• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.360-363
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• 1999

Video data compression is a major key technology in the field of multimedia applications. Variable-length coding is the most popular data compression technique which has been used in many data compression standards, such as JPEG, MPEG and image data compression standards, etc. In this paper, we present memory efficient VLC decoder architecture for MPEG-2 application which can achieve small memory space and higher throughput. To reduce the memory size, we propose a new grouping, remainder generation method and merged lookup table (LUT) for variable length decoders (VLD's). In the MPEG-2, the discrete cosine transform (DCT) coefficient table zero and one are mapped onto one memory whose space requirement has been minimized by using efficient memory mapping strategy The proposed memory size is only 256 words in spite of mapping two DCT coefficient tables.

• Journal of the Korean Society of Safety
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• v.24 no.5
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• pp.1-5
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• 2009

NiTiCu alloys can produce a large force per unit volume and operate with a simple mechanism. For this reasons, it has been widely studied for application as a micro actuator. So in this study, one-way and two way shape memory effects of Ti-42.5at%Ni-2.0at%Cu alloys are studied. In the case of one-way shape memory effects, shape memory recoverable stress and strain of this alloys were measured by means of tension and compression tests under constant temperature. The strains by tension and compression stress were perfectly recovered by heating at any testing conditions also shape memory recoverable stress increased to 116 MPa in tension tests and to 260 MPa in compression tests. In the case of two-way shape memory effects, transformation temperatures from thermal cycling under constant uniaxial applied tension and compression loads linearly increased by increasing external loads and their maximum recoverable strain is 3.8% at 100MPa tensile condition and 2.2% at 125 MPa compression condition.

• The KIPS Transactions:PartA
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• v.11A no.3
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• pp.157-162
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• 2004

This paper suggests the CAMD(Compression Algorithm for in-Memory Data) algorithm that is not moved the pages into the swap space by assigning the compressed cache area in the main memory. The CAMD algorithm that supports the virtual memory system takes high memory usability and performance benefit by reducing the page fault. The memory data is not general data. It is extraordinary data format. In general it consists of specific form of data. Therefore. the CAMD algorithm can compress this data efficiently.

• Journal of Korea Multimedia Society
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• v.14 no.1
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• pp.94-102
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• 2011

To alleviate the size and bandwidth requirement in JPEG2000 system, a new Embedded Compression(EC) algorithm with minor image quality drop is proposed. For both random accessibility and low latency, very simple and efficient hadamard transform based compression algorithm is devised. We reduced LL intermediate memory and code-block memory to about half size and achieved significant memory bandwidth reductions(about 52~73%) through proposed multi-mode algorithms, without requiring any modification in JPEG2000 standard algorithm.

• The KIPS Transactions:PartA
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• v.15A no.5
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• pp.269-274
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• 2008

Recently, lots of embedded processors which can run streaming multimedia with high resolution display are introduced. Among the applications running on these embedded processors, real-time audio streaming is one of the applications that suffer from the lack of energy and memory space. In this paper, we propose a novel data compression method on scratch-pad memory, which saves both useful space on the scratch-pad memory and energy. We have implemented the data compression scheme on the GDM1202 real-time audio streaming processor, and the performance results show that we obtained 13.3% energy saving while maintaining comparable application performance to that of the non-compression case.

• The KIPS Transactions:PartA
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• v.9A no.4
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• pp.405-412
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• 2002

The embedded system has less fast CPU and lower memory than PC(personal Computer) or Workstation system. Therefore embedded operating is system is designed to efficiently use the limited resource in the system. Virtual memory management or the embedded linux have a low efficiency when page fault is occurred to get a data from I/O device. Because a data is moving from the swap device to main memory. This paper suggests virtual memory compression algorithm for improving in virtual memory management and capacity of space. In this paper, we present a way to performance implement a virtual memory compression system that achieves significant improvement for the embedded system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.20-25
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• 2016

This study addresses a low complexity and lossless frame memory compression algorithm based on block-buffer structure for efficient high resolution video processing. Our study utilizes the block-based MHT (modified Hadamard transform) for spatial decorrelation and AGR (adaptive Golomb-Rice) coding as an entropy encoding stage to achieve lossless image compression with low complexity and efficient hardware implementation. The MHT contains only adders and 1-bit shift operators. As a result of AGR not requiring additional memory space and memory access operations, AGR is effective for low complexity development. Comprehensive experiments and computational complexity analysis demonstrate that the proposed algorithm accomplishes superior compression performance relative to existing methods, and can be applied to hardware devices without image quality degradation as well as negligible modification of the existing codec structure. Moreover, the proposed method does not require the memory access operation, and thus it can reduce costs for hardware implementation and can be useful for processing high resolution video over Full HD.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.4
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• pp.177-185
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• 2005

NAND-type flash memory is becoming increasingly popular as a large data storage for mobile computing devices. Since flash memory is an order of magnitude more expensive than magnetic disks, data compression can be effectively used in managing flash memory based storage systems. However, compressed data management in NAND-type flash memory is challenging because it supports only page-based I/Os. For example, when the size of compressed data is smaller than the page size. internal fragmentation occurs and this degrades the effectiveness of compression seriously. In this paper, we present an efficient flash compression layer (FCL) for NAND-type flash memory which stores several small compressed pages into one physical page by using a write buffer Based on prototype implementation and simulation studies, we show that the proposed scheme offers the storage of flash memory more than $140\%$ of its original size and expands the write bandwidth significantly.

• Journal of Broadcast Engineering
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• v.16 no.2
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• pp.339-349
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• 2011

IBDI (Internal Bit Depth Increase) is able to significantly improve the coding efficiency of high definition video compression by increasing the bit depth (or precision) of internal arithmetic operation. However the scheme also increases required internal memory for storing decoded reference frames and this can be significant for higher definition of video contents. So, the reference frame memory compression method is proposed to reduce such internal memory requirement. The reference memory compression is performed on 4x4 block called the processing unit to compress the decoded image using the correlation of nearby pixel values. This method has successively reduced the reference frame memory while preserving the coding efficiency of IBDI. However, additional information of each processing unit has to be stored also in internal memory, the amount of additional information could be a limitation of the effectiveness of memory compression scheme. To relax this limitation of previous memory compression scheme, we propose a selective merging-based reference frame memory compression algorithm, dramatically reducing the amount of additional information. Simulation results show that the proposed algorithm provides much smaller overhead than that of the previous algorithm while keeping the coding efficiency of IBDI.

• Journal of KIISE:Software and Applications
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• v.37 no.11
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• pp.851-858
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• 2010

Most mobile devices use a NAND flash memory as their secondary memory. A compressed code of the firmware is stored in the NAND flash memory of mobile devices in order to reduce the size and the loading time of the firmware from the NAND flash memory to a main memory. In order to use a demand paging properly, a compressed code should be decompressed very quickly. The thesis introduces a new dictionary based compression algorithm for the fast decompression. The introduced compression algorithm uses a different method with the current LZ method by storing the "exclusive or" value of the two instructions when the instruction for compression is not equal to the referenced instruction. Therefore, the thesis introduces a new compression format that minimizes the bit operation in order to improve the speed of decompression. The experimental results show that the decoding time is reduced up to 5 times and the compression ratio is improved up to 4% compared to the zlib. Moreover, the proposed compression method with the fast decoding time leads to 10-20% speed up of booting time compared to the booting time of the uncompressed method.