• The Journal of the Acoustical Society of Korea
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• v.18 no.1
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• pp.72-77
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• 1999

In this paper, we propose a wavelet VQ approach to modeling VBR broadcast video traffic. The proposed method decomposes video traffic into two parts via wavelet transformation, and models each part separately. The first part, which is modeled by an AR(1) process, serves to capture the long-term trend of the traffic; the second part, classified via vector quantization, addresses the short-term behavior of the traffic. Compared with other VBR video models, our model has three advantages. First, it allows the separate modeling of long- and short-term behavior of the video traffic; second, it preserves the periodic coding structure in traffic data; and third, it provides an unified approach for the frameand slice-level traffic modeling. We demonstrate the validity of our model by statistical measurements and network performance simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3C
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• pp.133-140
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• 2005

This paper introduces a spatial error concealment technique using directional interpolation in block-based compression. The first step involves finding the spatial direction vectors represented an edge-direction in the lost block using spatial boundary matching algorithm. Then, the error blocks are recovered by directional interpolation through these vectors and concealed by using the recovered blocks which have lower directional boundary matching error out of them relatively. This proposed method is able to deal with errors on macroblock or slice level adaptively. And it has lower complexity and maintains better performance compared to the conventional methods.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.38-41
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• 2011

최근 HD급 이상의 해상도를 가지는 영상을 위한 차세대 코덱 표준이 연구되고 있다. 이 코덱의 특징은 압축효율을 증가시키기 위해서 시간을 많이 소모시키는 복잡한 툴들을 많이 채택하고 있다는 점이다. 이는 실시간 방송에 대한 부담감으로 작용되기 때문에, 표준을 재정하는 전문가들은 속도 개선을 위한 병렬화 연구 또한 동시에 진행을 하고 있다. 병렬화 방법 중 슬라이스 단위 병렬화와 모듈 내부 병렬화가 대표적으로 논의되고 있지만, 이 두 가지 방법은 각각 시간 지연과 추가 비트 할당이라는 단점이 있기 때문에 이를 극복하기 위한 새로운 병렬화 기법이 요구되고 있다. 본 논문에서는 시간 지연과 추가비트 할당을 극복 가능한 병렬화 기법을 연구하였는데, HEVC 코덱의 구조 분석을 통해 어떻게 병렬화 해야 단점을 극복할 수 있는지 알아보고 단점을 극복한 병렬화 기법이 속도 개선을 할 수 있는지 시간 분석을 통해 알아본다. 본 논문에서는 구조 분석을 통해 알아낸 CU 단위 병렬화 기법을 제안하고 CU 단위 병렬화 기법을 HEVC Test model reference software 2.1 decoder에 적용하여 Full HD 영상에 대해 Lowdelay에서 평균 19.83%의 속도 개선을 얻었으며, Randomaccess에서 평균 22.63%의 속도 개선을 얻었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.46-48
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• 2011

기존의 참조 소프트웨어인 MPEG-2, MPEG-4, H.264/AVC에서는 움직임 벡터를 찾을 때 항상 고정된 해상도를 사용하였으며 다른 참조 소프트웨어인 KTA에서는 움직임 벡터를 찾을 때 움직임벡터의 해상도를 슬라이스 단위로 성능이 가장 높은 해상도를 선택해서 사용하였다. 하지만 움직임 벡터의 해상도는 블록마다 서로 다르기 때문에 블록별로 서로 다른 해상도를 적응적으로 사용할 필요가 있다. 적응적인 움직임 벡터 해상도 부호화 방법은 이러한 점을 이용하여 블록 별로 현재 블록의 움직임 벡터가 1/4 해상도인지 1/8 해상도인지에 판단하고 그에 대한 정보를 복호기에 전송해준다. 제안하는 알고리즘은 적응적 움직임 벡터 해상도를 사용하여 부호화 할 때 1/8 해상도 움직임 벡터가 성능이 없다고 판단되는 곳에선 적응적 움직임 벡터 해상도 방식을 사용하지 않고 1/4 해상도로만 움직임 벡터를 찾는다. 이러한 경우 해상도 정보를 복호기에 전송하지 않아 부호화 효율을 높일 수 있고 또한 1/8 해상도에 대한 움직임 예측을 하지 않기 때문에 부호화기 복잡도를 낮출 수 있다. 실험결과 평균 0.2%의 성능을 얻을 수 있었으며 부호화기 복잡도는 4% 감소하였다.

• Nuclear Engineering and Technology
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• v.27 no.1
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• pp.1-7
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• 1995

The mechanism of radionuclide colloid transport in porous media was studied through modeling and experiment. A nondestructive column scanning system was developed to improve the traditional destructive core slicing method. With an aid of this system we could get much more results from one experiment. Neutron activated clay soaked with soluble isotopes was used as colloid suspension. Filtration coefficients obtained through the experiments show two families of colloids despite their size distribution. New modeling of polydispersed colloid transport was made with two lumped parameters. This new model simulates well. Among the soluble isotopes $^{l37}$Cs mowed mainly as a form of colloid, but $^{85}$ Sr did not.t.

• Journal of Biomedical Engineering Research
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• v.20 no.3
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• pp.265-274
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• 1999

In this paper, we propose a novel interframe coding algorithm especially appropriate for 3-D medical images. The proposed algorithm is based on a video coding algorithm using motion estimation/ compensation and transform coding. In the algorithm, warping is adopted lor motion compensation (MC). Then, by using adaptive mode selection, a motion compensated residual image and original image are mixed up in the wavelet transform domain for improvement in coding performance. The mixed image is then compressed by the zerotree coding method. We prove that the adaptive mode selection technique in the wavelet transform domain is very useful lor 3-D medical image coding. Simulation results show that the proposed scheme provides good performance regardless of inter-slice distance and is prospective for 3-D medical image compression.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.187-189
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• 2018

In this paper, the optimal design conditions for hardware implementation of the Secure Hash Algorithm3-512 (SHA3-512) hash function were analyzed. Five SHA3-512 hash cores with data-path of 64-bit, 320-bit, 640-bit, 960-bit, and 1600-bit were designed, and their functionality were verified by RTL simulation. Based on the results synthesized with Xilinx Virtex-5 FPGA device, we evaluated the performance of the SHA3-512 hash cores, including maximum frequency, throughput, and occupied slices. The analysis results show that the best hardware performance of SHA3-512 hash core can be achieved by designing it with 1600-bit data-path.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5C
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• pp.487-495
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• 2007

When error occurs during the network transmission of the image, the quality of the restored image is very serious. Therefore to maintain the received image quality, the error concealment technique is necessary. This paper presents an efficient spatial error concealment method using adaptive edge-oriented interpolation. It deals with errors on slice level. The proposed method uses boundary matching method having 2-step processes. We divide error block into external and internal region, adaptively restore each region. Because this method use overall as well as local edge characteristics, it preserves edge continuity and texture feature. The proposed technique reduces the complexity and provide better reconstruction quality for damaged images than the previous methods.

• Journal of the Korea Furniture Society
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• v.22 no.4
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• pp.270-277
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• 2011

This study aims to find new solutions to the problem of utilization of materials and techniques represented in the development of modern lighting design. LED is an important component in modern lighting design and pine tree is one of the most popular domestic wood in furniture design in Korea. In this study, design is developed into various types of furniture such as a table, a chest, and a lighting, by researching manufacturing process and examining the use of slicing pine tree. The technique of slicing pine tree is a simple linear arrangement that was traditionally used in wooden furniture in Lee dynasty, with an emphasis on repetitive rhythm. The slicing technology is used to expand the usage of domestic pine tree. The beauty of natural wood is expressed with the transmission of light by applying this technique to the lighting design. It also brings new communication in between artificial lighting and natural wood combining this traditional technique and LED lighting in design. Finally, this study suggests particular value through the convergence of analog and digital by using the traditional wooden technique that keeps natural wood prints and new digital technology by using LED lighting. More discussions and research about this subject are expected continuously through this study.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.25-33
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• 2008

Video telephony is a representative service in 3G mobile network. And there have been efforts to improve quality of video telephony service in different fields. In Korea, the leading mobile service provider SKTelecom and KTF service the WCDMA network as 3G mobile network. Now, more than a million people is using the network. In this paper, we study about video telephony over WCDMA network. and propose error minimizing algorithm using cross-layer adaptation between physical layer and video codec. We simulated 3G-324M protocol with MPEG-4 video codec, and simulation results show suggested algorithm improve packet transmission rate for improving quality of video telephony service.