• Journal of Ceramic Processing Research
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• v.23 no.2
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• pp.165-170
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• 2022

Using electromagnetic shielding technology, the exterior walls of buildings can prevent the penetration of electromagnetic waves. This effectively reduces the electromagnetic field intensity and electromagnetic pulse inside buildings. Therefore, in recent years, researchers have focused on developing electromagnetic shielding technology. In this study, we analyzed the physical properties and EMP shielding efficiency of shielding materials, such as silicon carbide (SiC), obtained as a byproduct of the semiconductor manufacturing processes, and graphite mixed with mortar, used in the external walls. The shielding materials underwent pretreatment, such as grinding, before mixing them with mortar. Because shielding materials are expensive, the shielding efficiency was calculated by mixing the respective shielding materials with mortar in only the outermost 10% of the sample mortar volume. Moreover, we calculated the shielding efficiency of the different samples of mortar with shielding materials throughout the volume of the samples using shielding effectiveness (SE) estimation formula. The predicted SE values of the samples of mortar mixed with granular SiC, graphite powder, and SiC powder were 20 dB, 18 dB, and 28 dB, respectively. The SE of the sample of mortar mixed with SiC powder is approximately equal to 30 dB, that is, the maximum shielding efficiency (99.9%).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.221-225
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• 2014

In modern times, threat of high power electromagnetic wave is increasing. When the electrical grid and communication network are attacked by these high power electromagnetic wave, the whole infrastructure is paralyzed. To protect the infrastructure from these high power electromagnetic wave threat, the shielding facility that can block high power electromagnetic wave is constructed. Also shielding effectiveness evaluation about the constructed facility is important. But, because of space efficiency and saving of construction cost to construct the actual shielding facility, the shielding room wall is generally adjacent to exterior concrete structures. As space between shielding facility wall and concrete structures is very small, arranging the transmitting antenna exterior shielding facility is realistically difficult. Therefore, in this research, The shielding effectiveness measurement plan in the state of exterior narrow space of HEMP shielding facility is presented. And to apply this plan, The influence of shielding effectiveness according to the size of the shielding facility is analyzed.

• Proceedings of the IEEK Conference
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• 2009.05a
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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.

• Journal of the Korea Convergence Society
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• v.4 no.4
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• pp.49-57
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• 2013

The lightning shielding of different 500 kV HVAC-TL high voltage AC transmission lines was analyzed. The studied transmission lines were horizontal flat single circuit and double circuit transmission lines. The lightning attractive areas were drawn around power conductors and shielding wires. To draw the attractive areas of the high voltage transmission lines, transmission line power conductors, shielding wires and lightning leader were modeled. Different parameters were considered such as lightningslope, ground slope and wind on lightning attractive areas. From the calculated results, the power conductors voltages affected on attractive areas around power conductors and shielding wires. For negative lightning leader, the attractive area around the transmission line power conductor increased around power conductors stressed by positives voltage and decreased around power conductors stressed by negative voltage. In spite of this, the attractivearea of the transmission line shielding wire increasedaround the shielding wire above the power conductor stressed by the positive voltage and decreased around the shielding wire above the power conductor stressed by negative voltage. The attractive areas around power conductors and shielding wires were affected by the surrounding conditions, such as lightning leader slope, ground slope. The AC voltage of the transmission lines made the shielding areas changing with time.

• Journal of radiological science and technology
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• v.43 no.5
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• pp.383-388
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• 2020

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.

• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.87-94
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• 2021

While the shielding substances of radiation shields in medical institutions are beginning to be replaced by environmentally friendly materials, radiation protection according to the shielding properties of environmentally friendly substances is becoming an important factor rather than the existing lead shielding properties. Tungsten and barium sulfate are representative shielding materials similar to lead, and are made in sheets or fiber form with eco-friendly materials. Ytterbium is an impermeable material used as a fluorine compound in the dental radiation field. This study aims to evaluate the shielding performance in the x-ray shielding area by comparing the shielding properties of ytterbium by energy band and that of existing eco-friendly materials. When three types of shielding sheets were fabricated and tested under the same process conditions, the shielding performance of the medical radiation area was about 5 % difference from tungsten. Furthermore, shielding performance was superior to barium sulfate. In the cross-sectional structure of the shielding sheet, there was a disadvantage that the arrangement of particles was not uniform. Ytterbium oxide showed sufficient potential as a medical radiation shielding material, and it is thought that it can improve the shielding performance by controlling the particle arrangement structure and particle size.

• Proceedings of the KSME Conference
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• 2001.11a
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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.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.20-21
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• 2016

In this study, the shielding properties of concrete with conductive materials as shielding material for electromagne- tic pulse(EMP) within 10kHz~18GHz were investigated. The shielding effectiveness of specimens were compared with different entrained materials. The shielding effectiveness were determined according to MIL-STD-188-125-1, IEEE-STD-299 at 28 days of concrete curing. The results of shielding effectiveness did not meet the criteria(80dB) severely.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.244-249
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• 2004

In this paper, shielding effectiveness(SE) of the shielding paint of electromagnetic(EM) waves was investigated with actual experiments. The shielding paint used in this study were made of powder of conductive materials - Ag, Cu, Al, Sn, Ni. Cr, Graphite and Charcoal etc. with a solubility in oil and water. Also, the paper was used as a base sheet. 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, nickel 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 about the EM shielding paint. The SE strongly depended on the electric resistance by density of painting particles. SE increased as the density of particles was increasing.

• Corrosion Science and Technology
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• v.9 no.4
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• pp.153-158
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• 2010

Electrical appliances such as audiovisual equipment and personal computers have recently had heat and electromagnetic problems. In order to solve those problems, 'High heat absorbing pre-painted steel sheet (hereinafter referred to as PSS)', 'High electromagnetic shielding PSS' and 'High heat absorbing and high electromagnetic shielding PSS' have been developed. In this paper, the heat characteristics and electromagnetic shielding properties of PSS are investigated by methods that use enclosures and their mechanisms are discussed. It was found that 'High heat absorbing PSS' and 'High heat absorbing and high electromagnetic shielding PSS'could reduce the heat problem. The mechanism of the heat characteristics was presumed for the high heat absorptivity of the back coating inside the enclosure. And it was also found that 'High electromagnetic shielding PSS' and 'High heat absorbing and high electromagnetic shielding PSS' could shield electromagnetic waves well. The mechanism of the electromagnetic shielding properties was considered for the low transfer impedance of the back coating inside the enclosure. 'High heat absorbing PSS' and 'High electromagnetic shielding PSS' have been adopted as materials for electrical appliances and 'High electromagnetic shielding and high heat absorbing PSS' have been tested for that purpose.