CDN (Content Delivery Networks) improves end-user performance by replicating web contents on a group of geographically distributed servers. However, repeatedly keeping the entire replica of the original objects into many content servers consumes too much server resource. This problem becomes more serious for the large-sized objects such as streaming media, e.g. high quality video. In this paper, we therefore propose an efficient replication method for layered video streams in CDN, which can reduce user response delays and storage costs simultaneously. Based on an analytical formulation of the cooperative replication of layers and segments of each video stream, we derive a replication algorithm which solves next three problems quantitatively. (1) How many servers should be selected to replicate a given video stream? (2) For a single video stream, how many layers and segments should be stored in a given server? (3) After selecting a group of servers for each video stream, how do we allocate the replication priority (i.e. order) to each server? Simulation results verify that the proposed algorithm efficiently resolves the above problems and provides much better performance than conventional methods.

This paper presents a novel layout approach using dual supply voltage technique. In Placing and Routing (P&R) phase, conventional approaches for dual supply voltages need to separate low supply voltage cells from high voltage ones. Consequently its layout tends to be complex compared with single supply voltage layout. Our layout approach uses cells having two supply voltage rails. Making these cells is difficult in bulk due to increase in area by n-well isolation or in delay by negative body bias caused by sharing n-well. On the other hand, making cells with two supply voltage rails is easy in body-tied PD-SOI owing to trench isolation of each body of transistor. Since our approach for dual supply voltages offers freedom for placement as much as conventional ones for single supply voltage, exsting P&R tools can be used without special operation. Simulation results with MCNC circuits and adders show that our approach reduces power by 23% and 25%, respectively, showing almost the same delay with single supply voltage layout.

A fully integrated current-steering 10-b CMOS Digital-to-Analog Converter with on-chip terminated resistors is presented. In order to improve the device-mismatching problem of internal termination resistors, a self-calibrated current bias circuit is designed. With the self-calibrated current bias circuit, the gain error of the output voltage swing is reduced within 0.5%. For the purpose of reducing glitch noises, furthermore, a novel current switch based on a deglitching circuit is proposed. The prototype circuit has been fabricated with a 3 V 0.35 µm 2-poly 3-metal CMOS technology, and it occupies 1350 µm750 µm silicon area with 45 mW power consumption. The measured INL and DNL are within 0.5LSB, respectively. The measured SFDR is about 65 dB, when an input signal is about 8 MHz at 100 MHz clock frequency.

In IP-based mobile networks, a few of mobility agents (e.g., home agent, foreign agent, etc.) are used for mobility management. Recently, Hierarchical Mobile IPv6 (HMIPv6) was proposed to reduce signaling overhead and handoff latency occurred in Mobile IPv6. In HMIPv6, a new mobility agent, called mobility anchor point (MAP), is deployed in order to handle binding update procedures locally. However, the MAP can be a single point of performance bottleneck when there are a lot of mobile node (MNs) performing frequent local movements. This is because the MAP takes binding update procedures as well as data packet tunneling. Therefore, it is required to control the number of MNs serviced by a single MAP. In this paper, we propose a load control scheme at the MAP utilizing an admission control algorithm. We name the proposed load control scheme proactive load control scheme to distinct from the existing load control schemes in cellular networks. In terms of admission control, we use the cutoff priority scheme. We develop Markov chain models for the proactive load control scheme and evaluate the ongoing MN dropping and the new MN blocking probabilities. As a result, the proactive load control scheme can reduce the ongoing MN dropping probability while keeping the new MN blocking probability to a reasonable level.

Ultrafast all-optical switching was experimentally demonstrated using four-wave mixing in an SOA. Two pump pulses with different wavelengths and timings were used for 12 switching. The cross-correlation measurements of FWM signals using a short reference pulse show the high-speed switching capability for wavelength routing in OTDM networks.

Some plants have air purification ability. This purification ability of plants is considered a promising method for indoor air purification because of the low cost and high purification performance. Therefore, several studies have been carried out to investigate the relationship between the air purification ability of plants and environmental conditions. Nevertheless, the purification mechanism and process have not been clarified yet. In this paper, we investigated the air purification process in plants by bioelectrical potential analysis using linear and nonlinear analysis methods. First, we showed that two types of plants have a high air purification ability; Schefflera and Boston fern. Next, we measured AC bioelectrical potential during the purifying process of plants for pollutant gas. Then, we evaluated the power spectra of time series data of the bioelectrical potential. We found that the power spectra shifted to a lower level after gas injection over all frequencies. Thus, the higher power spectrum came from possible higher physiological activities of the plant. Finally, we introduced a nonlinear analysis method from the dynamical system theory. We transformed the time series data of the potential to a higher dimensional state space using a delay coordinate, which is often used in the field of nonlinear time series analysis. The results show that the orbits in the reconstructed state space have a large variation in gas injection. These experimental results suggest that the measurement of bioelectrical potential could become a useful method for evaluating the air purification ability of plants.

In this paper, iterative adaptive soft parallel interference canceller (ASPIC) is proposed for turbo coded multiple-input multiple-output (MIMO) multiplexing. ASPIC is applied to transform a MIMO channel into single-input multiple-output (SIMO) channels for maximum ratio diversity combining (MRC). In the ASPIC, replicas of the interference are generated and subtracted from the received signals. For the generation of replicas with higher reliability, iterative ASPIC is proposed. It performs the iterative interference cancellation by feedback of the log-likelihood ratio (LLR) sequence obtained as the turbo decoder output. For iterative ASPIC, at the transmitter, the information sequence and parity sequence are transmitted from different antennas. In this paper, the achievable bit error rate (BER) performance, in a Rayleigh fading channel, for the turbo coded MIMO multiplexing with the proposed iterative ASPIC system is evaluated by computer simulation.

Displaying a 3D geometric model of a user in real time is an advantage for a telecommunication system because depth information is useful for nonverbal communication such as finger-pointing and gesturing that contain 3D information. However, the range image acquired by a rangefinder suffers from errors due to image noises and distortions in depth measurement. On the other hand, a 2D image is free from such errors. In this paper, we propose a new method for a shared space communication system that combines the advantages of both 2D and 3D representations. A user is represented as a 3D geometric model in order to exchange nonverbal communication cues. A background is displayed as a 2D image to give the user adequate information about the environment of the remote site. Additionally, a high-resolution texture taken by a video camera is projected onto the 3D geometric model of the user. This is done because the low resolution of the image acquired by the rangefinder makes it difficult to exchange facial expressions. Furthermore, to fill in the data occluded by the user, old pixel values are used for the user area in the 2D background image. We have constructed a prototype of a high presence shared space communication system based on our method. Through a number of experiments, we have found that our method is more effective for telecommunication than a method with only a 2D or 3D representation.

We propose a practical blind channel identification algorithm based on the principal component analysis. The algorithm estimates (1) the channel order, (2) the noise variance, and then identifies (3) the channel impulse response, from the autocorrelation of the channel output signal without using the eigenvalue and singular-value decomposition. The special features of the proposed algorithm are (1) practical method to find the channel order and (2) reduction of computational complexity. Numerical examples show the effectiveness of the proposed algorithm.

This study aims to identify grammatical relations (GRs) in Korean sentences. The key task is to find the GRs in sentences in terms of such GR categories as subject, object, and adverbial. To overcome this problem, we are faced with the structural ambiguity and the grammatical relational ambiguity. We propose a statistical model, which resolves the grammatical relational ambiguity first, and then resolves structural ambiguity by using the probabilities of the GRs given noun phrases and verb phrases in sentences. The proposed model uses the characteristics of the Korean language such as distance, no-crossing and case property. We showed that consideration of such characteristics produces better results than without consideration by experiments. We attempt to enhance our system by estimating the probabilities of the proposed model with the Maximum Entropy (ME) model, and with Support Vector Machines (SVM) classifiers and we confirm that SVM classifiers improved the performance of our proposed model through experiments. Through an experiment with a tree and GR tagged corpus for training the model, we achieved an overall accuracy of 84.8%, 94.1%, and 84.8% in identifying subject, object, and adverbial relations in sentences, respectively.

Currently, multi-party video conference does not provide equivalent quality in comparison to face-to-face conference. One assumed reason is that participants cannot be aware of "who is focusing on whom". We introduce virtual space to a multi-party conference system, allocating avatars in a space. We also introduce intuitive input interface using motion processor in order to construct a multi-party conference system, which the user can use without being aware of it. A new displaying method is essential for this system, and we introduce a way by which a user can obtain the feedback of which user he/she is focusing on. We introduce e-MulCS as the system that fulfils these proposals. By comparing this system with the video conference system, the results show that our system supports the intuitive multi-party communication better.

The growth of the Internet has resulted in an increasing need for personalized information systems. The paper describes an autonomous agent, the Web Robot Agent or WebBot, which integrates with the web and acts as a personal recommendation system that cooperates with the user in order to identify interesting pages. The Apriori algorithm extracts the characteristics of the web pages in the form of association words that are semantically related and mines a bag of association words. Using hybrid components from collaborative filtering and content-based filtering, this hybrid recommendation system can overcome the shortcomings associated with traditional recommendation systems. In this paper, we present an improved recommendation system, which uses the user preference mining through hybrid 2-way filtering. The proposed method was tested on a database, and its effectiveness compared with existent methods was proven in on-line experiments.

In this letter, we propose an approach to incorporate a statistical model for the voiced/unvoiced (V/UV) speech decision under background noise environments. Our approach consists of splitting the input noisy speech into two separate bands and applying a statistical model for each band. We compute and compare the likelihood ratio (LR) for each band based on the statistical model and estimated noise statistics for the V/UV decision. According to the simulation test, the proposed V/UV decision shows a better performance compared with the selectable mode vocoder (SMV) V/UV decision algorithm, particularly in clean and white noise environments.

Digital halftoning is used to quantize a grayscale image to a binary image. Error diffusion halftoning generates a high-quality binary image, but also generates some defects such as the warm effect, sharpening, and so forth. To reduce these defects, Kite proposed a modified threshold modulation method that utilizes a multiplicative parameter for controlling sharpening. Nevertheless, some degradation was observed near the edges of objects with a large luminance change. In this paper, we propose a method of controlling the multiplicative parameter in proportion to the magnitude of the local edge slope. The results of computer simulation show a greater reduction of sharpening in the halftone image. In particular, there is a great improvement in the quality of the edges of objects with a large luminance change.

In this paper, we propose a probabilistic feature-based parsing model for head-final languages, which can lead to an improvement of syntactic disambiguation while reducing the parsing cost related to lexical information. For effective syntactic disambiguation, the proposed parsing model utilizes several useful features such as a syntactic label feature, a content feature, a functional feature, and a size feature. Moreover, it is designed to be suitable for representing word order variation of non-head words in head-final languages. Experimental results show that the proposed parsing model performs better than previous lexicalized parsing models, although it has much less dependence on lexical information.

This paper presents a method for improving the performance of syntactic analysis by using accurate temporal expression processing. Temporal expression causes parsing errors due to its syntactic duality, but its resolution is not trivial since the syntactic role of temporal expression is understandable in the context. In our work, syntactic functions of temporal words are decisively identified based on local contexts of individual temporal words acquired from a large corpus, which are represented by a finite state method. Experimental results show how the proposed method, incorporated with parsing, improves the accuracy and efficiency of the syntactic analysis.

The polarized absorption measurement was employed to investigate the orientational order of the 4-n-4-pentyl-cyanobiphenyl (5CB) film of sub-nanometer thick. It was confirmed that this optical technique is simple but effective to observe the second orientational order parameter, S2, of the organic ultra thin film at the interface region.

This paper presents a novel ZVS bidirectional 1 kW class DC-DC converter used for a photovoltaic (PV) system. The proposed circuit is based on a boost&buckboost converter, which consists of a boost converter and a buckboost converter. Bidirectional soft switching is realized by using of coupled inductors and auxiliary switches in the circuit. From the analysis of the circuit operation, ZVS conditions of the switches are derived. In the experiment, the maximum efficiency of the proposed converter during forward power flow was 97.1% on output power of 320 W.

This paper presents a novel algorithm for crosspoint assignment (CPA) that takes into consideration crosstalk noise and shielding effects in deep sub-micron design. We introduce a conditional constraint which is imposed on a sensitive net-pair to detach one net from the other or to put another insensitive net between them for shielding. We provide two algorithms which can handle the conditional constraint: One is based on an ILP, which outputs an exact optimum solution. The other is a fast heuristics whose time complexity is O(n2 log n), where n is the number of pins. In experiments, we tested these algorithms for industrial examples. The results showed that the conditional constraint for shielding released algorithms from a tight space of feasible assignments. Our heuristics ran quickly and attained near optimum solutions.

We have demonstrated improvement in the efficiency of TDAPB-based OLEDs. The external quantum efficiency of 8.2% and a power efficiency of 17.3 lm/W were achieved. The results suggest that using the starburst small-molecule TDAPB allows for easy fabrication and is effective for achieving high efficiencies in simple device structures.