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Hung, Nguyen Ba,Sung, Jaewon,Lim, Ocktaeck Elsevier 2018 APPLIED ENERGY Vol.221 No.-
<P><B>Abstract</B></P> <P>The objective of this study is to investigate the dynamic characteristics and optimize the required power of an electric bicycle equipped with a semi-automatic transmission. In this simulation, we analyze the dynamic characteristics and operating characteristics of an electric bicycle at each gear ratio based on the effects of input parameters such as gear-speed, frontal area, and slope grade by using Matlab-Simulink. Through this simulation, an analysis is conducted to maximize the power generation of the electric bicycle. The simulation results show that the required power can be optimized by changing the key parameters mentioned above. In addition, a model-based control study is conducted to control the bicycle speed under the effects of gear-speed and slope grade. We also conduct an experiment on a real road and analyze the dynamics and required power of the electric bicycle. The experimental results agree well with the simulation results at each transmission ratio. This combination of simulations and experiments provides a useful method to estimate the power requirements for the motor of an electric bicycle.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Mathematical models are established to describe the operation of electric bicycle. </LI> <LI> The bicycle operating performance is studied under the effects of input parameters. </LI> <LI> A model-based control study is conducted under the effects of gear-speed and slope. </LI> <LI> An experimental study of the electric bicycle is conducted. </LI> <LI> Motor power is estimated based on a combination between simulation and experiment. </LI> </UL> </P>
Nguyen Ba Hung,Yong Il Oh,Ock Taeck Lim 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
A numerical analysis was investigated on the two stroke free piston linear engine. The analyses were carried out based on the combination of three model including dynamic, linear alternator and thermodynamic model. The reciprocating mass, air gap length, spring hardness, and dimension of cylinder were used as investigation parameters in the paper. The simulation results showed that by changing the reciprocating mass from 1 kg to 2.5 kg, the motion characteristic and performance of engine are reduced. Contrary to effects of reciprocating mass, the performance of engine was increased by increasing air gap length from 1.5mm to 3mm. In other hand, when increasing spring hardness from 0.5 N/mm to 14.7 N/mm, the operation characteristic was improved. Beside, the changing for some parameters related to the dimension of cylinder also had certain effects to the operation of the engine.
Nguyen Ba Hung,Ocktaeck Lim 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.2
A model-based study is conducted to develop a high-performance solenoid gas injector applied for compressed natural gas (CNG) fueled engines. Operation of the solenoid gas injector is described through mathematical models, including mechanical and electrical models. The solenoid of the gas injector is modeled in Maxwell software to simulate its electromagnetic force in static mode, which is based on specifications of a real solenoid gas injector. The electromagnetic force along with flux obtained by the solenoid model in Maxwell is then imported into AMESim software to simulate the operating characteristics of the solenoid gas injector in transient mode, such as motion characteristics of the plunger, response time, and injection quantity. The electromagnetic force and operating characteristics of the solenoid gas injector are investigated under the effects of structural parameters, including core and sleeve shapes. The simulation results show that the electromagnetic force and open response time of the solenoid gas injector are significantly improved by changing the core and sleeve shapes.
Ba Hung, Nguyen,Lim, Ocktaeck Elsevier 2019 APPLIED ENERGY Vol.247 No.-
<P><B>Abstract</B></P> <P>A study is conducted to examine the motion, dynamic and electric consumption characteristics of an electric assisted bicycle based on the effects of certain operating conditions and structural parameters. Simulation models for operation of the electric assisted bicycle, including dynamic models of the electric assisted bicycle and battery models, are established. These simulation models are solved by MATLAB-Simulink to provide the operating characteristics of the electric assisted bicycle. Based on the established mathematical models, the motion, dynamic and electric consumption of the electric assisted bicycle are analyzed and optimized under the effects of slope, bicycle mass, wheel radius, crank length, and sprocket transmission ratio. The simulation results show that the dynamic performance and electric consumption of the electric assisted bicycle are significantly improved by reducing the bicycle mass, wheel radius, and increasing the sprocket transmission ratio. The dynamic performance and electric consumption are optimal when the slope grade, bicycle mass, wheel radius, crank length, and sprocket transmission ratio are 0%, 12 kg, 0.32 m, 0.17 m and 3.43, respectively. A study for using the regenerative energy generated during the downhill movement of the electric assisted bicycle to create electrical power is presented under the effects of rider mass and slope angle. An experimental study is also conducted to examine the motion and electric consumption characteristics of the electric assisted bicycle under real operating conditions. This study shows agreement between simulation and experimental results at the same initial conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The operation of an EAB is described by dynamic models and battery model. </LI> <LI> Effects of input parameters on the electric consumption of the EAB are investigated. </LI> <LI> A study for electric power generation is conducted using a modeling approach. </LI> <LI> An experimental study for motion and electric consumption of the EAB is conducted. </LI> </UL> </P>
( Nguyen Thi Hang ),( Nguyen Thi Bich Thu ),( Le Ba Vinh ),( Nguyen Viet Phong ),( Tran Van On ),( Ki Yong Lee ) 한국미생물생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.7
Metabolites from medicinal plants continue to hold significant value in the exploration and advancement of novel pharmaceuticals. In the search for plants containing compounds with anti-inflammatory effects, we observed that the ethanol (EtOH) extract obtained from the aerial components of Gouania leptostachya DC. var. tonkinensis Pit. exhibited substantial suppression of nitric oxide (NO) in vitro. In a phytochemical study on an EtOH extract of G. leptostachya, 11 compounds were purified, including one unreported compound namely gouanioside A (1). Their chemical structures were unambiguously determined through the use of various spectroscopic techniques, such as 1 and 2D NMR, IR, and HR-ESI-MS, and by producing derivatives via chemical reactions. The EtOH extract, fractions, and a new compound exerted inflammatory effects by altering NO synthesis in murine RAW264.7 macrophage cells stimulated with lipopolysaccharide. The underlying inflammatory mechanism of the new compound 1 was also explored through various in vitro experiments. The results of this study indicate the potential usefulness of new compound 1 from G. leptostachya as a treatment for inflammatory diseases.
The Research about Free Piston Linear Engine fueled with Hydrogen using Numerical Analysis
Nguyen Ba Hung,Yong Il Oh,Jin Bok Kim,Ock Taeck Lim 한국자동차공학회 2011 한국자동차공학회 지부 학술대회 논문집 Vol.2011 No.10-2
This paper presents a research about free piston linear engine (FPLE) fueled with hydrogen, in which, numerical model was built to simulate the different processes that take place during the full stroke of engine. Dynamic model and thermodynamic model were used to predict piston speed, piston acceleration, in-cylinder pressure, indicated mean effective pressure (IMEP) and indicated efficiency. The compression ratio and bore were changed to provide information for the prediction. In this paper, the thermodynamic model was calculated based on an idealized Otto cycle, including compression, combustion and expansion. Simulation results show that velocity and acceleration increase when compression ratio and bore increase. Beside, by increasing compression ratio, IMEP and indicated efficiency also increase. On the contrary, by increasing bore, IMEP and indicated efficiency will decrease accordingly.
Simulation of a Free Piston Linear Engine fueled with LPG
Nguyen Ba Hung,Yong Il Oh(오용일),Ock Taeck Lim(임옥택) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
This paper presents a simulation research about free piston linear engine (FPLE) fueled with LPG include 30% propane and 70% butane. Dynamic model, linear alternator model and thermodynamic model are used as the numerical models to predict motion of piston, in-cylinder pressure and generated electric power of FPLE. The spark timing and air gap length are changed to provide information for the prediction. The result of this research is divided by two parts include motoring mode and firing mode. The result at motoring mode showed that there is validation between simulation and experiment for volume and pressure in cylinder. In regard to firing mode, by increasing spark timing, the velocity of piston, peak pressure and electric power increase respectively. Beside, by increasing air gap length, the velocity of piston change insignificantly, however both the peak pressure and electric power decrease respectively.