Browsing by Author "Liu, Xiao-Long"

Now showing 1 - 9 of 9

A file-deduplicated private cloud storage service with CDMI standard
(2016-02-01)
Liu, Xiao-Long
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Sheu, Ruey-Kai
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Yuan, Shyan-Ming
;
Wang, Yu-Ning
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資訊工程學系
The emergence of cloud environments makes users convenient to synchronize files across platform and devices. However, the data security and privacy are still critical issues in public cloud environments. In this paper, a private cloud storage service with the potential for security and performance concerns is proposed. A data deduplication scheme is designed in the proposed private cloud storage system to reduce cost and increase the storage efficiency. Moreover, the Cloud Data Management Interface (CDMI) standard is implemented in the proposed system to increase the interoperability. The proposed service provides an easy way to for user to establish the system and access data across devices conveniently. The experiment results also show the superiority of the proposed interoperable private cloud storage service in terms of data transmission and storage efficiency. By comparing with the existing system Gluster Swift, the proposed system is demonstrated much suitable for the service environment where most of the transmitted data are small files. (C) 2015 Elsevier B.V. All rights reserved.
A novel reversible data hiding scheme based on AMBTC compression technique
(2015-06-01)
Lin, Chia-Chen
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Liu, Xiao-Long
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Tai, Wei-Liang
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Yuan, Shyan-Ming
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資訊工程學系
Data hiding encompasses a wide range of applications for embedding messages in content. However, hiding data inevitably destroys the host image, even though the distortion is imperceptible. To enhance the hiding capacity and maintain the quality of the host image after embedding hidden data, in this paper, we present a high payload reversible data hiding scheme that is based on the absolute moment block truncation coding (AMBTC) compression domain. We explore the redundancy in a block of AMBTC-compressed images to determine if a block is embeddable or non-embeddable. Next, we create four disjoint sets for embeddable blocks to embed data using different combinations of the mean value and the standard deviation. Performance comparisons with other BTC-based schemes are provided to demonstrate the superiority of the proposed scheme.
An Architecture for Cloud Service Testing and Real Time Management
(2015)
Lo, Win-Tsung
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Liu, Xiao-Long
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Sheu, Ruey-Kai
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Yuan, Shyan-Ming
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Chang, Chun-Yu
Cloud service testing ensures that services run properly and meet the Service Level Agreement (SLA) requirements. However, performance problems of a cloud service, such as the availability and reliability, are difficult to diagnose because these issues might be caused from different system components. To solve these problems, this study proposes an architecture for testing environment configuration and quality estimation for both of fault diagnosis and bottleneck detection. The proposed system has two components: offline testing and online management. In offline testing, target service are tested by using the proposed testing module and corresponding metrics are collected for further analysis. The analyzed results which are separated between fault diagnosis and bottleneck detection will be stored in knowledge databases. Finally, online management module will automatically suggest how to do when facing this kind of problem according to knowledge based diagnosis.
An Optimal Modified BTC Scheme based on Binary Search Tree
(2014-01-01)
Lin, Chia-Chen
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Liu, Xiao-Long
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Zhou, Jian-Jie
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Yuan, Shyan-Ming
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資訊工程學系
With the purpose of improving the visual quality of an original block truncation coding (BTC) compressed image, an optimal modified BTC scheme (OMBTC) is proposed. The binary search tree (BST) technique is utilized to determine the optimal quantization of each image block. The proposed scheme is compared with several existing modification BTC schemes; the experimental results demonstrate that the proposed scheme can preserve high image quality after compression.
Auto-Scaling Mechanism for Cloud Resource Management Based on Client-Side Turnaround Time
(2016)
Liu, Xiao-Long
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Yuan, Shyan-Ming
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Luo, Guo-Heng
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Huang, Hao-Yu
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資訊工程學系
Currently, providers of Software as a service (SaaS) can use Infrastructure as a Service (IaaS) to obtain the resources required for serving customers. SaaS providers can save substantially on costs by using resource-management techniques such as auto scaling. However, in most current auto-scaling methods, server-side system information is used for adjusting the amount of resources, which does not allow the overall service performance to be evaluated. In this paper, a novel auto-scaling mechanism is proposed for ensuring the stability of service performance from the client-side of view. In the proposed mechanism, turnaround time monitors are deployed as clients outside the service, and the information collected is used for driving a dynamic auto-scaling operation. A system is also designed to support the proposed auto scaling mechanism. The results of experiments show that using this mechanism, stable service quality can be ensured and, moreover, that a certain amount of quality variation can be handled in order to allow the stability of the service performance to be increased.
Blind Dual Watermarking for Color Images' Authentication and Copyright Protection
(2018-05-01)
Liu, Xiao-Long
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Lin, Chia-Chen
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Yuan, Shyan-Ming
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資訊工程學系
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Department of Computer Science
This paper presents a blind dual watermarking mechanism for digital color images in which invisible robust watermarks are embedded for copyright protection and fragile watermarks are embedded for image authentication. For the purpose of copyright protection, the first watermark is embedded using the discrete wavelet transform in YCbCr color space, and it can be extracted blindly without access to the host image. However, fragile watermarking is based on an improved least significant bits' replacement approach in RGB components for image authentication. The authenticity and integrity of a suspicious image can be verified blindly without the host image and the original watermark. The combination of robust and fragile watermarking makes the proposed mechanism suitable for protecting valuable original images. The experimental results indicated that the proposed watermarking mechanism can withstand various processing attacks and accurately locate the tampered area of an image.
Fragile Watermarking-based Authentication Scheme for Demosaicked Images
(2015)
Lin, Chia-Chen
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Liu, Xiao-Long
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Lin, Cheng-Han
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Yuan, Shyan-Ming
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資訊工程學系
This paper presents a reversible fragile watermarking scheme for the authentication of demosaicked images. Each authentication code is embedded into the two rebuilt components of each color pixel by using a designed authentication table (ACT). The utilization of ACT secures the watermarking procedure and the watermarked image can be recovered back to the original demosaicked image by the proposed scheme. The proposed scheme is compared with some existing image authentication schemes, and the experimental results demonstrate that our scheme can preserve better image quality and provides superior tamper detection performance.
Knee Point-Driven Bottleneck Detection Algorithm for Cloud Service System
(2016)
Liu, Xiao-Long
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Zhang, Xue-Bai
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Chao, Hsiang
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Yuan, Shyan-Ming
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資訊工程學系
Currently, providers of Software as a service (SaaS) can use Infrastructure as a Service (IaaS) to obtain the resources required for serving customers. Performance problems in a SaaS system are difficult to diagnose, because they may be caused by various system components. This study proposes a knee point-driven bottleneck detection algorithm, the specific resource bottleneck in the target system can be detected by analyzing the collected metrics. The detection result provides a scale up recommendation for the service provider to facilitate reconfiguring the service system. The experimental results revealed that the proposed system can detect a potential bottleneck in a service system accurately. After solving the detected bottleneck the performance of the target cloud service can be improved efficiently.
Reversible data hiding for VQ-compressed images based on search-order coding and state-codebook mapping
(2015-02-01)
Lin, Chia-Chen
;
Liu, Xiao-Long
;
Yuan, Shyan-Ming
;
資訊工程學系
;
Department of Computer Science
In the field of digital multimedia, numerous researchers have exploited data hiding for providing secure communications. Because most multimedia is compressed in advance to save storage space and transmission time, this paper presents a reversible data-hiding scheme for vector quantization (VQ)-compressed images. In the proposed scheme, search-order coding (SOC) is first employed to reduce the size of the VQ index table. For image blocks that cannot be processed by SOC, a technique called state-codebook mapping (SCM) is used to map the blocks to the corresponding indices in their state-codebooks, which are generated by a set of neighborhood indices. After SOC and SCM, the size of the output code stream is reduced, and a large amount of space is available for embedding sensitive data. Performance comparisons with similar recent studies are presented for demonstrating the superiority of the proposed scheme. The experimental results indicated that the proposed scheme can achieve a high embedding capacity and a high compression bit rate. (C) 2014 Elsevier Inc. All rights reserved.