• Journal of Radiation Protection and Research
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• v.10 no.1
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• pp.50-63
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• 1985

A derivation of new release limit, named Derived Release Limit(DRL), into the atomsphere from a reference nuclear power plant has been performed on the basis of the new system of dose limitation recommended by the ICRP, instead of the (MPC)a limit which has been currently used until now as a general standard for radioactive effluents in Korea. In DRL Calculation, a Concentration Factor Method was applied, in which the concentrations of long-term routinely released radionuclides were in equilibrium with dose in environment under the steady state condition. The analytical model used in the exposure pathway analysis was the one which has been suggested by the USNRC and the exposure limits applied in this analysis were those recommended by the USEPA lately. In the exposure pathway analysis, all of the pathways are not considered and some may be excluded either because they are not applicable or their contribution to the exposure is insignificant compared with other pathways. In case, the environmental model developed in this study was applied to the Kori nuclear power plant as the reference power plant, the highest DRL value was calculated to be as $9.10{\times}10^6Ci/yr$ for Kr-85 in external whole body exposure from the semi-infinite radioactive cloud, while the lowest DRL value was observed 3.64Ci/yr for Co-60 in external whole body exposure from the contaminated ground, by the radioactive particulates. The most critical exposure pathway to an individual in the unrestricted area of interest (Kilchun-Ri, 1.3 km to the north of the release point) seems to be the exposure pathway from the contaminated ground and the most critical radionuclide in all pathways appears to be Co-60 in the same pathway. When comparing the actual release rate from KNU-l in 1982 with the DRL's obtained here the release of radionuclides from KNU-1 were much lower than the DRL's and it could be conclued that the exposure to an individual had been kept below the exposure limits recommended by the USEPA.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.81-92
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• 2001

According to analyses of high-resolution seismic profiles (air gun, sparker, and SBP) and a deep-drill core(YSDP 105) in the mid-eastern Yellow Sea, stratigraphic and geoacoustic models have been established and seismo-acoustic modeling has been fulfilled using ray tracing of finite element method. Stratigraphic model reflects seismo-, litho-, and chrono-stratigraphic sequences formed under a significant influence of Quaternary glacio-eustatic sea-level fluctuations. Each sequence consists of terrestrial to very-shallow-marine coarse-grained lowstand systems tract and tidal fine-grained transgressive to highstand systems tract. Based on mean grain-size data (121 samples) of the drill core, bulk density and P-wave velocity of depositional units have been inferred and extrapolated down to a depth of the recovery using the Hamilton's regression equations. As goo-acoustic parameters, the 121 pairs of bulk density and P-wave velocity have been averaged on each unit of the stratigraphic model. As a result of computer ray-tracing simulation of the subsurface strata, we have found that there are complex ray paths and many acoustic-shadow zones owing to the presence of irregular layer boundaries and low-velocity layers.

• Microbiology and Biotechnology Letters
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• v.17 no.2
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• pp.100-108
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• 1989

Thirty-six aromatic compound biodegraders; 10 strains for benzoate, 10 for salicylate, 6 for m-toluate, and 10 for DL-camphor were isolated and taxonomically characterized. A mutant Pseudomonas strain, Ben 6-2, derived from Ben 6 revealed remarkably improved ability to metabolize benzoate. Thus enhancement of the average substrate removal rate from 5.2 to 11.0mg/$\ell$/ hr was attained by the mutant. Both of strains Sal 7 and Tol 2, degraders of salicylate and m-toluate respectively, were classified as Pseudomonas sup. Both strains were found to be extremely effective in metabolizing each aromatic substrates. The average substrate degradation rates in minimal salt media containing 2,200mg/$\ell$ of the substrate were calculated to be 40.1 mg/$\ell$/ hr for strain Sal 7 and 33.0mg/$\ell$/ hr for Tol 2. Cam 10, a camphor degrading strain was demonstrated to be capable of mineralizing benzoate, phenol, toluene, octane, cyclohexane and xylene as well as camphor. Strain 1040 isolated from Cam 10 after repented adaptation to 1,000 mg/$\ell$ m-toluate gained the ability to utilize toluate as a sole carbon source. The mutant Brew actively at the expense of a mixture of car-bon sources; camphor, m-toluate, benzoate and phenol (each: 200 mg/$\ell$) and utilized the substances in the preferential order of camphor, phenol, benzoate, and m-toluate. Among the biodegraders examined Cam 1040 and Tol 2 were detected to harbor plasmid. The plasmid from Cam 1001 was determined to be about 98kb, and evidenced to encode the enzyme(s) for the degradation of camphor. For the further diversification of the metabolic potentials of Cam 1040, the NAH 2 plasmid of Pseudomonas putida NCIB 9816 was transferred to Cam 1040 by conjugation. The exconjugant obtained, Cam 1043, proved to gain an additional ability to metabolize salicylate and naphthalene.

• Korean Journal of Ecology and Environment
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• v.36 no.1 s.102
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• pp.83-94
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• 2003

Concentrated releases of zinc into water usually results from discharges associated with industrial purpose. The released zinc into soil is corroded and released into water. In aquatic environment, exess zinc is toxic to the organisms and causes the growth inhibition and malformation of them as a heavy metal. In this study, excess zinc toxicity was tested by FETAX (frog embryo teratogenetic assay with Xenopus)as in vivo system. Xenopus embryos at st.9 were exposed to $100{\sim}900\;{\mu}M$ of zinc for 7 days and 81% of individuals were survived in 100 ${\mu}M$, and 25% were survived in 1000M of zinc solution. In external malformations, swelled belly and intestinal dysplasia were common, and all of tested individuals showed these malformations in 200 ${\mu}M$ or higher concentration of zinc. In 400 ${\mu}M$ or higher concentration, all of tested tadpoles showed faded heart. Also, hypo-pigmentation, lens hernia and loose digestive track were very frequently found in 100 ${\mu}M$ of zinc. The histological study with paraffin section of zinc treated tadpoles showed following abnormalities; regeneration of photoreceptor on retina, reduced vitreous chamber in eye, reduction of red blood cells in heart, abnormal liver, swelling of pronephric cell, muscle dysplasia and palatal papilloma. These abnormalities may be caused by the degeneration of mitochondria, inhibition of cell adhesion, and the formation of leghemoglobin by zinc due to the substitution of $Ca^{2+}$ by $Zn^{2+}$. The body length was reduced due to the excess zinc. From a statistical result, body lengths of 300 ${\mu}M$ or higher concentrative g개ups was significantly reduced comparing that of control group. Recently, many spontaneous malformations and reduction of amphibians are reported, From the results of present study, excess zinc mi호t be a factor of amphibian reduction, and the control of zinc discharges is very important.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.7
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• pp.445-453
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• 2012

An investigation for removal of 1-indanone (1-ID), which were commonly produced from the biological and/or chemical treatment and natural weathering of the PAHs-contaminated soils, via oxidative transformation mediated by birnessite in the presence of various phenolic mediators is described. This study also examines the potential effect of the natural occurring substance humic acid (HA) on the oxidative transformation. The experiment was carried out in aqueous phase as a batch test (10 mg/L 1-ID, 0.3 mM phenolic mediators, $1.0g/L\;{\delta}-MnO_2$, at pH 5). All of the 11 tested phenoilic mediators belong to the group of natural occurring phenols and are widely used as model constituents of humic substances. From the results of HPLC analysis, it is demonstrated that 1-ID was not reactive to birnessite itself, but it can be effectively removed in birnessite-mediated cross coupling reactions in the presence of the phenolic mediators. The percent removals of 1-ID after 2 day incubation were ranged from 9.2 to 71.2% depending on the phenolic mediators applied. The initial rate constant ($K_{int}$, $hr^{-1}$) values for the 1-ID removals obtained from the pseudo-first-order kinetic plots also widely ranged from 0.18 to 15.0. Results of the correlative analysis between the removal efficiencies and structural characteristics of phenolic mediators indicate that the transformation of the 1-ID was considerably enhanced by the addition of electron-donating substituents (e.g., -OH, $-OCH_3$) at the benzne ring, and much less enhanced by the addition of electron-withdrawing substituents (e.g., -COOH, -CHO). The presence of HA showed that removal efficiencies of 1-ID in the birnessite-phenolic mediator systems decreased with increasing HA concentrations. However at low concentration of HA (< 2 mg/L), it caused some enhancement in the removals of 1-ID as compared to the control.