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Van Hoa Nguyen,Thi Mai Phung Bui,Thanh Phong Le,Hoang Tung Nguyen,Minh Tuyen Truong,Minh Nhut Do,Van Nha Duong 인간식물환경학회 2022 인간식물환경학회지 Vol.25 No.6
Background and objective: For countries vulnerable to climate change as Vietnam, indigenous knowledge (IK) might assist in revealing the values of local people's adaptations to environmental stresses and potentially support decision-making. Despite IK can provide the adaptive capacity of local people's activities within environmental contexts, but it is rapidly vanishing. This study aimed to describe the documentation of IK associated with climate change adaptation of farmers in the Vietnam Mekong Delta (VMD). Methods: We focused on collecting and establishing online access to IK documents through collaboration between IK holders, public sector, collecting institutions, and researchers in the five agro-ecological zones of the VMD. An online IK database for storing IK documents has been designed and implemented based on the web application schema. Results: Through interviews, we gathered IK from farming practices that are well-adapted to climate risks such as floods, droughts, and saltwater intrusions as well as traditional knowledge being used to forecast weather, flood, and saltwater intrusion. The database for storing IK documents has been successfully deployed using free and open-source software. The database currently contains more than 260 IK documents, with their location on agro-ecological zones displayed on a web-based map. Conclusion: We have captured and provided an online access to IK on climate change adaptation of the farmers in the VMD. This research is expected as an initial strategy for long-term sustainable development of the agriculture system in this region.
Van-Tung Phan,Hong-Hee Lee,Tae-Won Chun 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.6
This paper presents an effective rotor current controller for variable-speed stand-alone doubly fed induction generator (DFIG) systems feeding an unbalanced three-phase load. The proposed current controller is developed based on proportional plus two resonant regulators, which are tuned at the positive and negative slip frequencies and implemented in the rotor reference frame without decomposing the positive and negative sequence components of the measured rotor current. In addition, the behavior of the proposed controller is examined in terms of control performance and stability with respect to rotor speed variations, i.e., slip frequency variations. Simulations and experimental results are shown to validate the robustness and effectiveness of the proposed control method.
Chemical Components from the Vietnamese Soft Coral Lobophytum sp.
Tung, Nguyen Huu,Minh, Chau Van,Kiem, Phan Van,Huong, Hoang Thanh,Nam, Nguyen Hoai,Cuong, Nguyen Xuan,Quang, Tran Hong,Nhiem, Nguyen Xuan,Hyun, Jae-Hee,Kang, Hee-Kyoung,Kim, Young-Ho 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.4
Chromatographic separation resulted in the identification of one new squalene derivative, named lobophytene (1), three cembranoid diterpenes (2-4), and two sterols (5 and 6) from the Vietnamese marine soft coral Lobophytum sp. Their structures were identified on the basis of extensive spectroscopic data and comparison of those with reported data. Compounds 1 and 2 showed significant cytotoxic activities against lung (A549) and colon (HT-29) cell lines with $IC_{50}$ values of 8.2 and $5.6\;{\mu}M$ for 1; 5.1 and $1.8\;{\mu}M$ for 2, respectively.
Tung Van TRAN,Tri M. HOANG 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.4
This study examines the effect of international capital flows on corporate capital structures in Vietnam by analyzing panel data from all non-financial listed firms from 2005 to 2014 using pooled ordinary least square (OLS) with a variance estimator. The analysis includes a comparison of the signs and significance of the variable coefficients from the perking order and static trade-off theories to the empirical results to determine the optimum approach to the corporate capital structure given Vietnam’s high-inflation environment. The results indicate that international capital flows have a positive relation to the debt ratio in the long term, and the relationship is more robust for 2005–2009 than for 2010–2014. Corporate capital structures adjusted to changes in the business environment in different sub-periods (2005–2009 and 2010–2014). When the economic environment became more favorable, the pecking order theory’s predictive power increased, and that of trade-off theory lessened. Manufacturing and non-manufacturing firms required different capital structure decisions to fuel their operations and grow under foreign competition. The analysis demonstrates that firms should intensify their use of long-term debt relative to the availability of capital, which is an implication not only for firms in particular but also for industrial innovation overall.
Tung Nguyen-Thach,Nguyen Canh-Hung,Nguyen Van-Duong,Nguyen Thi-Hong-Thuy,Nguyen Van-Lam,Tran Cao-Son,Pham Thi-Minh-Hue 한국약제학회 2020 Journal of Pharmaceutical Investigation Vol.50 No.4
Purpose The study aimed firstly to determine the release behavior of the model drug (berberine chloride) from the dry coated tablets. The second objective of this study was to evaluate the exact location of the dry coated tablets in in vivo. Methods The colon targeting tablets were developed by dry powder coating technique on pan coater. The drug release behavior was determined in the three continuous mediums: pH 1.2; 7.4 and 6.8 plus pectinase. The location of the dry coated tablets in the gastrointestinal tract of human volunteers was observed through the X-ray imaging of the dry coated tablets containing the optimized radiocontrast agents. Results The release kinetics of berberine chloride from the dry coated tablets was mainly controlled by erosion and enzyme sensitive mechanism. The optimum dry coated tablets having the coating powders of pectin 102:HPMC K4 M (2:1) with the coating level of 200%, and the tablet core with BaSO4 10% and iobitridol 30% as radiocontrast agents were observed in the caecum and ascending colon of human volunteers after 5–6 h of oral administration. Conclusion The successful development of these dosage forms is believed to have a high potential in precisely monitoring the release of highly potent drugs such as anti-inflammatory drugs in bowel diseases.
Machine Fault Diagnosis and Prognosis: The State of The Art
Tung, Tran Van,Yang, Bo-Suk Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.1
Machine fault diagnostic and prognostic techniques have been the considerable subjects of condition-based maintenance system in the recent time due to the potential advantages that could be gained from reducing downtime, decreasing maintenance costs, and increasing machine availability. For the past few years, research on machine fault diagnosis and prognosis has been developing rapidly. These publications covered in the wide range of statistical approaches to model-based approaches. With the aim of synthesizing and providing the information of these researches for researcher's community, this paper attempts to summarize and classify the recent published techniques in diagnosis and prognosis of rotating machinery. Furthermore, it also discusses the opportunities as well as the challenges for conducting advance research in the field of machine prognosis.
Steamed Ginseng-Leaf Components Enhance Cytotoxic Effects on Human Leukemia HL-60 Cells
Tung, Nguyen Huu,Song, Gyu Yong,Minh, Chau Van,Kiem, Phan Van,Jin, Long Guo,Boo, Hye-Jin,Kang, Hee-Kyoung,Kim, Young Ho The Pharmaceutical Society of Japan 2010 Chemical & pharmaceutical bulletin Vol.58 No.8
<P>Three new dammarane-type glycosides, named ginsenosides SL<SUB>1</SUB>—SL<SUB>3</SUB> (<B>1</B>—<B>3</B>), and eleven known compounds (<B>4</B>—<B>14</B>) were isolated from the heat-processed leaves of <I>Panax ginseng</I>. Their structures were elucidated on the basis of extensive chemical and spectroscopic methods. Cytotoxic-activity testing of compounds <B>1</B>—<B>14</B> against human leukemia HL-60 cells showed that ginsenosides Rh<SUB>3</SUB> (<B>11</B>) and Rk<SUB>2</SUB> (<B>12</B>) exhibited potent effects with IC<SUB>50</SUB> values of 0.8 and 0.9 μ<SMALL>M</SMALL>. In addition, ginsenosides SL<SUB>3</SUB> (<B>3</B>), 20<I>S</I>-Rg<SUB>2</SUB> (<B>7</B>), F<SUB>4</SUB> (<B>10</B>), 20<I>S</I>-Rh<SUB>2</SUB> (<B>13</B>) displayed strong activity with IC<SUB>50</SUB> values of 9.0, 9.0, 7.5, and 8.2 μ<SMALL>M</SMALL>, respectively. This is the first report on chemical components of the steamed ginseng leaves.</P>
Control Strategy for Harmonic Elimination in Stand-Alone DFIG Applications With Nonlinear Loads
Van-Tung Phan,Hong-Hee Lee IEEE 2011 IEEE transactions on power electronics Vol.26 No.9
<P>This paper proposes a new control strategy of effective fifth and seventh harmonic elimination in the stator output voltage at the point of common coupling for a stand-alone doubly fed induction generator (DFIG) feeding a three-phase diode rectifier. This load regularly causes such harmonic distortions, which harmfully affect the performance of other loads connected to the DFIG. In order to allow the DFIG to deliver a pure sinusoidal stator output voltage, these harmonics must be rejected. The proposed elimination method is investigated based on the rotor current controller employing a proportional integral and a resonant controller, which is implemented in the fundamental reference frame. In this frame, both positive seventh and negative fifth voltage harmonic can be eliminated by using only single resonant compensator tuned at six multiples of synchronous frequency in the rotor current controller. The control scheme is developed in the rotor-side converter for the control and operation of the DFIG. Simulations and experimental results with 2.2-kW DFIG feeding a nonlinear load are shown to verify prominent features of the proposed control method.</P>
Data-driven approach to machine condition prognosis using least square regression tree
Van Tung Tran,양보석 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.5
Machine fault prognosis techniques have been profoundly considered in the recent time due to their substantial profit for reducing unexpected faults or unscheduled maintenance. With those techniques, the working conditions of components, the trending of fault propagation, and the time-to-failure are precisely forecasted before they reach the failure thresholds. In this work, we propose the least square regression tree (LSRT) approach, which is an extension of the classification and regression tree (CART), in association with one-step-ahead prediction of time-series forecasting techniques to predict the future machine condition. In this technique, the number of available observations is first determined by using Cao’s method and LSRT is employed as a prediction model in the next step. The proposed approach is evaluated by real data of a low methane compressor. Furthermore, a comparative study of the predicted results obtained from CART and LSRT are carried out to prove the accuracy. The predicted results show that LSRT offers the potential for machine condition prognosis.