• 한국방사선학회논문지
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• 제13권1호
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• pp.45-53
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• 2019

본 연구는 의료용 선형가속기 시설을 차폐하는 콘크리트에 대한 중성자 방사화 연구로써, 일반 콘크리트와 저 방사화 콘크리트를 비교 분석하였다. 실험 방법은 MCNPX (Ver. 2.5.0)와 FISPACT-2010를 사용하여 모의실험을 진행하여, 광자선과 중성자선에 대한 차폐능을 산정하고 중성자 방사화 평가를 진행하였다. 그 결과 차폐능은 일반 콘크리트에서 20~50 cm 효율적이였으며, 방사화 평가의 경우 저 방사화 콘크리트에서 방사능이 낮게 계산되었으나, 모두 자체처분허용 농도를 초과하지 않는 수준으로 산정되었다. 이를 종합적으로 분석한 결과 일반 콘크리트를 사용하는 것이 효율적인 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제56권8호
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• pp.3236-3241
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• 2024

Ion cyclotron resonance heating (ICRH) is an important auxiliary heating method applied to the China Fusion Engineering Test Reactor, which can effectively heat the ions and electrons in plasma. Owing to the harsh nuclear environment, neutronic analyses are required to verify tritium self-sufficiency and neutron-shielding requirements. In this study, a neutronics analysis of the ICRH antenna was conducted using the COre and System integrated engine for Reactor Monte Carlo (cosRMC) code to estimate the neutron flux, radiation damage, nuclear heating, gas generation rate of key components, and tritium breeding ratio (TBR), providing data support for the subsequent optimization of the shielding design. In addition, the neutron flux of the coils around the antenna was calculated to prevent the entry of neutrons that damage the magnetic field coils through the gaps between the port plugs and antenna, and the shielding effects of the port-plug antenna on the surrounding components were analyzed. Finally, the results obtained using the cosRMC and MCNP codes were compared, which and presented good agreement, thus verifying the reliability of the neutronic analysis using the cosRMC code.

• 한국방사선학회논문지
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• 제12권7호
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• pp.895-908
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• 2018

의료방사선의 관리에서 가장 중요한 사항은 진료의 적정성을 확보하면서 방사선위해를 최소화하는 것이다. 국제원자력기구는 진단방사선 분야의 선량 감소 방법에 대한 지침서를 만들어 환자피폭선량을 측정하여 각 국가에 사용하도록 권고하고 있다. 또한 국내에서도 우리나라의 실정에 맞게 각 촬영마다 환자 피폭 선량값을 연구하여 진단참고준위를 제시하였다.환자가 질병 때문에 방사선 진료를 받는 것은 방사선 때문에 일어날 수 있는 위해보다 그것으로 얻어지는 이익이 크기 때문이다. 병실 이동검사와 같이 자신의 질병과 무관하게 방사선에 노출되는 환자 및 보호자들의 피폭을 줄이기 위해서는 환자, 방사선사, 의사 및 의료기관의 노력이 가장 중요하다.이에 본 연구에서는 개선방안의 일환으로 MG로 병실의 이동 검사에 대한 문제점을 제시하고 이 문제점을 근거로 하여 산란선으로 예상되는 공간선량률을 분석하였다. MG에 자체 개발한 방어벽을 설치하여 방어벽 설치 전후의 공간선량률을 측정하여 그 감소율을 분석하였다. 최종적으로 이 자료들을 종합하여 MG에 방어벽을 부착하여 방사선사의 병실이동에 대한 부담감의 최소화, 병실 이동검사로 인한 방사선사, 환자 및 보호자를 방사선 노출로부터 보호하고, 검사로 인한 주위 환자 및 보호자의 불편을 최소화하는데 의의가 있다. 이와 같은 개선안에 대해 보다 효율적인 시행을 위하여 MG에 대한 새로운 법 제도가 마련되면, 향후 예상되는 비용, 인력, 고객만족도 및 더욱 더 안정적인 피폭감소방안이 정착될 것이라 사료된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.79-83
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• 2008

With excellent mechanical properties and durability of concrete and construction materials so far because, as has been the most widely used. However, existing in the electrical conductivity of the concrete material is given the characteristics of the concrete can not expand a lot of applications. For example, the cathode material of a parameter, ground resistance materials, electromagnetic shielding materials, sense of self-diagnostic materials, and anti-static materials are available. Currently, research on the electromagnetic shielding and absorbing mortar is incomplete. And Japan, the United States is part of the research in research institutions. Therefore, this research rate in the mouth in a different mix of conductive graphite particle the physical properties of cement mortar about the basic performance characteristics of the robbery was to figure out.

• Nuclear Engineering and Technology
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• 제45권6호
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• pp.753-758
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• 2013

A new method of calculating sensitivity coefficients of core characteristics relative to infinite-dilution cross sections has been developed. Conventional sensitivity coefficients are evaluated for the changes of effective cross sections which are dependent on individual models of core and cell. Therefore a correction has been derived to the conventional sensitivity coefficients based on the perturbation theory. The accuracy of the present method has been verified by comparing numerical results of sensitivity coefficients with a reference Monte-Carlo method.

• 한국정보통신학회논문지
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• 제24권9호
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• pp.1132-1137
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• 2020

유방 X선 촬영 장치를 이용한 유방 촬영을 실시할 때 발생되는 불필요한 피폭 선량을 경감시키기 위해 비스무스로 제작한 차폐체를 촬영 부위의 반대 측 유방에 적용했을 때 차폐율 분석을 실시하였다. 오른쪽, 왼쪽을 압박하였을 때 CC와 MLO 검사 시 압박되지 않는 유방의 산란 선량을 알아보기 위하여 비스무스를 차폐하지 않았을 때(Not used : NU그룹)와 차폐했을 때(Used : U그룹)로 구분하여 실험을 진행하였다. NU 그룹의 평균선량은 9.568μSv이었고, U그룹의 평균 선량은 1.038μSv이었다. 비스무스 차폐체 사용 전후의 평균 측정 선량은 89.15% 감소되었다. 유방 촬영용 비스무스 차폐체를 사용하면 산란 방사선을 차폐하여 방사선에 의한 노출을 최소한으로 유지할 수 있다.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.387-392
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• 2018

Various technical approaches and concepts have been proposed to develop conductive super-hydrophobic (SH) surfaces. However, most of these approaches are not usable in practical applications because of insufficient adhesion and cost issues. Additionally, durability and uniformity issues are still in need of improvement. The goal of this research is to produce a large-area conductive SH surface with improved adhesion performance and uniformity. To this end, carbon nanotubes (CNT) with a high aspect ratio and elastomeric polymer were utilized as a conductive filler and matrix, respectively, to form a coating layer. Additionally, nanoscale silica particles were utilized for stable implementation of the conductive SH surface. To improve the adhesion properties between the SH coating layer and substrate, pretreatment of the substrate was conducted by utilizing both wet and dry etching processes to create specific organic functional groups on the substrate. Following pretreatment of the surface, a zirco-aluminate coupling agent was utilized to enhance adhesion properties between the substrate and the SH coating layer. Raman spectroscopy revealed that adhesion was greatly improved by the formation of a chemical bond between the substrate and the SH coating layer at an optimal coupling agent concentration. The developed conductive SH coating attained a high electromagnetic interference (EMI) shielding effectiveness, which is advantageous in self-cleaning EMI shielding applications.

• Nuclear Engineering and Technology
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• 제47권7호
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• pp.791-803
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• 2015

The effective cross sections (XSs) in the direct whole core calculation code nTRACER are evaluated by the equivalence theory-based resonance-integral-table method using the WIMS-based library as an alternative to the subgroup method. The background XSs, as well as the Dancoff correction factors, were evaluated by the enhanced neutron-current method. A method, with pointwise microscopic XSs on a union-lethargy grid, was used for the generation of resonance-interference factors (RIFs) for mixed resonant absorbers. This method was modified by the intermediate-resonance approximation by replacing the potential XSs for the non-absorbing moderator nuclides with the background XSs and neglecting the resonance-elastic scattering. The resonance-escape probability was implemented to incorporate the energy self-shielding effect in the spectrum. The XSs were improved using the proposed method as compared to the narrow resonance infinite massbased method. The RIFs were improved by 1% in $^{235}U$, 7% in $^{239}Pu$, and >2% in $^{240}Pu$. To account for thermal feedback, a new feature was incorporated with the interpolation of pre-generated RIFs at the multigroup level and the results compared with the conventional resonance-interference model. This method provided adequate results in terms of XSs and k-eff. The results were verified first by the comparison of RIFs with the exact RIFs, and then comparing the XSs with the McCARD calculations for the homogeneous configurations, with burned fuel containing a mixture of resonant nuclides at different burnups and temperatures. The RIFs and XSs for the mixture showed good agreement, which verified the accuracy of the RIF evaluation using the proposed method. The method was then verified by comparing the XSs for the virtual environment for reactor applicationbenchmark pin-cell problem, as well as the heterogeneous pin cell containing burned fuel with McCARD. The method works well for homogeneous, as well as heterogeneous configurations.

• Nuclear Engineering and Technology
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• 제51권1호
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• pp.176-189
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• 2019

This paper presents a feasibility study for producing the medical isotope $^{99m}Tc$ using the hazardous and currently wasted radioisotope $^{99}Tc$. This can be achieved with the nuclear resonance fluorescence (NRF) phenomenon, which has recently been made applicable due to high-intensity laser Compton scattering (LCS) photons. In this work, 21 NRF energy states of $^{99}Tc$ have been identified as potential contributors to the photo-production of $^{99m}Tc$ and their NRF cross-sections are evaluated by using the single particle estimate model and the ENSDF data library. The evaluated cross sections are scaled using known measurement data for improved accuracy. The maximum LCS photon energy is adjusted in a way to cover all the significant excited states that may contribute to $^{99m}Tc$ generation. An energy recovery LINAC system is considered as the LCS photon source and the LCS gamma spectrum is optimized by adjusting the electron energy to maximize $^{99m}Tc$ photo-production. The NRF reaction rate for $^{99m}Tc$ is first optimized without considering the photon attenuations such as photo-atomic interactions and self-shielding due to the NRF resonance itself. The change in energy spectrum and intensity due to the photo-atomic reactions has been quantified using the MCNP6 code and then the NRF self-shielding effect was considered to obtain the spectrums that include all the attenuation factors. Simulations show that when a $^{99}Tc$ target is irradiated at an intensity of the order $10^{17}{\gamma}/s$ for 30 h, 2.01 Ci of $^{99m}Tc$ can be produced.

• 전자공학회논문지D
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• 제36D권3호
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• pp.19-26
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• 1999

자체 설계한 bow-tie 안테나로 구성된 GPR을 이용하여 마른 모래 속에 매설된 파이프의 검출능력을 조사하였다. 송·수신안테나간의 상호결합을 줄이기 위하여 안테나를 차폐구조로 감쌌다. 안테나 끝을 저항으로 종단시켜 유한 길이의 안테나 구조에 의해 발생하는 ringing을 감소시켰다. B-scan 자료에서 쌍곡선 패턴을 구별해 냄으로써 부가적인 신호처리 과정 없이 다양한 매설물들의 존재 유무를 알 수 있었다.