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Advanced Magnetic Materials Produced by Using Rapid Quenching Technology
Nguyen Hoang Nghi,Nguyen Van Dung,Trinh Thi Thanh Nga,Bui Thi Khanh Nhung,Mai Thanh Tung,Nguyen Huu Tinh,Hoang Nhat Hieu,Bui Xuan Chien,Nguyen Thi Hong Tam 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.6
Amorphous alloys produced by using a rapid quenching technique are considered to be a precursor for producing nanosized and multiphase structures by precipitation (the top-down method). By using this technique, several new magnetic materials with different magnetic properties based on different physical mechanisms have been manufactured and investigated. Three new magnetic materials, a nanocrystalline soft magnetic material, a soft-hard permanent magnet and a Me-3d granular alloy with a GMR effect, what were prepared under local conditions, are presented and discussed in the experimental point of view. Amorphous alloys produced by using a rapid quenching technique are considered to be a precursor for producing nanosized and multiphase structures by precipitation (the top-down method). By using this technique, several new magnetic materials with different magnetic properties based on different physical mechanisms have been manufactured and investigated. Three new magnetic materials, a nanocrystalline soft magnetic material, a soft-hard permanent magnet and a Me-3d granular alloy with a GMR effect, what were prepared under local conditions, are presented and discussed in the experimental point of view.
A Piezoelectric Energy Harvester with High Efficiency and Low Circuit Complexity
Xuan-Dien Do,Huy-Hieu Nguyen,Seok-Kyun Han,Dong Sam Ha,Sang-Gug Lee 대한전자공학회 2015 Journal of semiconductor technology and science Vol.15 No.3
This paper presents an efficient vibration energy harvester with a piezoelectric (PE) cantilever. The proposed PE energy harvester increases the efficiency through minimization of hardware complexity and hence reduction of power dissipation of the circuit. Two key features of the proposed energy harvester are (i) incorporation synchronized switches with a simple control circuit, and (ii) a feed-forward buck converter with a simple control circuit. The chip was fabricated in 0.18 μm CMOS processing technology, and the measured results indicate that the proposed rectifier achieves the efficiency of 77%. The core area of the chip is 0.2 mm2.
A Piezoelectric Energy Harvester with High Efficiency and Low Circuit Complexity
Do, Xuan-Dien,Nguyen, Huy-Hieu,Han, Seok-Kyun,Ha, Dong Sam,Lee, Sang-Gug The Institute of Electronics and Information Engin 2015 Journal of semiconductor technology and science Vol.15 No.3
This paper presents an efficient vibration energy harvester with a piezoelectric (PE) cantilever. The proposed PE energy harvester increases the efficiency through minimization of hardware complexity and hence reduction of power dissipation of the circuit. Two key features of the proposed energy harvester are (i) incorporation synchronized switches with a simple control circuit, and (ii) a feed-forward buck converter with a simple control circuit. The chip was fabricated in $0.18{\mu}m$ CMOS processing technology, and the measured results indicate that the proposed rectifier achieves the efficiency of 77%. The core area of the chip is 0.2 mm2.
A Hybrid Software Defined Networking Architecture for Next-Generation IoTs
( Ahyoung Lee ),( Xuan Wang ),( Hieu Nguyen ),( Ilkyeun Ra ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.2
Everything in the world is becoming connected and interactive due to the Internet. The future of interactive smart environments such as smart cities, smart industries, or smart farms demand high network bandwidth, high network flexibility, and self-organization systems without costly hardware upgrades, and they provide a sustainable, scalable, and replicable smart environment backbone infrastructure. This paper presents a new Hybrid Software-Defined architecture for integrating Internet-of-Things technologies that are essential technologies for smart environments. It combines a software-defined networking infrastructure and a real-time distributed network framework with an advanced optimization to enable self-configuration, self-management, and self-adaption for providing seamless communication and efficiently managing a vast number of smart heterogeneous devices.
Customer Satisfaction in Hotel Services: A Case Study of Thanh Hoa Province, Vietnam
LE, Quang Hieu,NGUYEN, Thanh Xuan Thi,LE, Thanh Thuy Thi Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.10
The study examines the influence of factors on customer satisfaction in hotel services in Thanh Hoa province of Vietnam. In terms of the tangible facilities of hotels, customers appreciate the availability and the full range of equipment and additional services, as the 3-to-5-star hotels in Thanh Hoa province are almost new, built in the last five years - 7 of 13 hotels were built in 2015. In the process of measuring the effect of factors on satisfaction in hotel services there, the researchers conducted exploratory factor analysis, reliability test, correlation and regression to confirm the relationships of factors. Based on a survey of 380 respondents, the test results showed that the proposed factors have positive impacts on consumer satisfaction; they are: perceived quality (including intangible and tangible elements), brand image, perceived value, and customer relationship management. In particular, intangible elements have the strongest influence on customer satisfaction, followed by tangible elements, brand image, perceived value, and finally, customer relationship management. In addition, the study found that foreigners and higher education customers tend to be more satisfied by the hotels than other groups, which helps to suggest important and appropriate solutions for hotel managers in Thanh Hoa province.
Duong, Vinh-Hao,Hieu, Nguyen Xuan,Lee, Hyun-Sik,Lee, Jong-Wook Institute of Electrical and Electronics Engineers 2016 IEEE transactions on industrial electronics Vol. No.
<P>Herein, we present a fully integrated electronic product code (EPC) Gen-2 compatible battery-assisted passive (BAP) radio-frequency identification sensor tag integrated circuit (IC) with efficient power management. The key components of the tag IC include an adaptive radio-frequency (RF) energy harvester, a battery access controller (BAC), a storage capacitor charger, and a power-gated sensor block. External RF energy is efficiently harvested using dynamically controlled rectifying stages and a threshold-compensation technique. The BAC tightly controls the power path, cutting off leakage current from the battery. The power-gated sensor block supports multiplexed sensing operations in a power efficient manner. The sensor interface includes a chopper amplifier, a programmable gain amplifier, multiplexers, and an 8-bit ADC. For sensing data logging, custom designed nonvolatile memory is employed via one-time programmable memory. The digital control block is based on an EPCglobal Gen-2 standard that is modified to support the sensing operation. The tag chip was fabricated in a 1-poly 6-metal standard 0.18-mu m standard CMOS process. The tag IC consumes 1 mu A for leakage and active operation (0.1% duty), and the estimated lifespan of the BAP tag IC is about 0.2 year/mA.h.</P>
La Nam Phat,Tran Quoc Thang,Huynh Cam Nguyen,Dang Thi My Duyen,Dao Xuan Tien,Bui Dang Dang Khoa,Pham Tan Khang,Nguyen Thi Huong Giang,Hoang Minh Nam,Mai Thanh Phong,Nguyen Huu Hieu 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.11
Recycling biomass to cellulose aerogel (Cell-A) provides a promising approach to develop adsorbent materials for spilled-oil recovery. In this work, Cell-A was fabricated from Vietnamese water hyacinth via crosslinking methods using PVA as a crosslinker and freeze-drying process. Various cellulose to PVA ratios were investigated to obtain the optimal synthesis condition. The Cell-A was additionally modified by dip-coating in poly(dimethylsiloxane) (PDMS) and pyrolyzing to form PDMS-coated cellulose aerogels (Cell-AP) and carbon aerogels (CA), respectively. Results of the oil adsorption tests show that pyrolysis produced aerogels with greater adsorption capacity with an optimal mass ratio of 15 : 1 cellulose to PVA. Furthermore, the pseudo-second-order model was found to be more accurate than the pseudo-first-order model for the study of oil absorption kinetics. As a result, the modified cellulose aerogel is promising for replacing earth-unfriendly polymer-based oil sorbents due to their high oil absorption capacity.