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RISS 인기검색어
- 검색키워드
- 저자 : Yujia Jiang (검색결과 3 건)
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Spoof Fingerprint Detection based on Co-occurrence Matrix
Yujia Jiang,Xin Liu 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.8
Fingerprint-based recognition systems have been widely deployed in numerous civilian and government applications. However, the fingerprint recognition systems can be deceived by commonly used sensors with the artificially fake fingerprint made using materials like gelatin or silicon. In this paper, spoof fingerprint detection is considered as a two-class classification problem and co-occurrence matrix is constructed from image gradients to extract features. In feature extraction process, the quantization operation is firstly applied with the fingerprint images. Secondly, the horizontal and vertical differences at each pixel are calculated. Thirdly, the differences of large absolute values are truncated into a reduced range. Finally, the co-occurrence matrix is constructed from the truncated differences, and the elements of the co-occurrence matrix are directly used as features. The features are separately utilized to train support vector machine classifiers on two databases. The experimental results have demonstrated that the proposed method outperform the state-of-the-arts.
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Batch Auditing for Multi-client Dynamic Data in Multi-cloud Storage
Xin Liu,Yujia Jiang 보안공학연구지원센터 2014 International Journal of Security and Its Applicat Vol.8 No.6
Cloud storage introduces many challenges due to the security and integrity threats toward user’s outsourced data. Many auditing protocols have been proposed, but the majority of them could only serve in single cloud environment. This paper proposes an efficient auditing protocol, which supports batch auditing for multiple data files in multi-cloud environment. By utilizing the bilinear map, the proposed protocol achieves full stateless and transparent verification. By constructing a Merkle Hash Tree, the proposed protocol can resist the replace attack and support dynamic operation of data. In addition, our protocol protects the position information of the data blocks by generating fake data blocks to confuse the organizer. The performance analysis demonstrates the efficiency of the protocol.
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Investigation of fl ow regime in debris bed formation behavior with nonspherical particles
Songbai Cheng,Pengfeng Gong,Shixian Wang,Jinjiang Cui,Yujia Qian,Ting Zhang,Guangyu Jiang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.1
It is important to clarify the characteristics of flow regimes underlying the debris bed formation behaviorthat might be encountered in core disruptive accidents of sodium-cooled fast reactors. Although in ourprevious publications, by applying dimensional analysis technique, an empirical model, with itsreasonability confirmed over a variety of parametric conditions, has been successfully developed topredict the regime transition and final bed geometry formed, so far this model is restricted to predictionsof debris mixtures composed of spherical particles. Focusing on this aspect, in this study a new series ofexperiments using nonspherical particles have been conducted. Based on the knowledge and data obtained,an extension scheme is suggested with the purpose of extending the base model to cover theparticle-shape influence. Through detailed analyses and given our current range of experimental conditions,it is found that, by coupling the base model with this scheme, respectable agreement betweenexperiments and model predictions for the regime transition can be achieved for both spherical andnonspherical particles. Knowledge and evidence from our work might be utilized for the futureimprovement of design of an in-vessel core catcher as well as the development and verification of sodium-cooled fast reactor severe accident analysis codes in China.
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