A comparison of LII analysis results from numerical model and experiment at elevated surrounding pressures

With environmental concerns over emitted particulate matters(PM) from combustion systems, various researches have been conducted on reduction and measurement techniques of particulate matters. The LII analysis results from numerical models and experiments in an ethylene/air laminar diffusion flame at elevated pressure up to 2.0 MPa with laser fluence 0.07 J/cm², detection wavelength 400 nm were compared to validate a modified LII numerical model. The lifetime of the LII signal decreased as the elevated pressure increased, so that LII decay time also decreased in both results. In the aspect of heat transfer mechanism, it becomes earlier that dominant conduction starts. This shows that the results matched well under the pressure conditions. It is concluded that the LII numerical model could be applied to decide particle size in TIRE-LII at the high-pressure condition.     

Dye adsorption characteristics of alginate/polyaspartate hydrogels

This study examined the removal of some basic dyes, such as Methylene Blue, Malachite Green and Methyl Orange, using alginate or alginate/polyaspartate composite gel beads. The adsorption of dyes from aqueous solutions at 25 °C was examined using a batch sorption technique. The effects of CaCl₂ and the dye concentration on the adsorption were examined. Type-S adsorption isotherms were obtained, which is characteristic of a weak solute–solid interaction. The ionic interaction between the dye molecule and gel matrix appears to be responsible for the efficient adsorption of cationic dyes in this system. These results suggest that an alginate/polyaspartate gel can be used as an effective sorbent for water pollutants such as dyes, and the immobilization of these organic contaminants in the hydrogels from wastewater can solve one of the most important environmental problems in the related industry.     

Compact Dipole Antenna for Terrestrial Digital Multimedia Broadcasting Service

A compact dipole antenna for the terrestrial digital multimedia broadcasting (TDMB) application is presented. The length of the antenna is about 0.06λ at the TDMB resonance frequency of 190 MHz. Miniaturization of the antenna is achieved by using meander structures and lumped elements. The proposed antenna has two resonance frequencies and covers the TDMB band from 174 MHz to 216 MHz in Korea. The antenna has good impedance bandwidth and radiation characteristics for the TDMB. The experimental results of the designed dipole antenna are presented and analyzed.     

Channel width dependence of hot electron injection program/hot hole erase cycling behavior in silicon-oxide-nitride-oxide-silicon (SONOS) memories

The channel width dependence of hot electron injection program/hot hole erase cycling behavior in silicon-oxide-nitride-oxide-silicon (SONOS) memories is investigated. While the trapped charge profile-dependent overerasure is observed in 10-μm-wide device, it is suppressed in 0.22-μm-wide device. Both the overerasure suppression and gradual positive threshold voltage shift in narrow device are explained as an elevated hot hole injection efficiency followed by more pronounced redistribution of the hole profile in the channel-center and the suppression of the lateral migration of injected holes in the channel-edge, by combining the measured endurance characteristics and TCAD simulation results. Main physical mechanisms are three-dimensional distribution of the electric field by gate/drain voltage, increasing interface states, and their trapped charge with cycling in the channel-edge.     

Hard coating films based on organosilane-modified boehmite nanoparticles under UV/thermal dual curing

Hard coating sols and films were prepared for UV/thermal dual curing. The coating sols were composed of boehmite nanoparticles modified with organosilanes (e.g. methacryloxy-propyl trimethoxy silane, vinyl triethoxy silane, and 3-glycidoxy-propyltrimethoxy silane), a formulated initiator, and an inorganic or organic cross-linker as an additive. With this coating solution, hard coating films with a pencil hardness above 8H and transparency above 90% in the visible light range were prepared on poly(methyl methacrylate) substrates. In addition, the coating solution could be quickly cured in 35 min at a temperature of 100 °C by UV/thermal dual curing. The effects of the additive and initiator on the hardness and transparency of the resulting films are described.     

Effects of apartment building façade and balcony design on the reduction of exterior noise

The effects of building façade and balcony design on the reduction of exterior noise were investigated by measuring the noise from traffic at an apartment complex located by a road side as well as the sound field characteristics of an area surrounded by four apartment buildings. The efficiency of different balcony forms for reducing exterior noise was determined using a 1:50 scale model and a single spark source. It was found that parapets were more effective in reducing exterior noise than lintels. Based on the measurements of the parapet used for this study and the absorptive materials in the scale model, a maximum noise reduction of 23 dB was obtained. Lastly, a computer simulation was conducted in order to predict the noise reduction level of lintels and parapets. The results of the simulation were compared to the results of the scale model test. Our results indicate that this method of exterior noise reduction can be useful in high-rise buildings where tall barriers cannot be built.     

Microbial communities in activated sludge performing enhanced biological phosphorus removal in a sequencing batch reactor

Microbial communities of activated sludge in an anaerobic/aerobic sequencing batch reactor (SBR) supplied with acetate as sole carbon source were analyzed to identify the microorganisms responsible for enhanced biological phosphorus removal. Various analytical methods were used such as electron microscopy, quinone, slot hybridization, and 16S rRNA gene sequencing analyses. Electron photomicrographs showed that coccus-shaped microorganisms of about 1 microm diameter dominated the microbial communities of the activated sludge in the SBR, which had been operated for more than 18 months. These microorganisms contained polyphosphate granules and glycogen inclusions, which suggests that they are a type of phosphorus-accumulating organism. Quinones, slot hybridization, and 16S rRNA sequencing analyses showed that the members of the Proteobacteria beta subclass were the most abundant species and were affiliated with the Rhodocyclus-like group. Phylogenetic analysis revealed that the two dominating clones of the beta subclass were closely related to the Rhodocyclus-like group. It was concluded that the coccus-shaped organisms related to the Rhodocyclus-like group within the Proteobacteria beta subclass were the most dominant species believed responsible for biological phosphorus removal in SBR operation with acetate.     

Thermal performance analysis according to wood flooring structure for energy conservation in radiant floor heating systems

The aim of this study was to reduce energy consumption, especially heating, in buildings. Improvements in the thermal conductivity of wood flooring, which was considered to decrease heating between floors and the indoor areas, were investigated. Wood flooring components such as solid-wood, high-density fiberboard (HDF), adhesives and polyethylene generally exhibit low thermal conductivity. The thermal conductivity and transfer performance of 21 replicates of wood flooring materials generally used in Korea were measured. The thermal conductivity was measured by using the guarded hot plate method. The thermal conductivities differed according to the structure of the floorings. Laminate wood flooring exhibited the highest thermal conductivity because of its high density and thin layers compared to the other floorings. The thermal transfer performance differed according to the installation method. The floating installation method exhibited a lower thermal transfer speed than the adhesion installation method because of its air layers and polyethylene form.