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Keyword K-Nearest Neighbor Query of Road Network under Wireless Broadcast Environment
Chen Wen 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.4
As a new branch of location-based query, space keyword query has gained extensive attention from researchers and become a new hotspot of database filed. Able to comprehensively consider the distance between query object and query point as well as similarity degree of keywords, such query can better satisfy specific requirements of location-based services. In this paper, a space keyword index structure is designed, so as to effectively organize keyword information, location information and index information of objects on various sides in road network. Besides, keyword k-nearest neighbor query of road network under wireless broadcast environment is proposed. Finally, performance of the proposed index structure and algorithm is verified through simulation experiment.
Chen Wen,Jing Sicheng,Wang Yu,Pan Jinghua,Li Wei,Bian Baoan,Liao Bin 한국물리학회 2022 Current Applied Physics Vol.43 No.-
Two-dimensional materials have attracted great attention because of their ultra-thin atomic layer thickness and high carrier mobility. In this work, we investigated the electronic transport of in-plane (IP) heterojunction based on Cu/Blue Phosphorus (BlueP), and the results suggest the metallization at the IP Cu/BlueP contact interface and a small Schottky barrier. Then, we investigated the performance of 5.1 nm IP BlueP Schottky barrier field-effect transistors (SBFET) with different dielectrics (SiO2, Al2O3, Y2O3, and La2O3) using quantum transport simulations. The results show that IP BlueP SBFETs with four dielectrics satisfy the off-state requirement of the International Technology Roadmap for Semiconductors (ITRS) for the high-performance (HP) device. However, the on-state current of only IP BlueP SBFET with La2O3 satisfies the requirements of ITRS. This will provide a reference for designing BlueP SBFETs.
Road Network-based Location Privacy Protection
Chen Wen 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.12
The traditional location privacy protection means mainly employs reliable central server framework, and it mainly applies the anonymous region meeting the k-anonymity at the anonymous server to replace the real location of users. However, the disadvantages of the central server, such as being attacked easily, high communication cost, etc. are disclosed accordingly. In addition, the anonymous method of most locations is oriented for the European style, and it is not applicable to the road network. In order to solve the above problem, virtual user group-based centerless server framework is proposed for solving the location privacy protection in road network. This algorithm mainly forms the virtual user group with several virtual users in several road segments of the road network, and replaces the real position of the user with a certain point in the section, so as to realize the k-anonymity of user position with the increment nearest neighbor query. Since the algorithm adopts the accurate increment nearest neighbor query method, it guarantees the service quality. The experiment proves that the algorithm can reduce the communication cost effectively and improve the application safety.
An Effective K-Nearest Neighbor Track Retrieval Algorithm
Chen Wen 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.3
Due to the mass track data accumulated day by day, new challenges are raised for traditional information retrieval. This paper studies the issue of k-nearest neighbor track retrieval facing moving object, and converts this issue into aggregate Top-k query issue of information retrieval field. A parallel TA algorithm in random access database is proposed, and it has effectively solved the issue of k-nearest neighbor track retrieval. Performance of this algorithm is verified through a large number of experiments.
Privacy-Preserving for Check-In Services in MSNS Based on Association Graph
Chen Wen 보안공학연구지원센터 2014 International Journal of u- and e- Service, Scienc Vol.7 No.6
Check-in service as one of the most popular services in mobile social network services (MSNS), has serious personal privacy leakage threats. In this paper, check-in sequences of pseudonym users were buffered , and association graph for buffered check-in sequences was built, which can achieve a privacy guarantee of k-anonymity. The method guarantee the number of lost check-in locations is minimized while satisfying users' privacy requirements, it is also reduces the cost of finding trajectory k-anonymity set. At last, the results of a set of comparative experiments with (k, δ) - anonymity on real world datasets show the method's accuracy and effectiveness.
Chen, Wen,Han, Dong-Keun,Ahn, Kwang-Duk The Polymer Society of Korea 2002 Macromolecular Research Vol.10 No.2
A molecularly imprinted polymer (MIP) having both amidine and imidazole functional groups in the active site has been prepared using p-nitrophenyl phosphate as a transition state analogue (TSA). The imprinted polymer MIP with amidine and imidazole found to have the highest hydrolysis activity compared with other MIPs with either amidine or imidazole groups only. It is postulated a cooperative effect between amidine and imidazole in the hydrolysis of p-nitrophenyl methyl carbonate (NPMC) as a substrate when both groups were arranged in proximity by molecular imprinting. The rate enhancement of the hydrolysis by MIP was 60 folds over the uncatalyzed solution reaction and two folds compared with the control non-imprinted polymer CPI having both functional groups. The enzyme-mimetic catalytic hydrolysis of p-nitrophenyl acetate by MIP was evaluated in buffer at pH 7.0 with $K_{m}$ of 1.06 mM and $k_{cat}$ of 0.137 $h^{-1}$ . . .
Privacy-Preserving for Check-In Services in MSNS Based on Ant Colony Algorithm
Chen Wen 보안공학연구지원센터 2015 International Journal of Grid and Distributed Comp Vol.8 No.3
The sign-in service of Mobile Social Networking Services (MSNS) has a serious issue of privacy disclosure. As to solving this issue, there is a method proposed to protect privacy. This method is to conduct binary coding for sign-in sequence and then construct ant path diagram. The random search, the positive and negative feedback principle of ant path graph are applied to mine frequent item sets. The longest common subsequence is achieved from sign-in sequence and corresponding frequent item sets. Finally, k-anonymous sign-in sequence will be obtained. Based on real data, this method is compared with (k, δ) - anonymity which proves the accuracy and efficiency of this method through various aspects.
Continuous Reverse k-Nearest-Neighbor Query in Dynamic Road Network
Chen Wen 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.5
Traditional location-based query measures the distance of all data points in various methods, but it is not applicable for the condition in which the weight of all sections in the road network are altered dynamically. In order to solve the new application problems brought by the real-time traffic status, a dynamic monitoring algorithm is designed in this paper, and it mainly updates the weight changes of road network with temporary network extension tree incrementally. On this basis, a continuous reverse K-nearest-neighbor (RKNN) query method is proposed, and it is proved to be efficient by the experimental results.
K-Aggregate Nearest Neighbor Query Method of Moving Objects in Road Networks
Chen Wen 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.4
K-aggregate nearest neighbor query method of mobile objects in road networks is studied. Moving state model of object is introduced, and road network distance calculation formula is provided. Besides, this paper designs a kANN query algorithm that can find out the previous k target nodes with the smallest aggregate function value among multiple target nodes for various query points when query points and data points are under moving state in road networks. The candidate results are cut short via pruning method. Finally, performance of the algorithm is verified through simulation experiment, and results of the simulation experiment prove that this algorithm has high efficiency and accuracy.
Morphological, Physiological and Biochemical Responses of Gerbera Cultivars to Heat Stress
Chen, Wen,Zhu, Xiaoyun,Han, Weiqing,Wu, Zheng,Lai, Qixian Korean Society of Horticultural Science 2016 원예과학기술지 Vol.34 No.1
Heat stress is an agricultural problem for Gerbera jamesonii, and it often causes poor seedling growth, reduced flower yield and undesirable ornamental characteristics of flowers. However, little is known about the effect of heat stress on the morphological, physiological and biochemical characteristics of gerbera plants. Here, the responses of six cultivars of Gerbera jamesonii to heat stress were investigated. Under a 1-d heat treatment at $45^{\circ}C$, the leaves of gerbera cultivars showed yellowing, wilting, drying and death to varying degrees. The heat treatment also resulted in increased electrical conductivity, decreased soluble protein and chlorophyll contents, and the accumulation of malondialdehyde (MDA) and proline in leaves. Moreover, heat tolerance differed among the six tested gerbera cultivars. Our results demonstrated that among the six gerbera cultivars, 'Meihongheixin' is a heat-resistant cultivar, whereas 'Beijixing' is a heat-sensitive one. 'Shijihong' and 'Linglong' are relatively heat-resistant cultivars, and 'Dadifen' and 'Taiyangfengbao' are relatively heat sensitive.