• Journal of Korean Society of Environmental Engineers
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• v.38 no.1
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• pp.42-46
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• 2016

The radioactive iodine ($^{131}I$) presents in the environment through the excrete process of nuclear medicine patients. In the detecting of low level of $^{131}I$ in the public water, the counting uncertainty has an effect on the accuracy and reliability of detecting $^{131}I$ radioactivity concentration. In this study, the contribution of sample amount, radioactivity concentration and counting time to the uncertainty was investigated in the case of public water sample. Sampling points are public water and the effluents of a sewage treatment plant at Sapkyocheon stream, Geumgang river. In each point, 1, 10 and 20 L of liquid samples were collected and prepared by evaporation method. The HPGe (High Purity Germanium) detector was used to detect and analyze emitted gamma-ray from samples. The radioactivity concentration of $^{131}I$ were in the range of 0.03 to 1.8 Bq/L. The comparison of the counting uncertainty of the sample amount, 1 L sample is unable to verify the existence of the $^{131}I$ under 0.5 Bq/L radioactivity concentration. Considering the short half-life of $^{131}I$ (8.03 days), a method for measuring 1 L sample was used. However comparing the detecting and preparing time of 1, 10 L respectively, detecting 10 L sample would be an appropriate method to distinguish $^{131}I$ concentration in the public water.

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.231-238
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• 1995

Tc-99m-MIBI (Sestamibi) myocardial SPECT along with TI-201 tomographic Imaging has demonstrated wide application and high image quality sufficient for the diagnosis of myocardial perfusion defect, which consequently reflects regional myocardial blood flow. The qualitative values of myocardial SPECT with Tc-99m-MIBI as well ds the quantitative cases depend in some degree on the reconstruction techniques of multiple projections. Filtered backprojection (FBP) Is the common standard method for reconstruction rather than the complicated and time-consuming arithmetic methods. In FBP it is known that the distribution of radioactivity in reconstructed transverse slices varies with the selected litter parameters such as cutoff frequencies and order (Butterworth case) The cutoff frequencies used in clinicAl practice partially remove and decrease the true radioactive distribution and alter the pixel counts, which lead to underestimation of true counts in specific myocardial regions. In this study, we have investigated the effect of cutoff frequencies of reconstruction filter on the artifactually induced perfusion defects, which are often demonstrated near inferior and/or inferoseptal cardiac walls due to the intense hepatic uptake of Tc-99m-MIBI. A computerized method for Identifying the relative degree of artifactual perfusion defect and for comparing those degrees along with the relative amount of hepatic uptake to myocardium was developed and patient images were studied to observe the quantitative degree of underestimation of myocardial perfusion, and to propose some reasonable threshold of cutoff frequency in the diagnosis of perfusion defect quantitatively. We concluded that from the quantitative viewpoint cutoff frequencies may be used as high as possible with the sacrifice of homogeneity of image quality, and those frequencies lower than the common 0.3 Wyquist frequency would reveal severe degradation of radioactive distribution near inferior and/or inferoseptal myocardium when applying Butterworth or low pass filter.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.297-304
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• 2018

U.S. nuclear power plant decommissioning guidelines(MARSSIM and MARLAP) are recommends to use DQOs when planning and conducting site surveys. The DQOs which is constructed in the site survey planning stage provide a way to make the best use of data. It helps we can get the important information and data to make decisions as well. From fifth to seventh steps of DQOs are the process of designing a site survey by using the collected data and information in the previous step to make reasonable and reliable decisions. The gray region that is set up during this process is defined as the range of concentrations where the consequences of type II decision errors are relatively small. The gray region can be set using DCGL and the average concentration of radionuclide in the sample collected at the survey unit. By setting up the gray region, site survey plan can be made most resource-efficient and the consequences on decision errors can be minimized. In this study, we set up the gray region by using the DCGL of Kori-1 which was derived from the previous research. In addition, we proposed a method to assess the concentration of radionuclide in samples for making decisions correctly.

• Korean journal of applied entomology
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• v.20 no.2 s.47
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• pp.117-121
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• 1981

The screening method of varietal resistance on the plant hoppers has generally been evaluated as a reaction of plant after infesting insects. However, feeding amount of insects to the varieties was investigated in this experiment. The new method using isotope $^{32}P$ for rice varietal resistance to plant hoppers was carried out through the following method. Insects tested were caged for a few hours on the plants which had absorbed $^{32}P$ solution in small vials for $24\~48\;hours$. After feeding, insects were killed in the refrigerator with formalin solution, and then were measured by the feeding amount as a count per minute (CPM) with the G.M. Counter. The results obtained were summarized as follows; 1. The apparatus of Type D(Fig. 2) was most effective and the safest among four others. 2. The optimum amount of $H_3PO_4$ solution was found to be $2\~3m1$. 3. Radioactivity of $0.7\mu\;Ci.\;^{32}P$ was sufficient to check varietal difference of feeding amount by the brown planthopper. 4. Radioisotope was found from the body of insects but not in the cuticular layer nymphs cast off.

• Progress in Medical Physics
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• v.12 no.1
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• pp.19-29
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• 2001

In dose modeling, the shape of actual source and sealed capsule are important parameter to determine the physical dose computation. The author investigated the effect of filter of source self-absorption and sealed capsule to designed the high dose rate Ir-192 source for Ralstron(Japan) unit. The size of source designed to 1.5 mm $\Phi$ x 1.5mm length of actual source sealed with stainless steel which is 3.0mm $\Phi$ x 12.0mm length connected to driving cable. The dose attenuation was derived 66.3 % from 2655 segmented source at reference point of 10mm lateral distance of source. The output dose rate factor in tissue for designed source showed 0.0013511 cGy/mCi-sec in reference point at 1cm lateral distance of source center. The dose distribution at inferior of source showed the 52% of that of source tip region, however, the filtering effect was small as 4% at 45degrees of source axis. The dose attenuation within 20 degrees of source axis at near source-cable connector showed large filtering effect as 40% over, but the small effect was revealed isotropic dose distribution at large angle.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.4
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• pp.175-182
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• 1998

Recently it is reported that anomalously low saline surface waters (salinity < 32) occurred at the Ulleung Basin in the East Sea-Japan Sea, during early September to November 1996. Apparent source of such a low saline watermass seems remotely linked to the Changjiang Dilute Water (CDW), which expands to the vicinity of Cheju Island during a flood season. Based on the assumption that waters passing through the Western Channel of the Korea Strait are formed by a mixing of Kuroshio Water and CDW, simplified two end-member mixing model using $^{228}Ra/^{226}Ra$ as a conservative tracer is applied to calculate the contribution of each end member for the formation of low saline surface seawater. Model calculations show CDW contributes $58{\pm}3%$ in September 1996 (S=32.17) and $10{\pm}3%$ in February 1997 (S=34.53) in the formation of surface water flowing into the Western Channel of the Korea Strait. Although results arc deduced from a simplified model with limited data, this study demonstrates that Changjiang discharge is clearly traceable to the interior of the East Sea-Japan Sea in fall season. Undergoing Three Valley Dam construction in the Changjiang River would invoke inevitable changes in the nature and discharge of CDW and its impacts on the marine environment might be significant in the northern East China Sea and even in the Ulleng Basin for coming decades.

• Analytical Science and Technology
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• v.15 no.1
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• pp.1-6
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• 2002

The selective removal of cesium by ammonium molybdophosphate (AMP) was studied in order to reduce an interference by high radioactivity of cesium on the determination of low radioactive elements in leachate of spent fuel. The removal of Cs, U, Ce, La, Co Ca, Na Sr and K was investigated for the leachate and the bentonite in contact with a spent fuel. More than 90% of cesium was removed by AMP and Ca, Na, Co and Sr was remained in 0.1 M $HNO_3$. However, three valence elements such as La and Ce were also removed by AMP. Though a little of potassium of the bentonite components was adsorbed on AMP, the potassium in the bentonite solution diluted to its concentration in a real sample would not affect the capacity of AMP greatly. From another experiment for the separation of strontium as a leaching indicator of spent fuel, the recovery of strontium in 8.0 M $HNO_3$ solution by using Sr-resin (Eichrom, P/N SR-B50-A) was more than 95% by eluting with 0.05 M $HNO_3$.

• Nuclear industry
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• v.35 no.9
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• pp.46-52
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• 2015

1975년 우라늄협회로 출발한 세계원자력협회(WNA)는 원자력을 평화적으로 이용하는 것을 적극 지원하고, 원자력 발전과 핵연료주기 전반에 걸친 원자력 산업 발전을 위하고자 설립한 세계적 민간 기구로, 우라늄 채광부터 변환, 농축, 핵연료 제조, 원자력발전 운영, 기자재(설비) 제작 및 사용후핵연료 처분에 이르기까지 원자력발전의 전 주기 산업을 촉진하고 관련 정보를 지원하고 있다. 2001년 지금의 명칭으로 변경한 WNA는 전 세계 원자력산업체와 원자력 관련 기관, 대학 등 175개 회원사를 두고 상호 협력과 전문 인력 교육 기반 강화, 국제화에 적극 나서고 있으며, 원자력산업 정보 제공과 교환을 위해 관련 보고서와 자료도 수시로 발행하고 있다. 2013년부터 WNA를 이끌고 있는 아그네타 라이징 사무총장은 지난 11월 영국 런던 소재 WNA를 방문한 <원자력신문>과의 인터뷰를 통해, 원전과 주변지역 주민의 갑상선암 발병에 대한 인과 관계에 대하여 "갑상선암 발병이 원전과 연관성 있다는 주장은 과학적 근거가 없다"고 단호히 말하고, "한국과 유사한 사례가 해외 원자력계(과학계)와 의학계에 보고된 적이 있냐"는 질문에 "해외에서 정상 운영되고 있는 원전 시설은 국제방사선방호위원회(ICRP)의 엄격한 기준(ICRP-60)이 적용하고 있으며, 방사선 방호와 관련된 연구보고서(논문)를 꾸준히 내고 있지만 원전 주변 주민에 대한 여러 역학 조사에서도 갑상선암이 증가했다는 사례는 보고된 바 없다"고 말했다. 또한 "실제로 일본 원폭 생존자 연구와 체르노빌 원전 주변 주민 연구에 의하면 20세 이상의 성인에서 방사선 노출에 의해 갑상선암이 증가한다는 증거는 없었다."면서 "체르노빌 사고와 후쿠시마 원전 사고 이후 방사선 누출로 인해 방사선이 갑상선암의 발생률을 증가시키는 것으로 알려졌지만 실제로 원전에서 발생하는 방사능은 갑상선암을 유발시킬 수 있는 양에 비해 아주 적다. 그럼에도 원전 시설에서 나오는 방사능 수치에 대해 제대로 밝히는 기관이 없기 때문에 원전 주변에 살아도 영향을 받는 것으로 오해할 수 있다."고 덧붙였다. 아그네타 라이징 사무총장은 스웨덴 출신의 방사선 방호 전문가로, 스웨덴 국영기업 Vattenfall AB 그룹에서 원자력 에너지 환경 분야 최고 전문가로 활동했으며, 스웨덴원자력학회, 유럽원자력학회, 세계여성원자력전문인회(WiN-Global) 회장 등을 역임했다. 인터뷰 전문을 게재한다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.136-136
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• 2017

화학제염 기술은 산화제, 환원제, 금속이온, 무기산등이 혼합되어 있는 화학용액을 사용하여 원전기기 계통 내부에 생성된 고방사능 준위의 산화막과 오염물질을 제거하는 기술이다. 원전의 해체 및 유지보수에 있어 방사능 피복저감을 위한 필수적인 기술이다. 현재 원전 해체 산업은 잠재성이 높은 고부가가치 창출 산업으로 주목을 받고 있다. 원전 보유국의 경우, 기존 상용 제염기술과는 차별성 있는 제염기술을 확보하고자 노력하고 있다. 기존의 공정과 비교하여 공정비용 및 시간을 감소시킬 수 있어야 할 뿐만 아니라, 화학용액에 의한 원전 계통 금속 부품의 부식 및 손상을 최소화해야 한다. 금속 부품이 화학약품에 의한 부식손상을 받는다면 금속 부품의 수명 및 재활용 가치가 감소하기 때문에, 화학제염 기술 적용에 있어 용액에 대한 재료의 건전성 평가가 사전에 필히 이루어져야 한다. 본 연구에서는 원전 냉각재 펌프용 재료로 주로 사용되는 Stainless 304강을 시험편으로 선정하여, 화학제염 시험공정 3가지에 대한 부식손상 특성을 규명하였다. 산화공정은 과망간산($HMnO_4$) 용액을 공통으로 사용하였으며, 산화공정 종료 후 환원공정은 각 시험공정에 따라 시험공정 1은 옥살산($H_2C_2O_4$) 2000ppm, 시험공정 2는 옥살산($H_2C_2O_4$)1500ppm + 시트르산($H_8C_6O_7$)500ppm, 그리고 시험공정 3은 옥살산($H_2C_2O_4$) 3000ppm 용액을 각각 투입하여 수행하였다. 산화, 환원공정을 1Cycle로 하여, 각 시험공정 별로 총 5Cycle을 실시하였다. 각 시험공정 Cycle종료 후 시험편을 취외하여 무게감량측정, SEM(Scanning electron microscope) 분석, 3D현미경분석 그리고 타펠분극 실험을 실시하였다. 각 분석결과를 토대로 하여, Stainless 304강에 대한 화학제염 시 모델별 시험공정에 따른 부식특성을 규명하였다.

• Environmental and Resource Economics Review
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• v.14 no.1
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• pp.1-24
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• 2005

One of the most important factors that determine the quality of a stated preference study is questionnaire design. This study introduces strategies for enhancing the rationality and testing for the validity of choice experiments(CE) using "example" choice questions that mimic the main choice questions. From the case study of WTP for reduced radon radiation exposures in the home, the study found that screening out irrational responses, 12% of the effective responses, resulted in a meaningful increase in model fit. Meanwhile the study tested for anchoring effects, as a way of confirming the divergent validity of the study, by looking at equality of models estimated for two subsamples. The overall test results were mixed. The pros and cons of the questionnaire design strategy employed are also reported.