• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.719-726
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• 2016

The problem of separation of isotopes in a concurrent gas centrifuge is solved analytically for an arbitrary binary mixture of isotopes. The separative power of the optimised concurrent gas centrifuges for the uranium isotopes equals to ${\delta}U=12.7(V/700m/s)^2(300K/T)(L/1m)kg{\cdot}SWU/yr$, where L and V are the length and linear velocity of the rotor of the gas centrifuge and T is the temperature. This equation agrees well with the empirically determined separative power of optimised counter-current gas centrifuges.

• Nuclear Engineering and Technology
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• v.13 no.3
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• pp.168-175
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• 1981

• Nuclear Engineering and Technology
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• v.14 no.2
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• pp.78-85
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• 1982

The steady-state rotation of plasma centrifuge is theoretically analyzed to understand the physics of rotating plasmas and its feasibility for isotope separation. The centrifuge system under consideration consists of an annular gap between coaxial cylindrical anode and cathode in the presence of an externally-applied axial magnetic field. A problem for coupled partial differential equations describing centrifuge fields is formulated on the basis of the magnetohydrodynamic equations. Two-dimensional solutions are found analytically in the form of Fourier-Bessel series. The current density and velocity distributions are discussed in terms of the Hartmann number and the geometrical parameter of the system. At typical conditions, rotational speeds of the plasma up to the order of 10$^4$m/sec are achievable, and increase either with increasing Hartmann number, or with increasing ratio of the axial length to the inner radius of the cylinder. In view of much higher speeds of rotation which can be achieved in plasma centrifuge, it is expected that its efficiency is superior to mechanically driven gas centrifuges.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.2_1
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• pp.169-176
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• 2022

Prognostics and health management (PHM) is recently converging throughout the industry, one of the trending issue is to detect abnormal conditions at decanter centrifuge during water treatment facilities. Wastewater treatment operation produces corrosive gas which results failures on attached sensors. This scenario causes frequent sensor replacement and requires highly qualified manager's visual inspection while replacing important parts such as bearings and screws. In this paper, we propose anomaly detection by measuring the vibration of the decanter centrifuge based on the video camera images. Measuring the vibration of the screw decanter by applying the optical flow technique, the amount of movement change of the corresponding pixel is measured and fed into the LST M model. As a result, it is possible to detect the normal/warning/dangerous state based on LSTM classification. In the future work, we aim to gather more abnormal data in order to increase the further accuracy so that it can be utilized in the field of industry.

• Journal of Environmental Science International
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• v.5 no.5
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• pp.555-560
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• 1996

The toxic substances (endotoxins) from the bacterial cell walls were extracted by using incubator, centrifuge, UV-Vis spectrophotometer, and their fatty acid compositions were analyzed by Gas Chromatography. The lethal toxicities and pyrogenic activities of toxic substances were tested and the results were compared each other. The results of fatty acid analyses showed that the major fatty acid of the toxic substance was tetradecanoic acid for Vibrio vulnificus, dodecanoic acid for Escherichia coli, and decanoic acid for Salmonella typhimurium. These three fatty acids were the main fatty acids ofr three toxic substances (more, than 70%). The unique points in the fatty acid compositions were that tetradecanoic acid was composed as important one (37.15%) for V. vulnificus and that the amount of hexadecanoic acid was very small (below 2%) for three toxic substances. The lethal toxicity in ICR mice of toxic substance from V. vulnificus (LD50 was 52.5 mg/kg) was similar to that of E. coli (56.5mg/kg), but weaker than that of S. typhimurium (37.5mg/kg). Toxic substance from V. vulnificus was more pyrogenic in rabbit than that from E. coli, but less than that from S. typhimurium.

• Nuclear Engineering and Technology
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• v.50 no.1
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• pp.126-131
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• 2018

As it is known, uranium enrichment is carried out on industrial scale by means of multistage separation facilities, i.e., separation cascades in which gas centrifuges (GCs) are connected in series and parallel. Design and construction of these facilities require significant investment. So, the problem of calculation and optimization of cascade working parameters is still relevant today. At the same time, in many cases, the minimum unit cost of a product is related to the cascade having the smallest possible number of separation elements/GCs. Also, in theoretical studies, it is often acceptable to apply as an efficiency criterion the minimum total flow to supply cascade stages instead of the abovementioned minimum unit cost or the number of separation elements. In this article, cascades with working parameter of a single GC changing from stage to stage are optimized by two of the abovementioned performance criteria and are compared. The results obtained allow us to make a conclusion about their differences.

• Parasites, Hosts and Diseases
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• v.38 no.3
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• pp.173-175
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• 2000

The present study examined postmetacercarial changes in the excysted metacercariae of Echinostoma caproni maintained in the defined medium Mixture 199 plus 20% calf serum for 7 days at $41^{\circ}C$. The gas phase was atmospheric air. Each culture was inoculated with 25 excysted metacerariae. Cultures were maintained upright in closed 15 ml plastic centrifuge tubes each containing 10 ml of medium plus 200 units of penicillin/ml and $200{\;}\mu\textrm{g}$ of streptomycin/ml. By 4 days in culture, most metacercariae had voided their excretory concretions. Organisms were clumped or solitary at the bottom of the cultures. Many organisms showed flaring of the oral collar and extension of both the collar and tegumentary spines. By 4 days in culture, posterior protuberances or bumps were noted on many of the organisms and some organisms showed abnormal vesicular growths or blebs at their posterior ends. Some mortality was noted in culture by day 5, but most organisms were still alive when the cultures were terminated on day 7.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.4
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• pp.544-547
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• 1999

The object of this study was to determine the influence of monensin and virginiamycin (VM) on in vitro ruminal fermentation of rice straw or ammoniated rice straw. Rumen fluid was collected from 4 wethers fed 200 g of concentrate supplement with 400 g of untreated (U) or ammoniated (A) rice straw once daily for 28 days. Mixed ruminal microorganisms were incubated in anaerobic media that contained 20% (vol/vol) ruminal fluid and 0.3 g of either U or A rice straw. Monensin and/or VM, dissolved in ethanol, were added in centrifuge tubes at final concentrations of 0, 15, 30, 15+15 and 30+30 ppm of culture fluid. The addition of monensin and VM combination to A rice straw fermentation decreased (p<0.05) the acetate to propionate ratio, total VFA and lactate production, but increased (p<0.05) pH. Total gas production tended to be decreased by the addition of monensin plus VM. Antimicrobial agents decreased $NH_3$ N concentration and dry matter digestibility.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.5
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• pp.828-836
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• 1987

The inclusion of thermophoresis in particle deposition studies has often been treated separately from deposition due to flow characteristics. Also previously reported experimental results on thermophoresis have been studied in the regions of relatively small temperature gradients. In this study, using real-time laser light reflectivity method, we measured the angular dependence of the deposition rates of particles of the cylindrical collector surface, which immerged in laminar flow of a hot gas suspension of small particles. And we extended the previous narrowband results of thermophoretic deposition rates to the regions of large temperature gradients between the hot gas stream and the collector surface. Based on the obtained data, the cylinder's forward stagnation-point region is considerably enriched in particle 'phase' density owing to the compressibility effect, which leads to locally enhanced deposition while the downstream region from the stagnation point inertial force acts in the opposite direction, which tends to centrifuge particles away from the wall, thus the local deposition rates by thermophoresis are reduced.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1123-1129
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• 2006

Pyrene of natural and anthropogenic sources is one of the toxic, mutagenic polycyclic aromatic hydrocarbons (PAHs) listed as priority pollutants. The objectives of this research are to break down pyrene by using ozonation, identify the intermediates and byproducts of pyrene, and test the biodegradability of intermediates and byproducts of pyrene in the aqueous phase. Since pyrene is non-polar, hexane was chosen as a solvent to effectively dissolve pyrene. Pyrene solutions were treated with ozone, as it has high oxidation capacity and electrophilic characteristic. After different ozonation pretreatment times (2, 3, and 10 minutes), intermediates of pyrene in the form of yellowish solid were collected from the hexane solution using a centrifuge. They were identified by gas chromatography/mass spectrometer (GC/MS). $BOD_5$, COD, and E-coli toxicity tests have been performed to assess the ozonation products.