• Journal of Energy Engineering
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• v.19 no.3
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• pp.188-194
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• 2010

Direct Carbon Fuel Cell(DCFC), unlike gas turbines or engines, is a kind of fuel cell which directly generates electricity by electrochemical reaction from a carbon fuel. The advantages of DCFC are higher efficiency and lower emission in comparison with existing power generation facilities. In this study, the effects of CO and $CO_2$ on theoretical potential are examined using the thermodynamic equilibrium method, and the dependence of product on operating temperature is examined via two dimensional CFD method. As a result, when the reaction of CO production (Boudouard reaction) considered, theoretical potential is higher than that in only $CO_2$ reactions, and its value increases as temperature increases. Two dimensional results of computational fluid dynamics(CFD) confirm that the Boudouard reaction becomes more important to be considered as temperature increases and inert gas affects the equilibrium composition of the Boudouard reaction.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2719-2724
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• 2003

In this paper, we deal with the kinematic and dynamic modeling of hybrid robotic systems that are constructed by combination of parallel and serial modules or series of parallel modules. Previously, open-tree structure has been employed for dynamic modeling of hybrid robotic systems. Though this method is generally used, however, it requires expensive computation as the size of the system increases. Therefore, we propose an efficient dynamic modeling methodology for hybrid robotic systems. Initially, the dynamic model for the proximal module is obtained with respect to the independent joint coordinates. Then, in order to represent the operational dynamics of the proximal module, we model virtual joints attached at the top platform of the proximal module. The dynamic motion of the next module exerts dynamic forces to the virtual joints, which in fact is equivalent to the reaction forces exerted on the platform of the lower module by the dynamics of the upper module. Then, the dynamic forces at the virtual joints are distributed to the independent joints of the proximal module. For multiple modules, this scheme can be constructed as a recursive dynamic formulation, which results in reduction of the complexness of the open-tree structure method for modeling of hybrid robotic systems. Simulation for inverse dynamics is performed to validate the proposed modeling algorithm.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.862-868
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• 2012

Based on the recently derived general expression for the rates of diffusion-controlled reactions, we calculate the rates of dismutation of the superoxide anion radical catalyzed by Cu/Zn superoxide dismutases (SOD). This is the first attempt to calculate the absolute rates of diffusion-controlled enzyme reactions based on the atomiclevel molecular dynamics simulations. All solvent molecules are included explicitly and the effects of the structural flexibility of enzyme, especially those of side chain motions near the active site, are included in the present calculation. In addition, the actual mobility of the substrate molecule is taken into account, which may change as the molecule approaches the active site of enzyme from the bulk solution. The absolute value of the rate constant for the wild type SOD reaction obtained from MD simulation is shown to be in good agreement with the experimental value. The calculated reactivity of a mutant SOD is also in agreement with the experimental result.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.745-752
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• 2007

In this study, the effects of flexible bodies in vehicle suspension components were investigated to enhance the accuracy of multibody dynamic simulation results. Front and rear suspension components were investigated. Subframes, a stabilizer bar, a tie rod, a front lower control arm, a front knuckle, and front struts were selected. Reverse engineering techniques were used to construct a virtual vehicle model. Hard points and inertia data of the components were measured with surface scanning equipment. The mechanical characteristics of bushings and dampers were obtained from experiments. Reaction forces calculated from the multibody dynamics simulations were compared with test results at the ball joint of the lower control arm in both time-history and range-pair counting plots. Simulation results showed that the flexibility of the strut component had considerable influence on the lateral reaction force. Among the suspension components, the flexibility of the sub-frame, steering knuckle and upper strut resulted in better correlations with test results while the other flexible bodies could be neglected.

• Journal of ILASS-Korea
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• v.18 no.4
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• pp.202-208
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• 2013

The present study aims to investigate the flow characteristics with respect to fuel type and equivalence ratio in the flame spray coating process. The flame spray flow is characterized by much complex phenomena including combustion, turbulent flows, and combined heat transfer. The present study numerically simulated the flam spray process and examined the gas dynamics involving combustion, gas temperature and velocity distributions in flame spray process by using commercial computational fluid dynamics (CFD) code of FLUENT (ver. 13.0). In particular, we studied the effect of fuel type and equivalence ratio on thermal and flow characteristics which could substantially affect the coating performance. From the results, it was found that the gas temperature distributions were varied with different fuels because of reaction times were different according to the fuel type. The equivalence ratio also could change the spatial flame distribution and the characteristics of coated layer on the substrate.

• International Journal of Air-Conditioning and Refrigeration
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• v.16 no.3
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• pp.89-99
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• 2008

Indoor ozone has received attention because of its well-documented adverse effects on health. In addition to the inherently harmful effects of ozone, it can also initiate a series of reactions that generate potentially irritating oxidation products, including free radicals, aldehydes, organic acids and secondary organic aerosols (SOA). Especially, ozone reacts actively with terpene. The overarching goal of this work was to better understand ozone and terpene distributions within rooms. Towards this end, the paper has two parts. The first describes the development of a cylindrical test chamber that can be used to obtain the second order rate constant $(k_b)$ for the bi-molecular chemical reaction of ozone and terpene in the air phase. The second consists of model room experiments coupled with Computational Fluid Dynamics (CFD) analysis of the experimental scenarios to obtain ozone and terpene distributions in various turbulent flow fields. The results of CFD predictions were in reasonable agreement with the experimental measurements.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1003-1008
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• 2007

Compliance effect consideration method for real-time multibody vehicle dynamics is proposed using quasi-static analysis. The multibody vehicle model without bush elements is used based on the subsystem synthesis method which provides real-time computation on the multibody vehicle model. Reaction forces are computed in the suspension subsystem. According to deformation from the quasi-static analysis using reaction forces and bush stiffness, suspension hardpoint locations and suspension linkage orientation are changed. To validate the proposed method, quarter car simulations of McPherson strut and multilink suspension subsystems. Full car bump run simulations are also carried out comparing with the ADAMS vehicle model with bush elements. CPU times are also measured to see the real-time capabilities of the proposed method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.5
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• pp.809-818
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• 1997

An efficient non-recursive formulation of dynamic force analysis has been developed for serially connected multibody systems. Although derivation of equations of motion is based on a recursive dynamic formulation with joint relative coordinates, in the proposed formulation, dynamic forces such as joint reaction forces and driving force are computed non-recursively for specified joints. The efficiency of the proposed formulation has been proved by the operational count and the CPU time measure, comparing with that of the conventional recursive Newton-Euler formulation. A simulation of 7-DOF RRC robot arm has been carried out to validate solutions of reaction forces by comparing with those from a commercial dynamic analysis program DADS.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.2
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• pp.162-169
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• 2008

Compliance effect consideration method for real-time multibody vehicle dynamics is proposed using quasi-static analysis. The multibody vehicle model without bush elements is used based on the subsystem synthesis method which provides real-time computation on the multibody vehicle model. Reaction forces are computed in the suspension subsystem. According to deformation from the quasi-static analysis using reaction forces and bush stiffness, suspension hardpoint locations and suspension linkage orientation are changed. To validate the proposed method, quarter car simulations of McPherson strut and multilink suspension subsystems are performed. Full car bump run simulations and fish hook handling test simulations are also carried out comparing with the ADAMS vehicle model with bush elements. CPU times are also measured to see the real-time capabilities of the proposed method.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.185-191
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• 2001

In many papers, the powertrain system generally has been madeled as one-dimensional torque model. One-dimensional powertrain model may calculate the torque correctly but it does not consider the non-rotational degrees-of-freedom of the powertrain components and the interaction of these degrees-of-freedom with the vehicle body frame and suspension. To consider the non-rotational degrees of freedom, the differential is modeled as a three-dimensional rigid body in this paper. A constant velocity joint is newly formulated and a relative constraint is also formulated to model the motion transfer due to gear ratio of the differential. Implementing the proposed powertrain system in the multibody model, more detail dynamic responses can be obtained. Obtained outputs such as reaction torques on the constant velocity joint and reaction forces on the rack can be useful data in the design of a powertrain.