• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.90-97
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• 2018

The quantities of electronic waste have been increased rapidly, and was caused variety problems such as environmental pollution or dissipation of resource. So, it needed to development of recycling technology about heavy metal in the electronic waste. Meanwhile, filler material (concrete or mortar) was used for shielding radioactive waste, however, it did not used materials that it is proved radiation shielding performance. So, there is a lack of confidence in the shielding performance. Therefore, in this paper, mechanical properties of concrete was evaluated for the applicability using electronic waste as fine aggregate of filler material. From the test results, compressive and flexural strength and elasticity modulus and the micro pore in the $1{\mu}m$ range was significantly affected by substitution of electronic waste, however, it could be improved the performance by using mineral admixture as binder. So, it is shown that the electronic waste could be applicable as fine aggregate of filler material.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.7
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• pp.639-647
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• 2009

In this work, wrapping conductors with thin magnetic materials is proposed as a magnetic shielding method. The 0.1 mm thick metal sheets of mu-metal, grain-oriented electrical steel, and non-oriented electrical steel were produced from commercial alloy sheets through cold rolling and followed high temperature annealing. In case of 3-phase electric currents, mu-metal was the best in shielding performance at a B-field magnitude of about 100 ${\mu}T$, whereas silicon steels were better than mu-metal at a B-magnitude over 500 ${\mu}T$. In addition, wrapping with silicon steel(inner) together with mu-metal(outer) resulted in a shielding factor less than 0.1 even at 500 ${\mu}T$. These results are due to changes in hierarchy of magnetic permeabilities of the materials with increasing magnetic field strength. In case of single-phase electric current, B-magnitude outside the magnetic shell was rather increased compared to the unshielded case. This result is explained by vector composition of B-fields near magnetic shielding materials.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.111-118
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• 2023

MXene, a two-dimensional transition metal carbide or nitride, has recently attracted much attention as a lightweight and flexible electromagnetic shielding material due to its high electrical conductivity, good mechanical strength and thermal stability. In particular, the Ti-based MXene, Ti₃C₂T_x and Ti₂CT_x are reported to have the best electrical conductivity and electromagnetic shielding properties in the vast MXene family. Therefore, in this study, Ti₃C₂T_x and Ti₂CT_x films were prepared by vacuum filtration using Ti₃C₂T_x and Ti₂CT_x dispersions synthesized by interlayer metal etching and centrifugation of Ti₃AlC₂ and Ti₂AlC. The electrical conductivity and electromagnetic shielding efficiency of the films were measured after heat treatment at high temperature. Then, X-ray diffraction and photoelectron spectroscopy were performed to analyze the structural changes of Ti₃C₂T_x and Ti₂CT_x films after heat treatment and their effects on electromagnetic shielding. Based on the results of this study, we propose an optimal structure for an ultra-thin, lightweight, and high performance MXene-based electromagnetic shielding film for future applications in small and wearable electronics.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.5
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• pp.190-194
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• 2002

The aim of development is system having convenient, cheap, reliable and better good measurements. The cozy environments in auto and architects is essentiable requirements. This study focuses on system developments of test equipment for better performance of noise protection in automobiles. Sound cards using makes easily to acquire the sound in each room, especially reduced the complexities of the circuits. The developed system have easily been measured and have characteristics of rapid mecanical response. The menu of rough scan method makes efficiently to test the shielding performance of auto rubber in whole frequency scales.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.197-204
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• 2016

Concrete walls of neutron generating facilities such as fusion reactors and fission reactors become radioactive by neutron irradiation. Both low-activation and neutron shielding are a critical concern at the dismantling stage after the shutdown of facilities with a requirement of radioactive waste management. To tackle this, two types of additives were investigated in fabricating mortar specimens: synthetic high polymers and boron carbide. It is well known that a hydrogen atom is effective in neutron shielding by an elastic scattering because its mass is almost the same as that of the neutron. And boron is an effective neutron absorber with a big neutron absorption cross section. In this study, the effect of the type, shape, and size of polymers were investigated as well as that of boron carbide. Total 16 mix designs were prepared to reveal the effect of polymers on mechanical properties and neutron shielding performance. The neutron does equivalent of polymers-based mortar for fast neutrons decreased by 36 %, and the count rate of boron carbide-based mortar with regard to thermal neutrons decreased by 90 % compared to conventional mortar. These results showed that a combination of polymers and boron carbide compounds has potential to reduce the thickness of neutron shields as well as radioactive waste from reactors.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.163-170
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• 2019

In recent years, various types of industrial wastes are rapidly increasing with the development of high-tech industries. Specially, high-density waste glass of CRT TV containing heavy metals are buried or disposed of due to reprocessing costs and environmental pollution problems. Thus, more basic research is needed to recycle waste such as CRT waste glass such. In this study, the fundamental properties and radiation shielding performance of mortar specimens substituted CRT waste glass as a fine aggregate were analyzed and their application to shielding materials was evaluated. According to the results, the bulk density of mortar specimen replaced with CRT waste glass was increased and the compressive strength and flexural strength were decreased. Meanwhile, the CRT waste glass substitute specimen containing a large amount of lead component showed a higher shielding performance than the general mortar specimen. Especially, the linear attenuation coefficient of CRT waste glass in $122KeV{\cdot}^{57}Co$ of the low energy field was 2.5 times higher than that of normal specimen.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.172-180
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• 2019

In this study, the microstructure and gamma-ray shielding efficiency of CRT glass mortar specimen were evaluated with replacement ratio and material properties. The results show that as the replacement ratio of CRT waste glass increases, the volume of pores with diameters below 50 nm and above 400 nm is increased. Also, the half-value layer of CRT glass mortar decreased with the increasing of linear attenuation coefficient. In addition, compressive and flexural strength were reduced when CRT waste glass was replaced as the fine aggregate, but the mechanical performance of CRT mortar specimen could be obtained by substitution of the mineral admixture.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1464-1470
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• 2022

This paper presents a high performance burnable absorber named as CIMBA (Cylindrically Inserted and Mechanically Separated Burnable Absorber) for the soluble-boron-free SMR. The CIMBA is the cylindrical gadolinia inserted into the annular fuel pellets. Although the CIMBA utilizes the spatial self-shielding effect of the fuel material, a large reactivity upswing occurs when the gadolinia is depleted. To minimize the reactivity swing of the CIMBA-loaded FA, two approaches were investigated. One is controlling the spatial self-shielding effect of the CIMBA as burnup proceeds by a multi-layered structure of the CIMBA (ML-CIMBA) and the other is the mixed-loading of two different types of CIMBA (MIX-CIMBA). Both approaches show promising performances to minimize the reactivity swing, where the MIX-CIMBA is more preferable due to its simpler fabrication process. In conclusion, the MIX-CIMBA is expected to accelerate the commercialization of the CIMBA and can be used to achieve an optimal soluble-boron-free SMR core design.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.18-23
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• 2022

This paper examines the electromagnetic shielding structure of ultra-high frequency (UHF) RF modules used in aircraft. Advances in electrical and electronic technologies have increased the need for electronic equipment in aircraft. High-frequency wireless devices have become integrated circuits in the form of UHF integrated circuits to support a wide range of frequencies and miniaturisation. To ensure the functionality and performance of these integrated devices in aviation, shielding is necessary to prevent unexpected electromagnetic interference, which could be detrimental to aircraft safety. A shield structure was designed to protect the RF chipset from malfunctioning, and the shielding effectiveness was improved through the application of various geometric shapes.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1565-1570
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• 2020

Photons with the energy of 60 keV are regularly used for some kinds of bone density examination devices, like the single photon absorptiometry (SPA). This article reports a flexible and lightweight rare earth/polymer composite for enhancing shielding efficiency against photon radiation with the energy of 60 keV. Lead oxide (PbO) and several rare earth element oxides (La₂O₃, Ce₂O₃, Nd₂O₃) were dispersed into natural rubber (NR) and the photon radiation shielding performance of the composites were assessed using monte carlo simulation method. For 60 keV photons, the shielding efficiency of rare earthbased composites were found to be much higher than that of the traditional lead-based composite, which has bad absorbing ability for photons with energies between 40 keV and 88 keV. In comparison with the lead oxide based composite, Nd₂O₃-NR composite with the same protection standard (the lead equivalent is 0.25 mmPb, 0.35 mmPb and 0.5 mmPb, respectively), can reduce the thickness by 35.29%, 37.5% and 38.24%, and reduce the weight by 38.91%, 40.99% and 41.69%, respectively. Thus, a flexible, lightweight and lead-free rare earth/NR composite could be designed, offering efficient photon radiation protection for the users of the single photon absorptiometry (SPA) with certain energy of 60 keV.