• Computers and Concrete
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• v.20 no.2
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• pp.229-246
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• 2017

The dynamic bending response of single walled carbon nanotube reinforced composite (SWCNTRC) plates subjected to hygro-thermo-mechanical loading are investigated in this paper. The mechanical load is considered as wind pressure for dynamic bending responses of SWCNTRC plate. The dynamic version of the High Order shear deformation Theory (HSDT) for a composite plate with Matrix and SWCNTRC plate is first formulated. Distribution of fibers through the thickness of the SWCNTRC plate could be uniform or functionally graded (FG). The dynamic displacement response is predicted by using Nemarck integration method. The effective material properties of SWCNTRC are estimated by using micromechanics based modeling approach. The effect of different environmental condition, volume fraction of SWCNT, Width-to-thickness ratio, wind pressure, different SWCNTRC-FG plates, boundary condition, E1/E2 ratio, different temperature on dynamic displacement response is investigated. The dynamic displacement response is compared with the available literature and it shows good agreement.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.415-423
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• 2004

To improve the brittle column behavior during seismic excitation, benefits of using steel fiber reinforced concrete in columns were investigated. For experimental study, eight specimens were used to evaluate the shear enhancement effect. The variables in this study were amount of shear reinforcement ratio (i.e., 0.26, 0.21 $\%$) and steel fiber volume fraction (i.e., 0.0, 1.0, 1.5, 2.0$\%$). The test results indicated that the maximum enhancement of shear capacity was shown in $1.5\%$ steel fiber content. In addition, to predict the maximum shear strength, equations of ACI 318-99, AIJ MB, NZS 3101, Hirosawa and Priestley were reviewed. From the parametric and regression study, modified Priestely equation was proposed by adding steel fiber effect.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.3
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• pp.132-139
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• 1984

This paper presents an exant analysis of the class E tuned power amplifier with a shunt inductor. The following performance parameters are determined for optimum operation with any switch duty ratio: the collector current and voltage waveforms, the peak values of collector current and voltage, the output power, the power output capability, and the values of the load network elements. The analysis shows that the maximum power output capability occurs at a duty ratio of 50 percent. The measured collector efficiency of experiments is 93 percent with 0.93W at 1MHz. This amplifier is especially applicable at portable transmitters because its colletor efficiency is extremely high.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.455-462
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• 2016

The electron transport coefficients in not only pure atoms and molecules but also in the binary gas mixtures are necessary, especially on understanding quantitatively plasma phenomena and ionized gases. Electron transport coefficients (electron drift velocity, density-normalized longitudinal diffusion coefficient, and density-normalized effective ionization coefficient) in binary mixtures of TEOS gas with buffer gases such as Kr, Xe, He, and Ne gases, therefore, was analyzed and calculated by a two-term approximation of the Boltzmann equation in the E/N range (ratio of the electric field E to the neutral number density N) of 0.1 - 1000 Td (1 Td = 10⁻¹⁷ V.cm²). These binary gas mixtures can be considered to use as the silicon sources in many industrial applications depending on mixture ratio and particular application of gas, especially on plasma assisted thin-film deposition.

• Transactions of the Korean Society of Mechanical Engineers
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• v.4 no.3
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• pp.113-118
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• 1980

Stresses were calculated for finite-width orthotropic laminates with a circular hole and remote uniaxial loading using a two-dimensional finite-element analysis with both uniform stress and uniform displacement boundary conditions. Five different laminates were analyzed: quasi-isotropic [0.deg./.+-.45.deg./90.deg.].$\_$s/, 0.deg., 90.deg., [0.deg./90.deg.]$\_$s/, and [.+-.45.deg.]$\_$s/, Computed results are presented for selected combinations of hole diameter-sheet-width ratio d/w and length-to width ratio L/w. For small L/w values, the stress-concentration factors K$\_$tn/ were significantly different for the uniform stress and uniform displacement boundary conditions. Typically, for the uniform stress conditions, the K$\_$tn/ values were much larger than for the infinite-strip reference conditions; however, for the uniform displacement conditon, they were only slighty smaller than for this reference. The results for long strips are also presented as width-correction factor. For d/w.leg.33, these width-correction factors are nearly equal for all five laminates.

• Geomechanics and Engineering
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• v.4 no.4
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• pp.229-241
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• 2012

In this paper, utilizing void ratio-effective stress and void ratio-permeability relationships, a system of two nonlinear partial differential equations is derived to predict the consolidation characteristics of normally consolidated (NC) and overconsolidated (OC) soft clays subjected to cyclic loading. A developed feature of the coefficient of consolidation containing two key parameters is emerged from the differential equations. Effect of these parameters on the consolidation characteristics of soft clays is analytically discussed. It is shown that the ratios between the slopes of e-$log{\sigma}^{\prime}$ and e-log k lines in the NC and OC states play a major role in the consolidation process. In the companion paper, the critical assumptions made in the analytical discussion are experimentally verified and a numerical study is carried out in order to examine the proposed theory.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.11
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• pp.2942-2953
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• 1996

This paper studies the effect of intersymbol interference due to sampling-time jitter on the worst-case bit error probability in a digital modultation over an additive white Gaussian noise channel, with the squared-root raised-cosine filters in the transmitter and the receiver. It derives approximation formulas using the Taylor series approximations. the principal results of this paper is the relationship between the worst-casse bit error probability, the degree of jitter, the roll factor of the raised cosine filter, and other quantities. Numerical results show, as expected, that the intersymbol interference decreases as the roll-off factor increases and the jitter decreases. They also show that the approximation formulas are accurate for smally intersymbol interference, i.e., for large roll-noise ratio $E_{b/}$ $N_{0}$.leq.7 dB and begin to lose accuracy for larger signal-to-noise ratio.o.o.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.178-179
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• 2005

Numerical and experimental investigation of incompressible turbulent flow and heat transfer through square channels with varying number of ribbed walls were conducted to determined pressure drop and heat transfer. The CFX solver used for the computation. The rough walls have a $45^0$ inclined square rib. Uniform heat flux is maintained on whole inner heat transfer channel area. The numerical results agreed well with experimental data that obtained for 7600$D_h$) of 0.0667. The results show that values of local heat transfer coefficient and friction factor increase with an increasing number of ribbed walls.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.241-247
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• 2001

A comparison of fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with ones roughened by five different shapes. The effects of rib shape geometries and Reynolds number are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at e/De=0.0476, P/e=8, and W/H=2.33, respectively. To understand the mechanisms of the heat transfer enhancements, the measurements of the friction factors are also conducted in the smooth and rough channels. The data indicates that the triangular type rib has a substantially higher heat transfer performance than any other ones in the range we studied.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.3
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• pp.459-466
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• 2000

Flow characteristics of turbulent elliptic jets were experimentally investigated using a single-frame PIV system. A sharp-edged elliptic nozzle with aspect ratio(AR) of 2 was tested and the experimental results were compared with those of circular jet having the same equivalent diameter($D_e$). The Reynolds number based on the nozzle exit velocity and nozzle equivalent diameter was about $1{\times}10^4$. The spreading rate along the major and minor axis are different remarkably. The jet half width along the major axis decreases at first and then increases with going downstream. But along the minor axis the jet width increases steadily. The elliptic jet of AR=2 has one switching points at $X/D_e=2$ within the near field. Turbulence properties are also found to be significantly different along the major and minor axis planes.