• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.450-453
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• 2008

During the drawing of reentrant section like a spline, the unfilled in the corner of dies or the bended product emerges from the large reduction of area, the complex shaped sections and other nonuniform properties in material and lubrication conditions. In this study, the drawing of the spline section with the non-rotary symmetry from a circular aluminum billet has been analyzed by using commercial code DEFORM-3D. A new die construction method preventing the spline from the drawback of bending and the unfilled defect has been suggested and verified through the analysis using centroid shift method and the hybrid construction between converged and diverged profile.

• Journal of Korea Multimedia Society
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• v.16 no.2
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• pp.147-159
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• 2013

In medical visualization, volume visualization is widely used. Applying 3D images to diagnose requires high resolution and accurately implement visualization techniques are being researched accordingly. However, when a three-dimensional image volume visualization is implemented using volume data, aliasing will occur since using discrete data. Supersampling method, getting lots of samples, is used to reduce artifacts. One of the supersampling methods is Catmull-rom spline. This method calculates accurate interpolation value because it is easy to compute and pass through control points. But, Catmull-rom spline method occurs overshoot or undershoot in large gradient of pixel values. So, interpolated values are different from original signal. In this paper, we propose an adaptive adjusting weights interpolation method using Gaussian function. Proposed method shows that overshoot is reduced on the point has a large gradient and PSNR is higher than other interpolated image results.

• Geophysics and Geophysical Exploration
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• v.16 no.3
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• pp.139-144
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• 2013

A computer program has been developed to estimate time-domain electromagnetic (EM) responses for a onedimensional model with multiple source and receiver dipoles that are finite in length. The time-domain solution can be obtained by applying an inverse fast Fourier transform (FFT) to frequency-domain fields for efficiency. Frequency-domain responses are first obtained for 10 logarithmically equidistant frequencies per decade, and then cubic spline interpolated to get the FFT input. In the case of phases, the phase curve must be made to be continuous prior to the spline interpolation. The spline interpolated data are convolved with a source current waveform prior to FFT. In this paper, only a step-off waveform is considered. This time-domain code is verified with an analytic solution and EM responses for a marine hydrocarbon reservoir model. Through these comparisons, we can confirm that the accuracy of the developed program is fairly high.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1167-1173
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• 2017

As the society increasingly embraces the high - tech digital information age, the field of image processing becomes progressively more branched out and becoming an imperative field. However, image data is deteriorated due to various causes during transmission and salt and pepper noise is typical. Typical methods for removing salt and pepper noise include CWMF, SWMF, and A-TMF. However, existing methods are somewhat insufficient in their ability to remove noise in salt and pepper noise environments. Therefore, in this paper, after it is determined whether noise removal is needed, the following measures were taken. If the center pixel was non-noise, the original pixel was preserved, If it was noise, we proposed a two - dimensional spline interpolation method and a median filter depending on the noise density of the local mask. For the purpose of objective judgment, we compared the results with that of existing methods and used PSNR (peak signal to noise ratio) as a judgment criterion.

• Journal of KIISE:Databases
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• v.29 no.6
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• pp.441-452
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• 2002

If continuous moving objects are managed by conventional database, it is not possible for them to store all position information changed over time in the database. Therefore, a time period of regular rate is determined and position information of moving objects are discretely stored in the system for every time period. However, if continuous moving objects are managed as discrete model, we will have problems which cannot properly answer to the query about uncertain past or future position information. To solve this problem, in this paper, we propose the method and algorithm which use the history information stored in the same database, to estimate the past or future location of moving objects. The cubic spline interpolation is used to estimate the past location and the mean movement value of the history information is used to predict the future location of moving objects. Finally, from the location estimation experimentation of using virtual trajectory and location sample, we proved that the proposed cubic spline function has less error than the linear function.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.363-370
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• 2014

A new NURBS-based shape optimization method is proposed. Most shape optimization studies consider only control point positions as design variables. Some shape optimization processes present problems with mesh quality and convergence when control points are constrained to a limited space. If the weights of the control points are regarded as additional design variables, it should be possible to attain a better degree of shape control. In this study, positions and weights of NURBS control points are used as design variables, and a shape optimization algorithm incorporates position optimization and weight optimization steps. This method is applied to shape optimization benchmarking problems to verify its advantages.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.162-171
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• 2017

Low frequency noise components causes the baseline drift in the ECG signals. In this paper, a morphological operation and smoothing spline technique are used for ECG signal processing in order to accomplish baseline correction. Removing the baseline drift from ECG signal using morphology operation, the feature of original signal may be distorted. To resolve this distortion problem, we applied a smoothing spline operation after morphology operation. In order to compare with existing morphology operation method for baseline correction, we apply proposed method to ECG data in MIT/BIH database. Compared to other existing method, our proposed method achieved low data distortion on the original signal.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.10
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• pp.1955-1960
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• 2016

Currently, with the rapid development in digital era, the image equipment related to multi-media is becoming commercialized. However, in the process of transmitting image data, deterioration occurs due to various causes, and the most representative deterioration is salt and pepper noise. There are many methods of eliminating salt and pepper noise such as SWMF, RSIF, MNRF, which are rather insufficient in eliminating noise in high-density slat and pepper noise environment. Therefore, in order to eliminate salt and pepper noise, this thesis proposes an algorithm by first judging the noise, and when the center pixel value is non-noise, the original pixel is preserved, and when it is noise, the partial mask is subdivided into 4 directions to apply cubic spline interpolation to the direction with most non-noise pixels. Also, for the objective judgement, it was compared to existing methods, and the PSNR(peak signal to nise ratio) was set as the judgement standard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.12
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• pp.2313-2327
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• 1994

As the communication environment evolves, there is an increasing need for multiresolution image coding. To meet this need, the entrophy constratined vector quantizer(ECVQ) for coding of image pyramids by spline wavelet transform is introduced in this paper. This paper proposes a new scheme for image compression taking into account psychovisual feature both in the space and frequency domains : this proposed method involves two steps. First we use spline wavelet transform in order to obtain a set of biorthogonal subclasses of images ; the original image is decomposed at different scale using a pyramidal algorithm architecture. The decomposition is along the vertical and horizontal directions and maintains constant the number of pixels required the image. Second, according to Shannon's rate distortion theory, the wavelet coefficients are vectored quantized using a multi-resolution ECVQ(entropy-constrained vector quantizer) codebook. The simulation results showed that the proposed method could achieve higher quality LENA image improved by about 2.0 dB than that of the ECVQ using other wavelet at 0.5 bpp and, by about 0.5 dB at 1.0 bpp, and reduce the block effect and the edge degradation.

• Journal of Navigation and Port Research
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• v.26 no.4
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• pp.473-479
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• 2002

The estimation of the volume of a pit excavation is often required in many surveying, soil mechanics, highway applications and transportation engineering situations. The calculation of earthwork plays a major role in plan or design of many civil engineering projects such as seashore reclamation, and thus it has become very important to improve the accuracy of earthwork calculation. In this paper the spot height method, proposed formulas(A, B, C), and chen and Line method are compared with the volumes of the pits in these examples. And we proposed an algorithm of finding a terrain surface with the free boundary conditions and both direction spline method drawback, i.e., the modeling curves form peak points at the joints. To avoid this drawback, the cubic spline polynomial was chosen as the methematical model of the new method. From the characteristics of the cubic spline polynomial, the modeling curve of the new method was smooth and matched the ground profile well. As a result of this study, algorithm of proposed three methods to estimate pit excavation volume provided a better accuracy than spot height, chamber, chen and Lin method. And the mathematical model mentioned makes is thought to give a maximum acccuracy in estimating the volume of a pit excavation.