The QoS(Quality of Service) guarantee mechanism is one of critical issues in the wireless network. Real-time applications like VoIP(Voice over IP) in All-IP networks need smooth handoffs in order to minimize or eliminate datagram loss as a Mobile Host(MH) transitions between network links. In this paper, we design a new DB(Dynamic Buffering) mechanism for IPv6 by which an MH can request that the router on its current subnet buffers packets on its behalf while the MH completes registration procedures with the router of a new subnet. Performance results show that our proposed buffering scheme with a dynamic buffer space allocation is quite appropriate for mobile Internet, or the All-IP environment in terms of the datagram loss rate and average waiting time.

We describe 150-nm-thick collector InP-based double heterojunction bipolar transistors with two types of thin pseudomorphic bases. The emitter and collector layers are designed for high collector current operation. The collector current blocking is suppressed by the compositionally step-graded collector structure even at JC of over 500 kA/cm2 with practical breakdown characteristics. An HBT with a 20-nm-thick base achieves a high fT of 351 GHz at high JC of 667 kA/cm2, and a 30-nm-base HBT achieves a high value of 329 GHz for both fT and fmax at JC of 583 kA/cm2. An equivalent circuit analysis suggests that the extremely small carrier-transit-delay contributes to the ultrahigh fT.

An important area in visual communications is the restoration of image sequences degraded by channel and noise. Since a nonlinearity is commonly involved in image transmitting procedure, an adaptive nonlinear equalizer is required. In this paper we address this problem by proposing a 3D adaptive nonlinear filter, namely the 3D adaptive Volterra filter with an LMS type of adaptation algorithm. This adaptive filter is used for equalizing an unknown 2-D channel with some point-wise nonlinearity and restoring image sequences degraded by this channel. Prior to filtering, motion is estimated from the sequence and compensated for. For this purpose, a robust region-recursive Higher Order Statistics (HOS) based motion estimation method is employed. The overall combination is able to adequately remove undesired effects of communication channel and noise. The performance of this algorithm is examined using real image sequences demonstrated by experimental results.

We have classified parenchymal echo patterns of cirrhotic liver into four types, according to the size of hypo echoic nodular lesions. The NN (neural network) technique has been applied to the characterization of hepatic parenchymal diseases in ultrasonic B-scan texture. We employed a multilayer feedforward NN utilizing the back-propagation algorithm. We extracted 1616 pixels in the two-dimensional regions. However, when a large area is used, input data becomes large and much time is needed for diagnosis. In this report, we used DCT (discrete cosine transform) for the feature extraction of input data, and compression. As a result, DCT was found to be suitable for compressing ultrasonographic images.

In this letter, we show that Fan-Chen-Yeh's blind signature scheme and Chien-Jan-Tseng's partially blind signature scheme are vulnerable to the chosen-plaintext attack. We also show that both schemes can be modified so that the chosen-plaintext attack is impossible. But, still Chien-Jan-Tseng's partially blind signature scheme is vulnerable. It fails to satisfy the partial blindness property.

Recently, a new approach was presented to determine the high-frequency response of on-chip passives and interconnects. The method solves the electric scalar and magnetic vector potentials in a prescribed gauge. The latter one is included by introducing an additional independent scalar field, whose field equation needs to be solved. This additional field is a mathematical aid that allows for the construction of a gauge-conditioned, regular matrix representation of the curl-curl operator acting on edge elements. This paper reports on the convergence properties of the new method and shows the first results of this new calculation scheme for VLSI-based structures at high frequencies. The high-frequent behavior of the substrate current, the skin effect and current crowding is evaluated.

The encryption algorithm Camellia is a 128 bit block cipher proposed by NTT and Mitsubishi, Japan. Since the algebraic degree of the outputs after 3 rounds is greater than 128, designers estimate that it is impossible to attack Camellia by higher order differential. In this paper, we show a new higher order differential attack which controls the value of differential using proper fixed value of plaintext. As the result, we found that 6-round F-function can be attacked using 8th order differentials. The attack requires 217 chosen plaintexts and 222 F-function operations. Our computer simulation took about 2 seconds for the attack. If we take 2-R elimination algorithm, 7-round F-function will be attacked using 8th order differentials. This attack requires 219 chosen plaintexts and 264 F-function operations, which is less than exhaustive search for 128 bit key.

Randomly addressed polling was proposed as a multiple access control protocol for wireless local area networks (LANs). However, the protocol has difficulties in supporting real-time services such as voice transmission. We propose a reservation scheme and make it possible to support real-time services. The scheme is described in detail. Efficiency and average access delay are analyzed.

A number of mobile hosts might be densely staying in an area caused by traffic congestions. The greater part of the mobile hosts will require commonly useful data, such as traffic information, parking information and other driving related information in such environment. Simultaneous data transmission broadcasts using a common link are regarded as a suitable means to distribute this location-dependent information. However, there is no guarantee that mobile hosts can finish receiving the information completely within a limited time. In this paper, we propose a data retransmission method for communications between a base station and mobile hosts and a data recovery processing method for use between base stations. The data retransmission method called "TOA" (The Order of Arrival) schedules retransmission data specified in the first NACK request received after retransmission processing. We have proposed "Advanced" Join system in which a base station makes consolidated join requests to a multicast group on behalf of mobile hosts. Applying the TOA method to resending in the Advanced Join system, data-receiving efficiency is higher than with the simple Advanced Join system and the absolute number of completed mobile host data reception is higher. Using the TOA method, even with the base station disposition rate of 50% the number of completed reception is higher than with the Advanced Join system at 80%. The proposed reliable multicasting system to the DSRC-based ITS network can realize an efficient base station arrangement in the ITS network infrastructure and contribute to the deployment of a superior ITS.

Thin-film electroluminescent (TFEL) devices have been newly developed using Y2GeO5 oxide phosphor thin films prepared by r.f. magnetron sputtering. Multicolor emissions were observed in TFEL devices fabricated using various impurity-activated Y2GeO5 phosphor thin films. A high-luminance TFEL device was fabricated using a Y2GeO5:Mn thin film prepared with a Mn content of 2 at.% and postannealed at 1020: luminances of 414 and 3020 cd/m2 and luminous efficiencies of 6.7 and 0.93 lm/W for yellow emission when driven at 60 Hz and 1 kHz, respectively. Newly developed oxide Y2GeO5:Mn phosphors are very promising for use as the thin-film emitting layer of TFEL devices.

We obtained a relation between the characteristics of optical life and panel structural factors which is one of the important factors for panel design of Plasma Display Panel (PDP). We introduced the equation under the consideration that dominant factor determining the characteristics of optical life is luminance degradation of phosphors and that ion bombardment causes luminance degradation of phosphors. This equation contains the following four panel structural factors such as gap between electrodes, gas pressure, gas kinds, and voltage. Furthermore, we compared the equation with experimental values as a verification.

This paper proposes a multi-host RAID-5 architecture in which multiple hosts can access disk array via storage area network. In this configuration, parity inconsistency occurs when different hosts try to write to the same stripe simultaneously. Parity consistency can be ensured by the serialization of the writes to the same stripe with locking method. While conventional locking methods can be used, the performance is degraded in the case of large number of hosts. When multiple-reader single-writer file consistency semantic is used, most of the stripes are written exclusively by a single host, so parity inconsistency problem does not occur. By removing locking of those stripes which amounts to 95% in practical workloads, the performance becomes more scalable and 50% faster than using the conventional stripe locking methods.

The current-voltage characteristics of InP-based HBTs with InAlAs-InP composite emitters have been measured as a function of the thickness of the InP layer in the emitter. As the thickness varies, characteristics such as the gain and the ideality factor vary qualitatively as expected from the changes in position of the InAlAs barrier in the emitter. Quantitatively, however, the variations indicate that the interfaces vary systematically with InP thickness, becoming more abrupt for emitters with thicker InP layers.

InP-based high electron mobility transistors (HEMTs) with gate lengths reduced to 30 nm were fabricated and characterized, and the effect of the gate recess on the high-frequency characteristics was studied. The cutoff frequency, which is regarded as a function of the gate length and the average carrier velocity in a first-order approximation, depends on the size of the gate recess when the gate length becomes short. The size of the gate recess is optimized by taking the feed-back capacitance and the parasitic resistance into account. For HEMTs having the gate recess with an InP surface, an appropriate widening of the gate recess gives a record cutoff frequency of 368 GHz for the 30-nm-gate HEMTs with a lattice-matched channel.

We introduce a refined definition of semantic security. The new definition is valid against not only chosen-plaintext attacks but also chosen-ciphertext attacks whereas the original one is defined against only chosen-plaintext attacks. We show that semantic security formalized by the new definition is equivalent to indistinguishability, due to Goldwasser and Micali for each of chosen-plaintext attacks, non-adaptive chosen-ciphertext attack, and adaptive chosen-ciphertext attack.

At Eurocrypt'98, Okamoto and Uchiyama presented a new trap-door (one-way) function based on factoring, while Fujisaki and Okamoto, at CRYPTO'99, showed a generic conversion from just one-way encryption to chosen-cipher secure encryption in the random oracle model. This paper shows that the result of combining both schemes is well harmonized (rather than an arbitrary combination) and, in the sense of exact security, boosts the level of security more than would be expected from [6]--The security of the scheme yielded by the combination is tightly reduced from factoring. This paper also gives a rigorous description of the new scheme, because this type of encryption may suffer serious damage if poorly implemented. The proposed scheme is at least as efficient as any other chosen-cipher secure asymmetric encryption scheme such as [2],[4],[13].

This paper newly formalizes some notions of security for probabilistic public-key encryption schemes. The framework for these notions was originally presented in the work by Bellare et al., in which they consider non-malleability and indistinguishability under chosen-plaintext attack, non-adaptive chosen-ciphertext attack and adaptive chosen-ciphertext attack. This paper extends the results of Bellare et al. by introducing two goals, equivalence undecidability and non-verifiability under the above three attack models. Such goals are sometimes required in electronic voting and bids systems. It is shown that equivalence undecidability, non-verifiability and indistinguishability are all equivalent under the three attack models.

A novel fabrication process and materials of LC layers have been developed for three layer LCDs. It is based on LC/resist composite that can be applied to patterning LC layers with high resolution by conventional photolithography processes. Using this process, we fabricated a 2" matrix panel of three GH-LC layers stacked on a substrate for the fist time.

This paper presents a simple and generic conversion from a public-key encryption scheme that is indistinguishable against chosen-plaintext attacks into a public-key encryption scheme that is indistinguishable against adaptive chosen-ciphertext attacks in the random oracle model. The scheme obtained by the conversion is as efficient as the original encryption scheme and the security reduction is very tight in the exact security manner.

For the realization of low-voltage full-color FEDs, requirements for phosphor for the FED are proposed. Especially, the influence of released gases or substances from phosphors on the field emission within the FED was made clear. It was clarified that the analysis of F-N plots of the V-I curve of field emission characteristics was helpful to know the interaction of field emission and phosphors. In the experiment, we first obtained the depth from the phosphor surface of the low voltage electron excitation in case of ZnGa2O4, where the region available for cathodoluminescence at the anode voltage of 400 V is about 63 nm deep from the surface. The characteristic of the 12.4 cm-320(trio)240 pixels low-voltage full-color FED is reported. The luminance of 154 cd/m2 was attained at the anode voltage of 400 V and the duty factor of 1/241. Supported by the high potential of the FED as a flat panel, each problem shall be steadily solved to secure the firm stand as a new full color flat display in new applications.