• Journal of Soil and Groundwater Environment
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• v.9 no.2
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• pp.41-47
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• 2004

This research in the degradation of polychlorinated biphenyls(PCB) has focussed on the use of experimental enrichment cultures to obtain PCB-deading communities and identification of PCB-degrading bacteria accor야ng to pure culture. During 180 days, enrichment culture was performed to obtain PCB-degrading bacteria and initial concentration was injected 1.6 ppm,0.7 ppm, respectively. After 180 days of enrichment culture, PCBs was removed 80-87% and 57-71%. Biodegradation of PCBs was studied according to dominated PCB-degrading bacteria. Biodegraddation of PCBs was 80% in initial concentration of PCBs for 20days, enrichment cultured PCB-degrading bacteria was isolated by pure culture and it was verified to Pseudoxanthomonas sp.

• Microbiology and Biotechnology Letters
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• v.24 no.6
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• pp.647-651
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• 1996

The development of an enrichment method for the rapid and effective identification of Salmonella spp. in sewage or food was studied. As a growth factor for Salmonella, 10 mM cyclic adenosine monophosphate (cAMP) in trypticase soy broth with 0.6% yeast extract (TSBYE) increased cell number five-folds and 0.6% yeast extract in selenite broth increased cell number ten-folds of control. Bile salts in selenite broth was tested for the selection of S. enteritidis in a mixture with Staphylococcus aureus, Pseudomonas aeruginosa, Lactobacillus plantarum and Escherichia coli. The latter four strains were effectively inhibited at 0.1% bile salt. A two-step culture method was used to enrich Salmonella spp.; a primary-enrichment and secondary- enrichment culture. At a primary-enrichment step, selenite broth with 0.6% yeast extract and 10 mM cAMP was used, and at a secondary-enrichment step, 0.1% bile salt was additionally used. Culture times of a primary- enrichment and a secondary-enrichment step were 8 hr and 6 hr, respectively. In this procedure, cell number increased from 10$^{0.3}$ to 10$^{8.5}$ with inhibition of other strains within 14 hr. In the case of an initial cell concentrarion as low as 10$^{-2}$ cfu/ml, a cell number increased to 10$^{7}$ cfu/ml by using a 10 hr primary-enrichment and 6 hr secondary-enrichment procedure.

• Nuclear Engineering and Technology
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• v.47 no.5
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• pp.596-607
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• 2015

In this paper, we describe a computer program, iBEST (inverse Burnup ESTimator), that we developed to accurately estimate the burnup histories of spent nuclear fuels based on sample measurement data. The burnup history parameters include initial uranium enrichment, burnup, cooling time after discharge from reactor, and reactor type. The program uses algebraic equations derived using the simplified burnup chains of major actinides for initial estimations of burnup and uranium enrichment, and it uses the ORIGEN-S code to correct its initial estimations for improved accuracy. In addition, we newly developed a stable bisection method coupled with ORIGEN-S to correct burnup and enrichment values and implemented it in iBEST in order to fully take advantage of the new capabilities of ORIGEN-S for improving accuracy. The iBEST program was tested using several problems for verification and well-known realistic problems with measurement data from spent fuel samples from the Mihama-3 reactor for validation. The test results show that iBEST accurately estimates the burnup history parameters for the test problems and gives an acceptable level of accuracy for the realistic Mihama-3 problems.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.39.1-39.1
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• 2014

We present the results of our analysis of the RR Lyrae (RRL) variable stars detected in two transition-type dwarf galaxies (dTrans), ESO294-G010 and ESO410-G005 in the Sculptor group, which is known to be one of the closest neighboring galaxy groups to our Local Group. Using deep archival images from the Advanced Camera for Surveys (ACS) onboard the Hubble Space Telescope (HST), we have identified a sample of RR Lyrae candidates in both dTrans galaxies [219 RRab (RR0) and 13 RRc (RR1) variables in ESO294-G010; 225 RRab and 44 RRc stars in ESO410-G005]. The metallicities of the individual RRab stars are calculated via the period-amplitude-[Fe/H] relation derived by Alcock et al. This yields mean metallicities of <[Fe/H]>_{ESO294} = -1.77 +/- 0.03 and <[Fe/H]>_{ESO410} = -1.64+/- 0.03. The RRL metallicity distribution functions (MDFs) are investigated further via simple chemical evolution models; these reveal the relics of the early chemical enrichment processes for these two dTrans galaxies. In the case of both galaxies, the shapes of the RRL MDFs are well-described by pre-enrichment models. This suggests two possible channels for the early chemical evolution for these Sculptor group dTrans galaxies: 1) The ancient stellar populations of our target dwarf galaxies might have formed from the star forming gas which was already enriched through "prompt initial enrichment" or an "initial nucleosynthetic spike" from the very first massive stars, or 2) this pre-enrichment state might have been achieved by the end products from more evolved systems of their nearest neighbor, NGC 55.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.3
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• pp.303-313
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• 2023

Spent fuels (SFs) are stored in a storage pool after discharge from nuclear power plants. They can be transferred to for the further processes such as dry storage sites, processing plants, or disposal sites. One of important measures of SF is the burnup. Since the radioactivity of SF is strongly dependent on its burnup, the burnup of SF should be well estimated for the safe management, storage, and final disposal. Published papers about the methodology for the burnup estimation from the known activities of important radioactive sources are somewhat rare. In this study, we analyzed the dependency of the burnup on the important radiation source activities using ORIGEN-ARP, and suggested simple correlations that relate the burnup and the important source activities directly. A burnup estimation equation is suggested for PWR fuels relating burnup with total neutron source intensity (TNSI), initial enrichment, and cooling time. And three burnup estimation equations for major gamma sources, ¹³⁷Cs, ¹³⁴Cs, and ¹⁵⁴Eu are also suggested.

• Journal of The Korean Astronomical Society
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• v.15 no.1
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• pp.19-36
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• 1982

For ${\sim}240$ nearby stars their age and mass were determined and kinematic parameters determined for 362 stars, applying Woolley's three-dimensional potential. Metallicity and kinematic parameters of these stars were correlated with their age, suggesting the slow collapse ($t{\gtrsim}a$ few billion years) of the Galaxy and the initial rapid enrichment in metal abundance (${\Delta}Z{\approx}1/3Z_1$(present) for ${\sim}4{\times}10^8$ yrs). The late slow enrichment rate is given by $d(Z/Z_{\odot})/dt=5.9{\sim}7.0{\pm}3.4$ per Gyr.

• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.23-38
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• 1999

This study addresses the reference spent fuel and its characteristics for developing a geological repository concept. As a disposal capacity of the reference repository system to be developed, spent fuel inventories were projected based on the basis of the Nuclear Energy Plan of the Long-term National Power Program. The reference spent fuel encompassing a variability in characteristics of all existing and future spent fuels of interest was defined. Key parameters in the reference fuel screening processes were the nuclear and mechanical design parameters and the burnup histories for existing spent fuels as of 1996 and for future spent fuels with the more extended burnup the initial enrichment and its expected turnup. The selected reference fuel was characterized in terms of initial enrichment, bumup, dimension, gross weight and age. Also the isotopic composition and the radiological properties are quantitatively identified. This information provided in this study could be used as input for repository system development and performance assessment and applied in fuel material balance evaluation for the various types of back-end fuel cycle studies.

• Journal of The Korean Astronomical Society
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• v.24 no.1
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• pp.25-53
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• 1991

The evolution of the Galaxy is examined by the halo-disk model, using the time-dependent bimodal IMF and contraints such as cumulative metallicity distribution, differential metallicity distribution and PDMF of main sequence stars. The time scale of the Galactic halo formation is about 3Gyr during which the most of halo stars and metal abundance are formed and ${\sim}95%$ of the initial halo mass falls to the disk. The G-dwarf problem could be explained by the time-dependent bimodal IMF which is suppressed for low mass stars at the early phase (t < 1Gyr) of the disk evolution. However, the importance of this problem is much weakened by the Pagel's differential metallicity distribution which leads to less initial metal enrichment and many long-lived metal-poor stars with Z < $1/3Z_{\odot}$ The observational distribution of abundance ratios of C, N, O elements with respect to [Fe/H] could be reproduced by the halo-disk model, including the contribution of iron product by SNIs of intermediate mass stars. The initial enrichment of elements in the disk could be explained by the halo-disk model, resulting in the slight decrease and then the increase in the slopes of the [N/Fe]- and [C/Fe]-distributions with increasing [Fe/H] in the range of [Fe/H] < -1.

• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.169-174
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• 2004

The NOx emission characteristics with oxygen enrichment in nonpremixed counterflow and coflow jet flame of $CH_4$ fuel have been investigated numerically. A small amount of nitrogen is included in oxygen-enriched combustion, in order to consider the inevitable $N_2$ contamination by air infiltration. The results show that the initial increase of NO with increasing oxygen enrichment is due to increasing temperature and residence time, while its subsequent decrease above 75% oxygen is due to decreasing the consumption rate of nitrogen. When oxygen addition exceeds 30%, Thermal NO gradually becomes the dominant production pathway and Prompt NO becomes negative pathway for net NO production rate. It is also seen that Thermal NO plays an important role in NO reduction when strain rate increase in oxygen-enriched combustion. Finally, the results of EINOx with oxygen enrichment in coflow jet flame show the similar profile with those of conterflow flame. It is confirmed that, with leakage of 1% nitrogen in the oxidizer stream, the corresponding EINOx is eight times of that emitted from regular $CH_4$/Air flame.

• Journal of Dairy Science and Biotechnology
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• v.41 no.3
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• pp.103-112
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• 2023

This study aimed to assess the effectiveness of 10 different pre-enrichment methods using Real-Time polymerase chain reaction (PCR) in support of the FDA method. When the initial Cronobacter spp. (Enterobacter sakazakii) inoculation was 7.2 CFU/g, the Ct values were observed in the following order: 21.37 (Enterobacteriaceae enrichment [EE] broth), 21.95 (brain heart infusion [BHI]), 22.72 (tryptic soy broth [TSB]), 23.02 (violet red bile lactose [VRBL]), 22.31 (TSB-0.1% sodium pyruvate [SP]), 23.43 (distilled water [DW]), 24.34 (phosphate buffered saline [PBS]), 24.95 (nutrient broth [NB]), 25.82 (TSB-0.6% yeast extract [YE]), and 28.27 (violet red bile glucose [VRBG]). For an inoculation of 1.82% CFU/g of Cronobacter spp. (E. sakazakii), the Ct values were recorded in this sequence: 20.34 (EE broth), 22.16 (TSB-0.6% YE), 22.37 (BHI), 22.71 (VRBL), 22.88 (TSB), 23.01 (DW), 23.19 (NB), 23.79 (TSB-0.1% SP), 24.66 (VRBG), and 24.70 (PBS). Finally, when the inoculum of Cronobacter spp. (E. sakazakii) was 0.182 CFU/g, the Ct values followed this order: 21.93 (VRBL), 23.07 (TSB-0.6% YE), 23.31 (DW), 23.47 (PBS), 23.70 (BHI), 24.14 (TSB-0.1% SP), 25.14 (TSB), 29.00 (VRBG), 31.55 (EE broth), and were undetected in the case of NB. Consequently, these results indicate that there were no significant differences among the 10 different pre-enrichment broths. Future studies should focus on exploring pre-enrichment broths that can improve the limit of detection at very low Cronobacter spp. (E. sakazakii) concentrations and enhance the selective recovery of Cronobacter spp. (E. sakazakii) under acid, antibiotic, cold, and heat damage conditions.