• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.2230-2243
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• 2022

The tin tailing processing industry in Malaysia has operated with minimal regard and awareness for material management and working environment safety, impacting the environment and workers in aspects of radiation and heavy metal exposure. RIA was conducted where environmental samples were analyzed, revealing concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K between the range of 0.1-10.0, 0.0-25.7, and 0.1-5.8 Bq/g respectively, resulting in the AED exceeding UNCEAR recommended value and regulation limit enforced by AELB (1 mSv/y). Ra_eq calculated indicates that samples collected pose a significant threat to human health from gamma-ray exposure. Assessment of heavy metal content via pollution indices of soil and sediment showed significant contamination and enrichment from processing activities conducted. As and Fe were two of the highest metals exposed both via soil ingestion with an average of 4.6 × 10^-3 mg/kg-day and 1.4 × 10^-4 mg/kg-day, and dermal contact with an average of 5.6 × 10^-4 mg/kg-day and 6.0 × 10^-4. mg/kg-day respectively. Exposure via accidental ingestion of soil and sediment could potentially cause adverse non-carcinogenic and carcinogenic health effect towards workers in the industry. Correlation analysis indicates the presence of a relationship between the concentration of NORM and trace elements.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.207.2-207.2
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• 2012

The Ultra Fast Flash Observatory (UFFO) pathfinder consists of the UFFO Burst Alert X-ray Trigger telescope (UBAT) and the Slewing Mirror Telescope (SMT). They are controlled by the UFFO Data Acquisition system (UDAQ). The UBAT triggers Gamma-Ray Bursts(GRBs) and sends the position information to the SMT. The SMT slews the motorized mirror rapidly to the GRB position to take the UV/Optical data within a second after trigger. The UDAQ controls each instrument, communicates with the satellite, collects the data from UBAT and SMT, and transfers them to the satellite. Each instrument uses its own field programmable gates arrays (FPGA) for low power consumption and fast processing, and all functions are implemented in FPGAs without using microprocessors. The entire electronics system of the UFFO pathfinder including architecture, control, and data flow will be presented.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.5
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• pp.305-310
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• 2015

We propose a new concept for a depth of interaction (DOI) positron emission tomography (PET) detector based on dual-ended-scintillator (DES) readout for small animal imaging. The detector consists of lutetium yttrium orthosilicate (LYSO) arrays coupled with orthogonal wavelength-shifting (WLS) fibre placed on the top and bottom of the arrays. On every other line, crystals that are 2 mm shorter are arranged to create grooves. WLS fibre is inserted into these grooves. This paper describes the design and performance evaluation of this PET detector using Monte Carlo simulations. To investigate sensitivity by crystal size, five types of PET detectors were simulated. Because the proposed detector is composed of crystals with three different lengths, degradation in sensitivity across the field of view was also explored by simulation. In addition, the effect of DOI resolution on image quality was demonstrated. The simulation results proved that the devised PET detector with excellent DOI resolution is helpful for reducing the channels of sensors/electronics and minimizing gamma ray attenuation and scattering while maintaining good detector performance.

• Transactions of Materials Processing
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• v.29 no.1
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• pp.27-36
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• 2020

The Goss texture component of {110}<001> is well known as one of the best texture components to improve the magnetic properties of electrical steel sheets. The small amount of the Goss texture component is obtained at the surface of the steel sheet by shear deformation due to friction between the steel sheet and the roll during conventional symmetric rolling. This study aims to identify a method to obtain high intensity of the Goss texture component not only at the surface but in the whole layer of the steel sheet by shear deformation of asymmetric rolling. Low carbon steel sheets, which have different initial texture, were asymmetrically rolled by about 50%, 70%, and 80%. The pole figures of the top, center, and bottom layers of the initial and asymmetrically rolled low carbon steel sheets were measured by an X-ray diffractometer. Based on the measured pole figures of these samples, the intensities of the main texture components were analyzed for the initial and asymmetrically rolled low carbon steel sheets. As a result, the initial low carbon steel sheet with the γ-fiber component showed a higher intensity of the Goss texture component in the whole layer than the steel sheet with other texture components after asymmetric rolling.

• Journal of Dairy Science and Biotechnology
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• v.31 no.1
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• pp.67-73
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• 2013

Food allergy is defined as adverse reactions toward food mediated by aberrant immune mechanisms. Cow's milk allergy is one of the most common food allergies in childhood. This allergy is normally outgrown in the first year of life, however 15% of allergic children remain allergic. Cow's milk allergy seem to be associated with casein (${\alpha}_{s1}$-CN), ${\beta}$-lactoglobulin and whey protein. In addition to this, many other milk proteins are antigenic and capable of inducing immune responses. Various food processing affects the stability, structure and intermolecular interactions of cow milk proteins, as a result reduction the allergenic capacity. Heating, hydrolysis, chemical, proteolytic and other processes such as gamma-ray irradiation, high pressure, using probiotics treatments of milk to obtain hypoallergenic milk have been developed to reduce allergic reactions.

• Journal of Radiation Protection and Research
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• v.42 no.1
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• pp.33-41
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• 2017

Background: Phosphate rock and its by-product are widely used in various industries to produce phosphoric acid, gypsum, gypsum board, and fertilizer. Owing to its high level of natural radioactive nuclides (e.g., $^{238}U$ and $^{226}Ra$), the radiological safety of workers who work with phosphate rock should be systematically managed. In this study, $^{238}U$, $^{232}Th$, $^{226}Ra$, and $^{40}K$ levels were measured to analyze the transport characteristics of these radionuclides in the production cycle of phosphate rock. Materials and Methods: Energy dispersive X-ray fluorescence and gamma spectrometry were used to determine the activity of $^{238}U$, $^{232}Th$, $^{226}Ra$, and $^{40}K$. To evaluate the extent of secular disequilibrium, the analytical results were compared using statistical methods. Finally, the distribution of radioactivity across different stages of the phosphate rock production cycle was evaluated. Results and Discussion: The concentration ratios of $^{226}Ra$ and $^{238}U$ in phosphate rock were close to 1.0, while those found in gypsum and fertilizer were extremely different, reflecting disequilibrium after the chemical reaction process. The nuclide with the highest activity level in the production cycle of phosphate rock was $^{40}K$, and the median $^{40}K$ activity was $8.972Bq{\cdot}g^{-1}$ and $1.496Bq{\cdot}g^{-1}$, respectively. For the $^{238}U$ series, the activity of $^{238}U$ and $^{226}Ra$ was greatest in phosphate rock, and the distribution of activity values clearly showed the transport characteristics of the radionuclides, both for the byproducts of the decay sequences and for their final products. Conclusion: Although the activity of $^{40}K$ in k-related fertilizer was relatively high, it made a relatively low contribution to the total radiological effect. However, the activity levels of $^{226}Ra$ and $^{238}U$ in phosphate rock were found to be relatively high, near the upper end of the acceptable limits. Therefore, it is necessary to systematically manage the radiological safety of workers engaged in phosphate rock processing.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.807-810
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• 2014

로봇 시스템의 제어 및 이를 이용한 환경 인식에는 많은 전자 광학 소자들이 사용되고 있다. 로봇 제어회로에 사용되고 있는 Si CMOS 공정의 CPU, ASIC, FPGA 소자는 고 선량의 감마선에 취약하다. 환경정보 수집용으로 로봇에 탑재되는 CMOS/CCD 카메라의 관측영상에는 고선량 감마선으로 인한 speckle (백색잡음, white noise) 들이 나타나며, 이들이 카메라의 관측성능을 저하시킨다. 후쿠시마 원자력발전소 사고와 같이 원자력시설에서 제어불능의 심각한 사고가 발생되면 고선량 감마선이 방출된다. 이러한 고선량 감마선방출은 사람에 의한 사고수습을 불가능하게 하며, 사고 수습을 위해서는 로봇의 활용이 불가피하다. 그러나, 방출되는 고선량 감마선의 세기(선량율)가 지나치게 높을 경우, 로봇 전자회로가 장애를 일으키기 때문에 로봇의 적절한 임무수행이 가능한 감마선 세기에 대한 고려가 필요하다. 본 논문에서는 고선량 감마선 환경하에서의 로봇 탑재 CCD/CMOS 카메라의 관측 성능을 고려하여 100 Gy/h 를 감마선 선량율 제한조건으로 설정한다. 그리고, 재 가동 승인심사를 받기 위해 일본의 원전 운영자들이 제시한 PWR (가압경수로) 원전의 중대사고 대책 적합성 평가문서에 나타난 노심용융개시 시점의 원자로 격납건물내 감마선 선량율 추이 계산결과를 활용하여 로봇의 대응시간을 계산하였다. 문서 (PDF) 에 표현된 감마선 선량율 추이 그래프를 영상 판독하여, 격납건물내 감마선 선량율이 100 Gy/h 제한조건에 도달하는 시간을 계산하였다. 이를 로봇의 대응시간으로 설정한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.811-814
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• 2014

일본 후쿠시마 제일 원자력발전소의 대지진/쓰나미에 이은 원자로 건물 수소폭발 사고의 수습 과정에서 사용후 핵연료 저장조에 보관되어 있는 핵연료의 안전문제가 대두되었다. 사용후 핵연료의 잔열 성분을 냉각시키고, 그리고 사용후 핵연료가 방출하는 고선량 방사선을 차폐시키기 위해서 일정 깊이 이상의 수조에 사용후 핵연료를 저장한다. 사용후 핵연료 저장조에 냉각수 공급이 중단되면, 사용후 핵연료의 고유 잔열에 의해 수조의 물이 증발하여 수위가 감소하게 된다. 계속해서 냉각수 공급이 되지 않으면, 사용후 핵연료의 잔열은 증가하게 되고, 수조의 물은 비등하여 증발은 가속화 된다. 사용후 핵연료 저장조의 수위가 고갈되면 고선량의 감마선이 방출된다. 수조의 수위가 정상적일 경우 사용후 핵연료 저장조의 공기중 감마선 선량율은 0.15mSv/h 이다. 수조의 수위가 사용후 핵연료 상부 꼭대기를 기준으로 2m, 1m, 및 0m (핵연료 노출) 로 감소하게 되면, 사용후 핵연료 저장조의 공기중 감마선 선량율은 500mSv/h, 50Sv/h, 및 5kSv/h 로, 급격히 증가한다. 본 논문에서는 사용후 핵연료 저장조 감시카메라의 관측 성능을 평가하기 위해, 고성능 칼라 CCD 카메라에 대해서 1 kGy/h 의 고선량율로 감마선 조사실험을 수행하였다. 이에 대한 실험결과를 기술한다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.5
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• pp.588-593
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• 2006

This study was intended to observe possibility of which radiation technique can be used for oligopeptide production from pigskin collagen to reduce environmental pollution in processing and simplify the processing steps. Raw pigskin was ground using chopper, and then defatted in acetone cooled at $-20^{\circ}C$ freezer. Defatted dried pigskin was irradiated at 20, 40, 60, 100, 150, 200, 250, and 300 kGy using Co-60 gamma rays irradiator. With irradiation doses, the amount of soluble proteins increased, and the viscosity and turbidity of soluble proteins decreased, which could be clue of that irradiation degrade high molecular proteins directly. pH of soluble proteins from defatted pigskin increased in the sample above 150 kGy, and low molecular weight components (below 24 kDa) in SDS-PAGE increased. From gel permeation chromatography of the hydrolysates of pigskin irradiated at 300 kGy showed the major peak of 9,000, 8,200, 860, and 170 Da.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.791-797
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• 1993

The application of the pervaporation process in biotechnology is rapidly growing. A two stage pervaporation process can be applied to the downstream processing of ethanol fermentation. In this paper, the second stage process in which the water-ethanol composition was 50:50 wt.% was investigated in more detail by using Nylon 4 and its blended membranes containing poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). Nylon 4 membranes were tested for compositions at 25, 30, and $35^{\circ}C$. Nylon 4 membranes had a separation factor of 4.18 with a permeability of $0.69kg/m^2hr$ at water-ethanol composition of 50:50 wt.%, while nylon 4-PVA blended membranes crosslinked by 5 Mrad gamma-ray irradiation showed a higher separation factor of 10.56 with permeability $0.55kg/m^2hr$ at the same composition. Nylon 4 also showed a high separation factor 27.8 at the ethanol-water azeotropic composition among the homopolymer membranes.