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Image encryption technique has been actively researched and improved. Double Random Phase Encryption (DRPE), known as the typical way of optical encryption, can easily encrypt images. In the decryption process of DRPE, the complex conjugate of random phase mask used as the encryption key in the Fourier domain is used as the decryption key. As a result, computational DRPE has a vulnerability in image transmission when the random phase mask is stolen. Our proposed method utilizes the random function defined by the sender, and it generates additional random variable to multiply the random phase mask. Finally, our proposed method can enhance the security of the encryption process. However, the random phase mask and random variable information generated by random function are needed to decrypt the image. To send both information, high cost is required in the transmission process. To overcome this problem, our proposed method sends the conjugate random phase mask and random function to the receiver for the decryption process. Finally, our proposed method can enhance security with a low transmission cost., 13th International Conference on ITC Convergence (ICTC2021), October 20-22, 2021, Jeju, Korea

In this study, vertical tunnel FET-based ternary CMOS (T-CMOS) is introduced and its electrical characteristics are investigated using TCAD device and mixed-mode simulations with experimentally calibrated tunneling parameters. This new T-CMOS utilizes two different types of tunneling currents to form three different output voltage states: (1) source-to-drain tunneling current; and (2) conventional source-to-channel tunneling current. To form a half supply voltage ( $\text{V}_{DD}$ ) output voltage during the inverter operation, the n-/p-type devices of the proposed T-CMOS are designed to have constant source-to-drain tunneling current regardless of gate voltage ( $\text{V}_{GS}$ ) by using nitride spacer between gate and drain. Also, typical binary inverter operation is performed using the source-to-channel tunneling. In voltage transfer characteristics (VTC), it is confirmed that there is the clear half $\text{V}_{DD}$ state after matching the tunneling currents of the n-/p-type devices. It is revealed that the stable half $\text{V}_{DD}$ state cannot be achievable if the currents are mismatched by gate workfunction, gate dielectric thickness, and interface trap variations, implying that the current matching between n-/p-type devices is crucial to obtain stable ternary operations.

In this article, an investigation has been performed to statistically analyze the entire subthreshold characteristics of tunnel field-effect transistor (TFET) depending on a gate work function variation (WFV). Firstly, the current variations are evaluated through turn-on voltage ( ${V} _{\mathrm{ ON}}$ ) and threshold voltage ( $V_{T}$ ) with help of technology computer-aided design (TCAD) simulation. Secondly, the variation of $V_{T}$ and ${V} _{\mathrm{ ON}}$ are quantitatively analyzed by coefficient of determination ( ${R} ^{2}$ ) in the regression analysis. The ${R} ^{2}$ values are extracted according to the divided the gate prats. Finally, it is confirmed that the WFV of the gate parts causes the current variation in areas where tunneling is varied mainly according to the gate bias.

In recent years, it has been shown that intense THz pulses are powerful tools to manipulate, deflect or accelerate ultrashort electron bunches. The THz range is of interest, since the corresponding wavelengths are well-matched to a typical electron bunch size of several tens of microns. Here, we propose to use split-ring resonators (SRR) as key-elements to realize various tasks in electron accelerators. Through a judicious choice of shape and geometry these structure exhibit a considerable near-field enhancement, boosting the incident THz field strength by a factor of ten or more.

Nanosheet FETs (NSFETs) are expected as future devices that replace FinFETs beyond the 5nm node. Despite the importance of the devices, few studies report the impact of NSFETs in the full-chip level. Therefore, this paper presents NS3K, the first 3nm NSFET library, and presents the results in a full-chip scale. Based on our results, 3nm NSFET reduces power by −27.4%, total wirelength by −25.8%, number of cells by −8.5%, and area by −47.6% over 5nm FinFET, respectively, due to better devices and interconnect scaling. However, careful device/layout designs followed by routing-resource considering standard cells are required to maximize the advantages of 3nm technology.

With great growth in the volume of chemical databases, machine learning receives significant attention from various scientific communities for efficient high-throughput screening of molecular properties and drug discovery on the millions of chemical compounds. In particular, graph neural networks (GNNs) have been widely studied in chemistry-related fields because a molecule is natively represented as a mathematical graph. In GNNs for the graph-level analysis, a global operation called readout is applied after node embedding to generate a graph-level embedding that represents characteristics of the whole graph. However, commonly used readouts frequently distort scale information of the graph and consequently degrade the prediction accuracy of GNNs. This problem becomes more serious in molecular machine learning because molecules have many important scale information (e.g., molecular weight and total energy). In this paper, we investigate this scale distortion problem in GNNs caused by the readouts for the first time and propose an efficient solution with a new attention-based readout. In the experiments, the proposed readout outperformed commonly used readouts on various GNN architectures.

In High-Speed Serial Interface (HSSI) IP using AC coupled configuration, due to the AC coupled configuration, it can cause unexpected issues that cannot screen fail chips. That is, external loopback test is not able to reject the fail chip, even if one of the differential positive and negative signals is abnormal status, such as pin floating or open. This paper proposes a cost effective test method can screen unexpected failure without measurement performance degradation assisted by simple circuit modification and additional test sequence.

Auto-stereoscopic displays using slanted optical plates have inherent subpixel rasterization compared to the normal 2D displays, and mappings between subpixel positions and multi-view indices even vary according to the number of views and angles of slanted optical plates. In this paper, we derive a simple but generalized formula for subpixel mappings from a naïve ray-tracing technique on RGB stripe type panels. To verify the proposed algorithm, our proto-type auto-stereoscopic display using parallax barriers with a slanted angle was used and examined in the experiment. The proposed algorithm is expected to leverage converting multi-view 3D inputs to various types of auto-stereoscopic contents in real time., 2nd International Conference on Artificial Intelligence in Information and Communication (ICAIIC 2020), February 19-21, 2020, Fukuoka, Japan

In this paper, we present a novel traffic accident detection method using a spatio-temporal three-dimensional (3D) convolutional neural network. The proposed method consists of pre-activation ResNet and feature pyramid network (FPN) structure. To reduce computational load with preserving the detection accuracy, we propose interval input method. Experimental results show that the proposed network outperforms existing methods in the sense of both precision and recall measures.

A high voltage circuit breaker was mainly used to prevent accidents that may occur during transmission and distribution. The specifications of circuit breaker and energy of mechanism were decided by voltage and current level. It is important to satisfy electric and mechanical performance of circuit breaker. In mechanical performance, the reliability of circuit breaker is related to the IEC 62271-102 standards. The mechanical endurance of interrupter is M2 class and the number of operating cycles is 10,000. In past, the repeated tests were performed to satisfy the reliability of circuit breaker, so the time and cost were very high. To reduce the time and cost, there were many studies that predict the dynamic behavior and reliability of circuit breaker. In this study, the dynamic loads were measured to analyze 550kV circuit breaker. The multibody dynamic analysis models were developed by using RecurDyn program. And the simulation results were validated with experimental results. The fatigue analysis and evaluation were executed by using simulation and experimental results.

In this talk, we introduce the novel technique for real-time measurement of a ultrafast optical field by utilizing the relativistic electron beam. The direct electron-field interaction of our real-time oscilloscope guarantees the signal integrity of THz waveform measurement with a sampling rate of 75 Ts/s.

We propose a novel regularization algorithm to train deep neural networks, in which data at training time is severely biased. Since a neural network efficiently learns data distribution, a network is likely to learn the bias information to categorize input data. It leads to poor performance at test time, if the bias is, in fact, irrelevant to the categorization. In this paper, we formulate a regularization loss based on mutual information between feature embedding and bias. Based on the idea of minimizing this mutual information, we propose an iterative algorithm to unlearn the bias information. We employ an additional network to predict the bias distribution and train the network adversarially against the feature embedding network. At the end of learning, the bias prediction network is not able to predict the bias not because it is poorly trained, but because the feature embedding network successfully unlearns the bias information. We also demonstrate quantitative and qualitative experimental results which show that our algorithm effectively removes the bias information from feature embedding., CVPR 2019, Accepted

As demanding the ultrashort bunches for the pump & probe experiments to investigate ultrafast phenomena occurring at atomic size level, the diagnostic tools should be developed to measure. by measuring the electron diffraction pattern directly. We have developed an S-band RF deflecting cavity working on $\mathrm{TM}_{120}$ mode to measure the femto-second bunch duration of electron beam in UED (Ultrafast Electron Diffraction) system at KAERI. In this conference, we will present on design, fabrication and experimental performance of the deflecting cavity. The estimated temporal resolution of RF deflector, operating with the deflecting voltage of 1.5 MV and the drift length of 1.7 m, is 50 fs. The electron beam with 3 MeV and 1.88 pC, electron bunch duration has 67 fs in rms, which is well agreed with the simulation results.

In this paper, we present an implementation of a smart scale that can measure a subject’s weight, heart rate and detect atrial fibrillation (AF). For weight measurement, four load cell sensors are used. For measuring heart rates and detecting AF, PSL-iECG2 is used. Load cell sensors and PSL-iECG2 are connected to Arduino Uno. As Arduino Uno has not enough computing power to analyze ECG signals and determine AF, Arduino Uno is connected to smartphone in Bluetooth. From the ECG signals, R peaks are extracted and using the R-R intervals, heart rates are calculated. AF is detected using RMSSD and Shannon entropy extracted from R-R intervals. We evaluate three classifiers that are kNN, DT, and NNs. The accuracies of each classifier for detecting AF are 83.7%, 83.7%, and 89.1%, respectively.

Various methods have been researched with acoustic tests for diagnosing and evaluating voice disorder. The acoustic method of voice evaluation has been widely studied with the acoustic analyzer. However, it is necessary to visit a hospital equipped with an expensive acoustic analyzer. To solve this problem, we propose a smartphone-based acoustic analyzer. In this paper, three different acoustic indicators were measured, using Jitter, Shimmer, and NHR. Based on the acoustic indicators, experiments were conducted on healthy and unhealthy subjects to evaluate voice quality. The collected data set is clustered using cobweb clustering method. The risk of vocal disorders can be predicted by measuring the distance and direction between the centroids.

In this talk, we introduce our ultrashort electron accelerator facility and recent efforts for the THz-based temporal diagnostics of electron bunch. The THz-driven electron streak camera with a resolution of sub-10 femtoseconds is demonstrated by using the metallic split-ring resonator (SRR).

This paper presents a new type of anthropomorphic robot bionic eyes. Most existing eye mechanisms are serial mechanism and have no degree of freedom (DOF) for eye roll, however, the serial mechanism is not compact enough and the eye roll movement is crucial for image stabilization, consequently, we design a 3 DOFs compact serial-parallel eye mechanism which can implement the eye spherical movements without eccentricity, the diameter of the eyeball is only 45 mm, the total weight of the eye mechanism is 300 g, each of the eye contains two cameras (long and short focal length lens) for mimicking the perception features of human eyes. We also design a 3 DOFs serial neck mechanism for improving the flexibility and the ability of image stabilization of the robot bionic eyes. The neck and each of the eye contain inertial sensors, the robot bionic eyes can implement the vestibuloocular reflex like hybrid image stabilization function in two-stage by using the neck and eye mechanisms. The robot bionic eyes contain completely the same number of DOFs with human which is beneficial to human-robot interaction.

By changing curing accelerator and modifying the volume resistivity of epoxy molding compound (EMC), electrostatic characteristics of EMC applied package can be improved and electrostatic damage of IC device was reduced. EMC with phosphonium salt accelerator results in much lower ESD failure than EMC with phosphine salt accelerator. Because the volume resistivity of phosphonium salt applied EMC is lower than that of phosphine salt, it could easily dissipate the static electricity that generated inside of package during or after transfer molding process.

This video shows the line tracking control performance of two balancing mobile robots that have two wheels. Two balancing mobile robots form a master-slave configuration that the master robot follows the line and the slave robot follows the master. Two robots are equipped with a camera to detect lines on the playgrounds. Real demonstration of following the line by the master-slave balancing mobile robot has been presented in CIRO(Creative and Intelligent RObot Contest) 2015 held in Daejeon.

A performance of circuit breaker is dependent on the dynamic behavior of spring operating mechanism (SOM) in terms of mechanical system. The response speed of the circuit breaker is one of important part in the performance of circuit breaker and the response speed of the circuit breaker was determined by latch mechanism. The latch mechanism consists of solenoid actuator and several linkages with joints and springs. In this paper, the design variables were selected by using sensitivity analysis and design of experiment (DOE). The optimum design was executed and the response time was reduced. To validate the optimum value, the simulation results were compared the experimental results which were measured using a high speed camera. The simulation and experimental results were similar in reduced time.

A circuit breaker is widely used to protect electric power system from fault of electric currents or system errors. In this study, a circuit breaker with spring operating mechanism operated by the stored elastic energy of the close spring was addressed. In case of the closing mechanism of this circuit breaker, the torque generated by closing spring rotates the closing shaft. A cam which is located on the closing shaft axis rotates the opening shaft. Several linkages are moved by cam-follower mechanism. In this case, rotating cam is important component for transferring energy generated by closing spring energy. In this paper, multibody dynamic model of a circuit breaker including switch mechanism and cam-follower mechanism was developed using ADMAS. To validate the developed model, the closing velocity of simulation and experiment results was compared. With the developed multibody dynamic model, cam profile optimization was conducted. Cam profile was constructed by spline function including design points. Each point was calculated by radius according to regular interval angle in polar coordinate. Design sensitivity analysis and optimization of cam profile was conducted for decreasing the closing velocity after contacting interrupt.

A performance of a high-voltage circuit breaker is mainly dependent on the mechanical efficiency of spring operating mechanism. To predict the performance of the circuit breaker, the analysis of the performance of the circuit breaker is required. In this paper, the analysis model including friction and efficiency of spring was developed to predict a dynamic behavior of circuit breaker. The analysis model was developed by using 1-D based multi-physics tool, the friction and efficiency of spring were measured by using an electric linear actuator, a hydrostatic actuator and a high speed camera. The friction and efficiency of spring were acquired in experiment, the acquired data were applied in analysis model. The simulation results were compared to experimental results in dynamic behavior of circuit breaker. Hence, it is possible to predict the dynamic characteristics of the circuit breaker.

Since the performance of a circuit breaker which has the spring operating mechanism mainly depends on the dynamic behavior of a coil spring, the analysis of the dynamic behavior of a coil spring is required for a performance evaluation of a circuit breaker. When a spring moves so fast from the releasing state, a lot of energy is used to move a self-weight of a spring. In this study, a release test bed is designed for evaluating the dynamic behaviors of a coil spring. From the release tests, the dynamic behaviors of a coil spring are analyzed. RecurDyn is employed to carry out the computer simulation and results are compared with test results. The actual energy transferred to the follower during high-speed motion is analyzed through the comparisons of the kinetic energy between the experiment and the computer simulation.

This paper proposes a power conditioning system (PCS) for distributed photovoltaic (PV) applications using a hybrid asymmetric cascaded multilevel inverter with a single PV source. One of the main disadvantages of cascaded multilevel inverters in PV systems is the requirement of multiple isolated DC sources which leads to voltage unbalancing. The proposed PCS uses a single PV source with a flyback DC-DC converter to facilitate the reduction of the required DC sources and maintain voltage balance. The flyback converter is used to provide the input for low voltage H-bridge cell which processes only 20% of the total power. This helps to minimize the losses occurring in the proposed PCS. Furthermore, transient analysis and controller design for the proposed PCS in stand-alone mode of operation is presented. The feasibility of the proposed PCS has been tested using a 1kW hardware prototype and the obtained results are presented.

Recently wireless sensor networks have been used as the technology that is actively grafted onto industries and daily living. Sensors should have built-in routing functions and basic sensing functions for the self-configuration of topologies. The number of sensors necessary for using them in an actual observation ranges from tens to hundreds or thousands. When theses sensors are wrongly placed in an observation region, they can quickly run out of batteries or be disconnected. These incidents may result in huge losses in terms of sensing data from numerous sensors and their costs. Therefore a number of simulators have been developed as tools for effective design and verification before the actual arrangement of sensors. While a number of simulators have been developed, simulation results can be fairly limited and the execution speed can be markedly slow depending on the function of each simulator. To improve the performance of existing simulators, this paper aimed to develop a parallel processing simulator for separate sensor (P2S3) that enables users to selectively use the GPU mode. It enables parallel and independent operations by matching GPU with many cores in order to resolve the slowdown of the execution speed when numerous sensor nodes are used for simulations. Also, P2S3 include the analyzed of sensor nodes with log data and visualization. The P2S3 supports the GPU mode in an environment that allows the operation of compute unified device architecture (CUDA), and performs the parallel simulation processing of multiple sensors using the mode within a short period of time.

In this paper, high-efficiency, extremely high step-up and step-down bi-directional DC-DC converter is proposed. The proposed converter consists of a flyback and an isolated switched-capacitor cell to achieve high cost competitiveness for the extreme operation. The output of the flyback converter and that of the isolated switched-capacitor is connected in series to obtain a high voltage step-up. In the reverse direction, then, this converter can be an extremely voltage step-down one. For the design of the controller, the small-signal transfer functions of the converter are derived. Finally, a 100W hardware prototype of the proposed converter is implemented. To improve the efficiency of a PV system employing the proposed converter, a maximum Power Point Tracking (MPPT) method is applied with Perturb and Observe (P&O) method. To demonstrate the operation of the bidirectional converter, the main switch current is used for the power control. All of these controls are implemented with a digital signal processor (DSP).

In this paper, a new path-planning algorithm is proposed based on inverse kinematics (IK) and end effector maximum mobility direction. As a fundamental tool, the IK is used in many fields, forexample, path planning. In order to find the manipulator configuration, first, a 5-DOF humanoid manipulator IK solver is obtained and verified. If the end effector moves along the maximum mobility direction, the motion generation efficiency in the Cartesian space is optimal. However, the maximum mobility direction is defined locally for the current configuration of the manipulator. If the start configuration and the traveling time are pre-determined, the path can be determined uniquely, and the end effector may not reach the precise goal position. Therefore, a unit direction vector is used for revising the direction and making the end effector move close to the goal position. The simulation results demonstrate the effectiveness of this path-planning algorithm.

In this paper, we propose a method to detect a main speaker and automatically change into one's high definition (HD) video for a distributed telepresence system, so that the users feel immersive and convenient. In contrast to centralized systems, user equipment (UE) performs the main speaker decision (MSD) with a time synchronization using network time protocol (NTP). The MSD method includes a voice activity detection (VAD) and post-corrections to remove unwanted voice detections and share the same main speaker. We emphasize an audio signal of the main speaker to become more immersive. The proposed approach is applied to the telepresence system developed by ETRI and shows good performances.

This paper discusses on the balance control of bicycle robot. The reaction wheel pendulum is used to control the balance. The PID controller, based on the non-model, is used. The performance of controller is confirmed by the experiment.

Accurate cardiac signal monitoring feasible for long-term monitoring is important for a practical, cost-effective health monitoring system. In this study, we propose a wearable healthcare system based on conductive fabric-based electrodes allowing monitoring of electrocardiogram (ECG) waveforms and demonstrated the potential for arrhythmia detection using the system. The measurement system uses conductive fabric-based electrodes arranged in a modified bipolar electrode configuration on the chest area of the patient. An adaptive impulse correlation filter (AICF) algorithm and a band pass filter to enable accurate R-peak detection in noisy environments.

Most of research groups have studied on Tunneling Field-Effect Transistors (TFETs) with assumption that there are no gate/source overlap and abrupt source/channel junction. In this work, we study the electrical characteristics of double-gated thin-body TFET with gate/source overlap and no abrupt source/channel junction. From transfer characteristics, hump phenomenon occurring with increasing gate bias is observed. This phenomenon affects the threshold voltage (VTH), which worsens device matching and also makes it difficult to design logic circuits. The reason why tunneling current is suddenly increased is due to tunneling components in a direction normal to the channel. Theses hump phenomena are not seen in the previous TFET study using unidirectional nonlocal band-to-band tunneling model.

The threshold voltage (VT) control of gate-all-around (GAA) MOSFETs as an extreme case of multi-gate MOSFETs is studied. After breaking down the components constituting VT into several terms, their relative sizes are compared using TCAD technique and analytical calculation of quantum mechanical problem. As a result, the channel diameter is found to be an important knob to control VT of a GAA MOSFET, which influences on short-channel effect, quantum confinement effect and other effects.

This paper proposes a 3D map-building algorithm using one LRF (Laser Range Finder) while a mobile robot is navigating on the slanted surface. There are several researches on 3D map buildings using the LRF. However most of them are performing the map building only on the flat surface. While a mobile robot is moving on the uneven surface, which makes it very difficult to build the 3D map using encoder data. To cope with the dynamic change of the view angle in build 3D map, IMU and balance filters are combined to measure the accurate height in this research. Through the real navigation experiments, it is verified that the fusion of multiple sensors are properly performed to correct the slope angle of the uneven surface. The effectiveness of the balance filter are also checked through the hill climbing navigations. Thus, a single LRF, IMU sensor and the balance filter by using, it is possible to draw three-dimensional map on uneven surface.

L-shaped tunneling field-effect transistors (TFETs) feature high current drivability and abrupt on-off transition. For further improvement of L-shaped TFETs, tunneling regions become n-type doped in this study. The doping concentration of the tunneling regions is optimized. The proposed novel L-shaped TFETs show higher on-current (I on ) and lower subthreshold swing (SS) than conventional L-shaped TFETs.

In this paper, a single LRF has been used to produce a 3D map for the mobile robot navigation. The 2D laser scanners are used for mobile robots navigation, where the laser scanner is applied to detect a certain level of area by the straight beam. Therefore it is limited to the usages of 2D obstacle detection and avoidance. In this research, it is designed to complement a mobile robot system to move up and down a single LRF along the yaw axis. During the up and down motion, the 2D data are stacked and manipulated to build a 3D map. Often a single LRF data are mixed with a lot of noises, it's like Gaussian and Impulse. The noises are removed out by the superposition median filter designed in this research. The 2D data which are improved by deleting the noises are layered to build the 3D map. Removing impulse noises while preserving the boundary is a main advantages of the SMF (Superposition Median Filter) which has been used widely to improve the quality of images. The effectiveness of this SMF for rejecting the noise has been verified through the real experiments.

In this paper, hump effects of L-shaped tunneling field-effect transistors (TFETs) have been investigated. It turns out that the hump effects are originated from the two different turn-on voltages (V turn-on 's). By using device simulation, the source junction design has been optimized in order to suppress the hump effects.

Supply voltage (V DD ) scaling has been an important issue as the CMOS scaling down. Scaling of devices induces large leakage current due to Short Channel Effects (SCEs). Also, Subthrehold Swing (SS) value of CMOS devices is theoretically limited to 60 mV/dec. Various structures have been proposed to overcome power dissipation problems, one of which is the TFETs [1–2]. However, TFET has two critical drawbacks such as low on-current level and ambipolar behaviors. To overcome these disadvantages, TFET using hetero-gate dielectric materials has been lately reported [3]. Although this TFET has low SS and high on-current level, it is difficult to control dielectric alignment between high-k material and SiO 2 in the process. Thus, we introduce an improved TFET in terms of fabrication and performance.

Modern VLSI technology has been developed with continuous scaling of MOSFET. However, as MOSFET has been scaled down, a lot of critical issues have risen and resulted in a considerable degradation of individual devices [1]. On the other hand, owing to its periodic on/off characteristic, single-electron transistor (SET) attracts attention with its promising performance. But, in general, fabricating SET, silicon-on-insulator (SOI) wafers have been used for their leakage current through buried oxide (BOX) on the substrate region [2]. However, in this paper, we propose a vertical structure that is fabricated on a bare wafer, not on a SOI wafer, and the fabrication process with which small size of a quantum dot (QD) can be formed more easily than previous works [1][3]. Since the smaller QD a SET has, the better operation characteristic it has at room temperature (RT), the characteristic of the SET device can be observed more clearly than previous works with the simple process to downsize a QD.

As complementary metal oxide semiconductor (CMOS) has been scaled down and supply voltage has been reduced, it becomes important to reduce subthreshold swing (SS) in order to obtain high on/off current ratio. To decrease SS below 60 mV/dec, tunneling field effect transistor (TFET) has been reported and studied recently[1–3]. However, as TFET uses band-to-band tunneling as its current source, it is difficult to obtain high on-current. In order to solve this problem of the conventional TFET and maintain high on-current while lowering SS, novel device using p-n junction gate is proposed in this paper.

In this paper, a new algorithm for encoding spectral envelope in G.729.1 for VoIP is proposed. In the TDAC part of G.729.1, the spectral envelope and MDCT coefficients extracted in the weighted CELP coding error (lower-band) and the higher-band input signal are encoded. In order to reduce allocation bits for spectral envelope coding, a new algorithm using sub-band correlation between adjacent frames is proposed. In addition, a new bit allocation strategy using reduced bits from the proposed algorithm is also proposed. The performance of the proposed algorithm is evaluated by sound quality and bit reduction rates in clean and frame loss conditions.

With the fast proliferation of the mobile Internet, the wireless community has been increasingly looking for a framework that can provide seamless mobility. In this paper, we propose a fast cross-layer handover scheme based on movement prediction in mobile WiMAX environment. Prediction is achieved by auto-regressive integrated moving average (ARIMA(p,d,q))model. The orders of the model parameters are estimated from the signal strength samples of mobile users. By utilizing signal strength prediction, layer-3 handover activities are able to occur prior to start of layer-2 handover procedure, and therefore, total handover latency and service disruption time can be reduced. The experiments conducted with system parameters and propagation model defined by WiMAX Forum demonstrate that the proposed method predicts the future signal level accurately and reduces the total handover latency and packet drop probabilities.

The DARPA Network Challenge was a nationwide exercise in the use of social media in extreme events. Teams competed to locate ten red weather balloons that DARPA tethered over public locations across the continental United States for seven to ten hours on Saturday, December 5, 2009. The MIT team won the event, finding all ten locations using monetary incentive and a multi-level marketing payout scheme. This paper outlines the methods used by the 10th place iSchools Caucus team, which used a combination approach of recruiting observers and the use of Open Source Intelligence (OSINT) to find six of the ten locations. Twitter feeds and publicly available content on competing team websites were captured. Data from these mechanisms were evaluated for content validity using a combination of secondary observers, evaluation of the reputation of reported observers and confirmation of the true identities and locations of reporting individuals by mining additional data from several social networking sites. These methods may have application in law enforcement, homeland security and extreme events when there is a desire to use humans as soft sensors, but where it is impossible to directly recruit observers or motivate them with financial incentives.

While a tunneling field-effect transistor (TFET) is an attractive candidate for sub-20 nm ultra-low-power device, high I ON /I OFF and on-current are rarely reported with the deep-submicron structures. In this study, we propose a practical novel TFET structure with vertical channel and Ge junction, which shows high current ratio, low subthreshold swing and relatively high current even when the minimum device dimension is smaller than 20 nm. To find the optimum design, the off-state injection of a short-channel TFET and optimization of the source-side junction are studied by simulation.