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A High-linearity Wideband Discrete-time Receiver for Software-defined Radio
Hoai-Nam Nguyen,D. M. A. N. B. Dissanayake,Seok-Kyun Han,Sang-Gug Lee 대한전자공학회 2018 Journal of semiconductor technology and science Vol.18 No.1
A discrete-time (DT) receiver for software-defined radio (SDR) applications is presented. The receiver chain includes a wideband LNA and high linearity current commutating passive mixers merged with baseband switched-capacitor filters (SCFs) in current mode to simplify analog circuitries and reduce power consumption. An RF transconductor (RF TA) with capacitive-peaking bandwidth extension technique is proposed for the mixers to maximize the operating frequency band of the receiver. Implemented in a 0.18 μm CMOS process, the proposed receiver achieves a maximum voltage conversion gain of 41.2 dB, minimum NF of 3.8 dB, in-band IIP3 of -9 dBm, and out-of-band IIP3 of -6 dBm, respectively. The receiver operates from 0.7 to 2.4 GHz while dissipating 28-34 mA current from 1.8 V supplies.
Hoai Nam NGUYEN,김회수,Yoonjeong JO,Kevin 한국교육공학회 2015 Educational Technology International Vol.16 No.1
The purpose of this research is to propose a novel social LMS developed for group collaborative learning with a think-aloud tool integrated for sharing cognitive processes in order to improve group collaborative learning performance. In this developmental research, the system was designed with three critical elements: the think-aloud element supports learners through shared cognition, the social network element improves the quality of collaborative learning by forming a structured social environment, and the learning management element provides a understructure for collaborative learning for student groups. Moreover, the three critical elements were combined in an educational context and applied in three directions.
Application of Transcription Factor-based 3-Hydroxypropionic Acid Biosensor
Nam Hoai Nguyen,김중래,박성훈 한국생물공학회 2018 Biotechnology and Bioprocess Engineering Vol.23 No.5
Application of the recently developed wholecell 3-HP biosensor, which detects 3-hydroxypropionic acid (3-HP) and expresses fluorescence as an output signal in response to the 3-HP concentration, was studied in three areas of enzyme and metabolic engineering. First, a sensor was applied to identify active 3-hydroxyaldehyde dehydrogenase (ALDH), a key enzyme in the 3-HP production pathway. Second, with the aid of helper enzymes that catalyze the conversion of 1,3-propanediol (1,3-PDO) to 3-HP, a 3-HP biosensor was converted into a 1,3-PDO biosensor. Third, a 3-HP biosensor, with proper modifications in expression module of the output signal and the use of pH-tolerant red fluorescent protein (RFP), was shown to monitor the rate of 3-HP production under process conditions in which one or more interfering compounds are present in the culture medium and/or the medium pH decreases. This study demonstrates that 3-HP biosensors can be widely used in enzyme and metabolic engineering applications for 3-HP production.
Cooperative game-theoretic approach to traffic flow optimization for multiple intersections
Nam Bui, Khac-Hoai,Jung, Jason J. Elsevier 2018 Computers & electrical engineering Vol.71 No.-
<P><B>Abstract</B></P> <P>In this study, we focus on optimizing traffic flow at multiple intersections. Particularly, with the development of Internet of Things, intersection controllers are regarded as smart agents which can communicate and coordinate with each other. In this regard, a cooperative game theoretic approach among agents is proposed to improve traffic flow with large network. Thereby, a distributed merge and split algorithm for coalition formation is presented. This algorithm is applied to find out how to incorporate with the cooperation among agents for dynamically controlling traffic light at intersections. Furthermore, we construct a traffic simulation framework to evaluate our approach. With various parameters for traffic density, our proposed system can effectively improve traffic flow in both uniform and non-uniform. In particular, by coordinating among controllers, the waiting time of vehicles at intersections can be reduced from 15% to 25% comparing with previous methods (e.g., Green Wave Coordination).</P>
Development of Biosensor for 3-Hydroxypropionic Acid
Nam Hoai Nguyen,Jung Rae Kim,SUNGHOON PARK 한국생물공학회 2019 Biotechnology and Bioprocess Engineering Vol.24 No.1
In this study, whole-cell biosensors that detect and indicate the concentration of 3-hydroxypropionic acid (3-HP) by producing a green fluorescent signal were developed using a transcription factor (TF)-responsive 3- HP inducible promoter identified in the Pseudomonas denitrificans 3-HP degradation pathway. Upon forming a complex with 3-HP, the MmsR TF protein, a LysR-type transcriptional regulator (LTTR), binds to the PmmsA promoter and controls the expression of the PmmsA-regulated gfp reporter gene in response to the concentration of 3-HP. Furthermore, by enhancing the expression of MmsR and through mutagenesis of the PmmsA promoter region, three well-performing biosensors were developed that covered a wide dynamic range of 3-HP (0.01-100 mM when added externally) with ~100-fold signal change upon induction in P. denitrificans. The 3-HP biosensor machinery, composed of MmsR, the PmmsA promoter and gfp could also function well in E. coli and P. putida. The developed 3-HP biosensors should be useful for engineering 3-HP-producing strains and the enzymes associated with its production.
Neutronics design of VVER-1000 fuel assembly with burnable poison particles
Hoai-Nam Tran,Van-Khanh Hoang,Peng Hong Liem,Hung T.P. Hoang 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.7
This paper presents neutronics design of VVER-1000 fuel assembly using burnable poison particles (BPPs) for controlling excess reactivity and pin-wise power distribution. The advantage of using BPPs is that the thermal conductivity of BPP-dispersed fuel pin could be improved. Numerical calculations have been conducted for optimizing the BPP parameters using the MVP code and the JENDL-3.3 data library. The results show that by using Gd2O3 particles with the diameter of 60 and the packing fraction of 5%, the burnup reactivity curve and pin-wise power distribution are obtained approximately that of the reference design. To minimize power peaking factor (PPF), total BP amount has been distributed in a larger number of fuel rods. Optimization has been conducted for the number of BPP-dispersed rods, their distribution, BPP diameter and packing fraction. Two models of assembly consisting of 18 BPP-dispersed rods have been selected. The diameter of 300 and the packing fraction of 3.33% were determined so that the burnup reactivity curve is approximate that of the reference one, while the PPF can be decreased from 1.167 to 1.105 and 1.113, respectively. Application of BPPs for compensating the reduction of soluble boron content to 50% and 0% is also investigated.