We have determined the thickness and optical constants (refractive index and extinction coefficient) of each layer in the multi-layer organic light emitting diode (OLED) devices based on phosphorescent platinum octaethyl porphine (PtOEP) using a phase modulated spectroscopic ellipsometer. The thickness of each layer estimated from the ellipsometric measurement is different from the thickness measured with quartz oscillator during the evaporation of organic materials. The deviation of total multi-layer thickness is about 5%, while the deviation in each of N, N'-bis(1-naphtyl)-N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD) and aluminum tris 8-hydroxyquinoline (Alq3) layers is about 20-25%. Additionally the spectra of refractive index and extinction coefficient of Alq3 and α-NPD layers are different from those that are measured using the single layer films. These results are understood by penetration of organic material from the neighboring layers in the multi-layer structure devices.

The Transduction Method is a powerful way to design logic circuits, utilizing already existing circuits. A set of permissible functions (SPF) plays an essential role in such circuit transformation/reduction, and is computed at each point (connection or gate output). Currently, two types of SPFs have been used: the maximum SPFs (MSPFs) and compatible SPFs (CSPFs). At each point, the MSPF is literally the set of all PF's, and CSPF is a subset of the MSPF. When CSPFs are calculated, priorities are first assigned to all gates in the circuit. Based on the priorities, it is decided which subset is to be selected as the CSPF. The quality of the results depends on the priorities. In this paper, the concept of super-sets of permissible functions (SSPFs) is introduced to reduce the effect of the priorities that CSPFs depend on. In order to loosen the dependency, each SSPF is computed to contain CSPFs which are candidates to be selected. The experimental results show that the SSPF-based Transduction Method has intermediate reduction capability and takes an intermediate computation time between the MSPF-based and CSPF-based ones. The capability and the time are considered as an acceptably good trade-off. In addition, without any transformations, since SSPFs are the maximum super-set, SSPFs are applicable for analyzing the maximum performance of the CSPF-based transformation, for comparison with the MSPF-based one. Theoretically, the number of connectable gate pairs detected by the MSPFs is 100%. According to the experimental results obtained using SSPFs, on average, 99% are detectable by SSPFs and 1% are detectable only by using the MSPFs. The results show that by using CSPFs, 72% of connectable gate pairs are detectable with any priority assignment and 99% (SSPFs capability) are detectable on average even when the best priorities are assigned. According to the experimental results of CSPF calculation with five priorities, 82% to 93% are practically detectable on average. This is the first quantitative analysis realized by SSPFs which compares the CSPF-based and MSPF-based Transduction Methods with respect to the coverage of PF's.

This paper proposes a Real-Time Compression Architecture (RTCA), which maximizes the efficiency of web services, while reducing the response time at the same time. The developed architecture not only guarantees the freshness of compressed contents but also minimizes the time needed to compress the message, especially when the traffic is heavy.

Iterative multiuser detection and space-time coding are two promising techniques to increase the capacity and performance of coded multiuser systems in wireless channels. In this paper, a low-complexity iterative multiuser receiver is proposed using combined group multiuser detection and interference cancellation for space-time block coded MC-CDMA system. Turbo code is used for outer channel coding with log-MAP decoding. In each group, consisting of smaller number of users, multiuser likelihood ratios can be computed by employing MAP-based approach by taking into account of all possible transmitted symbols within each STBC time slot for these users. Moreover, once decoding information of all users are available after the first iteration, soft interference cancellation can be used instead of groupwise MAP-based detection for lower complexity, without sacrificing the performance significantly. Simulation results are presented in a Rayleigh multipath fading environment. The proposed receiver offers performance very close to that of single user system within a few iterations of joint detection and decoding.

Imaging techniques for robots are important and meaningful in the near future. Pulse radar systems have a great potential for shape estimation and locationing of targets. They have an advantage that they can be used even in critical situations where optical techniques cannot be used. It is thus required to develop high-resolution imaging algorithms for pulse radar systems. High-resolution imaging algorithms utilize the carrier phase of received signals. However, their estimation accuracy suffers degradation due to phase rotation of the received signal because the phase depends on the shape of the target. In this paper, we propose a phase compensation algorithm for high-resolution pulse radar systems. The proposed algorithm works well with SEABED algorithm, which is a non-parametric algorithm of estimating target shapes based on a reversible transform. The theory is presented first and numerical simulation results follow. We show the estimation accuracy is remarkably improved without sacrificing the resolution using the proposed algorithm.

In this paper, a new computing paradigm suitable for analog circuit systems is described in comparison to the digital circuit systems. The analog circuit systems have some disadvantages especially in terms of accuracy and stability, but there are some applications that don't require accuracy or stability in circuit component. The new computing concept for such applications, 'inaccurate' information processing, or 'rough' information processing, is proposed and described as well as some examples of such applications.

The Hidden Markov Model (HMM) is a popular statistical framework for modeling and analyzing stochastic signals. In this paper, a novel strategy is proposed that makes use of level-building algorithm with a chain of AdaBoost HMM classifiers to model long stochastic processes. AdaBoost HMM classifier belongs to the class of multiple-HMM classifier. It is specially trained to identify samples with erratic distributions. By connecting the AdaBoost HMM classifiers, processes of arbitrary length can be modeled. A probability trellis is created to store the accumulated probabilities, starting frames and indices of each reference model. By backtracking the trellis, a sequence of best-matched AdaBoost HMM classifiers can be decoded. The proposed method is applied to visual speech processing. A selected number of words and phrases are decomposed into sequences of visual speech units using both the proposed strategy and the conventional level-building on HMM method. Experimental results show that the proposed strategy is able to more accurately decompose words/phrases in visual speech than the conventional approach.

This paper proposes a simple method for estimation and compensation of signal direction, to deal with relative change of sound source location caused by the movements of a microphone array and a sound source. This method introduces a delay filter that has shifted and sampled sinc functions. This paper presents a concept for the joint optimization of arrival time differences and of the coordinate system of a mobile microphone array. We use the LMS algorithm to derive this method by maintaining a certain relationship between the directions of the microphone array and the sound source directions. This method directly estimates the relative directions of the microphone array to the sound source directions by minimizing the relative differences of arrival time among the observed signals, not by estimating the time difference of arrival (TDOA) between two observed signals. This method also compensates the time delay of the observed signals simultaneously, and it has a feature to maintain that the output signals are in phase. Simulation results support effectiveness of the method.

This paper presents a model-based study of SET (Single-Electron-Transistor) logic gate family for synthesizing binary, MV (Multiple-Valued) and mixed-mode logic circuits. The use of SETs combined with MOS transistors allows compact realization of basic logic functions that exhibit periodic transfer characteristics. The operation of basic SET logic gates is successfully confirmed through SPICE circuit simulation based on the physical device model of SETs. The proposed SET logic gates are useful for implementing binary logic circuits, MV logic circuits and binary-MV mixed-mode logic circuits in a highly flexible manner. As an example, this paper describes design of various parallel counters for carry-propagation-free arithmetic, where MV signals are effectively used to achieve higher functionality with lower hardware complexity.

In this paper, we propose a formal method for detection of three automation surprises in human-machine interaction; a mode confusion, a refusal state, and a blocking state. The mode confusion arises when a machine is in a different mode from that anticipated by the user, and is the most famous automation surprise. The refusal state is a situation that the machine does not respond to a command the user executes. The blocking state is a situation where an internal event occurs, leading to change of an interface the user does not know. In order to detect these phenomena, we propose a composite model in which a machine and a user model evolve concurrently. We show that the detection of these phenomena in human-machine interaction can be reduced to a reachability problem in the composite model.

Masqueraders who impersonate other users pose serious threat to computer security. Unfortunately, firewalls or misuse-based intrusion detection systems are generally ineffective in detecting masqueraders. Anomaly detection techniques have been proposed as a complementary approach to overcome such limitations. However, they are not accurate enough in detection, and the rate of false alarm is too high for the technique to be applied in practice. For example, recent empirical studies on masquerade detection using UNIX commands found the accuracy to be below 70%. In this research, we performed a comparative study to investigate the effectiveness of SVM (Support Vector Machine) technique using the same data set and configuration reported in the previous experiments. In order to improve accuracy of masquerade detection, we used command frequencies in sliding windows as feature sets. In addition, we chose to ignore commands commonly used by all the users and introduce the concept of voting engine. Though still imperfect, we were able to improve the accuracy of masquerade detection to 80.1% and 94.8%, whereas previous studies reported accuracy of 69.3% and 62.8% in the same configurations. This study convincingly demonstrates that SVM is useful as an anomaly detection technique and that there are several advantages SVM offers as a tool to detect masqueraders.

We have investigated the pretilt angle of liquid crystal (LC) molecules induced by photo-alignment films of polyimide (Azo-PI) containing azobenzene in the backbone structure. To generate finite pretilt angles, the Azo-PI film with inclined alignment of the backbone structure was prepared by a double light-exposure method. In this method the corresponding polyamic acid (Azo-PAA) film was first exposed to linearly polarized ultraviolet/visible (UV/VIS) light (LP-light) at normal incidence, and then oblique angle irradiation of unpolarized UV/VIS light (UP-light) was performed in the plane of incidence perpendicular to the polarization direction of the LP-light. Repeated photo-isomerization reactions of azobenzene induce the alignment of the Azo-PAA backbone structure. By thermally imidizing the photo-treated film we obtained a thermally and optically stable Azo-PI film. The orientational distribution of the Azo-PI backbone structure was determined by measuring the polarized infrared absorption spectra as a function of the sample rotation angle and the angle of incidence. The pretilt angle of LC molecules was determined by a crystal rotation method. We found that the average inclination angle of the Azo-PI backbone structure increased with the UP-light exposure. The pretilt angle of LC molecules, measured from the surface plane, also increased with the UP-light exposure. We succeeded in generating a pretilt angle of 3. The relation between the LC pretilt angle and the average inclination angle of the Azo-PI backbone structure is discussed.

This paper is concerned with the signal processing aspects of the recently proposed interleave-division multiple-access (IDMA) scheme. We propose several low-cost detection algorithms to solve the problems of multiple-access, cross-antenna and intersymbol interference (ISI). The complexities (per user) of these algorithms are very low and increase either linearly or quadratically with the number of paths. It is shown that an IDMA system with a rate- 16-state convolutional code and a length-8 spreading sequence can support more than 100 users in a multipath fading channel with two receive antennas. This clearly indicates the great potential of IDMA systems.

In this paper, we consider a blind channel estimation and equalization for single input multiple output (SIMO) channels. It is based on the one-step forward multichannel linear prediction error method. The derivation of the existing method is based on the noiseless assumption, however, we analyze the effects of additive noise at the output of the one-step forward multichannel linear prediction error filters. Moreover, we derive analytical results for the error in the blind channel estimation and equalization using linear prediction.

The MPEG-2 Test Model 5 (TM5) algorithm describes a rate control method which consists of three steps: bit allocation, rate control and modulation. In TM5, however, buffer overflow and picture quality degradation may occur at the end of the GOP because the target bits and the actual coding bits for each picture do not match well. This paper presents a new bit rate control algorithm for matching the target and the actual coding bits based on accurate bit allocation. The key idea of the proposed algorithm is to determine quantization parameters which enable us to generate the actual coding bits close to the target bits for each picture, while improving the picture quality. The proposed algorithm exploits the relationship between the number of the actual coding bits and the number of the estimated bits of the previous macroblock within a picture.

We have developed a quick battery checker the Li-ion battery packs used in mobile phones. It checks for capacity deterioration by using an impedance-measuring method. Our previous measurements of the capacity and impedance at 1 kHz for various battery packs proved conclusively that there is a strong correlation between degraded capacity and impedance. The battery checker's design took into account the results we obtained from measuring impedances. We showed that the battery checker is highly accurate and fast.

The effect of feedback delay and channel estimation error on closed-loop transmit diversity (CTD) systems is investigated in time-selective Rayleigh fading channels. Based on a minimum mean square error (MMSE) channel estimator, the variance of the estimation error is formulated in terms of fading index and the number of transmit antennas. A bit error rate (BER) expression for the CTD system is analytically derived as a function of channel estimation error, feedback delay, and fading index. It is shown that the BER performance of the CTD system improves as the length of training symbols increases and/or the frame length decreases. In the CTD system, more accurate channel estimation scheme is required to achieve its full gain as the number of employed transmit antennas increases. It is also found that the CTD system is applicable to the slowly moving channel environments, such as pedestrians, but not for fast moving vehicles.

A high accuracy numerical technique based on the Finite Difference Time Domain (FDTD) method for a long dipole antenna analysis is presented. An improvement of the accuracy can be achieved without reducing the cell size by incorporating a quasi-static field behavior into the FDTD update equations. A closed form of the quasi-static field is obtained from a low frequency limit of a sinusoidal current distribution. The validity of the proposed algorithm is confirmed even when the length of dipole antenna is longer than half wavelength by comparing the results with the Method of Moment.

Fairness is one of the most important features of a rate allocation strategy. Proportional fairness criterion has been recently proposed by F. P. Kelly and his colleagues. In this paper, we have proposed a two-level hierarchical technique which allocates proportionally-fair rates to the network elastic users. Part of the network links which are used commonly by the end-users and are congestion prone, constitute the higher (first) level of the hierarchy. In this level, the users with common path in the network are grouped as virtual users. End-users and remaining network links constitute the lower (second) level of hierarchy. To improve the convergence rate of the algorithm, a combination of Jacobi method and fuzzy techniques is deployed in the higher level of hierarchy. Implementing such fast algorithms in the higher level (which is topologically simpler than the whole network), reduces the computational complexity with respect to the use of such algorithms in the whole network. Additionally, the lower level penalty function computation is done once in each N iterations, which reduces the computational complexity furthermore. The simulation results show that the proposed algorithm outperforms that of Kelly in the convergence speed.

Application of multipled block codes (MBCs) for realizing new flexible and efficient transmission systems that feature in hunting-free reframing and asynchronous multiplexing is investigated. First, the principles of MBC are overviewed to show the capacities of filterless clock recovery. Then it is shown that modification of simple frame structure of MBC line code can be used for attaining hunting-free reframing for multiplexing systems. Two types of MBCs are developed to this end. While the one uses header blocks for hunting-free reframing, the other uses distributed frame patterns. Header design of multipled block codes (MBC) for hunting-free reframing (HFR) is investigated for frame patterns with and without violation compensation. The feasibility of hunting-free reframing is tested in an experimental system. Application of hunting-free reframing to asynchronous multiplexing is also investigated and tested in an experimental system. Finally, advantages of hunting-free multiplexing systems are discussed.