We consider the problem of computing the optimal swap edges of a shortest-path tree. This problem arises in designing systems that offer point-of-failure shortest-path rerouting service in presence of a single link failure: if the shortest path is not affected by the failed link, then the message will be delivered through that path; otherwise, the system will guarantee that, when the message reaches the node where the failure has occurred, the message will then be re-routed through the shortest detour to its destination. There exist highly efficient serial solutions for the problem, but unfortunately because of the structures they use, there is no known (nor foreseeable) efficient distributed implementation for them. A distributed protocol exists only for finding swap edges, not necessarily optimal ones. We present two simple and efficient distributed algorithms for computing the optimal swap edges of a shortest-path tree. One algorithm uses messages containing a constant amount of information, while the other is tailored for systems that allow long messages. The amount of data transferred by the protocols is the same and depends on the structure of the shortest-path spanning-tree; it is no more, and sometimes significantly less, than the cost of constructing the shortest-path tree.

This paper investigates zero pronouns in Korean, especially focusing on the center transitions of adjacent utterances under the framework of Centering Theory. Four types of nominal entity (Epair, Einter, Eintra, and Enon) from Centering Theory are defined with the concept of inter-, intra-, and pairwise salience. For each entity type, a case study of zero phenomena is performed through analyzing corpus and building a pronominalization model. This study shows that the zero phenomena of entities which have been neglected in previous Centering works are explained via the center transition of the second previous utterance, and provides valuable results for pronominalization of such entities, such as p2-trans rule. We improve the accuracy of pronominalization model by optimal feature selection and show that our accuracy outperforms the accuracy of previous works.

We propose a method of dimensioning and managing the bandwidth of a link on which flows with heterogeneous access-link bandwidths are aggregated. We use a processor-sharing queue model to develop a formula approximating the mean TCP file-transfer time of flows on an access link in such a situation. This only requires the bandwidth of the access link carrying the flows on which we are focusing and the bandwidth and utilization of the aggregation link, each of which is easy to set or measure. We then extend the approximation to handle various factors affecting actual TCP behavior, such as the round-trip time and restrictions other than the access-link bandwidth and the congestion of the aggregation link. To do this, we define the virtual access-link bandwidth as the file-transfer speed of a flow when the utilization of the aggregation link is negligibly small. We apply the virtual access-link bandwidth in our approximation to estimate the TCP performance of a flow with increasing utilization of the aggregation link. This method of estimation is used as the basis for a method of dimensioning the bandwidth of a link such that the TCP performance is maintained, and for a method of managing the bandwidth by comparing the measured link utilization with an estimated threshold indicating degradation of the TCP performance. The accuracy of the estimates produced by our method is estimated through both computer simulation and actual measurement.

We propose an adaptive plastic-landmine visualizing radar system employing a complex-valued self-organizing map (CSOM) dealing with a feature vector that focuses on variance of spatial- and frequency-domain inner products (V-CSOM) in combination with aperture synthesis. The dimension of the new feature vector is greatly reduced in comparison with that of our previous texture feature-vector CSOM (T-CSOM). In experiments, we first examine the effect of aperture synthesis on the complex-amplitude texture in space and frequency domains. We also compare the calculation cost and the visualization performance of V- and T-CSOMs. Then we discuss merits and drawbacks of the two types of CSOMs with/without the aperture synthesis in the adaptive plastic-landmine visualization task. The V-CSOM with aperture synthesis is found promising to realize a useful plastic-landmine detection system.

The Oblivious Transfer (OT), introduced by Rabin in 1981, has become an important and fundamental cryptography technique. An OT protocol should have two important characteristics: the sender's privacy and the chooser's privacy. The sender is a party who will deliver a secret to the chooser. The chooser is another party who acts as receiver to learn some information about the input from the sender. The chooser learns of certain information concerning the sender's input while the sender is not allowed to know what the chooser has learned. Moreover, the chooser cannot acquire any messages that he/she did not choose. Naor and Pinkas have recently proposed an efficient oblivious transfer protocol (EOT) that implementes 1-out-of-n protocol, but this EOT has a flaw: it cannot withstand "the same message attack." In this paper, we will improve Naor and Pinkas EOT and make it resistant to "the same message attack."

A fully Internet-connected business environment is subject to frequent changes. To ordinary customers, online shopping under such a dynamic environment can be frustrating. We propose a new E-commerce service called the CIGMA to assist online customers under such an environment. The CIGMA provides catalog comparison and purchase mediation services over multiple shopping sites for ordinary online customers. The service is based on up-to-date information by reflecting the frequent changes in catalog information instantaneously. It also matches the desire of online customers for fast response. This paper describes the CIGMA along with its architecture and the implementation of a working prototype.

In order to judge the goodness of zero correlation zone sequence sets, a new concept, called ZCZ characteristic, is proposed. Then by defining a sequence operation, i.e. correlation product, and establishing its basic properties, a new approach to construct sets of sequences with a large zero correlation zone is presented.

Based on hybrid system theory, we propose a modeling and control approach for a multi-contact planar manipulation system, whereby a dexterous manipulation task is formulated as a mixed logic dynamical (MLD) model. The MLD model provides the possibility of carrying out the selection of modes, the timing for mode switching, and the determination of the continuous control input simultaneously in a systematical way. Model predictive control (MPC) is adopted for the synthesis of the dexterous hand manipulation system. The solution of the MPC can be found by using mixed integer quadric programming (MIQP) algorithm, and corresponds to the optimal motion of the hand manipulation. The validation of the proposed approach is shown by some simulation results.

In this paper the spectral density of the additive jitter noise in continuous time (CT) Delta-Sigma modulators (DSM) is derived analytically. Making use of the analytic results, extracted in this paper, a novel method for elimination of the damaging effects of the clock jitter in continuous time Delta-Sigma modulators is proposed. In this method instead of the conventional waveforms used in the feedback path of CT DSM's such as the non return to-zero, the return to-zero, and the half delay return to-zero, an impulse waveform is employed.

Prediction of actual symbol probability is crucial for statistical data compression that uses arithmetic coder. Krichevsky-Trofimov (KT) estimator has been a standard predictor and applied in CTW or FWCTW methods. However, KT-estimator performs poorly when non occurring symbols appear. To rectify this we proposed a zero-redundancy estimator, especially with a finite window(Rashid and Kawabata, ISIT2003) for non stationary source. In this paper, we analyze the zero-redundancy estimators in the case of Markovian source and give an asymptotic evaluation of the redundancy. We show that one of the estimators has the per symbol redundancy given by one half of the dimension of positive parameters divided by the window size when the window size is large.

Though there are intensive researches on off-line electronic cash (e-cash), the current computer network infrastructure sufficiently accepts on-line e-cash. The on-line means that the payment protocol involves with the bank, and the off-line means no involvement. For customers' privacy, the e-cash system should satisfy unlinkability, i.e., any pair of payments is unlinkable w.r.t. the sameness of the payer. In addition, for the convenience, exact payments, i.e., the payments with arbitrary amounts, should be also able to performed. In an existing off-line system with unlinkable exact payments, the customers need massive computations. On the other hand, an existing on-line system does not satisfy the efficiency and the perfect unlinkability simultaneously. This paper proposes an on-line system, where the efficiency and the perfect unlinkability are achieved simultaneously.

Overlay multicast schemes for Mobile Ad hoc Networks (MANET) [1] have been proposed to remove non group members' dependency for multicast forwarding. However, since all packets are relayed from one group member to other group member in a form of unicast packet, they sometimes cause a lot of packets' collision and low resource utilization particularly where group members densely locate. In this paper, we propose a new forwarding scheme, DESIRE (Density awarE heterogeneouS overlay multIcast foRwarding schemE in MANET), for overlay multicast in MANET. DESIRE is significantly different from previous overlay multicast schemes in that it creates separate data forwarding path over overlay DDT (Data Delivery Tree) depending on density of group members. In dense environment, a zone is constructed and a scoped flooding is applied within it. On the other hand, in sparse environment, data dissemination is accomplished in a form of unicast packet similar to previous overlay multicast. By adapting scoped flooding in dense environment, it can reduce a lot of packets' collision and balance battery consumption by making use of mobile node's broadcast capability entirely. Also, in sparse environment, DESIRE can cope with network mobility very well since overlay DDT can remain static regardless of changes in physical topology. Such distinct advantages are evaluated by simulation. Generally, better performance is shown with large group members than small group members.

ERS-1/2 wind scatterometers (WSC) data sets may contain cells in which two, instead of three, measurements are available. These data sets are called incomplete. Operational inversion procedures discard such data sets and therefore no wind field is estimated. This is very limiting in semi-closed seas such as the Mediterranean Sea. In this paper we propose a new inversion procedure capable to retrieving near surface wind fields from incomplete data sets. This procedure is an enhancement of an algorithm already proposed and tested by the authors. A set of comprehensive experiments are presented and discussed. It is shown that the inversion procedure gets to remarkable results even in presence of a large number of doublets.

Many routing protocols have been proposed for mobile ad hoc networks. Among these protocols, the on-demand routing protocols are very attractive because they have low routing overhead. However, few of the existing on-demand routing protocols have considered the link heterogeneity, such as the different communication rate, different Packet Error Ratio (PER). As a result, the routes tend to have the shortest hop count and contain weak links, which usually provide low performance and are susceptible to breaks in the presence of mobility. In this paper, we analyze the existing on-demand routing protocols and propose a Link Heterogeneity Aware On-demand Routing (LHAOR) protocol, where the link quality and mobility are considered. Specifically, the Local Update (LU) is proposed and the link metric is inversely related with the Received Signal Strength Indicator (RSSI). By using the LU method and RSSI information, the routes adapt to the topology variation and link quality changes, and reach the local optimum quickly, which contains strong links and has a small metric. Simulation and experiment results show that our LHAOR protocol achieves much higher performance than the classical on-demand routing protocols.

We initiated development of our own data processing software for laser microscope data with C# language. This software is provided with volume calculation function of a target portion, based on a new calculation algorithm that can precisely handle the volume calculation of the portion located on a tilted surface or on a distorted surface. In this paper, this algorithm and some exemplary results obtained thereby, as well as some further development aims, are briefly described.

The effect of intermediate frequency magnetic fields or, very-low-frequency magnetic fields (VLFMF) on living biological cells was investigated using a highly sensitive mutagenesis assay method. A bacterial gene expression system for mutation repair (umu system) was used for the sensitive evaluation of damage in DNA molecules. Salmonella typhimurium TA1535 (pSK1002) were exposed to VLFMF (20 kHz and 600 µT) in a specially designed magnetic field loading chamber. The experiment results showed the possibility of applying the umu assay for sensitive and effective evaluation of damage in DNA molecules. No effects from exposure to 20 kHz and 600 µT magnetic fields in terms of damage in DNA molecules were observed.

Future wireless/mobile system is expected to have heterogeneous wireless overlay networks for ubiquitous multimedia communication. In a such network environment, mobile users are likely to try to get attached to higher bandwidth network as bandwidth-hungry multimedia applications are increasing. However, the users have to perform vertical handoff to lower bandwidth network, as high bandwidth network become unavailable due to various reasons (such as its limited coverage, network congestion, etc.). In this paper, we discuss the problem of vertical handoff from a user's perspective. For this purpose, we formulate user satisfaction as a function of bandwidth utility and handoff latency. Then, we investigate the effect of call holding time, user movement probability, etc. on the satisfaction that a user derives from the use of network service for multimedia applications. In addition, based on the evaluation, we present an algorithm for selecting a wireless network, which maximizes the effective user satisfaction.

The present paper introduces a new construction of a class of binary sequence set having a zero-correlation zone (hereafter binary zcz sequence set). The cross-correlation function and the side-lobe of the auto-correlation function of the proposed sequence set is zero for the phase shifts within the zero-correlation zone. The present paper shows that such a construction generates a binary zcz sequence set by using a primitive linear recursion over GF(2), the finite field of integers modulo 2.

A fiber-optic broadband signal distribution link based on a millimeter-wave self-heterodyne transmission/optical remote heterodyne detection technique was developed. To avoid having to use expensive optical and millimeter-wave devices to construct a frequency-stable fiber-optic millimeter-signal transmission system, a millimeter-wave self-heterodyne transmission technique was used, in which transmitted signals were generated by an optical remote heterodyne detection scheme. Theoretical discussion and experiments demonstrated that it is possible to construct an inexpensive millimeter-wave signal distribution link without the complexity or difficulties of a conventional link structure because applying the principle of the millimeter-wave self-heterodyne transmission technique enables the use of an unstable millimeter-wave carrier generated by heterodyning of two independently operating lasers. It was experimentally demonstrated that the proposed fiber-optic millimeter-wave link could successfully achieve bit-error-free transmission of a 156-Mb/s QPSK-formatted signal over a 10-km fiber link and a 5-m pseudo-air link.

Various types of radars have been developed and used until now--such as Pulse, FM-CW, and Spread Spectrum. Additionally, we have proposed another type of radar which measures distances by using standing wave. We have named it as "Standing Wave Radar." It has a shorter minimum detectable range and higher accuracy compared to other types. However, the radar can not measure distances down to zero meters like other types of radars. Minimum detectable range of the standing wave radar depends on a usable frequency range. A wider frequency range is required if we need to measure shorter distances. Consequently, we propose a new method for measuring distances down to zero meters without expanding the frequency range. We use an analytic signal, which is a complex sinusoidal signal. The signal is obtained by observing the standing wave with multiple detectors. We calculate distances by Fourier transform of the analytic signal. Moreover, we verify the validity of our method by simulations based on numerical calculation. The results show that it is possible to measure distances down to zero meters. In our method, measurement errors are caused by deviations of position and gain of the detectors. They are around 10cm at the largest if the gain deviations are up to 1% and the position deviations are up to 6% of the spacing between the detectors. Prevalent radars still have a common defect that they can not measure distances from zero to several meters. We expect that the defect will be eliminated by putting our method into practical use.