• Title/Summary/Keyword: angle dependence

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Parametric Studies for the Optimum Design of a Hexagonal Plate Monopole Antenna

  • Park Seong-Bae;Park Joung-Min;Ahn Bierng-Chearl;Kim Kyung-Seok
    • Journal of electromagnetic engineering and science
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    • v.6 no.1
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    • pp.53-61
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    • 2006
  • In this paper, we present parametric studies for the optimum design of a hexagonal plate monopole antenna. The dependence of the antenna performance on various geometric parameters is investigated using a commercial electromagnetic software, from which an optimum design of a hexagonal plate monopole antenna is derived. Guidelines for determining initial parameter values are given. The diameter of the circular ground plane is minimized tlo 1/5 wavelength at the lowest operating frequency. The antenna impedance matching is controlled by adjusting the gap between the plate and the ground plane, the plate base width, and the base bevel angle. The antenna proposed in. this paper shows a reflection coefficient less than -10 dB and a 2.06.2 dBi gain over 320 GHz frequencies.

TOP-EMISSION CHARACTERISTICS OF ORGANIC LIGHT-EMITTING DIODES (유기발광소자의 전면 발광 특성)

  • Shin, Eun-Chul;Park, Il-Heung;Lee, Ho-Shik;Cho, Sung-Ho;Min, Hang-Gi;Kim, Tae-Wan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.06a
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    • pp.58-59
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    • 2007
  • We have fabricated top-emission. organic ligth-emitting diodes in a structure of Glass/Al/2-TNATA/TPD/Alq3/LiF/Al/Ag. By varying a film thickness of 2-TNATA and TPD, current efficiency, luminance efficiency, and viewing angle dependence of the device were measured. The top device using Alq3 showed electroluminescent peak wavelengths of 522nm and 505nm at 0 and 60 viewing angles, respectively. It is thought that a microcavity effect affects on peak wavelength position for different viewing angles.

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Chemisorption and orientation of Selenopheneon Si(100)-2×1

  • Lee, Han-Koo;Kim, Ki-Jeong;Kim, Hyeong-Do;Shin, Hyun-Joon;Kim, Bong-Soo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.372-372
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    • 2010
  • We have investigated adsorption of selenophene on Si(100) at room temperature using high resolution photoemission spectroscopy (HRPES) and near edge X-ray absorption fine structure (NEXAFS) in the partial electron yield (PEY) mode. The Si 2p, C 1s, Se 3d spectra of selenophene on Si(100) show that selenophene is nondissociatively chemisorbed on Si(100)-2×1 through [2+2] cycloaddition. NEXAFS has been conducted to characterize the adsorption geometry of selenophene on Si(100). Since the π orbital of C=C bond show good angular dependence in carbon K-edge NEXAFS spectra, the angle 53±5 determined from NEXAFS spectra. This majority structure is consistent with the [2+2] cycloaddition of selenophene to the dimer of the Si(100)-2×1 surface.

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Effect of Local Wall Thinning Defect on the Collapse Moment of Elbow (엘보우의 붕괴모멘트에 미치는 국부 감육결함의 영향)

  • Kim, Jin-Weon;Kim, Tae-Soon;Park, Chi-Yong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.4
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    • pp.402-409
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    • 2004
  • The purpose of this study is to investigate the effect of local wall thinning on the collapse of elbow subjected to internal pressure and bending moment. Thus, the nonlinear three-dimensional finite element analyses were performed to obtain the collapse moment of elbow containing various wall thinning defects located at intrados and extrados under two loading modes (closing and opening modes) with internal pressure. From the results of analysis, the effect of wall thinning defect on the global moment-rotation behavior of elbow was discussed, and the dependence of collapse moment of elbow on wall thinning depth, length, and circumferential angle was investigated under different loading mode and defect location.

Application of Multichannel Quantum Defect Theory to the Triatomic van der Waals Predissociation Process II

  • 이천우
    • Bulletin of the Korean Chemical Society
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    • v.16 no.10
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    • pp.957-968
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    • 1995
  • Generalized Multichannel Quantum Defect theory (MQDT) was implemented to the vibrational predissociation of triatomic van der Waals molecules in the previous paper [Bull. Korean Chem. Soc, 12, 228 (1991)]. Implementation was limited to the calculation of the scattering matrix. It is now extended to the calculation of the predissociation spectra and the final rotational distribution of the photofragment. The comparison of the results with those obtained by other methods, such as Golden-rule type calculation, infinite order sudden approximation (IOS), and close-coupling method, shows that the implementation is successful despite the fact that transition dipole moments show more energy dependence than other quantum defect parameters. Examination of the short-range channel basis functions shows that they resemble angle-like functions and provide the validity of the IOS approximation. Besides the validity of the latter, only a few angles are found to play the major role in photodissociation. In addition to the implementation of MQDT, more progress in MQDT itself is made and reported here.

Theory of Generation Linewidth in Spin-torque Nano-sized Auto-oscillators

  • Kim, Joo-Von;Tiberkevich, Vasil;Slavin, Andrei N.
    • Journal of Magnetics
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    • v.12 no.2
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    • pp.53-58
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    • 2007
  • Theory of the generation linewidth of a current-driven spin-torque magnetic nano-oscillator in the presence of thermal fluctuations has been developed and a simple analytical formula for the generation linewidth in the supercritical regime of generation has been derived. It is shown that the strong dependence of the oscillator frequency on the precession power leads to substantial broadening of the generation linewidth of a spin-torque oscillator compared to the case of a linear oscillator, i.e. an oscillator with power-independent generation frequency. The relation between the nonlinearity-induced broadening of the generation linewidth and the nonlinearity-induced increase of the phase-locking band of a spin-torque oscillator to an external microwave signal has been revealed. The derived expression for the generation linewidth predicts a linewidth minimum when the nano-contact is magnetized at a certain angle to its plane, at which the nonlinear frequency shift vanishes. This result is in good agreement with recent experiments.

Effect of turbulence driving and sonic Mach number on Davis-Chandrasekhar-Fermi method

  • Yoon, Heesun;Cho, Jungyeon
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.44.1-44.1
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    • 2019
  • Davis-Chandrasekhar-Fermi (DCF) method is a tool that is widely used to obtain the strength of the mean magnetic field projected on the plane of the sky. When there are independent eddies along the line of sight, the variation of polarization angle will decrease by the averaging effect. Therefore, the measured strength of the magnetic field can be overestimated. Cho & Yoo (2016) proposed a modified DCF method considering such effect. By using this, we quantitatively compared the results from the conventional DCF and the modified DCF methods for various sonic Mach numbers and driving schemes (the solenoidal and compressive driving). Here, we present that the modified DCF method does not show a strong dependence on the sonic Mach number or driving schemes either, while the conventional DCF method depends on the sonic Mach number for the compressive driving scheme.

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Fume Particle Dispersion in Laser Micro-Hole Machining with Oblique Stagnation Flow Conditions (경사 정체점 유동이 적용된 미세 홀 레이저 가공 공정의 흄 오염입자 산포특성 연구)

  • Kim, Kyoungjin;Park, Joong-Youn
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.3
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    • pp.77-82
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    • 2021
  • This numerical study focuses on the analysis of fume particle dispersion characteristics over the surface of target workpiece in laser micro-hole machining process. The effects of oblique stagnation flow over fume generating machining point are examined by carrying out a series of three-dimensional random particle simulations along with probabilistic particle generation model and particle drag correlation of low Reynolds number. Present computational model of fume particle dispersion is found to be capable of assessing and quantifying the fume particle contamination in precision hole machining which may influenced by different types of air flow patterns and their flow intensity. The particle size dependence on dispersion distance of fume particles from laser machining point is significant and the effects of increasing flow oblique angle are shown quite differently when slot blowing or slot suction flows are applied in micro-hole machining.

Synthesis of Terpolymers and Dependence of Their Characteristics on Types and Content of High α-olefin

  • Kim, Jung Soo;Kim, Dong Hyun
    • Elastomers and Composites
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    • v.55 no.4
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    • pp.263-269
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    • 2020
  • Novel flexible terpolymers with a reactive moiety were synthesized by coordination polymerization with a metallocene catalyst and a cocatalyst system. C2-symmetric rac-Et(Ind)2ZrCl2 and tri-iso-butylaluminum/dimethylanilinium tetrakis (pentafluorophenyl) borate were employed as the catalyst and cocatalyst, respectively. We synthesized reactive terpolymers consisting of ethylene, a high α-olefin content (1-hexene, 1-octene, 1-decene, and 1-dodecene), and divinylbenzene. The structure and composition of the terpolymers were characterized by 1H-nuclear magnetic resonance analysis. The catalytic activity, polymer yield, molecular weight, and molecular weight distribution were measured as functions of the chain length and high content of α-olefins. Furthermore, the thermal properties and crystallinity of the terpolymers were determined by differential scanning calorimetry and wide-angle X-ray scattering.

Reflection of plane waves from the boundary of a thermo-magneto-electroelastic solid half space

  • Singh, Baljeet;Singh, Aarti
    • Coupled systems mechanics
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    • v.10 no.2
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    • pp.143-159
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    • 2021
  • The theory of generalized thermo-magneto-electroelasticity is employed to obtain the plane wave solutions in an unbounded, homogeneous and transversely isotropic medium. Reflection phenomena of plane waves is considered at a stress free and thermally insulated surface. For incidence of a plane wave, the expressions of reflection coefficients and energy ratios for reflected waves are derived. To explore the characteristics of reflection coefficients and energy ratios, a quantitative example is set up. The half-space of the thermo-magneto-electroelastic medium is assumed to be made out of lithium niobate. The dependence of reflection coefficients and energy ratios on the angle of incidence is illustrated graphically for different values of electric, magnetic and thermal parameters.