• Asian Journal of Atmospheric Environment
• /
• v.11 no.1
• /
• pp.37-53
• /
• 2017

The effectiveness of four air fresher (AF) systems was evaluated with respect to their removal efficiencies against offensive odorants. For this purpose, malodorous species were generated by exposing freshly cooked foods emitting odorants with levels moderately above their respective threshold values in a confined room. The deodorization efficiency of the four AF systems was then tested for a period of 30 min by estimating the extent of reduction in odorant levels after the operation of each AF. The removal efficiency of the four AF units against each odorant was evaluated as follows: (1) between AF products from different manufacturers, (2) between odorants and ultrafine particulate matter ($PM_{2.5}$), and (3) between operation and natural degassing. The average sorptive removal of odorants was generally <80% and considered less effective or non-effective relative to $PM_{2.5}$. Further examination of odor reduction, if evaluated in terms of odor indices like odor intensity (OI) and odor activity value (OAV), recorded a mean of 33% and 87%, respectively. The overall results of this study confirmed that all tested AF units were not effective to resolve odor problems created under our testing conditions.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.45 no.6
• /
• pp.162-169
• /
• 2008

Film restoration is to detect the location and extent of defected regions from a given movie film, and if present, to reconstruct the lost information of each regions. It has gained increasing attention by many researchers, to support multimedia service of high quality. Among artifacts, scratch is the most frequent degradation. In this paper, an automatic film line scratch removal system is developed that can detect and restore all kind of scratches. For this we use the spatial information of scratches: The scratch in old films has lower or higher brightness than neighboring pixels in its vicinity and usually appears as a vertically long thin line. Our systems consists of scratch detection and scratch restoration. The scratches of various types are detected by neural network based texture classifier and morphology-based shape filter and then the degraded regions are restored using bilinear interpolation. To assess the validity of the Proposed method, it has been tested with all kinds of scratches, and then experimental results show that the proposed approach is robust to various scratches and efficient to apply a real film removal system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07a
• /
• pp.46-49
• /
• 2003

Chemical mechanical polishing (CMP) is an essential dielectric planarization in multilayer microelectronic device fabrication. In the CMP process it is necessary to minimize the extent of surface defect formation while maintaining good planarity and optimal material removal rates. The polishing mechanism of W-CMP process has been reported as the repeated process of passive layer formation by oxidizer and abrasion action by slurry abrasives. Thus, it is important to understand the effect of oxidizer on W passivation layer, in order to obtain higher removal rate (RR) and very low non-uniformity (NU%) during W-CMP process. In this paper, we compared the effects of oxidizer or W-CMP process with three different kind of oxidizers with 5% hydrogen peroxide such as $Fe(NO_3)_3$, $H_2O_2$, and $KIO_3$. The difference in removal rate and roughness of W in stable and unstable slurries are believed to caused by modification in the mechanical behavior of $Al_3O_3$ particles in presence of surfactant stabilizing the slurry.

• Journal of Environmental Health Sciences
• /
• v.24 no.1
• /
• pp.132-140
• /
• 1998

Laboratory-scale experiments were conducted using a three-stage rotating biological contactor unit followed by lime precipitation and sedimentation with effluent recycle to the first stage. The purpose of this study was to evaluate the effects of hydraulic loadings of 0.031-0.076 $m^3/m^2/d and recycle ratio of 1 to 3 on the simultaneous removal of organics and nutrients from domestic wastewater. Lime was added to maintain pH of 10.4-11.0 in the coagulation-flocculation reactor. Results showed that the highest nitrogen removal rate of 70.5% occurred at the lower hydraulic loading of 0.031 $m^3/m^2/d at a recirculation rate of 300%, and similarly, highest nitrification occurred at the same hydraulic loading and recycle ratio. Concentration of ammonia nitrogen in the effluent was less than 1 mg/l at the same operating conditions for higher nitrogen removal. Whereas, high BOD and COD removal was observed at hydraulic loading rate of 0.054 $m^3/m^2/d, and high removal of organic matter was evident from the consistent low COD and BOD value. Results obtained from the operating condition of higher loading rate, 300% of recycle rate showed the highest removals. Increasing in recycle rate and hydraulic loading rate increased the volatile solids fraction of the sludges generated to the extent of 47% at 0.076 $m^3/m^2/d hydraulic loading and 300% recirculation rate. Since pH in the flocculator was maintained at the pH of 10.4-11.0, above 90% removal of phosphorus was obtained. Average concentration of suspended solids was always maintained over 40 mg/l in the effluent. Therefore an RBC unit operating at a hydraulic loading near 0.031 $m^3/m^2/d with a recycle rate of 300% is a viable and feasible alternate conditions to produce an effluent with relative low organic matter and phosphorus, provided that there is a neutralization unit to control the pH and SS of the effluent.

• Applied Chemistry for Engineering
• /
• v.4 no.4
• /
• pp.746-752
• /
• 1993

Quantitative measurements have been made by using equilibrium dialysis techniques on the extent of complexation between PCB and dissoved humic acid(HA). This research investigates the effectiveness of activated carbon adsorption for the removal of PCB from organic free water and humid acid background solution by using bench-scale equilibrium and rate tests. It was found that the extent of complexation depended on the pH, calcium concentration, ionic strength, and the concentration of humic acid. When HA was present, activated carbon capacity was greatly reduced due to complexation and competitive adsorption effects and the adsorption characteristics became complicated by the presence of various species such as the unassociated HA, PCB, and PCB-HA complexes.

• Journal of Korean Society on Water Environment
• /
• v.22 no.6
• /
• pp.1022-1030
• /
• 2006

Activated sludge reactors maintaining an MLSS of 3,000 mg/L and packed Bio Contact Media (BCM fixed beds) was studied in lab-scale to determine the optimal packing ratio and an HRT of aerobic reactor in terms of organic removal, nitrification, denitrification efficiencies. At all HRTs of 3 hr, 5 hr, 7 hr respectively, reactors without BCM, control reactors, had the lowest TCODcr removal efficiency about 74.6%, and reactors with the BCM packing ratios of 10%, 15%, 20% had a greater TCODcr removal efficiency above 81.4%. As HRT decreased, the TCODcr removal efficiency decreased also in all reactors. However, a better utilization of TCODcr even at a higher organic loading was observed in reactors with BCM. The nitrification efficiency at all reactors was greater than 94%, and reactor with 20% packing of BCM had the highest nitrification efficiency at 97.9% while the TKN loading increased at $0.085mgTKN/m^3{\ast}day$ as HRT decreased, In terms of denitrification efficiency, the reactor without BCM ranged from 11.6% to 13.7%, and the reactors with BCM ranged from 28.3% to 63.4% which suggests that the more BCM is packed in the reactors, the higher the denitrification efficiency is achieved. Two parallel $A^2/O$ systems maintaining an MLSS of 3,000 mg/L were operated to investigate the effect of BCM packing ratio of 20% on organic removal, nitrification, denitrification efficiencies. Packing with BCM in system of aerobic reactor affected the SCODcr removal efficiency that increased from 73% to 78%. The nitrification efficiency for both systems with or without BCM was greater than 95%. The denitrification efficiency of systems with BCM and without BCM was 85.8% and 81.8%, respectively which appears that the denitrification efficiency was increased slightly by packing BCM. Compared denitrification efficiency in $A^2/O$ system to previous experimental study with activated sludge reactors operates with the same HRT $A^2/O$ system showed only 29% greater denitrification efficiency. It suggests that $A^2/O$ system with BCM can achieve a similar level of denitrification efficiency when the HRT of anoxic reactor is decreased to some extent.

• Journal of Chest Surgery
• /
• v.41 no.6
• /
• pp.768-771
• /
• 2008

The use of IVUS provides information about the lumen and arterial wall, the location and extent of atherosclerotic plaque and the state of the arterial wall after PCi. The use of IVUS after insertion of an intracoronary stent has currently increased, while conflicting evidence exists concerning the long-term benefits of IVUS. We report here on a case of surgical removal of an entrapped and fractured IVUS catheter during insertion of intracoronary stents, and we include a review of the relevant literature.

• Carbon letters
• /
• v.9 no.4
• /
• pp.275-282
• /
• 2008

Chemically activated carbons were prepared from maize cobs, using phosphoric acid of variable concentration. The textural parameters of the activated carbons were determined from the nitrogen adsorption isotherms measured at 77 K. The chemistry of the carbon surface was determined by measuring the surface pH, the pHPZC and the concentration of the carbon - oxygen groups of the acid type on the carbon surface. Kinetics of Cr(VI) sorption/reduction was investigated at 303 K. Two processes were investigated in terms of kinetics and equilibrium namely; Cr(VI) removal and chromium sorption were studied at various initial pH (1-7). Removal of Cr(VI) shows a maximum at pH 2.5. At pH<2.5, sorption decreases because of the proton competition with evolved Cr(III) for ion exchange sites. The decrease of sorption at pH>2.5 is due to proton insufficiency and to the decrease of the extent of Cr(VI) reduction. The chemistry of the surface of activated carbon is an important factor in determining its adsorption capacity from aqueous solutions particularly when the sorption process involves ion exchange.

• Journal of Plant Biology
• /
• v.33 no.2
• /
• pp.135-140
• /
• 1990

The membrane potential in the subepidermal cells of Lemna gibba G3 fronds was measured in the dark with glass capillary microelectrodes. At pH 7, the membrane potential, approximately-215 mV, could be depolarized to -82∼-88 mV by 0.1 mM dicyclohexylcarbodiimide (DCCD) or by KCN at 0.3 mM or higher concentrations. When the pH of the medium was altered the potential showed reversible changes, while it revealed no response to the external pH changes when energy transduction across the membrane was being blocked by 0.1 mM DCCD. The results support an assumption that the active component of the membrane potential of Lemna subepidermal cells is generated by electrogenic H+ -pump. By the addition of 0.10∼5.00 mM salicylic acid(SA) to the bathing medium the membrane potential was depolarized to a great extent, and the removal of SA from the medium repolarized the potential showing almost complete recovery, 92.3∼97.6% to the initial levels. Although the potential was greatly depolarized by 5.0% or higher concentrations of dimethylsulfoxide (DMSO), the recovery rate by DMSO removal was decreased as the pretreatment concentration had increased. Twenty percent DMSO pretreatment limited the recovery at only 47.1%. The presence of SA in the bathing medium could reversibly increase the permeability of the plasmalemma. DMSO at its concentration of 5.0% or higher increased the permeability of the membrane by irrevesibly impairing the membrane component involved in the membrane permeability.

• Journal of Soil and Groundwater Environment
• /
• v.27 no.3
• /
• pp.41-49
• /
• 2022

This study utilized citric acid as a floating agent in biological denitrification process and assessed its role under different carbon supplying conditions. Several microcosm tests including citric acid active (CAA), precipitating tablet release active (PTRA) and floating tablet release active (FTRA) were conducted to evaluate nitrate denitrification efficacy. In CAA reactors, nitrate removal was accompanied by the formation of denitrification by-products such as nitrite and nitrous oxide, with the extent of nitrate removal being proportional to citric acid concentration. These results suggest that citric acid induced heterotrophic biological denitrification. PTRA reactor that incorporated CAA and the same electron donor showed a similar denitrification efficiency to CAA reactor. FTRA reactor, which contained the same amount of fumarate as PTRA, enhanced denitrification by 7% as compared to the PTRA reactor. The overall results of this work indicate that surplus citric acid can be efficiently utilized in heterotrophic denitrification.