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Nguyen, Ngoc Hung,Khan, Sheraz Ali,Kim, Cheol-Hong,Kim, Jong-Myon Elsevier 2018 Microprocessors and microsystems Vol.60 No.-
<P><B>Abstract</B></P> <P>The fast Fourier transform (FFT) algorithm is widely used in digital signal processing systems (DSPs); hence, the development of a high-performance and resource-efficient FFT processor that conforms to the processing and precision requirements of real-time signal processing is highly desirable. We propose an FFT processor for field programmable gate array (FPGA) devices, based on the radix-2-decimation-in-frequency (R2DIF) algorithm. An appropriately modified parallel double-path delay commutator (DDC) architecture for radix-2 with continuous dual-input and dual-output streams (CoDIDOS) is proposed to increase throughput and reduce latency in FFT computation. The chip-area of the proposed design is reduced by decreasing the memory footprint of the complex twiddle factor multipliers. A multiplication scheme based on a combination of the unrolled coordinate rotation digital computer (CORDIC) and the canonical signed digit-based binary expression (CSDBE) is used to multiply the complex twiddle factors without requiring memory blocks for their storage. The CSDBE technique is proposed to optimize the multiplication of constants in the architecture. The proposed FFT processor is implemented as an intellectual property (IP) core and tested on a Xilinx Virtex-7 FPGA. Experimental results confirm that the proposed design improves the speed, latency, throughput, accuracy, and resource utilization of computation on FPGA devices over existing designs.</P>
Nguyen, Ngoc Hung,Kim, Jongrok,Hong, Seung-Hyun,Moon, Sang-Ki,Song, Chul-Hwa North-Holland Pub. Co 2017 Nuclear engineering and design Vol.325 No.-
<P><B>Abstract</B></P> <P>Coolability of the partially blocked core in a large break loss-of-coolant accident (LB LOCA) is one of the most important thermal-hydraulic concerns for nuclear reactor safety analysis. During blowdown phase and early stage of reflooding phase in the LB LOCA, the prevailing wall-to-vapor convective heat transfer plays an important role on the decay heat removal process. Experiments on single-phase convective heat transfer to vapor were conducted in 5×5 heater rod bundles containing 3×3 ballooned rods of 90% flow blockage ratio with consideration of fuel relocation phenomenon. The obtained experimental data were used to assess the single-phase heat transfer enhancement models of the COBRA-TF code. The assessment results showed underprediction of local heat transfer downstream of the flow blockage. Therefore, a new correlation has been proposed to improve the prediction capability of the conventional models by more accurately describing the flow blockage effect. The new correlation predicted the local heat transfer satisfactorily within a 20% discrepancy of the experimental data for various kinds of flow blockage configurations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The wall-to-vapor convective heat transfer in partially blocked rod bundles is investigated. </LI> <LI> The COBRA-TF code underestimated local heat transfer downstream of flow blockage. </LI> <LI> A new correlation is developed to accurately describe the effect of flow blockage. </LI> <LI> Determination of reattachment point and maximum Nusselt number are critical for the new correlation. </LI> </UL> </P>
Nguyen Van Hung,Bui Thi Minh Nguyet,Nguyen Huu Nghi,Nguyen Minh Luon,Nguyen Ngoc Bich,Le Van Thanh Son,Nguyen Trung Kien,Dao Ngoc Nhiem,Nguyen Thanh Tuoi,Dinh Quang Khieu 대한환경공학회 2024 Environmental Engineering Research Vol.29 No.4
In the present work, ZnO/g-C₃N₄/biochar was prepared, and it was used for visible-light driven photocatalytic degradation of some colorants (methylene blue, rhodamine B, methyl orange) and some antibiotics (doxycycline, ciprofloxacin, amoxicilline). Biochar was prepared by pyrolysing Phragmites australis biomass. The ZnO/g-C₃N₄/biochar composite was synthesized with the alkaline hydrolysis method. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transition electron microscopy, energy dispersive X-ray/elemental mapping, ultraviolet-visible-diffuse reflectance spectroscopy, photoluminescence spectroscopy, nitrogen adsorption/desorption isotherms and X-ray photoelectron spectroscopy. The results show that ZnO nanoparticles with a large surface area are highly dispersed on the g-C₃N₄ particle surface and biochar. The composite exhibits superior photocatalytic degradation ability toward doxycycline, a broad-spectrum antibiotic of the tetracycline compared with individual components (ZnO or g-C₃N₄) and satisfies stability after six treatment cycles. The kinetics and degradation mechanisms of doxycyline were also addressed. In addition, the present catalyst also exhibits the photocatalytic degradation of methylene blue, rhodamine B, methyl orange, ciprofloxacin and amoxicillin in visible-light regions.
Nguyen Thu Hang,Nguyen Mai Chi,Nguyen Hoang Trung,Thi Y Van Tran,Vu Ngoc Trung,Thu Hang Bui,Duc Trinh Chu,Bui Tung Thanh,Jen Chun-Ping,Quang Loc Do 한국농업기계학회 2024 바이오시스템공학 Vol.49 No.1
Purpose Circulating tumor cell separation and analysis have played a critical role in cancer diagnosis, prognosis, and treatment. In this work, we aim to design and investigate a novel biochip that integrates dielectrophoresis, microfl uidic technology to separate circulating tumor cells from blood cells. To create a dielectrophoresis-induced non-uniform electric fi eld, a facing-electrode design was proposed and utilized, in which a slanted electrode array and a simple rectangular ground electrode are placed parallel on the top and bottom parts of the microfl uidic channel, respectively. This design can reduce the particle position dependence in the microchannel and the complexity of the microfabrication process. Methods The separation process, effi ciency, and optimization of the proposed device were numerically investigated using the fi nite element method. Parametric research was conducted to comprehensively examine the impact of various operating and design factors on the cell movement and trajectories in the microfl uidic device. Results The results indicated the potential of the proposed biochip to ensure cancer cell separation from blood cells with high effi ciency, high purity in a label-free, non-invasive, easy integration, and low-cost manner. Under the optimal conditions, the separation effi ciency reached 92%, 88%, and 96% for human colon cancer cells (HT-29), red blood cells, and white blood cells, respectively. Conclusions In this study, a novel DEP-based microfl uidic chip was proposed to separate HT-29 tumor cells from blood cells and numerically investigated to verify the performance of the biochip design. Our fi ndings could provide a foundation for further theoretical and practical investigations. The proposed system can separate cancer cells from red blood cells and white blood cells as well as off ers numerous advantages, such as compact size, low voltage, high effi ciency, non-invasiveness, and label-free nature. The tumor cell enrichment platform has the potential for application in cancer detection, analysis, and assessment.
AN IMPROVED HEAT TRANSFER CORRELATION FOR DEVELOPING POST-DRYOUT REGION IN VERTICAL TUBES
NGOC HUNG NGUYEN,문상기 한국원자력학회 2015 Nuclear Engineering and Technology Vol.47 No.4
A developing post-dryout region is characterized by significant heat transfer enhancements compared with the fully developed post-dryout region. The heat transfer enhancements are mainly due to upstream disturbance and entrained droplets in the region immediately downstream of the critical heat flux location. In this paper, an improved heat transfer correlation is developed for the developing post-dryout regions in vertical tubes over a wide range of flow conditions. The correlation represents a correction factor for the fully developed film-boiling look-up table to be applied to the developing post-dryout region. The new correlation significantly improves the heat transfer prediction in the developing post-dryout regions and provides very good agreement with the experimental data.
Nguyen, Hung-Ngoc,Kim, Cheol-Hong,Kim, Jong-Myon Korea Information Processing Society 2019 Journal of information processing systems Vol.15 No.2
This paper presents an optimal implementation of a Daubechies-based pipelined discrete wavelet packet transform (DWPT) processor using finite impulse response (FIR) filter banks. The feed-forward pipelined (FFP) architecture is exploited for implementation of the DWPT on the field-programmable gate array (FPGA). The proposed DWPT is based on an efficient transpose form structure, thereby reducing its computational complexity by half of the system. Moreover, the efficiency of the design is further improved by using a canonical-signed digit-based binary expression (CSDBE) and advanced functional sharing (AFS) methods. In this work, the AFS technique is proposed to optimize the convolution of FIR filter banks for DWPT decomposition, which reduces the hardware resource utilization by not requiring any embedded digital signal processing (DSP) blocks. The proposed AFS and CSDBE-based DWPT system is embedded on the Virtex-7 FPGA board for testing. The proposed design is implemented as an intellectual property (IP) logic core that can easily be integrated into DSP systems for sub-band analysis. The achieved results conclude that the proposed method is very efficient in improving hardware resource utilization while maintaining accuracy of the result of DWPT.