This letter proposes novel optical fiber cables with extremely small cable diameter that employs rollable 20-fiber ribbons, which will improve fiber ribbon and cable productivity compared with optical fiber cable employing rollable 4-fiber ribbons. We fabricated the cables and investigated its feasibility in terms of high-count compactness, cable productivity, fiber strain induced by cable bending, optical loss characteristics and capacity for mass splicing. As a result, we confirmed the excellence of these cables and their fiber splicing workability.

This study examined the performance improvement of a photovoltaic (PV) array and inverter as well as their design, construction, and post-operation and management, which will become the key elements in future PV systems. In addition, it evaluated the performance characteristics of a 50 kW grid-connection PV system in Korea. According to the result of the evaluation, the PV array showed approximately 10% efficiency. The inverter was indicated to operate at > 90% efficiency regularly at > 400 W/m2 irradiation. The capture losses (Lc), system losses (Ls) and performance ratio were approximately 0.9 h/d, 0.3 h/d, and > 70%, respectively, indicating that the system was operating stably. In addition, while the Ls decreased rapidly due to the efficiency of the inverter, the performance ratio decreased markedly with increasing Lc due to the increase in temperature when the reference yield was > 5.0 h/d.

In a closed-loop scenario, the performance of transmit-diversity schemes for a multiple antenna system depends on the reliability of the channel state information (CSI). However, estimating the reliability of the instantaneous CSI at the transmitter is a challenging task. In this paper, we propose a robust transmit-diversity scheme for the case when the instantaneous CSI available at the transmitter is imperfect and its reliability is unknown to the transmitter. We show by simulation that our proposed scheme is efficient when the CSI reliability varies arbitrarily in every channel realization.

Energy efficiency is one of the most important attributes in sensor network protocols. In sensor nodes, communication related activities consume the major share of battery energy. Therefore, judicious choice of transmit power and frame size are very important to maximize the energy efficiency and hence the lifetime of nodes. While there have been a few recent studies on transmit power control implementation in sensor nodes, no report has thoroughly investigated transmit power control and the effect of its interplay with frame size on nodal energy saving. In this paper, we report our implementation of automatic transmit power control in wireless sensor nodes based on open loop parameters -- namely, link layer frame size, and close loop parameters -- namely, number of consecutive positive acknowledgments and receive signal strength. Our extensive indoor and outdoor experimental results show that, for low to moderate transmission distances, transmit power control has the energy saving benefit, and the larger the frame size the more the energy saving. At a higher transmission distance or at a more error-prone communication scenario, transmit power control as well as a large frame size are detrimental to energy saving performance. The results from this study could be useful in deciding power control strategies and optimum frame length.

This paper presents a paraunitary filter bank (PUFB) based on a direct lifting structure of a building block and its inverse transform for lossless-to-lossy image coding. Although the conventional lifting-based filter banks (LBFBs), which are constructed by lifting structures with integer coefficients and rounding operations, suffer from degradation of coding performance due to much rounding error generated by cascading lifting structures, our proposals can be applied to any PUFB without losing many ones because building blocks can be applied to every lifting block as it is. It is constructed with very simple structures and many rounding operations are eliminated. Additionally, the number of rounding operations is reduced more by using two-dimensional block transform (2DBT) of separated transform to each building block. As result, even though the proposed PUFBs require a little side information block (SIB), they show better coding performance in lossless-to-lossy image coding than the conventional ones.

Enclosures of electronic equipment are an important item to suppress the unwanted emissions from digital processing circuits. However, the shielding effect at high frequencies is decreased by slits and apertures of the enclosures. The method for evaluating shielding effect of enclosures above 1 GHz was investigated in this paper. A disc-cone antenna operated by an O/E converter was developed and the radiation property was calculated by the method of moment. The results indicated that the deviation between the calculation and the measurement value was within 3 dB in the case of that the antenna is operated in the frequency range from 1 GHz to 10 GHz. The antenna was placed in the enclosure model constructed with wire meshes and the shielding effects were calculated and measured from 1 GHz to 3 GHz. The results showed that the tendency of the calculated value closely agreed with that of the measured value. Using the antenna, the shielding effect of the PC cases were investigated from 1 GHz to 8 GHz. The results indicated that the shielding effect is decreased in proportion with the increase of frequency, and the careful design was important to maintain the shielding effect in this frequency range.

This paper investigates the closure properties of 1-inkdot nondeterministic Turing machines and 1-inkdot alternating Turing machines with only universal states which have sublogarithmic space. We show for example that the classes of sets accepted by these Turing machines are not closed under length-preserving homomorphism, concatenation with regular set, Kleene closure, and complementation.

In ubiquitous sensor networks, the estimation accuracy of a node location is limited due to the presence of non-line-of-sight (NLOS) paths. To mitigate the NLOS effects, this letter proposes a simple algorithm where NLOS identification is carried out using angle-of-arrival (AOA). Simulation results show that the use of AOA improves NLOS identification rates and location estimation accuracy.

This letter proposes closed form solutions to the L2-sensitivity minimization of second-order state-space digital filters with real poles. We consider two cases of second-order digital filters: distinct real poles and multiple real poles. In case of second-order digital filters, we can express the L2-sensitivity of second-order digital filters by a simple linear combination of exponential functions and formulate the L2-sensitivity minimization problem by a simple polynomial equation. As a result, the minimum L2-sensitivity realizations can be synthesized by only solving a fourth-degree polynomial equation, which can be analytically solved.

An implantable WBAN path-loss model for a capsule endoscopy which is used for examining digestive organs, is developed by conducting simulations and experiments. First, we performed FDTD simulations on implant WBAN propagation by using a numerical human model. Second, we performed FDTD simulations on a vessel that represents the human body. Third, we performed experiments using a vessel of the same dimensions as that used in the simulations. On the basis of the results of these simulations and experiments, we proposed the gradient and intercept parameters of the simple path-loss in-body propagation model.

This paper presents an integer discrete cosine transform (IntDCT) with only dyadic values such as k/2n (k, n∈ in N). Although some conventional IntDCTs have been proposed, they are not suitable for lossless-to-lossy image coding in low-bit-word-length (coefficients) due to the degradation of the frequency decomposition performance in the system. First, the proposed M-channel lossless Walsh-Hadamard transform (LWHT) can be constructed by only (log2M)-bit-word-length and has structural regularity. Then, our 8-channel IntDCT via LWHT keeps good coding performance even if low-bit-word-length is used because LWHT, which is main part of IntDCT, can be implemented by only 3-bit-word-length. Finally, the validity of our method is proved by showing the results of lossless-to-lossy image coding in low-bit-word-length.

Introducing adaptive online data compression at network-internal nodes is considered for alleviating traffic congestion on the network. In this paper, we assume that advanced relay nodes, which possess both a relay function (network resource) and a processing function (computational and storage resources), are placed inside the network, and we propose an adaptive online lossless packet compression scheme utilized at these nodes. This scheme selectively compresses a packet according to its waiting time in the queue during congestion. Through preliminary investigation using actual traffic datasets, we investigate the compression ratio and processing time of packet-by-packet compression in actual network environments. Then, by means of computer simulations, we show that the proposed scheme reduces the packet delay time and discard rate and investigate factors necessary in achieving efficient packet relay.

This paper proposes a sensing system for a behavior detection system using an ultrasonic oscillosensor and an air pressure sensor. The ultrasonic oscillosensor sensor has a cylindrical tank filled with water. It detects the vibration of the target object from the signal reflected from the water surface. This sensor can detect a biological vibration by setting to the bottom bed frame. The air pressure sensor consists of a polypropylene sheet and an air pressure sensor, and detects the pressure information by setting under the bed's mattress. An increase (decrease) in the load placed on the bed is detected by the increase (decrease) in the pressure of the air held in the tube attached to the sheet. We propose a behavior detection system using both sensors, complementally. The system recognizes three states (nobody in bed, keeping quiet in bed, moving in bed) using both sensors, and we detect the behavior before getting out of bed by recognized these states. Fuzzy logic plays a primary role in the system. As the fundamental experiment, we applied the system to five healthy volunteers, the system successfully recognized three states, and detected the behavior before getting out of bed. As the clinical experiment, we applied the system to four elderly patients with dementia, the system exactly detected the behavior before getting out of the bed with enough time for medical care support.

The scalability of three-stage Clos-network packet switches makes them an attractive approach in implementing large-size packet switches. However, the configuration time of Clos-network switches depends on both the buffering strategy used and the adopted configuration process. To reduce configuration time, this paper focuses on the so-called Memory-Space-Memory (MSM) Clos-network packet switch, where the switch modules in the first and third stages use memory to support resolution of output port contention. The configuration of these switches is then based on a process to dispatch cells from the first-stage modules to the third-stage modules. Therefore, the throughput of an MSM Clos-network switch depends on the dispatching scheme used. This paper introduces a cell dispatching scheme, called maximum weight matching dispatching (MWMD) scheme, for MSM Clos-network switches and a request queue structure in the first-stage modules. The MWMD scheme performs maximum weight matching, similar to that used for input-queued single-stage packet switches, that in combination with the request queues can achieve 100% throughput under independent and identical admissible traffic. This high throughput can be achieved without allocating buffers in the second stage and without expanding the second stage of this three-stage packet switch. A low-complexity dispatching scheme, the maximal oldest-cell-first matching dispatching (MOMD) scheme, is also introduced as an alternative to MWMD. The performance evaluation in this paper shows that MOMD achieves high throughput under unbalanced traffic through the execution of a finite number of iterations.

This paper proposes closed form solutions to the L2-sensitivity minimization subject to L2-scaling constraints for second-order state-space digital filters with real poles. We consider two cases of second-order digital filters: distinct real poles and multiple real poles. The proposed approach reduces the constrained optimization problem to an unconstrained optimization problem by appropriate variable transformation. We can express the L2-sensitivity by a simple linear combination of exponential functions and formulate the L2-sensitivity minimization problem by a simple polynomial equation. As a result, L2-sensitivity is expressed in closed form, and its minimization subject to L2-scaling constraints is achieved without iterative calculations.

Unlike the conventional plasma-TVs using the driving circuit with two polarities during the reset and address periods, the cost-effective driving circuit using only the positive voltage level during the reset and address periods is proposed and implemented in the 42-in. plasma-TV.

Dramatic gains in channel capacity can be achieved in the closed-loop MIMO system under the assumption that the base station (BS) can acquire the downlink channel state information (CSI) accurately. However, transmitting CSI with high precision is a heavy burden that wastes a lot of uplink bandwidth, while transmitting CSI within a limited bandwidth leads to the degradation of system performance. To address this problem, we propose a zero-overhead downlink CSI feedback scheme based on the hybrid pilot structure. The downlink CSI is contained in the hybrid pilots at mobile terminal (MT) side, fed back to BS via the uplink pilot channel, and recovered from hybrid pilot at BS side. Meanwhile the uplink channel is estimated based on the hybrid pilot at BS side. Since transmitting the hybrid pilots occupies the same bandwidth as transmitting traditional code division multiplexing based uplink pilots, no extra uplink channel bandwidth is occupied. Therefore, the overhead for downlink CSI feedback is zero. Moreover, the hybrid pilots are formed at MT side by superposing the received analog downlink pilots directly on the uplink pilots. Thus the downlink CSI estimation process is unnecessary at MT side, and MT's complexity can be reduced. Numerical Simulations prove that, the proposed downlink CSI feedback has the higher precision than the traditional feedback schemes while the overhead for downlink CSI feedback is zero.

This letter proposes a new multicast traffic control policy in TDM-PON, which differentially classifies multicast flows which have relatively many associated receivers as high-class, and multicast flows which have relatively few associated receivers as low-class. Simulation results confirm that the proposed policy can effectively enhance multicast performance regarding delay and loss, specifically important to multimedia services, compared to the legacy policy.

This paper considers a new reactive fast handover MIPv6 (FMIPv6) mechanism to minimize packet loss of the existing mechanism. The primary idea of the proposed reactive FMIPv6 mechanism is that the serving access router buffers packets toward the mobile node (MN) as soon as the link layer between MN and serving base station is disconnected. To implement the proposed mechanism, the router discovery message exchanged between MN and serving access router is extended. In addition, the IEEE 802.21 Media Independent Handover Function event service message is defined newly. Through analytic performance evaluation and experiments, the proposed reactive FMIPv6 mechanism can be shown to minimize packet loss much than the existing mechanism.

Objective assessment of image and video quality should be based on a correct understanding of subjective assessment by human observers. Previous models have incorporated the mechanisms of early visual processing in image quality metrics, enabling us to evaluate the visibility of errors from the original images. However, to understand how human observers perceive image quality, one should also consider higher stages of visual processing where perception is established. In higher stages, the visual system presumably represents a visual scene as a collection of meaningful components such as objects and events. Our recent psychophysical studies suggest two principles related to this level of processing. First, the human visual system integrates shape and color signals along perceived motion trajectories in order to improve visibility of the shape and color of moving objects. Second, the human visual system estimates surface reflectance properties like glossiness using simple image statistics rather than by inverse computation of image formation optics. Although the underlying neural mechanisms are still under investigation, these computational principles are potentially useful for the development of effective image processing technologies and for quality assessment. Ideally, if a model can specify how a given image is transformed into high-level scene representations in the human brain, it would predict many aspects of subjective image quality, including fidelity and naturalness.