• 한국방사선학회논문지
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• 제10권5호
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• pp.337-341
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• 2016

중성자에너지 영역 0.003 eV에서 10 eV에 대해 천연 Sm의 Sm(n,${\gamma}$) 반응에 대한 중성자 포획단면적을 측정하였다. 교토대학교 원자로실험소의 46-MeV 전자선형가속기에서 발생되는 전자의 광핵반응에 의한 중성자를 사용하였고 TOF 방법으로 측정하였다. 사용한 검출기는 12개의 BGO($Bi_4Ge_3O_{12}$) 섬광체로 구성되었고 이 검출장치로 Sm(n,${\gamma}$) 반응으로부터 나오는 즉발감마선을 측정하였다. 검출장치는 중성자 생성 위치로부터 $12.7{\pm}0.02m$ 위치에 설치되었으며 $^{10}B(n,{\alpha}{\gamma})^7Li$ 반응을 이용해 Sm 시료에 입사되는 중성자 선속을 구하였다. 또한 중성자 선속의 변화를 확인하기 위해 $BF_3$ 검출기로 모니터링 하였다. Sm(n,${\gamma}$) 반응단면적 측정결과는 BROND 2.2에 의한 평가결과와 J. C. Chou 및 V. N. Kononov 의 측정값과 비교하였다.

• 센서학회지
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• 제24권3호
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• pp.202-207
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• 2015

As a feasibility study on development of a gamma imaging probe, we developed a scintillating film-based gamma imaging detector that can obtain scintillation images with information of gamma-ray distribution. The scintillating film-based gamma imaging detector was composed of a sensing probe, an image intensifier, and a beam profiler. To detect and transmit scintillation image, the sensing probe was fabricated by coupling a scintillating film, a fiber-optic image conduit, and a fiber-optic taper, consecutively. First, the optical images of USAF 1951 resolution target were obtained and then, modulation transfer function values were calculated to test the image quality of the sensing probe. Second, we measured the scintillation images according to the activity of the 137Cs and the distance between the surface of 137Cs and the distal-end of sensing probe. Finally, the intensities of scintillating light as functions of the activity and the distance were evaluated from the region of interest in the scintillation image. From the results of this study, it is expected that a fiber-optic gamma imaging detector can be developed to detect gamma-rays emitted from radiopharmaceuticals during radioimmunoguided surgery.

• Journal of Radiation Protection and Research
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• 제47권4호
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• pp.214-225
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• 2022

Background: The conventional cerium-doped Gd₂Al₂Ga₃O₁₂ (GAGG(Ce)) scintillator-based gamma-ray imager has a bulky detector, which can lead to incorrect positioning of the gammaray source if the shielding against background radiation is not appropriately designed. In addition, portability is important in complex environments such as inside nuclear power plants, yet existing gamma-ray imager based on a tungsten mask tends to be weighty and therefore difficult to handle. Motivated by the need to develop a system that is not sensitive to background radiation and is portable, we changed the material of the scintillator and the coded aperture. Materials and Methods: The existing GAGG(Ce) was replaced with Bi₄Ge₃O₁₂ (BGO), a scintillator with high gamma-ray detection efficiency but low energy resolution, and replaced the tungsten (W) used in the existing coded aperture with lead (Pb). Each BGO scintillator is pixelated with 144 elements (12 × 12), and each pixel has an area of 4 mm × 4 mm and the scintillator thickness ranges from 5 to 20 mm (5, 10, and 20 mm). A coded aperture consisting of Pb with a thickness of 20 mm was applied to the BGO scintillators of all thicknesses. Results and Discussion: Spectroscopic characterization, imaging performance, and image quality evaluation revealed the 10 mm-thick BGO scintillators enabled the portable gamma-ray imager to deliver optimal performance. Although its performance is slightly inferior to that of existing GAGG(Ce)-based gamma-ray imager, the results confirmed that the manufacturing cost and the system's overall weight can be reduced. Conclusion: Despite the spectral characteristics, imaging system performance, and image quality is slightly lower than that of GAGG(Ce), the results show that BGO scintillators are preferable for gamma-ray imaging systems in terms of cost and ease of deployment, and the proposed design is well worth applying to systems intended for use in areas that do not require high precision.

• 한국식품과학회지
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• 제31권4호
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• pp.1050-1056
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• 1999

식품첨가제의 사용없이도 저장성과 향미특성이 우수한 저염 오징어젓갈을 개발하기 위한 방법으로 감마선 조사기술을 이용하였다. 식염농도를 각각 5%, 10%, 20%로 조절한 오징어젓에 감마선을 조사한 후 $15^{\circ}C$와 $25^{\circ}C$에서 발효시키면서 일반성분, 식염함량, 수분활성도, pH, 총균수 및 관능적 품질 변화를 조사하였다. 감마선 조사직후 또는 발효기간 중 일반성분과 식염함량 및 수분활성은 감마선 조사에 의해 영향을 받지 않았다. 오징어젓갈의 총균수와 pH는 식염농도와 감마선 조사선량 및 발효온도에 따라 영향을 받았으며, 10%의 식염 첨가와 10 kGy의 감마선 조사를 병용처리한 오징어젓을 $15^{\circ}C$에서 발효시킨 경우 비조사구에 비해 적절한 미생물의 생육 저해로 저장기간 연장 효과를 보였고, 30일까지 관능적 품질이 적합하게 유지되는 것으로 나타났다.

• 비파괴검사학회지
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• 제19권5호
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• pp.356-362
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• 1999

공업용 방사선 필름의 필름 농도가 대략 3.5 이하의 농도 구간에서 상대 노출에 대해 지수 함수적으로 증가한다고 가정하여, 필름특성곡선에 관한 일반식과 두께 변화에 대한 농도 변화 관계식을 새로이 제안하였다. 연속 X-선과 $Ir^{192}$에 의한 ${\gamma}$-선으로 탄소강의 계단시편에 대해 시험한 결과, 대략 $1.0{\sim}3.5$의 농도 범위에서 두께 변화에 대한 농도의 상용 대수변화가 기존의 관계식에 비해 보다 선형적인 경향을 나타내었으며 실제 계단 시편의 치수와 제안한 관계식에 의한 평가를 비교한 결과 본 연구에서 제안한 농도-두께 관계식에 의한 결과가 기존의 관계식에 의한 결과보다 정확하였다. 그리고 시험체의 두께가 증가함에 따라 beam hardening effect에 의해 유효선흡수계수가 달라지는 연속 X-선에 비해 상대적으로 에너지 스펙트럼이 단순한 ${\gamma}$-선이 두께 평가를 위한 더 적합한 방사선원임을 확인하였다. 본 연구에서 제안한 관계식은 국부적인 부식 손상의 깊이와 분포도를 평가할 수 있으므로 압력 용기 등의 산업 설비의 건전성 평가에 활용할 수 있다.

• 한국재료학회지
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• 제18권3호
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• pp.128-136
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• 2008

Evaluation of the solid surface properties by an analysis of the liquid penetration rate into powder beds is very important in applications of powder products. The penetration rate is related the surface property in powder beds. In order to analyze the surface property of powders, the contact angle values of several powders were obtained using the Washbun equation and the Wicking method. The surface free energy value ${\gamma}S$ was divided into a polar component ${\gamma}S^p$ and a dispersion component ${\gamma}S^d$. Inorganic powders such as calcite were used as test samples. The effects of the particle size and the type of experimental liquid on the penetration rate were measured. It was confirmed that the surface free energy of the grinding sample is smaller than that of the classification sample.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2328-2333
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• 2020

The filter technique was applied to noise images, as noise is the significant factor that cause poor image quality due to lower photon counting. The purpose of this study is to confirm that image quality can be improved using the median modified Wiener filter (MMWF) technique; this is achieved via a National Electrical Manufacturers Association International Electrotechnical Commission body phantom with four large spheres that are filled with the ^99mTc radioisotope when evaluating the image quality. Conventional filters such as Wiener, Gaussian, and median filters were designed, and signal to noise ratio, coefficient of variation, and contrast to noise ratio were used as the evaluation parameters. The improvement in the image quality was in the following order, from the least to the highest improvement, in all cases: Wiener filter, Gaussian filter, median filter, and the MMWF technique. The results show that the image quality was improved from 20.6 to 65.5%, 7.4-40.3%, and 12.7-44.7% for the SNR, COV, and CNR values, respectively, when using the MMWF technique, compared with the use of conventional filters. In conclusion, our results demonstrated that the MMWF technique is useful for reducing the noise distribution in gamma camera images.

• 정보처리학회논문지D
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• 제15D권2호
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• pp.207-212
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• 2008

본 논문은 소프트웨어 비용추정 모델의 적합성을 평가하고, 가장 적합한 모델을 제시하였다. 먼저, 해당 모델의 함수를 변수변환시켜 선형식으로 만든다. 다음으로 실제 개발 소프트웨어의 비용 데이터가 모델의 선형식에 얼마나 적합한지로 모델의 성능을 평가한다. 모델 성능평가에는 절대오차 대신 상대오차 개념인 MMRE를 적용하였다. 기존의 소프트웨어 비용추정 모델은 Weibull, Gamma와 Rayleigh 함수를 따르고 있다. 본 논문에서는 성장곡선의 일종인 Gompertz 곡선 모델을 제안하였다. 추가로 다른 성장곡선들도 적합성을 검증하였다. 모델 성능평가 결과 Gompertz 성장곡선이 소프트웨어 비용추정 모델로 가장 적합한 성능을 보였다.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4652-4659
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• 2022

Among the detector materials available at room temperature, thallium bromide (TlBr), which has a relatively high atomic number and density, is widely used for gamma camera imaging. This study aimed to verify the usefulness of TlBr through quantitative evaluation by modeling detectors of various compound types using Monte Carlo simulations. The Geant4 application for tomographic emission was used for simulation, and detectors based on cadmium zinc telluride and cadmium telluride materials were selected as a comparison group. A pixel-matched parallel-hole collimator with proven excellent performance was modeled, and phantoms used for quality control in nuclear medicine were used. The signal-to-noise ratio (SNR), contrast to noise ratio (CNR), sensitivity, and full width at half maximum (FWHM) were used for quantitative analysis to evaluate the image quality. The SNR, CNR, sensitivity, and FWHM for the TlBr detector material were approximately 1.05, 1.04, 1.41, and 1.02 times, respectively, higher than those of the other detector materials. The SNR, CNR and sensitivity increased with increasing detector thickness, but the spatial resolution in terms of FWHM decreased. Thus, we demonstrated the feasibility and possibility of using the TlBr detector material in comparison with commercial detector materials.

• 동아시아식생활학회지
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• 제15권1호
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• pp.106-111
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• 2005

The gamma irradiation effect of dried fernbraken was investigated on the physical and sensory qualities during and after soaking process. Dried fernbraken packaged in vacuum was irradiated up to 7 kGy with v-ray produced by 132 Cs at 0℃. Moisture content and rehydration rate of gamma-irradiated fernbraken after soaking increased significantly depending on the irradiation doses(p<0.05). Lightness(L), redness(a) and yellowness(b) values of Hunter color system increased significantly in the gamma-irradiated fernbraken after soaking, compared with control, while the hardness and chewiness by the texture analyser decreased significantly in irradiated ones. Sensory evaluation results showed that the mean scores of flavor, appearance, taste, texture and over-all acceptability in soaked fernbraken irradiated were not significantly different from those in control, except higher preference score of texture in irradiated ones. From these results, it might be concluded that the irradiation does not affect the physical and sensory qualities of dried fernbraken during and after soaking, especially in texture.