• Journal of electromagnetic engineering and science
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• v.12 no.4
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• pp.280-286
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• 2012

The conventionally classified waves are reclassified in this paper, including the waves associated with metamaterial (MTM) transmission lines. Various types of guided waves in periodic structures are analyzed for 1D Composite Right/Left Handed (CRLH) transmission lines (TL). In addition, dispersion diagrams for 1D CRLH, RH, and LH TLs are presented in terms of radiation conditions. We have refined the design equations of the conventional 1D CRLH TL and proposed a condition to realize the desired phase shift and its slope per unit cell. This condition has been applied to the conventional Wilkinson power divider and realized into MTM added $90^{\circ}$ hybrid coupler. Based on the 10 dB return loss and the $90{\pm}10^{\circ}$ phase shift, the bandwidths of the MTM added $90^{\circ}$ hybrid coupler are 82.25% and 103.5% against the conventional 23% and 52.5%, respectively.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.171-174
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• 2010

In the paper, a printed dual-dipole array antenna is presented. A 4-way planar SIW power divider is adopted for feeding the array antenna. The dual-dipole is adopted as radiation elements which greatly improves the impedance band. The measured bandwidth larger than 31 % for VSWR$\leq$1.5 operating near 14 GHz is achieved and in agreement with the simulated results. The radiation E-plane and H-plane radiation pattern is presented in the paper. The radiation gain is also presented in the paper.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.175-178
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• 2010

In this paper, a millimeter-wave multi-beam antenna is studied by rotating the antipodal linear tapered slot antenna(ALTSA) with respect to a center is successfully designed. In order to lowering the SLL and enhancing the isolation between the ALTSA elements, a row of metallic via is inserted between the ALTSAs. A 9 beams antenna is designed and experimented at Ka band. The measured and simulated results agree well with each other. The antenna can provide horizontal wide angle coverage up to ${\pm}62^{\circ}$. The gain of each beam can achieve about 12.5 dB. The mutual coupling between ports is all below 20 dB.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.35-35
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• 2003

In satellite communication, attenuation, scattering, and depolarization of relatively high frequency waves such as millimeter waves are strongly influenced by rain. In order to study the rain attenuation, we introduce a new theoretical method, which enables us to obtain the reflection and transmission coefficients in arbitrary medium. We adopt this method to examine how the electromagnetic radiation is affected by homogeneous spherical raindrops. It is assumed that the raindrop shape is spherical and linearly locate in one direction. For the radiation of wave in raindrops, we consider the effective permittivity, in which the raindrop is assumed to be spherical. By adopting the invariant imbedding approach, the 1st order differential equations are derived for the reflection and transmission coefficients. We investigate the transmission and reflection of waves for various incident angles when the spherical raindrops are assumed to have random sizes.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.11
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• pp.624-629
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• 2004

The UHF electromagnetic waves excited by PD pulses propagate along the GIS busbar not only TEM mode, but also TE and TM mode. Generally the waves detected by the UHF sensors are those of high order modes and such waves can only propagate higher than cut-off frequency. In this paper, the cut-off frequency of 362[kV] GIS for each modes is computed and the electromagnetic field of each propagation modes is simulated by FEM(Finite Element Method) program. Frequency band of each TEmn/TMmn modes was determinated by simulation results and was discussed optimal position of UHF sensor from this results.

• Carbon letters
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• v.12 no.1
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• pp.48-52
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• 2011

The conducting polymer-coated multi-walled carbon nanotubes (MWCNTs) were prepared by template polymerization of aniline and pyrrole on the surface of MWCNTs in order to develop the novel electromagnetic interference (EMI) shielding materials. The conducting polymer phases formed on the surface of MWCNTs were confirmed by field emission-scanning electron microscopy and field emission-transmission electron microscopy. Both permittivity and permeability were significantly improved for the conducting polymer-coated MWCNTs due to the intrinsic electrical properties of MWCNTs and the conducting properties of coated polymers. The electromagnetic waves were effectively absorbed based on the permittivity nature of conducting polymer and MWCNTs preventing the secondary interference from reflecting the electromagnetic waves. The highly improved EMI shielding efficiency was also obtained for the conducting polymer-coated MWCNTs showing the synergistic effects by combining MWCNTs and the conducting polymers.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.10
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• pp.492-499
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• 2002

This paper presents the method for an estimation of discharge current waveform in short gap discharge by radiated electromagnetic fields. The method of current waveform estimation is to use the one antenna method (single field method) with a measured electric or magnetic field at given field point by a time domain antenna. In order to verify the availability of the estimation theory, the discharge current waveform estimation was performed by one antenna methods using the measured electric fields of Wilson & Ma and compared with experiments. In addition diagnosis technique for power equipments is able to prevent from large accidents by finding signs of tile accidents before they happen. From the results of the estimation of discharge current, we have a possibility for the application of insulation diagnosis technique for power equipments using S$F_6$ gas. From this point of view, this paper simulated discharge progress and partial discharge by using needle-plan electrodes system in S$F_6$, studied the distribution of frequency spectrum of the radiated electromagnetic waves using a biconical antenna and a spectrum analyzer. From the experimental results of this study, according to the consideration of the mutual relation between frequency spectrum of the radiated electromagnetic waves and discharge progress, it was confirmed that detecting Partial discharge and estimating discharge progress in S$F_6$ could be Possible.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.9
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• pp.18-24
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• 2007

When faults occur in the power equipment that is used a great deal in industrial sites, it may lead to fatal accidents that cause losses both economically and in manpower. In this paper, the effect of particle impact on the partial discharge of $SF_6$ gas was measured by simulating a partial discharge following the type of fault found in the GIS using $SF_6$ insulating gas as the insulating material. A spectrum analysis was performed on the radiate electromagnetic waves emitted upon partial discharge by using the UHF insulation diagnosis method. This subject of this study is insulation diagnosis by the measurement of radiate electromagnetic waves when particles exist in the GIS and power equipment insulated with $SF_6$ gas.

• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.470-474
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• 2006

In the case of dryer tendency that select directly without being serviced with salesperson's opinion specially because it does Purchase with sufficient knowledge is package of goods being high and labeling for goods of consumers are indicated to very important element This development wishes to escape and use "Seramik heater" and apply electromagnetic waves cover skill to be Hair Drier that head of a family electromagnetic waves are happened in method and household electric appliance that can raise sexual intercourse of circle infrared rays and High efficiency quantity of heat and coincide in high efficiency and All function anger request in existent metal heat ray.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.248-251
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• 2014

As more vehicles become equipped with advanced electronic control systems, more consideration is needed with regards to automotive safety issues related to the effects of electromagnetic waves. Unwanted electromagnetic waves from the antenna, electricity and other electronic devices cause the performance and safety problem of automotive components. In general, Power Integrity and Signal Integrity analysis have been widely used, but these analyses have stayed PCB level. PCB base analysis is different from radiated emission TEST condition so its results are used just for reference. This paper proposes EMC optimization technology using module level 3-dimensional radiation simulation process closed to fundamental test conditions. If module level EMC analysis, which is proposed in this study, is applied to all automotive electronics systems, unexpected EMC noise will be prevented.