A Framework for MPEG‐4 Contents Delivery over DMB

Digital Multimedia Broadcasting (DMB) is an upcoming standard in Korea used to provide mobile multimedia broadcasting service based on the Eureka‐147 Digital Audio Broadcasting (DAB) system. The current dominant multimedia coding standard, MPEG‐4, is foreseen to play an important role in forthcoming DMB services. However, the current approaches for transporting MPEG‐4 content over DMB networks are not optimized. To address this issue we propose a novel MPEG‐4 stream multiplexer, called M4SMux, which provides better stream multiplexing and delivery over DMB networks. M4SMux features an MPEG‐4 elementary‐stream interleaving mechanism that reduces the multiplexing overhead and a multiplex configuration mechanism that utilizes M4SLinkTable for easy content access. In addition, we propose an error correction method which enhances transport efficiency.     

Analysis of the hemispheric asymmetry using fractal dimension of a skeletonized cerebral surface

We investigated hemispheric asymmetry using the fractal dimension (FD) of the skeletonized cerebral surface. Sixty-two T1-weighted magnetic resonance imaging volumes from normal Korean adults were used. The skeletonization of binary volume data, which corresponded to the union of the gray matter and cerebrospinal flow classified by fuzzy clustering, was performed slice by slice in the sagittal direction, and then skeletonized slices were integrated into the three-dimensional (3-D) hemisphere. Finally, the FD of the 3-D skeletonized cerebral surface was calculated using the box-counting method. We measured the FD of the skeletonized cerebral surface and the volumes of intracranial gray matter and white matter for the whole hemispheres and obtained the hemispheric asymmetries of each measurement. The FD, the gray matter, and the white matter volumes for the whole hemispheres decreased in the old group. The asymmetry of the FD revealed a significant right-greater-than-left asymmetry showed rightward, but did not change according to age and gender. None of the intracranial gray matter or white matter volumes showed any significant asymmetric changes. It could be said that the FD of the skeletonized cerebral surface is a novel measure of cerebral asymmetry.     

A Discrete‐Amplitude Pulse Width Modulation for a High‐Efficiency Linear Power Amplifier

A new discrete‐amplitude pulse width modulation (DAPWM) scheme for a high‐efficiency linear power amplifier is proposed. A radio frequency (RF) input signal is divided into an envelope and a phase modulated carrier. The low‐frequency envelope is modulated so that it can be represented by a pulse whose area is proportional to its amplitude. The modulated pulse has at least two different pulse amplitude levels in order that the duty ratios of the pulse are kept large for small input. Then, an RF pulse train is generated by mixing the modulated envelope with the phase modulated carrier. The RF pulse train is amplified by a switching‐mode power amplifier, and the original RF input signal is restored by a band pass filter. Because duty ratios of the RF pulse train are kept large in spite of a small input envelope, the DAPWM technique can reduce loss from harmonic components. Furthermore, it reduces filtering efforts required to suppress harmonic components. Simulations show that the overall efficiency of the pulsed power amplifier with DAPWM is about 60.3% for a mobile WiMax signal. This is approximately a 73% increase compared to a pulsed power amplifier with PWM.     

Personally customizable content authoring service for Internet Protocol television subscribers

In this paper, we propose a personally customizable content authoring service (C2Channel) using an Internet Protocol television (IPTV) platform, in which a user terminal such as a PC or set‐top box sends various kinds of multimedia files from a camera or camcorder to a remotely located authoring server (C2Channel server). The C2Channel server creates personalized content in real time by combining special effects with the multimedia files transmitted from the user terminal and then retransmits them to a predefined relevant service group as a personal IPTV channel through an IPTV network provider. This content authoring service supplies an automatic multimedia editing/composition service and offers unicast, multicast, and groupcast services for a large number of interested groups via an IPTV‐based real‐time media delivery platform (Open Live IPTV Engine [OLIVE]), in which a service management server is used for user identification through the IPTV personal channel. Because this platform uses a remote server resource when authoring personally customizable content, resources remaining at the user's terminal can be variously utilized. Copyright © 2012 John Wiley & Sons, Ltd.     

Effects of vapor-annealed gate dielectric on the properties of zinc tin oxide transparent thin film transistors

We investigated the effects of vapor-annealed gate dielectrics on the mobility, threshold voltage, and other characteristics of bottom gate zinc tin oxide (ZTO) transparent thin film transistors (TTFTs). Here, Al₂O₃ films coated on dry oxidized Si wafers were annealed in a water vapor atmosphere before ZTO deposition and used as TTFT gate dielectrics. The vapor-annealed ZTO TTFTs exhibited 50% higher mobility than those that were not vapor annealed. This improvement in mobility is ascribed to the hydrogen passivation in the amorphous ZTO films     

Hydrogenated amorphous silicon thin film transistor fabricated onplasma treated silicon nitride

We have demonstrated that the performance of the inverted staggered, hydrogenated amorphous silicon thin film transistor (a-Si:H TFT) is improved by a He, H₂, NH₃ or N₂ plasma treatment for a short time on the surface of silicon nitride (SiN _x) before a-Si:H deposition. With increasing plasma exposure time, the field-effect mobility increase at first and then decrease, but the threshold voltage changes little. The a-Si:H TFT with a 6-min N₂ plasma treatment on SiN_x exhibited a field effect mobility of 1.37 cm²/Vs, a threshold voltage of 4.2 V and a subthreshold slope of 0.34 V/dec. It is found that surface roughness of SiN_x is decreased and N concentration in the SiN _x at the surface region decreases using the plasma treatment     

A two-element antenna for suppression in multipath environments

The design of a two-element antenna for portable transceivers is considered. The antenna consists of a dipole terminated with a parallel loop-capacitor combination. The antenna has a single feed at a point on the loop opposite the junction and does not require external combining circuitry. The capacitor creates a phase shift between the dipole and loop currents, thereby greatly reducing the probability of deep s in the received signal when the antenna is deployed in free-space or in the vicinity of a fixed reflector, where standing wave patterns occur. Theoretical and simulation studies based on multiple incident/reflected plane wave fields typical of multipath environments are used to quantify the reduction in probability. Simulation results are presented for three antenna types: a dipole antenna, a loop-dipole antenna without a capacitor, and the loop-dipole antenna with capacitor. The results are verified by field measurements on an automated outdoor test range, where the incidence angle and distance from the reflector are varied. With a single incident plane wave, the loop-dipole-capacitor (LDC) design reduces the probability of deep s in the received signal by up to two orders of magnitude at low signal-to-noise ratios (SNRs) when compared with the standard dipole antenna and the loop-dipole antenna without the capacitor. The performance advantage of the new design decreases as the number of incident waves increases; however, it performs at least as well as the dipole antenna in all cases studied.     

Minimum time control of conductive heating systems formicroelectronics processing

A minimum time control scheme is designed to improve repeatability by minimizing the loading effects induced by the common processing condition of placement of a semiconductor wafer at ambient temperature on a large thermal-mass bake plate at processing temperature. The minimum time control strategy provides an optimal solution for minimizing the worst case deviation from a nominal temperature set-point during the load disturbance condition. This results in a predictive controller that performs a predetermined heating sequence prior to the arrival of the wafer as part of the resulting feedforward/feedback strategy to eliminate the load disturbance. The controller is easy to design and implement and makes it more suitable for online implementation such as automatic online tuning of a feedforward controller. Experimental results depict an order-of-magnitude improvement in the settling time and the integral-square temperature error between the optimal predictive controller and a feedback controller for a typical load disturbance     

An evaluation of the optical fiber beam as a force sensor

The present study reports the use of an intensity based plastic optical fiber (POF) as a force sensor. Different materials for beam, such as spring steel and mild steel, are used to evaluate the performance of the force sensor during macro-bending. The POF is surface bonded to a beam and subjected to force. The system relies on monitoring the light intensity, as the POF is subjected to transversal loading conditions. Experimentally obtained output of POF which could be measured with negligible hysteresis is compared with finite element analysis in the range between 0.0098 N to 19.613 N. The reproducibility of the sensor is observed in the limit of ±1%. The finding of this study highlights the potential use of POF sensors for various force sensing applications.     

A 3-DOF MR-Compatible Device for Magic Angle Related In Vivo Experiments

The "magic angle" effect consists of the increase in signal intensity observed at a tendon or cartilage in a magnetic resonance image, when the tissue is oriented at an angle of approximately 55deg with respect to the main magnetic field B₀. The exploitation of this phenomenon is often used to assist diagnosis of tendinous and other diseases, although practical difficulties derived from positioning target tissue at the desired orientation inside closed-bore scanners has made this exploitation hard to implement. A 3-DOF MR-compatible mechatronic system has been developed to position a variety of limbs at the magic angle inside a closed- bore scanner, actuated by a custom-developed pneumatic air motor. The system is capable of locating the desired anatomy with high accuracy, and is designed to position the target tissue at a minimal distance from the isocenter. The compatibility of the system is demonstrated, producing negligible artifacts and an insignificant reduction in signal to noise of the image. Preliminary clinical trials scanning the Achilles tendon of healthy volunteers prove the functionality of the device. An increase in signal intensity of up to 21-fold has been recorded in the tendon at the magic angle.