• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.9
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• pp.950-954
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• 2003

This paper presents the delivered power and reflection coefficient in metallic shielding enclosure excited by the interior source, which are evaluated with the method of moments, and describes a method for reducing the radiation of electromagnetic fields in the cavity by putting lossy dielectric material in one inside wall. In this paper we introduce carbon polystyrene-foam as lossy dielectric material and observe it's effects of reduction when the thickness and permittivity of lossy dielectric material are changed. The results show that the reduction of the electromagnetic radiation can be achieved by controlling the amount of carbon in lossy dielectric material. The theoretical analysis is verified by the measured delivered power.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.7
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• pp.843-850
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• 2003

Cu/PET film composites were prepared by electroless copper plating method. In order to improve adhesion between electroless plated Cu layer and polyester (PET) film, the effect of pretreatment conditions such as etching method, mixed catalyst composition were investigated. Chemical etching and plasma treatment increased surface roughness in decreasing order of Ar＞HCl＞O$_2$＞NH$_3$. However, adhesion of Cu layer on PET film increased in the following order: $O_2$＜Ar＜HCl＜NH$_3$. It indicated that appropriate surface roughness and introduction of affinitive functional group with Pd were key factors of improving adhesion of Cu layer. PET film was more finely etched by HCI tolution, resulting in an improvement in adhesion between Cu layer and PET film. Plasma treatment with NH$_3$produced nitrogen atoms on PET film, which enhances chemisorption of Pd$^{2+}$ on PET film, resulting in improved adhesion and shielding effectiveness of Cu layer deposited on the Pd catalyzed surface. Surface morphology of Cu plated PET film revealed that Pd/Sn colloidal particles became more evenly distributed in the smaller size by increasing the molar ratio of PdCl$_2$; SnCl$_2$from 1 : 4 to 1 : 16. With increasing the molar ratio of mixed catalyst, adhesion and shielding effectiveness of Cu plated PET film were increased.d.

• Journal of the Korean Ceramic Society
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• v.37 no.4
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• pp.345-353
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• 2000

Carbon nanofibers were prepared from the decomposition of various carbon-containing gases over pure Ni, pure Fe and their alloys with Cu. They yields, properties, and structure of carbon nanofibers obtained from the various reaction conditions were analyzed. Type of reacting gas, reaction temperature and catalyst composition were changed as the reaction variable. With Ni-Cu catalysts, the maximum yields of carbon nanofibers were obtained at temperatures between 550 and 650$^{\circ}C$ according to the reacting gas mixtures of C2H2-H2, C2H4-H2 and C3H8-H2, and the surface areas of the carbon nanofibers produced were 20∼350㎡/g. In the case of CO-H2 mixture, the rapid deposition of carbon nanofibers occurred with Fe-Cu catalyst and the maximum yield were obtained around 550$^{\circ}C$ with the range of surface areas of 140∼170㎡/g. The electrical resistivity of carbon nanofiber regarded as the key property of filler for the application of electromagnetic interference shielding was very sensitive to the type of reactant gas and the catalyst composition ranging 0.07∼1.5Ωcm at a pressure of 10000 psi, and the resistivity of carbon nanofibers produced over pure nickel catalyst were lower than those over alloy catalysts. SEM observation showed that the carbon nanofibers produced had the diameters ranging 20∼300 nm and the straight structure of carbon nanofibers changed into the twisted or helical conformation by the variation of reacting gas and catalyst composition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.7
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• pp.554-559
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• 2010

In this paper, we analyzed the frequency spectrum of radiated electromagnetic pulses generated by series arc- and corona- discharges as a basic study to develop an on-line diagnostic technique for power facilities installed inside closed-switchboards. To simulate series arc and corona discharges, five types of electrode system which consists of needle and plane electrodes were arranged. The experiment was carried out in an electromagnetic shielding room, and the measurement system consists of an ultra log antenna and an EMI receiver. From the experimental results, the frequency spectrum exists in ranges from 30 MHz to 2 GHz for a series arc discharge and 30 MHz to 1.2 GHz depending on defects for a corona discharge. The peak frequency of the series arc- and corona- discharges were 100 MHz to 160 MHz and 40 MHz to 80 MHz, respectively.

• Macromolecular Research
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• v.17 no.11
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• pp.863-869
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• 2009

The effect of a multiwalled carbon nanotube (MWCNT) dispersion on the electrical, morphological and rheological properties of polycarbonate (PC)/MWCNT composites was investigated, with and without pretreating the MWCNTs with hydrogen peroxide oxidation and lyophilization. The resulting PC/treated MWCNT composites showed higher electrical conductivity than the PC/untreated MWCNT composites. The morphological behavior indicated the treated composites to have greater dispersion of MWCNTs in the PC matrix. In addition, the electromagnetic interference shielding efficiency (EMI SE) of the treated composites was higher than that of the untreated ones. Rheological studies of the composites showed that the complex viscosity of the treated composites was higher than the untreated ones due to increased dispersion of the MWCNTs in the PC matrix, which is consistent with the electrical conductivity, EMI SE and morphological studies of the treated composites. The latter results suggested that the increased electrical conductivity and EMI SE of the treated composites were mainly due to the increased dispersion of MWCNTs in the PC matrix.

• Journal of Adhesion and Interface
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• v.18 no.2
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• pp.59-67
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• 2017

Recently, integration of parts is accelerating according to the growth of the smart mobile industry. The integration of these parts causes problems of interference phenomena between the parts, and the importance of electromagnetic wave shielding technology to solve this problem is highlighted. Electromagnetic wave shielding technology is implemented so as to reflect or absorb electromagnetic waves, and generally conductive materials are utilized for electromagnetic wave shielding. Transparent shielding technology is required according to recent industrial changes. In this research, we propose transparent the shielding film using imprint technology with conductive composite binder. Utilizing UV polymerized acrylic binder to produce a conductive composite binder. Spherical, plate and stacked silver particles were used for conductivity. The changes of the curing characteristics, conductivity and adhesion were observed according to the structural characteristics of the silver particles. The use of spherical particles was the most efficient in the curing process, and an additional curing system was required to complement the UV-shadowing structure. In the conductivity evaluation, the stacked structure showed excellent characteristics. The adhesion of spherical system was the best. It is evaluated as a result of irregularities on the surface. Ultimately, the patterned film using this showed excellent transparency characteristics.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.351-358
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• 2018

In this study, we propose a method of suppressing the leakage noise signal of motor assembly through the test. The motor assembly is mounted on outside of the aircraft to rotate an antenna and must satisfy RE102 requirement on MIL-STD-461F in terms of electromagnetic interference. It is confirmed by RE102 test result hat the leakage noise signal of the equipment occurs due to external influx through the power and control cable and rotation of the motor. And it is ascertained that the part where internal/external physical shielding is difficult to rotate is the leakage path. To reduce the leakage noise signal, the electrical ground reinforcement and the electric shielding structure considering the operation of the equipment is applied and it is verified that the requirement is satisfied. Finally, we verified that required specification are met by applying circular corrugated choke with interlocking shapes and conductive grease to the noise leakage path.

• Polymer(Korea)
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• v.25 no.2
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• pp.302-310
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• 2001

Cu/PET film composites were prepared by electroless copper plating method. In order to improve adhesion between electroless Cu plated layer and polyester (PET) film, the effect of pretreatment conditions such as etching method and mixed catalyst composition, and accelerator was investigated. Compared to NaOH etching medium, PET film was more finely etched by HCl solution, resulting in an improvement in adhesion between Cu layer and PET film. However, there were no significant differences in electromagnetic interference shielding effectiveness as a function of etching medium. The surface morphology of Cu plated PET film revealed that Pd/Sn colloidal particles became more evenly distributed in the smaller size by increasing the molar ratio of PdCl$_2$ : SnCl$_2$ from 1 : 4 to 1 : 16. With increasing the molar ratio of mixed catalyst, the adhesion and the shielding effectiveness of Cu plated PET film were increased. Furthermore, HCl was turned out to be a better accelerator than NaOH in order to enhance the activity of the mixed PdCl$_2$/SnCl$_2$ catalyst, which facilitated the formation of more uniform copper deposit on the PET film.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.57-60
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• 2008

Magnesium alloys usage has been increased every year owing to its lightness, damping capacity, and EMI shielding, etc. In case of magnesium, it is mainly produced by diecasting due to high fluidity of melts. But, casting defect occurs many times because of low heat capacity of the magnesium. Therefore, wrought products can be applied for defect-free and mechanical properties. but it is insufficient in market share because of crystalline structure. The domestic market of wrought magnesium products are not revitalized compare to advanced countries. Accordingly we are going to forecast a domestic market of wrought products through searching the present of korean magnesium industry.

• 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.