• Wind and Structures
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• v.12 no.2
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• pp.89-101
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• 2009

The Monte Carlo procedure was used to simulate wind load effects on a light-frame low-rise structure of irregular shape and a main wind force resisting system. Two analytical models were studied: rigid-beam and rigid-plate models. The models assumed that roof diaphragms were rigid beam or rigid plate and shear walls controlled system behavior and failure. The parameters defining wall stiffness, including imperfections, were random and included wall stiffness, wall capacity and yield displacements. The effect of openings was included in the simulation via a set of discrete multipliers with uniform distribution. One and two-story buildings were analyzed and the models can be expanded into multiple-floor structures provided that the assumptions made in this paper are not violated.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.170-175
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• 1992

A leak detection method for diagnosis of the leak position in a pipeline was developed using an estimation theory with the assumption that the measured flow rates and pressures are stochastic processes. A notch filter was designed using power spectral density analysis of measurements to reduce the effects of disturbances. The noise model dimension was determined by hypothesis testing and then recursive extended least square method was applied to estimate the leak position in real time. The proposed method was applied to an experimental system for evaluation of its performance.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.339-347
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• 2001

A probabilistic optimum design method of the base isolation system consisting of linear spring, viscous damper and frictional element is presented. For the probabilistic approach, the base excitation is assumed to be a stationary Gaussian filtered random process. For optimum design, the objective function and constraints are derived based on the stochastic responses of the system. As a numerical example, the optimum design problem of a three-story base isolated shear type structure is formulated and solved by the sequential quadratic programming method. As a result, the effects of variation of design variables such as parameters of the base isolation system and the mass of base on the objective function and constraints are investigated and the optimum parameters of the base isolation system under study are derived.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.4
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• pp.395-400
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• 2009

As the variables affecting the fatigue behavior have uncertainty, the fatigue crack propagation is stochastic in nature. Therefore, the fatigue life prediction is critical for the design and the maintenance of many structural components. In this study, fatigue experiments are conducted on the specimens of magnesium alloy under the different thicknesses of specimen. The effects of specimen thickness on the probability distribution of the fatigue crack propagation life and the crack size are estimated experimentally. The probability distribution of the crack size and the fatigue life for different specimen thicknesses are investigated by Anderson-Darling test and the best fit for those probability distributions are also presented.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.219-226
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• 2003

The structures have intrinsic uncertainties in analysis/design parameters contrary to the assumptions of perfect constant over the structural domain. The material and geometrical parameters are the exemplary ones. The influences of uncertainties in Young's modulus, which are the representative random design variables, on the structural response have been the center of focus in the realm of stochastic analysis. In this study, a formulation to obtain the response variability due to the randomness in the Poisson's ratio is given. In that the previous researches in the literature deal with the response variability due mainly to the uncertainty in the elastic modulus, with the results of this research, it can be asserted to obtain the response variability taking into consideration of uncertainties in all the material constants becomes possible.

• Journal of ILASS-Korea
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• v.3 no.4
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• pp.65-76
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• 1998

An experimental and numerical study of a spray flow is performed to investigate the spray characteristics using an air-assisted atomizer. A Partical Dynamic Analyzer(PDA) is used to measure SMD, dmp velocity, and drop number density whose the initial conditions have considerable effect on the numerical results. The measured experimental data have been used to asses the accuracy of model predictions. Numerical investigation is made with the Eulerian - Lagrangian formulism. Turbulent dispersion effects using a Monte-Carlo method, turbulent modulation effect and entrainment of air are also numerically simulated. Results show that the numerical predictions of SSF(Stochastic Separated Flow) analysis yielded reasonable agreement with the experimental data. However, the model calculations for small drops produced the inconsistent numerical results due to the effect of surrounding air entrainment.

• Journal of Sensor Science and Technology
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• v.24 no.6
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• pp.368-372
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• 2015

In this paper, we proposed a post-processing technique for improving classification performance of electronic nose (E-Nose) system which may be occurred drift signals from sensor array. An adaptive radial basis function network using stochastic gradient (SG) and singular value decomposition (SVD) is applied to process signals from sensor array. Due to drift from sensor's aging and poisoning problems, the final classification results may be showed bias and fluctuations. The predicted classification results with drift are quantized to determine which identification level each class is on. To mitigate sharp fluctuations moving-averaging (MA) technique is applied to quantized identification results. Finally, quantization and some edge correction process are used to decide levels of the fluctuation-smoothed identification results. The proposed technique has been indicated that E-Nose system was shown correct odor identification results even if drift occurred in sensor array. It has been confirmed throughout the experimental works. The enhancements have produced a very robust odor identification capability which can compensate for decision errors induced from drift effects with sensor array in electronic nose system.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.830-835
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• 1994

In this paper, a new method of statistically evaluating an output response probability distribution of a memory type non-linear system is practically derived based on a zero-memory type non-linear equivalent system. That is, first, the objective system is approximately and functionally separated into two functional parts, i.e., a zero-memory type non-linear part and a memory type linear part according to the well-known Wiener's idea. A whole mathematical frame of the output probability distribution is evaluated in an approximate but generalized form, based on the equivalent zero-memory type non-linear part. The memory effects between the input and the output of the system are reflected in the statistical parameters and the expansion coefficients.

• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.398-404
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• 1992

We have investigated the kinetics of diffusion-influenced bimolecular reactions in which one reactant has an internal mode, called the gating mode, that activates or deactivates its reactivity intermittently. The rate law and an expression for the time-dependent rate coefficient have been obtained from the general formalism based on the hierarchy of kinetic equations involving reactant distribution functions. The analytic expression obtained for the steady-state reaction rate constant coincides with the one obtained by Szabo et al., who derived the expression by employing the conventional concentration-gradient approach. For the time-dependent reaction rate coefficient, we obtained for the first time an exact analytic expression in the Laplace domain which was then inverted numerically to give the time-domain results.

• Journal of the Semiconductor & Display Technology
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• v.22 no.1
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• pp.118-123
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• 2023

Partially magnetized capacitively coupled plasma (CCP) sources are investigated using a two-dimensional kinetic simulation code named EDIPIC-2D. A converging numerical solution was obtained for CCP with a 60 MHz power source, while properly capturing the dynamics of electrons and power absorption over a single RF period. The effects of magnetic fields with different orientations were evaluated. Axial magnetic fields caused changes in the spatial distribution of plasma density, affecting the loss channel. Transverse magnetic fields enhanced stochastic heating near the powered electrode, leading to an increase in plasma density while the significant E×B drift loss compensated for this rise.