Vol. 2, No. 1, Feb. 2006
Yoon-Seok Jeong, Tae-Wan Kim, Sun Young Han, Chun-Hyon Chang
Vol. 2, No. 1, pp. 1-5, Feb. 2006
Keywords: Timing Constraint Search Technique, TMO Real-Time Process Load Model, Network Load Model
Show / Hide AbstractFinding a valid timing constraint is one of the most important issues in the real-time monitoring area. To get the valid timing constraint, a developer executes a real-time process and changes the constraint on a regular basis. This is an exhaustive and time-consuming process. To improve this approach, we propose a timing constraint search technique. This technique uses two load models and one condition proposed in this paper to support the developer in determining the valid timing constraint range in an easy and systematic manner.
Server Selection Schemes Considering Node Status For a Fault-Tolerant Streaming Service on a Peer-to-Peer NetworkHyunjoo Kim, Sooyong Kang, Heon Y. Yeom
Vol. 2, No. 1, pp. 6-12, Feb. 2006
Keywords: Peer-to-peer network, Fault-tolerant streaming services
Show / Hide AbstractPeer-to-Peer (P2P) networks are attracting considerable research interest because of their scalability and high performance relative to cost. One of the important services on a P2P network is the streaming service. However, because each node in the P2P network is autonomous, it is difficult to provide a stable streaming service on the network. Therefore, for a stable streaming service on the P2P network, a fault-tolerant scheme must be provided. In this paper, we propose two new node selection schemes, Playback Node First (PNF) and Playback Node First with Prefetching (PNF-P) that can be used for a service migration-based fault-tolerant streaming service. The proposed schemes exploit the fact that the failure probability of a node currently being served is lower than that of a node not being served. Simulation results show that the proposed schemes outperform traditional node selection schemes.
Heawon Kang, Sung-Hwan Jung
Vol. 2, No. 1, pp. 13-17, Feb. 2006
Keywords: audio watermarking, blind detection Wavelet
Show / Hide AbstractIn this paper, we propose an audio extraction method to decrease the influence of the original signal by modifying the watermarking detection system proposed by P. Bassia et al. In the extraction of the watermark, we employ a simple mean filter to remove the influence of the original signal as a preprocessing of extraction and the repetitive insertion of the watermark. As the result of the experiment, for which we used about 20 kinds of actual audio data, we obtain a watermark detection rate of about 95% and a good performance even after the various signal processing attacks.
Ji-Seung Nam, Hui Gao, Mi-Young Kang, Kyoung-Tae Kim, Seung-Chul Son, Chung-Ung Pom, Kwon Heo
Vol. 2, No. 1, pp. 18-22, Feb. 2006
Keywords: 3D Editing, 3D Synthesizing, 3D Object Reuse
Show / Hide AbstractThis paper proposes the framework of the scenario-based 3D image synthesizing system that allows common users who envision a scenario in their mind to realize it into the segments of cool animation. We focused on utilization of the existing motions to synthesize new motions for the objects. The framework is useful to build a 3D animation in game programming with a limited set of 3D objects. We also propose a practical algorithm to reuse and expand the objects. This algorithm is based on motion path modification rules. Both linear and nonlinear curve-fitting algorithms were applied to modify an animation by key frame interpolation and to make the motion appear realistic.
Vol. 2, No. 1, pp. 23-27, Feb. 2006
Keywords: Feature selection, Distributional Differences
Show / Hide AbstractThis paper presents a feature selection technique based on distributional differences for efficient machine learning. Initial training data consists of data including many features and a target value. We classified them into positive and negative data based on the target value. We then divided the range of the feature values into 10 intervals and calculated the distribution of the intervals in each positive and negative data. Then, we selected the features and the intervals of the features for which the distributional differences are over a certain threshold. Using the selected intervals and features, we could obtain the reduced training data. In the experiments, we will show that the reduced training data can reduce the training time of the neural network by about 40%, and we can obtain more profit on simulated stock trading using the trained functions as well.
Yixin Jing, Jinhyung Kim, Dongwon Jeong
Vol. 2, No. 1, pp. 28-33, Feb. 2006
Keywords: access control, Ubiquitous Computing, Task computing, Context-Awareness
Show / Hide AbstractThe initial research of Task Computing in the ubiquitous computing (UbiComp) environment revealed the need for access control of services. Context-awareness of service requests in ubiquitous computing necessitates a well-designed model to enable effective and adaptive invocation. However, nowadays little work is being undertaken on service access control under the UbiComp environment, which makes the exposed service suffer from the problem of ill-use. One of the research focuses is how to handle the access to the resources over the network. Policy-Based Access Control is an access control method. It adopts a security policy to evaluate requests for resources but has a lightweight combination of the resources. Motivated by the problem above, we propose a universal model and an algorithm to enhance service access control in UbiComp. We detail the architecture of the model and present the access control implementation.
Decision of Maximum Congestion Window Size for TCP Performance Improvement by Bandwidth and RTT Measurement in Wireless Multi-Hop NetworksIn Huh, Jae Yong Lee, Byung Chul Kim
Vol. 2, No. 1, pp. 34-38, Feb. 2006
Keywords: wireless multi-hop network, TCP, Congestion Window
Show / Hide AbstractIn the wireless network, TCP performs poorly because it was originally designed for wired networks and does not take into consideration wireless characteristics such as mobility, high-loss probability, and hidden-terminal problems. In particular, in the wireless multi-hop networks, a large congestion window increases the probability of contention and packet losses, and TCP performance is degraded severely as a result. So, it is necessary to limit the TCP congestion window size in order keep the probability of contention loss in the system to a minimum. In this paper, we propose a new scheme for determining the maximum congestion window size based on the measured bandwidth and Round-Trip-Time (RTT). Using ns-2 simulation, we show that the proposed scheme reduces the probability of packet contention and improves TCP performance.
Yuan Yang, Fu Zhen, Tae-Seok Lee, Myong-Soon Park
Vol. 2, No. 1, pp. 39-43, Feb. 2006
Keywords: Wireless Sensor Network, MAC Protocol, traffic aware, sleep/wake mechanism
Show / Hide AbstractIn this paper, we proposed TASL-MAC, a medium-access control (MAC) protocol for wireless sensor networks. In wireless sensor networks, sensor nodes are usually deployed in a special environment, are assigned with long-term work, and are supported by a limited battery. As such, reducing the energy consumption becomes the primary concern with regard to wireless sensor networks. At the same time, reducing the latency in multi-hop data transmission is also very important. In the existing research, sensor nodes are expected to be switched to the sleep mode in order to reduce energy consumption. However, the existing proposals tended to assign the sensors with a fixed Sleep/Listening schedule, which causes unnecessary idle listening problems and conspicuous transmission latency due to the diversity of the traffic-load in the network. TASL-MAC is designed to dynamically adjust the duty listening time based on traffic load. This protocol enables the node with a proper data transfer rate to satisfy the application¡¯s requirements. Meanwhile, it can lead to much greater power efficiency by prolonging the nodes¡¯ sleeping time when the traffic load of the network decreases. We evaluate our implementation of TASL-MAC in NS-2. The evaluation result indicates that our proposal could explicitly reduce packet delivery latency, and that it could also significantly prolong the lifetime of the entire network when traffic is low.
Ulziitugs Bud, JongTae Lim
Vol. 2, No. 1, pp. 44-47, Feb. 2006
Keywords: change detection, distance functions.
Show / Hide AbstractOne of the critical issues in a sensor network concerns the detection of changes in data streams. Recently presented change detection schemes primarily use a sliding window model to detect changes. In such a model, a distance function is used to compare two sliding windows. Therefore, the performance of the change detection scheme is greatly influenced by the distance function. With regard to sensor nodes, however, energy consumption constitutes a critical design concern because the change detection scheme is implemented in a sensor node, which is a small battery-powered device. In this paper, we present a comparative study of various distance functions in terms of execution time, energy consumption, and detecting accuracy through simulation of speech signal data. The simulation result demonstrates that the Euclidean distance function has the highest performance while consuming a low amount of power. We believe our work is the first attempt to undertake a comparative study of distance functions in terms of execution time, energy consumption, and accuracy detection.
Yoon-Su Jeong, Sang-Ho Lee
Vol. 2, No. 1, pp. 48-51, Feb. 2006
Keywords: cluster, Key Management Protocol, WSN
Show / Hide AbstractTo achieve security in wireless sensor networks (WSN), it is important to be able to encrypt messages sent among sensor nodes. We propose a new cryptographic key management protocol, which is based on the clustering scheme but does not depend on the probabilistic key. The protocol can increase the efficiency to manage keys since, before distributing the keys by bootstrap, the use of public keys shared among nodes can eliminate the processes to send or to receive keys among the sensors. Also, to find any compromised nodes safely on the network, it solves safety problems by applying the functions of a lightweight attack-detection mechanism.
Wook-Sun Shin, Doo-Heon Song, Chang-Hun Lee
Vol. 2, No. 1, pp. 52-57, Feb. 2006
Keywords: Vehicle Type classification, Road Lane Detection, Model fitting, Vanishing point, Machine Learning
Show / Hide AbstractOne of the important functions of an Intelligent Transportation System (ITS) is to classify vehicle types using a vision system. We propose a method using machine-learning algorithms for this classification problem with 3-D object model fitting. It is also necessary to detect road lanes from a fixed traffic surveillance camera in preparation for model fitting. We apply a background mask and line analysis algorithm based on statistical measures to Hough Transform (HT) in order to remove noise and false positive road lanes. The results show that this method is quite efficient in terms of quality.
Ji-Hye Bae, Hee-Kuk Kang, Yoon-Young Park, Jung-Ho Park
Vol. 2, No. 1, pp. 58-66, Feb. 2006
Keywords: Ubiquitous Computing, Monitoring System, Sensor Network
Show / Hide AbstractAccurate and efficient monitoring of dynamically changing environments is one of the most important requirements for ubiquitous network environments. Ubiquitous computing provides intelligent environments which are aware of spatial conditions and can provide timely and useful information to users or devices. Also, the growth of embedded systems and wireless communication technology has made it possible for sensor network environments to develop on a large scale and at low-cost. In this paper, we present the design and implementation of a monitoring system that collects, analyzes, and controls the status information of each sensor, following sensor data extracted from each sensor node. The monitoring system adopts Web technology for the implementation of a simple but efficient user interface that allows an operator to visualize any of the processes, elements, or related information in a convenient graphic form.