Crystalline GaN films can be grown even on amorphous substrates with the use of graphene buffer layers by pulsed sputtering deposition (PSD). The graphene buffer layers allowed us to grow highly c-axis-oriented GaN films at low substrate temperatures. Full-color GaN-based LEDs can be fabricated on the GaN/graphene structures and they are operated successfully. This indicates that the present technique is promising for future large-area light-emitting displays on amorphous substrates.

A novel compact multi-input multi-output (MIMO) antenna system with split-ring resonator (SRR), a popular metamaterial structure, is presented. The MIMO antenna system consists of SRRs as radiator elements arranged close to each other on a printed circuit board. We evaluate the antenna characteristics with a single and two SRR elements arranged within various sizes of area. We also analyze MIMO channel capacities of SRR elements by using radiation patterns. The obtained results confirm that the proposed MIMO antenna system can achieve the same channel capacity as a conventional MIMO antenna system but with a 30% smaller footprint area and is very suitable for compact wireless equipment in next-generation wireless systems.

In this paper, the performance of a vehicle information sharing (VIS) system for an intersection collision warning system (ICWS) is analyzed. The on-board unit (OBU) of the ICWS sharing obstacle detection sensor information (ICWS-ODSI) is mounted on a vehicle, and it obtains information about the surrounding vehicles, such as their position and velocity, by its in-vehicle obstacle detection sensors. These information are shared with other vehicles via an intervehicle communication network. In this analysis, a T-junction is assumed as the road environment for the theoretical analysis of the VIS performance in terms of the mean of entire vehicle information acquiring probability (MEVIAP). The MEVIAP on OBU penetration rate indicated that the ICWS-ODSI is superior to the conventional VIS system that only shares its own individual driving information via an intervehicle communication network. Furthermore, the MEVIAP on the sensing range of the ICWS-ODSI is analyzed, and it was found that the ISO15623 sensor used for the forward vehicle collision warning system becomes a candidate for the in-vehicle detection sensor of ICWS-ODSI.

Due to heavy rendering load and unstable frame rate when rendering large terrain, this paper proposes a geometry clipmaps based algorithm. Triangle meshes are generated by few tessellation control points in GPU tessellation shader. ‘Cracks’ caused by different resolution between adjacent levels are eliminated by modifying outer tessellation level factor of shared edges between levels. Experimental results show the algorithm is able to improve rendering efficiency and frame rate stability in terrain navigation.

Interference alignment (IA) is a promising technology for eliminating interferences while it still achieves the optimal capacity scaling. However, in practical systems, the IA feasibility limit and the heavy signaling overhead obstructs employing IA to large-scale networks. In order to jointly consider these issues, we propose the feedback overhead-aware IA clustering algorithm which comprises two parts: adaptive feedback resource assignment and dynamic IA clustering. Numerical results show that the proposed algorithm offers significant performance gains in comparison with conventional approaches.

In recent years, the reduced cost and increased capacity of memory have resulted in a growing number of buffers in switches and routers. Consequently, today's networks suffer from bufferbloat, a term that refers to excess frame buffering resulting in high latency, high jitter, and low throughput. Although ring aggregation is an efficient topology for forwarding traffic from multiple, widely deployed user nodes to a core network, a fairness scheme is needed to achieve throughput fairness and avoid bufferbloat, because frames are forwarded along ring nodes. N Rate N+1 Color Marking (NRN+1CM) was proposed to achieve per-flow fairness in ring aggregation networks. The key idea of NRN+1CM is to assign a color that indicates the dropping priority of a frame according to the flow-input rate. When congestion occurs, frames are selectively discarded based on their color and the frame-dropping threshold. Through the notification process for the frame-dropping threshold, frames are discarded at upstream nodes in advance, avoiding the accumulation of a queuing delay. The performance of NRN+1CM was analyzed theoretically and evaluated with computer simulations. However, its ability to avoid bufferbloat has not yet been proven mathematically. This paper uses an M(n)/M/1/K queue model to demonstrate how bufferbloat is avoided with NRN+1CM's frame-dropping threshold-notification process. The M(n)/M/1/K queue is an M/M/1/K queuing system with balking. The state probabilities and average queue size of each ring node were calculated with the model, proving that the average queue size is suppressed in several frames, but not in the most congested queue. Computer simulation results confirm the validity of the queue model. Consequently, it was logically deducted from the proposed M(n)/M/1/K model that bufferbloat is successfully avoided with NRN+1CM independent of the network conditions including the number of nodes, buffer sizes, and the number and types of flows.

For the future medical diagnostics, high-sensitive, rapid, and cost effective biosensors to detect the biomarkers have been desired. In this study, the polymer-based two-dimensional photonic crystal (2D-PC) was fabricated using nanoimprint lithography (NIL) for biosensing application. In addition, for biosensing application, label-free detection of fibrinogen which is a biomarker to diagnose the chronic obstructive pulmonary disease (COPD) could be achieved using antigen-antibody reaction high-sensitively (detection limit: pg/ml order) and rapidly. Using this polymer-based 2D-PC, optical biosensor can be developed cost effectively. Furthermore, by using polymer as a base material for fabrication of 2D-PC, label-free detection of antigen-antibody reaction can be performed in visible region.

We deal with the scattering of a plane wave by the end-face of an ordered waveguide system composed of identical cores of equal space by the perturbation method and derive analytically the diffraction amplitude. It is shown that the results are in relatively good agreement with those obtained by the numerical method.

In this paper, we provided a new variant of Weil pairing on a family of genus 2 curves with the efficiently computable automorphism. Our pairing can be considered as a generalization of the omega pairing given by Zhao et al. We also report the algebraic cost estimation of our pairing. We then show that our pairing is more efficient than the variant of Tate pairing with the automorphism given by Fan et al. Furthermore, we show that our pairing is slightly better than the twisted Ate pairing on Kawazoe-Takahashi curve at the 192-bit security level.

We introduce two cheater identifiable secret sharing (CISS) schemes with efficient reconstruction, tolerating t

IDMs are getting more effective and secure with biometric recognition and more privacy-preserving with advanced cryptosystems. In order to meet privacy and security needs of an IDM, the cryptographic background should rely on reliable random number generation. In this study, a Biometric Random Number Generator (BRNG) is proposed which plays a crucial role in a typical cryptosystem. The proposed novel approach extracts the high-frequency information in biometric signal which is associated with uncertainty existing in nature of biometrics. This bio-uncertainty, utilized as an entropy source, may be caused by sensory noise, environmental changes, position of the biometric trait, accessories worn, etc. The filtered nondeterministic information is then utilized by a postprocessing technique to obtain a random number set fulfilling the NIST 800-22 statistical randomness criteria. The proposed technique presents random number sequences without need of an additional hardware.

Audio hashing has been successfully employed for protection, management, and indexing of digital music archives. For a reliable audio hashing system, improving hash matching accuracy is crucial. In this paper, we try to improve a binary audio hash matching performance by utilizing auxiliary information, resilience mask, which is obtained while constructing hash DB. The resilience mask contains reliability information of each hash bit. We propose a new type of resilience mask by considering spectrum scaling and additive noise distortions. Experimental results show that the proposed resilience mask is effective in improving hash matching performance.

We previously proposed an unsupervised model using the inclusion-exclusion principle to compute sentence information content. Though it can achieve desirable experimental results in sentence semantic similarity, the computational complexity is more than O(2n). In this paper, we propose an efficient method to calculate sentence information content, which employs the thinking of the difference set in hierarchical network. Impressively, experimental results show that the computational complexity decreases to O(n). We prove the algorithm in the form of theorems. Performance analysis and experiments are also provided.

The sparse representation models have been widely applied in image super-resolution. The certain optimization problem is supposed and can be solved by the iterative shrinkage algorithm. During iteration, the update of dictionaries and similar patches is necessary to obtain prior knowledge to better solve such ill-conditioned problem as image super-resolution. However, both the processes of iteration and update often spend a lot of time, which will be a bottleneck in practice. To solve it, in this paper, we present the concept of image quality difference based on generalized Gaussian distribution feature which has the same trend with the variation of Peak Signal to Noise Ratio (PSNR), and we update dictionaries or similar patches from the termination strategy according to the adaptive threshold of the image quality difference. Based on this point, we present two sparse representation algorithms for image super-resolution, one achieves the further improvement in image quality and the other decreases running time on the basis of image quality assurance. Experimental results also show that our quantitative results on several test datasets are in line with exceptions.

This paper proposes a recommendation-based bandwidth calendaring system for packet transport networks. The system provides a user-portal interface with which users can directly reserve packet transport resources. In this regard, the system recommends multi-grade (e.g., multi-price) reservation plans. By adjusting grades of plans in accordance with network resource utilization, this system provides not only reservation flexibility for users but also efficient utilization of network resources. For recommending multi-grade plans, pre-computation of resource allocation is required for every time slot. Because the number of time slots is huge, we also propose an algorithm for fast computation of resource allocation based on time-slot aggregation. Our evaluation suggests that our algorithm can produce a sub-optimal solution within quasi-real time for a large-scale network. We also show that our recommendation-based system can increase the service-provider-revenue in peaky traffic demand environments.

The online unit clustering problem is one of the most basic clustering problems proposed by Chan and Zarrabi-Zadeh (WAOA2007 and Theory of Computing Systems 45(3), 2009). Several variants of this problem have been extensively studied. In this letter, we propose a new variant of the online unit clustering problem, called the online unit clustering problem with capacity constraints. For this problem, we use competitive analysis to evaluate the performance of an online algorithm. Then, we develop an online algorithm whose competitive ratio is at most 3.178, and show that a lower bound on the competitive ratio of any online algorithm is 2.

Many researchers studied computationally-secure (verifiable) secret sharing schemes which distribute multiple secrets with a bulletin board. However, the security definition is ambiguous in many of the past articles. In this paper, we first review existing schemes based on formal definitions of indistinguishability of secrets, verifiability of consistency, and cheater-detectability. And then, we propose a new secret sharing scheme which is the first scheme with indistinguishability of secrets, verifiability, and cheater-detectability, and allows to share secrets with arbitrary access structures. Further, our scheme is provably secure under well known computational assumptions.

Attacks against computer networks are evolving rapidly. Conventional intrusion detection system based on pattern matching and static signatures have a significant limitation since the signature database should be updated frequently. The unsupervised learning algorithm can overcome this limitation. Ant Clustering Algorithm (ACA) is a popular unsupervised learning algorithm to classify data into different categories. However, ACA needs to be complemented with other algorithms for the classification process. In this paper, we present a fuzzy anomaly detection system that works in two phases. In the first phase, the training phase, we propose ACA to determine clusters. In the second phase, the classification phase, we exploit a fuzzy approach by the combination of two distance-based methods to detect anomalies in new monitored data. We validate our hybrid approach using the KDD Cup'99 dataset. The results indicate that, compared to several traditional and new techniques, the proposed hybrid approach achieves higher detection rate and lower false positive rate.

The self-organizing nature of ad hoc networks is a good aspect in that terminals are not dependent on any infrastructure, that is, networks can be formed with decentralized and autonomous manner according to communication demand. However, this characteristic might affect the performance in terms of stability, reliability and so forth. Moreover, ad hoc networks face a scalability problem, which arise when the number of terminals in a network increases or a physical network domain expands, due to the network capacity limitation caused by the decentralized and the autonomous manner. Regarding this problem, some hierarchical and cluster-based routings have been proposed to effectively manage the networks. In this paper, we apply the concept of hierarchical routing and clustering to opportunistic routing, which can forward packets without using any pre-established path to achieve a path diversity gain with greater reachability. The simulation results show that the proposed method can achieve 11% higher reliability with a reasonable end-to-end delay in dense environments and 30% higher in large-scale networks.

Non-volatile memories are paid attention to as a promising alternative to memory design. Data stored in them still may be destructed due to crosstalk and radiation. We can restore the data by using error-correcting codes which require extra bits to correct bit errors. Further, non-volatile memories consume ten to hundred times more energy than normal memories in bit-writing. When we configure them using error-correcting codes, it is quite necessary to reduce writing bits. In this paper, we propose a method to generate a bit-write-reducing code with error-correcting ability. We first pick up an error-correcting code which can correct t-bit errors. We cluster its codeswords and generate a cluster graph satisfying the S-bit flip conditions. We assign a data to be written to each cluster. In other words, we generate one-to-many mapping from each data to the codewords in the cluster. We prove that, if the cluster graph is a complete graph, every data in a memory cell can be re-written into another data by flipping at most S bits keeping error-correcting ability to t bits. We further propose an efficient method to cluster error-correcting codewords. Experimental results show that the bit-write-reducing and error-correcting codes generated by our proposed method efficiently reduce energy consumption. This paper proposes the world-first theoretically near-optimal bit-write-reducing code with error-correcting ability based on the efficient coding theories.