• Progress in Superconductivity
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• 제9권2호
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• pp.162-166
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• 2008

We are developing a sensitive gamma ray spectrometer based on superconducting transition edge sensors. The detector consists of a small piece of high purity Sn as an absorber and a Ti/Au bilayer as a temperature sensor. It is designed to measure the thermal signal caused by absorption of gamma rays. The mechanical support and the thermal contact between the absorber and the thermometer were made with Stycast epoxy. The bilayer was formed by e-beam evaporation and patterned by wet etching on top of a $SiN_X$ membrane. A sharp superconducting transition of the film was measured near 100 mK. When the film was biased to the edge of the transition, signals were observed due to single photon absorption emitted from an $^{241}Am$ source. The measured spectrum showed several characteristic peaks of the source including 59.5 keV gamma line. The full with at half maximum was about 900 eV for the 59.5 keV gamma line. The background was low enough to resolve low energy lines. Considerations to improve the energy resolution of the gamma ray spectrometer are also discussed.

• 한국물환경학회지
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• 제22권5호
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• pp.913-918
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• 2006

Both raw wastewater and effluent from a rubber products manufacturing factory were found to be toxic to Daphnia magna though the effluent satisfied current water quality standards. Thus, in order to reduce toxicity, advanced oxidation processes (AOPs) such as gamma-ray (${\gamma}-ray$) treatment and ozonation ($O_3$) were applied. A combined ${\gamma}-rays/O_3$ treatment at 20 kGy after coagulation significantly reduced toxicity of raw wastewater, changing 48-h toxic unit (TU) value from 201.21 to 23.92. However, toxicity of treated water was higher than that of effluent (TU = 12.15). This shows limitation of gamma-ray treatment to remove toxicity of raw wastewater. In case of effluent, the combined ${\gamma}-rays/O_3$ treatment at 20 kGy efficiently decomposed toxic compounds down to non toxic level. This work strongly supports the necessity of toxicity reduction evaluation as well as toxicity-based effluent management.

• Nuclear Engineering and Technology
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• 제2권4호
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• pp.273-278
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• 1970

국내에서 채광한 자연방사능광물의 분석의뢰를 계기로 이에 관심을 갖고 Uranium와Thorium 의 함유량을 원광으로부터 비파괴적이고 간단한 ${\gamma}$-선 분광법으로 측정 분석하여 보았다. Ge(Li) 측정기를 ${\gamma}$-선 분광에 이용한 결과는 재래식방법에 비하여 분석정도를 훨씬 높일 수 있었으며, 자연방사능측정법과 원자로중성자로 조사시킨 activation법으로 Uranium와 Thorium의 함유량을 분석하였던바 하나의 시료(인천에서 채광)에서는 약 0.5%의 Uranium, 또 다른 시료에서는 2%의 Th와 0.1%의 U이 포함되어 있음이 확인되었다. 우리가 처음 시도한 이 분석법은 경제적이고 간편.신속하게 분석할수 있어 핵연료물질조사에 널러 이용할 수 있음을 입증한다.

• Nuclear Engineering and Technology
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• 제7권3호
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• pp.223-226
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• 1975

${\gamma}$-선의 full-energy Peak에 대한 상대적 검출효율을 Pair-Point method에 의해서 결정하였다. 이때 사용된 방사선원은 ${\gamma}$-선의 상대적 방출율이 이미 잘 측정된 $^{56}$ Co 이 됐다. 이 방법을 통해서, ${\gamma}$-선 에너지 범위 800-3500keV에 걸쳐, 반응치적 43.8cc, 32.6cc 및 6cc의 Ge(Li) 검출기들의 검출효율을 보정하였다.

• Fibers and Polymers
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• 제5권3호
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• pp.225-229
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• 2004

The effect of UV and $^60{Co}$ gamma radiations on the physical and mechanical properties of nylon 6 mono-filaments with different draw ratios has been studied. Specimens were exposed to either up to 25 Mrad of gamma or up to 168 hrs of intense UV irradiation. The results show that nylon mono-filaments exposed to gamma rays, with much higher quantum energy than UV, undergo a larger extent of molecular chain scission. Higher irradiation dose also results in the production of insoluble, macroscopic three-dimensional cross-linked network structure. The amorphous regions with a lower density of cohesive energy (lower molecular orientation) show a higher extent of cross linking reaction whereas amorphous regions with a higher density of cohesive energy (higher orientation) show higher extent of chain scission reaction, irrespective of UV ray or gamma ray irradiation.

• 대한화학회지
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• 제12권2호
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• pp.55-60
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• 1968

芳香族誘道體 化合物의 鹽素化反應을 紫外線照射 및 ${\gamma}$-線照射下에서 行하였던 바 ethyl,${\alpha} ,{\beta} -dichloro-{\beta}$-phenyl propionate의 境遇 紫外線下에서는 主로 p-chloro 化合物이 生成되었다. 같은 反應을 ${\gamma}$-線 照射下에서 行한 結果 에스텔과 鹽素의 몰比가 1:2일 때에는 p-chloro 化合物이 主로 生成되었으나 몰比가 1:8인 境遇에는 側鎖鹽素化物이라고 判斷되는 多鹽素化合物이 生成되었다. 反應生成物을 確認하기 爲하여서 ethyl , ${\alpha} ,{\beta} -dichloro-{\beta}$-(p-chlorophenyl) propionate 및 ethyl${\alpha} ,{\beta} -dichloro-{\beta}$ -($o$-chlorophenyl) propionate 를 各各 ${\gamma}$-線 照射下에서 鹽素化시켜 보았더니 p-chloro誘道體에서는 側鎖鹽素化物을, o-chloro誘道體에서는 o,p-dichlorophenyl 化合物에 各各 該當하는 鹽素化物을 生成하였다. 化合物 確認에는 放射化 thin layer chromatography를 利用 하였으며 鹽素含量을 放射化分析法을 分析하였다. 反應結果를 鹽素化反應에 對한 芳香族의 置換基의 效果와 關聯시켜 論議하였으며 實驗方法을 記述하였다.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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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.

• 천문학회지
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• 제29권spc1호
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• pp.99-102
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• 1996

I discuss implications of gamma-ray emission from blazars based on electron acceleration by shock waves in a relativistic jet. The number spectrum of electrons turns out to be a broken power law; while at low energies the power law index has a universal value of 2, at high energies it steepens to an index of 3 because of strong radiative cooling. This spectrum can basically reproduce the observed spectral break between X-rays and gamma-rays. I show that energetics of relativistic jets can be well explained by this model. I estimate physical quantities of the relativistic jets by comparing the prediction with observations. The results show that the jets are particle dominated and are comprised of electron-positron pairs. A connection between gamma-ray emission and radiation drag is also discussed.

• 전기의세계
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• 제18권2호
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• pp.15-20
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• 1969

The main focus of this paper is on the study of the .gamma. ray irradiation effect upon the electrical properties of a B-kind insulator which is one of the inorganic insulators. The mica is so typical of the B kind insulators as to be selected for a sample. DC, AC, and Impulse voltage is applied to the variable .gamma. ray irradiated dose samples with the constant time duration and the time variable samples with the .gamma. ray irradiated dose. The dielectric breakdown voltage and dielectric constant are measured from the samples and we get the experimental data that the dielectric breakown voltage variations are relatively large, but the dielectric constants are almost constant. The above conclusion is useful for the selection and application of the inorganic insulators under the irradiation effects, and we expect that the conclusion can apply to not only B-kind insulators but also the inorganic insulators.

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2572-2580
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• 2020

Emerging gamma ray detection applications that utilize neutron-based interrogation result in the prompt emission of high-energy (>2 MeV) gamma-rays. Rapid imaging is enabled by scintillators that possess high density, high atomic number, and excellent energy resolution. In this paper, we evaluate the bright (50,000 photons/MeV) oxide scintillator, cerium-doped Gd₂Al₂Ga₃O₁₂ (GAGG(Ce)). A silicon photomultiplier (SiPM) array is coupled to a GAGG(Ce) scintillator array (12 × 12 pixels) and integrated into a coded-aperture based gamma-ray imaging system. A resistor-based symmetric charge division circuit was used reduce the multiplicity of the analog outputs from 144 to 4. The developed system exhibits 9.1%, 8.3%, and 8.0% FWHM energy resolutions at 511 keV, 662 keV, and 1173.2 keV, respectively. In addition, a pixel-identification resolution of 602 ㎛ FWHM was obtained from the GAGG(Ce) scintillator array.