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Binh Hai Nguyen,Binh Thanh Nguyen,Hanh Van Vu,Chuc Van Nguyen,Dzung Tuan Nguyen,Loc Thai Nguyen,Thu Thi Vu,Lam Dai Tran 한국물리학회 2016 Current Applied Physics Vol.16 No.2
In this work, a lactose biosensor was developed by co-immobilizing b-galactosidase (b-Gal) and glucose oxidase (GOx) on microelectrodes pre-modified with Pt/graphene/P(1,5-DAN) for estimation of lactose in dairy products to prevent lactose intolerance. The Pt microelectrode was modified with graphene and 1,5-polydiaminonaphthalene film. Graphene was synthesized by chemical vapor deposition on copper tape and manually transferred to the electrode surface. Polymeric P(1,5-DAN) was grafted on top of the graphene film by electropolymerization. Modified surface of the electrode was characterized by Raman spectra analysis, FE-SEM, AFM and cyclic voltammetry. The results indicated that deposition graphene film on electrode surface induced considerable enhancement in current signal, over 20 times as high as the uncoated electrode surface. The developed sensor was successfully used to determine lactose in model samples with sensitivity, correlation coefficient (R2) and limit of detection (LOD) estimated to be 1.33 mA/(mgml1), 0.995 and 1.3 mg/ml, respectively. The combined graphene and conductive P(1,5-DAN) could serve as a novel sensing platform on electrochemical sensors with superior sensitivity.
Truong Giang Nguyen,Thanh Khiem Nguyen,Ham Hoi Nguyen,Hong Son Trinh,Tuan Hiep Luong,Minh Trong Nguyen,Van Duy Le,Hai Dang Do,Kieu Hung Nguyen,Van Minh Do,Quang Huy Tran,Cuong Thinh Nguyen 한국간담췌외과학회 2024 Annals of hepato-biliary-pancreatic surgery Vol.28 No.1
Backgrounds/Aims: Parenchymal-sparing anatomical hepatectomy (Ps–AH) based on portal ramification of the right anterior section (RAS) is a new technique to avoid unnecessarily transecting too much liver parenchyma, especially in cases of major anatomical hepatectomy. Methods: We prospectively assessed 26 patients with primary hepatic malignancies having undergone major Ps–AH based on portal ramification of the RAS from August 2018 to August 2022 (48 months). The perioperative indications, clinical data, intra-operative index, pathological postoperative specimens, postoperative complications, and follow-up results were retrospectively evaluated. Results: Among the 26 patients analyzed, there was just one case that had intrahepatic cholangiocarcinoma The preoperative level of α– Fetoprotein was 25.2 ng/mL. All cases (100%) had Child–Pugh A liver function preoperatively. The ventral/dorsal RAS was preserved in 19 and 7 patients, respectively. The mean surgical margin was 6.2 mm. The mean surgical time was 228.5 minutes, while the mean blood loss was 255 mL. In pathology, 5 cases (19.2%) had microvascular invasion, and in the group of HCC patients, 92% of all cases had moderate or poor tumor differentiation. Six cases (23.1%) of postoperative complications were graded over III according to the Clavien–Dindo system, including in three patients resistant ascites or intra-abdominal abscess that required intervention. Conclusions: Parenchymal-sparing anatomical hepatectomy based on portal ramification of the RAS to achieve R0-resection was safe and effective, with favorable short-term outcomes. This technique can be used widely in clinical practice.
Huynh Le Thanh Nguyen,Tran Thanh Nhut,Ho Thi Thanh Nguyen,Le Xuan Hoa,Le Viet Hai,Nguyen Thai Hoang 한국탄소학회 2022 Carbon Letters Vol.32 No.6
Enhancing the capacitive deionization performance requires the inner structure expansion of porous activated carbon to facilitate the charge storage and electrolyte penetration. This work aimed to modify the porosity of coconut-shell activated carbon (AC) through CO2 activation at high temperature. The electrochemical performance of CO2-activated AC electrodes was evaluated by cyclic voltammetry, charge/discharge test and electrochemical impedance spectroscopy, which exhibited that AC-800 had the superior performance with the highest capacitance of 112 F/g at the rate of 0.1 A/g and could operate for up to 4000 cycles. Furthermore, in the capacitive deionization, AC-800 showed salt removal of 9.15 mg/g with a high absorption rate of 2.8 mg/g min and Ni(II) removal of 5.32 mg/g with a rate close to 1 mg/g.min. The results promote the potential application of CO2-activated AC for desalination as well as Ni-removal through capacitance deionization (CDI) technology.
Thanh Hai Nguyen,Dong-Choon Lee 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper proposes a new control scheme of a vector-controlled induction machine (IM) drives in overmodulation range to maximize the voltage utilization of the voltage-source inverter. For an operation in overmodulation region, a modified voltage reference is generated for the space-vector pulsewidth modulation (SVPWM). The harmonic current components in the feedback currents needs to be eliminated before feeding to the PI current controllers to improve the control performance. The response of PI current controllers in overmodulation range has been analyzed. A composite observer is applied to estimate the harmonic components of the currents, which is good performance without delay compared with the measured currents. The proposed method has been verified by simulation results.
Ride-Through Technique for PMSG Wind Turbines using Energy Storage Systems
Nguyen, Thanh Hai,Lee, Dong-Choon The Korean Institute of Power Electronics 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.6
This paper deals with a ride-through technique for permanent-magnet synchronous generator (PMSG) wind turbine systems using energy storage systems (ESS). A control strategy which consists of current and power control loops for the energy storage systems is proposed. By increasing the generator speed, some portion of the turbine power can be stored in the system inertia. Therefore, the required energy capacity of the ESS can be decreased, which results in a low-cost system. In addition, the power fluctuations due to wind speed variations can be smoothened by controlling the ESS appropriately. The effectiveness of the proposed method is verified not only by the simulation results for a 2[MW] PMSG wind turbine system, but also by the experiment results for a reduced-scale turbine simulator.
Order-Preserving Condensation of Moving Objects in Surveillance Videos
Nguyen, Hai Thanh,Jung, Seung-Won,Won, Chee Sun IEEE 2016 IEEE transactions on intelligent transportation sy Vol.17 No.9
<P>Vision-based detection of illegal or accidental activities in urban traffic has attracted great interest. Since state-of-the-art online automated detection algorithms are far from perfect, much research effort on offline video surveillance has been made to prevent police or security staff from observing all recorded video frames unnecessarily. To solve the problem, this study focuses on video condensation, which provides fast monitoring of moving objects in a long duration of surveillance videos. Considering the computational complexity and the condensation ratio as the two main criteria for efficient video condensation, we propose a video condensation algorithm, which consists of the following: 1) initial condensation by discarding frames of nonmoving objects; 2) intra-GoFM (group of frames with moving objects) condensation; and 3) inter-GoFM condensation. In the intra-GoFM and inter-GoFM condensation, spatiotemporal static pixels within each GoFM and temporal static pixels between two consecutive GoFMs are dropped to shorten the temporal distances between consecutive moving objects. Experimental results show that our video condensation saves a significant amount of computational loads compared with the previous methods without sacrificing the condensation ratio and visual quality.</P>
Improving Utilization of GPS Data for Urban Traffic Applications
Nguyen Duc Hai,Nguyen Tan Phuc,Doan Khue,Ta Ho Thai Hai,Pham Tran Vu,Huynh Nam,Le Thanh Van 한국인터넷방송통신학회 2015 International Journal of Internet, Broadcasting an Vol.7 No.1
The use of Intelligent Transportation System (ITS) is promising to bring better solutions for managing and handling the city traffic. This system combines many fields in advanced technology such as Global Positioning System (GPS), Geographic Information System (GIS) and so on. The basement of applications in ITS is the effective collections and data integration tools. The purpose of our research is to propose solutions which involve the use of GPS time series data collected from GPS devices in order to improve the quality of output traffic data. In this study, GPS data is collected from devices attached to vehicles travelling on routes in Ho Chi Minh City (HCMC). Then, GPS data is stored in database system to serve in many transportation applications. The proposed method combines the data usage level and data coverage to improve the quality of traffic data.
Improved LVRT Capability and Power Smoothening of DFIG Wind Turbine Systems
Nguyen, Thanh Hai,Lee, Dong-Choon The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.4
This paper proposes an application of energy storage devices (ESD) for low-voltage ride-through (LVRT) capability enhancement and power smoothening of doubly-fed induction generator (DFIG) wind turbine systems. A grid-side converter (GSC) is used to maintain the DC-link voltage. Meanwhile, a machine-side converter (MSC) is used to control the active and reactive powers independently. For grid disturbances, the generator output power can be reduced by increasing the generator speed, resulting in an increased inertial energy of the rotational body. Design and control techniques for the energy storage devices are introduced, which consist of current and power control loops. Also, the output power fluctuation of the generator due to wind speed variations can be smoothened by controlling the ESD. The validity of the proposed method has been verified by PSCAD/EMTDC simulation results for a 2 MW DFIG wind turbine system and by experimental results for a small-scale wind turbine simulator.
Nguyen, Thanh Hai,Van, Tan Luong,Lee, Dong-Choon,Park, Joo-Hong,Hwang, Joon-Hyeon The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.6
This paper proposes a control mode switching scheme between vector control and constant V/f control for induction machine (IM) drives for maximum torque utilization in a higher speed region. For the constant V/f scheme, a smooth transition method from the linear range of PWM up to the six-step mode is applied, by which the machine flux and torque can be kept constant in a high-speed range. Also, a careful consideration of the initial phase angle of the voltage in the transient state of the control mode change between the vector control and V/f schemes is described. The validity of the proposed strategy is verified by the experiment result for a 3-kW induction motor drives.
Magnetocaloric Effect in Fe-Ni-Zr Alloys Prepared by Using the Rapidly-quenched Method
Nguyen Huy Dan,Nguyen Huu Duc,Tran Dang Thanh,Nguyen Hai Yen,Ngac An Bang,Do Thi Kim Anh,판더롱,유성초 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
Fe90−xNixZr10 (x = 0, 5, 10, 15, 20 and 25) ribbons with various thicknesses were prepared byusing a melt-spinning technique. The Curie temperature, TC, of the alloys dramatically decreasedfrom 960 K to room temperature at high quenching rates. When the alloys had an amorphousstructure, their TC strongly depended on the Ni concentration. The maximum entropy change,|Sm|max, with H = 12 kOe, of the alloys was around 1 J·kg−1K−1 at room temperature. Onthe other hand, the full width at half maximum the entropy-change peak was quite large, 85 K,which was suitable for applications in magnetic refrigerators at room temperature.