• Journal of the Korean Society of Industry Convergence
• /
• v.9 no.3
• /
• pp.207-214
• /
• 2006

In this paper, the stability of SA(Spectral Acceleration) fragility curves is studied for the two sets of elastic modulus of concrete. In doing that, general purpose structural analysis program and generally used probability density function are used. The results of structural analysis are represented by Bernoulli distribution which says damage or no damage. By the use of Maximum Likelihood Method, two parameters of lognormal distribution - median and standard deviation - are found. With them, the fragility curves are constructed.

• Journal of the Microelectronics and Packaging Society
• /
• v.21 no.4
• /
• pp.125-131
• /
• 2014

In order to develop stretchable substrates for wearable packaging applications, the variation behavior of elastic modulus was evaluated for transparent PDMS Sylgard 184 and black PDMS Sylgard 170 as a function of the base/curing agent mixing ratio. Both for Sylgard 184 and Sylgard 170, the true elastic modulus evaluated on a true stress-true strain curve was higher more than two times compared to the engineering elastic modulus obtained from an engineering stres-sengineering strain curve, and their difference became larger with increasing the stiffness of the PDMS. Sylgard 184 exhibited a maximum engineering elastic modulus of 1.74 MPa and a maximum true elastic modulus of 3.57 MPa at the base/curing agent mixing ratio of 10. A maximum engineering elastic modulus of 1.51 MPa and a maximum true elastic modulus of 3.64 MPa were obtained for Sylgard 170 at the base/curing agent mixing ratio of 2.

• International Journal of Control, Automation, and Systems
• /
• v.5 no.1
• /
• pp.1-7
• /
• 2007

In this paper, the necessary and sufficient conditions for strict positive realness of the rational transfer functions directly from basic definitions in the frequency domain are studied. A new frequency domain approach is used to check if a rational transfer function is a strictly positive real or not. This approach is based on the Taylor expansion and the Maximum Modulus Principle which are the fundamental tools in the complex functions analysis. Four related common statements in the strict positive realness literature which is appeared in the control theory are discussed. The drawback of these common statements is analyzed through some counter examples. Moreover a new necessary condition for strict positive realness is obtained from high frequency behavior of the Nyquist diagram of the transfer function. Finally a more simplified and completed conditions for strict positive realness of single-input single-output linear time-invariant systems are presented based on the complex functions analysis approach.

• Journal of the Korean Wood Science and Technology
• /
• v.34 no.2
• /
• pp.37-45
• /
• 2006

The viscoelastic properties of blends of melamine-formaldehyde (MF) resin and poly(vinyl acetate) (PVAc) for engineered flooring used on the Korean traditional ONDOL house floor heating system were investigated by dynamic mechanical thermal analysis (DMTA). Because MF resin is a thermosetting adhesive, the effect of MF rein was shown across all thermal behaviors. The addition of PVAc reduced the curing temperature. The DMTA thermogram of MF resin showed that the storage modulus (E') increased as the temperature was further increased as a result of the cross-linking induced by the curing reaction of the resin. The storage modulus (E') of MF resin increased both as a function of increasing temperature and with increasing heating rate. From isothermal DMTA results, peak $T_{tan{\delta}}$ values, maximum value of loss modulus (E") and the rigidities (${\Delta}E$) of MF/PVAc blends at room temperature as a function of open time, peak $T_{tan{\delta}}$ and maximum loss modulus (E") values were found to increase with blend MF content. Moreover, the rigidities of the 70:30 and 50:50 MF/PVAc blends were higher than those of the other blends, especially of 100% PVAc or MF. We concluded that blends the MF/PVAc blend ratios correlate during the adhesion process.

• International Journal of Highway Engineering
• /
• v.16 no.3
• /
• pp.35-41
• /
• 2014

PURPOSES : The dynamic modulus for a specimen can be determined by using either the non-destructed or destructed testing method. The Impact Resonance Testing (IRT) is the one of the non-destructed testing methods. The MTS has proved the source credibility and has the disadvantages which indicate the expensive equipment to operate and need a lot of manpower to manufacture the specimens because of the low repeatability with an experiment. To overcome these shortcomings from MTS, the objective of this paper is to compare the dynamic modulus obtained from IRT with MTS result and prove the source credibility. METHODS : The dynamic modulus obtained from IRT could be determined by using the Resonance Frequency (RF) from the Frequency Response Function (FRF) that derived from the Fourier Transform based on the Frequency Analysis of the Digital Signal Processing (DSP)(S. O. Oyadigi; 1985). The RF values are verified from the Coherence Function (CF). To estimate the error, the Root Mean Squared Error (RMSE) method could be used. RESULTS : The dynamic modulus data obtained from IRT have the maximum error of 8%, and RMSE of 2,000MPa compared to the dynamic modulus measured by the Dynamic Modulus Testing (DMT) of MTS testing machine. CONCLUSIONS : The IRT testing method needs the prediction model of the dynamic modulus for a Linear Visco-Elastic (LVE) specimen to improve the suitability.

• Journal of applied mathematics & informatics
• /
• v.29 no.1_2
• /
• pp.451-457
• /
• 2011

The function f(z) = $e^{p(z)}$ where p(z) is a polynomial of degree n has 2n Julia lines. Julia lines of $e^{p(z)}$ divide the complex plane into 2n equal sectors with the same vertex at the origin. In each sector, $e^{p(z)}$ has radial limits of 0 or innity. Main results of the paper are concerned with maximum curves of $e^{p(z)}$. We deal with some properties of maximum curves of $e^{p(z)}$ and we give some examples of the maximum curves of functions of the form $e^{p(z)}$.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.2
• /
• pp.79-84
• /
• 2019

This paper compare the performance of CM-MMA (Constellation Matching-MMA) and RMMA (Region-based MMA) blind equalization algorithm for improve the QoS by minimizing the intersymbol interference that is occurred in nonlinear communication channel when transmitting the QAM signal. In the tap coefficient update for adaptive, CM-MMA use the error of nonconstant modulus signal adding the current MMA cost fuction and constellation matching error terms of sinusoidal power function, and the RMMA use the error by transfoms the nonconstant modulus signal of equalizer output constellation to 4-QAM constant modulus signal. They has different equalization performance by these error signal, it were compared in this paper by simulation, and performance index such as output signal constellation of equalizer, residual isi, maximum distortion, SER curves are applied for this. As a result of computer simulation, the RMMA has more better performance in the every performance index, convergence speed, residual value, noise robustness compared to CM-MMA.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.23 no.1
• /
• pp.69-78
• /
• 2007

This study was performed to compare the stress distribution pattern in the crestal cortical bone and cancellous bone using 3-dimensional finite element stress analysis when 2 different Young's modulus(high modulus, model 1; low modulus, model 2) of cancellous bone was assumed. For the analysis, a finite element model was designed to have two square-threaded implants fused together and located at first and second molar area. Stress distribution was observed when vertical load of 200N was applied at several points on the occlusal surfaces of the implants, including central fossa, points 1.5mm, 2mm, 3mm and 3.5mm buccally away from central fossa. The results were as follows; 1. In both model, the maximum Von-Mises stress in the crestal cortical bone was greater when the load was applied at the central point, points 1.5mm and 2mm buccally away from central fossa than other cases. 2. In the cortical bone around first and second molar, model 2 showed greater Von-Mises stress than model 1. It is concluded that when the occlusal contact is afforded, the distribution of stress varies depending on the density of cancellous bone and the location of loading. More favorable stress distribution is expected when the contact load is applied within the diameter of fixtures.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.8
• /
• pp.2431-2435
• /
• 1996

In order to determine the effects of hydrostatic pressure on the mechanical behavior of graphite fiber reinforced composites, the modulus, fracture stress(maximum stress), and fracture strain of graphite/epoxy composites have been determined as a function of pressure. Composite specimens used in this study were 90-deg unidirectional and had a 60% fiber volume fraction. Compressive tests under five different pressure levels were conducted. The result showed the modulus measured from as initial slope of stress-strain curve increased bilinearly with pressure with a break at 200 MPa. It was also found that fracture stress and fracture strain increased in a linear fashion with pressure.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.11
• /
• pp.4537-4556
• /
• 2020

This research was based on the study conducted by Khodaei et al. (2012), namely, the least-significant-bit (LSB) substitution combined with the pixel-value differencing (PVD) steganography, and presented an improved irreversible image steganography method. Such a method was developed through integrating the improved LSB substitution with the modulus function-based PVD steganography to increase steganographic capacity of the original technique while maintaining the quality of images. It partitions the cover image into non-overlapped blocks, each of which consists of 3 consecutive pixels. The 2nd pixel represents the base, in which secret data are embedded by using the 3-bit LSB substitution. Each of the other 2 pixels is paired with the base respectively for embedding secret data by using an improved modulus PVD method. The experiment results showed that the method can greatly increase steganographic capacity in comparison with other PVD-based techniques (by a maximum amount of 135%), on the premise that the quality of images is maintained. Last but not least, 2 security analyses, the pixel difference histogram (PDH) and the content-selective residual (CSR) steganalysis were performed. The results indicated that the method is capable of preventing the detection of the 2 common techniques.