letters Vol.10 No.3
In this work, the CO2 adsorption behaviors of amine functionalized activated carbons (ACs) were investigated. The surface of ACs was modified with urea, melamine, diethylenetriamine (DETA), pentaethylenehexamine (PEHA), polyethylenimine (PEI), and 3-aminopropyl-triethoxysilane (ATPS). The various surface properties of amine functionalized ACs were characterized by Boehm's method, nitrogen full isotherms, XPS, and TGA analyses. The active ingredients impregnated on the ACs show significant influence on the adsorption for CO2 and its volumes adsorbed on amine functionalized ACs are larger than that on the pristine ACs, which is due to the grafted amine groups of the AC surfaces.
Longyue Qu,Haiyan Piao,Guohui Dong 한국전자통신연구원 2023 ETRI Journal Vol.45 No.2
In this study, we developed a co-located and space-shared multiple-input multiple-output (MIMO) antenna module with a modular design and high integration level. The proposed antenna pair includes a half-wavelength loop antenna and a dipole-type antenna printed on the front and back sides of a compact modular board. Owing to their modal orthogonality, these two independent antenna elements are highly self-isolated and free of additional decoupling components, even though they are assembled at the same location and within the same space. Thus, the proposed antenna is attractive in 5G MIMO systems. Furthermore, the proposed co-located and space-shared MIMO antenna module was employed in a 5G smartphone to verify their radiation and diversity performances. A 12 × 12 MIMO antenna system was simulated and fabricated using the proposed module. Based on the results, the proposed module can be employed in large-scale MIMO antenna systems for current and future terminal devices owing to its high integration, compactness, simple implementation, and inherent isolation.
Qu, Longyue,Zhang, Rui,Shin, Hyunwoong,Kim, Jihoon,Kim, Hyeongdong Institute of Electrical and Electronics Engineers 2017 IEEE transactions on antennas and propagation Vol.65 No.2
<P>In this communication, we introduce a mode-controlled ground radiation antenna comprised of a resonance-controlled ground plane and a nonradiating feeding slot for wideband applications in mobile devices. A 110 mm <TEX>$\times50$</TEX> mm ground plane for 850-MHz operation is studied as a test case. The resonant frequency of the ground plane is lowered by adding metal loads at the top and bottom intended for strong coupling with a miniature feeding slot located at one end, so that the ground plane is resonant as a half wavelength dipole-type radiator. The metal loads can be the structures of strips, plates, or wires, and they can take the form of broken metal rims or frames with cuts or gaps in smartphones. In addition, the metal loads are connected to the ends of the ground plane by lumped elements (inductors and/or capacitors) for easy control of the resonance mode and compact design. Equivalent circuit model and corresponding equations are provided for theoretical analysis. The impedance bandwidth based on 3:1 VSWR is 210 MHz (from 760 to 970 MHz), with an average efficiency of 77%. Geometrical characteristics of the metal loads are shown to be important parameters for the antenna performance.</P>
High-Sensitivity Ground Radiation Antenna System Using an Adjacent Slot for Bluetooth Headsets
Qu, Longyue,Zhang, Rui,Kim, Hyeongdong Institute of Electrical and Electronics Engineers 2015 IEEE Transactions on Antennas and Propagation Vol. No.
<P>In this communication, we introduce a high-sensitivity antenna system for Bluetooth headsets dealing with the numerous and unidentified noises in a printed circuit board (PCB). This antenna system is composed of a ground radiation antenna for Bluetooth applications and an adjacent slot for noise suppression. A loop-type circuit is used to model a noise source on the PCB to provide wide-frequency spectrum noise currents to analyze the noise performance of the high-sensitivity antenna system. Decoupling between the noise sources and the antenna port can lead to high sensitivity. An adjacent slot is designed as part of the system to improve the sensitivity, based on the decoupling theorem. This proposed system is effective and applicable for high-sensitivity antenna design, as verified through simulation and active measurements of Bluetooth headsets.</P>
MIMO antennas using controlled orthogonal characteristic modes by metal rims
Qu, Longyue,Lee, Hongkoo,Shin, Hyunwoong,Kim, Min-Gi,Kim, Hyeongdong IET 2017 IET microwaves, antennas & propagation Vol.11 No.7
<P>A metal-rimmed multiple-input multiple-output (MIMO) antenna design operating below the 1 GHz frequency band is proposed that offers a wide bandwidth, high isolation, low correlation, and compact size. The proposed technique is based on metal-rimmed mobile phones with four gaps, and the overall design occupies a small size in the ground plane. Orthogonal ground mode resonances are controlled to be equal to the operating frequencies, providing high antenna performance and good diversity performance. The proposed main antenna is achieved by utilizing the upper-side rim to tune the ground mode resonance along the length of the ground plane to be equal to the operating frequency; moreover, a coupling slot couples strongly with the ground mode resonance to achieve a -6 dB bandwidth from 0.695 to 1 GHz (305 MHz). The orthogonal ground mode along the width of the ground plane is used for diversity antenna design. Similarly, the ground mode resonance is made equal to the operating frequency by controlling the left-side metal rim such that a simulated -6 dB bandwidth from 0.850 to 0.920 GHz (70 MHz) is achieved. The simulated isolation is more than 11.5 dB in the operating band, and the measured envelope correlation coefficients is below 0.1.</P>