• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.217-228
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• 2000

Circulating Fluidized Bed Combustor(CFBC) has been used for the incineration of waste sewage sludge and for the power generation. In this study hydrodynamic characteristics of two phase flow have been studied in a riser section of CFBC. A lab-scale riser is designed and SiC (Geldart type B) is used for solid particles. Experiments are performed by controlling the fluidization parameters including superficial velocity and secondary air to primary air ratio for determination of solid holdup profiles in the riser. Superficial velocities of each fluidization regime are well agreed with results predicted by a theoretical model. The results show that the axial solid holdup distributions calculated by measuring differential static pressures in the riser are found to show a basic profile described by a simple exponential function. Our flow regime during experiments mainly belongs to fast fluidization regime for particle size of 300${\mu}m$. As the SA/PA ratio increases, solid holdup in the lower dense region of the riser increases.

• Journal of the Korean Professional Engineers Association
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• v.18 no.2
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• pp.6-15
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• 1985

A new process disregraded the H$_2$SO$_4$ treatment process heretofore in use, was developed and substituted for mineral base engine used oil of homemade SAE-30 grade H.V.I., which was used covering 4,500km, as samples, and the following results in research, was obtained. (1) A good quality of rerefinded base oil was obtained through roughly a course of developed processes of vacuum distillation process, solvent extraction process, neutralization treatment process and clay treatment process. (2) Through vacuum distillation process, the size of fine grains of insoluble colloid carbon that is, colloid carbon which was produced by burning of internal combustion engine oil and fuel, could be brought up and precipitated (3) The insoluble matters and admixtures could be easily dispersed and dissolved by mixing and extracting solvent disregarded the H$_2$SO$_4$ treatment process heretofore in use (4) waste matter heretofore called acid sludge in consequence of the process, did not appear at all. accordingly, the environmental pollution could be removed. (5) The troubles of corrosion to copper strip which was faults of the usual used oil refined products and peculiar offensive odor of the rerefined oil, could be solved through the neutralization process. (6) The yield of rerefined oil obtained through a course of processes was over 86 percent, and it is of practical use, not to speak of commercial value.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.173-182
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• 1999

Internally Circulating Fluidized Bed Combustor(ICFBC) has been used for the incineration of waste sewage sludge. In this study hydrodynamic characteristics of two phase flow have been studied in a riser section of ICFBC. A lab-scale riser(l/5 scale of pilot plant) is designed and SiC (Geldart type B) is used for solid particles. Experiments are performed by controlling the fluidization parameters including superficial velocity, particle diameter and secondary air to primary air ratio for determination of solid holdup profiles in the riser. Our flow regime during experiments mainly belongs to the onset of turbulent regime(for d_{p}:300{\mu}m) and fast fluidization regime(for d_{p}:100{\mu}m). Superficial velocities of each regime are well agreed with results obtained by other researches. The results show that the axial solid holdup distributions calculated by measuring differential static pressures in the riser are found to show a basic profile described by a simple exponential function. As the particle size decreases, solid holdup along the riser is more uniformly distributed. To prove these experimental results, numerical calculations are being performed.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.3
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• pp.112-118
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• 2004

Laying hens' excrement from eating food wastes was mixed with paper mill sludge, aged for 21 days and then provided to the juvenile earthworms(Eisenia fetida) for 10 weeks. Biomass of earthworm population decreased by 5.7% of initially introduced population. Very few juvenile earthworms developed into the clitellates and clitellated earthworms could not produce cocoons at all, which was supposed to be caused by inhibition effects of salts in laying hens' excrement upon the sexual development of Eisenia fetida. But there was no significant effect on the survivorship of earthworm population.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.167-170
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• 2000

Proteolytic hydrolysis is one of the main enzymatic reaction of waste activated sludge (WAS) digestion. Pretense excreted from Bacillus stearothermophilus (ATCC 31197) showed optimum temperature of $75^{\circ}C$ for maxium heat stable proteolytic activity against azo casein. The dependency of $Ca^{2+}$, $Zn^{2+}$ on heat stability of proteolytic enzymes were measured with various concentrations. It was shown that $Ca^{2+}$ ion enhanced heat stability of these enzymes. Then thermophilic aerobic digestion (TAD) was performed using B. sterothermophilus with the addition of divalent ions. Performance of TAD process with ATCC 31197 activated by $Ca^{2+}$, $Zn^{2+}$ions in terms of dissolved organic carbon (DOC) concentration, extracellular protein concentration, and scanning electrion microscopy (SEM) analysis. The best result of protein reduction concentration in digestion test was obtained with the addition of 2 mM $Ca^{2+}$ ion.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.11
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• pp.544-550
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• 2002

This paper describes a strategy of a daily optimal operational scheduling on the industrial cogeneration system. The cogeneration system selected to establish the scheduling consists of three units and several auxiliary devices which include three auxiliary boilers, t재 waste boilers and three sludge incinerators. One unit generated electrical and thermal energy using the back pressure turbine. The other two units generate the energy using the extraction condensing turbine. Three auxiliary devices operate to supply energy to the loads with three units. The cogeneration system is able to supply enough the thermal energy to the thermal load, however it can not sufficiently supply the electric energy to the electrical load. Therefore the insufficient electric energy is compensated by buying electrical energy from utility. In this paper, the evolutionary algorithms was applied to establish the optimal scheduling for the cogeneration systems. Also the GUI System was developed using established mathematics medeling and evolutionary algorithms in order that non-experts are able to establish operational scheduling. This results revel that the proposed modeling and strategy can be effectively applied to cogeneration system for paper mill.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.10
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• pp.494-501
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• 2000

This paper describes a strategy of a daily optimal operational scheduling in cogeneration system for paper mill. The cogeneration system selected to establish the scheduling consists of three units and several auxiliary devices. One unit generates electrical and thermal energy using the back pressure turbine. The rest two units generate the energy using the extraction condensing turbine. Three auxiliary boilers, two waste boilers and three sludge incinerators operate to supply energy to the loads with three units. The cogeneration system is able to supply enough the thermal energy to the thermal load, however it can not sufficiently supply the electrical power to the electrical load. Therefore the insufficient electric energy is compensated by buying electrical energy from utility. When the operational scheduling is performed considering the environmental problem. This paper shows the simulation results for daily operational scheduling obtained using the evolutionary algorithm. This results reveal that the proposed modeling and strategy can be effectively applied to cogeneration system for paper mill.

• Journal of Microbiology and Biotechnology
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• v.20 no.3
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• pp.609-614
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• 2010

The effluent from anaerobic digestion contains organic nitrogen and phosphorus, which are both required for growth of Spirulina platensis. Effluent (20%) from the upflow anaerobic sludge blanket (UASB) from a pig farm, supplemented with 4.5 g/l sodium bicarbonate ($NaHCO_3$) and 0.2 g/l urea fertilizer (46:0:0, N:P:K), was found to be not only a suitable medium for the growth of Spirulina platensis but also a low-cost alternative. Cost calculation showed that this medium is 4.4 times cheaper than modifized Zarrouk's medium. The average productivities of a semi-continuous culture grown under outdoor conditions in a 6-1 scale and a 100-1 pilot scale were 19.9 $g/m^2/d$ and 12 $g/m^2/d$, respectively. In addition, the biomass of organisms grown in UASB effluent contained approximately 57.9% protein, 1.12% $\gamma$-linolenic acid, and 19.5% phycocyanin. The average rates of bicarbonate, total nitrogen, and phosphorus removal were 380 mg/l/d, 34 mg/l/d, and 4 mg/l/d, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.45-51
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• 2010

Electrical discharge drilling (ED-drilling) is a widespread machining method used to bore small holes with a high aspect ratio. This paper presents additional methods by which ED-drilling can improve machining speed, tool wear, and machined surface quality. Firstly, for high machining speed, and low tool wear, a new-type electrode that was ground on one side or both sides of the cylindrical electrodes was suggested to expel debris. The debris which is generated during the machining process can cause sludge deposition and secondary discharge problems: major reasons to decrease machining speed. This new-type electrode also reduced tool wear that was due to the decrease of unstable discharge in a machining gap by helping to expel waste water and debris from the gap. Secondly, to improve the machined surface roughness, an electrolyzation process was included after drilling. This process made the machined surface smooth by means of an electrochemical reaction between an electrode and a workpiece. In this study, the machining speed, electrode wear, and surface roughness were improved by the newtype electrode and the electrolytic process.

• Journal of Life Science
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• v.14 no.4
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• pp.577-581
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• 2004

Comamonas sp. AEBL-85 was isolated from microbial granules in an activated sludge process of long-term operated for the treatment of reactive azo dye, and characterized its capability to decolorize Reactive Black 5. The effects of adding carbon source and nitrogen source on the extent of decol-orization were analyzed to develop an optimal medium. The optimum initial pH and temperature wire 6.0 and 35$^{\circ}C$, respectively. Reactive Black 5 of 50 mg/l was readily decolorized up to 95% within 40 hr by Comamonas sp. AEBL-85.