Asymmetrically designed polycrystalline silicon (poly-Si) thin film transistors (TFT) were fabricated and investigated to suppress kink effect and to improve electrical reliability. Asymmetric dual channel length poly-Si TFT (ADCL) shows the best reduction of kink and leakage currents. Technology computer-aided design simulation proves that ADCL can induce properly high voltage at floating node of the TFT at high drain-source voltage (VDS), which can mitigate the impact ionization and the degradation of the transconductance of the TFT showing high reliability under the hot carrier stress.

With the rising innovative antigens (such as intruders and viruses) through Internet, reliable security mechanisms are required to perceptively detect and put them down. However, defense techniques of the current host system over Internet may not properly analyze Internet antigens, because trends of attacks are unexpectedly shifted. In this paper, we introduce an Antibody Layer that mediates proper security services based on the biological mechanism to rapidly disclose and remove innovative antigens. The proposed Antibody Layer also employs a new topology called antibody cooperation protocol to support real-time security QoS for one host as well as host alliance.

This paper proposes a novel image segmentation method based on Clausius entropy and adaptive Gaussian mixture model for detecting moving objects in a complex environment. The results suggest that the proposed method performs better than existing methods in extracting the foreground in various video sequences composed of multiple objects, lighting reflections, and background clutter.

We propose LPDD (Lifetime Prediction Directed Diffusion), a novel energy-aware routing protocol for sensor networks that aims at increasing network survivability without a significant increase in latency. The key concept behind the protocol is the adaptive selection of routes by predicting the battery lifetime of the minimum energy nodes along the routes.

In this paper, we consider wireless powered sensor networks. In these networks, the energy access point (EAP) transmits the energy packets to the sensor nodes and then, the sensor nodes send their sensing data to the information access point (IAP) by exploiting the harvested energy. Because the sensor nodes have a limited information queue (data storage) and energy queue (battery), energy packet/data packet scheduling is important. Accordingly, to reduce the total energy required to support the associated sensor network and simultaneously avoid sensing data loss, the energy packet/data packet transmission periods are jointly optimized. Furthermore, analyses identify the optimal location of EAP which will yield energy-efficient wireless powered sensor networks. Through the computer simulations, the performance of the proposed packet scheduling and deployment policy is demonstrated.

This letter proposes a new adaptive filtering method that uses the last L desired signal samples as an extra input vector, besides the existing input data, to reduce mean square error. We have improved the convergence rate by adopting the squared norm of the past error samples, in addition to the modified cost function. The modified variable error-data normalized step-size least mean square algorithm provides fast convergence, ensuring a small final misadjustment. Simulation results indicate its superior mean square error performance, while its convergence rate equals that of existing methods. In addition, the proposed algorithm shows superior tracking capability when the system is subjected to an abrupt disturbance.

Side scan sonar using low frequency can quickly search a wide range, but the images acquired are of low quality. The image super resolution (SR) method can mitigate this problem. The SR method typically uses sparse coding, but accurately estimating sparse coefficients incurs substantial computational costs. To reduce processing time, we propose a region-selective sparse coding based SR system that emphasizes object regions. In particular, the region that contains interesting objects is detected for side scan sonar based underwater images so that the subsequent sparse coding based SR process can be selectively applied. Effectiveness of the proposed method is verified by the reduced processing time required for image reconstruction yet preserving the same level of visual quality as conventional methods.

An element consist of a slot and a post is designed for canceling the reflection in a rectangular waveguide by the method of moments. For reducing the computation time in practical design of the element with a wide range of coupling strength for an array, only the axial uniform currents on the post surface are considered. This approximation is valid when the post for reflection-canceling is far enough from the slot. The post location is determined by this simple analysis for both transverse and longitudinal slots with typical coupling strength. Measured results using 4 GHz-band standard waveguides reveal that the assumption of uniform line currents on the post surface is acceptable. The design is further extended to demonstrate its applicability to a practical array design by considering a wide range of coupling strength.

The IEEE 802.15.4 standard enables a short range, low data rate and low power communication between devices in wireless sensor networks (WSNs). In IEEE 802.15.4, a slotted carrier sensing multiple access with collision avoidance (CSMA/CA) algorithm is employed to coordinate a large number of sensor devices. Unlike IEEE 802.11 wireless LAN (WLAN), energy consumption requirements enable it to use fewer number of backoffs, which adversely increase collisions, resulting in degradation of energy consumption. In this letter, we devise an adaptive backoff scheme in WSN whose backoff range is adjusted depending on the contention level, and present its Markov model for mathematical analysis. The proposed scheme is analyzed and its efficiency is validated by ns-2 simulation in respect to network throughput and energy consumption. Its performance is also compared with the standard and previous works, showing that it outperforms them for a whole range of arrival rate.

Providing workflow function is one of the most important research issues in the next generation Internet services such as Web Service and Grid Computing. Scalability for Internet scale services, reliability for unstable Internet resources, and management functions of workflow systems are the essential requirements in these environments. However, existing workflow enactment models for enterprises could not meet these requirements. This paper proposes the PeerFlow that is a P2P based workflow enactment model, to provide workflow functions for the next generation Internet services. To apply P2P model to the workflow enactment model, we introduce the concept of the instance buddy and the index data of workflow instances, then propose the principle architecture of the PeerFlow. The instance buddy enables the autonomous processing of peers, and it is used for recovery and monitoring functions. This paper also presents the recovery capabilities of PeerFlow with formal proofs for the reliability issues and a performance evaluation with SimPy, the Python simulation package.

We consider uplink multi-carrier code-division multiple access (MC-CDMA) systems in a multi-cell environment. It is assumed that all intra-cell users employ Alamouti's simple space-time block coding (STBC), which is known to the base station receiver, but the receiver has no information on whether inter-cell users employ STBC or not. In this case we propose a blind adaptive minimum output energy (MOE) receiver for uplink STBC MC-CDMA, which is designed to perfectly remove the interference from intra-cell users by using the spreading sequence information on all intra-cell users and to reduce the interference from inter-cell users by minimizing the constrained output energy. Analysis and simulation results show that the proposed adaptive receiver has a faster convergence rate and higher steady-state signal-to-interference plus noise ratio (SINR) than a conventional scheme in which only the spreading code information of the desired user is utilized.

Similarity search in time-series databases finds such data sequences whose changing patterns are similar to that of a query sequence. For efficient processing, it normally employs a multi-dimensional index. In order to alleviate the well-known dimensionality curse, the previous methods for similarity search apply the Discrete Fourier Transform (DFT) to data sequences, and take only the first two or three DFT coefficients as organizing attributes. Other than this ad-hoc approach, there have been no research efforts on devising a systematic guideline for choosing the best organizing attributes. This paper first points out the problems occurring in the previous methods, and proposes a novel solution to construct optimal multi-dimensional indexes. The proposed method analyzes the characteristics of a target time-series database, and identifies the organizing attributes having the best discrimination power. It also determines the optimal number of organizing attributes for efficient similarity search by using a cost model. Through a series of experiments, we show that the proposed method outperforms the previous ones significantly.

Guarantees of quality-of-service (QoS) in the real-time transmission of video on the Internet is a challenging task for the success of many video applications. The Internet Engineering Task Force (IETF) has proposed the Guaranteed Service (GS) in the Integrated Service model with firm delay and bandwidth guarantees. For the GS, it is necessary to provide traffic sources with the capability of calculating the traffic characteristics to be declared to the network on the basis of a limited set of parameters statistically characterizing the traffic and the required level of QoS. In this paper, we develop an algorithm for the evaluation of the traffic parameters which characterize the video stream when a QoS requirement is given. To this end an analytical traffic model for the VBR MPEG video is introduced. Simulation results show that the proposed method can evaluate the traffic parameters precisely and efficiently.

The authors propose a novel 3-way power divider named a planar cross-junction, which is used as the center feed for single-layer slotted waveguide arrays. A feeding waveguide consisting of a cascade connection of these dividers is placed at the middle of radiating waveguide in a single layer. The length of radiating waveguides is halved; the long line effect in traveling wave operation is halved and bandwidth is widened. One divider as a unit is designed by Galerkin's method of moments to suppress the reflection and to control the amplitude and the phase of the divided power into two radiating waveguides on both sides of a feed one. Two types of the cross-junction with a different divided power ratio are designed and tested by experiments in 4 GHz band. The mutual coupling effects between two adjacent cross-junctions as cascaded in a feeding waveguide of the array are predicted to be small enough; units designed here are directly applicable for a multiple-way power divider.

This paper describes the measurements made in an urban canyon environment of a relay network scenario to determine the capacity of the multiple-input-multiple-output (MIMO) channel. While varying antenna number and spacing, we measure the channel matrices in the 3.7 GHz band using a 44 switching MIMO channel sounder. The results show that antenna spacing is shown to have less impact than signal-to-noise (SNR) on MIMO channel capacity in a line-of-sight (LOS) environment when physical antenna spacing is selected at four wavelengths. As a result, in an urban MIMO LOS scenario, a base station can provide sufficient data throughput to relay station because most links from base station to relay station have LOS environment and are free from restriction of antenna spacing.

It has been known that the cell loss ratio (CLR) characteristics of the multiplexed traffic depend on the arrangement of I-picture starting times of individual variable bit rate (VBR) MPEG video sources. In this paper, we propose a simple yet accurate traffic model for the multiplexed VBR MPEG video to calculate the CLR at an ATM multiplexer when the arrangement of the I-picture starting times of individual sources is given. In the proposed model, in order to represent the arrangement of the I-picture starting times, each picture type (I-, P-, or B-picture) of individual source is modeled by the arrival rate histogram, and the multiplexed video traffic is modeled by the convolution of the arrival rate histograms of the pictures that comprise the multiplexed traffic. Using the proposed traffic model, we propose an analytical method to calculate the CLR of the multiplexed VBR MPEG video at an ATM multiplexer. Simulation results show that the proposed method can calculate the CLR more precisely and efficiently than other existing methods.

This paper proposes a hardware architecture of programmable controller based on Petri nets. The suggested architecture achieves sufficiently rapid processing even as demands on PCs become increasingly more complex. The architecture's speed and efficiency are derived from an automatic and dynamic super scalar computing capability that executes bit instructions and data handling instructions simultaneously without preprocessing, due to the properties of Petri nets. Specific characteristics for both architectural memory-based implementation of Petri nets and evolution algorithms are suggested and classified by the net structure. Analysis of the suggested architectures and effects on performance are also given with mathematical formulas and a computer simulation.

This paper proposes a genetically inspired adaptive clustering algorithm for numerical and categorical data sets. To this end, unique encoding method and fitness functions are developed. The algorithm automatically discovers the actual number of clusters and efficiently performs clustering without unduly compromising cluster-purity. Moreover, it outperforms existing clustering algorithms.

In this letter, we propose two low complexity algorithms for least square (LS) and minimum mean square error (MMSE) based multi-cell joint channel estimation (MJCE). The algorithm for LS-MJCE achieves the same complexity and mean square error (MSE) performance as the previously proposed most efficient algorithm, while the algorithm for MMSE-MJCE is superior to the conventional ones, in terms of either complexity or MSE performance.

The current letter extends narrow band (NB) local polynomial approximation (LPA) beamforming to wide band (WB) rapidly moving sources. Instead of the conventional beamformer weight in NB LPA, the proposed method adopts the steered minimum variance (STMV) method that can achieve a high resolution with short time observations. The performance of the proposed algorithm is demonstrated via computer simulations.