Browsing by Author "Zao, John K."

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A Geometrically Faithful Memetic Algorithm for Searching Sparse Representations of EEG Signals
(2012)
Qiu, Jun-Wei
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Zao, John K.
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Chou, Yu-Hsiang
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資訊工程學系
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Department of Computer Science
This paper presents a memetic algorithm, christened the natural memetic pursuit (NMP), that was designed to search for sparse signal representations. This algorithm combines global sampling based on a Grassmannian dictionary of atomic signals with local search using natural gradient decent in the signal parameter space. Performance of the algorithm was demonstrated by analyzing Jung and Makig's ERP data sets. It can obtain unbiased sparse representations of EEG signals in far less iteration than its predecessor, the stochastic matching pursuit (SMP).
A Practical Optimization Framework for the Degree Distribution in LT Codes
(2013-11-01)
Chen, Chih-Ming
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Chen, Ying-Ping
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Shen, Tzu-Ching
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Zao, John K.
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資訊工程學系
LT codes are the first practical rateless codes whose reception overhead totally depends on the degree distribution adopted. The capability of LT codes with a particular degree distribution named robust soliton has been theoretically analyzed; it asymptotically approaches the optimum when the message length approaches infinity. However, real applications making use of LT codes have finite number of input symbols. It is quite important to refine degree distributions because there are distributions whose performance can exceed that of the robust soliton distribution for short message length. In this work, a practical framework that employs evolutionary algorithms is proposed to search for better degree distributions. Our experiments empirically prove that the proposed framework is robust and can customize degree distributions for LT codes with different message length. The decoding error probabilities of the distributions found in the experiments compare well with those of robust soliton distributions. The significant improvement of LT codes with the optimized degree distributions is demonstrated in the paper.
A rate-distortion optimization model for SVC inter-layer encoding and bitstream extraction
(2008-12-01)
Peng, Wen-Hsiao
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Zao, John K.
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Huang, Hsueh-Ting
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Wang, Tse-Wei
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Huang, Lin-Shung
The Scalable Video Coding (SVC) standard enables viewing devices to adapt their video reception using bitstream extraction. Since SVC offers spatial, temporal, and quality combined scalability, extracting proper bitstreams for different viewing devices can be a non-trivial task, and naive choices usually produce poor playback quality. In this paper, we propose a two-prong approach to achieve rate-distortion (R-D) optimal extraction of SVC bitstreams. For SVC encoding, we developed a set of adaptation rules for setting the quantization parameters and the inter-layer dependencies among the SVC coding layers. A well-adapted SVC bitstream thus produced manifests good R-D trade-offs when its scalable layers are extracted along extraction paths consisting of successive refinement steps. For extracting R-D optimized bitstreams for different viewing devices, we formalized the notion of optimal and near-optimal extraction paths and devised computationally efficient strategies to search for the extraction paths. Experiment results demonstrated that our R-D optimized adaptation schemes and extraction strategies offer significant improvement in playback picture quality among heterogeneous viewing devices. Particularly, our adaptation rules promise R-D convexity along optimal extraction paths and permit the use of steepest-descent strategy to discover the optimal/near-optimal paths. This simple search strategy performs only half of the computation necessary for an exhaustive search. (C) 2008 Elsevier Inc. All rights reserved.
Activity-oriented design of Health Pal: A smart phone for elders' healthcare support
(2008)
Zao, John K.
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Fan, Shih-Chen
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Wen, Ming-Hui
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Hsu, Chun-Tang
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Hung, Chung-Hoo
Wireless telephones and personal digital assistants are emerging, as the information hubs connect their human users with assorted electronic devices and the World Wide Web. As such, they quickly become the de facto basis for personalized information services. The Kannon project team at the National Chiao Tung University (NCTU) in Taiwan is developing a ubiquitous service infrastructure for elders' healthcare support. Among their deliverables, there is a PDA Phone, christened Health Pal, which can communicate with Bluetooth/ZigBee devices, universal plug-and-play (UPnP) e-home service platforms, and online healthcare providers to offer 24/7 healthcare services to elderly people. This paper presents the early results of this effort including the functional and operational concepts of Health Pal as well as the activity-oriented approach of its design. Preliminary results of its usefulness and usability evaluations are reported. A comparison of this platform against several similar prototypes was also included to illustrate the advantage of applying activity-oriented design approach to human-computer interactions. Copyright (C) 2008.
An Error-Floor Reduction Technique for Short-Length LT Codes
(2014-01-01)
Chang, Li-Jen
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Wang, Chung-Hsuan
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Zao, John K.
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資訊工程學系
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電機資訊學士班
Luby transform (LT) codes are often employed during best-effort packet transfers to offer rateless erasure protection. Efficient as they are, these randomized codes with a small number of input symbols often post an inevitable performance trade-off between the decoding failure rates in their waterfall and error-floor regions. In order to surmount this trade-off, we propose a new encoding strategy that requires a portion of the high-degree output symbols of an LT code to abandon the conventional equally-probable input selection strategy; instead, connect themselves to some specially selected low-degree input symbols. Our simulation results show that shortlength LT codes with merely 10(3) input symbols yield significantly lower symboVhlock failure rates at a small overhead of reception as they employ the proposed strategy. These performanceenhanced rateless codes can have potential applications in realtime multimedia broadcasting.
An fMRI Study of Abrupt-Awake Episodes during Behavioral Microsleeps
(2011)
Chou, Yu-Hsiang
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Chuang, Chun-Chao
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Zao, John K.
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Ko, Li-Wei
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Lin, Chin-Teng
This paper reports the brain activation patterns of five subjects who were abruptly awakened from microsleeps in a simulated automotive driving experiment. By comparing the BOLD signals between behavioral microsleep (BM), abrupt awakening (AA) and post-abrupt awakening (post-AA) stages, we observed that visual area, frontal cortex, limbic lobe manifested more intense activation during the AA stage while frontal cortex, temporal cortex, primary motor area and insula were more activated during the post-AA stage. These results suggested that the subjects were likely in mental states differ from those associated with decision making processes as they went through and emerged from the abrupt awakening episodes.
Augmenting VR/AR Applications with EEG/EOG Monitoring and Oculo-Vestibular Recoupling
(2016-01-01)
Zao, John K.
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Jung, Tzyy-Ping
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Chang, Hung-Ming
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Gan, Tchin-Tze
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Wang, Yu-Te
Head-mounted virtual reality and augmented reality displays (a. k. a. VR/AR goggles) created a revolutionary multimedia genre that is seeking ever-broadening applications and novel natural human interfaces. Adding neuromonitoring and neurofeedback to this genre is expected to introduce a new dimension to user interaction with the cyber-world. This study presents the development of a Neuromonitoring VR/AR Goggle armed with electroencephalo- gram and electrooculogram sensors, programmable milli-Ampere current stimulators and wireless fog/cloud computing support. Beside of its potential use in mitigating cybersickness, this device may have potential applications in augmented cognition ranging from feedback-controlled perceptual training to on-line learning and virtual social interactions. A prototype of the device has been made from a Samsung Gear VR for S6. This study explains its technical design to ensure precision data sampling, synchronous event marking, real-time signal processing and big data cloud computing support. This study also demonstrates the effective-ness in measuring the event-related potentials during a visual oddball experiment.
Consistent Sparse Representations of EEG ERP and ICA Components Based on Wavelet and Chirplet Dictionaries
(2010)
Qiu, Jun-Wei
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Zao, John K.
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Wang, Peng-Hua
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Chou, Yu-Hsiang
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資訊工程學系
a randomized search algorithm for sparse representations of EEG event-related potentials (ERPs) and their statistically independent components is presented. This algorithm combines greedy matching pursuit (MP) technique with covariance matrix adaptation evolution strategy (CMA-ES) to select small number of signal atoms from over-complete wavelet and chirplet dictionaries that offer best approximations of quasi-sparse ERP signals. During the search process, adaptive pruning of signal parameters was used to eliminate redundant or degenerative atoms. As a result, the CMA-ES/MP algorithm is capable of producing accurate efficient and consistent sparse representations of ERP signals and their ICA components. This paper explains the working principles of the algorithm and presents the preliminary results of its use.
Customizing short-length LT codes with evolution strategies for video streaming protection
(2017-07-01)
Hornansky, Martin
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Zao, John K.
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資訊工程學系
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Department of Computer Science
Designing short-length Luby Transform (SLLT) codes to best protect video streaming and multicasting over lossy communication remains largely an empirical exercise. In this paper, we present a systematic approach to customize the decoding performance of these codes so that the protected video bitstreams may have the best playback quality over a wide range of channel loss rates. Our approach begins with the proposal of a new SLLT decoding performance model based on three parameters: decoding overhead, symbol decoding failure rate and tail probability of symbol decoding failure rate. We then formulate the design of SLLT codes as a multi-objective optimization problem, specify the design objectives in terms of goal program, and search for the most suitable codes using an augmented weighted Tchebycheff method implemented with the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). Two design examples are provided to illustrate the effectiveness of our approach: (1) an SLLT postcode of a short-length raptor code that provides erasure protection to H.264 AVC bitstreams, and (2) an SLLT post-code of a rateless UEP code that supports graceful degradation of H.264 SVC playback quality. Empirical results demonstrate that the proposed method is capable of producing SLLT codes with customized decoding performance, whereas, the customized codes enable the playback pictures to attain significantly higher PSNR values at different stages of the decoding process than the pictures recovered under the protection of conventionally optimized codes.
Custos Remote On-demand Healthcare Aided with Wireless Sensors and Mobile Phones
(2008)
Zao, John K.
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Fan, Shih-Chen
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Yang, Bing-Shiang
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Hsu, Shang-Hwa
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Cheng, Han-Chin
Telemonitoring and remote healthcare are two ICT techniques promise to deliver cost effective long-term healthcare services to the aging population worldwide. Anticipating an emerging market opportunity, NCTU Kannon project team is creating Custos, an open composeable platform for developing remote on-demand healthcare applications using smart phones and wireless sensor networks. Camps' is integrated readily with Internet web services and UPnP digital-home platform so that it can be used to detect abnormal health conditions through multisensor data fusion, adapt environment conditions to user needs, dispatch medical alerts and instigate remedial actions via SMS/RSS communication. Moreover, Custos is easy to program because it uses Sun SPOT and Squawk Java J2ME as its sensor/actuator hub. In this position paper, we present the design principles, system architecture and operation concepts of Custos as well as a pilot plan for clinical trials in the Geriatric Psychiatry Ward of Wei-Gong Memorial Hospital in Miaoli, Taiwan.
Design of Optimal Short-Length LT Codes Using Evolution Strategies
(2012)
Zao, John K.
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Hornansky, Martin
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Diao, Pei-lun
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資訊工程學系
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Department of Computer Science
Luby Transform (LT) and its companion Raptor codes are the most popular implementations of digital fountain codes. Performance of these rateless forward erasure correction codes is determined mainly by the degree distributions of their encoded symbols. Although the asymptotic behaviors of LT codes with large (>10(5)) symbol blocks have been deduced analytically, a proficient method for finding the optimal degree distributions of short length (<10(3)) LT codes is still absent. In this paper, we propose a practical approach to employ evolution strategies in finding the degree distributions of optimal short-length LT codes for different applications. Our approach begins with the development of a new performance model for LT codes based on three measurements: coding overhead epsilon, failure ratio r and failure occurrence probability p. Three evolution strategies (DE, CMA-ES and NES) were then employed to minimize these performance measurements separately with careful design of fitness functions and necessary transformations of decision variables. Throughout the evolution process, the performance of individual LT code in the population was evaluated with numerical simulations. Our experiments showed that the optimal degree distributions can be found using all three evolution strategies but with different convergence rates and the (r, p, epsilon) values of these optimized codes are all distributed on a smooth concave surface.
Detecting Glaucoma With a Portable Brain-Computer Interface for Objective Assessment of Visual Function Loss
(2017-06-01)
Nakanishi, Masaki
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Wang, Yu-Te
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Jung, Tzyy-Ping
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Zao, John K.
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Chien, Yu-Yi
IMPORTANCE The current assessment of visual field loss in diseases such as glaucoma is affected by the subjectivity of patient responses and the lack of portability of standard perimeters. OBJECTIVE To describe the development and initial validation of a portable brain-computer interface (BCI) for objectively assessing visual function loss. DESIGN, SETTING, AND PARTICIPANTS This case-control study involved 62 eyes of 33 patients with glaucoma and 30 eyes of 17 healthy participants. Glaucoma was diagnosed based on a masked grading of optic disc stereophotographs. All participants underwent testing with a BCI device and standard automated perimetry (SAP) within 3 months. The BCI device integrates wearable, wireless, dry electroencephalogram and electrooculogram systems and a cellphone-based head-mounted display to enable the detection of multifocal steady state visual-evoked potentials associated with visual field stimulation. The performances of global and sectoral multifocal steady state visual-evoked potentials metrics to discriminate glaucomatous from healthy eyes were compared with global and sectoral SAP parameters. The repeatability of the BCI device measurements was assessed by collecting results of repeated testing in 20 eyes of 10 participants with glaucoma for 3 sessions of measurements separated by weekly intervals. MAIN OUTCOMES AND MEASURES Receiver operating characteristic curves summarizing diagnostic accuracy. Intraclass correlation coefficients and coefficients of variation for assessing repeatability. RESULTS Among the 33 participants with glaucoma, 19 (58%) were white, 12 (36%) were black, and 2 (6%) were Asian, while among the 17 participants with healthy eyes, 9 (53%) were white, 8 (47%) were black, and none were Asian. The receiver operating characteristic curve area for the global BCI multifocal steady state visual-evoked potentials parameter was 0.92 (95% CI, 0.86-0.96), which was larger than for SAP mean deviation (area under the curve, 0.81; 95% CI, 0.72-0.90), SAP mean sensitivity (area under the curve, 0.80; 95% CI, 0.69-0.88; P = .03), and SAP pattern standard deviation (area under the curve, 0.77; 95% CI, 0.66-0.87; P = .01). No statistically significant differences were seen for the sectoral measurements between the BCI and SAP. Intraclass coefficients for global and sectoral parameters ranged from 0.74 to 0.92, and mean coefficients of variation ranged from 3.03% to 7.45%. CONCLUSIONS AND RELEVANCE The BCI device may be useful for assessing the electrical brain responses associated with visual field stimulation. The device discriminated eyes with glaucomatous neuropathy from healthy eyes in a clinically based setting. Further studies should investigate the feasibility of the BCI device for home-based testing as well as for detecting visual function loss over time.
Efficient Authentication of Resource-Constrained IoT Devices based on ECQV Implicit Certificates and Datagram Transport Layer Security Protocol
(2016-01-01)
Duy An Ha
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Kha Tho Nguyen
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Zao, John K.
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交大名義發表
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National Chiao Tung University
This paper introduces a design and implementation of a security scheme for the Internet of Things (IoT) based on ECQV Implicit Certificates and Datagram Transport Layer Security (DTLS) protocol. In this proposed security scheme, Elliptic curve cryptography based ECQV implicit certificate plays a key role allowing mutual authentication and key establishment between two resource-constrained IoT devices. We present how IoT devices get ECQV implicit certificates and use them for authenticated key exchange in DTLS. An evaluation of execution time of the implementation is also conducted to assess the efficiency of the solution.
Fog as a Service Technology
(2018-11-01)
Chen, Nanxi
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Yang, Yang
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Zhang, Tao
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Zhou, Ming-Tuo
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Luo, Xiliang
Fog computing has emerged as a promising solution for the loT and next generation mobile networks. As an extension to cloud computing, it enables service provisioning along the continuum from the cloud to things to reduce latency and bandwidth demands, and empower end users in their vicinity. Such a cloud-to-thing service continuum requires full technology support in infrastructure, platform, software and service levels. This article proposes FA(2)ST and its architecture to underpin a multi-level system of fog computing services for end-to-end support of loT applications. It presents the concept of FA(2)ST and describes its architecture, main features, a use case in a vertical industry, and a performance study.
Habituation of Steady-State Visual Evoked Potentials in response to High-Frequency Polychromatic Foveal Visual Stimulation
(2013)
Kuo, Heng-Yuan
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Chiu, George C.
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Zao, John K.
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Lai, Kuan-Lin
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Gruber, Allen
In an attempt to develop safe and robust methods for monitoring migraineurs\' brain states, we explores the feasibility of using white, red, green and blue LED lights flickering around their critical flicker fusion (CFF) frequencies as foveal visual stimuli for inducing steady-state visual evoked potentials (SSVEP) and causing discernible habituation trends. After comparing the habituation indices, the multi-scale entropies and the time dependent intrinsic correlations of their SSVEP signals, we reached a tentative conclusion that sharp red and white light pulses flickering barely above their CFF frequencies can replace commonly used 13Hz stimuli to effectively cause SSVEP habituation among normal subjects. Empirical results showed that consecutive short bursts of light can produce more consistent responses than a single prolonged stimulation. Since these high frequency stimuli do not run the risk of triggering migraine or seizure attacks, further tests of these stimuli on migraine patients are warranted in order to verify their effectiveness.
Halo: A Hierarchical Identity-Based Public Key Infrastructure for Peer-to-Peer Opportunistic Collaboration
(2009)
Tseng, Fu-Kuo
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Zao, John K.
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Liu, Yung-Hsiang
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Kuo, Fang-Po
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資訊工程學系
The lack of information security protection for peer-to-peer systems has hampered the use of this robust and scalable technology in sensitive applications. The security weakness is rooted in the server-less architecture and the demand driven ad-hoc operation scenarios of peer-to-peer systems. Together, they prohibit scalable key management using traditional symmetric/asymmetric cryptographic techniques. The advent of hierarchical identity-based cryptography and thresholded/joint secret sharing offers a possible solution to this problem. In this paper, we present the design of Halo, a hierarchical identity-based public key infrastructure that uses these novel technologies to perform recursive instantiation of private key generators and establish a trust hierarchy with unlimited number of levels. The PKI thus enables the employment of hierarchical identity-based public key encryption, signature, and signcryption for the protection of peer-to-peer applications. The effort to implement a proof-of-concept prototype as a JXTA service module was also discussed.
Integrating Non-Repetitive LT Encoders With Modified Distribution to Achieve Unequal Erasure Protection
(2013-12-01)
Yen, Kuo-Kuang
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Liao, Yen-Chin
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Chen, Chih-Lung
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Zao, John K.
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Chang, Hsie-Chia
The performance of LT code is highly related to the code length. A decoder is more likely to deplete degree-1 encoding symbols and terminate during early stage when the code length is short. In this work, we modify the robust Soliton distribution (RSD) and increase the degree-1 proportion. More degree-1 encoding symbols can be generated to relieve early decoding termination. The proportion of low degrees, except for degree-1, is also reduced. Therefore, receivers collect less encoding symbols carrying redundant information. In addition, Non-Repetitive (NR) encoding scheme is proposed to avoid producing repeated degree-1 encoding symbols. To improve video transmission quality, previous studies redesign LT codes to provide Unequal Error Protection (UEP) for different Scalable Video Coding (SVC) layers. Unlike those studies to modify the code structure, we integrate multiple NR encoders to achieve UEP ability. Experimental results show that our UEP scheme outperforms previous studies in terms of the PSNR.
Kannon: Ubiquitous Sensor Actuator technologies for elderly living and care - A Multidisciplinary Effort in National Chiao Tung University, Taiwan
(2006)
Zao, John K.
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Hu, Jwu-Sheng
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Chiou, Jin-Chern
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Huang, Yu-Lun
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Li, Shu-Chen
A team of researchers including computer scientists, electrical and control engineers, architects, industrial designers, human factor engineers, and cognitive scientists in the National Chiao Tung University (NCTU), Taiwan, along with their overseas collaborators launched the project Kannon, a multidisciplinary effort to develop Adaptive Assistive Technologies that can be deployed incrementally into existing private/public spaces and collaborate opportunistically to offer monitoring, assisting, communicating and rejuvenating services to healthy elders. The team combined the state-of-art information, communication and robotic know-how with the activity oriented method for product design and the modular functional approach in modern architecture in order to devise a holistic support for successful aging. This paper presents the philosophy, approach and first fruits of this project.
MULTIDIMENSIONAL SVC BITSTREAM ADAPTATION AND EXTRACTION FOR RATE-DISTORTION OPTIMIZED HETEROGENEOUS MULTICASTING AND PLAYBACK
(2008)
Peng, Wen-Hsiao
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Zao, John K.
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Huang, Hsueh-Ting
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Wang, Tse-Wei
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Kuo, Lun-Chia
In this paper, we propose an optimal SVC bitstream extraction scheme that can produce scalable layer representations for different viewing devices scattered over a multicasting network with diverse link bandwidth. Our scheme can determine optimal extraction orders/paths that are implementable at different multicasting nodes by performing successive steps of multiple adaptation. In addition to this basic scheme, we also develop an unambiguous denotation for the optimal extraction paths, and an algorithm for deducing the optimal extraction paths for less capable devices through path truncation. Extensive SVC encoding and adaptation experiments have been performed using JSVM 9 and both objective quality metrics (PSNR and MSE) as well as subjective metric (VQM). The experiment results showed that our scheme works well if convexity of R-D performance is maintained throughout the SVC bitstream.
Natural User Interfaces: Cyber-Physical Challenges and Pervasive Applications A Panel Discussion
(2014)
Zao, John K.
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Lin, Chin-Teng
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Ko, Li-Wei
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She, Hsiao-Ching
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Dung, Lan-Rong
This panel discussion aims at exploring the potential applications of emerging natural user interface (NUI) technologies and the challenges they pose to the design and deployment of cyber-physical systems. Based on their research work, six panelists will take turns to present the outlook, the cyberphysical requirements and the promising applications of implicit NUI. We hope these short presentations will lead to thought-provoking discussions and inspire further innovation.