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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.
Factors Affecting Employee’s Performance: An Empirical Study in Vietnam
Nguyen Xuan DIEN,Dang Thi Thuy DUYEN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.7
In the context of economic growth, the banking system has greatly contributed to a substantial rise in living conditions, connecting savings and investment, and economic growth. Since economic reform in 1986, Vietnam’s banking system has increasingly expanded in quality and quantity of banks including state-owned, private-owned, and foreign banks. The aim of this study is to evaluate the main factors affecting employee’s performance in the banking system in the case of an emerging economy of Vietnam. Using the pilot study by investigating three experts in a few banks in order to correct the questionnaires, and a mega sample data of 170 observations conducted from bank’s staffs, and managers in Hanoi capital of Vietnam, empirical results demonstrate that the independent variables included in the model can explain 67% of the change of the dependent variable of employee’s performance, and the rest (31%) can be explained by other reasons. Further, motivation (MO), and working ability (WA) have a positive and insignificant impact on employee’s performance, reflecting that motivation, and working ability have insignificantly affected employee’s performance. In contrast, four factors, namely, welfare, working environment, cooperation, and education have a positive and significant impact on employee’s performance in the case of Hanoi, Vietnam.
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.
( Dien Minh Vu ),( Binh Hoa Pham ),( Duc Pham Xuan ),( Dung Nguyen Dinh ),( Vinh Nguyen Duy ) 한국공업화학회 2023 공업화학 Vol.34 No.3
Fuel cells are one of the renewable energy sources that have sparked a lot of scientific attention for solving problems related to the energy crisis and environmental pollution. One of the most crucial subjects concerning the utilization of fuel cells is modeling. Therefore, an analytical steady-state and dynamic fuel cell model was described in this study. The parameter for the identification process was investigated, and the MATLAB/Simulink implementation was demonstrated. A 15-W proton exchange membrane fuel cell was used to apply the suggested modeling methodology. Comparing experimental and simulation findings indicated that the model error was constrained to 3%. This study showed that temperature and humidity affect fuel cell performance.
Liao Wu,Xuan-Dien Do,Sang-Gug Lee,Dong Sam Ha IEEE 2017 IEEE transactions on circuits and systems. a publi Vol.64 No.3
<P>This paper presents a piezoelectric energy harvest-which integrates a Synchronized Switch Harvesting on Inductor (SSHI) circuit and an active rectifier. The major design challenge of the SSHI method is flipping the capacitor voltage at optimal times. The proposed SSHI circuit inserts an active diode on each resonant loop, which ensures flipping of the capacitor voltage at optimal times and eliminates the need to tune the switching time. The diodes of the SSHI circuit are also used as a rectifier to further simplify the controller. The key advantage of the proposed circuit is a simple controller, which leads to low power dissipation of the proposed circuit to result in high efficiency. The proposed circuit isself-powered and capable of starting even when the battery is completely drained. The circuit was fabricated in BiCMOS 0.25 mu m technology with a die size of 0.98 x 0.76 mm(2). Measured results indicate that the proposed circuit increases the amount of power harvested from a piezoelectric cantilever by 2.1 times when compared with a full bridge (FB) rectifier and achieves a power conversion efficiency of 85%. The proposed circuit dissipates about 24 mu W while the controller alone only 1.5 mu W.</P>
A Long Reset-Time Power-On Reset Circuit With Brown-Out Detection Capability
Huy-Binh Le,Xuan-Dien Do,Sang-Gug Lee,Seung-Tak Ryu IEEE 2011 IEEE transactions on circuits and systems. a publi Vol.58 No.11
<P>A compact low-power on-chip power-on reset circuit with a brown-out detection capability is presented. With a pico-farad-order on-chip MOS capacitor, a long reset time is achieved. A prototype design implemented in a 0.18-μm CMOS process provides a reset signal with duration of hundreds of milliseconds. The embedded brown-out detection circuit can detect the event, as long as the brown-out duration is longer than the millisecond range. The chip consumes only 1 μA under a 1.8-V supply and occupies a 120 μm × 100 μm active area.</P>
A scintillation detector confi guration for pulse shape analysis
Phan Van Chuan,Nguyen Duc Hoa,Nguyen Xuan Hai,Nguyen Ngoc Anh,Nguyen Nhi Dien,Pham Dinh Khang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.8
This paper presents a neutron detector configuration using EJ-301 scintillation liquid, a R9420 photomultiplierand a homemade preamplifier. The detector qualities which include the energy linearity, efficiencyresponse and neutron/gamma discrimination are guaranteed for neutron detection in the energyrange from 0 to 3000 keVee. Regarding the neutron/gamma discrimination capability, four pulse shapediscrimination (PSD) methods which are the threshold crossing time (TCT), pulse gradient analysis (PGA),charge comparison (CC) and correlation pattern recognition (CPR), were evaluated and discussed; amongof these, the CPR method provides the best neutron/gamma discrimination
A Novel Chitosan-Gossypol Based Nanocarrier for Anticancer Curcumin Drug Delivery
( Ngoan Thi Nguyen ),( Lam Dai Tran ),( Duong Quang Le ),( Dien Gia Pham ),( Phuc Xuan Nguyen ),( Jun Seo Park ),( Jae Kweon Park ) 한국키틴키토산학회 2012 한국키틴키토산학회지 Vol.17 No.2
Gossypol chitosan (GPCS) nanoparticles have been successfully synthesized at the size of 20-40 nm through amidation process to forming base shift of polymer chains of chitosan using gossypol as a crosslinking agent. Their structure was confirmed by Fourier Transformed Infra Red (FT-IR) spectra. Morphology, stability, loading and releasing efficiency of GPCS and Cur/GPCS (Cur stands for curcumin) were thoroughly investigated by Field Emission Scanning Electron Microscopy (FESEM), FT-IR, Ultra Violet-Visible spectrophotometry (UV-Vis) and High Resolve Photoluminescence System (HRPLS). The obtained nanocarrier exhibited an excellent solubility for Cur anticancer drug as well as high stability for in vitro studies. An intensive fluorescence, allowing drug monitor/delivery, was achieved. Drug release profile was also studied. GPCS, therefore, could be considered to be a potential drug carrier for therapeutic treatment.
Biomedical and Environmental Applications of Chitosan-based Nanomaterials
( Jae Kweon Park ),( Lam Dai Tran ),( Hoang Vinh Tran ),( Trang Thu Mai ),( Thu Phuong Ha ),( Binh Hai Nguyen ),( Hoang Thai ),( Hoang Dinh Vu ),( Dien Gia Pham ),( Phuc Xuan Nguyen ) 한국키틴키토산학회 2011 한국키틴키토산학회지 Vol.16 No.1
Being naturally abundant resources and having many interesting physicochemical and biological properties, chitin/chitosan have been found useful in many fields. This paper describes the strategy to design a multifunctional, chitosan based nanomaterials and their biomedical and environmental applications. Different physicochemical methods including FESEM/TEM, PPMS were used to characterize the obtained nanomaterials. For each application, a series of specific characterizing methods were used for evaluating the applicability/capacity of materials.