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Free-Positioning Wireless Power Transfer Using a 3D Transmitting Coil for Portable Devices
Nam Ha-Van,Hoang Le-Huu,Minh Thuy Le,Kwangsuk Park,Chulhun Seo 한국전자파학회JEES 2020 Journal of Electromagnetic Engineering and Science Vol.20 No.4
The free-positioning wireless power transfer (WPT) system has drawn attention in recent years. Traditionally, a WPT system can transfer energy in one or two directions on the same plane, but it leads the restrictions of angle and axis misalignment between a transmitter and a receiver coil. In this paper, we propose a free-positioning WPT system using a three-dimensional cubic-shaped transmitting coil for portable device charging. A small receiving coil is placed inside the transmitter to achieve the transferred energy through the magnetic resonant coupling. In addition, the equivalent circuit and the mutual inductance between the Tx and Rx coils are analyzed. Finally, a practical experiment is implemented to verify the transfer performance, which can reach up to about 50% power transfer efficiency. The proposed system can charge in spatial freedom.
Le Thu Trang,Dinh-Toi Chu,Nguyen Thi Hong Hanh,Nguyen Nam Trung 질병관리본부 2019 Osong Public Health and Research Persptectives Vol.10 No.2
Objectives: To identify trends in percentage body fat (PBF) in adolescents to determine gender-specific classification thresholds for being overweight and obese. Methods: A cross-sectional study of 899 adolescents (11 to 14.5 years) from Hanoi and Nam Dinh was conducted in Vietnam. PBF, subcutaneous fat and percentage of lean mass were measured directly using OMRON HBF 375 scales to measure bioelectrical impedance. Results: PBF decreased in boys with increasing age (p < 0.001). The difference in PBF between boys and girls, significantly increased with age after 12.5 years (p < 0.001). There was a stronger correlation between PBF and fat content (Pearson’s r = 0.860, p < 0.0001) than that between (BMI) and fat content (Pearson’s r = 0.521, p < 0.0001). The prevalence of being overweight or obese in girls was similar when determined by PBF or BMI. Hanoi had higher rates of adolescents being overweight or obese compared with Nam Dinh. Conclusion: PBF provides a more accurate body assessment for being overweight or obese in adolescents compared with BMI.
Survey of Promising Technologies for 5G Networks
Le, Nam Tuan,Hossain, Mohammad Arif,Islam, Amirul,Kim, Do-yun,Choi, Young-June,Jang, Yeong Min Hindawi Limited 2016 Mobile information systems Vol.2016 No.-
<P>As an enhancement of cellular networks, the future-generation 5G network can be considered an ultra-high-speed technology. The proposed 5G network might include all types of advanced dominant technologies to provide remarkable services. Consequently, new architectures and service management schemes for different applications of the emerging technologies need to be recommended to solve issues related to data traffic capacity, high data rate, and reliability for ensuring QoS. Cloud computing, Internet of things (IoT), and software-defined networking (SDN) have become some of the core technologies for the 5G network. Cloud-based services provide flexible and efficient solutions for information and communications technology by reducing the cost of investing in and managing information technology infrastructure. In terms of functionality, SDN is a promising architecture that decouples control planes and data planes to support programmability, adaptability, and flexibility in ever-changing network architectures. However, IoT combines cloud computing and SDN to achieve greater productivity for evolving technologies in 5G by facilitating interaction between the physical and human world. The major objective of this study provides a lawless vision on comprehensive works related to enabling technologies for the next generation of mobile systems and networks, mainly focusing on 5G mobile communications.</P>
Le-Phuc Nguyen,Yen Thi Hai Pham,Phuong Thuy Ngo,Tri Van Tran,Loc Vinh Tran,Nam Thi Hoai Le,Luong Huu Nguyen,Tung Thanh Dang,Duc Anh Nguyen,Marco Wenzel,David Hartmann,Karsten Gloe,Jan J. Weigand,Klaus 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.5
Acid leaching and a two-step solvent extraction procedure were developed to produce high purity mixture of La and Ce from iron-rich spent FCC catalyst discharged from Dzung Quat refinery (Vietnam). Acid leaching of the spent catalyst with 2M HNO3 and a solid-to-liquid ratio of 1/3 at 80 oC in 1 h dissolved almost 90% of La while 12% of Al and 25% of Fe were transferred to the leachate. The extraction of RE metals and main impurities such as Al and Fe by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) was investigated. Experiments showed that it was necessary to remove Fe before extracting RE and the optimum extraction conditions for a high recovery of RE while 0% of Al extraction were pH1, contact time=10min, and D2EHPA/TBP volume ratio= 4 : 1. At these conditions, the extraction yields of La(III) and Ce(III) were 72% and 89%, respectively. A two-step solvent extraction was developed to achieve a high purity of RE mixture, which included (1) the removal of impurity Fe by 25% (v/v) diisooctyl phosphinic acid (DiOPA) in n-octane for 140 min, (2) the extraction of rare earths by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) in n-octane for 10 min without the need for adjusting the pH of the leaching solution.
Morphological improvement of CH3NH3PbI3 films using blended solvents for perovskite solar cells
Nam Le,Nguyen Tam Nguyen Truong,Trang Le,Mohan Reddy Pallavolu,전혜준,박진호 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.1
Perovskite solar cells with the structure of glass/florine-doped tin oxide (FTO)/electron transfer layer (ETL)/ perovskite/hole transfer layer (HTL)/Ag were fabricated. The effects of blending solvents and thermal annealing on the surface morphology, structural, and optical properties of perovskite (CH3NH3PbI3) active layer were investigated. The active layer was optimized by adding 2-butanol (2-BTA) as an eco-friendly solvent into methyl ammonium iodide (MAI) solution used for spin coating on PbI2/(dimethylformamide (DMF)+dimethyl sulfoxide (DMSO)) film in the second step. The resulting morphology of CH3NH3PbI3 films was smooth and pinholes in the films were also reduced without change in the structure. The effects of thermal annealing on the surface morphology and structural properties of active layer were also studied. The fabricated device for the optimized condition showed the maximum power conversion efficiency (PCE) of ~8.6%.
A novel strain of porcine deltacoronavirus in Vietnam
Le, Van Phan,Song, Sok,An, Byung-Hyun,Park, Gyu-Nam,Pham, Ngoc Thach,Le, Dinh Quyen,Nguyen, Van Tam,Vu, Thi Thu Hang,Kim, Ki-Sun,Choe, SeEun,An, Dong-Jun Springer-Verlag 2018 Archives of virology Vol.163 No.1
<P>Two porcine deltacoronavirus (PDCoV) strains (Binh21 and HaNoi6) were isolated from two pig farms in North Vietnam. Phylogenetic analysis of the complete genomes and the Spike and Membrane genes revealed that the two Vietnam PDCoVs belong to the same lineage as PDCoVs from Thailand and Laos; however, the N genes belonged to the same lineage as PDCoVs from the USA, Korea, China, and Hong Kong. The recombination detection program subsequently identified the major parent (S5011 strain) and minor parent (HKU15-44 strain) of the two Vietnam PDCoV strains (p < 0.01).</P>