In this paper, a new family S(r) of 2n binary sequences of period 2n-1 is proposed, where n ≡ 2 mod 4 and gcd(r, 2n/2-1)=1. The presented family takes 4-valued out-of-phase auto- and cross-correlation values -1, 2n/2-1, and 2n/2+1-1, and its correlation distribution is determined. For r=2(n-2)/4-1, each sequence in S(r), except the unique ideal autocorrelation sequence in the family, is proved to have a large linear span n2n/2-2, whilst the linear span of the latter is n2(n-2)/4-1.

Recently, Yoon et al. exhibited the vulnerability of the smart-card-equipped password based authentication protocol proposed by Chien et al. to the Denning-Sacco attack. Furthermore, they also pointed out that the protocol does not provide the perfect forward secrecy. Accordingly, they presented an enhanced protocol to strengthen the security. This letter, however, demonstrates an interleaving attack on the Yoon et al.'s improved protocol and also discusses how to defend the protocol from the attack presented here.

In this paper, a chromatic adaptation model (CAM) based on the dependence on LMS cone responses of the human visual system (HVS) is proposed for TV and PC monitors under a variety of viewing conditions. We derived the proposed CAM based on Breneman's corresponding color data. The results of the experiments were carried out to assess the proposed model performance in terms of color fidelity by comparing complex images on a LCD monitor. We confirmed that the proposed model performed better to predict corresponding colors under various viewing conditions. Therefore, the reproduced colors, which are viewed in real surround viewing conditions, are perceived the same as original object colors, when the proposed CAM was applied to color display devices such as CRT, LCD, and PDP.

In this paper, ultra-wideband (UWB) multiple access systems are introduced by using direct-sequence (DS) and hybrid direct-sequence time-hopping (DS/TH) code division multiple access (CDMA) that use arbitrary chip-duty of the spreading sequences. The bit error probabilities are presented. First of all, the variances of the multiple access interference are developed by investigating the collision properties of the signals. Afterward, various approximations are applied. The standard Gaussian approximation (SGA) for the DS system is shown to become extremely optimistic as the chip-duty becomes low. Though the hybrid system performs better, the SGA still remains optimistic. To obtain accurate results, Holtzman's simplified improved Gaussian approximation (SIGA) and Morrow and Lehnert's improved Gaussian approximation (IGA) are used. A shortcoming of the SIGA is rediscovered that renders it unusable for low-duty DS systems, especially, at high signal-to-noise ratio. However, for the hybrid system, the SIGA works as an excellent tool. The IGA is used to get accurate results for the low-duty DS systems. It is shown that lowering of chip-duty by keeping chip rate and chip length unchanged improves performance for asynchronous DS and both asynchronous and synchronous hybrid systems. However, under the same processing gain, a high-duty system performs better than a low-duty system. Performance of synchronous DS system remains independent of chip-duty.

This paper proposes a simple and efficient method to numerically obtain the mapping degree deg(f, 0, B) of a C1 map f : Rn → Rn at a regular value 0 relative to a bounded open subset B ⊂ Rn. For practical application, this method adopts Aberth's algorithm which does not require computation of derivatives and determinants, and reduces the computational cost with two additional procedures, namely preconditioning using the coordinate transformation and pruning using Krawczyk's method. Numerical examples show that the proposed method gives the mapping degree with 2n+1 operations using interval arithmetic.

According to the Gestalt principals, this paper presents a recognition method of grouping areas in trademark images modeling features for measuring the attraction degree between couples of image components. This investigation would be used for content-based image retrieval from the view of mirroring human perception for images. Depending on variability in human perception for trademark images, the proposed method finds grouping areas by calculating Mahalanobis distance with the features to every combination of two components in images. The features are extracted from every combination of two components in images, and the features represent proximity, shape similarity, and closure between two components. In addition, changing combination of the features, plural grouping patterns are output. Besides, this paper shows the efficiency and limits of the proposed method from experimental results. In the experiments, 104 participants have perceived grouping patterns to 74 trademark images and the human perceptions have been compared with outputs by the proposed method for the 74 images.

In this paper, an automated computer-aided-detection scheme is proposed to identify and locate the suspicious masses in the abnormal breasts from the full mammograms. Mammograms are examined using a four-stage detection method including pre-processing, identification of local maxima, seeded region-growing, and false positive (FP) reduction. This method has been applied to the entire Mammographic Image Analysis Society (MIAS) database of 322 digitized mammograms containing 59 biopsy-proven masses in 56 images. Results of detection show 95% true positive (TP) fraction at 1.9 FPs per image for the 56 images and 1.3 FPs per image for the entire database.

The objective of this paper is to propose the Pulse Position Modulation (PPM) system which embeds the synchronizing signal in the information frame. In the proposed system, the frame for transmitting information is also the frame for acquiring frame timing. The data transmission rate of the proposed system is independent of the length of the synchronization signal because the proposed system does not require the synchronization frame. The data transmission rate and the synchronization performance for the proposed system are better than those of the conventional system.

We observe the inter-carrier interference (ICI) caused by channel variation of the fading in time domain in orthogonal frequency division multiplexing (OFDM) systems. This observation allows us to propose simple two-stage equalizer to minimize the ICI. Simulation results show that the bit error rate (BER) performance of the proposed equalizer with much reduced complexity is comparable with that of the classical frequency domain linear minimum mean squared error (MMSE) equalizer.

Uncertainty within one-wavelength (λ) is inevitable in an ultrasound positioning system that measures the time of flight of ultrasound pulses especially when a simple comparator is used for pulse detection. This paper proposes a compensation scheme based on pulse period adjustment. The test results show that the proposed scheme efficiently eliminates the 1λ-deviation and provides improved distance measurement.

A power and spreading gain allocation strategy is considered for effectively providing data services for mobile users with different levels of priorities in a DS-CDMA system supporting real-time and non-real-time services. Specifically, the uplink in the DS-CDMA system is considered subject to a constraint on total power received at the base station caused by non-real-time data services. The constraint is imposed to meet QoS requirements of real-time services. The priority level of a data user is specified by the weighting factor assigned to the data throughput of the user. Our strategy implements a relative prioritization that affords a trade-off between spectral efficiency and strict prioritization.

In this letter two noise-predictive equalization schemes, which are based on zero-forcing (ZF) and minimum mean square error (MMSE) criteria, are presented for unique-word (UW) based single-carrier systems. The correlation properties of the noises in the outputs of the frequency domain equalizer are exploited to predict and cancel the noise contained in the estimation of data. Theoretical analyses show that both of the proposed techniques perform better than the conventional frequency domain equalizers. Simulation results have confirmed the significant performance improvement they could achieve.

We introduce a new hierarchical key management scheme which can be applied for secure Mobile IP registration protocol. Contrary to the previous schemes, AAA protocol used for registration key distribution is separated from the base registration protocol, so that the registration key distribution can be simplified and the delay caused by the AAA protocol can be avoided. Also proposed is the non-repudiation service based on a hash chain, which is useful for secure auditing.

In this paper, the confinement loss of octagonal photonic crystal fibers (PCFs) with an isosceles triangle lattice of air-holes are numerically investigated. Taking into account the confinement loss, the mode field diameter (MFD), the effective area (Aeff) and the chromatic dispersion of octagonal PCFs are calculated, compared to conventional hexagonal PCFs. It is found from confinement loss and MFD results that the octagonal PCFs can confine the field strongly than the hexagonal PCFs due to the different air filling fraction. Moreover, it is shown that the octagonal PCFs are obtained not only positive but also negative larger dispersion values and smaller Aeff values compared to the hexagonal PCFs.

The most of conventional information services are based on the implicit premise that the users has already defined their desired information. This study proposes a mobile information service that allows the users who have not yet defined their desired information or whose desired information varies according to the situation to get appropriate information. When the user can specify their desired information to the system explicitly, the authors develop a "Pull" service. Conversely, when the user cannot verbally specify their desired information to the system, this study provides "Push" service and "Don't disturb" option for the user who does not welcome this service. This study considers the characteristics of the environment of mobile terminal to focus on "Time", "Place" and user's "Preference": long term and short term preference. This study also creates rules, algorithms and filtering to the service. Furthermore, the results of experiments have been discussed to verify the idea that different of user desired requires different information services.

The purpose of the study is to obtain the automatic and optimal matching between a motion-measurement device such as a data glove and an output device such as a dexterous robot hand, where there are many differences in the numbers of degree of freedom, sensor and actuator positions, and data format, by means of motion imitation by the humans. Through the algorithm proposed here, a system engineer or user need no labor of determining the values of gains and parameters to be used. In the system, a subject with data glove imitated the same motion with a dexterous robot hand which was moving according to a certain mathematical function. Autoregressive models were adapted to the matching, where each joint angle in the robot and data glove data of the human were used as object and explanatory variables respectively. The partial regression coefficients were estimated by means of singular value decomposition with a system-noise reduction algorithm utilizing statistical properties. The experimental results showed that the robot hand was controlled with high accuracy with small delay, suggesting that the method proposed in this study is proper and easy way and is adaptive to many other systems between a pair of motion-measurement device and output device.

The rapid hybrid acquisition of PN sequences is proposed for DS/CDMA systems. The system introduces the excision CFAR method into the background power estimation. A mathematical analysis is done for the single path and multipath environments. The detection performance of the proposed scheme is compared with that of other acquisition schemes. Results show that the proposed method has better detection performance if the excision coefficient is properly selected.

A new class of ternary sequence with a zero-correlation zone is introduced. The proposed sequence sets have a zero-correlation zone for both periodic and aperiodic correlation functions. The proposed sequences can be constructed from a pair of Hadamard matrices of size n0n0 and a Hadamard matrix of size n1n1. The constructed sequence set consists of n0 n1 ternary sequences, and the length of each sequence is (n1+1) for a non-negative integer m. The zero-correlation zone of the proposed sequences is |τ|≤ -1, where τ is the phase shift. The sequence member size of the proposed sequence set is equal to times that of the theoretical upper bound of the member size of a sequence set with a zero-correlation zone.

A reduced-sample-rate (RSR) sigma-delta-pipeline (SDP) analog-to-digital converter architecture suitable for high-resolution and high-speed applications with low oversampling ratios (OSR) is presented. The proposed architecture employs a class of high-order noise transfer function (NTF) with a novel pole-zero locations. A design methodology is developed to reach the optimum NTF. The optimum NTF determines the location of the non-zero poles improving the stability of the loop and implementing the reduced-sample-rate structure, simultaneously. Unity gain signal transfer function to mitigate the analog circuit imperfections, simplified analog implementation with reduced number of operational transconductance amplifiers (OTAs), and novel, aggressive yet stable NTF with high out of band gain to achieve larger peak signal-to-noise ratio (SNR) are the main features of the proposed NTF and ADC architecture. To verify the usefulness of the proposed architecture, NTF, and design methodology, two different cases are investigated. Simulation results show that with a 4th-order modulator, designed making use of the proposed approach, the maximum SNDR of 115 dB and 124.1 dB can be achieved with only OSR of 8, and 16 respectively.

Real-time object detection or recognition technology becomes more important for various intelligent vision systems. Processing models for object detection or recognition from natural images should tolerate pattern deformations and pattern position shifts. The hierarchical convolutional neural networks are considered as a promising model for robust object detection/recognition. This model requires huge computational power for a large number of multiply-and-accumulation operations. In order to apply this model to robot vision or various intelligent real-time vision systems, its LSI implementation is essential. This paper proposes a new algorithm for reducing multiply-and-accumulation operation by sorting neuron outputs by magnitude. We also propose an LSI architecture based on this algorithm. As a proof of concept for our LSI architecture, we have designed, fabricated and tested two test LSIs: a sorting LSI and an image-filtering LSI. The sorting LSI is designed based on the content addressable memory (CAM) circuit technology. The image-filtering LSI is designed for parallel processing by analog circuit array based on the merged/mixed analog-digital approach. We have verified the validity of our LSI architecture by measuring the LSIs.