• Radiation Oncology Journal
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• 제10권1호
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• pp.121-123
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• 1992

판톰 산란 인자($S_{p}$) 측정을 위한 새로운 방법을 소개한다. 측정용 전리함을 가릴 수 있는 블럭을 이용하여 $S_{p}$인자를 구할 수 있음을 이론적으로 증명하였으며, 이의 검증을 위해 $^{60}Co$을 이용하여 실험하였다. 이론값과 실험값과의 차이는 1%를 넘지않았다. 이 새로운 방법을 이용하면 고에너지 광자선측정에서 문제로 대두되고 있는 공기중 측정이 필요 없으며, 작은 블럭 차폐물만을 이용하여 $S_{p}$인자를 구할 수 있음을 확인하였다.

• Imaging Science in Dentistry
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• 제32권1호
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• pp.11-18
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• 2002

Purpose: To evaluate cultured human artificial skin as an experimental model for studying radiation effects in vitro. Materials and Methods: The skin was constructed by culturing keratinocytes over collagen lattice which made by culturing fibroblasts. Two groups were irradiated to gamma rays at single dose of 25 Gy with or without 3.5% of DMSO. Ultrastructures were investigated by electron microscopy after irradiation. The number of epidermal layers and expression of cytokeratin (CK) 14 & 10 were also seem by light microscopy. Results: At 2 days after irradiation in experimental group without DMSO, necrotic cells were rarely found in the spinosal layer and undercornified cells were visible in the homey layer. Similar findings were also found in experimental group with DMSO but in mild form. The number of epidermal layers in experimental group without DMSO were significantly fewer than other group. CK 14 expressed in all the layer excluding homey layer but CK 10 expressed over 3∼4 basal layers. Such patterns of CK expression were similar to all groups. It is suggested that structures of the keratinocytes and epidermal formation could be disturbed by irradiation in artificial skin and that DMSO can protect these damages. Conclusion : Therefore this work could be used as an organotypic experimental model in vitro using human cells for studying radiation effect in skin. Furthermore structural findings provided in this study could be used as useful basic data in further study using this model.

• 한국식품영양과학회지
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• 제14권1호
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• pp.57-60
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• 1985

녹두 종자 발아억제물질을 생산하는 균을 동정한 결과 Streptomyces luteogriseus로 판정 되었으며, 본 저해물질의 순도검정을 위해 silica gel thin layer chromatography를 행한 결과 BuOH-HOAc-formic acid-water(15 : 12 : 3 : 10)와 BuOH-HOAc-water(4 : 1 : 5)의 용매게에서 각 Rf 치는 0.85와 0.92 의 단일 spot가 확인되었다. 또한 본 저해물질의 주요 radical을 조사해 본 결과 phenol기, pyrimidine 기, amono 기, 환원당 및 auxin은 함유되지 않았으며 단지 UV조사에 의해 형광을 나타내었다. 본 저해물질의 UV spectrum은 ${\gamma}^{H20}_{max}=252$ 였으며, IR spectrum 에서는 $3300{\sim}3500,\;2900{\sim}3000,\;1600{\sim}1700$ 및 $1400cm^{(-1)}$의 peak가 인정되었다.

• Nuclear Engineering and Technology
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• 제5권2호
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• pp.103-114
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• 1973

본 실험은 방사선을 이용하여 Polyester 직포의 흡수성과 염색성 그리고 대전성을 증진시키기 위한 연구로서 실온하에서 함침법으로 Acrylic acid또는 4-vinylpyridine을 Polyester 직포에 접목시켰다. Polyester 직포를 25$^{\circ}$또는 7$0^{\circ}C$에서 Acrylic acid나 Acrylic acid와 4-vinylpyridine의 emulsion 용액에 함침시켰으며 함침된 Polyester 직포를 질소깨스 존재 하에서 Co-60의 l-rays로 조사시켰다. Acrylic acid가 접목된 Polyester 직포를 Sodium carbonate, Calcium acetate 또는 Potassium persulfate로 처리하였을 때 흡수율은 더욱 증가하였으며 직포 표면에 형성된 polyacrylic acid 는 0.1% NaoH 용액으로 대부분 추출되었다. 4-vinylpyridine과 Acrylic acid의 혼합용액을 함침용액으로 사용하였을 경우 4-VP/AA의 비율과 방사선 선량이 커짐에 따라 접목율은 점점 증가함을 보여주었다. 여러가지로 처리된 Polyester 직포 표면에 물방울을 떨어 뜨렸을 때의 Contact angle을 측정하여 보니 접목율이 증가함에 따라 대전성은 감소하였다. Acryli acid가 접목된 Polyester 섬유를 Salt로 처리하여 전자 현미경으로 관찰하여 본 결과 일련의 무정형 형태로 결합되어 있었다.

• 한국항공우주학회지
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• 제42권11호
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• pp.981-987
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• 2014

DC/DC 컨버터는 임의의 직류전원을 부하가 요구하는 형태의 직류전원으로 변환시키는 효율이 높은 전력변환기이다. DC/DC 컨버터는 MOSFET(산화물-반도체 전계 효과 트랜지스터), PWM-IC(펄스폭 변조 집적회로) 제어기, 인덕터, 콘덴서 등으로 구성되어있다. MOSFET는 스위치 기능을 수행하는데 코발트 60 ($^{60}Co$) 저준위 감마발생기를 이용한 TID 실험에서 방사선의 영향으로 문턱전압과 항복전압의 변화와 SEGR 실험에 적용된 5종류의 중이온 입자는 MOSFET의 게이트(gate)에 영향을 주어 게이트가 파괴된다. MOSFET의 TID 실험은 40 Krad 까지 수행하였으며, SEGR 실험은 제어보드를 구현한 후 LET(MeV/mg/$cm^2$)별 cross section($cm^2$)을 연구하는데 있다.

• 대한화학회지
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• 제16권1호
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• pp.40-45
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• 1972

An electron spin resonance study has been made on lysozyme in. frozen aqueous solutions irradiated with $_{60}Co$ r-rays in air at $77^{circ}K.$ Water resonances are dominant when the concentration and the temperature are both below 20% and $130^{circ}K$ respectively. More solute radicals are produced in the solution of higher concentration. Majority of the solute radicals results from direct hit of the radiation. The same types of radicals are induced at $77^{circ}K$ whether the substances are irradiated in the dry state or in frozen aqueous solution. Based on these results, it is assumed that the number of ESR centers produced by the secondary intermolecular radical reacions and stabilized in aqueous solutions may depend on the concentration of the solution, and the presence of water may facilitate the secondary radical reactions occuring in the solute molecules after heat treatment. Majority of the solute radicals above around $193^{circ}K$ are believed to react with oxygen to form peroxytype radicals. However, when the solution is subiected to heat-treatment at $265^{circ}K$ after irradiation at $195^{circ}K$ the peroxy-type resonance was not observed, suggestin that an appreciable amount of oxygen is condensed into the ice, at $77^{circ}K.$ in addition to the oxygen that has already been dissolved in solution and react with solute free radicals during the process of heat-treatment. When the solution contains $H_2O_2$, no water resonance but $HO_2$, type resonance was observed probably indicating that the radiation-induced OH radicals are trapped in $H_2O_2$ aggregates and react readily with $H_2O_2$ molecules to poroduce $HO_2$ type radicals even at $77^{circ}K.$.

• 한국응용곤충학회지
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• 제4권
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• pp.67-74
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• 1965

The work on the 'Studies of radiosensitivity' in Korea has been initiated since 1959 by the author at various institutions in home and foreign countries, and more than 20000 of plant materials in 73 varieties and 41 kinds are treated under varied conditions for the studies of radiosensitivity in plants. However, a study of the susceptibility to radiation in insect pests as well as their biological effects has not been previously reported in this country. During the year of 1964 and 1965, near 50000 of insects at the stages of adult, egg, larva and pupa in 14 different kinds are irradiated under acute X and gamma rays to investigate the behavior of growth and lethality after irradiation, and thrir general tolerances to radiations are compared by the kind of insects, stage of growth, radiation sources and exposured dosages. Through the experiments, it is shown that the lethality in most of insects are high as several kilo roentgens above and no significant effects on pupation. emergence, and oviposition in the treated generation at the dose of 3 Kr. below, but in the following generation , the rice stem borer for instance, no oviposition or decreased laying is observed from the dosages at 3 Kr. to 1 Kr., and the hatching was possible from 1.5 Kr. below of irradiated larvae although laying and hatching are seemed in normal. In general, the lethal dose $50\%$ of tested infect materials at the larval stage can he classified some what 60-80 Kr. for Pine caterpillar, Fall webworm, Camphor silk moth and their relatives, at 40-60 Kr. for Gypsy moth, Monley prominent and some relatives and at 20-30 Kr. for House fly, Rice weevil, Pine sawfly etc. Plant parasitic nematodes such as Hirschmannia and Paratylenchus shown very high resistance to radiation and the LD-50 is observed from 100 Kr. or above. A concept to evaluate the radiosensitivity in insects by taxological family line as a practical measure is not answerable yet, but it ran he solved within the near future through the continuing experiments.

• 한국방사선학회논문지
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• 제11권6호
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• pp.437-442
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• 2017

꿈의 암치료기라고 불리는 중입자 치료는 환자의 암세포에 입사하여 암세포만을 사멸하고 사라지는데 이때 중성자 및 감마선이 발생되어 치료실 내 영상장비, 그 밖의 전자장비에 영향을 미치게 된다. 중입자 치료시설을 구축하기 위해서는 약 2,000억 원 가량의 예산이 필요하며 구축기간도 5년 이상 소요된다. 따라서 구축 전 몬테카를로 시뮬레이션을 이용하여 치료실 내 선량 분포에 대해 관찰하여 적절한 대비를 하는 것이 중요하다. 본 연구에서는 몬테카를로 시뮬레이션 툴인 FLUKA를 이용하여 중입자 치료 시 치료실 내 선량분포에 대해 알아보았으며 1분 치료 시 치료실 내에는 약 0.1 mSv에서 2 pSv 정도의 영향이 있을 것으로 파악되었다.

• Journal of Radiation Protection and Research
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• 제9권2호
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• pp.67-75
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• 1984

As a part of studies on acute effects of high dose irradiation the present report was carried out to evaluate the changes of the leukocyte life span in the Newzealand white male rabbits by a single whole body exposure to gamma rays from $^{60}Co$ teleirradiation unit. The exposure was done in dose levels of 100, 300, 550 and 1,000 rad to each experimental group of 10 rabbits. The life span and apparent half survival time of leukocytes, and the elution rate of leukocytes in the circulating blood were measured by McMillan method using $^{51}Cr$. 1. As a critical indicator of radiation hazards of the Newzealand male rabbits, the LD 50/30 and LD 100/30 after whole body exposure was estimated as 550 and 1,000 rads respectively. 2. The life span of leukocyte in the circulation after irradiation was slightly shortened in the 100 rad irradiated group, as compared with the unirradiated control group, but markedly shortened in the 300, 550 and 1,000 rads irradiated group. 3. After irradiation, decrease of leukocyte half survival time in the circulation showed the same pattern as that of leukocytes life span. 4. As the irradiation doses increased, the elution rate of $^{51}Cr$ loss from $^{51}Cr$ tagged leukocytes in the circulation were markedly increased gradually. 5. The life span shortening of leukocytes in the circulation after irradiation seems to occure by two processes of senescence acceleration and early destruction.

• Asian Pacific Journal of Cancer Prevention
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• 제15권15호
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• pp.6161-6164
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• 2014

Background: We have reported the radiation could activate STAT3, which subsequently promotes the invasion of A549 cells. We here explored the dose- and time-response of STAT3 to radiation and the effect of radiation on upstream signaling molecules. Materials and Methods: A549 cells were irradiated with different doses of ${\gamma}$-rays. The expression of and nucleus translocation of p-STAT3 in A549 cells were detected by immunoblotting and immunofluorescence, respectively. The level of phosphorylated EGFR was also assessed by immunoblotting, and IL-6 expression was detected by real time PCR and ELISA. Results: Radiation promoted the phosphorylation of STAT3 at Y705 in a dose- and time-dependent manner and nuclear translocation. The level of phosphorylated EGFR in A549 cells increased after radiation. In additional, the mRNA and protein levels of IL-6 in A549 cells were also up regulated by radiation. Conclusions: STAT3 is activated by radiation in a dose-and time-dependent manner, probably due to radiation-induced activation of EGFR or secretion of IL-6 in A549 cells.