• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.129-134
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• 2003

Anaerobic hydrogen production was executed using mixed anaerobic sludge. pH control (pH $5.5^{\sim}6.2)$ and heat treatment of anaerobic sluge at $92^{\circ}C$ was not effective for repressing the methane formation. The addition of $nitrate(500^{\sim}2,000\;mg/L\;KNO_3)$ made it possible to repress the methane formation, which resulted in the improvement of hydrogen production. By using SEM(Scanning Electron Microscope), less methane forming microbial with spagetti shape was observed when nitrate was supplied to anaerobic reactor.

• Journal of Korean Society on Water Environment
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• v.20 no.5
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• pp.534-538
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• 2004

Granulation characteristics have been studied with an aerobic sequencing batch reactor(SBR). Organic loading of 2.46kg COD/$m^3$/day followed by 4.14kg COD/$m^3$/day had been applied to the lab-scale SBR with a very short settling time during the operating cycle. The granulation proceeded to the diameter range of 3 to 5 mm with MLSS concentration of 12,000mg/L at 45th days of operation while COD removal efficiency remained almost consistent after the granule formation. It has been noticed that aerobic granulation under the higher loading with a very short settling time seemed to be due to the microbial selection of better flocculating species.

• Journal of Environmental Science International
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• v.10 no.6
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• pp.387-391
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• 2001

The hydroxyapatite(HAp) as a carrier the for ion exchange agent of $Ag^+$ions was prepared in semiconductor fabrication, The Ca/P molar ratio of the HAp was 1.65. The HAp is molded in shape of the antimcrobial ball and then sintered at 100$0^{\circ}C$ Ag-containing HAp(HAp-Ag) was prepared by incorporating $Ag^+$/ions in HAp crystals through an ion-exchange reaction in solutions containing 0.01M $AgNO_3$. The antimicrobial effect of HAp-Ag for bacteria such as Escherichial coli and Staphylococcus aureus has been Investigated. The concentrations of silver in the antimicrobial ball was determined by inductively coupled plasma and the amount of $Ag^+$ions was 9.0$\mu\textrm{g}$/g. The HAp-Ag exhibited excellent antimicrobial effect for bacteria such as E. coli and S. aureus. The bactericidal activity was considered to be caused by direct contact of bacteria with $Ag^+$ions in the HAp crystals. The HAp would likely to be possible as a carrier of antimicrobial metal ions such as Ag, Cu, and Zn by recycling of waste sludge in the semiconductor fabrication process.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.5
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• pp.401-410
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• 2002

Concerns for energy conservation, environmental pollution, and the fact that organic wastes account for a major portion of our waste materials, have created the interest of biogas, which usually contains about 60 to 70 percent methane, 30 to 40 percent carbon dioxide, and other gases, including ammonia, hydrogen sulfide, mercaptans and other noxious gases. Cyclone combustors are used for homing a wide range of fuels such as low calorific value gas, waste water, sludge. coal, etc. The 3-dimensional swirling flow, combustion and emission in a tangential inlet cyclone incinerator under different inlet conditions are simulated using a standard k-s turbulence model and ESCRS (Extended Simple Chemically-Reacting System) model. The commercial code Phoenics Ver.3.4 was used for the present work. The main parameters considered in this work are inlet velocity and air to fuel ratio. The results showed that the change of operating conditions had an influence on the shape and size of recirculation zones, mixture fraction and axial velocity which are important factors for combustion efficiency and emission behavior. The application of this kind of computer program seams to be promising as a potential tool for the optimum design of a cyclone combustor with low emission.

• 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 Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.1
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• pp.65-98
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• 2022

The nuclear legacy that remains in the United Kingdom (UK) is complex and diverse. Consisting of legacy ponds and silos, redundant reprocessing plants, research facilities, and non-standard or one-off reactor designs, the clean-up of this legacy is under the stewardship of the Nuclear Decommissioning Authority (NDA). Through a mix of prompt and delayed decommissioning strategies, the NDA has made great strides in dealing with the UK's nuclear legacy. Fuel debris and sludge removal from the legacy ponds and silos situated at Sellafield, as part of a prompt decommissioning strategy for the site, has enabled intolerable risks to be brought under control. Reactor defueling and waste retrievals across the Magnox fleet is enabling their transition to a period of care and maintenance; accelerated through the adopted 'Lead and Learn' approach. Bespoke decommissioning methods implemented by the NDA have also enabled the relevant site licence companies to tackle non-standard reactor designs and one-off wastes. Such approaches have potential to influence and shape nuclear decommissioning decision making activities globally, including in Korea.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.521-524
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• 2001

The anaerobic continuous reactor, which was filled with a sludge of anaerobic digestion from Sooyoung sewage treatment plant, was supplied with synthetic wastewater of various concentration. After changing to substrate concentration, 디 1is research indicated that attached biomass was kept constant after attachment 23 days. In SEM photographs. shape and structure of biofilm could be observed, but bacteria species and methanogens were not identified. A large number of methanogenic bacteria were showed on the surface of PE substratum by fluorescence under 480nm of radiation.

• Journal of the Korean GEO-environmental Society
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• v.11 no.7
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• pp.25-31
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• 2010

In this study, it was intended to suggest new cooling method that enables to improve the applicability and added value higher than existing slag by applying new cooling method(powder cooling slag) at the time discharging slag, which is produced from the ash melting system that the plasma torch is used for the first time in Korea. It is suggested the applicative direction in the development of future recycling process by discovering its nature of material and applicative possibility as earthwork material. The ashes produced after the sewage sludge discharged from Y city was incinerated by the fluidized bed method and was used as test materials. As result of XRF(X-Ray Flourescence Spectrometry) analysis, main ingredient of sewage sludge ashes was $SiO_2$(32%) besides CaO, $Al_2O_3$, $Fe_2O_3$, and so on. In addition, as result of XRD analysis, traditional diffuse pattern of glass could be found from granulated air-cooled slags, while a minor crystal phase could be observed from powder cooling slag, because the powder on the surface exists in the state not melted. From EDX(Energy Dispersive X-ray Spectroscopy) analysis, it is deemed that powder ingredient has no change before and after it is used as cooling medium, and accordingly it is thought that the powder can be produced as the material where the function is added if used in different shape.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.543-551
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• 2011

Steam generator tubes for nuclear power plants contain the local shape transitions on their inner or outer surface such as dent, bulge, over-expansion, eccentricity, deflection, and so on by the application of physical force during the tube manufacturing and steam generator assembling and by the sludge (that is, corrosion products) produced during the plant operation. The structural integrity of tubes will be degraded by generating the corrosive crack at that location. The profilometry using the traditional bobbin probes which are currently applied for measuring the profile change of tubes gives us basic information such as axial locations and average magnitudes of deformations. However, the three-dimensional quantitative evaluation on circumferential locations, distributional angle, and size of deformations will have to be conducted to understand the effects of residual stresses increased by local deformations on corrosive cracking of tubes. Steam generator tubes of Korean standard nuclear power plants expanded within their tube-sheets by the explosive expansion method and suffered from corrosive cracks in the early stage of power operation. Thus, local deformations of steam generator tubes at the top of tube-sheet were measured with an advanced rotating probe and a laser profiling system for the two cases where the tubes expanded by the explosive expansion method and hydraulic expansion. Also, the trends of eccentricity, deflection, and over-expansion of tubes were evaluated. The advanced eddy current profilometry was confirmed to provide accurate information of local deformations compared with laser profilometry.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.279-287
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• 2007

An ore of stone obtained from quarry lose its about 60% such as the muck and the stone-dust during the process of making the architectural block, the crushed aggregate and so on. A part of the muck is only reutilized for the crushed aggregate as road pavement materials, while the most of the muck in the shape of powder is mixed with water and then it is deposited in a sludge tank. The muck in the shape of powder is called the stone-dust. If the stone-dust is discharged and sprayed, an ecosystem will have terrible damage because the seepage of surface water, the flow of ground water and the movement of air are not occurred smoothly by packing the void of soils. As the Waste Management Law (2003) in Korea, the stone-dust is sorted out the industrial waste and the most of that is dumped in ground. Therefore, the establishments of an efficient recycling plan are necessary through the improvement of engineering properties of the stone-dust. To investigate the possibility of recycle and improvement for the stone-dust, the stone-dust and natural soils are sampled from six quarries in Korea. The various soil tests are performed by use of the mixed soils with the stone-dust content ratio. As the result of various soil tests, the recycle possibility of the stone-dust is analyzed as subbase layer materials of the roads.