• Nuclear Engineering and Technology
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• 제56권2호
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• pp.715-727
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• 2024

During fast neutron imaging, besides the dark current noise and readout noise of the CCD camera, the main noise in fast neutron imaging comes from high-energy gamma rays generated by neutron nuclear reactions in and around the experimental setup. These high-energy gamma rays result in the presence of high-density gamma white spots (GWS) in the fast neutron image. Due to the microscopic quantum characteristics of the neutron beam itself and environmental scattering effects, fast neutron images typically exhibit a mixture of Gaussian noise. Existing denoising methods in neutron images are difficult to handle when dealing with a mixture of GWS and Gaussian noise. Herein we put forward a deep learning approach based on the Swin Transformer UNet (SUNet) model to remove high-density GWS-Gaussian mixture noise from fast neutron images. The improved denoising model utilizes a customized loss function for training, which combines perceptual loss and mean squared error loss to avoid grid-like artifacts caused by using a single perceptual loss. To address the high cost of acquiring real fast neutron images, this study introduces Monte Carlo method to simulate noise data with GWS characteristics by computing the interaction between gamma rays and sensors based on the principle of GWS generation. Ultimately, the experimental scenarios involving simulated neutron noise images and real fast neutron images demonstrate that the proposed method not only improves the quality and signal-to-noise ratio of fast neutron images but also preserves the details of the original images during denoising.

• Nuclear Engineering and Technology
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• 제4권1호
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• pp.39-45
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• 1972

중성자의 차폐를 고려할 경우 중성자의 차폐물질에 대한 감쇄와 마찬가지로 산란 효과가 중요함으로 이번 실험에서는 각종 방사선 차폐 물질인 납, 철, 콩크리트, 물, Paraffin, 및 borated paraffin등에 대해서 산란등가 선량을 Rem counter를 사용하여 측정하였다. 중성자선원은 Van de Graaff 가속기에서 얻은 0.5, 1, 2, 5, 및 18MeV의 중성자를 사용했으며 산란방향은 45$^{\circ}$, 90$^{\circ}$및 135$^{\circ}$의 3방향에 대해서 각 energy별로 측정하였다. 산란선은 산란체의 두께에 따라 증가하여 어느 이상의 두께에서는 포화상태가 되어 그 이상 증가하지 않았으며 납과 철이 제일 크고 수소함유량이 많은 물, paraffin등이 낮은 값임을 알았다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.153-153
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• 2003

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2001년도 춘계 공동학술발표회
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• pp.376-377
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• 2001

• 한국고분자학회지:고분자과학과기술
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• 제23권5호
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• pp.541-546
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• 2012

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.324-329
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• 2023

Different types of deterministic solution methods were used to solve neutron transport equations corresponding to half-space and slab albedo problems. In these types of solution methods, in addition to the error of the numerical solutions, the obtained results contain truncation and discretization errors. In the present work, a non-analog Monte Carlo method is provided to simulate the half-space and slab albedo problems with Inönü and Anlı-Güngör strongly anisotropic scattering functions. For each scattering function, the sampling method of the direction of the scattered neutrons is presented. The effects of different beams with different angular dependencies and the effects of different scattering parameters on the reflection probability are investigated using the developed Monte Carlo method. The validity of the Monte Carlo method is also confirmed through the comparison with the published data.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.633-646
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• 2020

Imaging and scattering techniques using thermal neutrons allow to analyze complex specimens in scientific and industrial researches. Owing to this advantage, there have been a considerable demand for neutron facilities in the industrial sector. Among neutron sources, an accelerator driven compact neutron source is the only one that can satisfy the various requirements-construction budget, facility size, and required neutron flux-of industrial applications. In this paper, a target, moderator, and reflector (TMR) system for low-energy proton-accelerator driven compact thermal neutron source was designed via Monte Carlo simulations. For 10-30 MeV proton beams, the optimal conditions of the beryllium target were determined by considering the neutron yield and the blistering of the target. For a non-borated polyethylene moderator, the neutronic properties were verified based on its thickness. For a reflector, three candidates-light water, beryllium, and graphite-were considered as reflector materials, and the optimal conditions were identified. The results verified that the neutronic intensity varied in the order beryllium > light water > graphite, the compacter size in the order light water < beryllium < graphite and the shorter emission time in the order graphite < light water < beryllium. The performance of the designed TMR system was compared with that of existing facilities and were laid between performance of existing facilities.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.51-51
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• 2002

나노기공물질은 특정 기반물질(matrix) 내부에 대략 나노미터크기의 기공을 함유하고 있는 물질이며 나노기공물질의 특성은 기반물질의 특성과 더불어 기공의 형태, 크기, 분포에 의해서 결정된다. 나노기공물질의 기공에 대한 정보를 측정하는 방법으로는 TEM, 흡착법, FE-SEM과 더불어 중성자 또는 X-ray 빔의 산란을 이용하는 소각중성자산란 (Small-Angle Neutron Scatering, SANS), 소각 X-ray 산란 (Small-Angle X-ray Scattering, SAXS), 중성자반사율측정 (Neutron Relfectimetry, NR), X-ray 반사율측정 (X-Ray Reflectometry, XRR) 등이 사용되고 있다. 본 발표는 대략 1 nm - 100 nm 영역의 bulk 구조와 층상구조를 측정할 수 있는 소각 중성자 산란과 중성자 반사율 측정기법을 이용한 나노기공 측정기술을 다룬다.

• 한국토양비료학회지
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• 제35권4호
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• pp.197-206
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• 2002

토양수분 이동에 대한 토양 특성과 경운의 영향을 구명하기 위하여 3년 동안 일리노이 중부지방의 몇 개 토양통이 다른 옥수수 포장에서 토양 수분함량을 조사하였다. 경작 기간중의 무경운과 경운된 포장에서 30 cm 간격으로 깊이 150 cm 까지 Neutron Scattering 기술에 의하여 수분함량을 측정하였다. 토양 경작층에서의 수분함량은 경운이나 강우에 의해 수분함량의 영향을 받은 반면 심토에서는 토성에 의해 영향을 받았다. 토양수분은 점토 함량이 상대적으로 낮은 Saybrook통이나 Catlin통에서 점토 함량이 높아 수분 보유능이 높은 Drummer통, Flanagan통, 및 Ipava통보다 빠르게 이동하였다. 이들 Drummer통, Flanagan통, Ipava통의 높은 유기물 함량은 수분 보유능을 증가시키는 또 다른 이유가 될 수 있다. 또한 옥수수 경작층에서의 수분함량은 경운 포장에서 무경운 포장보다 높았다.

• 한국재료학회지
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• 제14권5호
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• pp.348-352
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• 2004

The mechanical alloying (MA) effect in immiscible V-Cu system with positive heat of mixing was studied by not only the neutron and X-ray diffraction but also the analysis of DSC spectra. The total energy, ΔHt accumulated during MA for the mixture of $V_{50}$ $Cu_{50}$ / powders increased with milling time and approached the saturation value of 14 kJ/mol after 120 h of milling. It can be seen that the free energy difference between the amorphous phase and the pure V and Cu powders with an atomic ratio 5:5 is estimated to be 11 kJ/mol by Miedema et al. This is thermodynamically taken as one of the evidences for the amorphization. The structural changes of V-Cu MA powders were characterized by the X-ray diffraction and neutron diffraction. We take a full advantage of a negligibly small scattering length of the V atom in the neutron diffraction measurement. The neutron diffraction data definitely indicate that the amorphization proceeds gradually but incompletely even after 120 h of MA and bcc-Cu Bragg peaks appears after 60 h of MA.