Browsing by Author "Chen, Yu-Chi"

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A modified hydrodynamic model for pool boiling CHF considering the effects of heater size and nucleation site density
(2015-05-01)
Lu, Ming-Chang
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Huang, Chih-Hung
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Huang, Chung-Te
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Chen, Yu-Chi
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機械工程學系
Boiling is commonly used in daily life and is an efficient heat removal method. During pool boiling, the critical heat flux (CHF) establishes the upper limit of efficient heat removal. Although, numerous studies have explored CHF, its exact mechanisms remain ambiguous. The hydrodynamic instability model is the most prominent CHF model, but it fails to explain the evident dependence of CHF on surface properties. The authors proposed modifying the hydrodynamic model to account for how nucleation site density and finite heater size affect the CHF. The experimental CHF values obtained from evaluating various types of surfaces qualitatively agreed with the predictions of the modified hydrodynamic model. This suggests that the CHFs on these surfaces were due to the hydrodynamic limit. (C) 2015 Elsevier Masson SAS. All rights reserved.
Strongly Secure Certificate less Signature: Cryptanalysis and Improvement of Two Schemes
(2015-01-01)
Chen, Yu-Chi
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Tso, Raylin
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Horng, Gowboa
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Fan, Chun-I
;
Hsu, Ruei-Hau
Certificateless cryptography is a well-known system to avoid the key escrow problem of identity-based cryptography. Since it was introduced by Al-Riyami and Paterson in 2003, plenty of schemes and security models had been presented and discussed. Particularly, certificateless signature (CLS) is the most lightened to attract research attention. In the literature works, Hu et al. introduced generic construction and security model that can satisfy non-repudiation. On the other hand, Huang et al. simulated possible attacks and defined more complete security models of CLS for existential unforgeability, and they sorted adversaries into normal, strong, and super adversaries (ordered by their attack powers). In this paper, we consider the security of CLS schemes regarding both of existential unforgeability and non-repudiation. We not only show the weaknesses of two CLS schemes of Fan et al. [5] and Xiong et al. [13], but also point out the loopholes of their security proofs. Hence, we improve the weaknesses and loopholes by proposing a new certificateless short signature with low bandwidth. The proposed scheme is provably secure against the super adversaries and reaches the highest security level.