• 한국군사과학기술학회지
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• 제19권4호
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• pp.453-461
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• 2016

The paper represents the experimental analysis of the shock noise of medium caliber guns when a projectile is passed through the shielding material. In the study, the shielding material was constructed and tested in three separate experiments. The shielding material was not installed for medium caliber gun in Case 1. A medium caliber gun was fully covered with shielding material in Case 2, and another one was put with shielding material near muzzle in Case 3. In each experiment, the experimental data was compared with each other. Results showed the firing shielding material achieved a significant noise reduction in $90^{\circ}$ to the noise source. Case 3 is confirmed to be better effective than Case 2 in the near field. But, the noise reduction in the far field is small in quantity due to the low frequency. The paper is considered that further study is necessary for the shielding material which can absorb a low frequency noise in the future.

• 대한방사선기술학회지:방사선기술과학
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• 제42권6호
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• pp.429-434
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• 2019

The gonads are directly affected by radiation exposure during radiography of the pelvis, abdomen, and spine. Exposure of the gonads to radiation can cause genetic mutations and can result in the occurrence of malignant tumors. In this study, we created three types of shielding material shapes for shielding of the ovaries, which are the gonads of female during radiography of the pelvis, and comparative evaluations using shadow shielding methods. The source surface distance(SSD) was 100 cm and the field size was 42 cm × 43 cm. The three types of shielding material shapes(type 1, 2 and 3) were assessed and the entrance surface dose in the ovaries were measured. The thickness of the shielding material was expanded from 0.3 mm to 2.4 mm and after five repetitions, radiation values were measured and mean values were calculated. The mean dose were 3.09 mGy for type 1, 3.54 mGy for type 2, and 3.19 mGy for type 3, indicating that the measurements were the lowest for type 1. When an additional filter of 0.2 Cu + 1 Al was used, the dose were 3.72 mGy for type 1, 5.43 mGy for type 2, and 4.05 mGy for type 3, indicating that the measurements were the lowest for type 1. The results show that, even if the shielding material is not thick, in other words, even with a thickness of 2.94 mGy for the SN 3(0.9 mm) of type 1, shielding can be achieved, with a patient dose lower than the diagnostic reference level(3.42 mGy). Additionally, among the three types of shielding material, the type 1 appeared to be the most appropriate shielding material. It is thought that the use of shielding material could reduce the risk factors for stochastic effects or critical effects of ionizing radiation during pelvic or lumbar radiography.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.624-627
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• 2000

The shielding effectiveness of materials is determined by measuring the ratio of the incident electromagnetic power which passes through the material under test. To measure the shielding effectiveness materials made by conductive polymer, the flanged coaxial transmission-line holder based in ASTM D4935-89, was fabricated. This apparatus has dynamic range between 95dB and 120dB in frequency range of 50Mhz-2Ghz. Furthermore, this system can be utilized to measure the shielding effectiveness of materials produced by conductive polymer and can be adapted for shielding materials design.

• 한국융합학회논문지
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• 제12권6호
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• pp.33-38
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• 2021

경량의 의료방사선 차폐시트를 제작하기 위해 새로운 차폐소재를 검토하였다. 가정에서 음식물 쓰레기로 버려지는 계란 껍데기 분말을 고분자 물질과 혼합하여 차폐재료의 가능성을 검증하고자 하였다. 기존의 경량 소재는 친환경의 조건을 만족하지만 주 재료 정제과정의 비용으로 인해 차폐시트 제작의 경제성에 어려움이 있다. 본 연구는 가정용 폐기물인 계란 껍데기를 이용하여 이러한 문제점을 해결하고자 한다. 고분자 물질인 HDPE를 이용하여 3 mm 두께의 차폐시트를 제작하였으며, 차폐시트 단면 내의 입자 분포상태도 분석하였다. 입자의 모양은 대체로 거칠게 구성되어 입자 간 공극이 있었으며, 단위 면적당 무게는 평균 1.5 g/cm² 로 나타났다. 차폐성능은 저에너지 영역에서는 20%대, 고에너지 영역에서는 10%대의 차폐성능을 보여 저선량 의료방사선 차폐시트의 재료로 가능성을 보여주었다.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2387-2393
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• 2020

In this study, a gradient material for shielding neutrons and gamma rays was developed, which consists of epoxy resin, boron carbide (B₄C), lead (Pb) and a little graphene oxide. It aims light weight and compact, which will be applied on the transportable nuclear reactor. The material is made up of sixteen layers, and the thickness and components of each layer were designed by genetic algorithm (GA) combined with Monte Carlo N Particle Transport (MCNP). In the experiment, the viscosities of the epoxy at different temperatures were tested, and the settlement regularity of Pb particles and B₄C particles in the epoxy was simulated by matlab software. The material was manufactured at 25 ℃, the Pb C and O elements of which were also tested, and the result was compared with the outcome of the simulation. Finally, the material's shielding performance was simulated by MCNP and compared with the uniformity material's. The result shows that the shielding performance of gradient material is more effective than that of the uniformity material, and the difference is most noticeable when the materials are 30 cm thick.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.73-79
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• 2001

In this paper, shielding effectiveness(SE) of the shielding material of electromagnetic(EM) waves was investigated with actual experiments. The materials used in this study were made up of sputtering, film and powder of conductive materials - Cr, Al, Ag and Cu etc. Also, the polyester film was used as a base material. The experiment was carried out by using a shielding evaluator(Shielding box) TR17302 with an ADVANTEST spectrum analyzer, model R3361C. It was found from the experimental results that silver, copper, aluminum and chromium were good candidates as a shielding material against the EM waves with increasing the SE as the composite was laminated. The characteristics of the SE against the EM waves depended on a mode of preparation of specimen. The effects of density of particles on the SE were studied when the sputtering. The SE strongly depended on the electric resistance by density of sputtering and painting particles. SE increased as the density of particles was increasing.

• 한국방사선학회논문지
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• 제16권5호
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• pp.527-536
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• 2022

본 연구는 우주방사선 차폐물질 설계를 위한 선행연구 차원에서 우주방사선에 대한 물질별 방사선 차폐특성을 분석하였다. 특히 EMP 및 방사선 차폐에 효과가 있다고 알려진 경량 연자성 복합소재에 대한 우주방사선 차폐물질 활용 가능성을 확인하고자 하였다. 이를 위해 Monte Carlo N-Particle(MCNP) 모델링 기법과 열중성자 차폐실험을 수행하였으며, MCNP의 우주방사선 모델인 Skymap.dat를 활용하였다. 연구결과 폴리에틸렌, 붕소폴리에틸렌, 탄소나노튜브 등 탄소와 수소를 함유한 물질의 경우 증발 중성자 에너지 영역 대 이하의 중성자 감소에 효과적인 것으로 나타났으며 SS316, 경량 연자성 물질 등 철을 함유한 물질은 캐스케이드 중성자 차폐성능이 뛰어난 것을 확인할 수 있었다. 특히 경량 연자성 물질의 경우 붕소를 함유하고 있어 저속중성자 영역의 중성자 감소에도 효과적인 것으로 나타났으며, 향후 탄소 및 수소 등 탄성산란 물질을 보강한다면 우주방사선 중성자 전 영역에서 유의미한 차폐효과를 보여줄 것으로 기대된다.

• 한국방사선학회논문지
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• 제15권2호
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• pp.191-199
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• 2021

본 연구의 목적은 경량 연자성 소재의 방사선 차폐 효과를 분석하여 군사시설에 대한 적용 가능성을 확인하는 것이다. 연자성 물질은 EMP 차폐에 효과적인 것으로 알려져 있다. 이 물질이 방사선 차폐에도 효과적이라면 군 방호에 효과적으로 적용이 가능할 것으로 예상된다. 이에 본 연구에서는 감마선 차폐 효과를 확인하기 위해 Cs-137 및 Co-60 선원을 사용하여 실험을 수행하였으며, 중성자 차폐 효과를 평가하기 위해 Monte Carlo N-Particle (MCNP) 모델링을 적용하였다. 그 결과 연자성 소재의 두께가 증가함에 따라 감마선과 중성자의 선형 감쇠 법칙에 의한 차폐성능이 향상됨을 확인할 수 있었다. 따라서 연자성 소재를 군사용 구조물 등에 적용할 경우에 방사선 차폐에 효과적이라는 것을 확인하였다.

• 품질경영학회지
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• 제43권3호
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• pp.239-252
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• 2015

Purpose: Lead has been widely used in radiation shielding for its low price and high workability. Recently in several europe countries, use of lead was banned for environmental issues. Also lead can cause health problems like alergies. Alternative materials for lead are highly required. The purpose of this study was to propose lead free radiation shielding material. Methods: Research of radiation shielding in Korea is not easy for certain limits such as radiation materials, experimental facilities and places. The collected data through the research were simulated using MCNPX. The simulation tools used for this study were utilized Monte Carlo method. Results: we suggest new design of lead free radiation shielding material using MCNPX code comparing shielding performance of new composite materials to lead. Conclusion: This newly introduced nano-scale composite of metal and polymer makes new chance for highly lightened radiation protective garments with endurable shielding performance.

• 대한기계학회논문집A
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• 제23권6호
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• pp.1048-1054
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• 1999

It is important to study the shielding effectiveness(SE) of reinforcing material of plastic composite materials against the electromagnetic(EM) waves. In this paper, SE of the shielding material of EM waves was investigated with actual experiments. The materials used in this study were made up of film, fiber and powder of conductive materials - Cu, Al, CF etc. Also, The resin film was used as matrix. The experiment was carried out by using a shielding evaluator(Shielding box) TR17302 with an ADVANTEST spectrum analyzer, model R3361C. It was found from the experimental results that copper, aluminum and carbon fiber were good candidates as a shielding material against the EM waves with increasing the SE as the composite was laminated. The characteristics of the SE against the EM waves depended on a mode of preparation of specimen. The effects of interval of wires on the SE were studied when the orientation and the space of Cu wires were changed. The SE strongly depended on the. orientation and the space of the Cu wire. SE decreased as the space of the Cu wires was increasing.