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Um, Suk-Kee;Lee, Kwan-Soo;Jung, Hye-Mi
- Proceedings of the KSME Conference
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- 2007.05b
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- pp.2250-2254
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- 2007
Comprehensive analytical models focusing on the anode water loss, the cathode flooding, water equilibrium, and water management strategy are developed for polymer electrolyte fuel cells. Analytical solutions presented in this study are compared with two-dimensional computational results and shows a good agreement in predicting those critical characteristics of water. General features of water concentration profile as a function of membrane thickness and current density are presented to illustrate the net effect of the back-diffusion of water from the cathode to anode and the water production by the cathode catalytic reaction on water transport over a fuel cell domain. As one of practical applications, the required humidity level of feed streams for full saturation at the channel outlets are investigated as a function of the physical operating condition. These analytical models can provide good understanding on the characteristic water
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조소훈;박찬헌;이동근
- Proceedings of the Computational Structural Engineering Institute Conference
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- 2004.04a
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- pp.293-300
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- 2004
As the structure is taller and its member is larger, the effect of the deformation of Panel zone on the displacement of structure becomes larger. The analysis using the centerline dimensions in the steel moment frame structure can not consider the accurate effect of panel ton And the finite element analysis using infinitesimal solid and shell element is impractical for the total tall building structure. Therefore, this paper proposes the analytical model using linear element in order to be able to evaluate the reasonable deformation of panel zone. the proposed analytical model makes the analysis of the building structure simple and ease because it uses the only linear elements. In addition it can easily incorporate the various parameters affecting the deformation of panel zone. In order to prove the validith of the prosed analytical model, the analysis result using the proposed analytical model is compared with the result using finite element analysis with shell element
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Kwak Hyo-Gyoung;Ha Soo-Jun
- Proceedings of the Computational Structural Engineering Institute Conference
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- 2005.04a
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- pp.448-455
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- 2005
In this paper, an analytical model for estimation of the time at which the concrete surface begins to dry is introduced to predict whether or not plastic shrinkage cracks occur. First of all, the validity of a consolidation model for bleeding of cement paste proposed by Tan et al. is verified by comparing the analytical results with the experimental results, and used to evaluate the rate and amount of bleed water of concrete. Also an analytical model for evaporation of bleed water which considers the effect of the temperature variation of concrete surface due to hydration heat on the evaporation rate is proposed, and the experimental and analytical results are then compared to verify the validity of the introduced model. In advance, the time at which the concrete surface begins to dry is estimated using above two analytical models, and compared with the experimental results about the time at which plastic shrinkage cracks occur. From the comparison, it is verified that the proposed model can predict the occurrence of plastic shrinkage cracking with comparative precision.
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