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Novel Techniques for Real Time Computing Critical Clearing Time SIME-B and CCS-B
Dinh, Hung Nguyen,Nguyen, Minh Y.,Yoon, Yong Tae The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.2
Real time transient stability assessment mainly depends on real-time prediction. Unfortunately, conventional techniques based on offline analysis are too slow and unreliable in complex power systems. Hence, fast and reliable stability prediction methods and simple stability criterions must be developed for real time purposes. In this paper, two new methods for real time determining critical clearing time based on clustering identification are proposed. This article is covering three main sections: (i) clustering generators and recognizing critical group; (ii) replacing the multi-machine system by a two-machine dynamic equivalent and eventually, to a one-machine-infinite-bus system; (iii) presenting a new method to predict post-fault trajectory and two simple algorithms for calculating critical clearing time, respectively established upon two different transient stability criterions. The performance is expected to figure out critical clearing time within 100ms-150ms and with an acceptable accuracy.
Nguyen, Hung Dinh,Mai, Luu,Nguyen, Hung Thanh Techno-Press 2021 Advances in concrete construction Vol.12 No.2
Self-compacting concrete used in reinforced concrete structures with high reinforcement ratios such as ports, tall buildings and bridges can bring benefits to the structures. However, the quality of self-compacting concrete is affected by climate conditions and curing methods. Climate conditions are dry and rainy seasons. Curing methods include external and internal curing. External curing by covering the surface of specimens with nylon sheet for zero hour, 4h, 6h and 24h was investigated in this study. Different amounts of lightweight sand to be able to hold water for internal curing were also examined. Results showed that with the combination of internal curing by using 20% lightweight sand to replace traditional sand and external curing by covering with nylon sheet for 24 hours, the compressive strength of self-compacting concrete in the dry season condition is higher than that of self-compacting concrete without lightweight sand ideally cured by soaking under water at laboratory condition.
NGUYEN, Xuan Hung,DANG, Thuy Quynh,DINH, Thi Thao Quyen,DO, Phuong Thanh,PHAM, Thu Uyen,MAI, Duc Duong Korea Distribution Science Association 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.6
The objective of this article is to assess the impact of corporate social responsibility (CSR) implementation on Corporate Brand Value (CBV) and Corporate Financial Performance (CFP). At the same time, the article examines the mediated role of CBV on the relationship between CSR implementation and CFP. In-depth interviews and observation techniques were used in this article on 4 experts to collect qualitative information. Quantitative analysis was based on primary data obtained from 454 employees working at enterprises providing Bancassurance services. The article uses various models of Cronbach's Alpha coefficient, Exploratory Factor Analysis (EFA), Confirmatory Factor Analysis (CFA), and Structural Equation Analysis (SEM) using SPSS 22.0 and AMOS 20.0 software. In addition, a 5-point Likert scale is used to measure observed variables. Research results show that CBV plays an intermediate role in the relationship between CSR implementation and CFP. At the same time, the implementation of CSR toward communities, customers, and workers directly impacts CBV and CFP. The article draws a new conclusion; there is no relationship found between the implementation of CSR and CFP. The result proposes implications for the state and Bancassurance service providers to develop and implement CSR-related policies and activities to enhance their brand value and financial performance.
Alumina-coated silicon-based nanowire arrays for high quality Li-ion battery anodes
Nguyen, Hung Tran,Zamfir, Mihai Robert,Duong, Loc Dinh,Lee, Young Hee,Bondavalli, Paolo,Pribat, Didier The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.47
<P>Amongst other requirements, a good anode for Li-ion battery applications must exhibit dimensional stability upon Li insertion, as well as chemical inertness with respect to the electrolyte. This latter characteristic is usually provided by the so-called solid electrolyte interphase (SEI), a passivating film that is formed at the end of the first lithiation step, originating from the partial reduction of the electrolyte and Li salt. However, silicon, which exhibits the highest known capacity for Li alloying, possesses none of the above attributes when used as an anode material. Actually, the large volume expansion of Si upon alloying with Li induces a mechanical instability of the SEI film, which therefore fails to provide its protective role. In this paper, we have studied the effect of thin alumina deposits on top of Si-based nanowires. A thin alumina deposit will act as a substitute for the SEI, preventing electrolyte decomposition. We observe that even if alumina films crack during lithiation–delithiation steps of the Si-based nanowires, they still provide some kind of protection, prolonging the lifetime of the anode. Using Al<SUB>2</SUB>O<SUB>3</SUB>-coated Si-based nanowires, we have been able to obtain a lifetime of 1280 cycles when the capacity of the anode was limited to 1200 mA h g<SUP>−1</SUP>. We also show that uncoated Si nanowires degrade more rapidly when cycled under identical conditions.</P> <P>Graphic Abstract</P><P>We have studied the effect of thin Al<SUB>2</SUB>O<SUB>3</SUB> coatings on Si-based nanowires for Li-ion battery anodes. We report a lifetime of 1280 cycles when the capacity is limited to 1200 mA h g<SUP>−1</SUP>. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm35125k'> </P>
Dinh Bang Nguyen,Thanh Phuong Dao,Hung Thuan Tran,Van Noi Nguyen,안대희,Thi Dieu Cam Nguyen 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.5
The aim of this study is to evaluate phenol degradation capability of silver modified titanium dioxide nanomaterial on bentonite support (Ag-TiO2/Bent). The material was synthesized as photocatalyst by adding Ag-TiO2 sol into bentonite suspension. The experimental results revealed that photooxidation activity of Ag-TiO2/Bent was greatly higher than that of Ag-TiO2 and TiO2/Bent. The phenol removal efficiency was 23.25%, 35.41% and 98.94% for Ag-TiO2, TiO2/Bent and Ag-TiO2/Bent, respectively. The dispersion of silver modified TiO2 on bentonite support significantly enhances photocatalytic activity under solar radiation due to surface plasmon resonance formation and prevention of anatase-to-rutile phase transformation.
A New Battery Approach to Wind Generation System in Frequency Control Market
Nguyen, Minh Y.,Nguyen, Dinh Hung,Yoon, Yong Tae The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.4
Wind power producers face many regulation costs in deregulated environment, which remarkably lowers the value of wind power in comparison with conventional sources. One of these costs is associated with the real-time variation of power output and being paid in frequency control market according to the variation band. This paper presents a new approach to coordination of battery energy storage in wind generation system for reducing the payment in frequency control market. The approach depends on the statistic data of wind generation and the prediction of frequency control market price to determine the optimal variation band which is then kept by the real-time charging and discharging of batteries, ultimately the minimum cost of frequency regulation can be obtained. The optimization problem is formulated as trade-off between the decrease in the regulation payment and the increase in the cost of using battery, and vice versus. The approach is applied to a study case and the results of simulation show its effectiveness.
Novel Techniques for Real Time Computing Critical Clearing Time SIME-B and CCS-B
Hung Nguyen Dinh,Minh Y Nguyen,Yong Tae Yoon 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.2
Real time transient stability assessment mainly depends on real-time prediction. Unfortunately, conventional techniques based on offline analysis are too slow and unreliable in complex power systems. Hence, fast and reliable stability prediction methods and simple stability criterions must be developed for real time purposes. In this paper, two new methods for real time determining critical clearing time based on clustering identification are proposed. This article is covering three main sections: (i) clustering generators and recognizing critical group; (ii) replacing the multi-machine system by a two-machine dynamic equivalent and eventually, to a one-machineinfinite-bus system; (iii) presenting a new method to predict post-fault trajectory and two simple algorithms for calculating critical clearing time, respectively established upon two different transient stability criterions. The performance is expected to figure out critical clearing time within 100ms-150ms and with an acceptable accuracy.
Hung Nguyen Dinh,Minh Y Nguyen 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.3
Recently, Korean system operating conditions have gradually approached an upper limit. When a contingency occurs, the power system may have no solutions. Different from the cases of bad initial guesses or the solutions are too close to the solvability boundary in which numerical methods can be applied, for unsolvable cases, the only way to restore solvability would be structure modifications. In this paper, a new approach for corrective and preventive control to such cases is proposed in two steps: (i) finding any solution regardless its feasibility; (ii) for the infeasible solution, make it feasible with additional modifications at load buses having Distributed Energy Resources. The test case built based on the peak load profile of 2008 by KEPCO including 1336 buses is analyzed. Since reactive power compensation is optimized to restore solvability, all demands are met, therefore no blackouts happen. The proposed method was integrated in the LP program designed by power21 Corporation.
Dinh, Hung Nguyen,Nguyen, Minh Y.,Yoon, Yong Tae The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.3
Recently, Korean system operating conditions have gradually approached an upper limit. When a contingency occurs, the power system may have no solutions. Different from the cases of bad initial guesses or the solutions are too close to the solvability boundary in which numerical methods can be applied, for unsolvable cases, the only way to restore solvability would be structure modifications. In this paper, a new approach for corrective and preventive control to such cases is proposed in two steps: (i) finding any solution regardless its feasibility; (ii) for the infeasible solution, make it feasible with additional modifications at load buses having Distributed Energy Resources. The test case built based on the peak load profile of 2008 by KEPCO including 1336 buses is analyzed. Since reactive power compensation is optimized to restore solvability, all demands are met, therefore no blackouts happen. The proposed method was integrated in the LP program designed by power21 Corporation.