• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.10
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• pp.51-60
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• 1999

For an effective phase-multiplexing in holographic memory system, four types of phase code used as reference beam are generated. In case of $32 {\times} 32$ address beam, a phase error with 0%, 5%, 10% 15%, 20%, and 25% error rate, is purposely added to the real phase values in order to consider the practical SLM's nonlinear characteristics of phase modulation in computer simulation, cross talks and SNRs are comparatively analysed for these phase-codes by the auto and cross-correlation. Pseudo-Random(PSR) Phase Code has the lowest cross-correlation mean value of 0.067 among four types of Phase Code, which means the SNR of the PSR is higher than other Phase Codes. Also, the standard deviation of the PSR phase code indicating the degree of recalled data degradation is the lowest value of 0.0113.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1C
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• pp.1-8
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• 2003

In this paper, performance of the CPC(complex phase code) which is recently proposed as a practical phase encoding method for phase-code multiplexes holographic memory system is comparatively analyzed with those of the conventional phase codes such as PR(pure random code), RCE(random code with equality), WHM(Walsh Hadamard Matrix). In computer simulation, the size of an address bean is fixed at 32$\times$32 pixels and 0%-25% phase-error ratio in a pixel are intentionally added to the real phase values to consider the nonlinear phase-modulation characteristics of the practical spatial light modulator. From comparative analysis of crosstalks and signal-to-noise ratios for these phase codes by calculating auto-correlation and cross-correlation, it is found that the CPC have the lowest cross-correlation mean value of 0.021, the lowest standard deviation of 0.0113 and the highest signal-to-noise ratio(SNR) of 27.4 among the four types of phase code. In addition, from the calculation of the number of all possible address beams for these four types of phase code as the size of the address beam is fixed to 3232 pixels, the CPC is found to have 6.334$\times$10$^{49}$ address beams, which are relatively higher number than that of the conventional phase codes.

• Journal of Broadcast Engineering
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• v.25 no.5
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• pp.655-664
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• 2020

Free viewpoint image synthesis technology is one of the important technologies in the MPEG-I (Immersive) standard. RVS (Reference View Synthesizer) developed by MPEG-I and in use in MPEG group is a DIBR (Depth Information-Based Rendering) program that generates an image at a virtual (intermediate) viewpoint from multiple viewpoints' inputs. RVS uses the mesh surface method based on computer graphics, and outperforms the pixel-based ones by 2.5dB or more compared to the previous pixel method. Even though its OpenGL version provides 10 times speed up over the non OpenGL based one, it still shows a non-real-time processing speed, i.e., 0.75 fps on the two 2k resolution input images. In this paper, we analyze the internal of RVS implementation and modify its structure, achieving 34 times speed up, therefore, real-time performance (22-26 fps), through the 3 key improvements: 1) the reuse of OpenGL buffers and texture objects 2) the parallelization of file I/O and OpenGL execution 3) the parallelization of GPU shader program and buffer transfer.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.8
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• pp.245-250
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• 2014

In recent years, the developments of medical technology and emergency medical services have been changed to home from the hospital. In this regard, the researches for the prevention or early diagnosis have become actively. In particular, bio-signal monitoring is applied to a variety of u-healthcare application services. The proposed system in this paper is to provide a security technology to protect the medical information measured from the various sensors. Especially, bio-signal information is privacy-sensitive personal information that must be protected. We applied a two-dimensional code technology, QR code, for the protection and management. In the client side, it can analyze the QR code and confirm the results on devices. Finally, with this proposed platform, we show the results of application service to verify the creation and distribution of integrated image file between the bio-signal and medical image information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1203-1212
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• 1994

This paper proposes a variable block size vector quantization based on a biorthogonal wavelet transform for image compression. An image is first decomposed with the biorthogonal wavelet transform into multiresolution image and the wavelet coefficients of the middle frequency bands are segmented using the quadtree sturcture to extract the perceptually important regions in the middle frequency bands. A sedges of middle frequency bands exist the corresponding position of high frequency bands, the complicated quadtree structure of middle frequency bands is equally applied to the high frequency bands. Therefore the overhaed information of the quadtree codes needed to segment the high frequency bands can be reduced. The segmented subblocks are encoded with the codebook designed at the each scales and directions. The simulation results showed that the proposed methods could reproduce higher quality image with bit rate reduced about 20(%) than of the preceding VQ method and sufficiently reduce the bolck effect and the edge degradation.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.01a
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• pp.63-64
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• 2012

본 논문은 보다 유연하고 추상적인 데이터를 사용자에게 전달하여 스스로가 물체를 인지하고 느낄 수 있도록 하는 공감각 현상에 대하여 연구하고 이 연구 결과를 응용하도록 한다. 오픈소스인 ReacTable을 이용하여 일종의 TAG 역할을 하는 특징적 그림을 명세코드화 한다. 그리고 이를 실제 숫자나 문자 혹은 객체 인식에 응용하도록 한다. 그리하여 시각적인 정보 없이 객체를 인식하고 사용할 수 있는 일상적인 생활이 가능하도록 하였다. 또한 가격이 이용가능성이 많으며 이동성과 휴대성을 동시에 고려한 ZigBee 무선 영상통신 기술을 통하여 영상을 서버나 휴대용단말기에 전송하는 방법을 사용하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.145-148
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• 2011

본 논문은 사용자에게 유연하고 추상적인 데이터를 전달하여 사용자 스스로가 물체를 인지하고 '느낄' 수 있도록 공감각 현상에 대한 연구결과를 응용하다. 또한, 오픈소스(ReacTable)를 사용하여 일종의 TAG 역할을 하는 특징적 그림을 명세코드화한 후 이를 실제 숫자나 문자 혹은 객체 인식에 응용하여 시각적인 정보 없이 객체를 인식하고 사용할 수 있는 일상적인 생활이 가능하도록 하였다. 덧붙여 이동성과 휴대성을 고려함과 동시에 저렴하고 이용가능성이 많은 ZigBee 무선 영상통신 기술을 통하여 처리하고자 하는 영상을 실내의 서버나 휴대용단말기에 전송하는 방법을 사용하였다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.58-66
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• 2009

Recently the emerging demands of the light-video encoder promotes lots of research efforts on DVC (Distributed Video Coding). As an appropriate video compression method, DVC has been studied, and Wyner-Ziv (WZ) video compression is its one representative structure. The WZ encoder splits the image into two kinds of frames, one is key frame which is compressed by conventional intra coding, and the other is WZ frame which is encoded by WZ coding. The WZ decoder decodes the key frame first, and estimates the WZ frame using temporal correlation between key frames. Estimated WZ frame (Side Information) cannot be the same as the original WZ frame due to the absence of the WZ frame information at decoder. As a result, the difference between the estimated and original WZ frames are regarded as virtual channel noise. The WZ frame is reconstructed by removing noise in side information. Therefore precise noise estimation produces good performance gain in WZ video compression by improving error correcting capability by channel code. But noise cannot be estimated precisely at WZ decoder unless there is good WZ frame information, and generally it is estimated from the difference of corresponding key frames. Also the estimated noise is limited by comparing with frame level noise to reduce the uncertainty of the estimation method. However these methods cannot provide good noise estimation for every frame or each bit plane. In this paper, we propose a noise nodel selection method which chooses a better noise model for each bit plane after generating candidate noise models. Experimental result shows PSNR gain up to 0.8 dB.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.10
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• pp.429-440
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• 2014

The iris recognition is a biometrics technology to extract and code an unique iris feature from human eye image. Also, it includes the technology to compare with other's various iris stored in the system. On the other hand, eyelashes in iris image are a external factor to affect to recognition rate of iris. If eyelashes are not removed exactly from iris area, there are two false recognitions that recognize eyelashes to iris features or iris features to eyelashes. Eventually, these false recognitions bring out a lot of loss in iris informations. In this paper, in order to solve that problems, we removed eyelashes by gabor filter that using for analysis of frequency feature and improve preservation rate of iris informations. By novel method to extract various features on iris area using angle, frequency, and gaussian parameter on gabor filter that is one of the filters for analysing frequency feature for an image, we could remove accurately eyelashes with various lengths and shapes. As the result, proposed method represents that improve about 4% than previous methods using GMM or histogram analysis in iris preservation rate.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.13-18
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• 1998

The practical use of the particle image velocimetry(PIV), a whole-field velocity measurement method, requires the use of fast, reliable, computer-based methods for tracking velocity vectors. The full search block matching, the most widely studied and applied technique both in area of PIV and Image Coding and Compression, is computationally costly. Many less expensive alternatives have been proposed mostly in the area of Image Coding and Compression. Among others, TSS, NTSS, HPM are introduced for the past PIV analysis, and found to be successful. But, these algorithms are based on small dynamic range, 7 pixels/frame in maximum displacement. To analyze the images with large displacement, Even and Odd field image separation and a simple version of multi-resolution hierarchical procedures are introduced in this paper. Comparison with other algorithms are summarized. A Results of application to the turbulent backward step flow shows the improvement of new algorithm.