• Korean Journal of Computational Design and Engineering
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• v.14 no.4
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• pp.261-270
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• 2009

We can save a lot of efforts and time to perform various kinds of multibody system dynamics simulations if the equations of motion of the multibody system can be formulated automatically. In general, the equations of motion are formulated based on Newton's $2^{nd}$law. And they can be transformed into the equations composed of independent variables by using velocity transformation matrix. In this paper the velocity transformation matrix is derived based on a topological modeling approach which considers the topology and the joint property of the multibody system. This approach is, then, used to formulate the equations of motion automatically and to implement a multibody system dynamics simulation program. To verify the the efficiency and convenience of the program, it is applied to the lifting simulation of a floating crane.

• Korean Journal of Mathematics
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• v.5 no.2
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• pp.169-176
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• 1997

The purpose of this note is to compare two known results related to the lifting problem of an action of a topological group G on a G-space X to a coverring space of X.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.864-867
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• 2005

In this paper we introduce a design of parallel architecture for wavelet transformation on FPGA. We implement wavelet transforms though lifting scheme and apply Daubechies4 transform equations. This technique has an advantage that we can obtain perfect reconstruction of the data. We divide our process to high pass filter and low pass filter. With this division, we can find coefficients from low and high pass filters simultaneously using parallel processing properties of FPGA to reduce processing time. From the equations, we have to design real number computation module, referred to IEEE754 standard. We choose 32 bit computation that is fine enough to reconstruct data. After that we arrange the real number module according to Daubechies4 transform though lifting scheme.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.11
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• pp.1040-1047
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• 2007

This paper presents ripple-free method that can occur in multirate controller design. The conventional multirate input controller has the problem that the ripple occurs in track-following because of chattering phenomenon in control input signal. In order to resolve the problem of rippling, it was proposed to eliminate the ripple phenomenon using feedforward compensator. This paper makes explains problems in conventional ripple-tree multirate controller and introduces a multirate controller design method applying lifting technique based on current estimators in condition space. Using the ripple-tree multirate controller, we show that chattering does not occur in the control input signal through applying the final value theorem from the viewpoint of discrete-time transformation. Also, this study proves that the ripple of the proposed controller decreases with the increase of this sampling frequency and, when sampling frequency is fixed, it decreases with the increase of the control input period.

• Journal of Information Processing Systems
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• v.14 no.5
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• pp.1293-1300
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• 2018

For the disadvantages of multi-scale geometric analysis methods such as loss of definition and complex selection of rules in image fusion, an improved multi-focus image fusion method is proposed. First, the initial fused image is quickly obtained based on the lifting stationary wavelet transform, and a simple normalized cut is performed on the initial fused image to obtain different segmented regions. Then, the original image is subjected to NSCT transformation and the absolute value of the high frequency component coefficient in each segmented region is calculated. At last, the region with the largest absolute value is selected as the postfusion region, and the fused multi-focus image is obtained by traversing each segment region. Numerical experiments show that the proposed algorithm can not only simplify the selection of fusion rules, but also overcome loss of definition and has validity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.1 s.244
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• pp.8-15
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• 2006

A Sparse Point Representation(SPR) based on interpolation wavelets is presented. The SPR is implemented for the purpose of CFD data compression. Unlike conventional wavelet transformation, the SPR relieves computing workload in the similar fashion of lifting scheme that includes splitting and prediction procedures in sequence. However, SPR skips update procedure that is major part of lifting scheme. Data compression can be achieved by proper thresholding method. The advantage of the SPR method is that, by keeping even point physical values, low frequency filtering procedure is omitted and its related unphysical thresholing mechanism can be avoided in reconstruction process. Extra singular feature detection algorithm is implemented for preserving singular features such as shock and vortices. Several numerical tests show the adequacy of SPR for the CFD data. It is also shown that it can be easily extended to nonlinear adaptive wavelets for enhanced feature capturing.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.7
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• pp.518-525
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• 2003

In this paper, we present a fast hardware architecture to implement a parallel 2-dimensional discrete wavelet transform(DWT)based on the lifting scheme DWT framework. The conventional 2-D DWT had a long initial and total latencies to get the final 2D transformed coefficients because the DWT used an entire input data set for the transformation and transformed sequentially The proposed architecture increased the parallel performance at computing the row directional transform using new data splitting method. And, we used the hardware resource sharing architecture for improving the total throughput of 2D DWT. Finally, we proposed a scheduling of hardware resource which is optimized to the proposed hardware architecture and splitting method. Due to the use of the proposed architecture, the parallel computing efficiency is increased. This architecture shows the initial and total latencies are improved by 50% and 66%.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.1
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• pp.1-9
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• 2009

In this paper, proposed digital image watermarking technique with lifting wavelet transformation. This watermark technique can be easily extended in video content fields. Therefore, we apply this watermark technique to layered depth image structure that is efficient compression method of multi-view video with depth images. This application steps are very simple, because watermark is inserted only reference image. And watermarks of the other view images borrow from reference image. Each view image of multi-view video may be guaranteed authentication and copyright.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.2
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• pp.57-69
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• 2000

A higher order panel method based on representation for both the geometry and the velocity potential is developed for the analysis of steady flow around marine propellers. The self-influence functions due to the normal dipole and the source are desingularized through the quadratic transformation, and then the singular part is integrated analytically whereas the non-singular part is integrated using Gaussian quadrature. A null pressure jump Kutta condition at the trailing edge is found to be effective in stabilizing the solution process and in predicting the correct solution. Numerical experiments indicate that the present method is robust and predicts the pressure distribution around lifting bodies with much fewer panels than existing low order panel methods.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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• pp.1590-1597
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• 1994

The aerodynamic analysis of a $6{\times}6$ counter-rotating propfan around a missile-like-body has been completed analytically using a frequency domain panel method. The present method requires Fourier transformation of flow field around the propfan in computing the velocities normal to the propfan lifting surfaces. The aerodynamic performance curve is determined by angle of attack and nonuniform inflow conditions. The inflow conditions result from the variations of missile flight speed, angle of attack, propfan location relative to control surfaces and control surface deflection angle. The two cases of propfan location relative to control surface, front and behind, are analyzed and the aerodynamic results are presented.