• Title/Summary/Keyword: 감마(광자)

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Ultra Fast Flash Observatory에서 감마선 폭발로부터 나온 광자들을 검출/처리하는 장치 구현

  • Im, Hui-Jin;Linder, E.V.;Smoot, G.F;Grossan, B.;Park, Il-Heung;Nam, Sin-U;Nam, Ji-U;Lee, Jik;Park, Jae-Hyeong;Lee, Chang-Hwan
    • Bulletin of the Korean Space Science Society
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    • 2009.10a
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    • pp.47.5-48
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    • 2009
  • 감마선폭발(Gamma Ray Burst) 사건에서 순식간에 방출되는 광자들을 측정할 뿐만 아니라, 가시광 영역부터 감마선 영역 내에서 다른 변광하는 현상들을 연구하기 위해, 마이크로-인공위성에 탑재될 실험으로 Ultra Fast Flash Observatory(UFFO)을 제안한다. 이 UFFO의 핵심 기술은 Micro-Electro-Mechanical System mirrors가 빠른 시간이내에 타겟쪽으로 회전하여 측정하는 것이다. 이것은 우주상에서 감마선폭발로부터 오는 자외선/가시광선을 가장 빨리 측정하는 망원경으로, 이 현상의 생성 매커니즘을 이해하는데 중요한 정보를 제공할 것이다. 넓은 시야각을 가진 망원경으로부터 짧은 시간동안 순식간에 변하는 사건들을 판독하는 트리거 시스템과 제한된 처리 시간내에 망원경에서 검출기로 전달된 상당량의 데이터를 처리하는 신호처리 장치의 구현에 대해서 발표할 것이다.

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The Detection of Irradiated Agricultural Commodities by Origins with Photostimulated Luminescence (PSL) Analysis (Photostimulated Luminescence (PSL) 분석에 의한 원산지별 농산물의 방사선 조사여부 검지)

  • 정재영;이은영;권중호
    • Food Science and Preservation
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    • v.8 no.3
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    • pp.291-295
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    • 2001
  • Photostimulated luminescence (PSL) analysis was applied to determine whether some agricultural commodities of Korean and Chinese origins have been irradiated or not. Cereals (brown rice and buckwheat) and legumes (soybean, peanut, fed bean and mung bean) were exposed to gamma irradiation at 0.5 ∼4 kGy The Korean garlic was irradiated at 0.05 ∼0.5 kGy. Cereals and mung bean were tool applicable to the PSL measurement, showing the intermediate values between the lower (700 photon counts, negative) and the upper threshold values (5,000, positive), however PSL values determined for soybean, peanut, red bean and garlic were suitable for being discriminated between nonirradiated and irradiated samples. There was no significant difference in PSL properties accgrding to the sample origins.

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감마선 폭발의 초기관측을 위한 Ultra-Fast Flash Observatory (UFFO) 프로젝트의 현황

  • Im, Hui-Jin;Park, Il-Heung;Nam, Ji-U;Nam, Gu-Hyeon;Yang, Jong-Man;Lee, Jik;Min, Gyeong-Uk;Kim, Seok-Hwan;Linder, E.V.;Smoot, G.F.;Grossan, B.
    • Bulletin of the Korean Space Science Society
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    • 2011.04a
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    • pp.20.3-20.3
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    • 2011
  • 감마선폭발 (Gamma Ray Burst) 사건에서 아직 관측이 안되고 있는 초기 방출 광자에 대한 연구를 위하여 Ultra Fast Flash Observatory (UFFO) 인공위성 프로젝트가 제안되었다. 이 탑재체의 주요 기기로써, 감마선 폭발의 위치를 측정하기 위하여 coded mask 기반의 X-ray 광시야각 망원경인 UFFO Burst Alert X-ray Trigger Telescope (UBAT)와 감마선 폭발의 자외선 및 가시광 초기 후광관측을 위한 Slewing Mirror Telescope(SMT)가 있다. UFFO 프로젝트는 한국이 주도하고 미국, 대만, 러시아, 덴마크, 스페인, 프랑스, 노르웨이, 폴란드가 참여하는 9개국 국제공동연구이며, 2011년 11월 UFFO pathfinder가 러시아 인공위성인 Lomonosov에 실려 발사될 예정이다. 차세대 UFFO-100는 2015년 발사 목표로 연구가 시작되고 있다. UFFO pathfinder의 현재 진행상황과 가능한 연구에 대하여 논의한다.

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Calculation of the Coupled Photon-Electron Slowing Down Energy Spectrum in a Homogeneous, Infinite Tissue Equivalent Material (무한평판(無限平板) 조직등가(組織等價) 물질(物質)에서 광자(光子)-전자결합(電子結合) 감속(減速) 에너지 스펙트럼의 계산(計算))

  • Chung, Chan-Young;Jae, Won-Mok;Lee, Soo-Yong;Ha, Chung-Woo
    • Journal of Radiation Protection and Research
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    • v.8 no.1
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    • pp.26-32
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    • 1983
  • A somewhat detailed energy spectra in terms of the track length resulting from coupled electron-photon slowing down are calculated throughout the ICRU standard tissue with uniformly distributed gamma sources of $^{60}Co\;and\;^{137}Cs$, respectively. The calculation was accomplished by utilizing the latest available cross-section data as input to a carefully optimized computer code. In this report, the calculational method is described in detail. Furthermore, results of calculations are given in graphical form. The results show that the energy spectrum defined in terms of differential track length has about same shape although the energies of gamma source are different. The discontinuity in the energy spectrum appears at the energy of $T=(1/T_0+2/m_0c^2)^{-1}$, because a primary photon can not be degrade to a point below this energy.

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Evaluation of Dosimetric Characteristics of Reproducibility, Linearity and Dose Dependence of Optically Stimulated Luminescence Dosimeters in Co-60 Gamma-rays (Co-60 감마선을 이용한 광자극발광선량계의 재현성, 선형성, 선량의존성에 대한 특성평가)

  • Han, Su Chul;Choi, Sang Hyoun;Park, Seungwoo;Kim, Chul Hang;Jung, Haijo;Kim, Mi-Sook;Yoo, Hyung Jun;Kim, Chan Hyeong;Ji, Young Hoon;Yi, Chul Young;Kim, Kum Bae
    • Progress in Medical Physics
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    • v.25 no.1
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    • pp.31-36
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    • 2014
  • We aimed to evaluate the dosimetric characteristics of reproducibility, linearity and dose dependence of optical stimulated luminance dosimeter (OSLD) in the Co-60 Gamma-rays and to analyze with a precedent study in field of the diagnostic radiography and radiotherapy. The reproducibility was 0.76% of the coefficient of variation, the homogeneity was within 1.5% of the coefficient of variation and OSLD had supra-linear response more than 3 Gy. So the correlation between dose and count was fitted by quadratic function. The count depletion by repeated reading was 0.04% per reading regardless of the irradiated dose. And the half time of decay curve according to the irradiated dose was 0.68 min. with 1 Gy, 1.04 min. with 5 Gy, and 1.10 min. with 10 Gy, respectively. In case of annealing for 30 min, the removal rate was 88% with 1 Gy, 90% with 5 Gy, and 92% with 10 Gy, respectively and 99% in case of annealing time for 4 hour. It is feasible to use OSLDs for dose evaluation in Co-60 Gamma-rays when considering the uncertainty on the procedure according to the irradiated dose.

Physicochemical Quality and Detection Properties of Irradiated Powdered-Soups (감마선 조사된 분말수프의 이화학적 품질과 조사여부 판별특성)

  • Kwak, Ji-Young;An, Yeoung-Eun;Jung, Bo-Yun;Kwon, Joong-Ho
    • Current Research on Agriculture and Life Sciences
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    • v.30 no.2
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    • pp.82-89
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    • 2012
  • Commercial powdered soups, such as potato soup(PS), corn soup(CS), and chicken-herb soup(CHS), were gamma-irradiated at 0, 1, 5 and 10 kGy and subjected to physicochemical evaluation and identification trials by analyzing photostimulated luminescence(PSL), electron spin resonance(ESR), and thermoluminescence(TL). The changes in moisture content and pH of soup samples were negligible upon irradiation. The Hunter's color determinations showed that lightness (L value) decreased and yellowness (b value) increased as the irradiation dose increased in PS sample. The viscosity of irradiated samples was reduced in the order of PS, CS and CHS. The analyses of PSL, ESR and TL were applicable to the identification of irradiated powdered-soups at more than 1 kGy by detecting PSL photon counts/60 sec(over 5000), radiation-induced multicomponents-ESR signal, and typical TL glow curve at $150-250^{\circ}C$.

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Comparison of Anti-Oxidative Activities of Gamma-Irradiated Aralia continentalis Extracts for Long-Term Storage of Oriental Medicine (한약재 장기 보존을 위해 감마선 조사한 독활(Aralia continentalis) 추출물의 항산화 효과 비교)

  • Park, Hye-Jin;Hong, Eun-Jin;Hong, Shin-Hyub;Cho, Young-Je
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.46 no.1
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    • pp.46-55
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    • 2017
  • In this study, extracts of gamma-irradiated Aralia continentalis for health and beauty food resources were examined on antioxidant activities and increasing extraction yield. In photostimulated luminescence analysis, non-irradiated (0 kGy) sample showed an intermediate result of 891.00 photon counts (PCs), whereas irradiated (5 and 10 kGy) samples showed positive results of 79,956.67 and 282,498.67 PCs, respectively. The thermoluminescence ratio of non-irradiated samples was 0.018, whereas the values of irradiated samples (5 and 10 kGy) were 0.395 and 0.464, respectively. Electron spin resonance (ESR) analysis as a physical technique for irradiation identification of Aralia continentalis showed a pair of peaks on a space of 6.0 mT in the symmetric ESR spectrums. For phenolics of gamma-irradiated Aralia continentalis, water extracts had the highest amounts of 7.61 mg/g at non-irradiated condition (0 kGy) while 50% ethanol extracts had the highest amounts of 6.86 mg/g at 10 kGy irradiation. 2,2-Diphenyl-1-picrylhydrazyl scavenging activity of water and 50% ethanol extracts from non-irradiated and irradiated Aralia continentalis were very high (94.99~100.00%). 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation inhibitory activity was over 95.00% at $200{\mu}g/mL$ phenolics. Antioxidant protection factor (PF) showed a very high level of activity (1.38~2.51 PF). Thiobarbituric acid reactive substance inhibitory activity was high (70% and 95%, respectively). Thus, treatment of gamma irradiation can be used as a method of storage for long-term preservation of Oriental medicine.

Relative Efficiency Determination of HPGe Detector (HPGe 검출기의 상대효율 결정)

  • 강정구;김승곤;김종일;이정옥;이춘호;최재우
    • Progress in Medical Physics
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    • v.4 no.2
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    • pp.27-36
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    • 1993
  • A relative efficiency of a HPGe detector as a function of the incident gamma ray energy in the range 120 keV to 1500 keV was measured using 21 gamma rays emitted by a $\^$152/Eu source. A semiempirical expression was then determined which can reproduce the measured values reasonably well. The two results are compared to a Monte Carlo simulation calculation.

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Combined X-ray CT/SPECT System with a Common CZT Detector (CZT검출기를 이용한 CT/SPECT 조합영상시스템)

  • 권수일
    • Progress in Medical Physics
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    • v.13 no.4
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    • pp.229-233
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    • 2002
  • We have tested a combined CT/SPECT system with a single CZT detector for x-ray and gamma-ray medical imaging. The size of detector is 10$\times$10$\times$5 ㎣, and the anodes are pixellated as a 4$\times$4 array with a pixel dimension of $1.5\times$1.5 $\textrm{mm}^2$. The cathode was coated with a continuous Au-plated. We have characterized the system performance by scanning a radiographic resolution phantom and the Hoffman Brain phantom. Pulse counting electronics with very short shaping time (50 ㎱) are used to satisfy high photon rates in x-ray imaging, and response linearity up to 3$\times$10$^{5}$ counts per second per detector element is achieved. Energy resolution of 10.4% and 5.3% FWHM at Tc-99m 140 keV peak are obtained for the 50 ㎱ and 2 $mutextrm{s}$ shaping times, respectively. The spatial resolutions of CT and SPECT are about 1mm and 9mm, respectively. Photopeak efficiency of detector systems are 41.0% for 50㎱ and 72.5% for 2 $mutextrm{s}$ shaping time.

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Calculation of Absorbed Dose for Immersion in Semi-Infinite Radioactive Cloud...(1) (반무한(半無限) 방사성운(放射性雲)에서의 흡수선량계산(吸收線量計算) - 1. 단일(單一)에너지 감마 방출체(放出體)에 대한 산난광자(散亂光子)스펙트럼의 계산(計算) -)

  • Lee, Soo-Yong
    • Journal of Radiation Protection and Research
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    • v.10 no.2
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    • pp.155-159
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    • 1985
  • In general, dose rates for a monoenergetic gamma emitter uniformly distributed in an infinite cloud have been calulated by using the monoenergetic point-isotorpic source kernel technique. The most serious limitation on use of the kernel technique is subjected to the fact that it estimates the dose only at the surface of body. As a result, an alternative method is presented in which estimates of dose rate for immersion in a radioactive cloud are resulted from the scattered photon spectra incident on the surface of body. The results are in excellent agreement with other's. Work is currently in progress to apply these results to immersion dose problems associated with absorbed dose distribution in the MIRD phatom.

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