• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.49-55
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• 2020

In order to improve the electromagnetic shielding rate of Carbon Fiber (CF), it was produced using the nickel nano-powder impregnating method. Using two types of nickel powder having thicknesses of 50 ㎛ and 100 ㎛, and a thermoplastic elastomer resin, a compound containing 10-20% nickel content was mixed and then manufactured through an extruder. The CF coated with the compound was woven and manufactured using a 1-ply specimen. The final nickel content of the specimen was verified using TGA and the distribution of nickel powder on the CF surface was verified using SEM. The metal shows a high shielding rate in the low-frequency band, but the shielding rate decreases at higher-frequency bands. The CF improves at the higher frequency band, and metals reflect electromagnetic waves while carbon absorbs electromagnetic waves. The study of shielding materials, which are stronger and lighter than metal, by using CF lighter than metal and enabling the shielding rate from low-frequency band to high-frequency band, confirmed that the larger the area coated with nickel nano-powder, the better the electromagnetic shielding performance. In particular, CF coated with a thickness of 100 ㎛ has a shielding rate similar to that of copper and can also be used for EV/HEV automotive cables and other applications in the future.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.59-65
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• 2019

The EMI shielding effectiveness of shielding layers thickness was analyzed when the low conductivity shielding layers was placed in the near field of the noise source. A spiral antenna with broadband characteristics was used as the noise source, and graphite was selected as the low conductivity shielding material. Two spiral antennas were constructed to analyze the transmission coefficient between two antennas, and the distances between the transmitting and receiving antennas were 5 cm and 10 cm. The thickness of the shielding layers was changed from 1 um to 200 um. The frequency was changed from 100 MHz to 6 GHz to obtain a maximum SE(Shielding Effectiveness) of 70 dB. In this simulation, electronic shielding was used due to the nature of graphite, which is a shielding film material. Based on these results, we will study how to improve the shielding performance by implementing magnetic shielding in the future.

• Journal of Hydrogen and New Energy
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• v.30 no.6
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• pp.540-548
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• 2019

This study was conducted to develop insulation for solid oxide fuel cell (SOFC). The developed insulation is based on the lamination technology and the radiation shielding technology of the satellite insulation. The insulation material is consisting of insulation material for conduction resistance, spacer, and radiation shielding material. The experimental apparatus consisting vacuum bell jar, pump, heater and temperature recording device has developed to verify the performance of the insulation. The experimental values were used as reference data for the modeling development. In this paper, heat transfer is assumed to be one- dimensional phenomena for the prediction of insulation performance and internal temperature distribution in high temperature region of SOFC. The developed model was used to compare the performance difference of insulation types according to composition materials. The analysis result shows that the insulation including spacer and radiation shielding has better heat insulation performance than other cases. In this study, the thickness reduction effect of about 20% was shown compared to the insulation including only conductive material. It is noted that the radiant shielding material should be carefully selected for durability, because SOFC insulation should be used for a long time at high temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.114-115
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• 2018

To develop an effective shielding material for spent fuel that emits fast neutrons is necessary. In this study, thermal neutron and fast neutron shielding performance of polyethylene coated boron carbide-incorporated cement paste was quantitatively analyzed by Monte Carlo N-Particle transport code (MCNP) simulations. As the results of the simulations, fast neutrons were effectively shielded through large quantity of hydrogen and boron elements in polyethylene and boron carbide.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.641-649
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• 2023

This study compares and analyzes the performance of a shield manufactured using 3D printing technology to find out its applicability as a shield in high-energy electron beam therapy. Actual measurement and monte carlo simulations were performed to evaluate the shielding performance of 3D printing materials for high-energy electron beams. First, in order to secure reliability for the simulation, a source term evaluation was conducted by referring to the IAEA's TRS-398 recommendation. Second, to analyze the shielding performance of PLA+W (93%), a specimen was manufactured using a 3D printer, and the shielding rate by thickness according to electron beam energy was evaluated. Third, the shielding thickness required for electron beam treatment was calculated through a comparative analysis of shielding performance between PLA+W (93%) and existing shielding bodies. First, as a result of the evaluation of the source term through actual measurement and simulation, the TRS-398 recommendation was satisfied with an error of less than 1%, thereby securing the reliability of the simulation. Second, as a result of the shielding performance analysis for PLA+W (93%), 6 MeV electron beams showed a shielding rate of more than 95% at 3.12 mm, and 15 MeV electron beams showed a shielding rate of more than 90% at 10 mm thickness. Third, through simulations, comparative analysis between PLA+W (93%) materials and existing shields showed high shielding rates within the same thickness in the order of tungsten, lead, copper, PLA+W (93%), and aluminum. 6 MeV electron beams showed almost similar shielding rates at 5 mm or more and 15 MeV electron beams. Through this study in the future, it is judged that it can be used as basic data for the production and application of shielding bodies using PLA+W (93%) materials in high-energy electron beam treatment.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.3307-3314
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• 2024

For traditional spent fuel shielding materials, due to physical and chemical defects and cost constraints, they have been unable to meet the needs. Therefore, this paper carries out the first discussion on the application and performance of bismuth in neutron shielding by establishing Monte Carlo simulation on the neutron flux model of shielded spent fuel. Firstly, functional fillers such as bismuth oxide, lead oxide, boron oxide, gadolinium oxide and tungsten oxide are added to the matrices to compare the shielding rates of aluminum alloy matrix and silicone rubber matrix. The shielding rate of silicone rubber mixture is higher than aluminum alloy mixture, reaching more than 56%. The optimal addition proportion of bismuth oxide and lead oxide is 30%, and the neutron radiation protection efficiency reaches 60%. Then, the mass attenuation coefficients of bismuth oxide, lead oxide, boron oxide, gadolinium oxide and tungsten oxide in silicone rubber matrix are simulated with the change of functional fillers proportion and neutron energy. This simulation result shows that the mixture with functional fillers has good shielding performance for low energy neutrons, but poor shielding effect for high energy neutrons. Finally, in order to further evaluate the possibility of replacing lead oxide with bismuth oxide as shielding material, the half-value layers and various properties of bismuth oxide and lead oxide are compared. The results show that the shielding properties of bismuth oxide and lead oxide are basically the same, and the mechanical properties, heat resistance, radiation resistance and environmental protection of bismuth oxide are better than that of lead oxide. Therefore, in the case of neutron source strengths in the range of 0.01-6 MeV and secondary gamma rays produced below 2.5 MeV, bismuth can replace lead in neutron shielding applications.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.1
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• pp.21-29
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• 2021

Recently, semiconductor chips and electronic components are increasingly being used in IT devices such as wearable watches, autonomous vehicles, and smart phones. As a result, there is a growing concern about device malfunctions that may occur due to electromagnetic interference being entangled with each other. In particular, electromagnetic wave emissions from wearable or flexible smart devices have detrimental effects on human health. Therefore, flexible and transparent electromagnetic interference (EMI) shielding materials and films with high optical transmittance and outstanding shielding effectiveness have been gaining more attention. The EMI shielding films for flexible and transparent electronic devices must exhibit high shielding effectiveness, high optical transmittance, high flexibility, ultrathin and excellent durability. Meanwhile, in order to prepare this EMI shielding films, many materials have been developed, and results regarding excellent EMI shielding performance of a new materials such as carbon nano tube (CNT), graphene, Ag nano wire and MXene have recently been reported. Thus, in this paper, we review the latest research results to EMI shielding films for flexible and transparent device using the new materials.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.310-316
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• 2020

In this study, the stability and EMP shielding performance of metal-based industrial by-products aggregates with excellent conductivity and easy procurement to be used as concrete aggregates for EMP shielding are evaluated. The industrial by-products are electronic-arc-furnace oxidizing slag, copper smelting slag, and ferro-moldibdenum. The composition analysis of aggregates and aggregate stability are evaluated. As a result of the experiment, ferro-moldibdenum is shown to have l ow stability as an aggregate due to its high Free-CaO. The remaining aggregates are evaluated to be safe to use as aggregates for concrete. In addition, industrial by-products aggreagate-specimens excluding ferro-moldibdenum are shown higher compressive strength than the plain specimen. The recycle aggregates, electronic-arc-furnace oxidizing slag and copper smelting slag, are shown excellent EMP shielding performance, the EMP shielding performance is expected to increase if the average particle diameter of the aggregate is small or evenly distributed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.107-112
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• 2018

Shielding effectiveness (SE) improvement with EMI shield layers fabricated by conformal spray coating system was studied. Silver or Nickel powder filled acrylic resin were sprayed on the samples. We compared the performance with the viscosity of 400 cPs and 100 cPs cases. The thickness range of the coating layer was 20 to 50 um for the silver, 60 to 120 um for the nickel. The shielding effectiveness was measured by ASTM D4935 using coaxial type TEM-cell. The silver-filled resin showed much better performance than that of the nickel-filled resin. The shielding effectiveness increased almost proportional to the thickness of the coating layers until being saturated around 63 dB for the silver-layer or around 34 dB for the nickel-layer. The best performance measured in this study was the shielding effectiveness of 63 dB with $35{\mu}m-thick$ of silver-layer.

• Journal of the Korea Institute of Building Construction
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• v.21 no.6
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• pp.519-527
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• 2021

In this study, an electromagnetic pulse shielding effect was obtained by applying the arc metal spraying method to the ordinary concrete. For this study, to evaluate the electrical properties in the thickness of the metal sprayed coating, 8 types of metals(Cu, CuAl, CuNi, CuZn, Al, Zn, ZnAl, AlMg) were sprayed as coatings with a thickness of 100, 200 and 500㎛. The electrical conductivity on the surface was measured with a 4-pin probe, and an electromagnetic wave shielding effect test was performed according to KS. Based on the test results, 200 ㎛ was proposed as an optimal metal coating thickness for electromagnetic pulse shielding, and it was thermally sprayed on a 300×300×100mm concrete specimen to analyze the electromagnetic wave shielding performance. However, in the area of adhesion strength, the maximum was 1.11MPa, which was found to be less than 74% of the target performance.