EMP 방호용 철근콘크리트의 취약대역 보완을 위한 두께 및 도료 적용 방법 연구

장홍제,최명렬 한국전자파학회 2024 한국전자파학회논문지 Vol.34 No.2

무선 제어, 자동화, 통신의 사용이 증가함에 따라 기반시설은 전자기 공격에 점점 더 취약해지고 있다. 기존에는 금속차폐실을 설치하여 인프라를 보호하였다. 그러나 차폐실 구축은 비용이 많이 들고, 공간 비효율성, 유지 관리 등의 단점이 있다. 이 문제를 해결하기 위해 콘크리트에 차폐 재료를 첨가하는 방법이 연구되고 있다. 본 논문에서는 기존의 철근콘크리트와 차폐 철근 콘크리트의 전자기적 특성을 비교하였다. 먼저 시뮬레이션으로 구조물에 대한 차폐효과를 예측하였다. 그 중 차폐 콘크리트는 자갈을 전기로에서 발생한 산화철 슬래그로 대체하였으며, 차폐효과를 측정하기 위해MIL-STD-188-125-1을 참고하였다. 기존 콘크리트의 차폐효과는 100∼300 MHz 주파수 대역에서 낮게 나타나며, 이러한특성은 차폐 철근 콘크리트에도 영향을 미치게 되어 낮은 차폐효과가 나타난다. 따라서, 차폐 콘크리트 구조물의 취약주파수 대역을 보완하는 방법이 제안되었다. 그 방법은 차폐 재료를 함유한 수용성 도료를 도포하고 콘크리트의 두께를증가시키는 방법이다. 특히 제안된 보완 방법은 사람의 안전에 초점을 맞추고 건물의 건설 과정에 미치는 영향을 최소화하는 것을 목표로 한다. 그리고 보완 방법을 적용한 콘크리트 구조물의 차폐효과를 측정하였다. 제안된 보완 방법은 주요 인프라에 60 dB 이상의 차폐효과가 나타나는 것이 검증되었다. Building infrastructure is becoming increasingly vulnerable to electromagnetic attacks with increasing use of wireless control, automation, and telecommunication. Infrastructure can be protected by installing shielded rooms constructed of metal. However, such rooms are expensive to build and have disadvantages including space ineffectiveness and maintenance. Developing methods to add shielding materials to the concrete can help solve the problem. In this paper, we compare the electromagnetic properties of traditional reinforced concrete and shielding-reinforced concrete. Based on the simulation results, structures were built and the shielding effectiveness was measured. The shielding concrete was prepared by replacing the gravel with ferrous oxide slag from electric arc furnaces; MIL-STD-188-125-1 was referenced to measure the shielding effectiveness. The shielding effectiveness of traditional concrete and con- crete reinforced with shielding is low in the frequency band of 100∼300 MHz. Thus, methods to improve the shielding effectiveness of shielding-concrete structures were proposed. The methods include applying water-soluble paint containing shielding materials and in- creasing the concrete thickness, focusing on safety and minimizing the impact on building construction. The shielding effectiveness of concrete structures using these methods was measured. The proposed solution was determined to be realistic, with a shielding effective- ness exceeding 60 dB for major infrastructure.

EMP 방호용 철근콘크리트의 취약대역 보완을 위한 두께 및 도료 적용 방법 연구

장홍제(Hongje Jang),최명렬(Myungryul Choi) 한국전자파학회 2024 한국전자파학회논문지 Vol.35 No.2

유방촬영 시 비스무스를 이용한 새로운 차폐복의 차폐효과와 유용성 연구

권지혜,김유성,김혁,장수진,정선주,서선열,유수정 대한안전경영과학회 2014 대한안전경영과학회 학술대회논문집 Vol.2014 No.11

In this study, mammography was conducted with Lorad Selenia from HOLOGIC. The phantoms used were Female rando phantom from THE PHANTOM LABORATORY and ACR phantom from GAMMEX RMI. The dosimeters used were the glass dosimeter reader FDG1000 and PLD from CHIYODA TECHNOL. The shielding used to compare and determine the amount of scattered ray in this study were lead shielding gear with a thickness of 0.25mm from INFAB and a customized bismuth shielding with a thickness of 0.2mm(2 layers of 0.1mm). The conditions were 28kVp, 65mAs for CC view and 30kVp, 85mAs for MLO view. The exposure dose by scattered ray were measured from thyroid, breast on the opposite side and gonad (hereafter called critical organs) without any shieldings for the first experiment, then measured four times each with lead shielding for the next experiment, and measured four times each with bismuth shielding for the third experiment. The average dose for each critical organ without shieldings were 135.75μGy, 649.67μGy and 546.25μGy, With lead shielding, the numbers were 0μGy, 63μGy and 1.5μGy, and 6.25μGy, 12.25μGy and 26.5μGy with bismuth shielding. Therefore, the lead and bismuth shielding have reduced 95.364% and 93.550% of exposure dose. Use of shielding s during mammography reduces the exposure dose on critical organs and other organs of the patient, and despite the similar shielding rate, the new shielding using bismuth is useful in shielding thyroid and gonad considering the mobility of the patient, light weight and thickness of the shielding.

실리콘 혼합 차폐체의 개발과 성능비교

정회원(Hoi-Woun Jeong),민정환(Jung-Whan Min) 대한방사선과학회(구 대한방사선기술학회) 2023 방사선기술과학 Vol.46 No.3

A shield was made by mixing materials such as bismuth(Bi) and barium(Ba) with silicon to evaluate its shielding ability. Bismuth was made into a shield by mixing a bismuth oxide(Bi2O3) colloidal solution and a silicon base and applied to a fibrous fabric, and barium was made by mixing lead oxide(PbO) and barium sulfate(BaSO4) with a silicon curing agent and solidifying it to make a shield. The test was conducted according to the lead equivalent test method for X-ray protective products of the Korean Industrial Standard. The experiment was conducted by increasing the shielding body one by one from the test condition of 60 kVp, 200 mA, 0.1sec and 100 kVp, 200 mA, 0.1 sec. At 60 kVp, 2 lead oxide-barium sulfate shields, 2 bismuth oxide 1.5 mm shields, and 5 bismuth oxide 0.3 mm shields showed shielding ability equal to or higher than that of lead 0.5 mm. At 100 kVp, 2 lead oxide-barium sulfate shields and 2 bismuth oxide 1.5 mm shields showed shielding ability equal to or higher than that of lead 0.5 mm. It was confirmed that when using 2 pieces of lead oxide-barium sulfate and 1.5 mm of bismuth oxide, respectively, it has shielding ability equivalent to that of lead. Bismuth oxide and lead oxide-barium sulfate are lightweight and have excellent shielding ability, thus they have excellent properties to be used as an apron for radiation protection or other shielding materials.

Total Shielding Efficiency, Reflection Loss and Absorption Loss of Nanoparticles/Paraffin Wax Absorber in the Shielding of Electromagnetic Pollution

Rohollah Fallah Madvari,Sedigheh Hosseinabadi,Hamideh Bidel,Gholamhossein Pourtaghi,Fereydoon Laal 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.6

The extensive development of diverse electronic/electrical systems has led to increased exposure to electromagnetic field and can result in many adverse effects on humans, other living beings, safety operation of various equipment, etc. Electromagnetic interference (EMI) shielding materials are in greater demand to suppress this electromagnetic pollution. The present study investigates the factors affecting the shielding effi ciency of carbon black-based nanocomposite shields. Fe3O4/carbon black nanocomposite (CBN) with paraffi n wax were fabricated by melt mixing methods in different weight percentages of the dispersants. The EMI shielding properties of the nanocomposites were measured using a vector network analyzer in the frequency range of 8.2 to 12.5 GHz (X band) based on the transfer/reflection method. The total shielding efficiency was used to assess the shield's protection performance. Based on the weight percentages of nanocomposite constituents, four samples were obtained. The highest average of total shielding effi ciency in equal thickness belonged to the sample with 50% CBN and 15% Fe3O4 nanoparticles in weight. At different thicknesses, the highest average total shielding efficiency was related to the minimum thickness of 0.8 mm. Also, in with increasing the frequency decreased the mean total shielding efficiency in the samples. Depending on the type and weight percentage of nanocomposite compounds, one of the absorption or reflection mechanisms can be the main mechanism in reducing or eliminating electromagnetic waves in nanocomposite shields. The shield thickness and frequency of electromagnetic waves aff ect the protective performance of the shield.

텅스텐 차폐체의 감마선 투과선량 측정

한상현(Sang-Hyun Han),구본열(Bon-Yeoul Koo) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.9

본 연구는 Apron의 재질로 이용되고 있는 텅스텐 차폐체를 핵의학과에서 사용하는 선원의 종류와 차폐체의 두께, 선원부터 검출기 사이의 거리를 변화시켜 차폐체에 투과시킨 후 투과선량과 차폐율을 알아보고자 하였다. 실험을 위해서 선원과 차폐체와 검출기를 일직선으로 배치하고 높이 100 ㎝ 지점에서 Inspector로 측정하였다. 그 결과 텅스텐에 차폐효과가 가장 높은 선원은 <SUP>201</SUP>Tl 선원으로 측정되었고, <SUP>123</SUP>I 선원이 <SUP>99m</SUP>Tc 선원보다 차폐효과가 높게 나타났다. 실험에 사용한 선원과 검출기 사이의 거리는 멀어질수록 투과선량은 작아졌고, 텅스텐 차폐체의 두께는 두꺼울수록 차폐율은 높게 측정되었다. 하지만 <SUP>13</SUP>1I와 <SUP>18</SUP>F 선원에서는 0.25 ㎜Pb의 차폐체를 사용했을 경우 차폐체가 없을 경우 보다 차폐율이 감소하는 것을 확인하였다. 따라서 <SUP>13</SUP>1I와 <SUP>18</SUP>F 선원을 사용할 경우에는 방사선 차폐효과가 높은 텅스텐일지라도 선원의 종류에 따른 특성과 차폐체의 두께를 고려하여 사용하길 권장하고, 실험 결과를 참고하여 사용한다면 피폭 저 감화방안에 도움을 줄 수 있을 것으로 생각된다. This study was conducted to investigate the penetration dose and shielding rates of tungsten shields used in apron material by changing the type of source used in the nuclear medicine department, thickness of shielding material and distance between the source and detector. For the experiment, the source, shield, and detector were arranged in a straight line and measured with an inspector at a height of 100 ㎝. The highest shielding effect of tungsten was measured for <SUP>201</SUP>Tl, while <SUP>123</SUP>I showed a higher shielding effect than <SUP>99m</SUP>Tc. For the sources used in the experiment, the penetration dose decreased with distance and the shielding rate was measured with thicker thickness. However, the shielding rate of <SUP>13</SUP>1I and <SUP>18</SUP>F sources was found to be lower than when there was no shielding at 0.25 ㎜Pb shield. Therefore, even if the radiation shielding effect of tungsten is high, considering the characteristics according to the type of source and the thickness of the shielding material, it may be helpful to reduce the exposure.

6 MV 선형가속기의 치료실에 설치되는 직접차폐식 도어의 차폐 두께 계산식에 관한 연구

박철서(Cheol Seo Park),김종언(Jong Eon Kim),강은보(Eun Bo Kang) 한국방사선학회 2020 한국방사선학회 논문지 Vol.14 No.5

이 연구의 목적은 NCRP 보고서 151과 IAEA 안전 보고서 시리즈 47 기반으로 직접차폐식 도어의 납 두께 계산식을 유도하는 데 있다. 직접차폐식 도어에서 선량률 계산식을 유도한 후, 이 식을 납 차폐 두께 계산식에 대입하여 도어에서 차폐 두께 계산식을 유도하였다. 유도된 직접차폐식 도어의 차폐 두께 계산식으로부터 계산된 납 차폐 두께는 NCRP 및 IAEA 2차 방벽 차폐 두께 계산 방법으로 산출된 두께보다 약 6% 낮았다. 이 결과는 NCRP 및 IAEA 2차 방벽 차폐 두께 계산 방법으로부터 두께 계산이 더 보수적이고 2차 빔 차폐에 잘 맞는다는 의미로 해석된다. 결론적으로, 이 연구에서 유도된 직접차폐식 도어의 납 차폐 두께 계산식은 도어의 차폐 설계에 유용하게 사용될 수 있을 것으로 사료된다. The purpose of this study is to derive a lead thickness calculation formula for direct-shielded doors based on NCRP Report No.151 and IAEA Safety Report Series N0.47. After deriving the dose rate calculation formula for the direct shielded door, this formula was substituted for the lead shielding thickness calculation formula to derive the shielding thickness calculation formula at the door. The lead shielding thickness calculated from the derived direct shielded door shielding thickness calculation formula was about 6% lower than that calculated by the NCRP and IAEA secondary barrier shielding thickness calculation methods. This result is interpreted as meaning that the thickness calculation is more conservative from the NCRP and IAEA secondary barrier shielding thickness calculation methods and fits well for secondary beam shielding. In conclusion, it is thought that the formula for calculating lead shielding thickness of the direct shielded door derived in this study can be usefully used in the shield design of the door.

고 에너지 양성자 가속기에서 생성되는 2차 방사선의 효과적인 차폐에 관한 연구

배상일(Sang-Il Bae),김정훈(Jung-Hoon Kim) 대한방사선과학회(구 대한방사선기술학회) 2020 방사선기술과학 Vol.43 No.5

High-energy proton accelerators continue to be increasingly used in medical, research and industrial settings. However, due to the high energy of protons, a large number of secondary radiation occurs. Among them, neutrons are accompanied by difficulties of shielding due to various energy distribution and permeability. So In this study, we propose a shielding method that can shield neutrons most efficiently by using multiple-shielding material used as a decelerating agent or absorbent as well as a single concrete shielding. The flux of secondary neutrons showed a greater decrease in the flux rate when heavy concrete was used than in the case of ordinary concrete, and the maximum flux reduction was observed at the front position when using multiple shields. Multiple shielding can increase shielding efficiency more than single shielding however, As the thickness of the multiple shielding materials increased, the decline in flux was saturated. The mixture material showed higher shielding results than the polyethylene when using boron carbonate.

소아의 식도 상복부위장관조영검사에서 생식선 차폐 유무에 따른 생식선량에 관한 연구

노현아(Hyun-A Noh),김민정(Min-Jeong Kim),박은성(Eun-Seung Park),성민숙(Min-Sook Sung),하동윤(Dong-Yoon Ha) 대한영상의학기술학회 2012 대한영상의학기술학회 논문지 Vol.2012 No.-

목적: 본 연구는 소아의 하복부 전체를 감싸는 랩스커트 형식의 차폐도구를 제작하여 소아의 식도조영검사와 상복부위장관조영검사에서 실험을 통해 생식선 차폐 유무에 따른 생식선의 흡수선량의 변화를 알아보고, 이를 줄일 수 있는 방안을 알아보고자 하였다. 방법: 2011년 1월부터 3월까지 본원에서 식도조영검사와 상복부위장관조영검사를 시행한 소아 50명을 대상으로 검사 중 평균 투시시간과 저격촬영의 수를 알아보았다. 파악된 평균 투시시간은 331.5초와 촬영된 영상은 18장이었으며 이를 적용하여 소아팬텀과 유리선량계를 이용하여 생식선이 포함되지 않도록 조사영역을 설정한 후 생식선 차폐 유무에 따른 생식선의 흡수선량을 비교하였다(협조군). 또한 협조가 어려운 소아를 고려하여 위의 파악된 투시시간과 저격촬영의 수의 1/10의 조건으로 생식선이 포함되도록 조사영역을 설정한 후생식선 차폐 유무에 따른 생식선의 흡수선량을 비교하였다(비협조군). 결과: 1. 협조군의 생식선 흡수선량 결과 협조군의 경우 생식선 차폐 유무에 따른 흡수선량 결과, 차폐를 시행하였을 경우 난소 99.5 µGy, 자궁 84 µGy, 전립선 33 µGy, 정낭 15 µGy로 나타났다. 차폐를 하지 않았을 경우 112.5 µGy, 자궁 86.5 µGy, 전립선 34 µGy, 정낭 28 µGy로 생식선 차폐 시행으로 난소, 자궁, 전립선에서의 선량 변화는 미미했으나, 정낭의 경우 약 46.4%의 선량감소를 보였다. 2. 비협조군의 생식선 흡수선량 결과 비협조군의 경우 생식선 차폐 유무에 따른 흡수선량 결과, 차폐를 시행하였을 경우 난소 262 µGy, 자궁 201.5 µGy, 전립선 67 µGy, 정낭 40.5 µGy로 나타났다. 차폐를 하지 않았을 경우 난소 767 µGy, 자궁은 512 µGy, 전립선은 787 µGy, 정낭 1429 µGy로 나타나차폐를 시행하였을 때보다 난소는 약 3배, 자궁은 약 2.5배, 전립선은 약 12배, 정낭은 약 35배나 높게 나타났으며 생식선 차폐 시행으로 무려 약 61~97%의 선량감소를 보였다. 결론: 소아의 식도 위장조영검사 시 생식선 피폭을 줄이기 위해서는 관심부위만 조사영역을 최소화하여 검사를 진행함과 동시에 생식선 차폐라는 보다 적극적이면서도 각별한 노력이 수반될 때 소아의 생식선 피폭을 줄일 수 있을 것으로 생각된다. Purpose: We studied pediatric absorbed dose while performing the pediatric esophagography and upper gastrointestinal series using gonadal shielding. Materials and Methods: We recorded pediatric absorbed dose of gonad during the esophagography and upper gastrointestinal series from January 2011 to March 2011. And we recorded average fluoroscopic time and spot images of 50 pediatric patients. It wes measured such as 331.5s and 18 images. We used pediatric phantom and radiophotoluminescent Glass Rod Detector (GRD). First area of field was to include the gonads (cooperation). Second area of field was not to include the gonads considering active pediatrics (noncooperation). By applying the measured values, we compared absorbed does of gonad according to existence of gonadal shielding. Results: 1. Cooperation : Absorbed dose of gonads was measured on 99.5 μGy (ovary), 84 μ Gy (uterus), 33 μGy (prostate) and 15 μGy (seminal vesicle) include gonadal shielding. On the contrary without gonadal shielding, absorbed dose was measured on 112.5 μGy (ovary), 86.5 μGy (uterus), 34 μGy (prostate) and 28 μGy (seminal vesicle). Result of comparison of the absorbed dose seminal vesicle with gonadal shielding was reduced more than without that (46.4%). 2. Noncooperation : Absorbed dose of gonads was measured on 262 μGy (ovary), 201.5 μGy (uterus), 67 μGy (prostate) and 40.5 μGy (seminal vesicle) include gonadal shielding. On the contrary without gonadal shielding, the absorbed dose was measured on 767 μGy (ovary), 512 μGy (uterus), 787 μGy (prostate) and 1429 μGy (seminal vesicle). Result of comparison of absorbed dose with gonadal shielding was reduced more than without that (61~97%). The absorbed dose of ovary, uterus, prostate with shielding was reduce more than 4.5~12 times.Conclusion: Operators should examine pediatric fluoroscopy examinations to reduce patient’s dose by minimizing the area of field and using gonadal shielding for gonadal dose reduction.

Development and application analysis of high-energy neutron radiation shielding materials from tungsten boron polyethylene

Shao Qiankun,Zhu Qingjun,Wang Yuling,Kuang Shaobao,Bao Jie,Liu Songlin 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.6

The purpose of this study is to develop a high-energy neutron shielding material applied in proton therapy environment. Composite shielding material consisting of 10.00 wt% boron carbide particles (B4C), 13.64 wt% surface-modified cross-linked polyethylene (PE), and 76.36 wt% tungsten particles were fabricated by hotpressure sintering method, where the optimal ratio of the composite is determined by the shielding effect under the neutron field generated in typical proton therapy environment. The results of Differential Scanning Calorimetry measurements (DSC) and tensile experiment show that the composite has good thermal and mechanical properties. In addition, the high energy-neutron shielding performance of the developed material was evaluated using cyclotron proton accelerator with 100 MeV proton. The simulation shows a 99.99% decrease in fast neutron injection after 44 cm shielding, and the experiment result show a 99.70% decrease. Finally, the shielding effect of replacing part of the shielding material of the proton therapy hall with the developed material was simulated, and the results showed that the total neutron injection decreased to 0.99‰ and the neutron dose reduced to 1.10‰ before the enhanced shielding. In summary, the developed material is expected to serve as a shielding enhancement material in the proton therapy environment.