• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.113-120
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• 2007

Design optimization of layered plates bonding process is conducted by considering uncertainties in a manufacturing process, in order to reduce the crack failure arising due to the residual stress at the surface of the adherent which is caused by different thermal expansion coefficients. Robust optimization is peformed to minimize the mean as well as its variance of the residual stress, while constraining the distortion as well as the instantaneous maximum stress under the allowable reliability limits. In this optimization, the dimension reduction (DR) method is employed to quantify the reliability such as mean and variance of the layered plate bonding. It is expected that the DR method benefits the optimization from the perspectives of efficiency, accuracy, and simplicity. The obtained robust optimal solution is verified by the Monte Carlo simulation.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.6
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• pp.37-45
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• 1998

In this paper, we report the first three-dimensional simulation result of the transient enhanced diffusion(TED) of dopants in the ion-implanted silicon by employing our 3D semiconductor process simulator, INPROS system. In order to simulate three-dimensional TED redistribution of dopants in silicon, the dopant distributions after the ion implantation was calculated by Monte Carlo(MC) method, followed by finite element(FE) numerical solver for thermal annealing. Excellent agreement between the simulated 3D profile and the SIMS data has been obtained for ion-implanted arsenic and phosphorus after annealing the boron marker layer at 75$0^{\circ}C$ for 2 hours. Our three-dimensional TED simulation could successfully explain the reverse short channel effect(RSCE) by taking the 3D point defect distribution into account. A coupled TED simulation and device simulation allows reverse short channel effect on threshold to be accurately predicted.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.903-912
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• 2009

This study is focused on simulation-based dimensional tolerance optimization process (DTOP) to minimize vehicle pulls by reduction of dimensional variation in front suspension system. In previous studies, the effect of tires and wheel alignment sensitivity have mainly been investigated to eliminate vehicle pulls in nominal design condition without allocating optimal tolerance level for selected components, among various factors regarding vehicle pulls such as vehicle design parameters, vehicle weight balance, tires, and environmental factors. Unfortunately, there are wide variations in the real vehicle, and these have impacted actual vehicle pulls, especially wheel alignment effects from suspension geometry variation has not been considered in the previous studies. In the tolerance design of suspension, tolerance variables with the uncertainty such as parts dimensional variation, assembly process, datum position and direction, and assembly tool tolerance has a great influence on the variation of the suspension dimensional performances. This study introduces total vehicle pull prediction model in considering major key factors for vehicle pull sensitivity. The Monte Carlo-based tolerance analysis model using Taguchi robust method is developed to optimize dimensional tolerance parameters, satisfying on the target variation level.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.1
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• pp.43-48
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• 2006

In this Part 2, the grain growth processes of $Al_2O_3$ ceramics is numerically simulated using Monte Carlo method (MCM) and finite element method (FEM) and the pore sizes are analyzed. As the green ceramics whose thermal conductivities in high temperatures are generally low are sintered by the plasma heat and are rapidly cooled, the grain growth of the sintered body in the center is different from that in the outer. Also, even in the same sintering temperature, the pore size differs according to the pressing pressure. In order to prove the difference, the temperature distribution of the sintered body was analyzed using the finite element method and then the grain growth process associated with pressing pressures and relative densities was simulated using Monte Carlo method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.4
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• pp.351-359
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• 2015

In order to exactly evaluate the seismic collapse capacity of a structure, probabilistic approach is required by considering uncertainties related to its structural properties and ground motion. Regardless of the types of uncertainties, they influence on the seismic response of a structures and their effects are required to be estimated. An incremental dynamic analysis(IDA) is useful to investigate uncertainty-propagation due to ground motion. In this study, a 3-story steel moment-resisting frame is selected for a prototype frame and analyzed using the IDA. The uncertainty-propagation is assessed with categorized parameters representing epistemic uncertainties, such as the seismic weight, the inherent damping, the yield strength, and the elastic modulus. To do this, the influence of the uncertainty-propagation to the seismic collapse capacity of the prototype frame is probabilistically evaluated using the incremental dynamic analyses based on the Monte-Carlo simulation sampling with the Latin hypercube method. Of various parameters related to epistemic uncertainty-propagation, the inherent damping is investigated to be the most influential parameter on the seismic collapse capacity of the prototype frame.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6C
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• pp.367-377
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• 2008

As part of study to develop LRFD (Load and Resistance Factor Design) codes for foundation structures in Korea, resistance factors for static bearing capacity of driven steel pipe piles were calibrated in the framework of reliability theory. The 57 data sets of static load tests and soil property tests conducted in the whole domestic area were collected and these load test piles were sorted into two cases: SPT N at pile tip less than 50, SPT N at pile tip equal to or more than 50. The static bearing capacity formula and the Meyerhof method using N values were applied to calculate the expected design bearing capacities of the piles. The resistance bias factors were evaluated for the two static design methods by comparing the representative measured bearing capacities with the expected design values. Reliability analysis was performed by two types of advanced methods: the First Order Reliability Method (FORM), and the Monte Carlo Simulation (MCS) method using resistance bias factor statistics. The target reliability indices are selected as 2.0 and 2.33 for group pile case and 2.5 for single pile case, in consideration of the reliability level of the current design practice, redundancy of pile group, acceptable risk level, construction quality control, and significance of individual structure. Resistance factors of driven steel pipe piles were recommended based on the results derived from the First Order Reliability Method and the Monte Carlo Simulation method.

• Economic and Environmental Geology
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• v.28 no.5
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• pp.503-512
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• 1995

Groundwater flow in fracture networks is simulated using a discrete fracture (DF) model which assume that groundwater flows only through the fracture network. This assumption is available if the permeability of rock matrix is very low. It is almost impossible to describe fracture networks perfectly, so a stochastic approach is used. The stochastic approach assumes that the characteristic parameters in fracture network have special distribution patterns. The stochastic model generates fracture networks with some characteristic parameters. The finite element method is used to compute fracture flows. One-dimensional line element is the element type of the finite elements. The simulation results are shown by dominant flow paths in the fracture network. The dominant flow path can be found from the simulated groundwater flow field. The model developed in this study provides the tool to estimate the influences of characteristic parameters on groundwater flow in fracture networks. The influences of some characteristic parameters on the frcture flow are estimated by the Monte Carlo simulation based on 30 realizations.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.10
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• pp.1-10
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• 2000

A rigorous modeling of ultra-low energy implantation is becoming increasingly more important as devices shrink to deep submicron dimensions. In this paper, we have developed an efficient three-dimensional Monte Carlo ion implantation model based on a modified Binary Collision Approximation(BCA). To this purpose, the modified electronic stopping model and the multi-body collision model have been taken into account in this simulator. The dopant and damage profiles show very good agreement with SIMS(Secondary Ion Mass Spectroscopy) data and RBS(Rutherford Backscattering Spectroscopy) data, respectively. Moreover, the ion distribution replica method has been implemented into the model to get a computational efficiency in a 3D simulation, and we have calculated the 3D Monte Carlo simulation into the topographically complex structure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.3
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• pp.373-384
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• 2000

To assess the safety of nonlinear steel frame structures subjected to short duration dynamic loadings, especially seismic loading, a nonlinear time domain reliability analysis procedure is proposed in the context of the stochastic finite element concept. In the proposed algorithm, the finite element formulation is combined with concepts of the response surface method, the first order reliability method, and the iterative linear interpolation scheme. This leads to the stochastic finite element concept. Actual earthquake loading time-histories are used to excite structures, enabling a realistic representation of the loading conditions. The assumed stress-based finite element formulation is used to increase its efficiency. The algorithm also has the potential to evaluate the risk associated with any linear or nonlinear structure that can be represented by a finite element algorithm subjected to seismic loading or any short duration dynamic loading. The algorithm is explained with help of an example and verified using the Monte Carlo simulation technique.

• Tunnel and Underground Space
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• v.25 no.2
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• pp.210-219
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• 2015

This paper describes a new quantitative process for evaluating the roughness of discontinuity, which is suggested as a qualitative criteria in RMR or Q-system. For this purpose, the Delphi method which is one of the surveying methods was introduced. The selected panels were asked to evaluate the roughness of discontinuities on the Web which was hosted by authors in advance. A total of 3 surveys were performed using JRCs suggested by Barton and Choubey as well as Ai generated by the Monte Carlo simulations. After each survey, the results were provided to all panels for comparing their decisions to others. As surveys proceeded, better consensus and convergence were achieved. With a good agreement of panels on roughness classification, the quantitative criteria for roughness of discontinuity in RMR and Q-system was established in this study.