Ruay-Shiung Chang - Profile on Academia.edu (original) (raw)

Papers by Ruay-Shiung Chang

International Journal of Distributed Sensor Networks, Nov 1, 2013

ZigBee is a protocol suite based upon IEEE standard 802.15.4 for the construction of low-rate wir... more ZigBee is a protocol suite based upon IEEE standard 802.15.4 for the construction of low-rate wireless personal area networks. Since most of ZigBee devices are powered by battery, the power saving is an important issue. In the past several years, many solutions are proposed to extend battery life by reducing device transmitting and receiving time. However, few studies have noticed that most energy is consumed in sensing and monitoring rather than communicating activities, since the data rates in most ZigBee networks are low. Besides, energy will consume the most of those nodes which act as routers or are orphans that cannot join the network. In order to extend the life time of network, we proposed a dynamic topology reformation algorithm. The algorithm consists of a cluster reformation scheme for enhancing connectivity and a self-swapping method for averaging the loading of router nodes and end devices. As the experimental result shows, compared with the ZigBee standard, our method gains 6.02% to 15.13% improvement in network join ratio. And the role swapping balances the power consumption which makes the lifetime of the whole network 1.3 to 1.375 times longer.

Applied sciences, Apr 22, 2021

A quantum key distribution (QKD) network is proposed to allow QKD protocols to be the infrastruct... more A quantum key distribution (QKD) network is proposed to allow QKD protocols to be the infrastructure of the Internet for distributing unconditional security keys instead of existing public-key cryptography based on computationally complex mathematical problems. Numerous countries and research institutes have invested enormous resources to execute correlation studies on QKD networks. Thus, in this study, we surveyed existing QKD network studies and practical field experiments to summarize the research results (e.g., type and architecture of QKD networks, key generating rate, maximum communication distance, and routing protocol). Furthermore, we highlight the three challenges and future research issues in the security of QKD networks and then provide some feasible resolution strategies for these challenges.

Journal of Internet Technology, Dec 1, 2020

Applied Sciences, 2021

International Journal of Distributed Sensor Networks, 2014

Data are generated and updated tremendously fast by users through any devices in anytime and anyw... more Data are generated and updated tremendously fast by users through any devices in anytime and anywhere in big data. Coping with these multiform data in real time is a heavy challenge. Hadoop distributed file system (HDFS) is designed to deal with data for building a distributed data center. HDFS uses the data duplicates to increase data reliability. However, data duplicates need a lot of extra storage space and funding in infrastructure. Using the deduplication technique can improve utilization of the storage space effectively. In this paper, we propose a dynamic deduplication decision to improve the storage utilization of a data center which uses HDFS as its file system. Our proposed system can formulate a proper deduplication strategy to sufficiently utilize the storage space under the limited storage devices. Our deduplication strategy deletes useless duplicates to increase the storage space. The experimental results show that our method can efficiently improve the storage utiliza...

Proceedings of the 4th International Conference on Ubiquitous Information Technologies & Applications, 2009

RFID is a rapid-developing technology for wireless identification lately. How to speed up the pro... more RFID is a rapid-developing technology for wireless identification lately. How to speed up the processing procedure of RFID data is a critical issue needing to be addressed in terms of a real-time RFID application. In order to work out the processing speed problem, Data Grids would be a promising solution to the huge amount of RFID real-time data due to the high performance computing capability and distributed storage system. However, there are still differences between RFID system and Data Grids such as protocols, programming interface, and security issues. Therefore, we suggest an intermediate architecture called RFID-Grid proxy between RFID networks and Data Grids system with a view to interconnecting two different systems. In this architecture, we have evaluated a probabilistic cost estimation model of M/M/m queuing system for RFID jobs considering the system load balance, real-time throughput, and deployment cost.

20th International Conference on Advanced Information Networking and Applications - Volume 1 (AINA'06), 2006

In recent years, there has been a growing interest in wireless sensor networks. One of the major ... more In recent years, there has been a growing interest in wireless sensor networks. One of the major issues in wireless sensor network is developing an energy-efficient routing protocol. Since the sensor nodes have limited available power, energy conservation is a critical issue in wireless sensor network for nodes and network life. Most of the existing routing protocols for sensor networks don't turn off the radio frequency completely. They speed up the energy consumption. LEACH (Low Energy Adaptive Clustering Hierarchy) is a clustering-based protocol that non-cluster-head nodes will turn off their RF completely until their pre-allocated time slot. However, LEACH has a drawback that the cluster is not evenly distributed due to its randomized rotation of local cluster-head. In this paper, we propose a MECH (Maximum Energy Cluster Head) routing protocol. It has self-configuration and hierarchical tree routing properties. MECH improves LEACH in several aspects. MECH constructs clusters based on radio range and the number of cluster members. The cluster topology in the network is distributed more equally through our cluster constructing. We also propose a hierarchical tree routing method that reduces the distance of cluster-head to the base station.

Proceedings 1997 International Conference on Parallel and Distributed Systems

scheme for improving H7TF'CP performance when transmitting through ATM networks. In selective pac... more scheme for improving H7TF'CP performance when transmitting through ATM networks. In selective packet retransmission, we utilize the property of humank perception tolerance for errors to detennine whether to retransmit a corrupted TCP segment or not. For lossable data, such as imagt.. when error occurs because of cell lost, it will not be retransmitted. The simulations show that, f o r the same buffer size and traffics load, seleclive packet retransmission results in higher throughput than PPD, EPD, and plain TCP over ATM.

Concepts, Methodologies, Tools and Applications

With the advancements of computer system and communication technologies, Grid computing can be se... more With the advancements of computer system and communication technologies, Grid computing can be seen as the popular technology bringing about significant revolution for the next generation distributed computing application. As regards general users, a grid middleware is complex to setup and necessitates a steep learning curve. How to access to the grid system transparently from the point of view of users turns into a critical issue then. Therefore, various challenges may arise from the incomprehensive system design as coordinating existing computing resources for the sake of achieving pervasive grid environment. The authors are going to investigate into the current research works of pervasive grid as well as analyze the most important factors and components for constructing a pervasive grid system here. Finally, in order to facilitate the efficiency in respect of teaching and research within a campus, they would like to introduce their pervasive grid platform.

Communications in Computer and Information Science, 2010

In this paper, we propose mobile agent mechanism to efficiently aggregate data on distributed sen... more In this paper, we propose mobile agent mechanism to efficiently aggregate data on distributed sensor networks (DSN), and describe the itinerary of mobile agent to establish by the sink node. The proposal of this mechanism is to reduce consumption of sensor network energy, network bandwidth and the limited resources. This mobile agent mechanism is based on mobile-agentbased DSN (MADSN) which the sink node migrate mobile agent to the sensor node on multicasting based on the binomial tree. It reduces time-cost to aggregate sensor data on MADSN.

2008 IEEE International Symposium on Parallel and Distributed Processing with Applications, 2008

In data grids, replication is a critical technology aiming at lowering the access delay as well a... more In data grids, replication is a critical technology aiming at lowering the access delay as well as saving network bandwidth by duplicating original data in a distributed manner. For data-intensive applications with read/write files, replica consistency is an important issue. In this paper, we propose a novel replica consistency decision model with high adaptability and flexibility using the Naive Bayesian Classifier in order to improve the system performance in data grids. A system prototype has been implemented. The experimental results also prove the excellence of the proposed model.

Mobile cloud computing research - Issues, challenges, and needs

ABSTRACT The rapid advance of mobile computing technology and wireless networking, there is a sig... more ABSTRACT The rapid advance of mobile computing technology and wireless networking, there is a significant increase of mobile subscriptions. This drives a strong demand for mobile cloud applications and services for mobile device users. This brings out a great business and research opportunity in mobile cloud computing (MCC). This paper first discusses the market trend and related business driving forces and opportunities. Then it presents an overview of MCC in terms of its concepts, distinct features, research scope and motivations, as well as advantages and benefits. Moreover, it discusses its opportunities, issues and challenges. Furthermore, the paper highlights a research roadmap for MCC.

International Journal of Distributed Sensor Networks, 2013

On behalf of the Science and Engineering Research Support society (SERSC), it is an honor for us ... more On behalf of the Science and Engineering Research Support society (SERSC), it is an honor for us to introduce you to this special issue, which includes articles that cover topics of particular interest to researchers in the field of sensor technology and applications in industrial control system. This issue contains 18 articles that come from various countries, among which we mention Turkey, USA, Macau, Taiwan, Republic of Korea, Spain, China, and Italy. Achieving such a high quality of papers would have been impossible without the huge work that was undertaken by the External Reviewers. We take this opportunity to thank them for their great support and cooperation. In "Continuous monitoring of water quality using portable and low-cost approaches, " the authors proposed two different approaches for autonomous monitoring of water quality. In the first system, the boats receive trajectories set by the operator before a mission and follow the trajectories to visit predefined sampling points. In the second system, a group of portable water quality probes mounted on buoys at fixed positions regularly analyze water quality and send the data to the control center. Authors proposed a method for correction of frequencysweep nonlinearity in a signal processor instead of linearization of the VCO frequency sweep. For linearization, an additional fixed delay structure was adopted, and the frequency-sweep nonlinearity was extracted and used for compensation in "Correction of nonlinear frequency sweep in frequency-modulated continuous-wave laser range sensor. " The authors validated their linearization method with numerical analysis and computer simulation.

Proceedings of the 2008 ACM symposium on Applied computing, 2008

Taiwan UniGrid (Taiwan University Grid) is a Grid computing platform, which is founded by a commu... more Taiwan UniGrid (Taiwan University Grid) is a Grid computing platform, which is founded by a community of educational and research organizations interested in Grid computing technologies in Taiwan. In this paper, we present the design and development of a middleware for Taiwan UniGrid. Taiwan UniGrid middleware consists of three primary modules: 1) UniGrid Portal, 2) Computing Service, and 3) Data Service. We explain the major design issues that we suffered from the development of these three modules and propose the corresponding approaches to them. The detailed system architecture, software components and features are elaborated. Finally, an example of a workflow consisting of MPI parallel jobs demonstrates that users can utilize Grid resources with ease via our middleware platform.

An Energy-Efficient Clustering Protocol for Wireless Sensor Networks

2010 Second International Conference on Computer and Network Technology, 2010

Abstract In recent years, wireless sensor networks become a new way to obtain information from an... more Abstract In recent years, wireless sensor networks become a new way to obtain information from an interesting area. There are many extensive applications of wireless sensor networks such as environment monitoring, surveillance, enemy tracking, etc. Since the available energy of sensor nodes are limited and hard to renew, energy supervision is critical for nodes and network lifetime in wireless sensor networks. In this paper, we propose a new method to improve ACPM and solve the problem of isolated nodes and to prolong their ...

Lecture Notes in Computer Science, 2009

Wireless Communications and Mobile Computing, 2011

ABSTRACTThe advance of computer network technologies such as IEEE 802.11 wireless local area netw... more ABSTRACTThe advance of computer network technologies such as IEEE 802.11 wireless local area network has made it possible for users to connect to Internet almost anywhere. A mobile node (MN) is likely to move between different base stations while running applications. The IETF has defined the Mobile IP (MIP) to allow MNs to maintain their communication uninterrupted while roaming across different IP subnets. However, the mechanisms defined in MIP may cause undesired connection disruptions or packet losses, which will significantly degrade the quality of real‐time applications. It is an important and challenging issue to support seamless handoff management. To achieve seamless handoff, we propose a unified scheme to address application quality degradation. Our main contribution is the concept and implementation of utilising buffering and resending method to eliminate the packet losses while keeping the end‐to‐end delay of real‐time traffic flow in an acceptable value. The NS‐2 simula...

Wireless Communications and Mobile Computing, 2007

A growing need to have ubiquitous connectivity has motivated our research to provide continuous c... more A growing need to have ubiquitous connectivity has motivated our research to provide continuous connection between various wireless platforms such as cellular networks, WLANs and MANETs. In this paper we consider integration at the routing layer and propose two adaptable routing protocols (IRP-RD and IRP-PD) that exploit topology information stored at the fixed network components (cellular Base Stations and WLAN Access Points) for the route discovery and maintenance processes. Our proposed protocols can provide connectivity to the cellular network and/or WLAN hotspots through multi-hop routing, while differ in the gateway discovery approach used. In IRP-RD, multi-hop routes to gateways to the cellular network or WLAN hot spots are discovered on demand, while in IRP-PD out of coverage users proactively maintain routes to the gateways. Furthermore, proposed protocols can be used in any heterogeneous scenario, combining a cellular network and WLANs operating in infrastructure or ad hoc (MANET) mode. We provide simulation results that demonstrate the effectiveness of the proposed integrated routing protocols and show the advantages and drawbacks of each gateway discovery approach in different heterogeneous scenarios.

Sensors, 2009

The paper considers the connected target coverage (CTC) problem in wireless heterogeneous sensor ... more The paper considers the connected target coverage (CTC) problem in wireless heterogeneous sensor networks (WHSNs) with multiple sensing units, termed MU-CTC problem. MU-CTC problem can be reduced to a connected set cover problem and further formulated as an integer linear programming (ILP) problem. However, the ILP problem is an NP-complete problem. Therefore, two distributed heuristic schemes, REFS (remaining energy first scheme) and EEFS (energy efficiency first scheme), are proposed. In REFS, each sensor considers its remaining energy and its neighbors' decisions to enable its sensing units and communication unit such that all targets can be covered for the required attributes and the sensed data can be delivered to the sink. The advantages of REFS are its simplicity and reduced communication overhead. However, to utilize sensors' energy efficiently, EEFS is proposed. A sensor in EEFS considers its contribution to the coverage and the connectivity to make a better decision. To our best knowledge, this paper is the first to consider target coverage and connectivity jointly for WHSNs with multiple sensing units. Simulation results show that REFS and EEFS can both prolong the network lifetime effectively. EEFS outperforms REFS in network lifetime, but REFS is simpler.

International Journal of Internet Protocol Technology, 2005

In this paper, we propose a new multicast routing protocol, named weight-based clustering multica... more In this paper, we propose a new multicast routing protocol, named weight-based clustering multicast protocol (WCMP), for mobile ad hoc networks. The goal of this work is to improve multicasting performance in ad hoc networks by efficient use of the available knowledge of the networks.