• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.10-17
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• 2002

A study on the dynamic ground effect on three-dimensional wings is done using an indirect boundary element method(unsteady panel method). An integral equation is obtained by applying Green's theorem on all surfaces of the fluid domain. Constant strength dipole and source panels arc distributed on a wing's surface. The wake sheet is represented by constant strength dipoles. At each time step, a row of wake panels is assumed to be convected from the trailing edge of the wing. The tip vortex behind wings in dynamic ground effect moves outward. The amplitudes of the aerodynamic coefficients for the wings in dynamic ground effect are augmented much more comparing to the case in static ground effect.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.255-258
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• 2003

Recently, Digital Watermarking is used to authenticate data and to determine whether the data are distorted or not in medical images which is digitalized. The Fourier Mellin method using the Fourier Transform and the Log-Polar coordinate transform gets an invariant feature for RST distortion in images. But there are several problems in the real materialization. Interpolation of the image value should be considered according to the pixel position and so a watermark loss, original image distortion, numerical approximation is happened. Therefore there should be solved to realization of the Fourier Mellin method. Using the Look up table, there reduce the data loss caused by the conversion between Rectangular and Polar coordinate. After diagnose, medical images are transformed the Polar coordinate and taken the Discrete Fourier transform in the center of ROI region. Maintaining the symmetry in Fourier magnitude coefficient, the gaussian distributed random vectors and binary images are embedded in medical images.

• MALSORI
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• no.66
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• pp.1-20
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• 2008

The purpose of this study was to investigate the characteristics of fundamental frequency(F0) and amplitude distributions in persons with cerebral palsy(CP) in the reading task. Participants were divided into three groups: 6 persons with spastic CP, 6 persons with athetoid CP and 6 normal persons who are around 15-20 years old. On the results of this study, firstly, in F0 distributions, most of the spastic CPs tended to appear narrow distributions on the basis of mode, but most of the athetoid CPs were opposite, and both of the CP groups tended to distribute highly on lower and higher frequencies than mean and mode. On the other hand, normal persons had a tendency to appear narrow distributions on the basis of mode. Finally, in amplitude distributions, the spastic CPs showed a tendency that there are little differences between the distribution of mode and the others, and most of the athetoid CPs showed a tendency that the distributions of mode were higher than the others. In addition to, the normal persons had a tendency that the distributions of mode were remarkably higher than both of the CP groups.

• Water for future
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• v.16 no.4
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• pp.221-236
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• 1983

In semi-enclosed shallow sea areas typified by the Yellow sea and the East China Sea, currents and sea surface variations are predominantly tidal. During the recent years two-dimensional numerical hydrodynamic model of the Yellow Sea and the East China Sea has been developed, based on the vertically-integrated equations of motion and continuity, capable of reproducing amplitudes and phases of the principal components of tides to satisfiable accuracy. As a subsequent development a three-dimensional hydrodynamical nymerical model covering the Yellow Sea and the East China Sea has been formulated to investigate the vertical distribution of horizontal tidal current and the response of the continented to investigate the vertical distribution of horizontal tidal current and the response of the continental shelf sea to steady uniform wind stress field imposed over the surface. Features of the M2 tidal current and the wind-induced three-dimensional current structure determined from the computation have been examined and discussed.

• The Journal of Information Technology
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• v.2 no.2
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• pp.13-22
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• 1999

In this paper, we purpose automatic diagnosis in online, as the fundamental study to diagnose the partial discharge mechanism and to predict the lifetime by introduction a neural network. In the proposed method, we use AE(acoustic emission) sensing system and calculate a quantitative statistic parameter by pulse number and amplitude. Using statically parameters such as the center of gravity(G) and the gradient if the discharge distribute(C), we analyzed the early stage and the middle stage. the quantitative statistic parameters are learned by a neural network. The diagnosis of insulation degradation and a lifetime prediction by the early stage time are achieved. On the basis of revealed excellent diagnosis ability through the neural network learning for the patterns during degradation, it was proved that the neural network is appropriate for degradation diagnosis and lifetime prediction in partial discharge.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.599-606
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• 1988

Structures of interfacial waves in nearly-horizontal countercurrent stratified air-water flow have been measured by means of a needle contact method. Based upon a statistical analysis for the liquid film distribution, statistical properties of the waves such as mean film thickness, mean wave amplitude and rms value of the wave fluctuation have been calculated. The results show that the film distribution can be described by a Gaussian probability density function for the three-dimensional wave regime. It is also indicated that the mean film thick ness and the rms value of the wave fluctuation increase as gas and liquid flow rates are increased in countercurrent two-phase flow. The dimensionless intensity of the wave fluctuation may be regarded as a function of the Froude number and the dimensionless mean film thickness.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.2
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• pp.77-84
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• 1994

This paper is measured partial discharge of low density polyethylene by using acoustic emission measuring method when the electrical tree grow its length in LDPE. Acoustic emission's pulses and its amplitudes of partial discharge are measured by acoustic emission measuring devices. Theorem of skewness are used for breakdown prediction of LDPE. So, it is found that the breakdown of LDPE could be predicted by its skewness's value. There are two kind of specimen of no void and specimen of artificial void, this one's electrical tree grows very faster than that one's.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.6
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• pp.477-483
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• 1987

We constructed the tidal chart of $M_2$ tide in the East Sea (Japan Sea) by an objective method. The sea level elevations at coastal stations are specified as Dirichlet boundary conditions, and the tidal constants inside of the East Sea basin are determined by the solution of the complex partial differential equation for the sea surface elevation. We studied the influences of the bottom topography and the tidal friction on the distribution of tidal chart inside of the basin. Using the results of basin-wide tidal model, we constructed a detailed tidal chart of the Ma tide off east of Korea.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.7
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• pp.37-47
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• 1995

In this paper, we have measured eletromagnetic noises from eletcric trains and the measurment data are treated statisticlly for monig. In order to measure the noise of electric tran, we set up an automatic measuring system andd measured the magnetic field over 9 kHz ~ 30 MHz range and electric field over 30 MHz - 1, 000 MHz range. The computer controlled measurint system yields efficiently experimental APD (Amplitude Probability distribution) data each of national rail road and subway train. The measured APD curves are analysed in terms of sensitivity study of Middleton's model through 6-parameter variation. Optimal parameters are obtained from measured data using Composite Approximation Algorithm.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.4
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• pp.164-168
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• 2007

In this paper, we propose the eye detection algorithms which can apply to the Real-Time Embedded systems. To detect the eye region, the feature vectors are obtained at the first step and then, PCA(Principal Component Analysis) and amplitude projection method is applied to composite the feature vectors. In the decision state, the estimated probability density functions (PDFs) are applied by the proposed Bayesian method to detect eye region in an image from the CCD camera. The simulation results show that our proposed method has a good detection rate on the frontal face and this can be applied to the embedded system because of its small amount of the mathematical complexity.