• Journal of Radiation Protection and Research
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• v.24 no.4
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• pp.187-193
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• 1999

The specific radioactivity concentrations in the coal fly ash obtained from heat producing stations in Korea were analyzed and its radiological hazard for reuse in construction purpose was evaluated. The concentrations of uranium isotopes in the real fly ash measured by TBP solvent extraction method and $\alpha$-spectrometer were found to be about 116.1 Bq $kg^{-1}$ for $^{238}U$, 5.01 Bq $kg^{-1}$ for $^{235}U$, and 121.2 Bq $kg^{-1}$ for $^{234}U$, respectively. The activity ratio of $^{234}U/^{238}U$, in the coal fly ash was in $1.04\;{\pm}\;0.03$, which is similar to that of uncontaminated Korean soil in natural conditions (1.14). The specific radioactivities of $^{226}Ra,\;^{232}Th,\;and\;^{40}K$ in the coal fly ash were also determined using $\gamma$-spectrometer with a HPGe detector The results showed that $^{226}Ra,\;^{232}Th,\;and\;^{40}K$ in the coal fly ash were in concentrations of $101.7{\sim}113.9$, $39.5{\sim}54.2\;and\;315.0{\sim}990.6$ Bq $kg^{-1}$, respectively. With the specific radioactivities obtained from $\gamma$-spectrometric measurements of the coal fly ash, its radiological hazard for reuse was evaluated. The result showed that the radioactivity of the coal fly ash was in permissible level.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.111-114
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• 2010

Purpose: There has been recent interest in the radioactivity uptake and image acquisition of radioactivity concentration. The degree of uptake is strongly affected by many factors containing $^{18}F$-FDG injection volume, tumor size and the density of blood glucose. Therefore, we investigated how radioactivity uptake in target influences 2D or 3D image analysis and elucidate radioactivity concentration that mediate this effect. This study will show the relationship between the radioactivity uptake and 2D,3D image acquisition on radioactivity concentration. Materials and Methods: We got image with 2D and 3D using 1994 NEMA PET phantom and GE Discovery(GE, U.S.A) STe 16 PET/CT setting the ratio of background and hot sphere's radioactivity concentration as being a standard of 1:2, 1:4, 1:8, 1:10, 1:20, and 1:30 respectively. And we set 10 minutes for CT attenuation correction and acquisition time. For the reconstruction method, we applied iteration method with twice of the iterative and twenty times subset to both 2D and 3D respectively. For analyzing the images, We set the same ROI at the center of hot sphere and the background radioactivity. We measured the radioactivity count of each part of hot sphere and background, and it was comparative analyzed. Results: The ratio of hot sphere's radioactivity density and the background radioactivity with setting ROI was 1:1.93, 1:3.86, 1:7.79, 1:8.04, 1:18.72, and 1:26.90 in 2D, and 1:1.95, 1:3.71, 1:7.10, 1:7.49, 1:15.10, and 1:23.24 in 3D. The differences of percentage were 3.50%, 3.47%, 8.12%, 8.02%, 10.58%, and 11.06% in 2D, the minimum differentiation was 3.47%, and the maximum one was 11.06%. In 3D, the difference of percentage was 3.66%, 4.80%, 8.38%, 23.92%, 23.86%, and 22.69%. Conclusion: The difference of accumulated concentrations is significantly increased following enhancement of radioactivity concentration. The change of radioactivity density in 2D image is affected by less than 3D. For those reasons, when patient is examined as follow up scan with changing the acquisition mode, scan should be conducted considering those things may affect to the quantitative analysis result and take into account these differences at reading.

• Analytical Science and Technology
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• v.17 no.6
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• pp.514-519
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• 2004

Soil samples collected from around the BOMARC Missile Site were measured for their activity concentrations and isotopic ratios of Pu and Am isotopes with particle sizes. The activity concentrations of Pu and Am in the BOMARC soil were remarkably higher than the fallout levels, and the activities decreased nearly exponentially with an increasing particle size of the soil due to a decreasing surface area. The activity ratios of Pu-238 / Pu-239, 240, Pu-241 / Pu-239, 240 and Am-241 / Pu-239, 240 observed in the BOMARC soil were much lower than those attributed to the nuclear reprocess plants and the Chernobyl fallout. Also, the atomic ratio of Pu-240 / Pu-239 in the BOMARC soil was remarkably lower than the fallout value influenced by the nuclear weapons testing and the Chernobyl accident. The atomic ratio of Pu-240 / Pu-239 was so close to the value of the weapons grade Pu released from the crash of a B52 plane in the Thule of the Greenland, such that the Pu isotopes detected in the BOMARC soil could have originated from the weapons grade plutonium.

• Journal of Radiation Protection and Research
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• v.20 no.2
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• pp.123-128
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• 1995

The concentration of Cs-137 and Sr-90 has been analyzed in soils around Taejon region. A correalation was found between the concentration of Cs-137 and the organic matter content. The mean value of Cs-137 was 14.37Bq/kg-dry and that of Sr-90 was 7.95Bq/kg-dry in undisturbed soils around Taejon region. The concentration ratio of Cs-137/Sr-90 was 1.99. The distribution of Cs-137 and Sr-90 was similar to cumulative fallout level and had been more affected by nuclear weapons test than by the chernobyl accident.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11b
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• pp.583-589
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• 1996

원자력발전소에서 발생되는 방사성폐기물들은 폐기물형태 및 방사능 농도가 다양하며 영구처분장으로 이송전까지는 발전소내의 임시 저장고에 안전하게 보관, 관리하고 있다. 생성된 폐기물드럼내에는 감마방출핵종을 비롯하여 알파 및 베타방출 핵종들이 균질 또는 비균질하게 존재하고 있으며 방사능의 세기나 폐기물의 특성에 따라 안정화시키거나 압축처리하여 드럼에 담겨져 있기 때문에 일반적인 파괴분석에 의한 화학분석법으로는 작업자의 피폭, 시료의 대표성 선정 및 장시간의 화학처리 시간소요 등으로 핵종분석이 곤란하다. 따라서 본 논문은 일반적으로 감마핵종분석시 흔히 사용하고 있는 고순도게르마늄(HPGe) 검출기를 이용하여 드럼의 감마핵종농도를 분석하는 방법과 장치의 개발에 대해 언급하였으며 알파나 베타핵종과 같이 직접 분석이 곤란한 핵종들은 각 폐기물드럼내에 존재하는 Co-60이나 Cs-137과의 상관관계를 미리 예측한 척도인자 (scaling factor)를 이용하여 간접적으로 구하는 방법을 사용하고 있으나 본 논문에서는 드럼으로부터 감마핵종만을 분석하는 방법에 대해서만 언급하였다. 또한 핵종분석시스템의 최적 운전조건을 도출하기 위해 드럼회전테이블의 속도결정 및 모의드럼을 이용한 방사능측정 등을 통해 핵종 농도 분석시의 오차를 30% 이내로 유지할 수 있었다.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.59-59
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• 1993

비방사능물질인 Biotin을 DNA probe에 표지하여 nonisotopic hybridization 방법을 사용하여 감도를 높임으로써, 손쉽게 생물공학 의약품의 품질관리에 사용되도록 하였다. Bethesda Research Laboratories(BRL) 회사 제품인 biotinylated probes-avidin alkaline phosphatase를 이용한 chemiluminescene detection방법으로 행하여 λ phage DNA, yeast DNA, E.coil DNA의 한계 검출 농도를 알아내고, 생물 공학 제품에 적용하였다. Dot blot hybridization 방법으로 행하여 λ phage DNA는 0.1pg, Yeast DHA는 4.5pg, E. coli DNA는 8.9pg까지 검출되었고, 기존 생물공학 제품에서는 숙주 유래 DNA가 전혀 검출되지 않았다.

• Journal of Radiation Protection and Research
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• v.18 no.1
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• pp.9-24
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• 1993

The time-dependent radioecological model applicable to Korean environment has been developed in order to assess the radiological consequences following the short-term deposition of radionuclides in an accident of nuclear power plant. Time-dependent radioactivity concentrations in foodstuffs can be estimated by the model called 'KORFOOD' as well as time-dependent and time-integrated ingestion doses. Three kinds of critical radionuclides and thirteen kinds of foodstuffs were considered in this model. Dynamic variation of radioactivities were simulated by considering several effects such as deposition, weathering and washout, resuspension, root uptake, translocation, leaching, senescence, intake and excretion of soil by animals, intake and excretion of feedstuffs by animals, etc. The input data to the KORFOOD are the time of the year when the deposition occurs, the kinds of radionuclides and foodstuffs for estimation. The time-dependent specific activities in rice and the ingestion doses due to the consumption of all considered foodstuffs were calculated with deposition time using agricultural data-base in Kori region. In order to validate results of KORFOOD, the calculated results were compared with those by a leading German model, ECOSYS-87. The comparison of results shows good agreements within a factor of ten.

• Journal of the Korean Society of Radiology
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• v.8 no.6
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• pp.293-299
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• 2014

Compton suppression device is a device by using the Compton scattering reaction and suppress the Compton continuum portion of the spectrum, so can be made more clear analysis of gamma ray peak in the Compton continuum region. Measurements above background occurs or, radioactivity counts of radioactivity concentration value of $^{40}K$ nuclides $^{137}Cs$ and natural radioactivity artificial radioactivity detected from the surface soil sample, unwanted non-target analysis and interference peak who dotted line you know the calibration of the measurement energy is allowed to apply the (Compton suppression) non-suppressed spectrum inhibition spectrum and (Compton Unsuppression) the background to the measured value of the activity concentration value of the standard-ray source is detected relative to the peak of By measuring according to the different distances cause $^{137}Cs$, and comparative analysis of the Monte Carlo simulation, in order to obtain a detection capability for efficient, looking at the Compton inhibitor, as the CSF value increases with increase in the distance, more It was found that the background due to Compton continuum of the measured spectrum suppression mode Compton unrestrained mode can know that the Compton suppression many were made, using a $^{137}Cs$ is reduced.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.4
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• pp.245-251
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• 2004

Soil washing equipment was developed for decontamination of radioactively contaminated soil generated during normal operation or decommissioning and verification experiments were performed. Decontamination effciency above $80{\%}$ was achieved. In case of low radiation level and large particle size, decontamination efficiency was higher. According to the ratio of volume of water to soil quantity, decontamination efficiency was higher in case of high radiation level. Re-decontamination using decontaminated soil was effective in case of small particles. Using soil washing equipment, radioactivity of contaminated soil generated in nuclear power plant can be decreased and volume of soil for disposal can be decreased. And this equipment can be used in decommissioning.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4819-4825
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• 2010

In all of dental ceramics, these materials contained the radio-isotopes with natural abundance ratio. After dental treatment, remained dental ceramics in the oral cavity is caused for human internal dose. In this study, the gross beta activity levels were measured in dental materials including 22 dental ceramics, 1 resin, and 2 cements for estimation of human internal dose. In dental ceramic samples, the obtained results showed that the gross beta activity level varied between 1.317 ~ 2.935 Bq/g and the gross beta activity level was 2.379 Bq/g. And the same level for dentine, opacious dentine, translucent and enamel were 2.479 Bq/g, 2.491 Bq/g, 2.470 Bq/g and 2.069 Bq/g, respectively. The gross beta activity level of temporary resin and cements were negligible, compare to the same level of dental ceramics. The high gross beta activity level observed in opacious dentine code OD-A4 is 2.935 Bq/g thus mainly ascribable to 40K. The reduction of the radiation level of natural radio-isotopes and the improvement of the dental ceramic materials should be required for internal dose reduction.