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Two new species of Camellia (Theaceae) from Vietnam
Lieu Thi Nguyen,Ninh Tran,Uematsu CHIYOMI,Katayama HIRONORI,Dung Van Luong,Son Thanh Hoang,Ky Danh NGUYEN,Hung Viet NGUYEN,Toan Canh THAI 한국식물분류학회 2018 식물 분류학회지 Vol.48 No.2
Two new species of Camellia (Theaceae) are described from Vietnam: Camellia vuquangensis Luong, Tran & L. T. Nguyen and Camellia hatinhensis Luong, Tran & L. T. Nguyen. The new taxa were col- lected from Vu Quang National Park in the center of Vietnam. The new finds are morphologically dissimilar to all known Camellia species. Recent Camellia discoveries have increased the number of species recorded in Viet- nam from 50 to 75, making Vietnam a center of diversity and a crucial area for more research into the diversity and distributions of Camellia.
Experiment on Nearest Level Modulation algorithm for FPGA based Modular Multilevel Converters
Tran Hung Cuong,Pham Viet Phuong,Tran Van Phuong,Tran Trong Minh 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Modular Multilevel Converters (MMC) have many advantages in comparison with conventional multilevel converters in application to high voltage system. However, the control system of MMC requires a large amount of I/O signal ports which cannot be generated by a single digital signal processor (DSP) with maximum I/O port of 24. This paper fucuses on the experimental results of aMMC that uses a Field Programmable Gate Array (FPGA) in which embedge the Nearest Level Modulation (NLM) method and capacitor voltage balancing algorithm. The MMC consists of 12 Sub-Modules (SM) in each phase to generate a 13-level ac output voltage. Applying the NLM method and capacitor voltage balancing algorithm have significantly reduced the switching frequency and produced an ac output voltage with very low harmonic distortion. The experimental results have verified by a laboratory-scale prototype and compared with the simulation results.
Viet Hung Pham,정진석,Thanh Truong Dang,Tran Viet Cuong,Seung Hyun Hur,Byung-Seon Kong,김의정 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.5
We report the effect of temperature on the extent of graphene oxide reduction by hydrazine and the dispersibility of the resulting chemically converted graphene (CCG) in polar organic solvents. The extent of graphene oxide reduction at high temperatures was only slightly higher than at low temperatures (30-50 oC), while the dispersibility of the resulting CCG in organic solvents decreased markedly with increasing temperature. The low dispersibility of CCGs prepared at high temperatures was greatly affected by reduction and influenced by the formation of an irreversible agglomerate of CCG at high temperatures. The reduction of graphene oxide at low temperatures is necessary to prepare highly dispersible CCG in organic solvents. CCG prepared at 30 oC is dispersible in N-methyl-2-pyrrolidone concentrations as high as 0.71 mg/mL. The free-standing paper made of this CCG possessed an electrical conductivity of more than 22,000 S/m, one of the highest values ever reported.
Graphitic g-C3N4-WO3 Composite: Synthesis and Photocatalytic Properties
An Tran Doan,Xuan Dieu Nguyen Thi,Phi Hung Nguyen,Viet Nga Nguyen Thi,김성진,Vien Vo 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.6
Graphitic g-C3N4-WO3 composite was synthesized simply by decomposing melamine in the presence of WO3 at 500 oC. The obtained material was characterized by XRD, SEM, IR and XPS. The results showed that the as-prepared composite exhibits orthorhombic WO3 phase coated by g-C3N4 and the g-C3N4 decomposed completely with N-doped WO3 remaining at elevated calcination temperatures. The photocatalytic activity of the composite was evaluated by the photodegradation of methylene blue under visible light. An enhancement in photocatalytic activity for the graphitic g-C3N4-WO3 composite compared to the conventional nitrogendoped WO3 was observed, which can be attributed to the presence of g-C3N4 in the material.
Travel Intention to Visit Tourism Destinations: A Perspective of Generation Z in Vietnam
NGUYEN, Viet Hoang,TRUONG, Thi Xuan Dao,PHAM, Huong Trang,TRAN, Duc Thanh,NGUYEN, Pham Hung Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.2
The purpose of this research is to investigate the impacts of gen-Z's perception of consumer-generated content on social media on their travel intention with the mediating role of travel motivation push and pull. An online questionnaire survey of a total of 369 samples was conducted with the participation of gen Z in the most important cities across Vietnam. The model was analyzed using Structural Equation Modeling (SEM) using AMOS program 22 to investigate model relationships and all hypotheses are significant. The findings indicated that gen Z values the usefulness of social media and they use social media for knowledge-seeking (push factor), and this leads to their intention to visit a destination. SEM analysis also reveals that gen Z tends to use social media to find accessibility to any destinations and they are motivated highly with destinations that have clear and easy access, for example, no visa requirement or neighboring destinations. As the result, they have better intentions to visit these destinations. This research will help marketers, especially marketing specialists to gain a better understanding of gen Z, thus implement better marketing techniques to target gen Z.
A Novel Heuristic Algorithm for Online 3D Bin Packing
Thanh-Hung Nguyen,Viet-Thang Tran,Phan-Quan Doan,Thi-Thoa Mac 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
The paper presents a novel heuristic algorithm to solve the problem of automatically packing 3-dimensional boxes into containers. In this application, the collection of boxes is unknown, and a box must be packed immediately before the next box appears. The algorithm is developed based on the main and secondary data systems. The main data system describes the spaces that are large enough to fit a box. The secondary data system describes the small spaces that cannot accommodate boxes. The search algorithm based on these two data systems allows to reduce the workload of searching and is convenient in organizing and editing data systems. Experimental results show that this method is superior in terms of processing speed and packed volume ratio.
Sy Hung Mai,Viet-Linh Tran,Duy-Duan Nguyen,Viet Tiep Nguyen,Duc-Kien Thai 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.2
This paper proposes a hybrid machine-learning model, which is called DANN-IP, that combines a deep artificial neural network (DANN) and an interior-point (IP) algorithm in order to improve the prediction capacity on the patch loading resistance of steel plate girders. For this purpose, 394 steel plate girders that were subjected to patch loading were tested in order to construct the DANN-IP model. Firstly, several DANN models were developed in order to establish the relationship between the patch loading resistance and the web panel length, the web height, the web thickness, the flange width, the flange thickness, the applied load length, the web yield strength, and the flange yield strength of steel plate girders. Accordingly, the best DANN model was chosen based on three performance indices, which included the R^2, RMSE, and a20-index. The IP algorithm was then adopted to optimize the weights and biases of the DANN model in order to establish the hybrid DANN-IP model. The results obtained from the proposed DANN-IP model were compared with of the results from the DANN model and the existing empirical formulas. The comparison showed that the proposed DANN-IP model achieved the best accuracy with an R^2 of 0.996, an RMSE of 23.260 kN, and an a20-index of 0.891. Finally, a Graphical User Interface (GUI) tool was developed in order to effectively use the proposed DANN-IP model for practical applications.
유대황,Tran Viet Cuong,Viet Hung Pham,정진석,Nguyen Tri Khoa,김의정,한성홍 한국물리학회 2011 Current Applied Physics Vol.11 No.3
Photocatalytic TiO_2 films were prepared using RF magnetron sputtering and three kinds of graphene oxide (GO) solutions with different concentration of 0.05 mg GO, 0.03 mg GO, and 0.01 mg GO in 10 ml ethanol were coated on TiO_2 films, respectively. Structures and morphologies of the samples were examined by AFM, SEM, and Raman and photocatalytic properties under UV and visible irradiation were examined respectively. The efficiency of the photodegradation is enhanced when TiO_2 thin film was coated with GO, it is related to its giant π-conjugation system and two-dimensional planar structure and efficient charge separation by coating GO. The maximum photodegradation rate was observed for TiO_2thin film coated with 0.03 mg GO. It is attributed to the increase of absorbance and scattering of photons through excess carbon in the photosystem.