• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.4
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• pp.396-403
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• 2004

The dielectric properties of Y-ray irradiated and thermally aged polyetheretherketone (PEEK) have been investigated. Results of the temperature dependency of dielectric properties indicated that the glass transition temperature of aged PEEK increased as radiative and thermal ageing. The frequency dependency of dielectric properties implied that the magnitude of radiation and thermal induced dipoles, ions increased as radiative and thermal ageing. The values of relaxation intensity calculated using Cole-Cole's circular arc can be useful for evaluation of degradation level of PEEK.

• Korean Journal of Materials Research
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• v.20 no.1
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• pp.7-11
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• 2010

Yttria stabilized zirconia (Y-CSZ) single crystals show plastic deformation at high temperatures by activating dislocations. The effect of strain rate on the plastic behavior of this crystal was studied. As increasing strain rate from $\varepsilon=1.04\times10^{-5} sec^{-1}$ to $2.08\times10^{-5} sec^{-1}$ the yield drop was suppressed and resulted in higher Young's modulus and yield stress. Dislocation structures of the strained crystals were analyzed using a transmission electron microscope to elucidate the plastic behavior of these crystals. In the early stage of plastic deformation, dislocation dipoles and prismatic dislocation loops were formed in both samples. However, dislocation density was increased by increasing strain rate. Strong sessile dislocations were observed in the sample with higher strain rate, which may cause the higher work hardening.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.1
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• pp.3-9
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• 1995

An isotropic electric-field probe, capable of characterizing and quantifying electromagnetic field, was fabricated. The probe consists of three short dipole antennas, a beam-lead Schottky diode and the high resistive transmission line. In order to get the isotropic response three mutually orthogonal dipoles are configured to form the probe. The probe's short dipole elements allow measurements of electric fields from 300MHz to 2GHz with a flatness of .+-. 2.9dB. The mutually orthogonal dipole configration shows a .+-. 1.2dB deviation in the isotropic response with respect to angle.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.59-65
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• 2000

This paper describes the characteristics of a one dimensional narrow-wall slotted waveguide array with a single-layer linear-to-circular polarization converter consisting of a dipole array. An external boundary value Problem of one slot and three dipoles, which approximates the mutual coupling between the dipole array and an edge slot extending over three faces of a rectangular waveguide, is formulated and analyzed by the method of moments; design of polarization conversion is conducted for this model as a unit element. If every unit element has perfect circular polarization, grating lobes appear in the array pattern due to the alternating slot angle: these are suppressed in this paper by changing the dipole angle and degrading the axial ratio of the unit element. The validity of the design is confirmed by the measurements. The dipole array has negligible effects upon slot impedance; the polarization conversion for existing narrow-wall slotted arrays is realized by add-on dipole array.

• Analytical Science and Technology
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• v.11 no.1
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• pp.20-28
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• 1998

Fluorimetric and absorption spectroscopic studies were performed to elucidate the photocurrent decay with time in the conversion process of solar energy into electrical energy using a photoelectrochemical cell containing rose bengal as a sensitizer, and allylthiourea as a supersensitizer. Spectra of dye solution before and after irradiation revealed a new photocatalytic dimerization reaction between sensitizer and supersensitizer. It was also found that the geometrical arrangement of the transition dipoles is oblique in the dimer of dye molecules.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.472-474
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• 2004

In this study, we investigated the characteristics of the input impedance and the gain of a ‘Folded dipole antenna with stub’ by the Method of Moments. The center frequency in this study is 200MHz, the radius of wire is 0.5nm, and the distance between two linear dipoles is 2cm. The inside variation of stub length within 18cm and the outside variation of stub length 4.5cm ive the value of SWR(Standing Wave Ratio) within 3. This means that the impedance matching between the ‘Folded dipole antenna with stub’ and receiver can easily be performed without a supplementary matching circuit.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.2
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• pp.145-149
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• 2006

UHF band omnidirectional antennas for RFID tag were designed. Crossed loaded dipole and bended dipole were applied to be designed for both miniaturization and omnidirectional radiation pattern. By suppling 90 degrees phase difference between crossed dipoles, omnidirectional E-plane patterns can be obtained. -10 dB reflection coefficients of 3 types dipole antenna which have designed under conjugate matched with input impedance of chip were shown as 670-1,050 MHz, 700-1,250 MHz and 600-1,020 MHz, respectively, and also shown that all antenna have omnidirectional radiation pattern both E and H plane.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.357-357
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• 2010

Using ab initio density functional theory, we study the structural and electronic properties of interface between Cu surface and highly electron withdrawing hexaazatriphenylene-hexanitrile (HAT-CN) known as an efficient hole injection layer for organic light emitting diodes (OLEDs). We calculate the equilibrium geometries of the interface with different HAT-CN coverages. Usually, some of C-N bonds located at the edge of the HAT-CN molecule are deformed toward Cu atoms resulting in the reconstruction of Cu surface. By analyzing the electron charge and the potential distributions over the interface, we observe the formation of surface dipoles, which modify the work function at the interface. Such dipole formation is attributed to two origins, one of which is a geometrical nature and the other is a bond dipole. The former is related to structural deformation mentioned above, whereas the latter is due to charge transfer between organic and metal surface.

• Proceedings of the KAIS Fall Conference
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• 2008.05a
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• pp.234-236
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• 2008

본 논문에서는 비행체 보호를 위해 널리 사용되고 있는 채프를 설계 할 때 효과적인 다이폴의 개수를 예측하기 위한 이론적인 계산이 수행 되었다. 채프를 레이더 사용주파수 전 대역(2~12GHz)에서 다이폴 안테나로 가정하고, 다이폴 안테나의 산란특성 분석을 통하여 레이더 반사단면적(RCS : Radar Cross Section)를 예측하였다. 기존에 소개된 이론을 기초로 Matlab을 이용한 RCS 계산 프로그램을 사용하여 계산한 결과를 비교 하였다.

• Bulletin of the Korean Chemical Society
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• v.8 no.2
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• pp.115-118
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• 1987

The angular dependence of polarization of the A-band emission from RbCl:$Pb^{2+}$ is measured at 13.4 K to determine the symmetry axes of the $Pb^{2+}-v^-_c$ dipoles. The results indicate that these centers posess tetragonal symmetry. This implies that $v^-_c$ is situated in the next-nearest-neighbor (nnn) position to the $Pb^{2+}$ ion. The polarization ratio of the A-band emission measured at various temperatures is found to be independent of the temperature. The temperature independence of polarization confirms that, for the ion, the Jahn-Teller effect reduced by strong spin-orbit interaction does not give rise to thermal depolarization.