• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1641-1648
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• 2016

A weather radar estimates Doppler frequency and width of Doppler spectrum from the received weather signal which represents the return echoes from rain or dust particles in a corresponding area. These estimates are very important parameters since they are directly related to precipitation, wind velocity and degree of turbulence. Therefore, these estimated values should be highly reliable to obtain accurate weather information. However, the echoes of a weather radar include both the weather signal and the clutter which occurred from ground reflection or moving objects, etc. The existence of the clutter in the echoes may cause serious errors in the estimation of weather-related parameters. Therefore, in this paper, models are developed to represent the weather signal and the clutter for the purpose of analyzing estimation errors caused by the strong clutter echoes. Using these models, various return echoes according to the weather signal and clutter power are simulated to analyze the effects of the clutter.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.11
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• pp.655-662
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• 2003

In some volume visualization fields such as medical imaging, anisotropic volume data are more common than isotropic ones. In this paper, we propose an efficient rendering method for anisotropic volume data, which directly computes the intensity of intermediate samples by interpolating the intensity of two corresponding voxels on consecutive slices. Unlike density interpolation method, it does not require a preprocessing step for generating intermediate slices or additional memory for storing them. Additionally, we propose an adaptive intermediate voxel insertion method that avoids overblurring on object surfaces. This may occur when we render high frequency areas using the intensity interpolation method. Using these methods, we can improve the rendering speed without sacrificing image quality.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.5
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• pp.548-555
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• 2001

In this paper, we proposed a HVS(human visual system) model-based digital image watermarking which is not only invariant to rotation and translation but also more robust to lossy compression, cropping, and scaling as compared to the conventional method. Fourier transform and log-polar mapping is used to make the proposed algorithm invariant to rotation and translation, and in addition, watermark energy is embedded maximally based on spatial frequency sensitivity of HVS without the deterioration of the invisibility. As a result, the robustness of watermarking is improved both in general image processing operations such as cropping, low pass filtering, and lossy compression and in geometrical transforms such as rotation, translation, and scaling. And, by disjoint embedding of the watermark and the template without intersection, the deterioration of invisibility and robustness is prevented. Experimental results show that proposed watermarking is about 30~75 [%] more robust af compared to the conventional methods.

• Journal of Digital Contents Society
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• v.11 no.2
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• pp.235-242
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• 2010

Differently from instruments which synthesized sounds and tones in the past, voice synthesis engine for music production has reached to the level of creating music as if actual artists were singing. It uses the samples of human voices naturally connected to the different levels of phoneme within the frequency range. Voice synthesis engine is not simply limited to the music production but it is changing cultural paradigm through the second creations of new music type including character music concerts, media productions, albums, and mobile services. Currently, voice synthesis engine technology makes it possible that users input pitch, lyrics, and musical expression parameters through the score editor and they mix and connect voice samples brought from the database to sing. New music types derived from such a development of computer music has sparked a big impact culturally. Accordingly, this paper attempts to examine the specific case studies and the synthesis technologies for users to understand the voice synthesis engine more easily, and it will contribute to their variety of music production.

• Journal of Broadcast Engineering
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• v.3 no.1
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• pp.85-92
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• 1998

The block matching algorithm is the most popular motion estimation method in image sequence coding. In this paper, we propose a VLSI architecture. for implementing a recently proposed fast bolck matching algorith, which uses spatial correlation of motion vectors and hierarchical searching scheme. The proposed architecture consists of a basic searching unit based on a systolic array and two shift register arrays. And it covers a search range of -32~ +31. By using the basic searching unit repeatedly, it reduces the number of gatyes for implementation. For basic searching unit implementation, a proper systolic array can be selected among various conventional ones by trading-off between speed and hardware cost. In this paper, a structure is selected as the basic searching unit so that the hardware cost can be minimized. The proposed overall architecture is fast enough for low bit-rate applications (frame size of $352{\times}288$, 3Oframes/sec) and can be implemented by less than 20,000 gates. Moreover, by simply modifying the basic searching unit, the architecture can be used for the higher bit-rate application of the frame size of $720{\times}480$ and 30 frames/sec.

• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.6
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• pp.16-21
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• 1979

Two dimensional kernels which reconstruct a tomographic image from a blurred one formed by simple back-projection are investigated in the frequency domain and their performances are compared. The kernels are derived from a point spread function of the tomographic system and have the form of a ramp filter modified by several window functions to suppress ringings or artifacts in the reconstruction. Computer simulation using computer-generated phantom image data with different filter functions has been carried out. In this simulation, it is found that the computation time for 2-D reconstruction is much less than that of 1-D convolution method by a factor of ten or more whereas the reconstructed image quality of the former is far poorer than the latter. In 2-D reconstruction heavy windowing results in less noisy reconstruction but details smear out in this case. The trade-offs between these points are considered.

• Journal of the Korea Society of Computer and Information
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• v.16 no.10
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• pp.175-183
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• 2011

Performance of digital video watermarking is an assessment that hides a lot of information in digital videos. Therefore, it is required to find a way that enables to store lots of bits of data into a high quality video of the frequency area of digital contents. Hence, this paper designs a watermarking system improving security with an enhancing watermarking based on invisible watermarking and embedding an watermarking on LH and HL subband and its subband by transforming wavelet after the extraction of luminance component from the frames of video by compromising robustness and invisible of watermarking elements. The performance analysis of security of watermarking is carried out with a statistic method, and makes an assessment of robustness against variety of attacks to invisible watermarking. We can verify the security of watermarking against variety of attacks by testing robustness and invisible through carrying out general signal processing like noise addition, lossy compression, and Low-Pass filtering.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.970-976
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• 2007

This paper presents a novel polar transmitter architecture with a 2-bit sigma-delta modulator. In the proposed architecture, the 2-bit sigma-delta modulator is introduced to suppress quantization noise of conventional sigma-delta modulator. The power amplifier configuration is also modified in a binary form to accommodate the 2-bit digitized envelope signal. The Ptolemy simulation results of the proposed structure show that the spectral property is greatly improved in full transmit band of EDGE system. The fine quantization scheme of the 2-bit modulator lowers the noise level by 10dB without increasing the over-sampling ratio, which may be obtained if the over-sampling ratio increases twofold. Dynamic range is also enhanced up to 5dB owing to the new form of the power amplifier in the transmitter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.753-759
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• 2020

A modified Chebyshev lowpass filter function with progressively diminishing ripples in the passband is proposed and analyzed in the frequency domain. Owing to the diminishing ripples, the passband magnitude characteristic of the proposed Chebyshev function has improved compared to the classical Chebyshev function. In addition, the phase characteristics of the proposed Chebyshev function were improved considerably compared to that of the Chebyshev function, and the time delay of the proposed function was much simpler and flatter. In addition, the proposed Chebyshev filter was realizable by the passive doubly terminated ladder network delivering maximum power transfer for the order n, even or odd, thus making themselves amenable to low-sensitivity active RC or switched capacitor filters through the simulation techniques. To verify the proposed Chebyshev filter characteristics, a 6th order passive doubly terminated ladder lowpass filter was designed and analyzed using the MATLAB and SPICE program. Thus, the proposed Chebyshev function can remove the drawbacks of the classical Chebyshev function and could be applicable to the design of a filter with an improved filter size, phase, and time delay characteristics for various signal processing.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2380-2388
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• 2015

A hardware implementation of MOD(moving object detection) algorithm using EGML(effective Gaussian mixture learning)- based background subtraction to detect moving objects in video is described. Some approximations of EGML calculations are applied to reduce hardware complexity, and pipelining technique is adopted to improve operating speed. The MOD processor designed in Verilog-HDL has been verified by FPGA-in-the-loop verification using MATLAB/Simulink. The MOD processor has 2,218 slices on the Virtex5-XC5VSX95T FPGA device and its throughput is 102 MSamples/s at 102 MHz clock frequency. Evaluation results of the MOD processor for 12 images in the IEEE CDW-2012 dataset show that the average recall value is 0.7631, the average precision value is 0.7778 and the average F-measure value is 0.7535.