• 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.

• 한국방사선학회논문지
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• 제11권3호
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• pp.101-108
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• 2017

DC/DC 컨버터는 임의의 직류전원을 부하가 요구하는 형태의 직류전원으로 변환시키는 효율이 높은 전력변환기이다. 고급형 DC/DC 컨버터는 MOSFET(산화물-반도체 전계 효과 트랜지스터)를 제어하기 위해 OP-Amp.(연산 증폭기)를 실장한 PWM-IC(펄스폭 변조 집적회로)를 사용한다. OP-Amp.는 증폭기 기능을 수행하는데 방사선 영향으로 전기적 특성이 변화하는데 본 논문에서는 코발트 60 (60Co) 저준위 감마발생기를 이용한 TID실험과 5종류의 중이온 입자를 이용하여 SEL 실험을 수행하는데 바이어스(bias) 전류가 순간적으로 과전류가 흘러 SEL이 발생된다. OP-Amp.의 TID 실험은 조사율은 5 rad/sec.로 전체 조사량을 30 krad 까지 수행하였으며, SEL 실험은 제어보드를 구현한 후 LET($MeV/mg/cm^2$)별 cross section($cm^2$)을 이용하여 성능평가를 하는데 있다.

• 대한방사선기술학회지:방사선기술과학
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• 제39권3호
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• pp.385-390
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• 2016

방사성옥소를 이용한 2인 치료격리병실은 환자간의 불필요한 피폭선량을 유발하게 된다. 이에 본 연구에서는 방사성 옥소를 섭취 후 배설 없이 모두 인체에 분포하였다는 가정 하에 방사성 옥소의 물리적 특성 및 생물역동학적 정보를 제외한 보수적인 관점으로 몬테카를로 모의 모사를 이용한 2인 치료격리병실의 안전성을 평가하고자 한다. 실험 결과 방사성옥소에서 방출되는 364 keV의 감마선은 공기층 약 30 cm 또는 납 차폐체 3 mm가 반가층으로 작용됨을 파악할 수 있었으며, 환자간 거리 및 납 차폐체의 두께를 이용하였을 때, 입원기간(48시간)동안 상대방 환자로부터 받게 되는 외부 피폭선량은 5 mSv 이하로 법적 격리 기준선량 보다 낮게 나타남으로써 2인 치료격리병실의 효율적인 관리가 가능한 것으로 분석되었다.

• 대한수의학회지
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• 제33권3호
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• pp.487-492
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• 1993

정상인 말초혈액임파구 및 C57BL/6마우스 비장임파구에 $^{60}Co{\gamma}-rays$를 in vitro상태에서 조사한 후 500개 또는 1000개의 cytokinesis-blocked(CB) lymphocytes의 미세핵(micronuclei)의 발생빈도를 측정하였다. 방사선조사량에 따라 미세핵의 발생빈도는 증가하였으며 linear-quadratic model로 측정한 결과 선량반응곡선의 식은 인체의 경우 $Y=(0.31{\pm}0.049)D+(0.0022{\pm}0.0002)D^2+13.19$($r^2=1.000$)이었으며, 마우스의 경우 $Y=(1.31{\pm}0.264)D+(0.0015{\pm}0.0006)+8.7$($r^2=0.988$)이었다(Y는 1000개의 CB cell 당 미세핵발생빈도, D는 cGy로 표시되는 조사선량). 인체 말초혈액임파구에 대한 마우스 비장임파구의 상대적 생물학적 효과(relative biological effectiveness)는 미세핵의 발생율이 세포당 0.05~0.8의 범위에서 $1.84{\pm}0.48$이었다. 미세핵분석법은 인체 및 동물의 방사선 피폭시 간편하고 빠른 생물학적 선량측정법으로 사용될 수 있을 것이다.

• 한국식품과학회지
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• 제9권3호
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• pp.205-210
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• 1977

시판(市販) 고추가루에서 13종의 곰팡이(Aspergillus amstelodami, Asp. clavatus, Asp. flavus, Asp. chevalieri, Asp. janus var. effusus, Asp. oryzae, Asp, oryzae var. brevis, Asp. repens, Asp. sydowi, Asp. thomii, Asp. tubingensis, Penicillium thomii, Scopulariopsis brevicaulis와 5종의 세균(Bacillus pumilus, Bac. subtilis, Micrococcus luteus, M. varians, Staphylococcus aureus)이 분리(分離), 동정(同定)되었다. 이들 미생물의 방사선 감수성(感受性)($D_{10}$ 값)을 보면 곰팡이는 $14{\sim}41\;krad$, 세균은 영양세포(營養細胞)가 $11{\sim}24\;krad$, 포자(胞子)가 $190{\sim}250\;krad$이었다. 햇 고추가루 중의 곰팡이 수는 1 g당 $2{\sim}3{\times}10^2$개, 세균은 $3{\sim}6{\times}10^7$개 이므로 200 krad의 방사선 조사(照射)로서 세균의 영양세포와 곰팡이 포자는 충분히 사멸(死滅)시킬 수 있다고 생각된다.

• 한국세라믹학회지
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• 제41권11호
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• pp.864-871
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• 2004

폐 염화알루미늄(AlCl$_3$) 수용액과 수산화나트륨(NaOH) 용액의 가수분해 반응에 의해 무정형의 수산화알루미늄 겔을 석출시키고, 이를 숙성하여 다공성 유사베마이트(pseudo-boehmite) 겔을 제조하였다 pH를 7.6～11.6 범위로 조절하고 반응온도를 60～10$0^{\circ}C$로 변화시켜 2～24시간 숙성시켰을 때, 겔 침전물의 결정변화, 적외선흡수스펙트럼의 변화, 비표면적 및 기공구조의 변화를 조사하여 최대 기공부피를 갖는 유사베마이트 겔의 제조조건을 확립하였다. pH 7.6～9.6 범위에서 석출된 겔 침전물로부터 250～357 $m^2$/g 정도의 비표면적과 0.4～0.74 cc/g의 기공부피 그리고 58～l14$\AA$의 평균기공크기를 갖는 다공성 유사베마이트가 제조되었으며, pH 10.6～11.6 범위에서 석출된 겔 침전물로부터는 기공이 거의 없는 베이어라이트(bayerite)가 제조되었다.