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Tran Manh Tuan,Woojin Choi 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Recently wireless Power Transfer (WPT) has received a great interest due to its advantages such as better user convenience and better safety as compared to the conventional charger with cord. In a WPT charging system operating at MHz range, a DC/DC converter to provide the accurate voltage and current to the battery for its safety. This paper presents about the design and implementation of a high frequency class D Wireless Power Transfer system which makes it possible to charge the Lithium Batteries by the Constant Current (CC) and Constant Voltage (CV) Charge with a pair of coil. Since the charger can provide automatic transfer from CC to CV charge, the battery can be fully charged without the help of an additional DC/DC converter. The simulation and 50W-6.78-MHz hardware experimental results are presented to verify the feasibility of the proposed method and to evaluate the performance of the proposed wireless battery charger.
A Novel Two-Stage Power Conversion Method suitable for LDCs of the Electric Vehicles
Tran Manh Tuan,Woojin Choi 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
The Low Voltage DC-DC converters (LDCs) of the Electric Vehicles require high power density and high efficiency operation over the wide range of load and input voltage variations. This paper introduces a novel topology which combines three 1 MHz Half-Bridge (HB) LLC resonant converters and an Inverting Buck-Boost (IBB) converter to adjust the output voltage without frequency modulation. The switching frequency of the proposed converter is fixed at 1MHz to achieve a constant frequency operation for the resonant converter to achieve a maximum efficiency. In the proposed topology GaN FETs and planar transformers are employed to optimize the converter operation at high frequency. A 1 MHz/1.8 kW prototype converter is built to verify the feasibility and the validity of the proposed LDC topology.
Ha, Manh Tuan,Tran, Manh Hung,Phuong, Thien Thuong,Kim, Jeong Ah,Woo, Mi Hee,Choi, Jae Sue,Lee, Suhyun,Lee, Jeong Hyung,Lee, Hyeong Kyu,Min, Byung Sun Elsevier 2017 Bioorganic & medicinal chemistry letters Vol.27 No.13
<P><B>Abstract</B></P> <P>A phytochemical investigation into the bark of <I>Erythrophleum fordii</I> yielded four new compounds, two new cassaine diterpenoids (erythrofordin T and U, <B>1</B> and <B>2</B>) and two new cassaine diterpenoid amines (erythroformine A and B, <B>6</B> and <B>7</B>), as well as nine known compounds. We report for the first time the isolation of erythrofordin V (<B>3</B>) from a natural source and that of the remaining eight known diterpenoids (<B>4</B>–<B>5</B>, <B>8</B>–<B>13</B>) from <I>E. fordii</I>. All structures were elucidated using spectroscopic analysis. Cytotoxic activity of the isolated compounds (<B>1</B>–<B>13</B>) was examined <I>in vitro</I> against three non-small cell lung cancer cell lines (A549, NCI-H1975, and NCI-H1229) using the MTT assay. Cassaine diterpene amines (<B>6</B>–<B>10</B>, <B>12</B>, <B>13</B>) exhibited potent cytotoxic activity against all three cell lines with IC<SUB>50</SUB> values between 0.4μM and 5.9μM. Erythroformine B (<B>7</B>) significantly induced apoptosis in all three cancer cells in a concentration-dependent manner.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
LeAnh, Tuan,Tran, Nguyen H.,Saad, Walid,Le, Long Bao,Niyato, Dusit,Ho, Tai Manh,Hong, Choong Seon IEEE 2017 IEEE Transactions on Vehicular Technology VT Vol.66 No.9
<P>In this paper, a novel framework is proposed to jointly optimize user association and resource allocation in the uplink cognitive femtocell network (CFN). In the considered CFN, femtocell base stations (FBSs) are deployed to serve a set of femtocell user equipments (FUEs) by reusing subchannels used in a macrocell base station (MBS). The problem of joint user association, subchannel assignment, and power allocation is formulated as an optimization problem, in which the goal is to maximize the overall uplink throughput while guaranteeing FBSs overloading avoidance, data rate requirements of the served FUEs, and MBS protection. To solve this problem, a distributed framework based on the matching game is proposed to model and analyze the interactions between the FUEs and FBSs. Using this framework, distributed algorithms are developed to enable the CFN to make decisions about user association, subchannel allocation, and transmit power. The algorithms are then shown to converge to a stable matching and exhibit a low computational complexity. Simulation results show that the proposed approach yields a performance improvement in terms of the overall network throughput and outage probability, with a small number of iterations to converge.</P>
Tobacco Control Policies in Vietnam: Review on MPOWER Implementation Progress and Challenges
Hoang, Van Minh,Tran, Thu Ngan,Vu, Quynh Mai,Nguyen, Thi Tuyet My,Le, Hong Chung,Vu, Duy Kien,Tran, Tuan Anh,Nguyen, Bao Ngoc,Vu, Van Giap,Nguyen, Manh Cuong,Pham, Duc Manh,Kim, Bao Giang Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1
In Vietnam, the WHO Framework Convention on Tobacco Control (WHO FCTC) took effect in March 2005 while MPOWER has been implemented since 2008. This paper describes the progress and challenges of implementation of the MPOWER package in Vietnam. We can report that, in term of monitoring, Vietnam is very active in the Global Tobacco Surveillance System, completing two rounds of the Global Adult Tobacco Survey (GATS) and three rounds of the Global Youth Tobacco Survey (GYTS). To protect people from tobacco smoke, Vietnam has issued and enforced a law requiring comprehensive smoking bans at workplaces and public places since 2013. Tobacco advertising and promotion are also prohibited with the exception of points of sale displays of tobacco products. Violations come in the form of promotion girls, corporate social responsibility activities from tobacco manufacturers and packages displayed by retail vendors. Vietnam is one of the 77 countries that require pictorial health warnings to be printed on cigarette packages to warn about the danger of tobacco and the warnings have been implemented effectively. Cigarette tax is 70% of factory price which is equal to less than 45% of retail price and much lower than the recommendation of WHO. However, Vietnam is one of the very few countries that require manufacturers and importers to make "compulsory contributions" at 1-2% of the factory price of cigarettes sold in Vietnam for the establishment of a Tobacco Control Fund (TCF). The TCF is being operated well. In 2015, 67 units of 63 provinces/cities, 22 ministries and political-social organizations and 6 hospitals received funding from TCF to implement a wide range of tobacco control activities. Cessation services have been starting with a a toll-free quit-line but need to be further strengthened. In conclusion, Vietnam has constantly put efforts into the tobacco control field with high commitment from the government, scientists and activists. Though several remarkable achievements have been gained, many challenges remain. To overcome those challenges, implementation strategies that take into account the contextual factors and social determinants of tobacco use in Vietnam are needed.
Alpha-Glucosidase Inhibitory Activity of Saponins Isolated from Vernonia gratiosa Hance
Cong Pham Van,Anh Hoang Le Tuan,Vinh Le Ba,Han Yoo Kyong,Trung Nguyen Quang,Minh Bui Quang,Duc Ngo Viet,Ngoc Tran Minh,Hien Nguyen Thi Thu,Manh Hoang Duc,Lien Le Thi,Lee Ki Yong 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.6
Species belonging to the Vernonia (Asteraceae), the largest genus in the tribe Vernonieae (consisting of about 1,000 species), are widely used in food and medicine. These plants are rich sources of bioactive sesquiterpene lactones and steroid saponins, likely including many as yet undiscovered chemical components. A phytochemical investigation resulted in the separation of three new stigmastane-type steroidal saponins (1 – 3), designated as vernogratiosides A–C, from whole plants of V. gratiosa. Their structures were elucidated based on infrared spectroscopy (IR), one-dimensional (1D) and two-dimensional nuclear magnetic resonance (2D NMR), high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and electronic circular dichroism analyses (ECD), as well as chemical reactivity. Molecular docking analysis of representative saponins with αglucosidase inhibitory activity was performed. Additionally, the intended substances were tested for their ability to inhibit α-glucosidase activity in a laboratory setting. The results suggested that stigmastane-type steroidal saponins from V. gratiosa are promising candidate antidiabetic agents.