A novel phase noise reduction technique in oscillators usingdefected ground structure

A new technique to reduce the phase noise in microwave oscillators is developed using the resonant characteristic of the defected ground structure (DGS). Two kinds of oscillators have been designed and measured for the examination of the reduction of phase noise by the DGS. The first adopts the DGS section under the microstrip line at the gate circuit, while the second has only the conventional microstrip line. Measurement shows reduced phase noise by 10-15 dB in the oscillator with the DGS compared to the conventional one     

Intelligent adaptive process control using dynamic deadband for semiconductor manufacturing

This paper proposes an efficient control method to minimize process error and to reduce process variance in semiconductor manufacturing. The photolithography (photo) process forms a complex semiconductor circuit and is important for quality. Obstacles to the process include the facility itself, vibration, wear and tear, product/process changes and environmental influences. Control methodologies being currently used to address these issues often amplify the variation of the process by failing to perform adequate process control. Therefore, this paper proposes an effective process control method to reduce process variance by quickly detecting and identifying process disturbances and accurately reflecting the degree of change to process control. This study proposes dynamic deadband control that uses a region (band) to detect the status of a process change. It adjusts the process control based on the changes detected. In this research, the semiconductor manufacturing company is supported to perform control that is more precise and reduces fluctuations by producing products of uniform quality. In addition, it can contribute to yield due to the quality incentive and increased process control of semiconductor manufacturing.     

Study on photocatalysis of TiO 2 nanotubes prepared by methanol-thermal synthesis at low temperature

TiO₂ nanotubes were synthesized by the solvothermal process at low temperature in a highly alkaline water–methanol mixed solution. Their characteristics were identified by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (BET), Fourier transform infrared spectroscopy (FTIR) and UV–Vis absorption spectroscopy. The as-prepared samples were tested by the photodegradation reaction of methylene blue (MB) dye under visible-light irradiation. The ratios of methanol and water, as well as calcination temperature, affected the morphology, nanostructure and photocatalytic performance. The methanol solvent plays an important role in improving crystallization of the anatase phase, which affects the photocatalytic reaction. Titanate nanotubes were synthesized in methanol–water volume ratios of 10:90, 20:80 and 30:70 which still had high absorbability. Titania nanotubes formed at a calcination temperature of 300 °C using methanol–water volume ratio of 30:70 showed highest photocatalytic performance, much higher than that using water solvent and TiO₂–P25 powder.     

Etching characteristics of thin SiON films using a liquefied perfluorocarbon precursor of C6F12O with a low global warming potential

Perfluorocarbon gas is widely used in the semiconductor industry. However, perfluorocarbon has a negative effect on the global environment owing to its high global warming potential (GWP) value. An alternative solution is essential. Therefore, we evaluated the possibility of replacing conventional perfluorocarbon etching gases such as CHF₃ with C₆F₁₂O, which has a low GWP and is in a liquid state at room temperature. In this study, silicon oxynitride (SiON) films were plasma-etched using inductively coupled CF₄ +C₆F₁₂O+O₂ mixed plasmas. Subsequently, the etching characteristics of the film, such as etching rate, etching profile, selectivity over Si, and photoresist, were investigated. A double Langmuir probe was used and optical emission spectroscopy was performed for plasma diagnostics. In addition, a contact angle goniometer and x-ray photoelectron spectroscope were used to confirm the change in the surface properties of the etched SiON film surface. Consequently, the etching characteristics of the C₆F₁₂O mixed plasma exhibited a lower etching rate, higher SiON/Si selectivity, lower plasma damage, and more vertical etched profiles than the conventional CHF₃ mixed plasma. In addition, the C₆F₁₂O gas can be recovered in the liquid state, thereby decreasing global warming. These results confirmed that the C₆F₁₂O precursor can sufficiently replace the conventional etching gas.     

Morphological control of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> particles via glycothermal process

Acicular magnetite (Fe₃O₄) powders were synthesized through new glycothermal dehydration by using crystalline α-FeOOH as precursor and glycols as solvent. When ethylene glycol was used as solvent, the phase was in-situ transformed from acicular α-FeOOH to α-Fe₂O₃ and finally to Fe₃O₄ at 270 °C for 6 h without morphological change. When water was added as a co-solvent in glycothermal reaction, Fe₃O₄ powders were synthesized through dissolution–recrystallization process at 230 °C for 3 h. The volume ratio of ethylene glycol to water (E/W) in the reaction has a strong effect on the morphology of the synthesized Fe₃O₄ particles. The particle shape of Fe₃O₄ particles changed from needle to sphere when the water content in E/W volume ratio increased from 0.5 to 1 mL in mixed glycothermal condition. When the water were added by more than 10 ml, the particle shape of Fe₃O₄ changed from sphere to octahedron truncated with the {100} faces and finally distinct octahedron with only {111} faces. Also, it is demonstrated that the size of Fe₃O₄ particles can be controlled from 1–2 μm to 100–200 nm by varying the reaction conditions such as the volume ratio of water to ethylene glycol and additive in glycothermal reaction.     

Real-time hazardous traffic condition warning system: framework and evaluation

This study presents a warning information system based on an innovate methodology to estimate accident likelihood in real time. Bayesian modeling approach implemented by the probabilistic neural network (PNN) is conducted to identify hazardous traffic conditions leading to potential accident occurrence. The proposed system displays warning signs to call drivers' attention for safer and careful driving once hazardous traffic conditions are observed by evaluating accident likelihood. It is believed that the proposed system to produce effective warning information for real-time safety enhancement could be a valuable tool to highway users and operators.     

Characteristics and Functional Properties of Protein Isolates from Various Peanut (Arachis hypogaea L.) Cultivars

Protein isolates from 9 cultivars of peanut (Arachis hypogaea L.) were compared. Sephadex G-200 gel filtration and nondenaturing polyacrylamide gel electrophoresis (NPAGE) of the protein isolates showed very similar patterns of arachin and nonarachin fractions. The content of individual fractions was somewhat different among cultivars, possibly indicating genetic variability. Sodium dodecyl sulfate-PAGE (SDS-PAGE) showed that the protein isolates had extremely complex sub-unit compositions. The content of acidic amino acids of the protein isolates was 34–38%, basic was 15–17%. Differences in some functionalities such as solubility and emulsification activity were conspicuous among cultivars.     

Multipath channel parameter estimation not requiring priorinformation of the number of received rays

The authors present an algorithm for multipath channel parameter estimation using an improved Prony method. This algorithm applies a modified optimally regularised spectral estimation to the conventional Prony method. This method needs no a priori information on the number of multipaths. The performance of the presented algorithm is almost the same as that of the SVD based multipath channel parameter estimation algorithm     

Rice flour — A functional ingredient for premium crabstick

This study was performed to evaluate rice flour as a functional ingredient for premium crabstick and develop a commercially viable recipe. Physicochemical properties of crabstick pastes with 42% surimi, with various rice flour concentrations (0, 1, 3, and 5%), and other ingredients were evaluated. The physical properties were measured during refrigeration and frozen storage. Rice flour measured at various concentrations (5 to 40% in water) using a DSC demonstrated similar patterns with an endothermic peak at around 63.5°C. During refrigerated storage, the strength of gels increased gradually, while cohesiveness stayed mostly unchanged. During frozen storage, water retention ability (WRA) gradually decreased as freeze-thaw (F/T) cycles were extended, however the water reduction was minimized as rice flour concentration increased. The optimum level was 1% rice flour concentration for chilled and frozen crabstick. Two crabstick samples (control and 1% rice flour) demonstrated no difference in strength and cohesiveness.