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Overview of Full-Dimension MIMO in LTE-Advanced Pro
Ji, Hyoungju,Kim, Younsun,Lee, Juho,Onggosanusi, Eko,Nam, Younghan,Zhang, Jianzhong,Lee, Byungju,Shim, Byonghyo Institute of Electrical and Electronics Engineers 2017 IEEE communications magazine Vol.55 No.2
<P>Multiple-input multiple-output (MIMO) systems with a large number of base station antennas, often called massive MIMO, have received much attention in academia and industry as a means to improve the spectral efficiency, energy efficiency, and processing complexity of next generation cellular systems. The mobile communication industry has initiated a feasibility study of massive MIMO systems to meet the increasing demand of future wireless systems. Field trials of the proof-of-concept systems have (demonstrated the potential gain of the Full-Dimension MIMO (FD-MIMO), an official name for the MIMO enhancement in the 3rd generation partnership project (3GPP). 3GPP initiated standardization activity for the seamless integration of this technology into current 4G LTE systems. In this article, we provide an overview of FD-MIMO systems, with emphasis on the discussion and debate conducted on the standardization process of Release 13. We present key features for FD-MIMO systems, a summary of the major issues for the standardization and practical system design, and performance evaluations for typical 1D-MIMO scenarios.</P>
Food waste-driven N-doped carbon dots: Applications for Fe<sup>3+</sup> sensing and cell imaging
Ahn, Jungbin,Song, Younghan,Kwon, Ji Eon,Lee, Sang Hyun,Park, Ki Soo,Kim, Seokjoon,Woo, Jeongyeon,Kim, Hyungsup Elsevier 2019 Materials science & engineering. C, Materials for Vol.102 No.-
<P><B>Abstract</B></P> <P>We report highly fluorescent N-doped carbon dots (CDs) synthesized from food waste via one-step hydrothermal carbonization. To study the chemical transition of carbon dots from food wastes, the cat feed stocks driven from food waste were used as the waste model. In the model study, the core of the CDs was successfully self N-doped without extra pre- or post-treatments. The experimental results reveal that the nitrogen in the waste model played an important role in the formation of graphitic N and pyridinic N in the core and functional groups on the surface. Especially, high process temperature (≥180 °C) resulted in high quantum yield as 23% of the CDs from the waste model. To demonstrate the conversion of real food waste into CDs, the hamburger sandwich leftover was used as a precursor for CDs. The food waste driven CDs had similar chemical and fluorescent properties to that of the waste model, having quantum yield of 28%. This study exhibits the food waste driven carbon dots are excellent candidates for fluorescence probe to Fe<SUP>3+</SUP> with high selectivity even under the interference of other metal, and for bio-imaging material with good cell viability over 80%.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Bender Typed Piezoelectric Multilayer Actuator
Byung-GukAhn,Dong-KyunLee,Deuk-YoungHan,강종윤,Ji-WonChoi,Hyun-JaiKim,Seok-JinYoon 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.3
A bender typed multilayer actuator (BMA) for decreasing the depolarization effect was designed and fabricated. Unlike bimorph and multimorph actuators in which depolarization occurred, the BMA did not generate depolarization because the polarization and the electric field directions are the same. The simulated results indicate that higher displacement of the BMA can be achieved by increasing input voltage. Compared with the multimorph actuator, the proposed actuator is expected to extend a life time as well as acceptable voltage range.