• Journal of Korean Society on Water Environment
• /
• v.18 no.4
• /
• pp.435-440
• /
• 2002

A pilot scale SBR (effective volume, $20m^3$) for the treatment of piggery wastewater treatment was performed with three different kinds of wastewater; fermenter effluent, scraper type and slurry type. The react phase in SBR was performed by sub-cycle operation consisting of repeated short cycle of anoxic-aerobic step. The fermenter effluent was characterized by the rapid nitrification and $NO_X-N$ accumulation due to depletion of organic matter in wastewater. The scraper type wastewater showed appropriate nitrogen removal efficiency, however, a poor response capacity for high loading rate often resulted in increased nitrogen concentration in effluent. Moreover, severe P release was the most serious problem in scraper type wastewater. SBR treated slurry type wastewater with high nitrogen removal efficiency to satisfy effluent quality requirement. It was thought that high concentration of organic matter in slurry made it possible to uptake P during SBR operation, where P concentration of 140mgP/l was decreased to 8mgP/l. As results, SBR was suitable to treat slurry type wastewater which has been discharged to the ocean till now.

• Journal of Environmental Science International
• /
• v.4 no.5
• /
• pp.115-115
• /
• 1995

Reuse of industrial effluents through the cooling systems in a petrochemical complex was described. The partial oxidation of the effluents from the biological treatment plant was examined, using Fenton''s reagent as a pretreatment step prior to a next treatment of the effluents. Next tertiary treatment using fixed-film reactor resulted in marked reductions in COD and suspended solids. The continuous fixed-film process with Fenton oxidation pretreatment showed a 23% increase in the COD removal efficiency when compared to that without pretreatment of Fenton oxidation under the volumetric organic loading rate of 0.1 kg COD/m3/day. The Fenton oxidation treatment seemed to be a possible method for tertiary biological treatment to reduce the residual toxicity with the enhanced biodegradation of the effluents.

• Journal of Environmental Science International
• /
• v.4 no.5
• /
• pp.501-508
• /
• 1995

Reuse of industrial effluents through the cooling systems in a petrochemical complex was described. The partial oxidation of the effluents from the biological treatment plant was examined, using Fenton's reagent as a pretreatment step prior to a next treatment of the effluents. Next tertiary treatment using fixed-film reactor resulted in marked reductions in COD and suspended solids. The continuous fixed-film process with Fenton oxidation pretreatment showed a 23% increase in the COD removal efficiency when compared to that without pretreatment of Fenton oxidation under the volumetric organic loading rate of 0.1 kg COD/m3/day. The Fenton oxidation treatment seemed to be a possible method for tertiary biological treatment to reduce the residual toxicity with the enhanced biodegradation of the effluents.

• Transactions on Electrical and Electronic Materials
• /
• v.12 no.3
• /
• pp.119-122
• /
• 2011

A series of mesoporous silicalites was synthesized using different compositions of tetraethylorthosilicate and methyltriethoxysilane (MTES) as the silica source. Cetyltrimethylammonium bromide was used as the organic template. Their detailed pore structures were investigated by transmission electron microscopy, X-ray diffraction, and N2 adsorption method. The thermal properties of these silicalites were studied by thermogravimetric analysis. The increased amount of MTES destroyed mesoporous channels and reduced pore sizes from 3.4 nm to 2.8 nm in calcined silicalites. The calcined silicalite transformed completely into an amorphous state at 30% MTES loading. Methyl pending groups of MTES hindered the structural ordering of ≡Si-O- frameworks, resulting in an amorphous structure. This was caused by the insufficient formation of supramolecular assembly with the organic template. No capillary condensation step was found in MS 7/3 silicalite. The other capillary condensation steps shifted toward the lower relative pressure with increasing MTES content, indicating the reduction of pore sizes.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.4 no.3
• /
• pp.53-61
• /
• 1984

A nonlinear formulation of a beam finite element(NB6) on the total Lagrangian mode for the geometrically nonlinear analysis of two-dimensional elastic framed structures is presented. The NB6 beam element has been degenerated from the three-dimensional continuum by introducing the deep beam assumptions and consists of three reference nodes and three relative nodes. The element characteristics are derived by discretizing the beam equations of motion using the Galerkin weighted residual method and are reduced-integrated repeatedly for each loading step by the Newton-Raphson iteration techpique. Several numerical examples are given to demonstrate the accuracy and versatility of the proposed nonlinear NB6 beam element.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.7 s.94
• /
• pp.1700-1709
• /
• 1993

The stepped specimen which is subjected to step loading is modeled to study the initiation and growth of adiabatic shear band using explicit time integration finite element method. Three different clearance sizes are tested. The material model for the stepped specimen includes effects of strain hardening, strain rate hardening and thermal softening. It is found that the material inside the fully grown adiabatic shear band experiences three phase of deformation, (1) homogeneous deformation phase, (2) initiation/incubation phase, and (3) fast growth phase. The second phase of deformation is initiated after sudden shear stress drop which occurs at the same time regardless of the clearance size. The incubation time prior to fast growth phase increases, as the clearance size of the stepped specimen increases. Whereas, after incubation period, the growth rate of the adiabatic shear band decreases, as the clearance size decreases. It is also found that two adiabatic shear band may develop instead of one for the smaller clearance size.

• Geomechanics and Engineering
• /
• v.16 no.3
• /
• pp.309-320
• /
• 2018

In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.

• Journal of environmental and Sanitary engineering
• /
• v.13 no.1
• /
• pp.44-56
• /
• 1998

This study was performed to investigate the reaction characteristics of piggery wastewater for biological nutrient removal. The reaction characteristics were discussed the fraction of organics, the behavior of nitrogen, nitrification, denitrification, and the behavior of phosphorus. The fraction of readily biodegradable soluble COD was 11-12 percent. The ammonia nitrogen was removed via stripping, nitrification, autotrophic cell synthesis, and heterotrophic cell synthesis. The removal percents by each step were 12.1%, 68.9%, 15.0%, and 4.0%, respectively. Nitrification inhibition of piggery wastewater was found to occur at an influent volumetric loading rate over 0.2 NH$_{3}$-N kg/m$^{3}$/d. Denitrification rates were the highest in the raw wastewater and the lowest in the anaerobic effluent. The denitritation of piggery wastewater came out to be possible, and the rate of organic carbon consumption decreased about 10 percent. The phosphorus removed was released in the form of ortho-p in the aerobic fixed biofilm reactor, it was caused by autooxidation. The synthesis and release of phosphorus were related to the ORP and the boundary value for the phase change was about 170mV. In the synthesis phase, the phosphorus removal rate per COD removed was 0.023mgP$_{syn}$/mgCOD$_{rem}$. The phosphorus contents of the microorganism were 4.3-6.0% on a dry weight basis.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.8
• /
• pp.203-212
• /
• 1999

This paper describes a deadweight force standard machine with the weight change mechanism which can be used as a primary force standards at a national metrology institute. Since commercial deadweight force machine can generate forces by hanging weights to the weight supporter serially, force steps from deadweight force measuring devices of each having different capacity. In order to increase the force steps, we have specially designed a weight mechanism in which the machine can select the necessary weights and generate the load by hanging the selected weights to the weight supporter. The machine can generate 속 force of the range of 2 kN to 110 kN with force step of 1 kN. All weights have been accurately compensated and calibrated by a mass comparator and its standard uncertainty is less than 2.2 ${\times}\;10^{-6}$. The relative expanded uncertainty of the machine is 1.3 ${\times}\;10^{-5}$.

• Journal of Korean Society of Water and Wastewater
• /
• v.23 no.4
• /
• pp.431-438
• /
• 2009

The purpose of this study was to evaluate the performances of zero-valent iron (ZVI) combined SBR (Z-SBR) process in decolorization and organic removal of synthetic dye wastewater. The batch test for optimizing the operation parameters of ZVI column showed that the appropriate EBCT was around 11 min and the pH of the dye wastewater was below 7.0. During the step increase of influent color unit from 300 to 1,000cu, about 53 to 79% decolorization efficiency could be achieved in control SBR (C-SBR, without ZVI column), which resulted from destroying azo bond of synthetic dye in anaerobic condition. For the same influent color loading, Z-SBR showed always higher decolorization efficiency than C-SBR with an aid of ZVI reducing power. The TCOD concentration in Z-SBR effluent was 20-30mg/L lower than C-SBR effluent although the TCOD before and after ZVI column was nearly same. It means that breakdown of azo bond by ZVI reducing power could increase biodegradability of synthetic dye wastewater.