A study on modeling of a hybrid wind wave energy converter system

Tri Dung Dang,Cong Binh Phan,Hoai Vu Anh Truong,Chau Duy Le,Minh Tri Nguyen,Kyoung-Kwan Ahn 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

A model of a hybrid wind wave energy converter (HWWEC) system is proposed in this paper. The HWWEC includes two wave buoys and a vertical axis wind turbine (VAWT) system, which co-works to drive a generator. Wave buoys are arranged in an arc pattern to capture efficiently wave energy from many directions. The hydrodynamic forces are calculated by the Wave Analysis at Massachusetts Institute of Technology WAMIT software. In order to bring the system into resonance with the incident wave frequencies, a variable inertia hydraulic flywheel is employed so that the power output is maximized. Specifications and working principle of the whole system are presented and described. WEC unit model and hybrid mechanism are also presented. Simulations are carried out to evaluate the performance the HWWEC with the given specifications. Then, simulation results under some phase differences are taken to investigate the influence on the overall efficiency.

Design, Modeling and Analysis of a PEM Fuel Cell Excavator with Supercapacitor/Battery Hybrid Power Source

Tri Dung Dang,Tri Cuong Do,Hoai Vu Anh Truong,Cong Minh Ho,Hoang Vu Dao,YU YINGXIAO,정은진,안경관 사단법인 유공압건설기계학회 2019 드라이브·컨트롤 Vol.16 No.1

The objective of this study was to design and model the PEM fuel cell excavator with supercapacitor/battery hybrid power source to increase efficiency as well as eliminate greenhouse gas emission. With this configuration, the system can get rid of the internal combustion engine, which has a low efficiency and high emission. For the analysis and simulation, the governing equations of the PEM system, the supercapacitor and battery were derived. These simulations were performed in MATLAB/Simulink environment. The hydraulic modeling of the excavator was also presented, and its model implemented in AMESim and studied. The whole system model was built in a co-simulation environment, which is a combination of MATLAB/Simulink and AMESim software. The simulation results were presented to show the performance of the system.

Design, Modeling and Analysis of a PEM Fuel Cell Excavator with Supercapacitor/Battery Hybrid Power Source

Dang, Tri Dung,Do, Tri Cuong,Truong, Hoai Vu Anh,Ho, Cong Minh,Dao, Hoang Vu,Xiao, Yu Ying,Jeong, EunJin,Ahn, Kyoung Kwan The Korean Society for Fluid Power and Constructio 2019 드라이브·컨트롤 Vol.16 No.1

The objective of this study was to design and model the PEM fuel cell excavator with supercapacitor/battery hybrid power source to increase efficiency as well as eliminate greenhouse gas emission. With this configuration, the system can get rid of the internal combustion engine, which has a low efficiency and high emission. For the analysis and simulation, the governing equations of the PEM system, the supercapacitor and battery were derived. These simulations were performed in MATLAB/Simulink environment. The hydraulic modeling of the excavator was also presented, and its model implemented in AMESim and studied. The whole system model was built in a co-simulation environment, which is a combination of MATLAB/Simulink and AMESim software. The simulation results were presented to show the performance of the system.

Determinants of Liquidity in Manufacturing Firms

VU, Thu Minh Thi,TRUONG, Tu Van,DINH, Dung Thuy Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.12

This study examines the factors that affect firm's liquidity in manufacturing companies listed in Vietnam. Factors studied include the board size, the board independence, the firm size, the firm age, and its return. We use different metrics to measure firm's solvency status, including the cash ratio, the quick ratio, and the cash conversion cycle. Accordingly, three econometric models are built to test hypotheses proposed by researchers in order to explain the relationship between the five factors above and liquidity's measures. The study used the data set of manufacturing companies listed on the Ho Chi Minh City Stock Exchange in the period from 2015 to 2019. The final sample group comprises 139 firms with 633 observations. The results show that in manufacturing firms, while the cash ratio and the quick ratio are positively associated to the board size, the board independence, and the firm's profitability, the net operating cycle is negatively correlated to the board size, the firm size, the board independence, and the profitability. Therefore, larger firms with larger board size and more independent members can help to improve capital management efficiency.There is no evidence for the relationship between the firm age and solvency measurements, between cash conversion cycle and firm's profitability.

A novel control method to maximize the energy-harvesting capability of an adjustable slope angle wave energy converter

Tri, Nguyen Minh,Truong, Dinh Quang,Thinh, Do Hoang,Binh, Phan Cong,Dung, Dang Tri,Lee, Seyoung,Park, Hyung Gyu,Ahn, Kyoung Kwan Elsevier 2016 RENEWABLE ENERGY Vol.97 No.-

<P><B>Abstract</B></P> <P>This paper introduces a novel control approach to maximizing the output energy of an adjustable slope angle wave energy converter (ASAWEC) with oil-hydraulic power take-off. Different from typical floating-buoy WECs, the ASAWEC is capable of capturing wave energy from both heave and surge modes of wave motions. For different waves, online determination of the titling angle plays a significant role in optimizing the overall efficiency of the ASAWEC. To enhance this task, the proposed method was developed based on a learning vector quantitative neural network (LVQNN) algorithm. First, the LVQNN-based supervisor controller detects wave conditions and directly produces the optimal titling angles. Second, a so-called efficiency optimization mechanism (EOM) with a secondary controller was designed to regulate automatically the ASAWEC slope angle to the desired value sent from the supervisor controller. A prototype of the ASAWEC was fabricated and a series of simulations and experiments was performed to train the supervisor controller and validate the effectiveness of the proposed control approach with regular waves. The results indicated that the system could reach the optimal angle within 2s and subsequently, the output energy could be maximized. Compared to the performance of a system with a vertically fixed slope angle, an increase of 5% in the overall efficiency was achieved. In addition, simulations of the controlled system were performed with irregular waves to confirm the applicability of the proposed approach in practice.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This paper proposes a novel energy maximization algorithm of a sliding-buoy wave energy converter (SBWEC). </LI> <LI> An efficiency optimization mechanism is designed and integrated into the SBWEC. </LI> <LI> The control logic is based on a learning vector quantitative neural network for classifying the wave information. </LI> <LI> The effectiveness of the proposed approach is verified through both simulations and experiments. </LI> </UL> </P>

Therapeutic Possibility of Human Fetal Cartilage- Derived Progenitor Cells in Rat Arthritis Model

이수정,오현주,Minh-Dung Truong,이기범,김지영,김영직,박소라,민병현 한국조직공학과 재생의학회 2015 조직공학과 재생의학 Vol.12 No.4

Fetal cartilage-derived progenitor cells (FCPCs) are a novel cell source for tissue engineering and cell therapy. Previously, cells from various fetal tissues were shown to have immune-modulatory activity just like mesenchymal stem cells. In this study, we investigated the cytotoxicity and therapeutic possibility of FCPCs as a potential cell therapy for arthritis in vivo. To evaluate the acute toxicity and safety, FCPCs were labeled with PKH-26 and subjected to intra-articular injection in rats. When examined at 1 and 2 weeks, the PKH-26 labeled FCPCs were observed only in the synovial membrane but not in other organs. There were no changes either in the white blood cells, red blood cells, and platelets in the hematological analysis and in the weight of the internal organs at 1 week. Therapeutic effect of FCPCs was examined on the complete Freund’s adjuvant (CFA)-induced knee arthritis in rats in comparison with triamcinolone, a representative anti-arthritis drug. When inflammation-related edema of the arthritic knee joint was measured by the knee circumference, it increased significantly from the beginning and maintained until the end of measurement in the CFA group, which decreased back rapidly from 1 day in the triamcinolone group and slowly after 7 days in the FCPCs group. In the histological analysis, both triamcinolone and FCPCs decreased the infiltration of neutrophils and lymphocytes into the arthritic synovial membrane gradually at 3 and 7 days. These results suggest that FCPCs shows low toxicity or immune rejection when injected in the synovial cavity and have a therapeutic potential on the synovial arthritis in the rat model.

Corneal Repair with Adhesive Cell Sheets of Fetal Cartilage-Derived Stem Cells

박인수,Kim Byeong Kook,Truong Minh-Dung,Yang Hong Seok,박상혁,Park Hyo Soon,최병현,Won Bae Hie,민병현 한국조직공학과 재생의학회 2021 조직공학과 재생의학 Vol.18 No.1

Background: Corneal scarring or disease may lead to severe corneal opacification and consequently, severe loss of vision due to the complete loss of corneal epithelial cells. We studied the use of epithelial cell sheets differentiated from fetal cartilage-derived stem cells (FCSC) to resurface damaged cornea. Methods: The FCSC were isolated from the femoral head of immature cartilage tissue. The ability of the FCSCs to differentiate into corneal epithelial cells was evaluated using differentiation media at 2 days and 7 days post-seeding. A sheet fabricated of FCSCs was also used for the differentiation assay. The results of the in vitro studies were evaluated by immunocytochemistry and Western blots for corneal epithelial cell markers (CK3/12 and Pax6) and limbal epithelial stem cell markers (ABCG2 and p63). To test the material in vivo, an FCSC-sheet was applied as a treatment in a chemically burned rabbit model. The healing ability was observed histologically one week after treatment. Results: The in vitro experiments showed morphological changes in the FCSCs at two and seven days of culture. The differentiated cells from the FCSCs or the FCSC-sheet expressed corneal epithelial cells markers. FCSC were create cell sheet that successfully differentiated into corneal epithelial cells and had sufficient adhesion so that it could be fused to host tissue after suture to the ocular surface with silk suture. The implanted cell sheet maintained its transparency and the cells were alive a week after implantation. Conclusion: These results suggest that carrier-free sheets fabricated of FCSCs have the potential to repair damaged corneal surfaces. Background: Corneal scarring or disease may lead to severe corneal opacification and consequently, severe loss of vision due to the complete loss of corneal epithelial cells. We studied the use of epithelial cell sheets differentiated from fetal cartilage-derived stem cells (FCSC) to resurface damaged cornea. Methods: The FCSC were isolated from the femoral head of immature cartilage tissue. The ability of the FCSCs to differentiate into corneal epithelial cells was evaluated using differentiation media at 2 days and 7 days post-seeding. A sheet fabricated of FCSCs was also used for the differentiation assay. The results of the in vitro studies were evaluated by immunocytochemistry and Western blots for corneal epithelial cell markers (CK3/12 and Pax6) and limbal epithelial stem cell markers (ABCG2 and p63). To test the material in vivo, an FCSC-sheet was applied as a treatment in a chemically burned rabbit model. The healing ability was observed histologically one week after treatment. Results: The in vitro experiments showed morphological changes in the FCSCs at two and seven days of culture. The differentiated cells from the FCSCs or the FCSC-sheet expressed corneal epithelial cells markers. FCSC were create cell sheet that successfully differentiated into corneal epithelial cells and had sufficient adhesion so that it could be fused to host tissue after suture to the ocular surface with silk suture. The implanted cell sheet maintained its transparency and the cells were alive a week after implantation. Conclusion: These results suggest that carrier-free sheets fabricated of FCSCs have the potential to repair damaged corneal surfaces.

Effects of non-vertical linear motions of a hemispherical-float wave energy converter

Do, Hoang-Thinh,Dinh, Quang-Truong,Nguyen, Minh-Tri,Phan, Cong-Binh,Dang, Tri-Dung,Lee, Seyoung,Park, Hyung-Gyu,Ahn, Kyoung-Kwan Elsevier 2015 Ocean engineering Vol.109 No.-

<P><B>Abstract</B></P> <P>The hydraulic power-take-off mechanism (HPTO) is one of the most popular methods in wave energy converter (WECs). However, the conventional HPTO with only one direction motion has some drawbacks which limit its power capture capability. This paper proposes an <I>adjustable slope angle wave energy converter</I> (ASAWEC) and investigates the effect of slope angle on the performance of the proposed wave energy converter to find the optimal slope angle with the purpose to increase the power capture capability as well as energy efficiency. A mathematical model of components from a floating buoy to a hydraulic motor was modeled. A small scale WEC test rig was fabricated to verify the power capture capability and efficiency of the proposed system throughout experiments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This paper proposed an adjustable moving angle wave energy converter (AMAWEC). </LI> <LI> Mathematical model of AMAWEC was presented and simulated. </LI> <LI> An AMAWEC test rig were fabricated to do the experiment in variety of wave conditions and moving angle in the water tank. </LI> <LI> The effect of moving angle on the performance of a wave energy converter was investigated to find the optimal moving angle in each wave condition. </LI> <LI> Finally, the effectiveness of AMAWEC has been verified by experimental results. </LI> </UL> </P>

Modeling and Energy Management Strategy in Energetic Macroscopic Representation for a Fuel Cell Hybrid Electric Vehicle

TOXUAN DINH,Le Khac Thuy,Nguyen Thanh Tien,Tri Dung Dang,Cong Minh Ho,Hoai Vu Anh Truong,Hoang Vu Dao,Tri Cuong Do,안경관 사단법인 유공압건설기계학회 2019 드라이브·컨트롤 Vol.16 No.2

Fuel cell hybrid electric vehicle is an attractive solution to reduce pollutants, such as noise and carbon dioxide emission. This study presents an approach for energy management and control algorithm based on energetic macroscopic representation for a fuel cell hybrid electric vehicle that is powered by proton exchange membrane fuel cell, battery and supercapacitor. First, the detailed model of the fuel cell hybrid electric vehicle, including fuel cell, battery, supercapacitor, DC-DC converters and powertrain system, are built on the energetic macroscopic representation. Next, the power management strategy was applied to manage the energy among the three power sources. Moreover, the control scheme that was based on back-stepping sliding mode control and inversed-model control techniques were deduced. Simulation tests that used a worldwide harmonized light vehicle test procedure standard driving cycle showed the effectiveness of the proposed control method.

Gene Transfection of Human Turbinate Mesenchymal Stromal Cells Derived from Human Inferior Turbinate Tissues

Kwon, Jin Seon,Park, Seung Hun,Baek, Ji Hye,Dung, Truong Minh,Kim, Sung Won,Min, Byoung Hyun,Kim, Jae Ho,Kim, Moon Suk Hindawi Publishing Corporation 2016 Stem cells international Vol.2016 No.-

<P>Human turbinate mesenchymal stromal cells (hTMSCs) are novel stem cells derived from nasal inferior turbinate tissues. They are easy to isolate from the donated tissue after turbinectomy or conchotomy. In this study, we applied hTMSCs to a nonviral gene delivery system using polyethyleneimine (PEI) as a gene carrier; furthermore, the cytotoxicity and transfection efficiency of hTMSCs were evaluated to confirm their potential as resources in gene therapy. DNA-PEI nanoparticles (NPs) were generated by adding the PEI solution to DNA and were characterized by a gel electrophoresis and by measuring particle size and surface charge of NPs. The hTMSCs were treated with DNA-PEI NPs for 4 h, and toxicity of NPs to hTMSCs and gene transfection efficiency were monitored using MTT assay, fluorescence images, and flow cytometry after 24 h and 48 h. At a high negative-to-positive charge ratio, DNA-PEI NPs treatment led to cytotoxicity of hTMSCs, but the transfection efficiency of DNA was increased due to the electrostatic effect between the NPs and the membranes of hTMSCs. Importantly, the results of this research verified that PEI could deliver DNA into hTMSCs with high efficiency, suggesting that hTMSCs could be considered as untapped resources for applications in gene therapy.</P>