• Journal of the Korean Society of Radiology
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• v.14 no.6
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• pp.801-810
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• 2020

In this study, the health insurance application of PET and the change in the pay standard were examined, and the amount of health insurance use over the past 10 years was analyzed. Positron tomography was applied as health insurance in 2006, and after ¹⁸F-FDG was first applied as health insurance, positron tomography tests using various radioactive isotopes have been applied as health insurance. As of 2019, the number of positron emission tomography tests was 198,651 cases, and the treatment amount was about 88.3 billion won, and the number of tests according to general characteristics was higher in men than in women, and by age, the number of tests was the highest in 60s. The number of outpatient examinations was higher than that of inpatient examinations, and the number of examinations in tertiary hospitals(68.2%) was significantly higher than that of general hospitals and hospitals. As for the test site, torso test was the most common at 86.6%, and radioisotope was the most at 93.6% using ¹⁸F-FDG. The change in the use of PET for 10 years increased steadily from 2010 to 2014, but the amount of use decreased sharply afterwards as the recognition of asymptomatic long-term follow-up tests was deleted due to the government's change in health insurance application standards in 2014. As changes in health insurance standards have a great influence on changes in health insurance usage, continuous monitoring will be required in the future.

• Journal of the Korean Geographical Society
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• v.43 no.4
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• pp.477-494
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• 2008

Stable isotope analyses on lake or wetland sediments are useful to reconstruct paleoclimate. Organic and inorganic carbonates obtained from lake sediment are isotopically analyzed to get oxygen and carbon isotopic ratios. Oxygen isotope ratios can be used to quantitatively and qualitatively reconstruct paleo-temperature or humidity while carbon isotope ratios be used to reveal environmental changes around the lake or human impacts on the area. Peat mosses in peat bogs are nice samples for the carbon isotope analysis, which derives paleo-temperature and paleo-atmospheric $CO_2$ changes. In coastal area, the reconstruction of past sea-level is possible because terrestrial originated organic matter is carbon isotopically different from marine originated organic matter. Also, scientists can do research on Asian Monsoon based on the fact that $\delta^{13}C$ of C3 plants and C4 plants are consistently different each other and that they are distributed differently with respect to salinity. In Korea, paleoenvironmental studies using stable isotopes are not popular yet because of low academic interests on the methodology and difficulties of obtaining proper sediment samples. Interesting results can be produced to answer paleoenvironmental questions of Korea if scientists isotopically analyze sediment cores from a paleo-lake such as Hanon in Jeju island, peat bogs such as Mujechi-Neup and Yong-Neup, and coastal wetlands.

• Journal of Radiation Protection and Research
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• v.35 no.3
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• pp.117-123
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• 2010

Plutonium is by far the most important of the transuranic elements which have been released into the environment due to radio-toxicity and long term radiation effects on humans. And Pu isotope ratio ($^{240}Pu/^{239}Pu$) is of great interest because this ratio is used as a fingerprint for different sources. Mass spectrometry has been used as an useful atom counting technique with several advantages over decay counting techniques for the determination of Pu isotopes. It enables a determination of Pu isotope ratio in the environmental samples with a low detection limit and a short determination time. An ICP-MS is the representative mass spectrometry for Pu determination. In this study, the precision of $^{240}Pu/^{239}Pu$ isotope ratio was improved by using 4 multiple ion counters of MC-ICP-MS. The detection limit of $^{239}Pu$ and $^{240}Pu$ were $0.10\;fg\;ml^{-1}$ ($0.24\;{\mu}Bq\;ml^{-1}$), $0.12\;fg\;ml^{-1}$ ($0.97\;{\mu}Bq\;ml^{-1}$), respectively. The relative standard deviation of $^{240}Pu/^{239}Pu$ isotope ratio was less than 1 % in trace level. The various reference materials (seawater, soil and sediment) were analyzed to verify this method and their analytical results were in good agreement with the certified (or recommended value) value.

• Journal of Radiation Protection and Research
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• v.43 no.3
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• pp.120-123
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• 2018

Background: Analysis of enrichment of $UO_2$ is important to verify the information declared by the license-holders. The redundancy methods are required to guarantee the analysis result. Korea Institute of Nuclear Nonproliferation and Control (KINAC) used to analyze it with alpha spectrometry and consign to Korea Basic Science Institute (KBSI) Thermal Ionization Mass Spectrometry (TIMS). This article evaluated the similarity of the results with two methods and derive correlation equation. It could be compared to the results measured by TIMS running by KBSI. Materials and Methods: There are not many certified materials for the uranium enrichment value. Therefore, 34 uranium pellets, which have the wide range of uranium enrichment from 0.21 to 4.69 wt%, were used for the experiments by the alpha spectrometry and the TIMS. Results and Discussion: The study shows there are the tendency of analyzed enrichment by each equipment. It shows uranium enrichment with alpha spectrometry evaluated 17% higher than that with TIMS on average. The regression equations were also derived in case the similarity between the two results with two methods is lower than predicted. Two experiments were designed to compare the effect of number of samples. The $R^2$ was 0.9977 with 34 pellets. It shows the equation is appropriate to predict the enrichment values by TIMS with that of alpha spectrometry. The $R^2$ was 0.9858 with four pellets for ten times. The $R^2$ decreased while the number of samples increased. The discrepancy between the lowest and highest enrichment seems to be one of the reason for it. Conclusion: KINAC expects the first equation with 34 samples is useful to predict the result with TIMS, the redundancy method, based on the alpha spectrometry. The extra samples are necessary to collect if the enrichment value analyzed by TIMS is lower than the value predicted with the equation. Further study would be followed related to the impact of the peak counts for each uranium isotopes, sample amount and number of experiments when TIMS established in KINAC by the end of 2018.

• Economic and Environmental Geology
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• v.49 no.2
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• pp.89-95
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• 2016

Mo isotope, one of highly redox-sensitive isotopes, has been shown to be useful tracers of geochemical processes. Many studies for Mo isotope have documented with the help of recently developed analysis tools, but it has not yet been documented in the Korea. In this study, we introduce two-stage column separation method of Mo using column tube (BioRad PolyPrep(R) column, 10 ml) and anion exchange resin (BioRad Resin AG(R) 1-X8, 200-400 mesh). Mo isotope ratios in the solid SRMs (BHVO-2, SDO-1, PACS-2) and liquid SRM (IAPSO) were measured on MC-ICP-MS (Multi-collector Inductively Coupled Plasma Mass Spectrometer) and then compared with reference Mo isotope ratios. Mo isotope ratios in our study overlap with reference Mo isotope ratios within analytical error.

• Economic and Environmental Geology
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• v.49 no.5
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• pp.361-370
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• 2016

It is well known that the inflow of rainwater and the infiltration of groundwater to sewerage (I/I) increase the sewage and burden sewage treatment plants and lower their treatment efficiency. Therefore, it is important to estimate the amount of I/I. In this study, well groundwaters, public water supplies (PWSs), and sewage and rainwater channels were investigated to check whether oxygen and deuterium isotopes could be used as a tool for I/I estimation. This study shows that the isotopic composition of PWS in Jeonju area is very consistent over time and distinctly lighter than the circulating local rainwater (CLR) because it is supplied from Yongdam Dam, which is located about 40 km inland to the east in the mountainous area. Considering the fact that sewage mostly originates from the PWS, we could calculate the amounts of CLR in the sewerage from a monitoring station using unaffected rainwater and tap water as mixing end members. The calculation revealed that the CLR fraction ranged from 50% to 90% depending on observation time. This is well supported by the dilute natures of the sewages at the station. The fraction of PWS in investigated well waters were about 46%, indicating that leaking of PWS is very serious and is an important groundwater source in the study area. Since the infiltration of such groundwater may not alter the isotopic composition of sewage significantly, the actual I/I would be much greater than the calculated ones.

• The Journal of Engineering Geology
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• v.24 no.4
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• pp.535-550
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• 2014

The origins and varieties of natural radioactive materials, including uranium and radon-222, were examined in a drilled borehole extending to a depth of 120 m below the surface in the Goesan area. In addition to core samples, eight groundwater samples were collected at different depths, using a double packer system and bailer, and their geochemical characteristics were determined. Most of the rock samples from the drilled core consisted of granite porphyry, with sedimentary rocks (slate, carbonate, or lime-silicates) and pegmatite occurring in certain sections. The pH of samples varied from 7.8 to 8.4, and the groundwater was of a Na-$HCO_3$type. Uranium and thorium concentrations in the core were < 0.2-14.8 ppm and 0.56-45.0 ppm, respectively. Observations by microscope and an electron probe microanalyzer (EPMA) showed that the mineral containing the natural radioactive materials was monazite contained in biotite crystals. The uranium, which substituted for major elements in the monazite, appeared to have dissolved and been released into the groundwater in a shear zone. Concentrations of Radon-222 in the borehole showed no close relationship with levels of uranium. The isotopes of noble gases, such as helium and neon, would be useful for analyzing the origins and characteristics of the natural radioactive materials.

• Parasites, Hosts and Diseases
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• v.30 no.1
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• pp.33-42
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• 1992

Naegleria fowleri, a free-living amoeba commonly found in moist soil and fresh water, enters the body via the nasal mucosa and migrates along the olfactory nerve to t he brain, where it causes acute amoebic meningoencephalitis. In the present study 7 clones secreting monoclonal antibodies (McAbs) against N. fowleri were produced and the effector function of them was investigated. Their isotopes were IgGl (Nf 1, Nf 154), 19G3 (Nf 137) and 19A (Nf 1, Nf 2, Nf 256, Nf 279). Five McAbs (McAb Nf 2, Nf 279, Nf 27, Nf 154, Nf 137) were specific for N. fowleri by ELISA and recognized the antigenic determinants located on the trophoBoite surface by IFAT and immunoperoxidase stain. These aye McAbs had capacity to agglutinate N. fowleri trophozoites and inhibited the growth of the amoeba in culture medium. McAb Nf 2 inhibited proliferation of trophozoites in vitro significantly. Also the cytotoxicity of JV. fowleri against CHO cell was reduced in the presence of McAb Nf 2 and McAb Nf 154. From these results McAb Nf 2 was confirmed to weaken the virulence of the amoeba among 7 screened McAbs.

• Korean Journal of Ecology and Environment
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• v.50 no.4
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• pp.422-431
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• 2017

The biogeochemical information of riverine organic matter gives a detailed and integrated recording of natural and anthropogenic activity within a watershed. To investigate the changes in quality and quantity of organic carbon transporting from mountain to ocean via river channels, we estimated the concentrations of dissolved (DOC) and particulate organic carbon (POC), and then traced the source origin of POC using stable carbon isotopes ratio before and after summer rainfalls in the Tamjin River and Ganjin Bay, Korea. Along the small watershed, a total of 13 sites including headwaters, dam reservoir, river and estuary were established for the study. We found some interesting findings in the aspect of distribution of DOC/POC concentration changing their origin sources dynamically flowing downstream. In particular, the river channel transport downstream mainly DOC to river mouth, although upper dam reservoir increased POC concentration by phytoplankton production in summer. Whereas, in the river mouth and estuary, POC was dominated not only by local supply from nearby reed saltmarsh, but also by marine phytoplankton production, respectively. The findings can contribute to increasing the understanding of riverine organic carbon transport in upper large dam and lower open estuary system.

• Journal of radiological science and technology
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• v.34 no.4
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• pp.351-357
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• 2011

The $^{18}F$-FDG is one of the widely used isotopes for PET/CT scans. Dose amount injected to the patient depends on the characteristics of PET/CT systems. Obviously, the technologists who contact with patients would be exposed as well. In this study, we evaluated the exposed dose of the technologist who works on the PET/CT scanner. The exposed dose were measured every month with the TLDs from 6 technologists. Each technologist is shift-worker who manages 3 different PET/CT systems(Scanner 1(S1): 0.15 mCi/kg, Scanner 2(S2): 0.17 mCi/kg, Scanner 3(S3): 0.12 mCi/kg). The average exposed doses of technologists for each PET/CT system were measured as 0.76 mSv for S1, 0.93 mSv for S2 and 0.47 mSv for S3. The maximum dose was 1.12 mSv and minimum was 0.42 mSv. The results showed that there was a correlation between exposed dose and PET/CT system(p<0.005). Less injected dose for patient occurs less exposed dose for technologist. Various studies for the low dose PET/CT system are required for not only the patient but also the technologist.