• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.159-168
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• 2005

This study carries out a finite difference nonlinear analysis of anisotropic advanced composite plate structures with various layer sequences. In the numerical analysis of various mechanical problems involving complex partial differential equations, the finite difference method (FDM) developed in this study has an advantage over the finite element method in its ability to avoid mesh generation and numerical integration. Many studies in FDM have been made on clamped or simple boundary conditions using merely an energy approach. These approaches cannot be satisfied, however, with pivotal points along the free boundary. Therefore, this study addresses the nonlinear problem of anisotropic plates by adopting a finite difference modeling elimination of pivotal difference points in the case of a free boundary condition. Complex nonlinear behaviors of composite plate structures for various parameters, especially for layer sequences, are analyzed using the proposed approach.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.67-79
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• 1998

Inthe study, a method to evaluate the door closing sound has been developed. Based on the factor analysis, various adjective pairs which describe meaning of the door impact sound have been differentiated. This approach, called Semantic difference(SD) method, was originally developed in linguistics research on order to compare diverse mother tongue. This paper introduces at first how the door sound os generated and transmitted. After that, a factor analysis which is a tool of SD method is implemented to door closing sound for 12 domestic and 1 foreign car models. During investigation, the examined models are categorized into small, medium and luxurious size automobiles. The adjective pairs which attritbute to the door quality have been factorized into three group : expensive/ smooth, powerful/ heavy, and modern/dull. It turns out that the first factor : expensive/ smooth plays the most important role in door closing sound quality.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.7
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• pp.462-467
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• 2005

In this paper, we analyzed normal gait acceleration signal by time series analysis methods. Accelerations were measured during walking using a biaxial accelerometer. Acceleration data were acquired from normal subjects(23 men and one woman) walking on a level corridor of 20m in length with three different walking speeds. Acceleration signals were measured at a sampling frequency of 60Hz from a biaxial accelerometer mounted between L3 and L4 intervertebral area. Each step signal was analyzed using Box-Jenkins method. Most of the differenced normal step signals were modeled to AR(3) and the model didn't show difference for model's orders and coefficients with walking speed. But, tile model showed difference with acceleration signal direction - vertical and lateral. The above results suggested the proposed model could be applied to unit analysis.

• East Asian mathematical journal
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• v.23 no.2
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• pp.261-270
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• 2007

We provide a local convergence analysis for Secant-like algorithm for solving nonsmooth variational inclusions in Banach spaces. An existence-convergence theorem and an improvement of the ratio of convergence of this algorithm are given under center-conditioned divided difference and Aubin's continuity concept. Our result compare favorably with related obtained in [16].

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.221-231
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• 2004

A kinetic theory analysis is made of low-speed gas flows in a microfluidic system consisted of three microchannels in series. The Boitzmann equation simplified by a collision model is solved by means of a finite difference approximation with the discrete ordinate method. For the evaluation of the present method results are compared with those from the DSMC method and an analytical solution of the Navier-Stokes equations with slip boundary conditions. Calculations are made for flows at various Knudsen numbers and pressure ratios across the channel. The results compared well with those from the DSMC method. It is shown that the analytical solution of the Navier-Stokes equations with slip boundary conditions which is suited fur fully developed flows can give relatively good results. In predicting the geometrically complex flows up to a Knudsen number of about 0.06. It is also shown that the present method can be used to analyze extremely low-speed flow fields for which the DSMC method is Impractical.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.4
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• pp.333-341
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• 2009

In this paper arc behavior in spiral type vacuum interrupter(VI) was analyzed by means of arc images, arc voltages and finite element method(FEM). As a result of experiment, the difference of arc voltage was observed under different twisting angles. It was found that the reason of the difference was the difference of arc resistance from simultaneous analysis of arc images and arc voltages. and the difference of arc resistance was explained by Lorentz force calculation with FEM. And the results of calculation were sufficient to explain the experimental results.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.7
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• pp.163-172
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• 1996

Recently, it was reported that gaussian distribution and difference of two gaussians (DOG) to have band pass characteristics can be generated by simple iterative processes of the diffusion networks. In this paper, we propose method of improved implementation of a diffusion filter which can reduce total runing time, and operate by simple algorithm in contrast to the latest diffusion filter. We rebuild the diffusion network to a difference network which can generate DOG independently. Different filter characteristics are obtained just by each diffusion process and difference process. Quantitative analysis shows that the center frequency and the selectivity of each filter channel can be varied independently. Also, it would requires smaller amount of hardwares than conventioanl method to build a filter bank.

• Structural Engineering and Mechanics
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• v.49 no.1
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• pp.41-64
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• 2014

The main objective of this article is the exploitation of a stochastic hybrid mesh-free method based on stochastic generalized finite difference (SGFD), Newmark finite difference (NFD) methods and Monte Carlo simulation for thermoelastic wave propagation and coupled thermoelasticity analysis based on GN theory (without energy dissipation). A thick hollow cylinder with Gaussian uncertainty in mechanical properties is considered as an analyzed domain for the problem. The effects of uncertainty in mechanical properties with various coefficients of variations on thermo-elastic wave propagation are studied in details. Also, the time histories and distribution on thickness of cylinder of maximum, mean and variance values of temperature and radial displacement are studied for various coefficients of variations (COVs).

• Journal of Industrial Technology
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• v.28 no.B
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• pp.101-109
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• 2008

In general, non-stationary or chaos time series forecasting is very difficult since there exists a drift and/or nonlinearities in them. To overcome this situation, we suggest a new prediction method based on multiple model TS fuzzy predictors combined with preprocessing of time series data, where, instead of time series data, the differences of them are applied to predictors as input. In preprocessing procedure, the candidates of optimal difference interval are determined by using con-elation analysis and corresponding difference data are generated. And then, for each of them, TS fuzzy predictor is constructed by using k-means clustering algorithm and least squares method. Finally, the best predictor which minimizes the performance index is selected and it works on hereafter for prediction. Computer simulation is performed to show the effectiveness and usefulness of our method.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1621-1626
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• 2003

This study deals with the heat transfer analysis on phase change optical disc with land/groove recording by means of numerical method. Finite difference time domain(FDTD) method was used to obtain the amount of absorption of light propagating inside disc and finite difference element(FEM) method was used to calculate the temperature distribution. The calculated results present the detailed information of recording characteristics on the phase change optical disc. The temperature profiles are quite different between the land track and the groove track. The recorded mark shape on land track is smaller and more elliptic than that on groove track. It is shown that the thermal problem to the neighboring track takes place due to secondary peaks. It is found that the different write strategy should be applied to land and groove recording, respectively.