• Nuclear Engineering and Technology
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• v.19 no.2
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• pp.99-106
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• 1987

Comparison study on the radiological effects by radionuclides from hypothetical 1,000MWe coal-fired power station and nuclear power plant is made. This paper describes the radiological effects only for gaseous effluents released in normal operation. Source terms for coal-fired Power station are quoted from foreign data and those for nuclear power plant are calculated for reference power plant. Gaussian plume model is used to assess atmospheric dispersion of radioactive effluents based on one year meteorological data of Kori site and individual doses are calculated at the maximum X/Q point. Doses from nuclear power plant are slightly more than those from coal-fred power plant. In the case of coal-fired power plant, doses by ingestion of contaminated vegetation are 73.5% of total doses.

• Journal of Soil and Groundwater Environment
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• v.21 no.1
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• pp.40-48
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• 2016

A siderophore-producing bacterium (i.e., Pseudomonas aeruginosa) capable of chelating Fe³⁺ from its mineral form (i.e., iron oxides) was used to enhance As uptake by plants. Since As in soil is mainly associated with iron oxides, siderophore can play an important role in As mobilization through the dissolution of As-bearing iron oxides. A series of pot experiment using Pteris cretica showed that As removal by P. cretica with siderophore-producing bacteria addition increased more than three times compared to that without bacteria addition. Competition between indigenous bacteria and introduced bacteria (i.e., P. aeruginosa) was also observed, but such competition seemed not to be significant. This study suggests that enhanced-phytoremediation by siderophore-producing bacteria addition could be a visible option for longterm As removal in the forest area at the former Janghang smelter site.

• The Journal of Korea Robotics Society
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• v.16 no.3
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• pp.223-231
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• 2021

In this paper describes the research and development of a pipe robot for pipe rehabilitation construction of old water pipes. After the water supply pipe construction, the pipe is leaking, damaged, and aging due to corrosion. Eventually, resistance to the flow of water in lower supply efficiency and contaminated water such as rusty water, finally in various consumer complaints. In order to solve this problem, rehabilitation construction robot technology is required to secure the construction quality of pipe rehabilitation construction and restore the function of the initial construction period. The developed pipe rehabilitation construction robot required a hydraulic actuator for high traction and was equipped with a small hydraulic supply device. In addition, we have developed a hydraulic cylinder and a link system that supports the pipe inner diameter to develop a single pipe robot corresponding to 500 to 800mm pipe diameter. The analysis and experimental verification of the driving performance and unit function of the developed pipe reconstruction robot are explained, and the result of the integrated performance test of the pipe reconstruction robot at the water supply pipe network site is explained.

• Progress in Superconductivity and Cryogenics
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• v.24 no.3
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• pp.19-23
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• 2022

We have been developing a magnetic separation device that can be used in low magnetic fields for paramagnetic materials. Magnetic separation of paramagnetic particles with a small particle size is desired for volume reduction of contaminated soil in Fukushima or separation of iron scale from water supply system in power plants. However, the implementation of the system has been difficult due to the needed magnetic fields is high for paramagnetic materials. This is because there was a problem in installing such a magnet in the site. Therefore, we have developed a magnetic separation system that combines a selection tube and magnetic separation that can separate small sized paramagnetic particles in a low magnetic field. The selection tube is a technique for classifying the suspended particles by utilizing the phenomenon that the suspended particles come to rest when the gravity acting on the particles and the drag force are balanced when the suspension is flowed upward. In the balanced condition, they can be captured with even small magnetic forces. In this study, we calculated the particle size of paramagnetic particles trapped in a selection tube in a high gradient magnetic field. As a result, the combination of the selection tube and HGMS (High Gradient Magnetic Separation-system) can separate small sized paramagnetic particles under low magnetic field with high efficiency, and this paper shows its potential application.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.3
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• pp.349-356
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• 2022

Nuclear power plant decommissioning generates significant concrete waste, which is slightly contaminated, and expected to be classified as clearance concrete waste. Clearance concrete waste is generally crushed into rubble at the site or a satellite treatment facility for practical disposal purposes. During the process, workers are exposed to radiation from the nuclides in concrete waste. The treatment processes consist of concrete cutting/crushing, transportation, and loading/unloading. Workers' radiation exposure during the process was systematically studied. A shielding package comprising a cylindrical and hexahedron structure was considered to reduce workers' radiation exposure, and improved the treatment process's efficiency. The shielding package's effect on workers' radiation exposure during the cutting and crushing process was also studied. The calculated annual radiation exposure of concrete treatment workers was below 1 mSv, which is the annual radiation exposure limit for members of the public. It was also found that workers involved in cutting and crushing were exposed the most.

• Microbiology and Biotechnology Letters
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• v.34 no.2
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• pp.166-173
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• 2006

This research has been performed to clarify the relationship between hydrogeochemistry and bacterial community structure in groundwater contaminated with landfill leachate. We collected and analyzed samples from 5 sites such as leachate (KSG1-12), treated leachate (KSG1-16), two contaminated groundwaters (KSG1-07 and KSG1-08) and non-contaminated groundwater (KSG1-13). pH was 8.83, 8.04, 6.87, 6.87 and 6.53 in order; redox potential (Eh) 108, 202, 47, 200 and 154 mV; electric conductivity (EC) 3710, 894, 1223, 559 and 169.9 $\mu$S/cm; suspended solids (SS) 86.45, 13.74, 4.18, 0.24 and 11.91 mg/L. In KSG01-12, the ion concentrations were higher especially in $Cl^-$ and $HCO_3^-$ than other sites. The concentrations of Fe, Mn and $SO_4^{2-}$ were higher In KSG1-07 than in KSG1-08, and vise versa in $NO_3^{2-}$. In the comparison of DGGE fingerprint patterns, the similarity was highest between KSG1-13 and KSG1-16 (57.2%), probably due to common properties like low or none contaminant concentrations. Otherwise KSG1-08 showed lowest similarities with KSG1-13 (25.8%) and KSG1-12 (27.6%), maybe because of the degree of contamination. The most dominant bacterial species in each site were involved in $\alpha$-Proteobacteria (55.6%) in KSG1-12, $\gamma$-Proteobacteria (50.0%) in KSG1-16, $\beta$-Proteobacteria (66.7%) in KSG1-07, $\gamma$-Proteobacteria (54.5%) in KSG1-08 and $\beta$-Proteobacteria (36.4%) in KSG1-13. These results indicate that the microbial community structure might be changed according to the flow of leachate in grounderwater, implying changes in concentrations of pollutants, available electron accepters and/or other environmental conditions.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.31-39
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• 2002

Pollutants from industry, mining, agriculture, and other sources have contaminated sediments in many surface water bodies. Sediment contamination poses a severe threat to human health and environment because many toxic contaminants that are barely detectable in the water column can accumulate in sediments at much higher levels. The purpose of this study was to make optimal treatment and disposal plan o( sediment for water quality improvement in small-scale resevoir based on an evaluation of degree of contamination. The degree of contamination were investigated for 23 samples of 9 site at different depth of sediment in small-scale J river. Results for analysis of contaminated sediments were observed that copper concentration of 4 samples were higher than the regulation of hazardous waste (3 mg/L) and that of all samples were exceeded soil pollution warning levels for agricultural areas. Lead and mercury concentration of all samples were detected below both regulations. Necessary of sediment dredge was evaluated for organic matter and nutrient through standard levels of Paldang lake and the lower Han river in Korea and Tokyo bay and Yokohama bay in Japan. The degree of contamination for organic matter and nutrient was not serious. Compared standard levels of Japan, America, and Canada for heavy metal, contaminated sediment was concluded as lowest effect level or limit of tolerance level because standard levels of America and Canada was established worst effect of benthic organisms. The optimal treatment method of sediment contained heavy metal was cement-based solidification/stabilization to prevent heavy metal leaching.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.296-303
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• 2010

Chromium as a constituent of rocks occurs naturally in the environment in varying concentrations. However, the human activity has changed the geochemical cycle of chromium in the environment and has caused the chromium accumulation in soils. Korean soils revealed a wide range of chromium contents depending on parent material and land use. The total chromium contents of volcanic ash soils in Jeju, which were determined using $HNO_3$ + $HClO_4$ + HF, ranged from 434 to 1,164 mg $kg^{-1}$. The 'ecological' total chromium contents extracted using conc. HCl + conc. $HNO_3$ (aqua regia) in the same soils varied in a lower range of 50-189 mg $kg^{-1}$ (averaged percentage of aqua regia contents in $HNO_3$ + $HClO_4$ + HF contents: 14.9%). Serpentine soils in Andong showed a 'ecological' total chromium content of 309 mg $kg^{-1}$ and against it granitic soils in Andong only 20 mg $kg^{-1}$. In uncontaminated forest soils of Korea, the 'ecological' total chromium contents varied from 4.89 to 106 mg $kg^{-1}$ and the soluble chromium contents determined using 0.1 M HCl ranged from 0.01 to 0.64 mg $kg^{-1}$ (averaged percentage of 0.1 M HCl contents in aqua regia contents: 0.4%). Arable lands contained more soluble chromium than reported in forest soils (averaged soluble chromium: 0.36 and 0.09 mg $kg^{-1}$, respectively). In particular, the soluble chromium contents in greenhouse, orchard and upland soils were higher than in contaminated soils near mine and industrial site (maximum contents: greenhouse 15.3 mg $kg^{-1}$; upland 12.1 mg $kg^{-1}$; orchard 8.29 mg $kg^{-1}$; mine site 4.76 mg $kg^{-1}$; industrial site 2.80 mg $kg^{-1}$). On the basis of these results a accumulation of chromium in some specific arable lands can be assumed, probably by long-continued applications of fertilizers or soil amendments containing chromium. In Korean Enforcement Decree of the Soil Environment Conservation Act soil standards for total chromium do not exist yet.

• Journal of the Korean GEO-environmental Society
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• v.15 no.8
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• pp.5-11
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• 2014

In this study, chemical analysis and ecotoxicity tests of leachate from disposal site for foot-and-mouth disease carcasses (FMD leachate) were conducted to collect fundamental data that will be used to develop environmental risk assessment tools for FMD leachate. For chemical analysis, concentration of $Cl^-$, $NH{_4}{^+}-N$, Korea standard method indicators for detection of leachate released from animal carcasses burial site into groundwater and NRN (Ninhydrin-Reactive Nitrogens), a newly suggested screening test indicator to detect groundwater contamination by FMD leachate, were assessed. For ecotoxicity tests, luminescent bacteria (V. fischeri), micro-algae (P. subcapitata) and water flea (D. magna) were selected as test species. Correlation analysis between the concentration of $Cl^-$, $NH{_4}{^+}-N$, NRN and the toxicity to V. fischeri was performed to identify the better indicators to monitor FMD leachate contamination. From regression analysis, the concentration of the indicators in FMD leachate contaminated sample that induced halfmaximal toxic effect to V. fischeri was evaluated. Results obtained from this study can be applied to assess the risk by FMD leachate and to establish the guideline to manage risk in relation to FMD leachate.

• Korean Journal of Environmental Agriculture
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• v.1 no.2
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• pp.105-115
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• 1982

Environmental samples contaminated with elemental sulfur(waters 22, sediments 20, crucian carps 19) collected from Soho Lake during the period of Sep. 1981 to Apr. 1982 were analyzed for polychlorinated biphenyls(PCBs) and organochlorine insecticides by GLC-ECD. Elemental sulfur was found to interfere in the residue analysis of environmental samples and the sulfur was eliminated, prior to analysis, with copper powder. PCBs residues in Soho lake were temporarily characterized as Aroclor 1254 and were analyzed at minimum detectable quantity of 0.04 ng by derivatizing PCBs to decachlorobiphenyl(DCB). PCBs were positively detected in all samples and its residue levels in waters, sediments, and crucian carps were $0.015{\sim}0.15$ ppb, $0.038{\sim}0.088$ ppm and 0.091 ppm, respectively. The residue levels of PCBs in all samples but sediments at central and outlet site of the lake were higher than those of total p,p'-DDT. The residue levels of PCBs in waters varied with inlets, i.e. those at right inlet site were three times of those at left inlet site. The main source of PCBs residues in the environmental samples of Soho Lake was not evident by present work.