• 한국항공우주학회지
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• 제32권5호
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• pp.84-90
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• 2004

양성자 가속기를 이용한 지상 실험에 기초하여 인공위성에서 사용할 마이크로프로세서의 SEE 발생률을 예측하였다. 우주 공간의 하전 입자 분포를 AP8, JPL91 그리고 CREME 모델을 사용하여 추정하고, 양성자 가속기를 통한 실험에서 얻어진 단면적 곡선들을 SEE 발생률 예측에 사용하였다. 약 685 km의 저궤도에 대해 고 경사각과 저 경사각이 고려되었다. 계산 결과는 후보 소자에 대한 SEE 발생률이 저 경사각에서는 수용할만한 것이었지만 고 경사각의 경우에는 최악의 조건에서 문제될 수 있음을 보여준다.

• 한국항공우주학회지
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• 제32권5호
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• pp.116-121
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• 2004

사이클로트론 가속기를 이용한 양성자 우주환경의 모사시험이 수행되었다. 모사시험에 사용된 사이클로트론은 양성자를 약 $10^6-10^8\;protons/cm^2/s$의 선속에서 200 MeV까지 가속 할 수 있다. 가속된 양성자는 우주에서 사용될 MPC860 소자에 입사되었으며, 양성자 조사에 의한 소자의 누적 반응과 순간 반응이 모두 관찰되었다. 주된 순간 반응은 저장된 데이터의 변화였으나, 간헐적인 기능 정지 현상도 관찰되었다. 누적 반응은 소자 내에서 소모되는 전류의 증가로 나타났다.

• 한국안전학회지
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• 제23권5호
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• pp.73-78
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• 2008

The fire hazards and combustion heat of puzzle mats in group day care home were analysed using variable external irradiation level. The fire hazards such as ignition time, ignition temperature, mass loss rate, and flame temperature profile were measured. Incident heat fluxes of $15kW/m^2$, $20kW/m^2$, $25kW/m^2$, $35kW/m^2$, $50kW/m^2$ and $75kW/m^2$ were selected for these experiments. All samples were tested in the horizontal orientation and were wrapped in a single layer of aluminium foil. Each sample was nominally 20mm thick and 100mm square. Five samples of puzzle mat were tested in the study : Type A, B, C, D and E. Type A, B and C are all general grades whereas Type D and E are both Flame retardant grades. As results, Type E of FR-grade showed the best characteristics in safety of the early fire from ignition time, critical heat flux, and ignition and flame temperature data of this study. All specimen of G-grade(Type A, B and C), however, showed the weak in safety of fire.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.330-338
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• 2016

The U-Zr or U-TRU-Zr cylindrical metallic fuel slug used in fast reactors is known to swell significantly and to grow during irradiation. In neutronics simulations of metallic-fueled fast reactors, it is assumed that the slug has swollen and contacted cladding, and the bonding sodium has been removed from the fuel region. In this research, a realistic burnup-dependent fuel-swelling simulation was performed using Monte Carlo code McCARD for a single-batch compact sodium-cooled breed-and-burn reactor by considering the fuel-swelling behavior reported from the irradiation test results in EBR-II. The impacts of the realistic burnup-dependent fuel swelling are identified in terms of the reactor neutronics performance, such as core lifetime, conversion ratio, axial power distribution, and local burnup distributions. It was found that axial fuel growth significantly deteriorated the neutron economy of a breed-and-burn reactor and consequently impaired its neutronics performance. The bonding sodium also impaired neutron economy, because it stayed longer in the blanket region until the fuel slug reached 2% burnup.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.255-261
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• 2022

A reliable and well-characterized dosimetry system which is traceable to the international measurement system, is the key element to quality assurance in radiation processing with cobalt-60 gamma rays, X-rays, and electron beam. This is specifically the case for health-regulated processes, such as the radiation sterilization of single use medical devices and food irradiation for preservation and disinfestation. Polyethylene is considered to possess a lot of interesting dosimetric characteristics. In this work, a detailed study has been performed to determine the dosimetric characteristics of a commercialized high-density polyethylene (HDPE) film using Fourier transformed infrared spectrometry (FTIR). Correlations have been established between the absorbed dose and radiation induced infrared absorption in polyethylene having a maximum at 965 cm^-1 (transvinylene band) and 1716 cm^-1 (ketone-carbonyl band). We have found that polyethylene dose-response is linear with dose for both bands up to1000 kGy. For transvinylene band, the dose-response is more sensitive if irradiations are made in helium. While, for ketone-carbonyl band, the dose-response is more sensitive when irradiations are carried out in air. The dose-rate effect has been found to be negligible when polyethylene samples are irradiated with electron beam high dose rates. The irradiated polyethylene is relatively stable for several weeks after irradiation.

• Radiation Oncology Journal
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• 제6권2호
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• pp.247-251
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• 1988

1987년 8월부터 1988년 월까지 가톨릭의대 부속 성모병원 방사선과에서는 20명의 급성 백혈병 환자와 만성과립성 백혈병 환자를 6MV선형가속기를 사용하여 전신조사 하였다. 20명의 환자 중 8명은 총 방사선량 1200cGy책 1회 방사선 조사를 받았다. 나머지 2명 중 1명은 4회 분할 조사로 총 850cGy를 받았으며, 다른 1명은 2회 분할 조사하여 총 1100cGy를 받았다. 이식편은 20명중 17명이 동종 이식편을 받았고, 2명이 자가 이식편을 받았으며, 오직 1명만이 부적합 이식편을 받았다. 현재 13멍이 생존해 있고, 7명이 사망했으며, 전신조사에 의한 합병증은 설사, 점막염증, 구토와 구역, 피부발진 등의 순으로 나타났다.

• Radiation Oncology Journal
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• 제26권3호
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• pp.173-180
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• 2008

목 적: 치사선량의 방사선에 의해 유도되는 아포토시스에 대해 항산화제 또는 산화제로 알려진 EGCG가 어떤 효과를 나타내는지를 마우스 비장에서 연구하였다. 대상 및 방법: C57BL/6 마우스를 실험군에 따라 정상대조군, 방사선조사 단독군, EGCG 전처치군(방사선조사 1시간 전에 100 mg/kg 복강주사)으로 분류하고 7 Gy의 단일선량으로 전신조사 하였다. 각 실험군별 비장 내의 아포토시스는 TUNEL assay를 통해 분석하였고, Bax와 Bcl-2 유전자 발현은 Western blotting 방법으로 측정하였다. 결 과: 비장 내 아포토시스는 주로 white pulp에만 국한되어 발견되었으며, 방사선조사 후 8시간째에 최대의 아포토시스지수를 나타냈다. 8시간째에 방사선조사 단독군과 EGCG 전처치군의 아포토시스지수는 53.9%와 52.1%로 유의한 차이를 보이지 않았다(p=0.328). 또한 두군간에 Bax/Bcl-2 ratio (1.64 vs 0.97, p=0.037)와 대조군에 상대적인 Bcl-2 단백질 발현(0.57 vs 0.82, p=0.037)에서는 유의한 차이를 보였으나, Bax 발현(0.86 vs 0.81, p=0.335)에서는 차이를 보이지 않았다. 결 론: 마우스 비장세포에서 EGCG가 방사선에 의해 유도되는 아포토시스를 유의하게 감소시키지 못하였고, 추가적인 아포토시스의 증가를 유발하지도 않았다.

• 치과방사선
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• 제23권1호
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• pp.27-44
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• 1993

This study was performed to investigate the changes of mandibular condyle by low calcium diet and the effects of irradiation on the bone in osteoporotic state. In order to carry out this experiment, 80 seven-week old Sprague-Dawley strain rats weighing about 150 gm were selected and equally divided into one experimental group of 40 rats and one control group with the remainder. The experimental group and the control group were then subdivided into two group and exposed to irradiation. The two irradiation groups received a single dose of 20 Gy on the jaw area only and irradiated with a cobalt-60 teletherapy unit. The rats in the control and experimental groups were serially terminated by fours on the 3rd, the 7th, the 14th, and the 21st day after irradiation. After termination, both sides of the dead rats mandibular condyle were removed and fixed with 10% neutral formalin. The bone mineral density of mandibular condyle was measured by use of dual energy X-ray bone densitometer(model DDX-alpha, Lunn Corp., U. S. A.). The mandibular condyle was radiographed with Hitex HA-80(Hitex Co., Japan). Thereafter, the obtained radiographs were observed, and the mandibular condyle was further decalcified and embedded in paraffin as the general method. The specimen sectioned and stained with hematoxylin-eosin, PAS and Rabbit Anti-Human Tumor Necrosis Factor-a observed by a light microscope. The obtained results were as follows: 1. In the non-irradiated group with the low calcium diet, the bone mineral density of the condyle was markedly decreased after 14 days, and decrease the number of trabeculae of the condyle and resorption of the calcified cartilaginous zone were observed after 3 days. On microscopic observations, the number nd size of trabeculae were decreased after 7 days of experiment. 2. In the irradiated group with the low calcium diet, the bone mineral density of the condyle was markedly decreased after 14 days and resorption of the calcified cartilaginous zone and decrease the number and coarse of the trabeculae of the condyle were observed. These findings were extended rather than in non-irradiated group with low calcium diet. On microscopic observations, many osteoclasts were detected and the number and size of trabeculae were somewhat decreased after 7 days. Also there was degenerative changes of tissues of bone marrow on the 14th day but that condition was restored on the 21st day of experiment. 3. In the irradiated group with normal diet, the bone mineral density of the condyle was somewhat decreased with times and degree of decrease of the number of trabeculae was somewhat larger than in the non-irradiated group with normal diet. On microscopic observations, the tissues of bone marrow were atrophic and degenerative changes but that condition was restored on the 21st day of experiment. 4. In immunocytochemical findings, in the irradiated and non-irradiated groups with low calcium diet, negative or partial positive response to TNF was observed, but positive response in the normal diet groups.

• 한국동물학회지
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• 제11권2호
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• pp.48-54
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• 1968

成熱한 albino 雄性 흰쥐를 對照群과 實驗群으로 나누어 對照群에는 0.9% 生理食鹽水를, 實驗群에는 methylene blue (40mg/kg, 食鹽水에 溶解, pH 7.0)를 各各 皮下注射處理하였다. 30 分後에 兩群共히 每分當 33r 으로 總線量 300r 의 X-線을 一時 全身照射하였다. 照射後 24日間에 걸쳐 肝臟 glycogen 含量(Carroll et al. 方法), 血糖含量(Folin and Wu 方法) 및 K 와 Na 含量(flame photometer)과 Cl 含量(automatic chloride titrator)을 各各 測定하여 methylene blue의 放射線에 對한 防禦　果를 硏究調査하였다. 一般的으로 肝臟 glycogen 含量은 兩群共히 X-線照射直後 若干 減少하나 1 日區에서부터 急激한 增加를 나타내고 있으며 特히 實驗群인 methylene blue 處理群에서는 對照群인 生理食鹽水群에 比하여 增加의 遲滯性을 나타내었다. 血糖含量에 對해서는 兩群모두 X-線 照射直後 若干 減少하는 傾向을 보였으나 時日經過에 따라서 서서히 增加하며 特히 實驗根인 methylene blue 處理群은 對照群인 生理食鹽水에 比하여 增加에 遲滯性을 나타내었다. 또한 血液內 電解質含量에 있어서 K, Na 및 Cl 含量은 一般的으로 兩群모두 時日經過에 따라 큰 變化는 없었으나 特히 K와 Na의 含量은 初期狀態에서 若干의 變化가 있었고 Cl 에서는 別變化를 觀察할 수 없는것으로보아 methylene blue가 血液內 電解質含量에는 別影響이 없었다. 以上의 結果로 미루어 보아 炭水化物代謝에 있어서 methylene blue가 放射線에 對한 防禦　果가 있는 것으로 思料된다.

• Applied Microscopy
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• 제23권2호
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• pp.11-26
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• 1993

This experiment was performed to study the morphological responses of the pigment epithelial cell and the Bruch's membrane of the retina of rat following X-ray irradiation. Male rats were divided into normal and experimental groups. The heads of the rats, under sodium thiopental anesthesia, were exposed to 3,000 rads or 6,000 rads of radiation in a single dose, respectively. The source was a Mitsubishi Linear Accelerator ML-4MV. The target to skin distance was 80cm, and the. dose rate was 200 rads/min. The experimental groups were sacrificed on the 6th hour, 2nd and 6th day after X-ray irradiation. Under anesthesia, 1% glutaraldehyde-1% paraformaldehyde solution(0.1M Millonig's phosphate buffer, pH 7.3) was perfused through the left ventricle and ascending aorta. Pieces of the tissue taken from the posterior region of the retina were fixed in 2.5% glutaraldehyde-1.5% paraformaldehyde(0.1M Millonig's phosphate buffer, pH 7.3) and 1% osmium tetroxide(0.1M Millonig's phosphate buffer, pH7.3), and embedded in araldite mixture. The ultrathin sections contrasted with uranyl acetate and lead citrate were observed with JEM 100 CX-II electron microscope. The results were as follow; 1. The morphological changes of the pigment epithelial cells were not pronounced after exposure to 3,000 rads of X-ray. But on the 6th hour after exposure to 6,000 rads of X-ray, bulging nuclear membrane protruding into the cytoplasm and nuclear chromatin clumped into numerous masses along the nuclear membrane were observed. At the 2nd and 6th day post-irradiation, partial cytolysis or necrosis were seen. 2. The thickness of the Bruch's membrane of the experimental groups were increased in the time and dose range covered by this study, and splitting or diffusing basal laminae of the choriocapillary layer were observed frequently in the experimental group. Above results suggest that large amount(6,000 rads) of head irradiation induce direct hazardous effects on the pigment epitherial cells and Bruch's membrane of the retina of the rat, but pigment epithelial cells are more radioresistant than Bruch's membrane.