• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.367-373
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• 2023

Aircrews and passengers are exposed to radiation from cosmic rays and secondary scattered rays generated by reactions with air or aircraft. For aircrews, radiation safety management is based on the exposure dose calculated using a space-weather environment simulation. However, the exposure dose varies depending on solar activity, altitude, flight path, etc., so measuring by route is more suggestive than the calculation. In this study, we developed an instrument to measure the cosmic radiation dose using a general-purpose Si sensor and a multichannel analyzer. The dose calculation applied the algorithm of CRaTER (Cosmic Ray Telescope for the Effects of Radiation), a space radiation measuring device of NASA. Energy and dose calibration was performed with Cs-137 662 keV gamma rays at a standard calibration facility, and good dose rate dependence was confirmed in the experimental range. Using the instrument, the dose was directly measured on the international line between Dubai and Incheon in May 2023, and it was similar to the result calculated by KREAM (Korean Radiation Exposure Assessment Model for Aviation Route Dose) within 12%. It was confirmed that the dose increased as the altitude and latitude increased, consistent with the calculation results by KREAM. Some limitations require more verification experiments. However, we confirmed it has sufficient utilization potential as a cost-effective measuring instrument for monitoring exposure dose inside or on personal aircraft.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.201-206
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• 1996

건식가공(Dry Process)이 사용전,후 DUPIC 핵연료의 붕괴열(Decay Heat), Hazard Index, 조사선량률(Dose Rate) 등에 미치는 영향을 계산하고, 그 원인을 분석하였다. DUPIC 사용방안으로 표준 연소도(35,000 MWD/MTU)의 경우와 장주기 연소도(50,000 MWD/MTU)의 경우를 고려하여 계산하였으며, DUPIC핵연료는 20년 냉각후 가공하는 것을 기준으로 하였다. 또한 DUPIC핵연료 장전시 고려할 수 있도록 사용전 DUPIC 핵연료에 대한 계산을 핵연료 집합체(Bundle) 단위로 하였다. 조사선량과 붕괴열은 건식가공에 상당히 민감한 반응을 보였고 이는 주로 Cs의 제기에 의한 것이다.

• Nuclear industry
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• no.3_4 s.12
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• pp.49-51
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• 1983

미국의 소비자계몽단체인 $\lceil$미국과학${\cdot}$보건협회의$\rfloor$는 $\lceil$조사식품$\rfloor$이란 소책자를 발행했다. 이 소책자는 저선량방사선의 식품조사의 안전성은 명확하며 고선량조사의 경우에도 위험한 결과를 볼 수 없으므로 소비자는 조사식품을 기피한 필요가 없고 오히려 풍요로운 생활을 영위할 수 있게 하는 것으로 환영할만한 것이라고 강조하고 있다. 미국에서는 $83\~84$년중에 상업조사식품이 나올 것으로 전망되는데 소비자의 반응이 주목된다. 다음은 그 소책자의 개요이다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.284-285
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• 2005

Ni/${\gamma}$-Al$_{2}$O$_{3}$의 촉매능 향상을 위하여 고에너지의 전자빔을 사용하여 처리한 후 촉매반응과 표면상태 변화를 관찰하였다. XRD와 XPS 분석 결과로부터 전자빔 처리된 촉매에서 표면의 상대적인 O/Ni의 비가 감소되고 Ni의 산화상태가 변화하였음을 관찰하였다. 2MeV의 준위에서 600 kGy의 선량으로 전자빔을 조사한 촉매에서 가장 높은 전환율과 수득율을 보임으로써 고준위 고선량의 전자빔 처리가 촉매능 향상에 유리함을 알 수 있었다.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.477-485
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• 1999

The grafting of 2,3-epoxypropylmethacrylate (GMA) onto polypropylene fabric was carried out by the $\gamma$-ray preirradiation grafting technique. Subsequently, the GMA-grafted polypropylene fabric was reacted with iminodiacetic acid (IDA) in different mixed solvents to prepare the fibrous metal adsorbent. The grafting extent was found to be dependent on the reaction time, temperature, preirradiation dose and dose rate. The effects of various mixed solvents on the IDA amination onto GMA-grafted polypropylene fabric were investigated. Compared with other mixed solvents, the extent of amination was highest in the dimethylsulfoxide (DMSO)/water, but the reaction did not occur in the water. The adsorption characteristics of various metal ions by the prepared adsorbent were examined when it was immersed in the 100 ppm metal ion solution. The amount of adsorption followed the order:$Pb^{2+}>Co^{2+}>Fe^{2+}$.

• The Korean Journal of Nuclear Medicine
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• v.35 no.5
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• pp.313-323
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• 2001

Purpose: The purpose of this study was to search activated genes that could be related to radiation adaptive response (RAR) induced by low-level radiation from $^{99m}Tc$ in human cell lines. Methods: We used gene discovery array (GDA) and representational difference analysis (RDA) methods. $^{99m}Tc$-pertechnetate was added to $2{\times}106/mL$ NC-37 cells (human lymphoblastic cells) to make concentrations ranging from 148 MBq/mL to 148 Bq/mL by serial 10 fold dilutions. After 44 hours, 2 Gy gamma irradiation was given to them using a Cs-137 cell irradiator. Results: As compared to the control (Con) group to which no $^{99m}Tc$ was added, those cells to which 148 and 14.8 KBq of $^{99m}Tc$ were added showed significantly lower damage to chromosomes, which was evaluated by metaphase analysis. Cells with 148 KBq $^{99m}Tc$ (T148 group) showed most significant protection. Activated genes in the T148 group as compared to Con group were evaluated by GDA and GDA methods. GDA revealed genes of casein kinase 2 (CK2) beta chain, immunoglobulins (lg), human leukocyte antigen (HLA)-B, and two novel genes. Twenty RAR related clones were selected by RDA method. The size of those genes was from 234 to 603 base pairs. Conclusions: RAR was induced by low dose irradiation from $^{99m}Tc$ in NC-37 cell lines. Genes related to the response included CK2, lg, HLA-B in human lymphoblastic cell lines.

• Korean Journal of Veterinary Research
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• v.41 no.1
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• pp.99-104
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• 2001

To determine if micronucleus (MN) assay could be used to predict the absorbed dose of victims after accidental radiation exposure, we carried out to assess the absorbed dose depending on the numerical changes of MN in human peripheral blood lymphocytes after $^{60}Co\;{\gamma}-rays$ exposure in the range of 0.25 to 1 Gy, respectively. The MNs were observed at very low doses, and the numerical changes according to doses. Satisfactory dose-effect calibration curve is observed after low dose irradiation of human lymphocytes in vitro. When plotting on a linear scale against radiation dose, the line of best fit was $Y=(0.02{\pm}0.0009)+(0.033{\pm}0.010)D+(0.012{\pm}0.012)D^2$. The dose-response curve for MN induction immediately after irradiation was linear-quadratic and has a significant relationship between the frequencies of MN and dose. These data show a trend towards increase of the numbers of MN with increasing dose. The number of MN in lymphocytes that were observed in the control group is $0.1610{\pm}0.0093/cell$. Accordingly, MN assay in human peripheral lymphocytes could be a useful in viva model for studying radio-protective drug sensitivity or screening test, microdosimertic indicator and radiation-induced target organ injury. Since MN assay is simple, rapid and reproducible, it will also be a biodosimetric indicator for individual dose assessment after accidental exposure.

• Journal of Radiation Protection and Research
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• v.29 no.3
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• pp.179-186
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• 2004

A single-dosimeter worn on the anterior surface of body of a worker was found to provide significant underestimation of dose to the worker when radiation comes from behind of the human body. Recently, several researchers suggested that this kind of underestimation can be corrected to a certain extent by using an extra dosimeter on the back. But this multiple dosimetry also has the disadvantages like overestimation lowering work efficiency or cost burden. In this study, a single dosimeter introducing asymmetric filters enabled to identify PA exposure was designed by monte-carlo simulation and experiments and its dose evaluation algorithm for AP-PA mixed radiation field was established. This algorithm was applicable to penetrating radiation which had the effective energy more than 100 keV. Besides, the dosimeter and algorithm in this study were possible to be applied to near PA exposure.

• Progress in Medical Physics
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• v.21 no.1
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• pp.113-119
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• 2010

Software for GafChromic EBT2 film dosimetry was developed in this study. The software provides film calibration functions based on color channels, which are categorized depending on the colors red, green, blue, and gray. Evaluations of the correction effects for light scattering of a flat-bed scanner and thickness differences of the active layer are available. Dosimetric results from EBT2 films can be compared with those from the treatment planning system ECLIPSE or the two-dimensional ionization chamber array MatriXX. Dose verification using EBT2 films is implemented by carrying out the following procedures: file import, noise filtering, background correction and active layer correction, dose calculation, and evaluation. The relative and absolute background corrections are selectively applied. The calibration results and fitting equation for the sensitometric curve are exported to files. After two different types of dose matrixes are aligned through the interpolation of spatial pixel spacing, interactive translation, and rotation, profiles and isodose curves are compared. In addition, the gamma index and gamma histogram are analyzed according to the determined criteria of distance-to-agreement and dose difference. The performance evaluations were achieved by dose verification in the $60^{\circ}$-enhanced dynamic wedged field and intensity-modulated (IM) beams for prostate cancer. All pass ratios for the two types of tests showed more than 99% in the evaluation, and a gamma histogram with 3 mm and 3% criteria was used. The software was developed for use in routine periodic quality assurance and complex IM beam verification. It can also be used as a dedicated radiochromic film software tool for analyzing dose distribution.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.10a
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• pp.337.2-337
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• 1999