• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.1
• /
• pp.49-57
• /
• 2002

Including RF Package inductance, substrate coupling through conductive silicon(Si)-substrate is modeled and quantitatively characterized. 2-port substrate coupling model is extended for the characterization of multi-port substrate coupling between digital circuit block and analog/RF circuit block. Furthermore, scalable parameter extraction model is developed. Multi-port substrate coupling can be investigated by linearly superposing a frequency-dependent 2-port substrate coupling model using scalable parameters. In addition, Substrate coupling including RF package inductance effect is quantitatively investigated. It is shown that package effect increases substrate coupling and shifts a characteristic frequencies(i.e., poles) to the higher frequency range. The proposed methodology can be efficiently used to the mixed-signal circuit performance verification.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.1
• /
• pp.320-324
• /
• 2015

Mutual coupling between antenna elements of a linear microstrip patch antenna array positioned along the H-plane including the effect of edge reflections is investigated. Simple formulas are presented for the estimation of the grounded dielectric substrate size with minimum mutual coupling. The substrate sizes calculated by these formulas are in good agreement with those obtained by the full-wave simulation and experimental measurement. The substrate size with minimum mutual coupling is a function of the effective dielectric constant for surface waves and the distance between the antenna centers. The substrate size with minimum mutual coupling decreases as the effective dielectric constant for surface waves on a finite grounded dielectric substrate increases.

• Journal of the Korean Ceramic Society
• /
• v.38 no.7
• /
• pp.608-614
• /
• 2001

수지결합질 탄소재의 사출성형시 중요한 요소는 열유변학적 거동이다. 수지결합질 탄소재의 열유변성, 기계적 물성은 충진제(흑연)의 표면상태에 영향을 받는다. Coupling 처리에 의한 충진제의 표면개질은 binder와의 젖음성과 호환성 등에 영향을 미쳐 수지결합질 탄소재의 특성을 향상시킨다. 본 연구에서는 충진제의 표면개질을 위해 실란 coupling 처리하였다. 충진제의 표면에 코팅된 실라놀은 FT-IR과 침수거동 관찰결과 충진제 표면에 단층으로 코팅되었음을 보였다. Coupling 처리는 충진제 표면에 활성을 가함으로써 수지결합질 탄소재의 열유변학적 거동과 기계적 물성에 기여하였다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.81-84
• /
• 2005

In order to effectively resist seismic loads, coupling beams must be sufficiently stiff, strong and posses a stable load-deflection hysteretic response. This paper reports experimental data on the seismic performance of precast HPFRCC coupling beams with variable details. Precast HPFRCC coupling beam was tested to evaluate their failure modes. shear behavior, micro crack pattern and energy dissipation. Based on the experimental results, precast coupling beam with diagonal and rhombic details offer greater performance and ductility than coupling beam with normal detail.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.156.1-156
• /
• 2001

It is observed that if the 2-gimballed seeker is stabilized using rate gyros mounted along its primary axis, line of sight change measured in the seeker is induced by the rolling due to the bank-to-turn(BTT) steering as well as the actual change. This body-coupling within BTT homing includes the spurious target maneuver effect and the coupling loop due to the rate gyro misalignment. In this paper we formulates the linear BTT homing loop model with a 2-gimballed seeker including those body-coupling effects. With the model, we analyze the effects of the couplings, and show that the roll rate coupling to the rate gyro for the stabilztion of gimbal could seriously deteriorate the homing loop stability. And we propose a direct linear compensator for the coupling to recover the stability.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.23 no.7 s.166
• /
• pp.1085-1093
• /
• 1999

Thickness effects of coupling agent on residual bending stress were investigated in $Polyimide/SiO_2$ joints during thermal cycling. Thickness and peel strength of $\gamma$-APS coupling agent were measured and correlated with solution concentration and residual bending stress. The variation of residual bending stress with temperature was also measured for various thicknesses of the coupling agent. Finite element results were compared with experimental data for residual bending stress in $Polyimide/SiO_2$ joints.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.48 no.6
• /
• pp.309-315
• /
• 1999

Coupling loss is generated by the time-varying external magnetic field in the normal matrix of the multi-filamentary HTS tape. This paper calculates the coupling loss in the HTS tape. Analytic calculation of the coupling loss cannot consider the effect of the different shapes and the arrangement of the filaments. Numerical calculation by using finite element method and analytic calculation of the coupling loss have been done in this paper and results of two calculations have been compared. Transverse magnetic field and longitudinal magnetic field were considered as the external field.

• Wind and Structures
• /
• v.34 no.5
• /
• pp.437-450
• /
• 2022

Vortex-induced vibration (VIV) is a significant concern when designing slender structures with square cross sections. VIV strongly depends on structural dynamics and flow states, which depend on the conditions of the approaching flow and shape of a structure. Therefore, the effects of the angle of attack on the coupling effects of VIV for a square cylinder are expected to be significant in practice. In this study, the aerodynamic forces for a fixed and elastically mounted square cylinder were measured using wind pressure tests. Aerodynamic forces on the stationary cylinder are firstly discussed by comparisons of variation of statistical aerodynamic force and wind pressure coefficient with wind angle of attack. The coupling effect between the aerodynamic forces and the motion of the oscillating square cylinder by VIV is subsequently investigated in detail at typical wind angels of attack with occurrence of three typical flow regimes, i.e., leading-edge separation, separation bubble (reattachment), and attached flow. The coupling effect are illustrated by discussing the onset of VIV, characteristics of aerodynamic forces during VIV, and interaction between motion and aerodynamic forces. The results demonstrate that flow states can be classified based on final separation points or the occurrence of reattachment. These states significantly influence coupling effects of the oscillating cylinder. Vibration enhances vortex shedding, which creates strong fluctuations in aerodynamic forces. However, differences in the lock-in range, aerodynamic force, and interaction process for angles of attack smaller and larger than the critical angle of attack revealed noteworthy characteristics in the VIV of a square cylinder.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.5
• /
• pp.774-781
• /
• 2013

A structural analysis was carried out for a 60 N.m class flexible disk coupling. Flexible disk couplings are used to transmit power between two shafts. When a flexible coupling is used, some amount of misalignments such as angle of deviation and end play can be allowed in assembling the shafts. However, the maximum allowable misalignment should be decided to guarantee the fatigue life. In this study, the effect of the angle of deviation and end play on the maximum stress was investigated. From the analysis results, it was shown that the angle of deviation has a greater effect on the maximum stress than the end play. Furthermore, the dimensions of the disk plate were optimized to realize a better design. From the optimization, the maximum stress could be reduced by up to 5.2%.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.7
• /
• pp.2099-2104
• /
• 2013

We present here an efficient and simple method for preparation of highly active Pd heterogeneous catalyst (CNT-Pd), specifically by reaction of dichlorobis(triphenylphosphine)palladium ($Pd(PPh_3)_2Cl_2$) with thiolated carbon nanotubes (CNTs). The as-prepared CNT-Pd catalysts demonstrated an excellent catalytic activity for the carbon-carbon (C-C) cross-coupling reactions (i.e. Suzuki, Stille, and decarboxylative coupling reactions) under mild conditions. The CNT-Pd catalyst could easily be removed from the reaction mixture; additionally, in the decarboxylative coupling of iodobenzene and phenylpropiolic acid, it showed a six-times recyclability, with no loss of activity. Moreover, once its activity had decreased by repeated recycling, it could easily be reactivated by the addition of phosphine ligands. The remarkable recyclability of the decarboxylative coupling reaction is attributable to the high degree of dispersion of Pd catalysts in CNTs. Aggregation of the Pd catalysts is inhibited by their strong adhesion to the thiolated CNTs during the chemical reactions, thereby permitting their recycling.