• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1788_1789
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• 2009

본 논문에서는 핵폭발과 같은 고준위방사선환경에서의 전자부품소자의 피해평가분석을 통하여 군용전자장비의 내방사선화를 하기 위한 기반기술의 확립을 위한 연구의 일환으로 74AC04(Inverter) IC에 대한 고준위감마선조사시험을 통하여 Co-60 Gamma-ray 선원을 사용하여 총 400Krad[si] 누적 선량에 대한 74AC04 소자의 동작특성 및 전기적 파라메터의 변화분석을 진행하였다. 시험평가 방법 및 절차는 MIL-STD-883G 1019.7[1] 및 ESA/SCC Basic Specification No.22900[2] 절차를 기준으로 하여 동일 lot에 대한 5개의 샘플을 이용하여 동작특성에 영향을 미치는 주요한 전기 적파라메터인 정지소비전류, 입력누설전류, VIL(Maximum Low Level Input Voltage)에 대한 변화추이를 분석하였다. 이번 조사시험을 통하여 입력게이트에서의 누적선량에 따른 TID(Total Ionizing Dose) 효과로 인한 VIL의 감소 추이를 확인 할 수 있었으며 총 누적선량 160Krad 이상에서의 VIL은 허용기준치이하로 감소하였고 정지소비전류의 경우 누적선량에 따른 점진적 증가 현상과 200Krad부근에서의 설계스펙허용치를 초과하는 결과를 확인하였다.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1282-1288
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• 2020

In the first study, the Radon emanation and radiological hazards associated with radionuclides in soil samples, collected from 9 various date palm farms located in 3 different districts in Saudi Arabia were determined through a high purity Germanium (HPGe) gamma-ray spectrometer. The estimated average values of Radon emanation coefficient and Radon mass exhalation rate for soil samples were 0.535 ± 0.016 and 50.063 ± 7.901 mBqkg^-1h^-1, respectively. The annual effective dose of radionuclides in all sampling locations was found to be lower than UNSCEAR's recommended level of 0.07 mSvy^-1 for soil in an outdoor environment. In the secondary study, gross α and gross β activities in soil and date palm pits samples were measured by a low background α/β counting system. Average values of gross α and gross β activities in soil and date palm pits samples were 5.761 ± 0.360 Bqkg^-1, 38.219 ± 8.619 Bqkg^-1 and 0.556 ± 0.142 Bqkg^-1, 24.266 ± 1.711 Bqkg^-1, respectively.

• Korean Journal of Microbiology
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• v.52 no.4
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• pp.500-502
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• 2016

Several bacterial species have been reported to be surviving after the ionizing radiation treatment due to the presence of sophisticated enzymes systems and some endospores producing bacterial strains can also resist, due to the presence of thick spore coat. In this study, we report the complete genome sequence of a bacterium Paenibacillus swuensis $DY6^T$, isolated from an irradiated soil sample. The genome comprised of 5,012,599 bp with the G+C content of 49.93%, the genome included 4,463 protein coding genes and 133 RNA genes.

• Nuclear Engineering and Technology
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• v.20 no.1
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• pp.65-70
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• 1988

A Shielding analysis of the shipping cask designed conceptually, of which shielding material are lead and resin, for containing 4 PWR spent fuel assemblies, has been made with the help of a computer code, ANISN. The shielding materials being used in the cask have been selected and arranged to minimize cask weight while maintaining an overall shielding effectiveness. Radiation source terms have been calculated by means of ORIGIN-2 code under the assumptions of 38,000 MWD/MTU burnup and 3-year cooling time. A calculation of gamma-ray and neutron dose rates on the cask surface and 1m from the surface has been done. It is revealed that the total dose rates under the normal transport and hypothetical accident conditions meet the standards specified.

• Journal of the Korean Society of Radiology
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• v.9 no.2
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• pp.73-77
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• 2015

In order to observe the detailed structure of the detector, it was CT scanned to reproduce the detailed structure of the crystal shapes and traverse layer using the Monte Carlo calculation applying the detector model. The uncertainty of measurement was lowered by adjusting the detector core by the edge effect at a higher energy (400 keV or higher) through the offset of peak efficiency of the gamma ray at low energy. It was confirmed that there was the appropriate matching with spatial dependency using the PENELOPE calculation. That was achieved by adjusting the parameters describing the crystal core and rounding of edge and crystal core.

• The Korean Journal of Nuclear Medicine
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• v.24 no.2
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• pp.307-316
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• 1990

Irradiation is widely used for the treatment of malignant diseases, and possibly cause the osteoporosis. The densitometry and bone scintigraphy are valuable when used to monitor the patients longitudinally to access the progression of osteoporosis and risk of osteoradionecrosis. To evaluate the osteoporosis after irradiation of Cobalt-60 gamma ray on the lumbar spines of New Zealand white rabbits, bone densitometry by dual photon absorptiometry and bone scintigraphy were performed weekly. The decrease of bone density began at the first week after irradiation, and were in the nadir at 4-6th week. The osteoblastic activity measured by bone scintigraphy decreased in the first week, and was in the nadir at 4-6th week. The severity of these changes were related to the radiation dose. In conclusion, the osteoporosis before the presentation of the osteoradionecrosis can be diagnosed early with the dual photon absorptionmetry and bone scintigraphy.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.10a
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• pp.150-152
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• 2005

환경친화적 기술로 알려진 방사선조사기술(RT: Radiation Technology)을 이용하여 돈피 유래 올리고펩타이드를 제조하고자 하였다. 생 박 돈피를 hammer mill과 chopper를 이용하여 조분쇄한 후 $-20^{\circ}C$ 아세톤으로 탈지하였고, ${\gamma}$-ray irradiator를 이용하여 0, 20, 40, 60, 100, 150, 200, 250, 300 kGy의 총 흡수량을 얻도록 탈지돈피에 방사선조사를 실시하였다. 방사선조사에 의한 탈지돈피의 pH 변화는 0${\sim}$100 kGy 조사선량에서는 미비했으나, 150 kGy 이상에서는 소폭 증가하였다. 탈지돈피의 단백질 함량 중 콜라겐 함량은 93% 이었으며 방사선조사된 돈피콜라겐을 효소처리하면 효소반응 시간이 길어질수록 약 24 kDa 범위에서 밴드가 확인되었고, 100 kGy 이상의 고선량에서는 효소반응 2시간 이후 10% polyacrylamide 전기영동 겔의 최 하단에 머무는 분자량의 펩타이드가 다량 관찰되었다. 용해도 변화는 20${\sim}$60 kGy의 선량에서는 효소반응 시간이 길어질수록(1시간${\sim}$4시간) 최대 65${\sim}$80%의 용해도 증가를 보였고, 반면에 100 kGy 이상에서는 효소반응 시간에 관계없이 80% 이상, 300 kGy에서는 90% 이상의 용해도를 보여주려다. 점도와 탁도는 100 kGy 이상의 고선량에서 짧은 효소반응 시간(1시간)에 급격히 감소하였다. 가수 분해물(300 kGy)을 gel permeation chromatography한 결과 분자량 9,000 Da의 주 피크가 검출되었다.

• Journal of The Korean Astronomical Society
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• v.50 no.4
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• pp.93-103
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• 2017

We explore the shock acceleration model for giant radio relics, in which relativistic electrons are accelerated via diffusive shock acceleration (DSA) by merger-driven shocks in the outskirts of galaxy clusters. In addition to DSA, turbulent acceleration by compressive MHD modes downstream of the shock are included as well as energy losses of postshock electrons due to Coulomb scattering, synchrotron emission, and inverse Compton scattering off the cosmic background radiation. Considering that only a small fraction of merging clusters host radio relics, we favor a reacceleration scenario in which radio relics are generated preferentially by shocks encountering the regions containing low-energy (${\gamma}_e{\leq}300$) cosmic ray electrons (CRe). We perform time-dependent DSA simulations of spherically expanding shocks with physical parameters relevant for the Sausage radio relic, and calculate the radio synchrotron emission from the accelerated CRe. We find that significant level of postshock turbulent acceleration is required in order to reproduce broad profiles of the observed radio flux densities of the Sausage relic. Moreover, the spectral curvature in the observed integrated radio spectrum can be explained, if the putative shock should have swept up and exited out of the preshock region of fossil CRe about 10 Myr ago.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.297-303
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• 1989

Attempts to isolate the naturally occurring ultra-violet resistant bacteria from environmental sources were made. The isolates, designated No.29, 100, and 107, among numbers of bacterial isolates revealed a remarkable resistance to UV ray, whose degree of resistance in dose/response kinetics was comparable to that of an endospore-former, Bacillus subtilis. In a range of 100-300 $Jm^{-2}$/min of UV irradiation, the isolates exhibited 500-1000 fold resistance compated with E. coli. The isolated appeared to possiss cell-bound pigment of organge or crimson-red. The isolate 29 is spherical in pairs or tetrads, whereas the isolates 100 and 107 are rod. All are Gram-gositive bacteria and seemed to be non-endospore-bearer. A number of biochemical studies pursued on the isolates suggested that they are quite different to each other. Electron microscopic examination and the physiological characters of the isolate 29 suggested that this UV resistant spherical bacterium might be one species of Deinococcus, probably Deinococus radiophilus. Since there is no documents on UV resistant, Gram-positive, non-sporeformer bacillus so far, the isolates 100 and 107 might be turned out as new kinds of UV resistant bacteria occurring in nature by further investigation.

• Korean Journal of Oriental Medicine
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• v.9 no.2
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• pp.107-119
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• 2003

In this study, Kami-honghwa-tang (KH-19) was designed and animal study was conducted to evaluate its efficacy on the reduction of the side effect of radiotherapy. Bone marrow toxicity is one of the major side effect of radiotherapy which cause the reduction of blood cells, and KH-19 was designed to protect and enforce blood. C57BL/6 mice were irradiated with 4 Gy of gamma ray, and divided into control group which was treated with water and KH-19 group which was treated with 1.5g/Kg of KH-19 up to 4 weeks. KH-19 group showed significantly increased white blood cells, lymphocytes and platelet count compared with control group (p<0.05). When bone marrows were examined, KH-19 group showed higher cell densities than control group (p=0.06). KH-19 may increase blood cell count after radiation by its protective effects on bone marrow.