• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.350-353
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• 2009

The shielding enclosure is very essential device to test the electromagnetic wave power generated by various RF equipments. Some standards for the shielding enclosures were established to test them in right method. Generally, There are IEEE-STD-299 and MIL-STD-285 and NSA-65-6 of the method for measuring the effectiveness of shielding enclosures, the IEEE-STD-299 combined MIL-STD-285 and NSA-65-6 about the method for measuring shielding effectiveness(SE) about 1969 years, but, the measurement point of 299 proposal is many points(including shielding wall, seam, coner beat, shielding door, etc) and demand long time of measurement. To improve SE test method for shielding enclosures was studied and suggested to develop a proper test procedure. First, we measure reference level as frequency range and H/V polarization, secondly, measure leakage point, and finally, measure shield effect and calculate SE. Our method has a merit of the less measurement point than IEEE-STD-299, and shorten time than 299, and define representation SE of shielding enclosure effectively.

• 한국산학기술학회논문지
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• 제21권12호
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• pp.67-76
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• 2020

본 연구는 고출력 전자기파(EMP)를 차폐할 수 있는 콘크리트의 개발 방향과 차폐성능 평가방법의 표준화에 필요한 기술의 개발 방향을 도출하기 위한 목적으로 수행되었다. 콘크리트와 같은 복합재료를 대상으로 한 EMP 차폐 메커니즘은 아직 규명되지 않았고, 콘크리트 재료의 EMP 차폐성능에 대한 검증 방법도 아직 표준화가 되어 있지 않아, 연구자간의 연구결과를 객관적으로 상호 비교분석하는데 어려움이 발생한다. EMP 차폐 콘크리트의 개발 방향은 금속 분야에서 널리 알려진 전자파 손실 메커니즘의 고찰로부터 도출하였다. 콘크리트의 EMP 차폐성능 검증을 위한 표준화 방향은 콘크리트의 전기적 성질과 그 동안 콘크리트를 대상으로 연구한 차폐성능 평가방법들의 고찰로부터 도출하였다. 연구 결과, EMP 차폐 콘크리트 개발은 전기 전도성을 부여한 콘크리트의 재료개발이 우선하여야 하며, EMP 차폐 콘크리트의 재료개발 과정 중에는 전자파 손실 메커니즘별로 구분한 시험방법을 적용하고, 개발 제품의 최종 품질검증에는 일반화된 차폐성능 평가법(MIL-STD 등)을 준용한 시험법을 적용하면, 유효성이 입증된 콘크리트 차폐재 개발 및 성능평가가 가능할 것으로 판단된다.

• 조명전기설비학회논문지
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• 제27권10호
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• pp.30-40
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• 2013

In this study the method based on flux linkage in cell was introduced in calculation of eddy currents by cell method. According to this method eddy current distribution and the loss can be evaluated and since the shielding effectiveness by flux cancelation of eddy current can be analyzed, this method is applicable to design of conductive shield. And also the formula of shielding factor were so deduced as to be applicable to finite-width infinite-length shielding sheets and infinite-length underground cable shield. These formula are adaptable to magnetic materials as well as conductive materials. As the results of calculation in model shields are follows. In case of finite-width infinite-length shielding sheet, shielding effectiveness increases with increasing of conductivity. In case of infinite-length underground cable shield, the effectiveness become higher with increasing of permeability. Especially the effectiveness is very high in materials with both high conductivity and permeability in underground cable shield.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.18-19
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• 2020

The ElectroMagnetic Pulse (EMP) destroys social infrastructure at once and causes social chaos. However, currently major infrastructures are constructed of concrete that does not have electromagnetic shielding performance. In this study, using the arc metal spraying method is used to evaluate the shielding performance and construction performance of concrete. The electro-magnetic shielding effect is measured by fabricating a shielding room with reference to MIL-STD-188-125, and the construction performance is evaluated by measuring the adhesion strength of thin metal sprayed film-concrete. As a result of the study, when the metal spraying method is applied, the shielding effect is higher than that of the special electro-magnetic shielding concrete, and it is considered to be more economical than the existing metal plate (3~5 mm).

• 전기학회논문지
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• 제60권4호
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• pp.694-699
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• 2011

This paper compares the performance of lightning shielding analysis methods using the seven striking distance formulae in substation. For comparison, we evaluate the number of expected strikes and exposed area using WinIGS Software. Seven striking distance formulae are compared using the electrogeometric model analysis and the rolling sphere method. Based on the electrogeometric model analysis, the risk of shielding failure in either the whole substation or parts of it is determined. According to the simulation results, one can justify whether the substation satisfies the criterion of shielding design. In particular, according to the rolling sphere method, the exposed areas in substation determine the location of the additional shielding poles or shield wires. Therefore, the installation of the additional shielding poles and shield wires in substation was accepted by shield design at the phase conductors exposed in the larger area.

• Journal of Magnetics
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• 제20권2호
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• pp.103-109
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• 2015

In this study, the authors attempted to produce a medical radiation shielding fiber that can be produced at a nanosize scale and that is, unlike lead, harmless to the human body. The performance of the proposed medical radiation shielding fiber was then evaluated. First, diamagnetic bismuth oxide, an element which, among elements that have a high atomic number and density, is harmless to the human body, was selected as the shielding material. Next, 10-100 nm sized nanoparticles in powder form were prepared by ball milling the bismuth oxide ($Bi_2O_3$), the average particle size of which is $1-500{\mu}m$, for approximately 10 minutes. The manufactured bismuth oxide was formed into a colloidal solution, and the radiation shielding fabric was fabricated by curing after coating the solution on one side or both sides of the fabric. The thicknesses of the shielding sheets prepared with bismuth oxide were 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 1.0 mm. An experimental method was used to measure the absorbed dose and irradiation dose by using the lead equivalent test method of X-ray protection goods presented by Korean Industrial Standards; the resultant shielding rate was then calculated. From the results of this study, the X-ray shielding effect of the shielding sheet with 0.1 mm thickness was about 55.37% against 50 keV X-ray, and the X-ray shielding effect in the case of 1.0 mm thickness showed shielding characteristics of about 99.36% against 50 keV X-ray. In conclusion, it is considered that nanosized-bismuth radiation shielding fiber developed in this research will contribute to reducing the effects of primary X-ray and secondary X-ray such as when using a scattering beam at a low level exposure.

• 대한방사선기술학회지:방사선기술과학
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• 제46권6호
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• pp.543-551
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• 2023

In this study, the aim was to assess the shielding performance of different 3D printing materials, specifically those produced using FDM, SLA, and CJP methods, with a focus on their application as shielding devices in clinical settings. Additionally, the weight of lead shielding materials can evoke reluctance in pediatric patients undergoing X-ray imaging. A total of 12 materials were printed using their respective 3D printers. These materials were then subjected to X-ray testing using diagnostic X-ray equipment and an exposure meter. The goal was to evaluate their shielding capabilities in comparison to 1 mm lead. The results of this evaluation revealed that VisiJet PXL-Pastel, produced using the CJP method, exhibited the highest shielding performance. Therefore, VisiJet PXL-Pastel by CJP method was selected for the creation of a shielding device designed for pediatric reproductive organs. Subsequent tests demonstrated that both the newly created shielding device and conventional lead shielding equipment achieved the same maximum shielding rate at 50 kVp. Specifically, the shielding rate for the 3D printed device was measured at 84.53%, while the conventional lead shielding equipment, categorized as Apron1 (85.74%), Apron2 (99.98%), and Apron3 (99.04%), demonstrated similar performance. In conclusion, the CJP-produced VisiJet PXL-Pastel material showcased excellent radiation shielding capabilities, allowing for anatomical observations of the target organs and their surrounding structures in X-ray images. Furthermore, its lower weight in comparison to traditional lead shielding materials makes it a clinically practical and useful choice, particularly for pediatric applications.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.749-755
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• 2023

A new approximation method was proposed for treating the non-resonant spatial self-shielding effects of double heterogeneous region such as the double heterogeneous effect of VHTR fuel compact in the thermal energy range and that of BP compact with BISO. The method was developed based on the effective homogenization method and a spherical unit cell model with explicit coated layers and a matrix layer. The self-shielding factor was derived from the relation between the collision probabilities for a double heterogeneous compact and the effective cross section for the homogenized compact. First, the collision probabilities and transmission probabilities for all layers of the spherical model were calculated using conventional collision probability solver. Then, the effective cross section for the homogenized sphere cell representing the homogenized compact was obtained from the transmission probability calculated using the probability density function of a chord length. The verification calculations revealed that the proposed method can predict the self-shielding factor with a maximum error of 2.3% and the double heterogeneous effect with a maximum error of 200 pcm in the typical VHTR problems with various packing fractions and BP compact sizes.

• 대한방사선기술학회지:방사선기술과학
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• 제37권2호
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• pp.143-150
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• 2014

몬테칼로 모사를 이용하여 베타선으로부터 발생되는 제동복사선과 이로 인해 받는 선량을 비교 분석 하고자 하였으며, 방사선 차폐에 이용하는 납치마를 이용하여 실제 I-131 치료병실에서 발생되는 방사선의 감쇠정도를 비교하고자 하였다. 몬테칼로 모사를 이용하여 납 또는 물로 구성된 차폐체를 설정하여 베타선의 상호작용에 대한 스펙트럼을 분석하였으며, 납치마를 기준으로 0.25 mm 와 0.5 mm의 납 설정과 물 0.1 mm 와 0.2 mm를 설정하여 납만을 이용한 차폐방법과 물과 납을 두 가지를 이용한 차폐실험을 진행하였다. 실험 결과 납 두께 0.5 mm로 차폐 시 선량이 물과 납을 이용한 2차 차폐 방법을 사용했을 때와 유사하게 나타났으며, 납 0.25 mm 만을 사용했을 때 차폐효과가 다소 낮았지만, 납 차폐체가 없는 때의 선량에 비해 약 60% 감소효과를 나타냈다.

• 한국인터넷방송통신학회논문지
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• 제19권3호
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• pp.59-65
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• 2019

마그네틱 프로브와 노이즈 소스의 근거리장에 금속 차폐막이 놓여있을 때 차폐막 두께에 따른 EMI 차폐효과를 분석하였다. 노이즈 소스로는 마이크로스트립 라인을 이용하였으며, 금속 차폐막 재료로는 그래파이트와 페라이트를 선정하였다. 마그네틱 프로브는 IEC 61967-6 방식을 적용하여 마그네틱 프로브를 이용한 전자기 방사 측정 방법을 사용하였다. 마이크로스트립 라인과 마그네틱 프로브 사이의 투과계수를 분석하였고, 둘 사이의 거리는 단일 차폐막일 경우 1 mm, 다중 차폐막일 경우 5 mm로 수행하였다. 차폐막의 두께는 5 um, 10 um, 30 um, 50 um 으로 변화시켰다. 주파수를 150 kHz에서 1 GHz까지 변화시켰을 경우 최대 44.9 dB의 SE(Shielding Effectiveness)를 얻었다.