This paper investigates the stochastic property of the packet destinations and proposes an address generation algorithm which is applicable for describing various Internet access patterns. We assume that a stochastic process of Internet access satisfies the stationary condition and derive the fundamental structure of the address generation algorithm. Pseudo IP-address sequence generated from our algorithm gives dependable cache performance and reproduces the results obtained from trace-driven simulation. The proposed algorithm is applicable not only to the destination IP address but also to the destination URLs of packets, and is useful for simulation studies of Internet performance, Web caching, DNS, and so on.

The diverse broadcast means that will be available in the future will cause an increased demand for programs. When the input of the posture of an agent is used to manipulate a virtual computer graphics actor, it is better if the system does not require a special studio and devices. In the present paper, we propose a way to extract images from a single picture based on estimates of blooming. This is done using a partial auto-correlation analysis that carries out backward and forward predictions simultaneously. And, we divide targets into the stratified depth from a single image. An experiment was conducted using a picture taken with a digital camera, and satisfactory results were obtained.

It has been reported that IP packet traffic exhibits the self-similar nature and causes the degradation of network performance. Therefore it is crucial for the appropriate buffer design of routers and switches to predict the queueing behavior with self-similar input. It is well known that the fitting methods based on the second-order statistics of counts for the arrival process are not sufficient for predicting the performance of the queueing system with self-similar input. However recent studies have revealed that the loss probability of finite queuing system can be well approximated by the Markovian input models. This paper studies the time-scale impact on the loss probability of MMPP/D/1/K system where the MMPP is generated so as to match the variance of the self-similar process over specified time-scales. We investigate the loss probability in terms of system size, Hurst parameters and time-scales. We also compare the loss probability of resulting MMPP/D/1/K with simulation. Numerical results show that the loss probability of MMPP/D/1/K are not significantly affected by time-scale and that the loss probability is well approximated with resulting MMPP/D/1/K.

This paper presents a new network architecture called LINA that provides node mobility. The basic concept of LINA is separation of the node identifier and the interface locator. Although there are several protocols based on such a concept, they do not address issues that arise when dealing with an entire network architecture. LINA is a holistic architecture covering the network layer to the application layer in order to support node mobility. Overhead incurred by separation of the node identifier and the interface locator is minimized in LINA by introducing the embedded addressing model. This paper also presents a new protocol called LIN6 that supports IPv6 mobility. LIN6 is an application of LINA to IPv6 and is fully compatible with IPv6. It has several advantages in comparison to Mobile IPv6, e.g. less protocol overhead. Our prototype implementation of LIN6 shows minimal overhead compared to a conventional IPv6 implementation.

Since each ATM virtual path (VP) contains bundles of virtual channels (VCs), a VP layer network can serve as a server layer and each VC layer network can be a client layer. Therefore the effective VC service provisioning depends completely on the reliability of the VP layer network. We propose the ATM virtual path (VP) management framework with dynamic routing and rerouting schemes in a hierarchical transport network. The routing algorithm aims to provide the globally optimal route in a hierarchical network environment from the perspectives of maximization of network resource utilization and satisfaction of the end user's QoS requirement. The rerouting algorithm guarantees network survivability in the event of network faults or performance degradations. We also propose the implementation model of the ATM virtual path network management system (VP-NMS). Lastly, we evaluate the routing and rerouting performance for a real network, the High Speed Information Network (HSIN) of Korea Telecom.

The unidirectional transmission links such as broadcast satellite links and cable links are strongly demanding type of link to provide high bandwidth and ubiquitous Internet connectivity with lower cost. In order to provide an internet connectivity, the UDLs, unidirectional links, should be available for the IP service. However, since the current Internet routing and upper layer protocols assume the bi-directional link, the UDLs have been considered as unavailable links for the IP service. This paper proposes an architecture and a mechanism for the IP service over the UDL. The proposed system emulates the bi-directional connectivity between all nodes on the UDL, in order to use the dynamic routing protocol, the TCP/IP protocol, on the UDL system. Receiver uses a link layer tunneling mechanism to forward the IP datagrams to the Feed over an IP cloud, that is not directly connected to the UDL. This proposed architecture enables the dynamic routing capability for UDLs, as well as user applications, without any software modification.

Layering architecture of the Internet Protocol provides independent processing for each layer by concealing state information from each layer. Application Program Interface (API) is based on the idea of layering model. However, the idea disturbs efficient processing of applications requiring adaptation to network environment, such as context-aware applications in mobile computing. To address this need, this paper proposes MIBsocket designed as an integrated control and management system for general network information. Any variable information related to network is shared between each applications and operating system. MIBsocket detects and informs changes in network resources to applications. MIBsocket functions such as Get, Set, and Trap used in the application adapts dynamically to any environments. MIBsocket provides portability and facility for applications: it only requires a few modification to the operating system and its API has the same programmable interfaces as usual API's. MIBsocket does not interfere the current layering architecture, but it achieves remarkable improvement on the current model. We have measured costs of MIBsocket, and applied MIBsocket to the application named interface switching system which enables a mobile host to connect to the Internet anytime by switching interface depending on network environment. As a result, the costs of MIBsocket was found acceptable. The application shows that MIBsocket is useful for movement detection and reconfiguration of network resources in the mobile computing.

In this paper we describe a multicast routing algorithm, which builds upon mobile multicast agents of an ad-hoc network. Mobile multicast agents (MMAs) form a virtual backbone of an ad-hoc network and they provide multicast tree discovery, multicast tree maintenance and datagram delivery. First, we construct a cluster-spine hierarchy structure for an ad-hoc network. Second, we propose a multicast routing algorithm, which is inspired by Ad-hoc On-Demand Distance Vector (AODV) routing protocol. The results show that the MMA multicast algorithm can simplify the multicast tree discovery, reduce control overhead of the network, and increase the total network throughput, in comparison with general AODV multicast operation. We also overcome the deficiency of CBRP multicast routing, which places much burden on cluster heads.

As a method of analyzing the wave scattering from a finite periodic surface, this paper introduces a periodic approach. The approach first considers the wave diffraction by a periodic surface that is a superposition of surface profiles generated by displacing the finite periodic surface by every integer multiple of the period . It is pointed out that the Floquet solution for such a periodic case becomes an integral representation of the scattered field from the finite periodic surface when the period goes to infinity. A mathematical relation estimating the scattering amplitude for the finite periodic surface from the diffraction amplitude for the periodic surface is proposed. From some numerical examples, it is concluded that the scattering cross section for the finite periodic surface can be well estimated from the diffraction amplitude for a sufficiently large .

A mobile ad hoc network (MANET) is a characterized by multi-hop wireless links, absence of any cellular infrastructure, and frequent host mobility. Existing MANET routing protocols are divided into location-aware and non-location-aware routing protocols. In a location-aware routing protocol, location information can be exploited to facilitate routing. Our protocol, namely multi-eye spiral-hopping (MESH) routing protocol, is a location-aware routing protocol. Most promising routing protocols are constructed by the route-discovery, route-reply, and route-maintenance phases. Our MESH protocol utilizes the location-information to confine the blind-flooding region in the route-discovery phase, minimize route-reply packets in the route-reply phase, and promote the routing robustness in the route-maintenance phase. Two major contributions of this paper are introduced: (1) a multi-eye scheme is presented to confine route-discovery region for reducing redundant packets, and (2) a special multi-path scheme, called as spiral-hopping scheme, is introduced to provide on-line route-recovery capability. Extensive simulations are conducted to evaluate the protocol.

Making up a microwave simulator is tried, which has an analysis method based on the finite-element method as a solver and commercial tools as a pre- and post-processor of a graphical user interface. The platform of this simulator is Windows, but, since the codes and configuration files to be created are common on Windows, Unix, and Linux, the simulator running on any platform may be made up at the same time, except a document on which all the commands of the simulator are embedded and executable. Using the simulator, the transmission properties of a 2- and 3-D waveguide discontinuity in a microwave circuit and eigenmodes of a 2- and 3-D waveguide are analyzed, and the computed results are presented in graphs of S parameters and plots of the electric field distribution.

Emerging multimedia technologies introduce the prevalent multicast transmission, and the multicast tree is determined using the time-invariant network parameters. This paper addresses the time-varying multicast tree problem and presents path selection heuristics for multicast routing to determine an alternative path for real-time applications. A network is partitioned into the optimal region, the disjoint region, and the edge cutset if a branch of the multicast tree meets the un-guaranteed QoS condition. The path selection heuristics operate during the multicast session phase to efficiently select an alternative routing path containing an edge in the edge cutset to connect the multicast tree again. The source-based heuristics PS-SPT finds the path for minimal source-to-destination delay and the sharing-based heuristics PS-DDMC for minimal total cost. These path selection heuristics can efficiently provide solutions to keep the multicast transmission reliable. Simulation results also show that the proposed heuristics can provide effective good solutions for real-time multicast transmission. PS-SPT can select a path with optimal source-to-destination delay and PS-DDMC can select a path with optimal total cost.

It is very difficult to obtain a linearizing feedback and a coordinate transformation map, even though the system is feedback linearizable. It is known that finding a desired transformation map and feedback is equivalent to finding an integrating factor for an annihilating one-form. In this paper we develop a numerical algorithm for an integrating factor involving a set of partial differential equations and corresponding zero-form using the C.I.R method. We employ a tensor product splines as an interpolation method to data which are resulted from the numerical algorithm in order to obtain an approximate integrating factor and a zero-form in closed forms. Next, we obtain a coordinate transformation map using the approximate integrating factor and zero-form. Finally, we construct a stabilizing controller based on a linearized system with the approximate coordinate transformation.

Precise and quick multi-beam forming including null control will be one of the key technologies for the future satellite communication systems utilizing SDMA (Space Division Multiple Access) and DOA (Direction of Arrival) estimation. In order to realize the precise multi-beam forming, calibration procedure is indispensable since there are several unavoidable factors that degrade the multi-beam patterns of the array. Particularly amplitude and phase imbalance between RF circuits needs to be calibrated frequently and quickly when the array system exists in changeable environment since the imbalance easily occurs due to thermal characteristics of each RF circuit. This paper proposes a simple and high-speed remote calibration scheme compensating for amplitude and phase imbalance among RF circuits of a transmitting adaptive array antenna onboard satellite. This calibration is conducted at a remote station such as a gateway station on the ground in the satellite communication system, by utilizing the received signal including the temporally multiplexed orthogonal codes transmitted from the array antenna onboard satellite. Since the calibration factors for all the antenna elements can be simultaneously obtained by the parallel digital signal processing, calibration time can be drastically reduced. The accuracy of this calibration is estimated by simulation. Simulation results show that the amplitude imbalance among RF circuits can be suppressed within the range from -0.5 dB to +0.25 dB for the initial imbalance ranging from -2 dB to +3.5 dB, phase imbalance can be suppressed within the range of -3 deg. to +3 deg. for the initial imbalance ranging from -120 or +180 deg. by this method. The amplitude and phase deviations among the elements can be suppressed within 0.36 dB and 2.5 degrees, respectively, in 80% of probability. Simulation results also show that this calibration method is valid under the relatively bad carrier-to-noise conditions such as -10 dB at the receiver. Good improvement of the multi-beam patterns by this calibration is shown under the low carrier-to-noise ratio condition.

EMI coupling paths in an electronic controller are investigated experimentally. Common-mode current measurements on the attached cable are used for diagnosing changes made to the EMI coupling path. Experiments that include shielding various portions of the PCB, and re-routing high-speed traces are conducted to characterize the coupling path. A means of identifying and characterizing EMI coupling paths in functioning hardware, and relating them to design features, is demonstrated.

This paper describes a biometric-based key generation method and its application to a secure communication system. In the proposed method, a personal key which is unique to each user is generated by extracting his/her biometric information. Using the generated personal key, a secure communication system which has the functions of confidentiality and user authentication is realized. As an example of the proposed method, we introduce a personal key generation method based on one's handwriting, and a secure telewriting system which enables the encryption of handwriting information as well as the authentication of a writer. Some simulation results indicate the possibility of realizing the above functions by using a writer's personal key.

In a mobile computing environment, the characteristics of wireless communication and host mobility are important considerations in providing an efficient payment service. Currently, most payment systems were not intended for use in a mobile environment, and as such they inherently possess some inefficient properties. In this paper, we propose a new micropayment system (AMPS), designed for use in a mobile computing environment. AMPS reduces the computational load of mobile hosts by directing operations normally performed by the client to the static portion of the network. With AMPS, a client's request for goods goes to a TTP server, called the AMPS server, using only one message. The client can also be disconnected while the AMPS server deals with the merchant, reducing communication costs and power consumption. User privacy is protected by hiding the details of the payment to the AMPS server. The AMPS server can also provide client anonymity to merchants. Another advantage of AMPS is the provision of transaction atomicity by checking goods and money before forwarding to clients or merchants, and preserving all necessary information for any possible future disputes.

In this paper, we propose an approach to test pattern generation for Speed-Independent (SI) asynchronous control circuits. Test patterns are generated based on a specified sequence, which is derived from the specification of a target circuit in the form of a Signal Transition Graph (STG). Since the sequence represents the behavior of a circuit only with stable states, the state space of the circuit can be represented as reduced one. A product machine, which consists of a fault-free circuit and a faulty circuit, is constructed and then the specified sequence is applied sequentially to the product machine. A fault is detected when the product machine produces inconsistency, i.e., output values of a fault-free circuit and a faulty circuit are different, and the sequentially applied part of the sequence becomes a test pattern to detect the fault. We also propose a test generation method using an undetectable fault identification as well as the specified sequence. Since the reduced state space is a subset of that of a gate level implementation, test patterns based on a specification cannot detect some faults. The proposed method identifies those faults with a circuit topology in advance. BDD is used to implement the proposed methods efficiently, since the proposed methods have a lot of state sets and set operations. Experimental results show that the test generation using a specification achieves high fault coverage over single stuck-at fault model for several synthesized SI circuits. The proposed test generation using a circuit topology as well as a specification decreases execution time for test generation with negligible cost retaining high fault coverage.

An electroretinogram (ERG) represents the global responses of the retina to a visual stimulus and shows accumulated responses of each layer of the retina relative to the signal processing mechanisms occurring within the retina. Thus, investigating the reaction types of each ERG wave provides information required for diagnosis and for identifying the signal processing mechanisms in the retina. In this study, an ERG signal is generated by simulating the volume conductor field response for each retina layer, which are then summed algebraically. The retina model used for the simulation is Shah's Computer Retina model, which is the most reliable model developed so far. When the generated ERG is compared with a typical clinical ERG it exhibits a close similarity. Based on changing the parameters of the ERG model, a diagnostic investigation is performed with a variation in the ERG waveform.

A great deal of effort has been concentrated on the longitudinal control for the collision avoidance of moving vehicles. In an emergency as well as in a normal situation, however, the steering control can be a very effective alternative as observed in the practice of manual evasive driving. In the reported methods of steering control, it is found that the dynamic motions of the neighboring vehicles are often ignored, which may result in some danger of 2nd collision. Therefore, it is necessary to assess the surrounding traffic situation to prevent 2nd collision that can occur just after escaping from the 1st collision situation. In this paper, we tackle the collision avoidance problem when steering actuation control is allowed in consideration of the dynamic motion of the neighboring vehicles. Specifically, a hierarchical control scheme is suggested as a feasible solution, and the proposed system is verified via simulation using a software simulator called DevACAS (DEVeolper of Active Collision Avoidance System), which we have developed.