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Vu Viet Hung,이 창 훈 배재대학교 공학연구소 2006 공학논문집 Vol.8 No.1
본 논문에서는 마이크로폰 어레이 시스템을 이용하여 여러 화자의 음성 정보로부터 각 화자가 위치한 방향을 추정하는 기술 개발 내용을 다룬다. 성능 향상을 위한 전처리 과정으로 비선형 증폭기를 사용하여 거리에 따른 영향을 최소화하는 과정과 잡음에 대한 강인성을 얻기 위해 음성활성영역을 검출하는 과정을 포함한다. 등간격으로 배치된 마이크로폰 어레이 시스템의 기하학적 특성에 따른 음원의 위치와 신호의 지연시간차이와의 상관관계로부터 화자의 위치를 역으로 추정하는 알고리즘을 기본으로 하여 가능성 척도를 계산하고 이를 활용하여 가능성이 높은 것들을 클러스터링하여 가능성이 있는 후보를 선정하여 화자의 방향을 검지한다. 이 과정에서 오인식을 최소화하기 위하여 가능성이 희박한 영역에 대한 추정 억제 방법으로 부정식 추론법을 적용하였다. 2화자의 음성 신호를 입력으로 한 실험을 통하여 제안한 방법에 의한 다화자 방향검지의 가능성을 알아보았다.
Hang Thi Thuy Vu,Viet Le Nam Vo,정영민 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.6
Untreated and sulfonated biomass-derived amorphous carbons were prepared by the pyrolysis of D-glucose at different temperatures, followed by sulfonation. Not only the surface functional group concentration but also the structure of polyaromatic carbon sheets was significantly affected by the carbonization temperature and sulfonation. More importantly, the carbonization temperature played a crucial role in determining the size of Pd nanoparticles (NPs) on glucose-derived carbons (GCx) and thereby affected the catalytic performance of Pd/GCx for the direct synthesis of hydrogen peroxide (DSHP). The volcano-shaped dependency between the Pd NP size and the carbonization temperature of GCx agrees well with the reverse relationship between the Pd NP size and the catalytic activity of Pd/ GCx. The flexible polyaromatic carbon sheet structure of the GCx was beneficial in increasing the sulfonic acid group content on the carbon surface and, therefore, H2O2 selectivity was improved in the presence of the Pd/S-GC2 catalyst (Pd supported on the sulfonated glucose-derived carbon pyrolyzed at 723 K). However, both H2 conversion and H2O2 productivity decreased over the same catalyst, possibly due to the decreased number of active sites on the clustered or single-site Pd. Reducing the catalyst resulted in a decrease in H2O2 selectivity by significantly lowering the Pd2+/Pd0 ratio and increasing the Pd NP size. These results clearly demonstrate that fine control of the physicochemical properties of the active metal and GCx support and their synergistic combination is essential to realize an efficient Pd catalyst supported on GCx for the DSHP reaction.
Nguyen, Phi-Hung,Dung, Vu Viet,Zhao, Bing Tian,Kim, Young Ho,Min, Byung Sun,Woo, Mi Hee Pharmaceutical Society of Korea 2014 Archives of Pharmacal Research Vol.37 No.11
<P>A phytochemical study of the grains of S. bicolor, resulting in the isolation of twelve flavonoid glycosides 1-12. Their chemical structures were elucidated on the basis of spectroscopic (1D and 2D NMR) and MS data analyses. All compounds were tested on thrombin time (TT) assay and α-glucosidase assay in order to assess their inhibitory effects on blood coagulation and α-glucosidase enzyme. At the concentration of 500 μg/mL, compounds 3, 4, 7 and 10 possessed the potential effects on blood coagulation with inhibitory percentage of 197, 152, 120 and 158 %, respectively, whereas aspirin, which used as a positive control, indicated 181 and 138 % inhibition at 500 and 375 μg/mL, respectively. Furthermore, compounds 3, 4, 7, 9 and 10 also displayed strong inhibitory effects on α-glucosidase enzyme, with 85.2, 55.7, 43.9, 52.7 and 65.2 % inhibition at 100 μg/mL, respectively, whereas acarbose, as a positive control, possessed only 38.7 % at the same concentration. Taken together, our data suggest that S. bicolor and its flavonoid-enrich extracts could be considered as supplemental and or functional foods having beneficial effects against blood coagulation-induced ischemia, possibly thromboembolism disease, as well as diabetes.</P>
Hoang, Quoc Viet,Rasool, Shafket,Oh, Sora,Van Vu, Doan,Kim, Da Hun,Lee, Hang Ken,Song, Chang Eun,Lee, Sang Kyu,Lee, Jong-Cheol,Moon, Sang-Jin,Shin, Won Suk Royal Society of Chemistry 2017 Journal of Materials Chemistry C Vol.5 No.31
<▼1><P>A newly synthesized small molecule donor, BDTT-2DPPBFu, is designed for incorporation into the photo-active layer in solution-processed small molecule organic photovoltaics (SM-OPVs).</P></▼1><▼2><P>A newly synthesized small molecule donor, BDTT-2DPPBFu, is designed for incorporation into the photo-active layer in solution-processed small molecule organic photovoltaics (SM-OPVs). The effects of a solvent additive (1-chloronaphthalene, CN) on the bulk heterojunction morphology of a BDTT-2DPPBFu donor:fullerene derivative acceptor (PC71BM) are investigated and correlated with the device performance. A TEM analysis revealed that the nanomorphology of the SM-OPVs evolved dramatically with increasing solvent additive volume. With an optimum concentration of 2.5 vol% CN, a nanomorphology with a fibrillar and interpenetrating network on the order of exciton diffusion length (∼10–15 nm) is formed, resulting in improvement of the short-circuit current density, fill factor, and power conversion efficiency. Further GIWAXS studies have shown that the π–π stacking distance of BDTT-2DPPBFu small molecules is reduced and the inter-mixing of PC71BM within the BDTT-2DPPBFu-rich phase in the photo-active layer processed from 2.5 vol% CN is increased, leading to enhanced charge transport and reduced charge recombination and transfer resistance. The present work provides important progress in the nanomorphology of the photo-active layer, which can be effectively tuned <I>via</I> the use of a solvent additive in SM-OPVs.</P></▼2>
NGUYEN, Phi-Hung,TSAI, Jung-Fa,NGUYEN, Viet-Trang,VU, Dang-Duong,DAO, Trong- Khoi Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.12
This paper aims to propose a Comprehensive Decision Support Model to evaluate retail companies' financial performance traded on the Vietnam Stock Exchange Market. The financial performance has been examined in terms of the valuations ratios, profitability ratios, growth rates, liquidity ratios, efficiency ratios, and leverage ratios. The data of twelve companies from the first quarter to the fourth quarter of 2019 and the first quarter of 2020 were employed. The weights of 18 chosen financial ratios are calculated by using the Standard Deviation method (SD). Grey Relational Analysis technique was applied to obtain the final ranking of each company in each quarter. The results showed that leverage ratios have the most significant impact on the retail companies' financial performance and gives some long-term investment recommendations for stakeholders and indicated that the Taseco Air Services Joint Stock Company (AST), Mobile World Investment Corporation (MWG), and Cam Ranh International Airport Services Joint Stock Company (CIA) are three of the top efficient companies. The three of the worst companies are Viglacera Corporation (VGC), Saigon General Service Corporation (SVC), and HocMon Trade Joint Stock Company (HTC). Furthermore, this study suggests that the GRA model could be implemented effectively to ranking companies of other industries in the future research.
Fully nonlinear inelastic analysis of rectangular CFST frames with semi-rigid connections
Van-Tuong Bui,Quang-Viet Vu,Viet-Hung Truong,Seung-Eock Kim 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.5
In this study, an effective numerical method is introduced for nonlinear inelastic analyses of rectangular concrete-filled steel tubular (CFST) frames for the first time. A steel-concrete composite fiber beam-column element model is developed that considers material, and geometric nonlinearities, and residual stresses. This is achieved by using stability functions combined with integration points along the element length to capture the spread of plasticity over the composite cross-section along the element length. Additionally, a multi-spring element with a zero-length is employed to model the nonlinear semi-rigid beam-to-column connections in CFST frame models. To solve the nonlinear equilibrium equations, the generalized displacement control algorithm is adopted. The accuracy of the proposed method is firstly verified by a large number of experiments of CFST members subjected to various loading conditions. Subsequently, the proposed method is applied to investigate the nonlinear inelastic behavior of rectangular CFST frames with fully rigid, semi-rigid, and hinged connections. The accuracy of the predicted results and the efficiency pertaining to the computation time of the proposed method are demonstrated in comparison with the ABAQUS software. The proposed numerical method may be efficiently utilized in practical designs for advanced analysis of the rectangular CFST structures.
Seung-Eock Kim,Quang-Viet Vu,George Papazafeiropoulos,Zhengyi Kong,Viet-Hung Truong 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.2
In this paper, the efficiency of five Machine Learning (ML) methods consisting of Deep Learning (DL), Support Vector Machine (SVM), Random Forest (RF), Decision Tree (DT), and Gradient Tree Booting (GTB) for regression and classification of the Ultimate Load Factor (ULF) of nonlinear inelastic steel frames is compared. For this purpose, a two-story, a six-story, and a twenty-story space frame are considered. An advanced nonlinear inelastic analysis is carried out for the steel frames to generate datasets for the training of the considered ML methods. In each dataset, the input variables are the geometric features of W-sections and the output variable is the ULF of the frame. The comparison between the five ML methods is made in terms of the mean-squared-error (MSE) for the regression models and the accuracy for the classification models, respectively. Moreover, the ULF distribution curve is calculated for each frame and the strength failure probability is estimated. It is found that the GTB method has the best efficiency in both regression and classification of ULF regardless of the number of training samples and the space frames considered.
Landscape Function and Tourism Industry: A Case Study of Moc Chau Plateau, Vietnam
LE, Hoa Thi Thu,TONG, Binh Thanh,VU, Ngoc Thi Minh,HO, Luu Si,PHAM, Thang Viet,TRINH, Hang Thi Thu Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.12
Tourism is not only a cultural service but also a resource consuming industry. Landscape function framework is a powerful tool to show the relationship between nature and people. This study collects 50 documents around the world to analyze the relationship between the 4 functional groups of the landscape (regulatory functions, production and supply functions, resident functions, information and entertainment functions) and the tourism industry. On that basis, we created an establishment for practical contact analysis of the goods and services of the landscape for tourism development in Moc Chau plateau, Vietnam. Research results show that tourism is an economic sector that benefits from the landscape and has a clear resource orientation. Moc Chau plateau has rich tourism resources and has the conditions to develop various types of tourism, especially cultural tourism based on community and resort tourism. The two cultural functions and the providing functions are the two most important functional groups for the tourism development of Moc Chau district, bringing the two most important tourism icons for Moc Chau, a green steppe, cool milk benevolent and also a district rich in national culture. From these conclusions, the authors give recommendations and notable points about landscapes in the tourism industry, especially in places with topography like Moc Chau.