• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.523-530
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• 2005

In this study, maximum exposure rate at DAW(Dry Active Waste) drum surface which is satisfying regulation limit was calculated for conceptual design of IP(Industrial Package). DAW can be classified as combustible and non-combustible waste and the calculation was conducted for single and mixed radionuclide for each type of waste. In case of combustible waste that mixed radionuclide is uniformly distributed, the maximum exposure rates at drum surface were 3.60E-01, 8.85E-01 and 1.27E+01 mSv/hr for IP Type 1, 2-a and 2-b, respectively. and 3.60E-01, 8.85E-01, 1.27E+01 mSv/hr for single radionuclide(Co-60). In case of non-combustible waste that mixed radionuclide is uniformly distributed, the maximum exposure rates at drum surface were 7.14E-01, 1.83E+00, 2.69E+01 mSv/hr for IP Type 1, 2-a and 2-b, respectively. and 7.13E-01, 1.81E-01, 2.62E+01 mSv/hr for single radionuclide(Co-60). Through this study, the maximum amount of DAW can be transported by IP was suggested as maximum exposure rate at drum surface and the calculation for the other types of waste will be conducted.

• Journal of radiological science and technology
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• v.39 no.2
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• pp.237-246
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• 2016

This study is therefore aimed at measuring the surface dose rate and the spatial dose rate in and outside the radionuclide facility in order to ensure safety of the patients, radiation workers and family care-givers in their use of such equipment and to provide a basic framework for further research on radiation protection. The study was conducted at 4 restrooms in and outside the radionuclide facility of a general hospital in Incheon between May 1 and July 31, 2014. During the study period, the spatial contamination dose rate and the surface contamination dose rate before and after radiation use were measured at the 4 places-thyroid therapy room, PET center, gamma camera room, and outpatient department. According to the restroom use survey by hospitals, restrooms in the radionuclide facility were used not only by patients but also by family care-givers and some of radiation workers. The highest cumulative spatial radiation dose rate was 8.86 mSv/hr at camera room restroom, followed by 7.31 mSv/hr at radioactive iodine therapy room restroom, 2.29 mSv/hr at PET center restroom, and 0.26 mSv/hr at outpatient department restroom, respectively. The surface radiation dose rate measured before and after radiation use was the highest at toilets, which are in direct contact with patient's excretion, followed by the center and the entrance of restrooms. Unsealed radioactive sources used in nuclear medicine are relatively safe due to short half lives and low energy. A patient who received those radioactive sources, however, may become a mobile radioactive source and contaminate areas the patient contacts-camera room, sedation room, and restroom-through secretion and excretion. Therefore, patients administered radionuclides should be advised to drink sufficient amounts of water to efficiently minimize radiation exposure to others by reducing the biological half-life, and members of the public-family care-givers, pregnant women, and children-be as far away from the patients until the dose remains below the permitted dose limit.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.2
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• pp.73-80
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• 2011

The radiation shielding analysis for a Burnup-credit (BUC) cask designed under the management of Korea Radioactive Waste Management Corporation (KRMC) was performed to examine the contribution of each radiation source affecting dose rate distribution around the cask. Various radiation sources, which contain neutron and gamma-ray sources placed in active fuel region and the activation source, and imaginary nuclear fuel were all considered in the MCNP calculation model to realistically simulate the actual situations. It was found that the maximum external and surface dose rates of the spent fuel cask were satisfied with the domestic standards both in normal and accident conditions. In normal condition, the radiation dose rate distribution around the cask was mainly influenced by activation source ($^{60}Co$ radioisotope); in another case, the neutron emitted in active fuel region contributed about 90% to external dose rate at 1m distance from side surface of the cask. Besides, the contribution level of activation source was dramatically increased to the dose rates in top and bottom regions of the cask. From this study, it was recognized that the detailed investigation on the radiation sources should be performed conservatively and accurately in the process of radiation shielding analysis for a BUC cask.

• Progress in Medical Physics
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• v.16 no.2
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• pp.77-81
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• 2005

To determine the appropriate method out of various available methods to measure build-up doses, the measurements and comparisons of depth doses of build-up region including the surface dose were executed using the Attix parallel-plate ionization chamber, the Markus chamber, a cylindrical ionization chamber, and a diode detector. Based on the measurements using the Attix chamber, discrepancies of the Markus chamber were within $2\%$ for the open field and increased up to $3.9\%$ in the case of photon beam containing the contaminant electrons. The measurements of an cylindrical ionization chamber and a diode detector accord with those of the Attix chamber within $1.5\%\;and\;1.0\%$ and after those detectors were completely immersed in the water phantom. The results suggest that the parallel-plate chamber is the best choice to measure depth doses in the build-up region containing the surface, however, using cylindrical ionization chamber or diode detector would be a reasonable choice if no special care is necessary for the exact surface dose.

• Progress in Medical Physics
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• v.15 no.1
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• pp.39-44
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• 2004

The energy distributions for clinically used electron beams from measured and calculated mono energetic depth dose values were calculated. The energy distributions having the minimum difference between the measured and reduced values of depth dose are determined by iterations based on least square method. The nominal energies of 6, 9, 12, 15 MeV clinical electron beams were examined. The Monte Carlo depth dose calculations with determined energy distributions were peformed to evaluate those distributions. In a comparison of the calculated and measured depth dose data, the standard errors are estimated within $\pm$ 3% from surface to R$_{80}$ depth and within $\pm$4% from the surface to near the range for all electron beams. This can be practically applied to determine the energy distributions for clinically used electron beams.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.239.2-239.2
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• 2011

치과재료의 개발은 치과 치료 기술에 있어서 가장 중요한 요소이며, 현재 일반화되고 있는 치과 치료 기술 중 하나가 임플란트 시술이다. 임플란트의 기술 개발은 주로 임플란트 나사의 표면개질을 통한 기능개선에 초점을 ��추어 진행되어지고 있다. 본 연구에서는 Ti 임플란트 표면상에 양극산화법을 적용하여 다양한 지름 및 기공 크기를 갖는 $TiO_2$ 나노튜브를 제조하여 전자빔 조사를 통한 표면개질시 그 특성에 관한 연구를 수행하였다. 특히 전자빔 조사가 Ti/$TiO_2$ 나노튜브 표면상에 존재 가능한 조골세포의 성장 특성에 미치는 영향을 연구하였다. 양극산화법을 이용한 Ti/$TiO_2$ 나노튜브는 전해질로서 HF와 $NH_4F$를 사용하였으며, 20-80 V의 인가 전압하에서 내경 약 80 nm, 외경 약 124 nm 및 길이 약 280 nm-14 ${\mu}m$의 비교적 균질한 지름 및 분포를 갖는 Ti/$TiO_2$ 나노튜브를 제조하였다. 전자빔 조사는 EB-Tech (대전, 한국)의 electron-beam accelerator(Model ELV-4)를 이용하였으며, 1.0 MeV의 빔 에너지로 총 흡수선량이 50 kGy, 500 kGy 및 5,000 kGy로 조사하였다. 전자빔을 조사하기 전 후 Ti/$TiO_2$ 나노튜브 표면상에 조골세포주(Osteoblast cell)의 배양시간의 변화에 따른 효과를 연구한 결과 배양 전 후 전자빔 조사선량의 증가에 따라 조골세포의 흡착률이 증가함을 확인할 수 있었다. 특히 HF전해질을 이용한 $TiO_2$ 나노튜브의 경우 5,000 kGy 조사선량의 전자빔을 조사한 후 조골세포 흡착률이 약 160% 증가하는 결과를 얻을 수 있었다. 전자빔 조사 전 후 조골세포 흡착률의 변화원인은 전자빔 조사 유무에 따른 $Ti^{3+}$와 $Ti^{4+}$의 변화에 기인함을 규명하였다. 이러한 결과는 향후 임플란트용 Ti/$TiO_2$ 나노튜브의 표면 개질시 전자빔의 유용성을 제시한다고 할 수 있다.

• Journal of Radiation Protection and Research
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• v.32 no.1
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• pp.1-8
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• 2007

A model for radiological dose assessment in an urban environment, METRO-K has been developed. Characteristics of the model are as follows ; 1) mathematical structures are simple (i.e. simplified input parameters) and easy to understand due to get the results by analytical methods using experimental and empirical data, 2) complex urban environment can easily be made up using only 5 types of basic surfaces, 3) various remediation measures can be applied to different surfaces by evaluating the exposure doses contributing from each contamination surface. Exposure doses contributing from each contamination surface at a particular location of a receptor were evaluated using the data library of kerma values as a function of gamma energy and contamination surface. A kerma data library was prepared fur 7 representative types of Korean urban buildings by extending those data given for 4 representative types of European urban buildings. Initial input data are daily radionuclide concentration in air and precipitation, and fraction of chemical type. Final outputs are absorbed dose rate in air contributing from the basic surfaces as a function of time following a radionuclide deposition, and exposure dose rate contributing from various surfaces constituting the urban environment at a particular location of a receptor. As the result of a contaminative scenario for an apartment built-up area, exposure dose rates show a distinct difference for surrounding environment as well as locations of a receptor.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.1
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• pp.11-15
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• 2008

In order to transport spent resin in a high integrated container made of high density polyethylene, a method for determining transportation grade by radioactivity analysis was developed. Ratios of radioisotopes in spent resin were derived from radioactivity analysis on spent resin. Associated curie-to-dose factors were determined to estimate radioisotope inventory from surface dose rates of spent resin. From the results, Activity limit of type A package was derived to be 1.19 TBq for HIC, and the corresponding surface dose rate was found to be 124.2 mSv/h.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.90-90
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• 2000

이온빔을 이용한 리소그래피의 경우 미크론 이하의 미세구조를 형성할 수 있는 유용한 수단으로서 방사광 X-선과 함께 주목을 받고 있으며, 이와 같은 미세구조 제작은 MEMS (Micro Electro-Mechanical System) 개발에 있어서 매우 중요하다. 그러나 이온빔을 이용한 리소그래피에 대한 연구가 많이 이루어져 있지 않은 상태이다. MeV급 양정사 빔을 이용한 리소그래피의 가능성을 확인하기 위하여 기본적인 실험을 수행하였으며, 최적 이온빔 조사 조건 및 최적 현상 조건을 도출하였다. Resist로는 PMMA를 사용하였으며, 1.8 MeV 양성자 빔을 사용하여 50$\mu\textrm{m}$ 깊이의 구조물을 만들었다. 1.8MeV 양성자 빔의 조사선량이 7x1013ions/cm2 이상이 되면 PMMA 내부에 기포가 형성되므로 적정 조사선량을 4x1013 ions/cm2으로 결정하였다. 또한 선량을 4x1013ions/cm2 으로 고정하고 선량률을 변화시켜주면 선량률이 8x1011ions/cm2S 일 때부터 시료에 기포나 터짐 현상 등의 문제가 발생하였으며 5x1010~~1x1010ions/cm2s 의 선량률이 조사시간, 결함측면에서 가장 적합한 영역임을 알 수 있었다. 현상제로는 20% morpholine, 5% etanolamine 60% diethylenglykol-monobutylether, 15% 증류수를 혼합하여 사용하였다. 현상 온도를 30~5$0^{\circ}C$로 변화시켜서 현상을 한 결과, 4$0^{\circ}C$에서 현상 소요시간은 1시간 이내이며 SEM으로 관찰된 표면의 상태도 제일 양호한 결과를 보였다. 82 mesh 밀도, 선굵기 60$\mu\textrm{m}$, 크기 20x20 mm인 백금 망을 마스크로 사용하여 실제 3차원 미세구조를 제작하여 보았다. 그림 1에서 제작된 구조물의 SEM 사진을 보여주었으며, 식각된 면의 조도가 매우 뛰어나며 모서리의 직각성도 우수함을 확인할 수 있다. 이와 같이 도출된 시험 조건을 기초로 하여 리소그래피 후에 전기 도금을 이용한 금속 몰드 제작 및 이온빔 리소그래피 장점을 최대한 살릴수 있는 미세구조 제작에 대한 연구를 계속 추진할 계획이다.

• Progress in Medical Physics
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• v.13 no.2
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• pp.98-103
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• 2002

The purpose of this study was to evaluate the absorbed dose to the coronary artery segment from various sized balloon angio catheters. The liquid form of Ho-166 was produced at the KAERI by (n, ${\gamma}$ ) reaction. We used GafChromic film for the estimation of the absorbed dose by beta particles. The exposed films were read using a videodensitometer. Several film exposures were made with varying irradiation times and activities. A modified micrometer was used for the measurement of the absorbed dose distribution near the balloon surface. Four balloons of coronary catheters evaluated were 30 m long and 2.5, 3.0, 3.5 and 4.0 mm in diameter. All doses are plotted in units of Gy/min/GBq/ml as a function of radial distance in mm from the surface of balloon. The absorbed dose rate was 0.86, 1.01, 1.11 and 1.24 Gy/min/GBq/ml at a balloon surface for various balloon diameter 2.5, 3.0, 3.5 and 4.0 mm respectively. Using a vacuum pump, the air in the balloon was evacuated prior to instillation of the Ho-166 source. By removing air bubbles in the balloon, the absorbed dose distribution was more uniform.