TCP-Aware Uplink Scheduling for IEEE 802.16

In IEEE 802.16 networks, a bandwidth request-grant mechanism is used to accommodate various QoS requirements of heterogeneous traffic. However, it may not be effective for TCP flows since (a) there is no strict QoS requirement in TCP traffic; and (b) it is difficult to estimate the amount of required bandwidth due to dynamic changes of the sending rate. In this letter, we propose a new uplink scheduling scheme for best-effort TCP traffic in IEEE 802.16 networks. The proposed scheme does not need any bandwidth request process for allocation. Instead, it estimates the amount of bandwidth required for a flow based on its current sending rate. Through simulation, we show that the proposed scheme is effective to allocate bandwidth for TCP flows     

A Current-Gain Scheme for High Density and Low Voltage FeRAM

The proposed current-gain scheme provides a key technical solution for a high density, low cost and high performance ferroelectric random access memory. The proposed sensing scheme shows maximum sensing-signal window because of divided sub-bitline (SBL) structure. The unit cell array section is composed of the cell array of 64 rows and 128 columns with SBL, SBL switch (SBSW) devices and current-gain transistor (CGT) device. The global main bitline (MBL) is biased by MBL sensing load (MSL) device and connected to common MBL bus (CMB) through block selection switch (BSS) device. The device sizes of CGT and MSL devices are key factors for determining the transfer characteristics of SBL and MBL. The 128 sense amplifiers in peripheral circuit region are shared to all cell array blocks through CMB with 128 MBL columns of each cell array block. The address access time of the 16 Mb chip is evaluated to less than 70 ns at 3 V.     

Superiority demonstration of variance-considered machines by comparing error rate with support vector machines

To improve the performance of classification algorithms, we proposed a new varianceconsidered machine (VCM) classification algorithm in a previous study. The study showed theoretically that VCMs have lower error probabilities than SVMs. The purpose of this paper is to experimentally demonstrate the superiority of VCMs. Therefore, we verified our proposal with several case experiments using data following a Gaussian distribution with different variances and prior probabilities. To estimate performance, the experiment for each case was executed 1000 times and the error rates were averaged for accuracy. The data of each experiment have different distances between means of data, and different ratios between training data and testing data. Thus, we proved that the error rate of VCMs is lower than the error rate of SVMs, although their performances were not similar in each case. Consequently, we expect that VCMs will be applied to a variety fields.     

Effects of inductively coupled plasma conditions on the etch properties of GaN and ohmic contact formations

In this study, n-GaN was etched using inductively coupled Cl₂/H₂ plasmas and the effects of plasma conditions on the etch properties, surface composition and ohmic contact formation were investigated as a function of gas composition using OES (optical emission spectroscopy), SEM (scanning electron microscope), XPS (X-ray photoelectron spectroscopy), AES (Auger electron spectroscopy) and TLM (transmission line method). The addition of hydrogen to Cl₂ plasma decreased GaN etch rate and changed the surface composition from Ga-rich to N-rich. Etched profiles were near vertical with a smooth sidewall, however, the pure Cl₂ case showed the most anisotropic etch profile. Specific contact resistivity was increased with increasing hydrogen percent in Cl₂/H₂, however, most of contact resistivities of the contacts fabricated on the GaN etched with Cl₂/H₂ (≤75% H₂) were less than those fabricated on the non-etched GaN.     

Development of an auto-welding system for CRD nozzle repair welds using a 3D laser vision sensor

A control rod device (CRD) nozzle attaches to the hemispherical surface of a reactor head with J-groove welding. Primary water stress corrosion cracking (PWSCC) causes degradation in these welds, which requires that these defect areas be repaired. To perform this repair welding automatically on a complicated weld groove shape, an auto-welding system was developed incorporating a laser vision sensor that measures the 3-dimensional (3D) shape of the groove and a weld-path creation program that calculates the weld-path parameters. Welding trials with a J-groove workpiece were performed to establish a basis for developing this auto-welding system. Because the reactor head is placed on a lay down support, the outer-most region of the CRD nozzle has restricted access. Due to this tight space, several parameters of the design, such as size, weight and movement of the auto-welding system, had to be carefully considered. The cross section of the J-groove weld is basically an oval shape where the included angle of the J-groove ranges from 0 to 57 degrees. To measure the complex shape, we used double lasers coupled to a single charge coupled device (CCD) camera. We then developed a program to generate the weld-path parameters using the measured 3D shape as a basis. The program has the ability to determine the first and final welding positions and to calculate all weld-path parameters. An optimized image-processing algorithm was applied to resolve noise interference and diffused reflection of the joint surfaces. The auto-welding system is composed of a 4-axis manipulator, gas tungsten arc welding (GTAW) power supply, an optimized designed and manufactured GTAW torch and a 3D laser vision sensor. Through welding trials with 0 and 38-degree included-angle workpieces with both J-groove and U-groove weld, the performance of this auto-welding system was qualified for field application.     

Recycling wasted scallop shell as an adsorbent for the removal of phosphate

Lots of scallop shells were discharged from local restaurants and marine product manufacturers around the city of Gangneung and most of them are dumped into landfill. The scallop shell was recycled as an adsorbent for the removal of phosphate. The shell size greatly affected phosphate removal. One gram of shell having diameter of around 45 μm removed 100 mg/L of phosphate in 3 h while that of 3 mm hardly removed in 80 h. Phosphate removal was not much affected by the pH in the range of 2.0–7.5 but it was scarcely removed beyond pH 8.0. Higher temperature was preferred for phosphate removal but the removal efficiency was almost constant over 35 °C. The maximum phosphate removal capacity was obtained through Langmuir isotherm plotting and it was as high as 23.0 mg-phosphate/g-shell. On the purpose of enhancing the adsorption capacity of scallop shell, it was treated with chemical reagents such as HCl, NaOH, NH₄HCO₃ and EDTA. HCl-treatment increased the adsorption capacity of the shell having diameter of 45 μm by 39.8% than raw scallop shell, but the treatment showed negligible effect on the shell of 1000 μm in diameter. Packed-bed containing HCl-treated scallop shell with 500 μm in diameter removed 20 mg/L of phosphate stably for 15 days and the removal efficiency was over 85% throughout operation.     

Ring sensor and heart rate monitoring system for sensor network applications

A ring-type pulse oximeter sensor attached to the finger and its 24-hour ambulatory heart rate monitoring system are presented. The PCB has been designed with a light-to-frequency converter and the CPU with a built-in Zigbee stack for simple and low power consumption. Also designed is the algorithm using a least square estimator to calibrate various signal distortions caused by motion artefacts for a proper accuracy.     

Characteristics of hydrogenated silicon thin film deposited by RF-PECVD using He-SiH4 mixture

Nanocrystalline silicon thin films (nc-Si:H) were deposited using He as the dilution gas instead of H₂ and the effect of the operating pressure and rf power on their characteristics was investigated. Especially, operating pressures higher than 4 Torr and a low SiH₄ containing gas mixture, that is, SiH₄(3 sccm)/He(500 sccm) were used to induce high pressure depletion (HPD) conditions. Increasing the operating pressure decreased the deposition rate, however at pressures higher than 6 Torr, crystallized silicon thin films could be obtained at an rf power of 100 W. The deposition of highly crystallized nc-Si:H thin film was related to the HPD conditions, where the damage is decreased through the decrease in the bombardment energy at the high pressure and the crystallization of the deposited silicon thin film is increased through the increased hydrogen content in the plasma caused by the depletion of SiH₄. When the rf power was set at a fixed operating pressure of 6 Torr, HPD conditions were obtained in the rf power range from 80 to 100 W, which was high enough to dissociate SiH₄ fully, but meantime low enough not to damage the surface by ion bombardment. At 6 Torr of operating pressure and 100 W of rf power, the nc-Si:H having the crystallization volume fraction of 67% could be obtained with the deposition rate of 0.28 nm/s.     

Clinical and microbiological effects of minocycline-loaded microcapsules in adult periodontitis

Clinical and microbiological effects of subgingival delivery of 10% minocycline-loaded (MC), bioabsorbable microcapsules were examined in 15 adult periodontitis patients. Patients received oral hygiene instruction 2 weeks prior to the study. At baseline (day 0) all teeth received supragingival scaling (SC); 2 quadrants received no further treatment and 1 quadrant received subgingival scaling and root planning (SRP). In the fourth quadrant, the tooth with the deepest probing sites (at least 1 site > or = 5 mm) was treated with minocycline microcapsules. The sites were evaluated at baseline and weeks 1, 2, 4, and 6. Clinical indices included bleeding on probing (BOP), probing depths (PD), and attachment loss (AL). Microbiological evaluations included percent morphotypes by phase-contrast microscopy; cultivable anaerobic, aerobic, and black-pigmented Bacteroides (BPB); and percent Porphyromonas gingivalis, Prevotella intermedia, Eikenella corrodens, and Actinomyces viscosus by indirect immunofluorescence. In the SC + MC group, BOP, PD, and AL were significantly reduced from baseline for weeks 1 to 6. BOP in the SC + MC group was significantly reduced compared to the SRP group from weeks 2 to 6. In the SC + MC group the percent of spirochetes and motile rods decreased and the percent of cocci increased after 1 week. The increased cocci and decreased motile rods were statistically greater at weeks 4 and 6 in the SC + MC group compared to the SRP group. This study demonstrates that local subgingival delivery of 10% minocycline-loaded microcapsules as an adjunct to scaling results in reduction in the percent sites bleeding on probing greater than scaling and root planning alone and induces a microbial response more favorable for periodontal health than scaling and root planing.