Non‐Data‐Aided Weighted Non‐Coherent Receiver for IR‐UWB PPM Signals

This letter proposes an energy‐detection‐based non‐data‐aided weighted non‐coherent receiver (NDA‐WNCR) scheme for impulse radio ultra‐wideband (IR‐UWB) pulse‐position modulated signals. Compared to the conventional WNCR, the optimal weights of the proposed NDA‐WNCR are tremendously simplified as the maximum eigenvector of the IR‐UWB signal energy sample autocorrelation matrix. The NDA‐WNCR serves to blindly obtain the optimal weights and entirely circumvent the transmission of training symbols or channel estimation in practice. Analysis and simulation results verify that the bit error rate (BER) performance of the NDA‐WNCR closely approaches the ideal BER of the conventional WNCRs.     

Fast Super‐Resolution Algorithm Based on Dictionary Size Reduction Using k‐Means Clustering

This paper proposes a computationally efficient learning‐based super‐resolution algorithm using k‐means clustering. Conventional learning‐based super‐resolution requires a huge dictionary for reliable performance, which brings about a tremendous memory cost as well as a burdensome matching computation. In order to overcome this problem, the proposed algorithm significantly reduces the size of the trained dictionary by properly clustering similar patches at the learning phase. Experimental results show that the proposed algorithm provides superior visual quality to the conventional algorithms, while needing much less computational complexity.     

基于ARM9的英语发音质量评价系统

介绍了基于ARM9嵌入式平台的英语发音质量评价系统的软硬件设计及算法实现。其中,硬件上采用了SBC2440A和philips的UDA1341Ts音频CODEC作为系统主要部分,软件设计包括Linux操作系统的移植、应用程序移植等。算法上实现了从感知、匹配、段长、基音4个方面对语音发音质量进行评价。     

A Biosignal‐Based Human Interface Controlling a Power‐Wheelchair for People with Motor Disabilities

An alternative human interface enabling people with severe motor disabilities to control an assistive system is presented. Since this interface relies on the biosignals originating from the contraction of muscles on the face during particular movements, even individuals with a paralyzed limb can use it with ease. For real‐world application, a dedicated hardware module employing a general‐purpose digital signal processor was implemented and its validity tested on an electrically powered wheelchair. Furthermore, an additional attempt to reduce error rates to a minimum for stable operation was also made based on the entropy information inherent in the signals during the classification phase. In the experiments, most of the five participating subjects could control the target system at their own will, and thus it is found that the proposed interface can be considered a potential alternative for the interaction of the severely disabled with electronic systems.     

Linear‐Time Korean Morphological Analysis Using an Action‐based Local Monotonic Attention Mechanism

For Korean language processing, morphological analysis is a critical component that requires extensive work. This morphological analysis can be conducted in an end‐to‐end manner without requiring a complicated feature design using a sequence‐to‐sequence model. However, the sequence‐to‐sequence model has a time complexity of O(n²) for an input length n when using the attention mechanism technique for high performance. In this study, we propose a linear‐time Korean morphological analysis model using a local monotonic attention mechanism relying on monotonic alignment, which is a characteristic of Korean morphological analysis. The proposed model indicates an extreme improvement in a single threaded environment and a high morphometric F1‐measure even for a hard attention model with the elimination of the attention mechanism formula.     

Statistical Model‐Based Voice Activity Detection Based on Second‐Order Conditional MAP with Soft Decision

In this paper, we propose a novel approach to statistical model‐based voice activity detection (VAD) that incorporates a second‐order conditional maximum a posteriori (CMAP) criterion. As a technical improvement for the first‐order CMAP criterion in [1], we consider both the current observation and the voice activity decision in the previous two frames to take full consideration of the interframe correlation of voice activity. This is clearly different from the previous approach [1] in that we employ the voice activity decisions in the second‐order (previous two frames) CMAP, which has quadruple thresholds with an additional degree of freedom, rather than the first‐order (previous single frame). Also, a soft‐decision scheme is incorporated, resulting in time‐varying thresholds for further performance improvement. Experimental results show that the proposed algorithm outperforms the conventional CMAP‐based VAD technique under various experimental conditions.     

An Immersive Augmented‐Reality‐Based e‐Learning System Based on Dynamic Threshold Marker Method

In recent years, augmented reality (AR) technologies have been the subject of great interest among many communities. In education applications, old‐fashioned materials (or textbooks) are still used, despite remarkable AR developments in the industrial area. We present an AR system for education. Our system consists of an authoring tool that can be used to create educational content, a viewer that plays that content, and an engine to manage the tool and viewer. In our system, a marker unit recognizes a marker printed on a plane or a cubic plane by adaptively adjusting the threshold to have an excellent recognition rate in diverse environments and acquires corresponding data of the marker. Based on the system, we test 142 elementary school students for increased educational benefits using our system.     

Clausius Normalized Field‐Based Stereo Matching for Uncalibrated Image Sequences

We propose a homology between thermodynamic systems and images for the treatment of time‐varying imagery. A physical system colder than its surroundings absorbs heat from the surroundings. Furthermore, the absorbed heat increases the entropy of the system, which is closely related to its disorder as given by the definition of Clausius and Boltzmann. Because pixels of an image are viewed as a state of lattice‐like molecules in a thermodynamic system, the task of reckoning the entropy variations of pixels is similar to estimating their degrees of disorder. We apply this homology to the uncalibrated stereo matching problem. The absence of calibrations alleviates user efforts to install stereo cameras and enables users to freely modify the composition of the cameras. The proposed method is also robust to differences in brightness, white balancing, and even focusing between stereo image pairs. These peculiarities enable users to estimate the depths of interesting objects in practical applications without much effort in order to set and maintain a stereo vision setup. Users can consequently utilize two webcams as a stereo camera.     

Femto‐Second Laser‐Based Free Writing of 3D Protein Microstructures and Micropatterns with Sub‐Micrometer Features: A Study on Voxels,Porosity, and Cytocompatibility

Femto‐second laser‐based free‐writing of complex protein microstructures and micropatterns, with sub‐micrometer features and controllability over voxel dimension, morphology, and porosity, is reported. Protein voxels including lines, spots, and micropillars are fabricated. Laser power, exposure time, z‐position, protein and photosensitizer concentrations, but not scanning speed, are important controlling parameters. A lateral fabrication resolution of ≈200 nm is demonstrated in 2D line voxels. 3D spot voxels are ellipsoids with 400 nm lateral and 1.5 μm axial dimensions. An ascending z‐stack scanning method to verify the theoretical axial optical resolution, delineate and enhance the axial fabrication resolution of 3D structures, including square prism and cylinder micropillars, is also reported. The micropillar array presents a simple “write‐and‐seed” and table platform for cell niche studies. Fibroblasts attach to, grow on, and express adhesion to molecules on micropillar arrays without the need of matrix coating. They exhibit a more “3D” morphology comparing with that in 2D monolayer cultures and physiological functions such as matrix deposition. This work presents an important milestone in engineering complex protein microstructures and micropatterns with sub‐micrometer topological features to mimic the native matrix niche for cell‐matrix interaction studies.     

Synthesis and Multiscale Evaluation of LiNbO3‐Containing Silicate Glass‐Ceramics with Efficient Isotropic SHG Response

A study of bulk second harmonic generation (SHG) response of lithium niobium silicate glass‐ceramics is presented. The observed macroscopic SHG signals have an isotropic 3D nature. To interpret this particular nonlinear optical response, a multiscale approach is used in which clear correlations between structure and optical response are characterized from the sub‐micrometer to the millimeter scale. In particular, it is inferred that the radial distribution of the LiNbO₃ crystallites in spherulite domains is at the origin of the isotropic bulk second order optical property. It is suggested that spherulitic crystallization in glass‐ceramic is a challenging method to elaborate isotropic nonlinear optical properties in inorganic materials.     

基于应用的可见光遥感图像质量评价方法研究

遥感应用需求的增加和应用水平的提高,对遥感图像质量提出越来越高的要求。为提高图像质量,一方面不断改进成像系统,另一方面也研究开发出各种图像处理方法,其中如何评价图像处理前后图像质量的变化是处理算法开发的重要环节。从应用的角度,通过对比评价图像处理前后的质量,初步研究提出了基于图像应用的主、客观评价方法,以找出算法处理的薄弱环节,为算法的优化提供支持。     

Multi‐criteria Evaluation of Mobile Network Sharing Policies in Korea

Mobile operators in saturated markets increasingly favor mobile network sharing (MNS) over facility‐based competition. Previous research examining MNS primarily focused on its positive effects, while the negative effects were largely overlooked. This study proposes a decision‐making model using an analytic hierarchy process technique to evaluate decision‐making criteria among various types of MNS policies. The decision‐making model was applied to Wireless Broadband services in Korea to determine the relative importance of both positive and negative evaluation criteria and preference among multiple types of MNS policies. Positive evaluation criteria (that is, efficiency) were far greater in importance than negative evaluation criteria (that is, competition harm). The preference for adopting MNS among five alternative approaches was also revealed. The study findings offer immediate policy insights in Korea and provide a decision‐making framework for policy makers in other countries to utilize.     

基于机器学习的网络感知评估方法

提升网络感知和客户满意度一直是网络优化的工作主线,而KPI指标无法反映网络真实感知情况,传统通过调研了解客户满意度的方式存在很大局限性。本文深入研究了KPI指标和网络真实感知的映射关系,通过大数据挖掘和机器学习建模实现了感知权重因子的量化,以此为基础完成了一种基于机器学习的网络感知评估方法,为客户满意度提升工作提供了全新的分析思路和支撑手段。     

PKG‐VUL: Security Vulnerability Evaluation and Patch Framework for Package‐Based Systems

In information security and network management, attacks based on vulnerabilities have grown in importance. Malicious attackers break into hosts using a variety of techniques. The most common method is to exploit known vulnerabilities. Although patches have long been available for vulnerabilities, system administrators have generally been reluctant to patch their hosts immediately because they perceive the patches to be annoying and complex. To solve these problems, we propose a security vulnerability evaluation and patch framework called PKG‐VUL, which evaluates the software installed on hosts to decide whether the hosts are vulnerable and then applies patches to vulnerable hosts. All these operations are accomplished by the widely used simple network management protocol (SNMP). Therefore, system administrators can easily manage their vulnerable hosts through PKG‐VUL included in the SNMP‐based network management systems as a module. The evaluation results demonstrate the applicability of PKG‐VUL and its performance in terms of devised criteria.     

Peak‐to‐average power ratio reduction of a hidden training sequence‐aided precoding scheme for MIMO‐OFDM

We analyze a peak‐to‐average power ratio (PAPR) reduction property based on a hidden training sequence‐aided precoding scheme for MIMO‐OFDM systems. In addition to the benefits of a hidden training sequence‐aided precoding scheme such as improvement in bandwidth efficiency and frequency diversity gain, we address that power amplifier efficiency can be improved without any additional complexity burden. By mathematically analyzing PAPR of the precoded MIMO‐OFDM signal with a hidden training sequence, we demonstrate that PAPR reduction can be obtained by varying the allocated power to the hidden training sequence. Because of the low PAPR property of this scheme, it is possible to utilize a low‐cost power amplifier, resulting in the reduction in the total cost for hardware implementation. Copyright © 2014 John Wiley & Sons, Ltd.     

Fabrication of All‐Water‐Based Self‐Repairing Superhydrophobic Coatings Based on UV‐Responsive Microcapsules

Superhydrophobic coatings that are also self‐healing have drawn much attention in recent years for improved durability in practical applications. Typically, the release of the self‐healing agents is triggered by temperature and moisture change. In this study, UV‐responsive microcapsules are successfully synthesized by Pickering emulsion polymerization using titania (TiO₂) and silica (SiO₂) nanoparticles as the Pickering agents to fabricate all‐water‐based self‐repairing, superhydrophobic coatings. These coatings are environmentally friendly and can be readily coated on various substrates. Compared to conventional superhydrophobic coatings, these coatings can regenerate superhydrophobicity and self‐cleaning ability under UV light, mimicking the outdoor environment, after they are mechanically damaged or contaminated with organics. They can maintain the superhydrophobicity after multiple cycles of accelerated weathering tests.     

Bienenstock,Cooper, and Munro Learning Rules Realized in Second‐Order Memristors with Tunable Forgetting Rate

Memristors with synaptic functions are very promising for developing artificial neural networks. Compared with the extensively reported spike‐timing‐dependent plasticity (STDP), Bienenstock, Cooper, and Munro (BCM) learning rules, the most accurate model of the synaptic plasticity to date, are more compatible with the neural computing system; however, the progress in the realization of the BCM rules has been quite limited. The realized BCM rules so far mostly performs just the spike‐rate‐dependent plasticity (SRDP), however, without a tunable sliding frequency threshold, because the memristors used to realize the BCM rules do not have tunable forgetting rates. In this work, the BCM rules with a tunable sliding frequency threshold are biorealistically implemented in SrTiO₃‐based second‐order memristors; the forgetting rate of the memristors is tuned by engineering the electrode/oxide interface through controlling the electrode composition. The approach of this work is precise and efficient, and the biorealistic implementation of the BCM rules in memristors improves the efficiency of the neural network for the artificial intelligent system.     

Evaluation of an ultra‐wide bandwidth wireless indoor non‐line‐of‐sight channels

In this paper, based on the analysis of the experimental data using a new post‐processing method for time‐domain channel measurements, a new double‐cluster statistical model for UWB systems with a bandwidth lower than 1 GHz in non‐line‐of‐sight (NLOS) indoor propagation environment is proposed. By using the proposed model, both the model itself and the parameter estimation of the corresponding model are simplified. By defining the polarity of a particular model parameter, the model has the flexibility to deal with both ‘soft NLOS’ and ‘hard NLOS’ indoor propagation environments. Therefore, the channel impulse responses (CIRs) generated by the proposed model ‘resemble’ the measured CIR better than the SV (Saleh‐‐Valenzuela)/IEEE 802.15.3a model not only in terms of the average values, but also in terms of the cumulative distribution functions (CDFs) of the small‐scale statistics. Copyright © 2008 John Wiley & Sons, Ltd.     

Measurement Accuracy of Oscillation‐Based Test of Analog‐to‐Digital Converters

Oscillation‐based testing of analog‐to‐digital converters represents a viable option for low‐cost built‐in self‐testing in mixed‐signal design. While numerous papers have addressed implementation issues, little attention has been paid to the measurement accuracy. In this letter, we highlight an inherent measurement uncertainty which has to be considered when deriving the parameters from the oscillation frequency.