• Journal of Radiation Protection and Research
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• v.11 no.1
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• pp.65-69
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• 1986

An asymmetry in dose profile of a $^{60}Co$ teletherapy unit was found by means of water-phantom measurement. The reason of that trouble was confirmed to be the abnormal 'ON' position of the source, which is resulted from the high friction between contiguous surfaces of the spring for driving the source to 'OFF' position. Lubrication in the spring improved the mobility a little, but was not a radical repair. The radical repair was to replace the old spring by new one. Periodic maintenance for source driving system and periodic measurement of field symmetry are required for prevention of abnormal 'ON' position of $^{60}Co$ source.

• Journal of radiological science and technology
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• v.13 no.2
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• pp.51-51
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• 1990

This study was undertaken to observe the effects of $^{60}Co\;{\gamma}-irradiation$ on the cell of spermatogenic epithelium in the testis of the chicken. 16-week-old chicken were provided as an experimental group and compared with control group. The experimental group was divided into a single irradiation (800, 1000, 1200 rads) and into three partial irradiation group (800/3, 1000/3, 1200/3 rads). The morphological changes of epithelial cell of the testis were observed by means of hematoxyline and eosin stain. Microstructure of spermatocyte and sperm was observed by means of semithin section of electron microscopic specimen. The results obstained are summerized as follows. 1. Spermatogonia and sertoli cells were found to be isolated from the basal membrane of seminiferous tubules as dose of $^{60}Co\;{\gamma}-irradiation$ was increased. 2. Spermatocytes of pachytene stage were seperated from the cytotplasmic process of sertoil cell in case of 1000 rads of $^{60}Co\;{\gamma}-irradiation$. 3. Normal arrangement of the cell of spermatogenic epithelium was found in control group and only the partial irradiation group of 800 rads. Vaculation in the seminiferous was pronounced in case of a single irradiation group of 800 rads, but the irradiation group of 1000 rads and 1200 rads were found to be damaged severely in both a single and a partial dose.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.195-198
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• 1990

In order to investigate the radiation effects induced to electrical properties of Biaxially-Oriented Polypropylen film, several observations were carried out to the sample irradiated to various dose by $Co^{60}-{\gamma}$ ray, on the characteristics of TSC spectra measuered as a function of electric field applied to a sample of 15[ ${\mu}m$] thick. The TSC spectra observed in the temperature range of $153{\sim}403[K]$ with the electric field of intensity $10{\sim}60$ [MV/m], have shown two of the distinguished peak such as ${\beta}$, ${\alpha}$, each of which appeared at $-5{\sim}20$ [ $^{\circ}C$] and 90 [ $^{\circ}C$] respectively. As the conclusions, obtained from the studies, the origin of ${\alpha}$ peak in TSC seems to be attributed by thermal excitation of ions trapped with $0.4{\sim}0.8[eV]$ deep, at the defects formed by $Co^{60}-{\gamma}$ irradiation in a crystaline region. The origin of ${\beta}$ peak was regarded as the depolarization process of "OH" or "CO" dipole with the activation energy of $0.4{\sim}0.6[eV]$ in an amorphous region.

• Electrical & Electronic Materials
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• v.4 no.2
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• pp.132-142
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• 1991

본 연구에서는 유기절연재료의 재방사선 재료개발을 위한다는 측면에서 두께 15[.mu.m]의 이축 연신 폴리프로필렌 필름을 시료로 선정하여 Co$^{60}$-.gamma.으로 조사시켜 온도 25-55[.deg.C], 전계 10-250[MV/m]사이에서 방사선 조사량 변화에 따른 전기전도현상을 연구하였다. 조사된 시료의 전기전도는 온도에 크게 의존하여 전계의 증가와 더불어 각기 다른 전도기구 특성을 갖는 4개의 영역으로 구분되었는데 각 영역별로 조사선량 변화에 따른 하전입자들의 거동상황을 규명하고 기초적인 제 물성정수를 결정하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.113-117
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• 1996

원자력시설 및 동위원소 이용기관에서의 인체오염사고에 대비하여, 피부제염기준을 조사하였으며, 피부제염제의 개발을 위하여 실험용 쥐를 대상으로 Co-60 및 Cs-137에 대해 비눗물, EDTA 및 KAERI-CON의 제염효과를 비교하였으며, 가장 효율적인 제염방법을 제시하였다. 각 제염제의 제염실험결과 Co-60 보다 Cs-137에 대한 제염이 더 잘 이루어졌으며, 제염횟수의 증가에 따라 방사능잔류율도 급격히 낮아졌다. KAERI-CON은 Co-60의 경우 38-55%, Cs-137의 경우에는 44-50%까지 제염효율을 보임으로서 타 제염제보다 효과적임을 확인하였다.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.60.2-60.2
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• 2008

• Journal of Hydrogen and New Energy
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• v.27 no.5
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• pp.554-561
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• 2016

Depending on the Bio-gas sources, main component gases of $CH_4$ and $CO_2$ are shown to be variously present in amounts. For the anaerobic digester, The concentration of $CH_4$ and $CO_2$ in the gases are 60~70 and 30~35 vol%. For the landfill gas, $CH_4$ and $CO_2$ are 40~60 and 40~60 vol%. For the food wastes, $CH_4$ and $CO_2$ are 60~80 and 20~40 vol%, respectively. In this study, maximum conversion rates of $CO_2$ were obtained from the variety of concentrations of $CH_4$ and $CO_2$ by the catalysts of reforming reactions. Moreover, in order to get maximum producing amount of synthetic gas, experimental studies were performed to optimize the reaction variables. On the basis of $CH_4$, 243 ml, R [$CH_4/(O2+CO_2)$] value were varied from 0.8 to 1.35, in the study of $CH_4$ and $CO_2$ reforming reactions. It was shown that the optimal results were obtained for 1.35 of R value. And also, at $850^{\circ}C$ and 1 atm, the production rate of synthetic gas was 90% and the conversion rates of $CH_4$ and $CO_2$ were higher than 99% and 90%, respectively.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2065-2069
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• 2014

The DAC-7512E is a 12-bit digital to analog converter that is low power and a single package with internal buffers. The DAC-7512E takes up minimal PCB area for applications of space power electronics design. The spacecraft mass is a crucial point considering spacecraft launch into space. Therefore, we have performed a TID test for the DAC-7512E 12-bit serial input digital to analog converter to reduce the spacecraft mass by using a low-level Gamma-ray irradiator with $Co^{60}$ gamma-ray sources. The irradiation with $Co^{60}$ gamma-rays was carried out at doses from 0 krad to 100 krad to check the error status of the device in terms of current, voltage and bit error status during conversion. The DAC-7512E 12-bit serial digital to analog converter should work properly from 0 krad to 30 krad without any error.

• Journal of Radiation Protection and Research
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• v.16 no.2
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• pp.7-16
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• 1991

Measurement of Co-60 gamma rays has been made for establishment of exposure standard and analyze it's overall uncertainties. Exposure rate determined by the charge mode method using vibrating reed amplifier with cylinderical type cavity chamber. The values of a variety of physical constants and the correction factors are evaluated. The resulting exposure rate is 690.81 R/h at the distance of 1m from the source and the related uncertainties is ${\pm}0.8%$

• Nuclear Engineering and Technology
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• v.14 no.2
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• pp.64-69
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• 1982

Directional correlation measurements for the Co-60 and Cs-134 cascade gamma-rays have been performed in the angular range from 90$^{\circ}$ to 180$^{\circ}$ by use of the fast coincidence scintillation spectrometer incorporated with a gamma-ray polarimeter based on the Compton scattering effect to determine the polarization correlations. The experimental method together with the theoretical background is described, and the results are shown graphically to represent the consistency of the measurement with approximate theoretical estimates.