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.

A New Battery Approach to Wind Generation System in Frequency Control Market

Minh Y Nguyen,Dinh Hung Nguyen,Yong Tae Yoon 대한전기학회 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.

Experimental evidence of breakdown strength and its effect on energystorage performance in normal and relaxor ferroelectric films

Minh D. Nguyen,Chi T.Q. Nguyen,Hung N. Vu,Guus Rijnders 한국물리학회 2019 Current Applied Physics Vol.19 No.9

Normal-ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) and relaxor-ferroelectric Pb0.9La0.1(Zr0.52Ti0.48)O3 (PLZT) thinfilms are deposited on SrRuO3-covered SrTiO3/Si substrates. An ultrahigh recoverable energy-storage density (Ureco) of 68.2 J/cm3 and energy efficiency (η) of 80.4% are achieved in the PLZT thin-films under a large breakdown strength (EBD) of 3600 kV/cm. These values are much lower in the PZT thin-films (Ureco of 10.3 J/ cm3 and η of 62.4% at EBD of 1000 kV/cm). In addition, the remanent polarization (Pr) and dielectric-constant are also investigated to evaluate the breakdown strength in thin-films. Polar nano-regions (PNRs) are created in the PLZT thin-films to enable relaxor behavior and lead to slim polarization loops along with very small Pr. The excellent operating temperature of energy-storage performance and also the breakdown strength obtained in the PLZT thin-films are mainly ascribed to the presence of PNRs. Moreover, both PZT and PLZT thin-films exhibit superior performance up to 1010 times of charge-discharge cycling.

A Study on the Poverty of Mountain People Depending on Forests

NGUYEN, Phuong Thi Minh,NGUYEN, Song Van,DO, Duc Tai,NGUYEN, Quynh Thi Thuy,DINH, Thanh Trung,NGUYEN, Hang Phan Thu Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.7

Livelihood capitals have a clear influence on livelihood development. As for the livelihood results, it has been pointed out in the analysis of the poor households that the ability of people to escape poverty depends especially on the access to livelihood capitals. This study aims to analyze the impacts of livelihood capital on poverty among mountain people who depend on forests through human capital, social capital, natural capital, physical capital and financial capital. This research employs the model of binary regression function. Independent variables x1, x2, …, xn are targets of livelihood strategy, vulnerability context, and livelihood capitals. These variables were selected to be included in the original model with dependent variable Y as poor and non-poor households. This study surveys households living in upland areas, near forests, and households of ethnic minorities. The results show that,out of the poor household rate, nearly 4% are newly-poor households or those falling back into poverty. Therefore, the government needs to pay more attention to this disadvantaged group and implements policies such as education and training policies, credit support policies, policies to support forest development, and payment for forest environmental services in the context of emerging countries like Vietnam.

A New Approach for Corrective and Preventive Control to Unsolvable Case in Power Networks having DERs

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.

The Hedonic Method in Evaluating Apartment Price: A Case of Ho Chi Minh City, Vietnam

NGUYEN, Ha Minh,PHAN, Hung Quoc,TRAN, Tri Van,TRAN, Thang Kiem Viet Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.6

The study examines factors affecting apartment prices in the real estate market of Ho Chi Minh City, Vietnam. The study uses primary data based on surveys of customers who have traded successfully, and collects transaction data from real estate trading companies that are the top investors in Ho Chi Minh City real estate market. The collected data include 384 observations in a total of 24 districts, detailing that each district surveyed on a minimum of four projects, each project carried out a survey on a minimum of four apartments. The survey collected 339 valid questionnaires for analysis and model testing. This study employs multivariate regression with the data of 339 observations. The research results reveal that five significant factors affect positively the price of apartments in Ho Chi Minh City - apartment area, toilet and bedroom, apartment floor, reference price, and apartment interior. Besides, there are three significant factors affecting negatively the price of apartments - next price trend, distance to city center, and potential building. From the results, the research proposes solutions in the pricing of apartments in the real estate market in Ho Chi Minh City - better information system, a real estate transaction index, and stricter management of small brokerage activities.

Triterpenoid saponins from the roots of Rosa rugosa Thunb. as rat intestinal sucrase inhibitors

Nguyen Phuong Thao,Bui Thi Thuy Luyen,주성호,Tran Manh Hung,Nguyen Xuan Cuong,Nguyen Hoai Nam,권영인,Chau Van Minh,김영호 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.10

Medicinal plants constitute an important sourceof potential therapeutic agents for diabetes. The purpose ofpresent study is to investigate the effect of root extract ofRosa rugosa Thunb. on inhibition of sucrase related todiabetes mellitus (DM). Bioassay-guided fractionation ofthe methanol extract led to the identification of 13 triterpenoidsaponins (1–13). Their structures were elucidatedon the basis of extensive spectroscopic analysis, including1D, 2D NMR, and MS. The n-butanol fraction showedpotent rat intestinal sucrase inhibitory activity with value of87.62 ± 5.84 % inhibition compared to the positive controlacarbose (50.96 ± 2.97 % inhibition at 0.02 mM). Subsequently, compounds 11–13 (1.0 mM) exhibited significantsucrase inhibitory activity, with inhibition percentagevalues of 41.17 ± 3.52, 46.80 ± 4.00, and39.39 ± 4.19 %, respectively. Whereas, compounds 2–6,8, and 10 showed moderate sucrase inhibitory activity(ranging from 13.26 ± 7.00 to 32.08 ± 6.04 % inhibition)at a same concentration. The data provide a starting pointfor creating new sucrase inhibitors, which may be usefulfor the development of effective therapies for the treatmentof DM.

Visible light-driven photocatalytic degradation of doxycycline using ZnO/g-C₃N₄/biochar composite in aqueous solution

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.

Fiscal Decentralization, Corruption, and Income Inequality: Evidence from Vietnam

Hung Thanh NGUYEN,Thuy Hoang Ngoc VO,Duc Doan Minh LE,Vu Thanh NGUYEN 한국유통과학회 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.11

The objective of this research paper is to study the simultaneous relationship between fiscal decentralization, corruption, and income inequality among Vietnamese provinces. We use a balanced panel data set of 63 provinces/cities in Vietnam in the period from 2011 to 2018. The study used 3SLS-GMM (Three Stage Least Squares - Generalized Method of Moments estimator) and GMM-HAC (Generalized Method of Moments - Heteroskedastic and Autocorrelation Consistent estimator). Empirical evidence shows a strong simultaneous relationship: increased corruption will increase regional income disparities, income inequality, and increase fiscal decentralization. In addition, the results also suggest that an increase in per-capita income will reduce the level of corruption, or better control corruption of each province. The degree of increase in income inequality, which reduces fiscal decentralization, is the same for trade liberalization. All demonstrate that there is a simultaneous relationship between fiscal decentralization, corruption, and income inequality. In a region of high public governance quality, fiscal decentralization positively effects its economic growth. This issue will indirectly increase income inequality between provinces within a country. Our findings imply that a country’s fiscal decentralization strategy should be linked to improving corruption control and local governance effectiveness, indirectly improving income inequality between localities or regions.

분산전원의 특성을 고려한 조류계산의 새로운 알고리즘 고찰

Nguyen Dinh Hung,Nguyen Minh Y,Nguyen Van Thang,김태원(Tae Won Kim),김건중(Kern Joong Kim),윤용태(Yong Tae Yoon) 대한전기학회 2011 대한전기학회 학술대회 논문집 Vol.2011 No.7