• 한국안전학회지
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• 제32권2호
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• pp.34-37
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• 2017

In recent emerging industry, Display field becomes bigger and bigger, and also semiconductor technology becomes high density integration. In Flat Panel Display, there is an issue that electrostatic phenomenon results in fine dust adsorption as electrostatic capacity increases due to bigger size. Destruction of high integrated circuit and pattern deterioration occur in semiconductor and this causes the problem of weakening of thermal resistance. In order to solve this sort of electrostatic failure in this process, Soft X-ray ionizer is mainly used. Soft X-ray Ionizer does not only generate electrical noise and minute particle but also is efficient to remove electrostatic as it has a wide range of ionization. X-ray Generating efficiency has an effect on soft X-ray Ionizer affects neutralizing performance. There exist variable factors such as type of anode, thickness, tube voltage etc., and it takes a lot of time and financial resource to find optimal performance by manufacturing with actual X-ray tube source. MCNPX (Monte Carlo N-Particle Extended) is used for simulation to solve this kind of problem, and optimum efficiency of X-ray generation is anticipated. In this study, X-ray generation efficiency was measured according to target material thickness using MCNPX under the conditions that tube voltage is 5 keV, 10 keV, 15 keV and the target Material is Tungsten(W), Gold(Au), Silver(Ag). At the result, Gold(Au) shows optimum efficiency. In Tube voltage 5 keV, optimal target thickness is $0.05{\mu}m$ and Largest energy of Light flux appears $2.22{\times}10^8$ x-ray flux. In Tube voltage 10 keV, optimal target Thickness is $0.18{\mu}m$ and Largest energy of Light flux appears $1.97{\times}10^9$ x-ray flux. In Tube voltage 15 keV, optimal target Thickness is $0.29{\mu}m$ and Largest energy of Light flux appears $4.59{\times}10^9$ x-ray flux.

• 천문학논총
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• 제15권spc1호
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• pp.73-83
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• 2000

X-ray astronomy deals with measurements of the electromagnetic radiation in the energy range of $E\~0.1-100 keV (\lambda\~0.12-120{\AA})$. The wavelength of X-ray is comparable to the size of atoms, so that the photons in the X-ray range are usually produced and absorbed by the atomic processes. Since the launch of the first X-ray astronomy satellite 'Uhuru' in 1970, technological advances in a launch capability and a detection capability make X-ray astronomy one of the most rapidly evolving fields of astronomical research. Particularly, a spectral resolving power $E/{\Delta}E$ has been increased by an order of 2 - 3 (in the energy range of 0.1 - 10 keV) during the past 30years. In this paper, I briefly review a developing process of the resolving power and spectroscopic techniques. Then I describe important emission/absorption lines in X-ray astronomy, as well as diagnostics of gas property with line parameters.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.1062-1070
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• 2022

In the present communication, pure and stable α-Bismuth Oxide (Bi₂O₃) nanoparticles (NPs) were synthesized by low temperature solution combustion method using urea as a fuel and calcined at 500℃. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Visible absorption spectroscopy. The PXRD pattern confirms the formation of mono-clinic, stable and low temperature phase α-Bi₂O₃. The direct optical energy band gap was estimated by using Wood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range 0.081-1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shielding parameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accurate theory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present work opens new window to use this facile, economical, efficient, low temperature method to synthesize nanomaterials for X-ray/gamma ray shielding purpose.

• 대한방사선기술학회지:방사선기술과학
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• 제32권4호
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• pp.393-399
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• 2009

본 연구에서는 전리함을 이용하여 엑스선 촬영실 내에서 공간산란선량을 측정하고 산란선의 발생원과 조사 조건에 대한 산란율 의존성을 조사하였다. 아크릴 팬톰의 산란선 발생 인자를 조사하기 위해 관전압(40~140 kV)과 조사면($10{\times}10\;cm^2$, $20{\times}20\;cm^2$, $35{\times}35\;cm^2$)에 대한 산란율 변화를 측정하였다. 조사면이 $35{\times}35\;cm^2$일 때 측방산란율은 3.11~4.5%로 측정되었다. 촬영실 내에서 팬톰, 콜리메이터, 엑스선관, 벽면에서 발생하는 산란선량의 영향을 측정하였는데 전체 관전압에 대해 팬톰의 산란선 발생률은 95.4% 이상이었으며 콜리메이터, 엑스선관, 벽면의 산란선 발생률은 각각 2.6%, 1.3%, 0.7% 이하로 나타났다. 관전압 100 kV, 40 mAs 조사 조건에서 촬영실 내 팬톰으로부터 1 m 거리에서 측정한 공간선량은 최대 2 mR 정도로 나타나 조사조건의 최적화 등의 산란선 경감조치가 필요할 것으로 생각된다.

• Journal of Radiation Protection and Research
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• 제10권1호
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• pp.14-28
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• 1985

고순도 물질의 $K_{\alpha}$형광 X-선을 이용하여 100 keV 이하에서의 단색 Photon 선원을 개발하였다. 단색 Photon은 방사선 측정기기의 교정에 매우 유용한 것으로 얇은 금속박막의 Radiator에 제동복사선을 조사하여 얻을 수 있다. 본 실험에서는 $_{47}Ag,\;_{50}Sn,\;_{68}Er,\;_{70}Yb,\;_{82}Pb$, 등의 Radiator를 사용하여 20 keV 에서 80 keV의 범위에서 단색 Photon을 얻어내어 고순도 HpGe LEPS로 0.64-0.94에 이르는 단색도를 얻어내었고 600cc 얇은창이온전리함을 사용하여 8.3mR/h 에서 232. 5mR/h에 이르는 선량률을 얻어 내였다.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.287-290
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• 2001

The 9.17MeV gamma-rays from the $^{13}C(p,\;{\gamma})^{14}N,\;^{14}N({\gamma},\;{\gamma})^{14}N$ reactions were measured. The incident 9.17MeV gamma-ray was produced from the $^{13}C(p,\;{\gamma})^{14}N$ reaction at Ep=1.75MeV resonance. The 1.75MeV proton beam was accelerated using the 3MV SNU-AMS Tandetron and 1.7MV KIGAM Tandem accelerators. The enriched 13C target was $121{\mu}g/cm^2$ self-supporting foil, and we used liquid nitrogen as a resonant absorption target. We used a HP-Ge detector with 30% efficiency and less 2keV energy resolution. We developed new method to detect the scattered 9.17MeV gamma-ray from the nitrogen target by using the energy difference between the Doppler shifted gamma-ray from the $^{13}C(p,\;{\gamma})^{14}N$ reaction and the resonant absorbed and rescattered gamma-ray from the $^{14}N({\gamma},\;{\gamma})^{14}N$ reaction.

• 천문학회지
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• 제29권spc1호
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• pp.41-42
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• 1996

A possible cosmic X-ray background(XRB) radiation related to original antimatter is considered. If the universe is made of separating domains of antimatter and matter, the photons produced by the annihilation of electron-positron and proton-antiproton on the last scattering surface would reach us in the energy $\~$0.45 keV and $\~$60 keV respectively because of the redshift. The spectrums of X-ray radiation from annihilation are deduced and a possible observational figure is described also.

• 대한방사선기술학회지:방사선기술과학
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• 제41권2호
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• pp.129-134
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• 2018

The present study made a phantom for gamma ray of 140 keV radiated from $^{99m}Tc$, examined shielding effect of lead by thickness of the shielding material, and measured surface dose and depth dose by body depth. The OSL Nano Dot dosimeter was inserted at 0, 3, 15, 40, 90, and 180 mm depths of the phantom, and when there was no shield, 0.2 mm lead shield, 0.5 mm lead shield, The depth dose was measured. Experimental results show that the total cumulative dose of dosimeters with depth is highest at 366.24 uSv without shield and lowest at 94.12 uSv with 0.5 mm lead shield. The shielding effect of 0.2 mm lead shielding was about 30.18% and the shielding effect of 0.5 mm lead shielding was 74.30%, when the total sum of the accumulated doses of radiation dosimeter was 100%. The phantom depth and depth dose measurements showed the highest values at 0 mm depth for all three experiments and the dose decreases as the depth increases. This study proved that the thicker a shielding material, the highest its shielding effect is against gamma ray of 140 keV. However, it was known that shielding material can't completely shield a body from gamma ray; it reached deep part of a human body. Aside from the International Commission on Radiation Units and Measurements (ICRU) recommending depth dose by 10 mm in thickness, a plan is necessary for employees working in department of nuclear medicine where they deal with gamma ray, which is highly penetrable, to measure depth dose by body depth, which can help them manage exposed dose properly.

• 대한방사선기술학회지:방사선기술과학
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• 제30권3호
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• pp.245-250
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• 2007

진단용 방사선발생장치에서의 X선 에너지와 $^{99m}Tc$-MDP, $^{18}F$-FDG의 감마선 에너지 대한 apron 0.25, 0.5 mmPb에 대한 차폐율을 측정하였다. X선 에너지는 관전압 $40{\sim}120\;kVp$ 범위 내에서 부가여과판 0, 2 mmAl을 사용 한 경우에 실효에너지가 $26.2{\sim}45.6\;keV$로 측정되었으며, 이때 apron 0.5 mmPb은 0.25 mmPb보다 최대 선질에서 5.5% 정도 차폐율이 증가하였다. 또한 두 종류의 apron은 직접선과 공간선량률에 대하여 90% 이상의 높은 차폐율을 나타내었다. 그리고 $^{99m}Tc$-MDP의 140 keV에서 0.25, 0.5 mmPb apron을 사용할 경우 $30{\sim}53%$ 정도의 차폐효과가 있었으며, $^{18}F$-FDG의 511 keV의 높은 에너지에서는 $1.3{\sim}3.6%$로 apron의 차폐효과가 매우 적었다.

• Journal of Radiation Protection and Research
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• 제40권2호
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• pp.110-117
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• 2015

최근 방사선을 이용한 반도체 검사장비 산업의 증가로 이에 대한 기술 연구 수요 또한 증가하고 있다. 반도체 검사장비는 저에너지 엑스선으로 최저 40 keV에서 최고 120 keV의 에너지 영역을 사용하고 있지만, 국내에서는 저에너지 엑스선이 주는 방사선 손상 연구가 미흡한 상황이다. 따라서 본 연구는 저에너지 엑스선을 이용하여 반도체 소자의 한 종류인 BJT (bipolor junction transistor)가 받는 방사선 손상에 관한 것이다. BJT는 NXP반도체사의 BC817-25(NPN type)를 사용하였으며, 엑스선 발생장치를 사용하여 엑스선을 조사하였다. BJT의 방사선 손상 여부는 엑스선 조사 전과 후에 전류 이득을 10으로 고정하고, 콜렉터 전류에 따른 콜렉터-이미터 전압을 측정하여 변화 정도를 분석하여 확인하였다. 엑스선 발생장치의 관전압은 40 kVp, 60 kVp, 80 kVp, 100 kVp, 120 kVp 등 다섯 가지로, 조사 시간은 60초, 120초, 180초, 360초, 540초 등 다섯 가지로 변수를 두었다. 실험 결과 BJT에서 저에너지 엑스선 즉, 120 keV 이하의 엑스선을 조사하여도 방사선 손상이 발생하는 것을 확인하였고, 특히 80 kVp에서 가장 큰 방사선 손상이 발생되었다. 이는 ELDRS (enhanced low dose rate sensitivity) 현상이 80 kVp을 기준으로 발생되는 것으로 판단된다. 본 연구의 결과는 저에너지 엑스선을 이용한 반도체 검사장비의 효율적인 선량관리와 엑스선 여과기의 연구 및 개발에 기여할 것으로 기대한다.