Japanese terrestrial digital broadcasting (ISDB-T) began in 2003. To spread its signals throughout the country, optical fibers will be used to complement radio-wave networks. This paper describes recent applications of optical transmission of ISDB-T. It also describes our research on re-transmission with 40-GHz Radio On Fiber technology.

The abstract ray-tracing problem asks, for a given scene consisting of a light source, a light receiver and finitely many obstacles in a space, and a given positive integer ε > 0, whether a ray going out from the light source could reach the light receiver with intensity at least ε. The problem is known to be PSPACE-hard, and it is very unlikely that there exists an efficient algorithm to solve the problem without adding any restriction. In this paper, we show that the problem can be solved in polynomial time under some weak practical restrictions.

Many immersive displays developed in previous researches are strongly influenced by the design concept of the CAVE, which is the origin of the immersive displays. In the view of human-scale interactive system for virtual environment (VE), the existing immersive systems are not enough to use the potential of a human sense further extent. The displays require more complicated structure for flexible extension, and are more restrictive to user's movement. Therefore we propose a novel multi-projector display for immersive VE with haptic interface for more flexible and dynamic interaction. The display part of our system named "D-vision" has a hybrid curved screen which consist of compound prototype with flat and curve screen. This renders images seamlessly in real time, and generates high-quality stereovision by PC cluster and two-pass technology. Furthermore a human-scale string-based haptic device will integrate with the D-vision for more interactive and immersive VE. In this paper, we show an overview of the D-vision and technologies used for the human-scale haptic interface.

As a blind linear-interference-canceller for DS-CDMA mobile communications, the orthogonal matched filter (OMF) minimizes the power of the output while maintaining constant power of the desired signal in the output. This paper studies the extension of OMF to an RAKE receiver (OMF-RAKE), which adaptively controls the steering vectors that determine the constraint. It also applies the QR-RLS algorithm to estimate the OMF-RAKE parameters and investigates a hardware implementation that employs a systolic array. Computer simulations show that OMF-RAKE with the QR-RLS algorithm and the systolic array structure can reduce the computational complexity to about a half that of the conventional RLS-type algorithm without degrading the BER.

We present a simple decoding algorithm that modifies soft bit-flipping algorithm for decoding LDPC codes. In our method, a new parameter is explored to distinguish the variables (symbols) belonging to the same number of unsatisfied constraints. A token is also assigned in the method to avoid repeated flipping of the same variable, rather than using a constant taboo length. Our scheme shows a similar computational load as the taboo-based algorithm, while having a similar decoding performance as the belief propagation algorithm.

This paper demonstrates an on-chip di/dt detector circuit. The di/dt detector circuit consists of a power supply line, an underlying spiral inductor and an amplifier. The mutual inductor induces a di/dt proportional voltage, and the amplifier amplifies and outputs the value. The measurement results show that the di/dt detector output and the voltage difference between a resistor have good agreement. The di/dt reduction by a decoupling capacitor is also measured using the di/dt detector.

Most of commercial websites provide customers with menu-driven navigation and keyword search. However, these inconvenient interfaces increase the number of mouse clicks and decrease customers' interest in surfing the websites. To resolve the problem, we propose an information retrieval assistant using a natural language interface in online sales domains. The information retrieval assistant has a client-server structure; a system connector and a NLP (natural language processing) server. The NLP server performs a linguistic analysis of users' queries with the help of coordinated NLP agents that are based on shallow NLP techniques. After receiving the results of the linguistic analysis from the NLP server, the system connector interacts with outer information provision systems such as conventional information retrieval systems and relational database management systems according to the analysis results. Owing to the client-server structure, we can easily add other information provision systems to the information retrieval assistant with trivial modifications of the NLP server. In addition, the information retrieval assistant guarantees fast responses because it uses shallow NLP techniques. In the preliminary experiment, as compared to the menu-driven system, we found that the information retrieval assistant could reduce the bothersome tasks such as menu selecting and mouse clicking because it provides a convenient natural language interface.

We report the empirically obtained conditions for the fusion splicing with photonic crystal fibers (PCF) having large mode areas. By controlling the arc-power and the arc-time of a conventional electric-arc fusion splicer, the splicing loss between two PCFs could be lowered down to 0.2 dB in average. For the splicing PCF with a conventional single mode fiber (SMF), the loss was increased due to the modal field mismatch, but still below 0.45 dB in average. The tensile strength was weakened by the splicing from 2.83 GPa down to 1.04 GPa for the PCF-PCF case and 0.89 GPa for the PCF-SMF one.

We present measurements of Gate-Induced-Drain-Leak-age at various temperatures and terminal biases. Besides Band-to-Band tunneling leakage observed at high Drain-to-Gate voltage VDG, we also observed Trap-Assisted-Tunneling leakage current at lower VDG. Based on ISE TCAD simulations of the electric field, we propose analytical models for Band-to-Band and Trap-Assisted Gate-Induced-Drain-Leakage currents suitable for compact modeling.

To understand radio propagation structures and consider signal recovering techniques in mobile communications, it is most effective to estimate the signal parameters (e.g., DOA) of individual incoming waves. Also, in radar systems, it is required to discriminate the desired signal from interference. As one of the high-resolution DOA estimators, MUSIC and ESPRIT have attracted considerable attention in recent years. They need the eigenvectors of the correlation matrix and therefore we have to execute the EVD (eigenvalue decomposition) of correlation matrix. However, the EVD generally brings us a heavy computational load and as a result it is difficult to realize the real-time DOA estimator, which will be useful as a multibeam-forming algorithm for adaptive antennas. This paper focuses on MUSIC and ESPRIT using subspace tracking methods, such as BiSVD, PAST, and PASTd, to carry out iterative DOA estimation. Then, they are compared through computer simulation. Adaptive beamforming based on DCMP and MLM is also mentioned and an example is shown.

New decoding algorithms for binary linear codes based on the concave-convex procedure are presented. Numerical experiments show that the proposed decoding algorithms surpass Belief Propagation (BP) decoding in error performance. Average computational complexity of one of the proposed decoding algorithms is only a few times greater than that of the BP decoding.

We have implemented a distributed sensor system based on an array of fiber Bragg gratings (FBGs), which can measure up to 1000 points with a single piece of fiber. The system consists of FBGs having the same resonant wavelengths and small reflectivities (0.1 dB), and a wavelength tunable optical time-domain reflectometer (OTDR). To interrogate the distributed grating sensors and to address the event locations simultaneously, we have utilized the tunable OTDR. A thermoelectric temperature controller was used to tune the emission wavelength of the OTDR. The operating temperature of the laser diode was changed. By tuning the pulse wavelength of the OTDR, we could identify the FBGs whose resonant wavelengths were under change within the operating wavelength range of the DFB LD. A novel sensor cable with dry core structure and tensile cable was fabricated to realize significant construction savings at an industrial field and in-door and out-door applications. For experiments, a sensor cable having 52 gratings with 10 m separations was fabricated. To prevent confusion with unexpected signals from the front-panel connector zone of the OTDR, a 1 km buffer cable was installed in front of the OTDR. The proposed system could distinguish and locate the gratings that were under temperature variation from 20 to 70.

In this paper, we present the classification of small antennas based on statistical data. The three categories of downsizing methods are loading a matching circuit, changing the current path, and using dielectric/magnetic materials. These categories are explained using several examples. In this paper, we show that the miminum Q value as a fundamental limit defined by an infinitesimal dipole is effective for determining the index factor of small antennas. Radiation efficiency measurements for small antennas are also discussed.

Web browsing task is based on depth-first searching scheme, so that searching relevant information from Web may be very tedious. In this paper, we propose personal browsing assistant system based on user intentions modeling. Before explicitly requested by a user, this system can analyze the prefetched resources from the hyperlinked Webpages and compare them with the estimated user intention, so that it can help him to make a better decision like which Webpage should be requested next. More important problem is the semantic heterogeneity between Web spaces. It makes the understandability of locally annotated resources more difficult. We apply semantic annotation, which is a transcoding procedure with the global ontology. Therefore, each local metadata can be semantically enriched, and efficiently comparable. As testing bed of our experiment, we organized three different online clothes stores whose images are annotated by semantically heterogeneous metadata. We simulated virtual customers navigating these cyberspaces. According to the predefined preferences of customer models, they conducted comparison-shopping. We have shown the reasonability of supporting the Web browsing, and its performance was evaluated as measuring the total size of browsed hyperspace.

This paper reports on the bending loss insensitive single mode fiber suitable for access networks, which is applicable for wide wavelength use. Excellent attenuation stability of the fiber in the full spectrum range has been confirmed even in severe conditions such as fiber handling in mid-span access at aerial closure, cable installation/handling in indoor wirings and so on. Also, applications suitable for FTTH subscribers' use have been introduced.

Side channel attacks (SCA) are serious attacks on mobile devices. In SCA, the attacker can observe the side channel information while the device performs the cryptographic operations, and he/she can detect the secret stored in the device using such side channel information. Ha-Moon proposed a novel countermeasure against side channel attacks in elliptic curve cryptosystems (ECC). The countermeasure is based on the signed scalar multiplication with randomized concept, and does not pay the penalty of speed. Ha-Moon proved that the countermeasure is secure against side channel attack theoretically, and confirmed its immunity experimentally. Thus Ha-Moon's countermeasure seems to be very attractive. In this paper we propose a novel attack against Ha-Moon's countermeasure, and show that the countermeasure is vulnerable to the proposed attack. The proposed attack utilizes a Markov chain for detecting the secret. The attacker determines the transitions in the Markov chain using side channel information, then detects the relation between consecutive two bits of the secret key, instead of bits of the secret key as they are. The use of such relations drastically reduces the search space for the secret key, and the attacker can easily reveal the secret. In fact, around twenty observations of execution of the countermeasure are sufficient to detect the secret in the case of the standard sizes of ECC. Therefore, the single use of Ha-Moon's countermeasure is not recommended for cryptographic use.

In medical education, many of computerized Problem-Based Learning (PBL) systems are used into their training curricula. But these systems do not truly reflect the situations which practitioners may actually encounter in a real medical environment, and hence their effectiveness as learning tools is somewhat limited. Therefore, the present study analyzes the computerized PBL teaching case, and considers how a clinical teaching case can best be presented to the student. Specifically, this paper attempts to develop a web-based PBL system which emulates the real clinical situation by introducing the concept of a "time sequence" within each teaching case. The proposed system has been installed in the medical center of National Cheng Kung University in Taiwan for testing purposes. The participants in this study were 50 of 5th grade (equivalent to 1st grade students in a medical school of the American medical education system) students for the evaluation process. Some experiments are conducted to verify the advantages of designing teaching cases with the concept of the "time sequence."

A new inductance extraction technique of spiral inductor from measurement fixture is presented. We propose a scalable expression of parasitic inductance for interconnects, and design consideration of test structure accommodating spiral inductor. The simple expression includes mutual inductance between the interconnects with high accuracy. The formula matches a commercial field solver inductance values within 1.4%. The layout of the test structure to reduce magnetic coupling between the spiral and the interconnects allows us to extract the intrinsic inductance of spiral more accurately. The proposed technique requires neither special fixture used for measurement-based method nor skilled worker for precise extraction with the analytical technique used.

A test structure and method for two-dimensional analysis of fabrication process variation of MOSFET using a photoemission microscope are presented. Arrays of 2010 (=200) MOSFETs were successfully measured at a time and evaluated the fluctuation of their characteristics. The fluctuation of hot-carrier-induced photoemission intensity was larger as gate length becomes smaller. Although the intensity fluctuation of photoemission in the same MOSFET was within small range, the fluctuation all over the MOSFET array was relatively large and independent of the position in the array. An estimation method of the gate length fluctuation has been demonstrated with the photoemission intensity distribution analysis.

We propose guidelines for LSI-chip design, taking the within-die variations into consideration, and for process quality improvement to suppress the variations. The auto-correlation length, λ, of device variation is shown to be a useful measure to treat the systematic variations in a chip. We may neglect the systematic variation in chips within the range of λ, while σ2 of the systematic variation must be added to σ2 of the random variation outside the λ. The random variations, on the other hand, exhibit complete randomness even in the closest pair transistors. The mismatch variations in transistor pairs were enhanced by 1.41(=) compared with the random variations in single transistors. This requires careful choice of gate size in designing a transistor pair with a minimum size, such as transfer gates in an SRAM cell. Poly-Si gate formation is estimated to be the most important process to ensure the spatial uniformity in transistor current and to enhance circuit performance. Large relative variations are observed for the contact to p+ diffusion, via1 (M1-M2), and via2 (M2-M3) among parameter variations in passive elements. The standard deviations for random variations in via1 and via2 are noticeably widespread, indicating the importance of the via resistance control in BEOL. The spatial frequency power spectrum for within-die random variations is confirmed experimentally, as uniform ('white') with respect to the spatial frequency. To treat the large 'white random noise,' the least-square method with a 4th-order polynomial exhibits a best efficiency as a fitting function for decomposing the raw variation data into systematic part and random part.