• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.177-183
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• 2005

The effluent quality is directly affected by the separation of biological solids in a final clarifier because the majority of discharged $BOD_5$ and SS are virtually dependent on the results of biological solids in the sedimentation tank effluent. If a final clarifier is effectively designed and operated, the desired goal of clarification for wastewater can be achieved together with the cost reduction in the treatment of wastewater. To this end flow characteristics and the removal efficiency of SS are numerically investigated especially by the change of the inlet position and the installation of baffle to improve the performance of a rectangular final clarifier. The 2-D computer program developed in a rectangular coordinates has been successfully validated against experimental residence time distribution(RTD) curves obtained by tracing radio-isotope. The lowering of the inlet position weakens the density current and induces the settling of SS in the front zone of a clarifier. Thus the decreased traveling distance of the sludge increases the removal efficiency of SS in the effluent. The inlet baffle installed in the front region of clarifier prevents the short circuiting flow and induces to flow into the dense underflow, which eventually improves the effluent quality. In the case of lower inlet position, however, installation of baffle results in degradation of effluent quality. Consequently it is strongly recommended that in-depth numerical study be performed in advance for optimizing a clarifier design and retrofitting to improve effluent quality in a final clarifier.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.629-637
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• 2000

A two-phase anaerobic reactor with a submerged microfiltration system was tested for its ability to produce methane energy from organic wastewater. A membrane separation system with periodic backwashing with compressed air was submerged in the acidogenic reactor. The cartridge type of microfiltration (MF) membrane with pore size of $0.5{\mu}m$ (mixed esters of cellulose) was tested. An AUBF (Anaerobic Upflow Sludge Bed Filter: 1/2 packed with plastic media) was used for the methanogenic reactor. Soluble starch was used as a substrate. The COD removal was investigated for various organic loading with synthetic wastewater of 5,000 mg starch/L. When the hydraulic retention time (HRT) of the acidogenic reactor was changed from 10 to 4.5 days, the organic loading rate (OLR) varied from 0.5 to $1.0kg\;COD/m^3-day$. When the HRT of the methanogenic reactor was changed from 2.8 to 0.5 days, the OLR varied from 0.8 to $5.8kg\;COD/m^3-day$. The acid conversion rate of the acidogenic reactor was over 80% in the 4~5 days of HRT. The overall COD removal efficiency of the methanogenic reactor showed over 95% (effluent COD was below 300 mg/L) under the highly fluctuating organic loading condition. A two-phase anaerobic reactor showed an excellent acid conversion rate from organic wastewater due to the higher biomass concentration than the conventional system. A methanogenic reactor combined with sludge bed and filter, showed an efficient COD and SS removal.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.295-301
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• 2015

A theoretical analysis was carried out to examine the concentration behavior of methane from a biogas using a polysulfone membrane. After the governing equations were derived for the cocurrent flow mode in a membrane module, the coupled nonlinear differential equations were numerically solved with the Compaq Visual Fortran 6.6 software. At the typical operating condition of mole fraction of 0.7 in a feed stream, the mole fraction of methane in the retentate increased to 0.76 while the normalized retentate flow rate to the feed flow rate decreased from 1 to 0.79. When either the mole fraction of methane in a feed increased or the pressure of the feed stream increased, the methane mole fraction in the retentate increased. On the other hand, it was found that as either the membrane area decreased or the ratio of the permeate pressure to the feed pressure increased, the methane mole fraction in the retentate decreased. In case that the stage cut increased, the methane mole fraction in the retentate increased while the recovery of methane slightly decreased.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.317-327
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• 2012

The average specific cake resistance, the most important indicator for cake filtration and solid-liquid separation, is measured by filtration experiment. But the exact value is difficult to measure because of the other influences such as sedimentation during filtration. This study, a little more stable method named filtration-permeation is proposed for measuring average specific cake resistance. The filtration-permeation is composed of permeation of particle eliminated water through pre-formed cake by filtration. Using 1 wt% calcium carbonate suspension, the filtration-permeation experiments were performed for 8 kinds of filter media at the conditions of 0.5 atm and 0.2 atm, 1 and 3 sheets of filter media. At each specific condition, three to five times filtration-permeation were accomplished. As a result, stable permeation speed is measured. According to this experimental result, the characteristics of permeation and the effect of sedimentation are analyzed with Ruth's equation. The one way analysis of variance (one way ANOVA) is applied to the average specific cake resistances of filtration and permeation obtained with the selected three kinds of filter media. The average specific cake resistances between 0.5 atm and 0.2 atm by filtration do not distinguished, but those by permeation is perfectly distinguished. The experimental results during permeation have a very narrow distribution than that measured during filtration. The analysis of filtration experiments, it was verified that the resistance of filter medium by traditional method is of no significance. Finally, the migration of small particles through the medium composed of fiber glass at low pressure was studied.

• Resources Recycling
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• v.5 no.4
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• pp.25-31
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• 1996

The wastes ot l~mestone mines have been cause the extrar.ngance of the valuablz m e r a l s and destruction of the environment. Therefore, \\-c tied ta separation of calcite illid clay from the limestone mine wastes by rotntmg screen type separator made by ourselves in order to recyding such us a raw matcriala for cement maimfacture. CaO amtents in the separated coarse products increased from 37.36 wt% to 42+2 wt% at the condition ihat water content in wastes was lzss than 6wt%, the passing time of specimen in &amber was 15 semnds and the rotation speed was 6OLl qm. A process in order lo separate wastes effectively to having wide range aI part~dcs ize was cstablishcd and CaO contents of coarsc products through this process increased to 46.85 wt%. Tbis rcsult is insuEiicient to directly rcusing as a raw malerials for cement. However, it is supposed that coarse products would be able to be reuscd as a raw materials uf cement, if only it rs sclected dolomite in wastes, and really it may be possible in fields Othenvise, undcrsize products(less than 20 mm) would be able to recycling as a raw of cement bccause chcmicrl campasitions of thosc is kept almost constant v&cs on the overall process.

• Journal of Mushroom
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• v.9 no.3
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• pp.123-131
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• 2011

Winter mushroom was monitored to investigate the influence of storage temperature on its quality during the storage and distribution phase. In measuring its quality, the contents of saccharides were quantified with its fruiting bodies using HPLC. Although it has been known to be difficult to separate saccharide isomers, our results indicated that Grace Prevail carbohydrate ES $5{\mu}column$ was the best in the separation to analyze the saccharide out of six columns used in this study. In our results, xylose was the main component of saccharide in the fruiting body of winter mushroom(White line mushroom:47.68mg/g, brown line mushroom: 63.28mg/g). In long-term storage, the total amount of saccharide tended to increase, but trehalose content of the disaccharide decreased. In comparison with the paramount amount of lactose and myo-inositol contents in long-term storage at $4^{\circ}C$, lactose wasn't detected when stored at $-1^{\circ}C$.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.701-704
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• 2004

In this case, we would like to discuss about the single rooted deciduous mandibular first molar. The deciduous mandibular molar of a five years old boy was shown to have a single root, bilaterally. Ordinarily, the maxilary molars have three roots and the mandibular molars have two roots. However, when the hertwig's epithelial root sheath do not invaginate properly during tooth development, root fusion can occur from the absence of root separation. Molars with fused roots not only have unfavorable crown to root ratio, but also according to many reports, have higher probability of having multiple congenitally missing teeth or dens invaginatus in the maxillary incisors, consequently requiring preventive dental treatment In addition, disorders such as ectodermal dysplasia, syndactyly, clinodactyly, bluish sclera can also be related to this condition. Root fusion is known to be of autosomal recessive inheritance. Up to date, single rooted molars have been reported several times in permanent dentitions but hardly in deciduous dentition, which is the motive for this paper.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.19 no.1
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• pp.20-30
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• 1993

Liquid Chromatographic behavior of Pd(II) in Isonitosoethylacetoacetate imine IEAA-NR: R=H, CH3, C2H5, n-C3H7, n-C4H9, C6H5-CH2) Chelates were investigated by reversed phase high performance 1iquid chromatography on Micropak MCH-5 Column using Methanol /water as mobile phase. The optimum condition for the separation of Pd-Isonitrosoethylacetoacetate imine chelates were examined with respect to the flow rate, mobile phase strength. It was found that Pd(IEAA-NR)2 chelates were eluted in an acceptable range of the capacity factor value (0 $\leq$ log k' $\leq$ 1), The dependence of the logarithm of capacity factor(k') on the volume fraction of water in mixture with in the binary mobile phase was examined. Also, the dependence of k'on the liquid-liquid extraction distribution constant in methanol-water / n-alkane extraction system was on system was invert tigated for Pd(IEAA-NR)2. Both kinds of dependence are linear, which suggests that the retention of the electroneutral metal chelates be largely due to the solvophobic effect.

• Membrane Journal
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• v.15 no.4
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• pp.310-319
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• 2005

This paper describes the preliminary study on the development of multi-stage membrane demonstration plant for removal of carbon dioxide from flue gas stream being emitted from LNG boiler in thermal power generation plant. The prerequisite requirement is to design and develop the membrane process producing a $99\%\;CO_2$ with $90\%$ recovery from LNG flue gas of 1,000 $Nm^3$/day. Asymmetric polyethersulfone hollow fiber membranes and membrane modules developed in this laboratory[1] were used in this study. Using the permeation data for the hollow fiber membranes, modelling on the membrane module and multi-stage membrane process was done to meet the requirement condition of the process design. The effects of the operating pressure of feed and permeate side and feed concentration on $CO_2$ purity and recovery were investigated experimentally with the developed hollow fiber modules. These experimental results matched well with theoretical modelling results.

• Membrane Journal
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• v.21 no.1
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• pp.55-61
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• 2011

$BaCo_{0.7}Fe_{0.22}Nb_{0.08}O_{3-{\delta}}$ oxide was synthesized by solid state reaction method. Dense ceramic membrane was prepared using as-prepared powder by pressing and sintering at $1,200^{\circ}C$. XRD result of membrane showed single perovskite structure. Leakage and oxygen permeation test were conducted on the membrane sealed by glass ring as a sealing material. The oxygen permeation flux increased with increasing temperature and pressure difference and maximum oxygen permeation flux was $2.3mL/min{\cdot}cm^2$ at $950^{\circ}C$ with $Po_2$ = 0.63 atm of oxygen partial pressure. The oxygen permeation in the condition of air with $CO_2$ (300 ppm) as feed stream decreased as much as only maximum 2.9% in comparison with air feed stream. It indicated $BaCo_{0.7}Fe_{0.22}Nb_{0.08}O_{3-{\delta}}$ membrane is more stable than another membrane for carbon dioxide.