• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.40 no.4
• /
• pp.59-65
• /
• 2008

Electrochemical properties of pulp fiber could be modified by LbL(Layer-by-Layer) multilayering. Salt concentration and pH affect the conformation and ionization degree of polyelectrolyte. In this study, therefore, we intended to evaluate the effect of pH and salt concentration in polyelectrolyte multilayering on the electrochemical properties of pulp fiber. The pH of the stock was varied to 4, 7, and 10. Salt concentration was controlled at 0.001, 0.003, and 0.005 M of NaCl. Higher zeta potential was obtained when pulp fibers were multilayered at the condition of higher pH and higher salt concentration. The final zeta potential of pulp fiber after multilayering was dependent on the adsorption ratio of polyelectrolyte and the initial zeta potential of fibers.

• Nuclear Engineering and Technology
• /
• v.56 no.2
• /
• pp.419-425
• /
• 2024

The purpose of this study is to improve the concentration of U(VI) in carbonate solution reasonably, which to improve the application potential of the alkaline reprocessing processes. The dissolution behavior of U₃O₈ in carbonate peroxide solutions was investigated under different conditions, including pH, carbonate concentration, and solid-liquid ratio. The results showed that the dissolution rate of U₃O₈ increased with the increase of pH from 8 to 11 in the mixed carbonate solution containing 0.5 mol/L H₂O₂. The role of carbonate ions in the dissolution of U₃O₈ was further elucidated by observing the dissolution of UO₄⋅4H₂O in carbonate solutions. Furthermore, the concentration of U(VI) in 3 mol/L Na₂CO₃ solution was successfully increased to 350 g/L under ultrasonic-assisted conditions at 60 ℃ and a solid-liquid ratio at 1/2 g/mL. Meanwhile, it is suggested that increasing the concentration of carbonate ions can improve the stability of the dissolved solution containing uranyl peroxycarbonate complex.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.1-3
• /
• 2003

In this study, spectroradiometer data were coupled with fluorometer data to find out the best suited bands ratio to monitor the chlorophyll a concentration for inland water. Remote sensing reflectance measurements were used to evaluate the performance of several default ocean color chlorophyll algorithms for SeaWiFS data. This study shows that the chlorophyll a concentration from fluorometer and reflectance from spectroradiometer lies in exploiting the signal provided by the chlorophyll a red absorption peak near 670nm. Two-band ratio based on a ratio of reflectance 670 and 700nm provided a good correlation for a linear model, compare with blue-green two band ratio.

• Journal of applied mathematics & informatics
• /
• v.8 no.2
• /
• pp.417-428
• /
• 2001

Spatial distribution of groundwater contaminant concentration has special characteristics such as approximate symmetric profile, for example, in the transversal direction to groundwater flow direction, a certain ratio in directional propagation distances, etc. To obtain a geophysically appropriate semivariogram which is a key factor in estimation of groundwater contaminant concentration at desired locations, these special characteristics should be considered. Specifically, the concepts of symmetry and ratio are considered in this paper. By applying these two concepts, significant improvement of semivariograms, estimation variances, and final estimation results compared with the ones by conventional approaches which usually do not account for symmetry and ratio are shown using field experimental data.

• Journal of Korean Society for Atmospheric Environment
• /
• v.18 no.3
• /
• pp.247-252
• /
• 2002

In this technical information, the TSP measurement data at Gosan between 1992 and 1999 are presented and analyzed. The average ratio of N $O_3$$^{[-10]}$ /nss-S $O_4$$^{2-}$ is highest in March. The annual average ratio concentration of N $O_3$$^{[-10]}$ increased and it was found that the annual average ratio of N $O_3$$^{[-10]}$ /nss-S $O_4$$^{2-}$ increased during the period, probably due to the change of emission characteristics of China.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.659-660
• /
• 2006

High-aspect-ratio(max. 12.5) microchannels with excellent surface quality and good shape uniformity have been realized utilizing laser-induced etching technique. Etch width and depth variations depend largely upon process variables such as laser power and etchant concentration. Etchant concentration in association with viscosity also influence on the cross-sectional profile of the channels. The optimum process conditions for the fabrication of high-aspect-ratio microchannels applicable to micro thermal devices are demonstrated.

• Elastomers and Composites
• /
• v.33 no.5
• /
• pp.363-369
• /
• 1998

Photografting reaction onto styrene-butadiene rubber (SBR) as a function of monomer concentration, irradiation time and carbon black content has been studied using ultraviolet (UV). Acrylamide and benzophenone are used as monomer and photoinitiator, respectively. FT-IR ATR and static contact angle analysis using distilled water are used to measure the graft ratio of acrylamide onto SBR surface. Graft ratio of acrylamide increases with acrylamide concentration and irradiation time and contact angle tends to decrease with increasing graft ratio. It is observed that graft ratio increases with carbon black content.

• Journal of Environmental Health Sciences
• /
• v.18 no.1
• /
• pp.47-57
• /
• 1992

This study was performed to evaluate contamination degree of heavy metals in sediments of Han River, compared with other nation's evaluation method. The results were as follows 1. The contamination Ratio calculation method by heavy metal concentration in differnt fraction size has a limitation to apply to all of the areas of Han river because of its characteristics of sediment. As a result, this method applied to only 4 areas of Pal Dang, Wang Sook Chon, Uk Chon, and Bul Kwang Chon, and Contmination Ratio of heavy metals in those areas were relatively low of below 3. So it's considered that those areas have less contaminated from anthropogenic contaminants. 2. The Contamination Ratio calculation method by heavy metal concentration in different areasthat of upper area to be background level-has a limitation also to apply to Han river. But it is considered that this method was relatively suitable to apply, so it should be prepared evaluation standand method for them. Contamination ratio from background level as Pal Dang area were most high in An Yang Chon. So it must be prepared purification and control measure at An Yang Chon.

• KIEAE Journal
• /
• v.2 no.3
• /
• pp.33-38
• /
• 2002

The intermediate range of temperatures($100{\sim}300^{\circ}C$) which can be achieved with CPCs(Compound Parabolic Concentrators) without tracking device provides both economic and thermal advantages for solar collector design. The present paper summarizes critical design considerations for CPC with cylindrical absorber and its optical performance using ray tracing program. Concentration ratios vary as acceptance half angle, ratio of reflector height to aperture width and ratio of reflector area to aperture area. This effects showed that the concentration ratio was increased as acceptance angle but optimum ratio of reflector height to aperture width existed at critical value. As a result of ray tracing, solar ray losses was maximized at acceptance half angle and this problem was solved by increasing absorber tube diameter. The concentrating flux distribution on the absorber surface was uniform but peak flux existed.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.767-770
• /
• 1999

The carbonation process is affected both by the concrete material properties such as W/C ratio, types of cement and aggregated, admixture characteristics and the environmental factors such as CO2 concentration, temperature, humidity. Based on results of preliminary research on carbonation, this study is to propose a carbonation prediction model by taking into account of prediction model by taking into account of CO2 concentration and W/C ratio among major factors affecting the carbonation process.