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- 저자 : Huafeng Gao (검색결과 3 건)
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Reputation and Trust Mathematical Approach for Wireless Sensor Networks
Haiguang Chen,Gangfeng Gu,Huafeng Wu,Chuanshan Gao 보안공학연구지원센터 2007 International Journal of Multimedia and Ubiquitous Vol.2 No.3
In Wireless Sensor Networks (WSNs), these sensor nodes cooperate with each other to form a network without using any infrastructure. WSNs has a wide application. But the security of WSNs is still an important issue. Some existing approaches mainly rely on cryptography to ensure data authentication and integrity. These approaches only address part of the problem of security in WSNs. However, these approaches are not sufficient for the unique characteristics and novel misbehaviors encountered in WSNs. Recently, the use of reputation systems has become an important mechanism in WSNs. In this paper we propose a reputation and trust mathematical framework for WSNs which borrows tools from probability, statistics and mathematics analysis. We have suggested a new term certainty used in trust system and we argued that the positive or negative outcomes for a certain event is not enough information to make a decision in WSNs. We build up a reputation space and trust space in WSNs, and define a transformation from reputation space to trust space. Finally, we discuss some important properties of them and provide a basement in the trust and reputation for future research in WSNs. And we point out some open problems in reputation and trust system in WSNs.
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Preparation and enzymatic activity of Fe3O4-IDA-Ni/NAD kinase magnetic catalyst
Changxia Liu,Yadi Yang,Huafeng Gao,Xiaoshuang Bai,Zheng-Jun Li 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.3
The use of oxidoreductases as biocatalysts for industrial production of valuable compounds has a strong demand for NADP. Herein, we prepared superparamagnetic NAD kinase catalyst to synthesize NADP in vitro. First, Fe3O4 particles were synthesized through a solvothermal method, followed by the chemical modification with epichlorohydrin, iminodiacetic acid, and Ni2+ to yield functional Fe3O4 sub-microspheres. Subsequently, NAD kinase of Escherichia coli was overexpressed and immobilized on to the surface of magnetic sub-microspheres. The immobilized NAD kinase was used to catalyze the conversion of NAD to NADP in a cell-free system. Under optimal condition, the conversion ratio of NAD reached 91.7% and remained at 86.3% after repeated use for five times. Our study revealed that the novel magnetic NAD kinase catalyst possessed favorable properties for magnetic manipulation and NADP production.
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A New Satisfaction Evaluation Method Based on Fuzzy Clustering
Jingfei Ren,Yonghuan He,Mingming Hu,Maozhu Jin,Huafeng Gao 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.9
In recent years, the world tourism is developing rapidly. The world tourism firstly hit 1 billion in 2012. Along with the tourism booming, complaint cases are growing and tourists' satisfaction degree is dropping. In this case, to ensure the interests of tourists and keep sustainable development of tourism, the tourists' satisfaction should be evaluated and the Scenic should be improved based on the evaluation result. In this paper, a new tourist satisfaction evaluation method is proposed based on fuzzy clustering. Firstly, the large scale evaluation data is divided to parts by the fuzzy clustering method. Then, each center of the parts is chosen to evaluate the tourist satisfaction. The new evaluation method is different from the traditional methods. It can effectively cut the evaluation scale. Finally, the tourist satisfaction of Three Gorges Scenic is studied to interpret the new evaluation method.
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