• Coupled systems mechanics
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• v.6 no.1
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• pp.97-111
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• 2017

The present paper reports an analytical study of delamination fracture in the Mixed Mode Flexure (MMF) functionally graded beam with considering the material non-linearity. The mechanical behavior of MMF beam is modeled by using a non-linear stress-strain relation. It is assumed that the material is functionally graded along the beam height. Fracture behavior is analyzed by the J-integral approach. Non-linear analytical solution is derived of the J-integral for a delamination located arbitrary along the beam height. The J-integral solution derived is verified by analyzing the strain energy release rate with considering the non-linear material behavior. The effects of material gradient, crack location along the beam height and material non-linearity on the fracture are evaluated. It is found that the J-integral value decreases with increasing the upper crack arm thickness. Concerning the influence of material gradient on the non-linear fracture, the analysis reveals that the J-integral value decreases with increasing the ratio of modulus of elasticity in the lower and upper edge of the beam. It is found also that non-linear material behavior leads to increase of the J-integral value. The present study contributes for the understanding of fracture in functionally graded beams that exhibit material non-linearity.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10a
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• pp.847-850
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• 1987

In this paper a new method to correct the differential non-linearity(D NL) error for a successive approximation is proposed. The DNL of ADC is very important characteristic in the field of radiation pulse height analysis or measurement of probability density function. The results of computer simulations are shown to demonstrate the feasibility of the proposed correction method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.169-170
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.579-580
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• 2007

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.103-106
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• 2005

The material properties of membrane for stratospheric airship is experimentally investigated. Mechanical tensile properties of the membrane material at room, high and low temperature are measured using instron with thermal chamber. Experimentaly, material non-linearity is observed at room and high temperature. In order to simulate material non-linearity caused by the uniaxial extension curve of a woven fabric, the nonlinear hyperelastic problem is considered with finite clement program of ABAQS. Numerical results are compared with experimental results.

• Journal of the Korea Convergence Society
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• v.7 no.3
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• pp.77-85
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• 2016

We propose a digital signal processing technic that can compensate the non-linearity inherent in audio amplifiers, and present the result of the simulation. The inherent non-linearity of the audio power amplifier arising from analog devices is compensated via a digital signal processing technic consisting of indirect learning architecture and an adaptive filter. The simulation results show that the compensator can be realized using a third-order polynomial and compensates odd-order non-linearity efficiently. The even-oder non-linearity is mainly due to the dc offset at the output, which is difficult to eliminate with the proposed method. Care must be taken in designing the bias circuit to avoid the DC offset at the output. The proposed technic has significance in that digital signal processing technic can compensate for the impairment that is an inherent characteristic of an analog system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.420-423
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• 2015

This paper proposes a method of non-linearity error detection and calibration for binary-weighted charge-driven DACs. In general, the non-linearity errors of DACs often occur due to the mismatch of layout designs or process variation, even when careful layout design methods and process calibration are adopted. Since such errors can substantially degrade the SNDR performance of DAC, it is crucial to accurately measure the errors and calibrate the design mismatches. The proposed method employs 2 identical DAC circuits. The 2 DACs are sweeped, respectively, by using 2 digital input counters with a fixed difference. A comparator identifies any non-linearity errors larger than an acceptable discrepancy. We also propose a calibration method that can fine-tune the DAC's capacitor sizes iteratively until the comparator finds no further errors. Simulations are presented, which show that the proposed method is effective to detect the non-linearity errors and calibrate the capacitor mismatches of a 12-bit DAC design of binary-weighted charge-driven structure.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.28-34
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• 2010

All pixels of image sensor do not react uniformly when the light of same radiance enters into the camera. This non-uniformity has a direct influence on the image quality. However we can overcome it by calibration process under the special test-setup. Usually it is used the algorithm to get the correction coefficients under the specific illumination condition. But, this method has drawback in the very low or very high illumination due to pixel non-linearity. This paper describes the robust algorithm, which calculates the correction coefficients based on the pixel non-linearity model, against thew hole radiance. The paper shows the non-uniformity test results with the own camera and the specified test equipments as well. The results shows the best performance over the entire radiance when this method is applied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.690-695
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• 2005

Flexible circular cantilever beams when excited externally introduce a lot of dynamic characteristics. The non-linear elements that these flexible beams develop include non-linearity due to inertia terms, spring, and damping. They show different characteristics of motion from each other. In the modes of lower order, the non-linearity due to spring is prevalent, while the non-linearity due to inertia Is prevalent in the modes of higher order. To analyze these effects the non-linear phenomena are analyzed experimentally. When the response characteristics of non-linear vibration are analyzed using autospectrum, it is possible to analyze the subharmonic and superharmonic mot ion by comparison. The phase change is analyzed using the method of phase portrait and the non-linear characteristics of response characteristics that are developed in flexible structures can be predicted and applied to the stage of design.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1011-1011
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• 2001

In general, NIR reflectance spectra (whether recorded using log(1/R) or the Kubelka-Munk function) are not linear functions of the concentration of the absorbers which we are measuring. There are several causes for this non-linearity, the most commonly cited one being front surface reflection. However, non-linearity also arises from the effects of particle size, sample thickness, void fraction, and experimental arrangement. In this talk, we will attempt to isolate the effects of the various causes, and show the effects of each, using both theoretical calculations and actual data. The listener should then be able to assess where we stand in our quest to produce “linear” data through pre-processing and/or alternate collection schemes.