• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.4
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• pp.347-356
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• 1987

This paper is to propose a new line code suitable for a high speed unipolar pulse transmission system, such as a high speed optical digital transmission system. The original information speed can be converted into the transmission speed $\frac{(m+1)}{m}$ by the speed converter. Then this code, named mBiZ code, is generated by means of an Exclusive NOR between the bit stream inserted a space into every m bits and the bit stream delayed by the time slot allocated a single bit at the output coded sequence. Therefore, a mBiZ code can reduce a redundancy in the line code for transmission and its conversion circuits can be devised easily. The mBiZ code can also suppress undesirable long consecuitive identical digits and make line code balance in the mark and space ratio. Therefore, high frequency and low frequency components in power spectrum of a mBiZ code can be suppessed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2563-2578
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• 1996

In this paper, channel error characteristics are investigated to alleviate the channel error propagation problem of the digital TV transmission systems. First, error propagation problems, which are mainly caused by the inter-frame dependancy and variable length coding of the MPEG-2 baseline encoder, are intensively analyzed. Next, existing channel resilient schemes are systematically classified into two kinds of schemes; one for the encoder and the other for the decoder. By comparing the performance and implementation cost, the encoder side schemes, such as error localization, layered coding, error resilience bit stream generation techniques, are described in this paper. Also, in an effort to consider the parcticality of the real transmission situation, an efficient error detection scheme for a decoder system is proposed by employing a priori information of the bit stream syntas, checking the encoding conditions at the encoder stage, and exploiting the statistics of the image itself. Finally, subsequent error concealment technique based on the DCT coefficient recovery algorithm is adopted to evaluate the performance of the proposed error resilience technique. The computer simulation results show that the quality of the received image is significantly improved when the bit error rate is as high as 10$^{-5}$ .

• Journal of Broadcast Engineering
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• v.8 no.3
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• pp.259-267
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• 2003

In this paper, we propose a media processor to provide interactive services in mobile multimedia broadcasting environments. The proposed system Is designed to support various functionalities, such as generation of MPEG-4 IOD (Initial Object Descriptor)/OD(Object Descriptor)/BIFS (Binary Format for Scene) data, encapsulation of MPEG-4 AVC (Advanced Video Coding)/BSAC (Bit Sliced Arithmetic Coding) stream and generated IOD/OD/BIFS data into SL (Sync Layer) packet, packetization of SL packet into TS (Transport Stream) packet and multiplexing. The proposed media processor can provide MPEG-4 based interactive services for users.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.8
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• pp.1575-1580
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• 2012

In this paper, a DVB-T2(Digital Video Broadcasting-the 2nd Generation Terrestrial) receiver is designed under a USB-type windows environment, and the baseband frames for MPEG2-TS stream(File or Ethernet Modes) are analyzed for verifying the receiver. In addition, the performance of the BICM(Bit Interleaved Coding & Modulation) module in the receiver is analyzed in terms of PLP(Physical Layer Pipe) and L1(Layer 1) signals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2C
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• pp.315-323
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• 2004

In this paper we present a method to generate the bit stream of static video test patterns for testing the picture quality in DTV system. The proposed user-defined quantization table is suitable for the static video test pattern and for minimizing the deterioration of picture quality by quantization, the underflow or overflow of video buffer generated on the process of coding the static video test pattern is compensated by a adaptive zero stuffing algorithm so that optimal picture quality is implemented. Experimental result showed that the test pattern stream encoded by MPEG-2 software with the proposed algorithm had a stable bit rate and good video quality during the decoding process, which is about 3 dB higher than that of the conventional case.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.1
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• pp.59-65
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• 1999

In this paper, we design a entorpy encoder of HDTV/DTV encoder blocks on the basis of MPEG-II. The designed entropy encoder outputs its bit stream at 9Mbps bit rate inserting zero-stepping block to protect the depletion of buffer in case that the generated bit stream is stored in buffer and uses not only PROM bit combinational circuit to solve the problem of critical path, and packer block, one of submerge, is designed to packing into 24 bit unit using barrel shifter, and it is constructed to blocks of header information encoder, input information delay, submerge, and buffer control. Designed circuits is verified by VHDL function simulation, as a result of performing P&R with Gate compiler that apply $0.8{\mu}m$ Gate Array specification, pin and gate number of total circuits has been tested to each 235 and about 120,000.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7B
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• pp.628-637
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• 2003

This paper describes a novel multiplexing scheme for delay-sensitive multiple VBR-coded bit streams in live multimedia service offered to high-speed networks. The primary goal of multiplexing in this paper is to keep delay limits of each bit streams and to enhance network resource utilization when they no multiplexed and transmitted over network. For this aim, this paper presents a dynamical control scheme which does not cause violation of any delay constraints to each bit steam. The scheme is based on the assumption that recent behavior of the each bit scream has high correlation with near-term future behavior. Such property is used to make as flat as possible by both temporal averaging on a stream-by-stream and spatial averaging is introduced when multiple VBR-coded bit streams are multiplexed. The effectiveness of the scheme is evaluated by several simulation using an MPEG-coded video trace of Star_wars and it is shown that the proposed scheme can effectively reduce the feat rate md coefficient of variation of the multiplexed transmission rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2207-2216
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• 2012

Recently, wireless Internet environment with mobile phones and wireless sensor networks with severe resource restrictions have been actively studied. Moreover, an overall security issues are essential to build a reliable and secure sensor network. One of secure solution is to develop a fast cryptographic algorithm for data encryption. Therefore, we propose a 128-bit stream cipher, AA128 which has efficient implementation of software and hardware and is suitable for real-time applications such as wireless Internet environment with mobile phones, wireless sensor networks and Digital Right Management (DRM). AA128 is stream cipher which consists of 278-bit ASR and non-linear transformation. Non-linear transformation consists of Confusion Function, Nonlinear transformation(SF0 ~ SF3) and Whitening. We show that the proposed stream cipher AA128 is faster than AES and Salsa20, and it satisfies the appropriate security requirements. Our hardware simulation result indicates that the proposed cipher algorithm can satisfy the speed requirements of real-time processing applications.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.2
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• pp.41-47
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• 2008

Most of media compression CODECs adopts the variable length coding method. This paper proposes special registers and instruction set for bit stream process in order to accelerate the decoding process of the variable length code. The instruction set shares the conventional data path to minimize additional costs. And bit stream is read from the memory instead of the special port. Therefore the instruction set minimizes the change of the processor, and is adopted without any additional input controller and buffer, and accelerate decoding process of variable length code. The data path of the instruction set needs additional 65 bits memory and 344 equivalent gates, 0.19 ns delay under TSMC $0.25{\mu}m$ technology. The instruction set reduced the execution time of the variable length code decoding process in H.264/AVC by about 55%.

• The Pure and Applied Mathematics
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• v.11 no.1
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• pp.1-14
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• 2004

Due to the development of computer network and mobile communications, the security in image data and other related source are very important as in saving or transferring the commercial documents, medical data, and every private picture. Nonetheless, the conventional encryption algorithms are usually focusing on the word message. These methods are too complicated or complex in the respect of image data because they have much more amounts of information to represent. In this sense, we proposed an efficient secret symmetric stream type encryption algorithm which is based on Boolean matrix operation and the characteristic of image data.