• Macromolecular Research
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• v.10 no.5
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• pp.253-258
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• 2002

The multi-wall carbon nanotubes (MWNTs) with graphite crystal structure were synthesized by the catalytic decomposition of a ferrocene-xylene mixture in a quartz tube reactor to use as the conductive filler in the binary polymer matrix composed of poly(vinylidene fluoride) (PVdF) and poly(vinyl pyrrolidone) (PVP) for the EMI (electromagnetic interference) shielding applications. The yield of MWNTS was significantly dependent on the reaction temperature and the mole ratio of ferrocene to xylene, approaching to the maximum at 800 $^{\circ}C$ and 0.065 mole ratio. The electrical conductivity of the MWNTs-filled PVdF/PVP composite proportionally depended on the mass ratio of MWNTs to the binary polymer matrix, enhancing significantly from 0.56 to 26.7 S/cm with the raise of the mass ratio of MWNTs from 0.1 to 0.4. Based on the higher electrical conductivity and better EMI shielding effectiveness than the carbon nanofibers (CNFs)-filled coating materials, the MWNTs-filled binary polymer matrix showed a prospective possibility to apply to the EMI shielding materials. Moreover, the good adhesive strength confirmed that the binary polymer matrix could be used for improving the plastic properties of the EMI shielding materials.

• Journal of Aerospace System Engineering
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• v.4 no.3
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• pp.24-28
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• 2010

The purpose of this study is to define available microwave absorbing structure for aircraft from in the X-band(8.2~12.4GHz) frequencies. The electromagnetic wave absorption or shielding techniques is an important issue not only for military purpose but also for commercial purposes. Aircraft Radar Absorbing Structure(RAS) is absorbed or scattered propagation waves from the enemy radar. There are absorbing technologies at shaping design techniques and using Radar Absorbing Materials(RAM). RAM is more important because shaping design can't include perfect radar absorbing performance. In this study, based on material properties was introduced RAM and to analyze the each characteristics. Finally, we comparison appropriate RAM for aircraft.

• Journal of the Korea Institute of Building Construction
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• v.19 no.6
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• pp.477-484
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• 2019

The purpose of this study is to present basic data for developing concrete with EMP shielding as the structure materials when constructing an EMP shielded building structure. In order to use metal-based recycled aggregates with excellent conductivity and easy procurement for EMP shielding concrete, an evaluation of the stability evaluation and EMP shielding performance was performed. Through the stability evaluation, it was found that the coarse aggregate stability criterion was satisfied, but the oxidized slag did not satisfy the fine aggregate stability criterion, the oxidized slag is not satisfied. In addition, as a result of fresh concrete, the workability is increased and the air volume is decreased. The compressive strength is increased due to the high density and coarse granularity of the recycled aggregates, which increased the cement paste and adhesion, thereby increasing the compressive strength. The results of an EMP shielding test show that aggregates with high shielding performance are electronic arc furnace(EAF) Oxidizing Slag and Cooper Slag. The shielding performance is expected to increase if the average particle size of aggregate is small or uniformly distributed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.785-787
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• 2002

Conductivity and transmittancy of ZnO is very excellent and the price is low. So the study of transparent electrode materials and electromagnetic wave shielding wall is actively in progress. We add $Al_2O_3$(0.0, 2.0, 3.0, 5.0wt%) to ZnO and observe microscopic structure and conductivity. For XRD observation, Al peak of AZO is increased by increasing the amount of $Al_2O_3$. We observe that the size of grain is reduced by increasing the liquid phase of grain boundary to SEM observation. Conductivity of AZO is increased by increasing the amount of $Al_2O_3$. We confirm the application possibility of the materials for electromagnetic wave reflection materials.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1843-1846
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• 1997

This paper describes the fault reducing effects of the 154 kV transmission tower by auxiliary grounding from the top of the tower to ground. The grounding surge impedance of the auxiliary grounding system is calculated by CDEGS(:Current Distribution Electromagnetic Interference Grounding and Soil Structure Analysis), and the critical lightning back flashover current and arcing horn dynamic characteristics are simulated by EMTP/TACS(:Electromagnetic Transient Program/Transient Analysis of Control Systems). The calculated results of total LFOR(Lightning Flashover Rate) shows that the LFOR can be reduced from 5.2(count/100km. year) to 3.4 by auxiliary grounding on the 154 kV transmission tower with one ground wire shielding system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.76-79
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• 2017

This paper presents the electromagnetic shielding structure for low frequency wireless power transfer system with magnetic induction method using soft magnetic materials. Soft magnetic materials have advantages such as high permeability and low magnetic loss, but have undesirable effect of power loss by eddy current. To overcome this, we proposed the patterned soft magnetic material to suppress the eddy current path. For validity of this paper, we simulated the coil transfer efficiency and the radiated electromagnetic field, and fabricated the proposed structure using 79-permalloy. The measured results shows good agreements with the simulated results and reduction of the radiated electromagnetic field compared to commercial ferrite plate.

• Transactions on Electrical and Electronic Materials
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• v.14 no.6
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• pp.295-298
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• 2013

Nano-size manganese ferrite reinforced conductive polypyrrole composites reveal a core-shell structure by in situ polymerization, in the presence of dodecyl benzene sulfonic acid as the surfactant and dopant, and iron chloride as the oxidant. The structure and magnetic properties of manganese ferrite nano-fillers were measured, by using X-ray diffraction and vibrating sample magnetometer. The morphology, microstructure, and conductivity of the composite were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, and four-wire technique. The microwave-absorbing properties of composites reinforcement dispersed in resin coating with the coating thickness of 1.2 nm were investigated, by using vector network analyzers, in the frequency range of 8~12 GHz. A reflection loss of -8 dB was observed at 10.5 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1384-1393
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• 2008

In this paper, we analyzed the multilayer structure with lossy metamaterials using ABCD Matrix method to get the transmission characteristics. Compared to the recursive method which cannot be used to analyze the lossy characteristics of multilayer structure because of its complexity, we used the ABCD matrix method is easy to apply because of its matrix chain concepts for arbitrary number of multilayer structure and lossy material. To verify the results of this paper, we used both for multilayer dielectric and metamaterial, respectively, and obtained the same results. Multilayer structure with lossy metamaterial showed minimized ripple and broadband transmission compared to dielectric multilayered structure. This can be used in various applications as antenna radome and shielding material, etc.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.735-741
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• 2016

Increasing the total length of waveguide-below-cutoff array(WBCA) as it is used to the duct in order to enhance shielding effectiveness, the design could cause higher cost, higher levels of difficulties in construction and the interruption a flow velocity. The multi-layered WBCA can compensate for this problem, which can be designed by crossing each waveguide layer. By conducting simulations from 2-layer to 8-layer structure, it can be observed that the shielding effectiveness increases from 52 dB to 75 dB. Comparing with the original WBCA in a shape of mono layer rectangular, our proposed waveguide becomes similar with the original value as the number of crossing layer increases. In addition, the analysis with the flow of fluid in the duct installed multi-layered WBCA are required. We demonstrate this analysis by doing the flow of fluid simulation, and concluded that the multi-layered WBCA has loss of flow of fluid less than unit rectangular WBCA.

• Carbon letters
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• v.9 no.2
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• pp.115-120
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• 2008

Rubber reinforcing carbon black N330 was treated by physical activation under $CO_2$ to different degrees of burn-off. The mechanical properties indicating the reinforcement of SBR (Styrene-Butadiene Rubber) vulcanizates filled by activated carbon blacks, such as tensile strength, modulus at 300% strain and elongation at break were determined. During $CO_2$ activation of fresh carbon blacks, the development of microporous structure caused an increase of extremely large specific surface area and the porosity turned out to be an increasing function of the degree of burn-off. The tensile strength and modulus at 300% of activated carbon blacks filled rubber composites were improved at lower loading ratios of 20 and 30 phr, but decreased drastically after 30 phr, which is considered that it might be difficult to get a fully dispersed rubber mixture at higher loading ratios for fillers having very large specific surface areas. However, the Electromagnetic Interference (EMI) shielding effectiveness of SBR rubber composites having activated carbon black at 74% yield were improved at a large extent when compared to those having raw carbon black and increased significantly as a function of increasing loading ratio.