• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.5C
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• pp.716-725
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• 2004

In this paper, a new multiview stereoscopic 3D display system using a VHLS(volume holographic lenticular sheet) is suggested. The VHLS, which acts just like an optical direction modulator, can be implemented by recording the diffraction gratings corresponding each directional vector of the multiview stereoscopic images in the holographic recording material by using the angularly multiplexed recording property of the conventional volume hologram. Then, this fabricated VHLS is attached to the panel of a LCD spatial light modulator and used to diffract each of the multiview image loaded in a SLM to the corresponding spatial direction for making a 3D stereo view-zone. Accordingly, in this paper, the operational principle and characteristics of the VHLS are analyzed and an optimized 4-view VHLS is fabricated by using a commercial photopolymer. Then, a new VHLS-based 4-view stereoscopic 3D display system is implemented. Through some experimental results using a 4-view image synthesized with adaptive disparity estimation algorithm, it is suggested that implementation of a new VHLS-based multiview stereoscopic 3D display system can be possible.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.85-92
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• 2009

This paper proposes a full-search block-matching motion estimation circuit with hybrid architecture combining systolic arrays and adder trees for an MPEG-4 encoder. The proposed circuit uses systolic arrays for motion estimation with a small number of clock cycles and adder trees to reduce required circuit resources. The interpolation circuit for 1/2 pixel motion estimation consists of six adders, four subtracters and ten registers. We improved the circuit performance by resource sharing and efficient scheduling techniques. We described the motion estimation circuit for integer and 1/2 pixels at RTL in Verilog HDL. The logic-level circuit synthesized by using 130nm standard cell library contains 218,257 gates and can process 94 D1($720{\times}480$) image frames per second.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.34-41
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• 1999

Unlike the traditional radar system, Synthetic Aperture Radar(SAR) system is capable of imaging a target scene to ceertain degree of cross-range resolution. And this resolution is mainly depends on the size of aperture synthesized. Thus, a good system model and inversion scheme should be developed to actually give effect of synthesizing aperture size, which in turn gives better cross range resolution of reconstructed target scene. Among several inversion schemes for SAR imaging, we used an inversion scheme called wavefront reconstruction which has no approximation in wave propagation analysis, and tried to verify whether the collected data with synthesized aperture actually give the same support as that with physical aperture in the same size. To do this, we performed a signal subspace comparison of two imaging models with physical and synthesized arrays, respectively. Theoretical comparisons and numerical analysis using Gram-Schmidt procedures have been performed. The results showed that the synthesized array data fully span the physical array data with the same system geometry. This result strongly supports the previously proposed inversion scheme valuable in high resolution radar imaging.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.9
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• pp.722-730
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• 2018

This paper presents an analysis technique for estimating the properties of a target's power-spill patterns observed in reconstructed SAR images, which in turn depend on the setup squint angle of the FMCW signal-based SAR system. The target responses observed in the reconstructed SAR images were affected by the range-direction and azimuth-direction of a wave projected on the ground, and the obtained results were analyzed by applying three-dimensional squinted SAR geometry. Furthermore, the rotation patterns were verified through simulations based on the FMCW signal model and back-projection algorithm. This paper summarizes the obtained evaluation results as a function of SAR geometry and squint angle.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.5
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• pp.299-306
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• 2015

A conventional phased array system can control an ultrasonic beam electronically by adjusting the excitation time delay of individual elements in a multi-element probe and produce an ultrasonic image. In Contrast, full matrix capture (FMC) is a data acquisition process that allows receiving ultrasonic signals from one single shot of the phased array transducer element through all the other elements and captures the complete dataset from every possible transmit-receive combination. This FMC data can be used to create the ultrasonic image in post processing. It is possible to produce not only images equivalent to conventional phased array image but also total focusing method (TFM) images with improved resolution and sharpness, which is virtually focused at any point in a region of interest. In this paper, the system that can perform FMC by using a conventional phased array instrument is developed, and a study was conducted on the imaging algorithms to reconstruct sector B-scan and TFM images from FMC dataset.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.5
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• pp.357-364
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• 2003

The main difficulty in estimating the fundamental matrix stems from the unavoidable outliers inherent in the given correspondence matches. Several researches showed that the estimation results are much dependent on selecting the corresponding points. These represent that it is important to solve the problems due to errors on the point locations and mismatches. In this paper, our analysis shows that if the evenly distributed corresponding points are selected, we can estimate a more precise fundamental matrix. This paper presents novel approaches to estimate the fundamental matrix by considering the inlier distributions. In order to select evenly distributed points, we divide the entire image into the subregions, and then examine the number of the inliers in each subregion and the area of each region. The simulation results showed that our consideration of the inlier distribution can provide a more precise estimation of the fundamental matrix.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.6
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• pp.141-148
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• 2003

This paper proposes a new algorithm that generates the smooth and realistic transition views from one viewpoint to another on the multi-panorama based navigation system. The proposed algorithm is composed of two steps. One is prewarping that aligns the viewing directions of two panoramic images, and the other is the bidirectional disparity morphing(BDM) that generates the intermediate scene from the aligned panoramic images. For prewarping, we compute the phase correlation between two images in order to obtain the information, such as translation, rotation, and scaling. Then we align the viewing directions of two original images using these information. Afterprewarping, we compute the block based disparity vector(DV) and smooth them using two occluding patterns. As we apply these DVs to the BDM, we can generate the elaborate intermediate scene. We make an experiment on the proposed algorithm with some real panoramic images and obtain good quality intermediate scenes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.2
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• pp.127-138
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• 2007

In this paper, we propose a new X-masking scheme for utilizing logic built-in self-test The new scheme exploits the phase-shifting network which is based on the shift-and-add property of maximum length pseudorandom binary sequences(m-sequences). The phase-shifting network generates mask-patterns to multiple scan chains by appropriately shifting the m-sequence of an LFSR. The number of shifts required to generate each scan chain mask pattern can be dynamically reconfigured during a test session. An iterative simulation procedure to synthesize the phase-shifting network is proposed. Because the number of candidates for phase-shifting that can generate a scan chain mask pattern are very large, the proposed X-masking scheme reduce the hardware overhead efficiently. Experimental results demonstrate that the proposed X-masking technique requires less storage and hardware overhead with the conventional methods.

• Journal of the Korean Geophysical Society
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• v.4 no.2
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• pp.113-120
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• 2001

The discrete wavelet transform(DWT) has potential as a tool for supplying discriminatory attributes with which to distinguish seismic events. The wavelet transform has the great advantage over the Fourier transform in being able to localize changes. In this study, a discrete wavelet transform is applied to seismic traces for identifying seismic events and picking of arrival times for first breaks and S-wave arrivals. The precise determination of arrival times can greatly improve the quality of a number of geophysical studies, such as velocity analysis, refraction seismic survey, seismic tomography, down-hole and cross-hole survey, and sonic logging, etc. provide precise determination of seismic velocities. Tests for picking of P- and S- wave arrival times with the wavelet transform method is conducted with synthetic seismic traces which have or do not have noises. The results show that this picking algorithm can be successfully applied to noisy traces. The first arrival can be precisely determined with the field data, too.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.6 s.336
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• pp.39-48
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• 2005

This paper proposes a reconfigurable coprocessor for communication systems, which can perform high speed computations and various functions. The proposed reconfigurable coprocessor can easily implement communication operations, such as scrambling, interleaving, convolutional encoding, Viterbi decoding, FFT, etc. The proposed architecture has been modeled by VHDL and synthesized using the SEC 0.18$\mu$m standard cell library. The gate count is about 35,000 gates and the critical path is 3.84ns. The proposed coprocessor can reduced about $33\%$ for FFT operations and complex MAC, $37\%$ for Viterbi operations, and $48\%\~84\%$ for scrambling and convolutional encoding for the IEEE 802.11a WLAN standard compared with existing DSPs. The proposed coprocessor shows Performance improvements compared with existing DSP chips for communication algorithms.