• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.179-191
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• 2013

The quincunx lattice is a non-separable sampling method in image processing. It treats the different directions more homogeneously and good frequency property than the separable two dimensional schemes. The high density discrete wavelet transformation is one that expands an N point signal to M transform coefficients with M > N. In two dimensions, this transform outperforms the standard discrete wavelet transformation in terms of shift-invariant. Although the transformation utilizes more wavelets, sampling rates are high costs. This paper proposed the high density discrete wavelet transform using quincunx sampling, which is a discrete wavelet transformation that combines the high density discrete transformation and non-separable processing method, each of which has its own characteristics and advantages. Proposed wavelet transformation can service good performance in image processing fields.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.5
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• pp.118-125
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• 2002

The previous kinematic analysis of wheeled mobile robots(WMRs) is performed in an ad-hoc manner, while those of the robot manipulators are done in a consistent way using the coordinate system assignment and the homogeneous transformation matrix. This paper shows why the method for the robot manipulators cannot be used directly to the WMRs and proposes the method for the WMRs, which contains modeling the wheel with the Sheth-Uicker notation and the homogeneous transformation. The proposed method enable us to model the velocity kinematics of the WMRs in a consistent way. As an implementation of the proposed method, the Jacobian matrices were obtained for conventional steered wheel and non-steered wheel respectively and the forward and inverse velocity kinematic solutions were calculated fur a tricycle typed WMR. We hope that our proposed method comes to hold an equivalent roles for WMRs, as that of the manipulators does for the robot manipulators.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.4
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• pp.586-593
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• 2010

In this paper, I have proposed that the 1st and 2nd AC-DC transformation methods using multi-level pulsating currents and selection switches. Through making the rectified voltage of the proposed AC-DC translation which is similar to reference voltage by selecting from multi-level pulsating currents, the proposed translation has dramatically reduced the ripple voltage. I have compared the performance of the DC voltage, the ripple voltage and the peak to peak voltage of the proposed method with the conventional method. The simulation results show that the proposed 2nd method has the better performance than the 1st method in the point of average DC voltage drop and peak to peak voltage increase.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.597-605
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• 2019

This paper proposes a novel method for efficient prediction of joint distributions of heights and periods of nonlinear ocean waves. The proposed novel method utilizes a transformed linear simulation which is based on a Hermite transformation model where the transformation is chosen to be a monotonic cubic polynomial, calibrated such that the first four moments of the transformed model match the moments of the true process. This proposed novel method is utilized to predict the joint distributions of wave heights and periods of a sea state with the surface elevation data measured at the Gulfaks C platform in the North Sea, and the novel method's accuracy and efficiency are favorably validated by using comparisons with the results from an empirical joint distribution model, from a linear simulation model and from a second-order nonlinear simulation model.

• Structural Engineering and Mechanics
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• v.87 no.2
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• pp.165-172
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• 2023

This paper presents a novel method for modeling elastic wave propagation in long beams. The proposed method derives a solution for the transient transverse displacement of the beam's neutral axis without assuming the separation of variables (SV). By mapping the governing equation from the space domain to the frequency domain using Fourier transformation (FT), the transverse displacement function is determined as a convolution integral of external loading functions and a combination of trigonometric and Fresnel functions. This method determines the beam's response to general loading conditions as a linear combination of the analytical response of a beam subjected to an abrupt localized loading. The proposed solution method is verified through finite element analysis (FEA) and wave propagation patterns are derived for tone burst loading with specific frequency contents. The results demonstrate that the proposed solution method accurately models wave dispersion, reduces computational cost, and yields accurate results even for high-frequency loading.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.939-944
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• 1990

To recognize isomorphic transformation patterns, such as scale-change, translation and rotation transformed patterns, is an old difficult but interesting problem. Many researches have been done with a dominant approach of normalization by many eminent pioneers. However, there seems no a perfect system which can even recognize 90 .deg.-multiple rotation isomorphic transformation patterns for real needs. Here, as a new challenge, we propose a method of how to recognize 90 .deg.-multiple rotation isomorphic and symmetry isomorphic transformation patterns.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.3
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• pp.79-84
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• 1998

It is very difficult to analyze the transient temperature distribution during quenching of the steel because of coupled effects among temperature, structures and stresses. In this paper, using Inoue's equation of evolution and mixture rule, transient temperature distribution is calculated by the finite element method considering latent heat of transformation structure and temperature dependence of physical and mechanical prperties for the 0.45% carbon cylindrical steel bar with 40mm diameter and 20mm height during end-quenching.

• Journal of the korean Society of Automotive Engineers
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• v.6 no.4
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• pp.46-53
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• 1984

The analysis of temperature distribution and change of metallic structures during water quench were presented by finite element method. In temperature calculation the equation of unsteady state hear conduction problem considering latent heat due to phase transformation was applied to finite solid cylinder, SM 45C of 40mm diameter and 40mm height. In metallic structure analysis iso-thermal transformation curve and the equations of evolution in pearlite-martensite transformation were applied. The calculated results upon temperature and metallic structures were agreed with those of experimental observations.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.195.2-195.2
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• 2005

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.2 no.2
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• pp.83-95
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• 1990

It can be assumed that the ocean waves consist of many independent pure sinusoidal components which progress in arbitrary directions. To analyze irregular sea waves, both the spectrum method and the individual wave method have been used. The spectral approach is valid in the region where the water depth is deep and the linear property of velocity distribution is predominent, while the individual wave analysis method in the region where the water depth is shallow and the wave nonlinearity is significant. Therefore, to investigate the irregular wave transformation from the deep water to the shallow water region, it is necessary to relate the frequency spectrum which is estimated by the spectrum analysis method to the i oint probability distribution of wave height, period and direction affected by the boundary condition of the individual wave analysis method. It also becomes important to define the region where both methods can be applied. This study is a part of investigation to establish a systematic approach for analyzing the irregular wave transformation. The region where the spectral approach can be applied is discussed by earring out the experiments on the irregular wave transformation in the two-dimensional wave tank together with the numerical simulation. The applicability of the individual wave analysis method for predicting irregular wave transformation including wave shoaling and breaking and the relation between frequency spectrum and joint probability distribution of wave height and period are also investigated through the laboratory experiment and numerical simualtion.