• Progress in Medical Physics
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• v.6 no.2
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• pp.71-81
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• 1995

Consecutive brain 〔Tc-99m〕ECD SPECT studies before and after acetazolamide (Diamox) administration have been performed with patients for the evaluation of cerebrovascular hemodynamic reserve. However, the quantitaitve potential of SPECT Diamox imaging is limited as a result of degrading fractors such as finite detector resolution, attenuation, scatter, poor counting statistics, and methods of data analysis. Making physical measurements in phantoms filled with known amounts of radioactivity can help characterize and potentially quantify the sensitivities. However, it is often very difficult to make a realistic phantom simulating patients in clinical situations. By computer simulation, we studied the sensitivities of ECD SPECT before and after Diamox administration. The sensitivity is defined as ($\Delta$N/N)/($\Delta$S/S)$\times$100％, where $\Delta$N denotes the differences in mean counts between post-and pre-Diamox in the measured data, N denotes the mean counts before Diamox in the measure data, $\Delta$S denotes the differences in mean counts between post-and pre-Diamox in the model, and S denotes the mean counts before Diamox in the model. In clinical Diamox studies, the percentage changes of radioactivity could be determined to measure changes in radioactivity concentration by Diamox after subtracting pre-from post-Diamox data. However, the optimal amount of subtraction for 100％ sensitivity is not known since this requires a thorough sensitivity analysis by computer simulation. For consecutive brain SPECT imaging model before and after Diamox, when 30％ increased radioactivity concentrations were assingned for Diamox effect in model, the sensitivities were measured as 51.03, 73.4, 94.00, 130.74％ for 0, 100, 150, 200％ subtraction, respectively. Sensitivity analysis indicated that the partial voluming effects due to finite detector resolution and statistical noise result in a significant underestimation of radioactivity measurements and the amount of underestimation depends on the. ％ increase of radioactivity concentration and ％ subtraction of pre-from post-Diamox data. The 150％ subtraction appears to be optimal in clinical situations where we expect approximately 30％ changes in radioactivity concentration. The computer simulation may be a powerful technique to study sensitivities of ECD SPECT before and after Diamox administration.

• Journal of Radiation Protection and Research
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• v.33 no.1
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• pp.27-34
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• 2008

A Korean urban contamination model METRO-K (${\underline{M}}odel$ for ${\underline{E}}stimates$ the ${\underline{T}}ransient$ Behavior of ${\underline{R}}adi{\underline{O}}active$ Materials in the ${\underline{K}}orean$ Urban Environment, which is capable of calculating the exposure doses resulting from radioactive contamination in an urban environment, is taking part in a model testing program EMRAS (${\underline{E}}nvironmental$ ${\underline{M}}odelling$ for ${\underline{RA}}diation$ ${\underline{S}}afety$) oragnized by the IAEA (${\underline{I}}nternational$ ${\underline{A}}tomic$ ${\underline{E}}nergy$ ${\underline{A}}gency$). For radioactive contamination scenarios of Pripyat districts and a hypothetical RDD (${\underline{R}}adiological$ ${\underline{D}}ispersal$ ${\underline{D}}evice$), the predicted results using METRO-K were submitted to the EMRAS's Urban Contamination Working Group. In this paper, the predicted results for the contamination scenarios of a Pripyat district were shown in case of both without remediation measures and with ones. Comparing with the predictied results of the models that have taken part in EMRAS program, a feasibility for decision-making support of METRO-K was investigated. As a predicted result of METRO-K, to take immediately remediation measures following a radioactive contamination, if possible, might be one of the best ways to reduce exposure dose. It was found that the discrepancies of predicted results among the models are resulted from 1) modeling approaches and applied parameter values, 2) exposure pathways which are considered in models, 3) assumptions of assessor such as contamination surfaces which might affect to an exposure receptor and their sizes, 4) parameter values which are related with remediation measures applied through literature survey. It was indentified that a Korean urban contamination model METRO-K is a useful tool for dicision-making support through the participation of EMRAS program.

• Journal of Radiation Protection and Research
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• v.37 no.3
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• pp.108-115
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• 2012

The Urban Areas Working Group within the EMRAS-2 ($\underline{E}$nvironmental $\underline{M}$odelling for $\underline{RA}$diation $\underline{S}$afety, Phase 2), which has been supported by the IAEA (International Atomic Energy Agency), has designed some types of accidental scenarios to test and improve the capabilities of models used for evaluation of radioactive contamination in urban areas. For the comparison of the results predicted from the different models, the absorbed doses in air were analyzed as a function of time following the accident with consideration of countermeasures to be taken. Two kinds of considerations were performed to find the dependency of the predicted results. One is the 'accidental season', i.e. summer and winter, in which an event of radioactive contamination takes place in a specified urban area. Likewise, the 'rainfall intensity' on the day of an event was also considered with the option of 1) no rain, 2) light rain, and 3) heavy rain. The results predicted using a domestic model of METRO-K have been submitted to the Urban Areas Working Group for the intercomparison with those of other models. In this study, as a part of these results using METRO-K, the countermeasures effectiveness in terms of dose reduction was analyzed and presented for the ground floor of a 24-story business building in a specified urban area. As a result, it was found that the countermeasures effectiveness is distinctly dependent on the rainfall intensity on the day of an event, and season when an event takes place. It is related to the different deposition amount of the radionuclides to the surfaces and different behavior on the surfaces following a deposition, and different effectiveness from countermeasures. In conclusion, a selection of appropriate countermeasures with consideration of various environmental conditions may be important to minimize and optimize the socio-economic costs as well as radiation-induced health detriments.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.250-250
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• 2011

지정학적으로 3면이 바다로 접하고 있는 우리나라 해안가 주변의 원자력발전소는 관류형 냉각 방식(Once-through cooling System)을 채택하고 있기에, 이 계통을 통과한 냉각수는 주변해역으로 흘러들어가 주변 환경에 영향을 줄 수 있다. 또한 동해 주변 인접국들의 활발한 원자력 이용과 방사능 물질의 수송 등으로 인해 방사능 사고 위험이 증대됨에 따라 동해 원전 주변의 해양방사성물질 거동에 대한 필요성이 제기되고 있다. 이에 따라 동해의 해양환경을 조사 분석하여 해역에서의 오염 물질의 거동 파악이 중요하고, 산업시설 주변 연안의 오염물 이동 및 해석을 위해 오염물의 시 공간적으로 농도를 추정하는 것이 중요한 사항이다. 따라서 본 연구에서 수직 수평적으로 2차원 및 3차원화가 용이한 EFDC 모델을 사용하였다. 국립해양조사원에서 발간하는 DC103의 수치해도를 이용하여 모델영역은 동서방향으로 171km, 남북방향으로 235km로 설정하고, 격자간격은 $1km{\times}1km$의 정방향 격자를 사용하여 동해 월성 주변의 조위 시계열 검증 및 조화분석을 통한 검증을 실시한 결과 관측한 결과와 양호한 재현성을 나타내었다. 또한 국립수산과학원에서 제공되고 있는 년별 수온, 염분 자료 등의 해양환경과 지형적 특성을 고려하여 오염 물질의 이동 경로를 파악함으로써 사고시 피해를 줄이고자 한다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.544-548
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• 2003

The Irradiation test of bar code label tagged on radioactive waste container was done to determine the effect of radiation. Low and medium radioactive waste is that below total activity of 4,000 Bq/g according to the Korean nuclear law. The irradiation amount to radiate bar code label tagged on radioactive waste container was calculated by MCNP-4b computer code. The nuclide such as Co-60 and Cs-137 was assumed to contribute 50% of total activity. Real irradiation amount for bar code label was finally calculated by the dimensions of the container and the bar code label. The Identification of post and the physical deflection of irradiated bar code label was tested by the bar code reader. The coated bar code label was suitable to use on low and medium radioactive waste container.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.05a
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• pp.147-152
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• 2003

원자로 압력용기 저합금강들은 원자로 가동 중 중성자 조사에 의해 재질열화 (material degradation)가 발생한다. 그러므로 계속적인 재질열화의 평가는 발전소의 수명을 예측, 평가하기 위해서 매우 중요하다. 그러나 표준시편을 이용한 인장시험, 충격시험 및 파괴인성 시험법 등은 조사시편의 크기 및 수량에 제한이 따르고, 높은 방사능으로 인해 시험편의 취급에도 제약을 받게 된다. 따라서 소형시편을 이용한 재료의 손상평가기술의 필요성이 부각되었고, 소형펀치시험(small punch test, SP test)은 그 중 하나의 유용한 시험 방법이다.(중략)

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2008.05a
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• pp.309-310
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• 2008

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.237-238
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• 2001

라돈(Rn-222)은 우라늄(U-238) 방사능계열의 원소로서 라듐(Ra-226)의 알파($\alpha$)붕괴시 자연생성되는 가스상 물질이다. 암석 내에서 생성되어 공극내에서 물에 용해된 라돈은 붕괴하지 않고 상태를 유지하게 되는데 이런 라돈이 존재하는 암석층으로부터 지하수를 취수할 경우, 상당량의 라돈이 지하수속에 용해되어 있을 수 있다. 이렇게 용해된 상당량의 라돈은 실내공기로 휘발하면서 주변으로 확산하게 된다. (중략)

• Journal of Radiation Protection and Research
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• v.22 no.2
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• pp.111-117
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• 1997

Recently, the conclusion of Comprehensive Test Ban Treaty(CTBT) is globally constructing a network system for nuclear test monitoring. The radionuclide experts of the Conference on Disarmament recommended that the detection of nuclear debris in the atmosphere was an essential factor of nuclear test monitoring and proposed the technical requirements. Based on those requirements, atmospheric radionuclide monitoring system to detect nuclear debris generated from the nuclear explosion test was composed. The system is comprised of high volume air sampler(HVAS), filter paper presser and high purity germanium detector(HPGe). Minimum detectable concentrations(MDCs) of the key nuclides requiring in CTBT monitoring strategies are determined by considering of decay time, counting time and flow rate of the high volume air sampler for the rapid explosion and the optimum measurement condition. The results were selected $10{\pm}$2h, $20{\pm}$2h and $850{\pm}50m^3$/h as parameters, respectively. The relation between the natural air-borne radionuclide concentration of $^{212}Pb$ and MDC were calculated which gave effect in the Compton continuum baseline due to those nuclides in the gamma-ray spectroscopy. These results can be used as an actually tool in the CTBT monitoring strategies.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.3
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• pp.301-308
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• 2018

Anthropogenic radioactive noble gases formed by nuclear fission are significant indicators used to monitor the nuclear activity of neighboring countries. In particular, radioactive xenon, owing to its abundant generation and short half-life, can be used to detect nuclear testing, and radioactive krypton has been used as a tracer to monitor the reprocessing of nuclear fuels. Released radioactive noble gases are in the atmosphere at infinitesimal amounts due to their dilution in the air and their short half-life decay. Therefore, to obtain reliable and significant data when performing measurement of noble gases in the atmosphere, the minimum detectable activity (MDA) for noble gases should be defined as low as possible. In this study, the MDA values for radioactive xenon and krypton were theoretically obtained based on the BfS-IAR system by collecting both noble gases simultaneously. In addition, various MDA methods, confidence level and analysis conditions were suggested to reduce and optimize MDA with an assessment of the factors affecting MDA. The current investigation indicated that maximizing the pretreatment efficiency and performance maintenance of the counter were the most important aspects for Xe. In the case of Kr, since sample activities are much higher than those of Xe, it is possible to change the target MDA or to simplification of the analysis system.