• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.3
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• pp.340-349
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• 2021

Three specimens (33.6-44.8 mm in standard length) of the family Bregmacerotidae, collected from the waters off south-western Jeju-do Island in October 2016, were identified as Bregmaceros nectabanus on the basis of morphological and molecular methods (DNA barcoding). This species is characterized by having 50-52 2nd dorsal fin rays, 52-53 anal fin rays, 13 principal caudal fin rays, an unpigmented abdomen, irregularly distributed dorsal chromatophores, and the origin of a dorsal fin slightly behind the anal fin. This is the first reliable record of B. nectabanus in Korea. According to Yoo et al. (1992), we propose a Korean name "Tae-Pyeong-Yang-Nal-Gae-Myeol" for this species. Also, we suggest key to species of these eight bregmacerotids from the northwestern Pacific.

• Research in Mathematical Education
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• v.26 no.4
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• pp.271-289
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• 2023

This research investigates the development of elementary students' concepts of line segments, straight lines, and rays, employing metaphor analysis as a research methodology. By analyzing metaphorical expressions, the research aims to explore how elementary students form these geometric concepts line segments, straight lines, and lays and evolve their understanding of them across different grades. Surveys were conducted with elementary school students in grades three to six, focusing on metaphorical expressions and corresponding their reasons associated with line segments, straight lines, and rays. The data were analyzed through coding and categorization to identify the types in students' metaphorical expressions. The analysis of metaphorical expressions identified five types: straightness, infinity or direction, connections of another geometric concepts, shape and symbols, and terminology.

• Journal of Trauma and Injury
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• v.37 no.1
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• pp.86-88
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• 2024

Misinterpreting radiographic findings can lead to unnecessary interventions and potential patient harm. The urgency required when responding to the compromised health of trauma patients can increase the likelihood of misinterpreting chest x-rays in critical situations. We present the case report of a trauma patient whose skin fold artifacts were mistaken for pneumothorax on a follow-up chest x-ray, resulting in unnecessary chest tube insertion. We hope to help others differentiate between skin folds and pneumothorax on the chest x-rays of trauma patients by considering factors such as location, shape, sharpness, and vascular markings.

• Journal of Astronomy and Space Sciences
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• v.41 no.1
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• pp.17-23
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• 2024

The safety of electronic components used in aerospace systems against cosmic rays is one of the most important requirements in their design and construction (especially satellites). In this work, by calculating the dose caused by proton beams in geostationary Earth orbit (GEO) orbit using the MCNPX Monte Carlo code and the MULLASSIS code, the effect of different structures in the protection of cosmic rays has been evaluated. A multi-layer radiation shield composed of aluminum, water and polyethylene was designed and its performance was compared with shielding made of aluminum alone. The results show that the absorbed dose by the simulated protective layers has increased by 35.3% and 44.1% for two-layer (aluminum, polyethylene) and three-layer (aluminum, water, polyethylene) protection respectively, and it is effective in the protection of electronic components. In addition to that, by replacing the multi-layer shield instead of the conventional aluminum shield, the mass reduction percentage will be 38.88 and 39.69, respectively, for the two-layer and three-layer shield compared to the aluminum shield.

• Journal of the Korean Society of Radiology
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• v.7 no.6
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• pp.377-381
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• 2013

The study attempted to analyze items presented in Act on safety control of radioactive rays around living environment, which has been recently enacted. The test items have been divided into cosmic rays, cosmic rays, terrestrial radiation, and byproduct, etc., and the selected locations for measurement included an airplane at 8000m in the air, mountainous area at 1000m above sea level, 15m-underground building, construction site, and seashore at 0m altitude. The test showed that, based on cosmic rays, plane at 8000m in the air had 4.91mSv/y of effective dose per year. The mountainous area at 1000m above sea level, which was chosen to measure cosmic rays and terrestrial radiation, was measured 0.35mSv higher than the seashore at 0m in altitude due to the effect of cosmic rays and terrestrial radiation from the greater height above sea level. The construction site, chosen as a location to measure byproduct, showed the highest value among the items with 6.66mSv, which is as 10times high as that of a completed building. The seashore at 0m in altitude had 5.96mSv, and, 15m-underground building, based on terrestrial radiation, was the lowest with 4.91mSv. This suggests that, despite the assumption that terrestrial radiation will have greater effect deeper underground, it did not affect inside the building significantly. This study showed that the items presented in Act on safety control of radioactive rays around living environment were not close to effective dose limit for radiation workers proposed by ICRP. However, they were between 4 and 7 times higher than that for general public. This suggests that there should be continuous research on and attention to Safe Management of Daily Surrounding Radiation Act, which is still at its beginning stage.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.547-553
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• 2017

In the current medical field, lead is widely used as a radiation shield. However, the lead weight is very heavy, so wearing protective clothing such as apron is difficult to wear for long periods of time and there is a problem with the danger of lethal toxicity in humans. Recently, many studies have been conducted to develop substitute materials of lead to resolve these problems. As a substitute materials for lead, barium(Ba) and iodine(I) have excellent shielding ability. But, It has characteristics emitting characteristic X-rays from the energy area near 30 keV. For patients or radiation workers, shielding materials is often made into contact with the human body. Therefore, the characteristic X-rays generated by the shielding material are directly exposured in the human body, which increases the risk of increasing radiation absorbed dose. In this study, we have developed the FLUKA transport code, one of the most suitable elements of radiation transport codes, to remove the characteristic X-rays generated by barium or iodine. We have verified the reliability of the shielding fraction of the structure of the structure shielding by comparing with the MCPDX simulations conducted as a prior study. Using the MCNPX and FLUKA, the double layer shielding structures with the various thickness combination consisting of barium sulphate ($BaSO_4$) and bismuth oxide($Bi_2O_3$) are designed. The accuracy of the type shown in IEC 61331-1 was geometrically identical to the simulation. In addition, the transmission spectrum and absorbed dose of the shielding material for the successive x-rays of 120 kVp spectra were compared with lead. In results, $0.3mm-BaSO_4/0.3mm-Bi_2O_3$ and $0.1mm-BaSO_4/0.5mm-Bi_2O_3$ structures have been absorbed in both 33 keV and 37 keV characteristic X-rays. In addition, for high-energy X-rays greater than 90 keV, the shielding efficiency was shown close to lead. Also, the transport code of the FLUKA's photon transport code was showed cut-off on low-energy X-rays(below 33keV) and is limited to computerized X-rays of the low-energy X-rays. But, In high-energy areas above 40 keV, the relative error with MCNPX was found to be highly reliable within 6 %.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.258-264
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• 2011

Glutathione (GSH) has important roles in cellular defense against oxidative stress, 1) direct scavenging of reactive oxygen species (ROS), and 2) coenzyme of ROS scavenging enzyme like glutathione peroxidases (GPx). GSH peroxidase reduces free hydrogen peroxide to water using 2GSH. $N$-acetyl-L-cysteine (NAC), one of the antioxidants, is used as a precursor for intracellular GSH. In this study, relation of GSH, NAC, and GSH peroxidase was investigated through transcriptional expression of $GPX1$ and $GPX2$, which are GSH peroxidase encoding genes, in yeast cells treated with 0 mM to 20 mM of NAC or in combination with 100 Gy gamma-rays. The transcriptional expression of $GPX1$ and $GPX2$ was induced by NAC and 100 Gy gamma-rays. The gene expression of both GSH peroxidases was decreased with increasing concentrations of NAC in irradiated yeast cells. These results suggest that elevation of intracellular GSH by NAC and oxidative stress and ROS generated from gamma-rays induces expression of GSH peroxidase genes, and that NAC can protect the yeast cells against ROS generated from gamma-rays through direct scavenging of ROS and transcriptional activation of GSH peroxidase.

• Journal of Radiation Protection and Research
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• v.19 no.2
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• pp.121-132
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• 1994

This study concerns about the measurement and the investigation of environmental radiation characteristics which the components and the distribution of exposure rates by terrestrial y-rays in Taegu area. $4^{'}{\phi}{\times}4^{'}$ NaI(T1) scintillation detector with a multichannel analyzer was used in the measurement of y-rays as a part of in-situ spectrometry at twenty eight different locations in this area. The conversion into the exposure rate from the measured ${\gamma}-ray$ spectrum has been carried out leading to a net exposure rate and component ones by $^{40}K,\;^{238}U$ series and $^{232}Th$ series products which are known by the major parts in the terrestrial ${\gamma}-rays$ generally. As a result, the average exposure rate by the terrestrial ${\gamma}-rays$ in Taegu area is $9.4{\mu}R/h$ and the distribution of individual exposure rates shows more or less differences between these locations even after the consideration of diurnal and yearly variations which are always involved in these measurements. The component parts of exposure rates are distributed $^{40}K\;2.9{\sim}4.6{\mu}R/h,\;^{238}U$ series $1.2{\sim}3,\;1{\mu}R/h,\;^{232}Th$ series $2.5{\sim}5.0{\mu}R/h$ over the measured locations.

• Journal of Radiation Protection and Research
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• v.23 no.1
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• pp.33-47
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• 1998

Using a combination of an X-ray generator Installed in radiation calibration laboratory of Korea Atomic Energy Research Institute (KAERI) and a series of 8 radiators and filters described in ISO-4037, monoenergetic fluorescent X-rays from 8.6 keV to 75 keV were produced. This fluorescent X-rays generated by primary X-rays from radiator were discriminated $K_{\beta}$ lines with the aid of filter material and the only $K_{\alpha}$ X-rays were analyzed with the high purity Ge detector and portable MCA. The air kerma rates were measured with the 35 co ionization chamber and compared with the calculational results, and the beam uniformity and the scattered effects of radiation fields were also measured. The beam purities were more than 90 % for the energy range of 8.6 keV to 75 keV and the air kerma rates were from 1.91 mGy/h (radiator : Au, filter : W) to 54.2 mGy (radiator : Mo, filter : Zr) at 43 cm from center of the radiator. The effective area of beam at the measurement point of air kerma rates was 12 cm ${\times}$ 12 cm and the influence of scattered radiation was less than 3 %. The fluorescent X-rays established in this study could be used for the determination of energy response of the radiation measurement devices and the personal dosemeters in low photon energy regions.

• Progress in Medical Physics
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• v.16 no.2
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• pp.53-61
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• 2005

The quality factors for cylindrical ionization chambers for kV X-rays were determined by Monte Carlo calculation and measurement. In this study, the X-rays of 60-300 kV beam (lSO-4037) installed in KFDA and specified in energy spectra and beam qualities, and the chambers of PTW N23333 and N30001 were investigated. In calculations, the $R_{\mu}\;and\;R_{Q,Q_{0}}$ in IAEA dosimetry protocols were determined from the air kerma and the cavity dose obtained by theoretical and Monte Carlo calculations. It is shown that the N30001 chamber has a flat response of $\pm1.7\%$ in $110\~300kV$ region, while the response range of two chambers were shown to $\pm3\~4\%$ in $80\~250kV$ region. From this work we have discussed dosimetry protocol for the kV X-rays and we have found that the estimation of energy dependency is more important to apply dosimetry protocol for kV X-rays.