• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.61-71
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• 2014

As the occupancy rate of the flash memory increases in the storage media market for the embedded system and the semi-conductor industry grows, the demand and supply of flash memory is increasing by a big margin. They are especially used in large quantity in the smart phones, tablets, PC, SSD and Soc(System on Chip) etc. The flash memory is divided into the NOR type and NAND type according to the cell arrangement structure and the NAND type is divided into the SLC(Single Level Cell) and MLC(Multi Level Cell) according to the number of bits that can be stored in each cell. Many tests have been performed on NOR type such as BIST(Bulit-In Self Test) and BIRA(Bulit-In Redundancy Analysis) etc, but there is little study on the NAND type. For the case of the existing BIST, the test can be proceeded using external equipments like ATE of high price. However, this paper is an attempt for the improvement of credibility and harvest rate of the system by proposing the BIST for the MLC NAND type flash memory of Finite State Machine structure on which the pattern test can be performed without external equipment since the necessary patterns are embedded in the interior and which uses the MLC NAND March(x) algorithm and pattern which had been proposed for the MLC NAND type flash memory.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.321-340
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• 2016

The Compressive Video Sensing (CVS) is a useful technology for wireless systems requiring simple encoders but handling more complex decoders, and its rate-distortion performance is highly affected by the quantization of measurements and reconstruction of video frame, which motivates us to presents the Space-Time Quantization (ST-Q) and Motion-Aligned Reconstruction (MA-R) in this paper to both improve the performance of CVS system. The ST-Q removes the space-time redundancy in the measurement vector to reduce the amount of bits required to encode the video frame, and it also guarantees a low quantization error due to the fact that the high frequency of small values close to zero in the predictive residuals limits the intensity of quantizing noise. The MA-R constructs the Multi-Hypothesis (MH) matrix by selecting the temporal neighbors along the motion trajectory of current to-be-reconstructed block to improve the accuracy of prediction, and besides it reduces the computational complexity of motion estimation by the extraction of static area and 3-D Recursive Search (3DRS). Extensive experiments validate that the significant improvements is achieved by ST-Q in the rate-distortion as compared with the existing quantization methods, and the MA-R improves both the objective and the subjective quality of the reconstructed video frame. Combined with ST-Q and MA-R, the CVS system obtains a significant rate-distortion performance gain when compared with the existing CS-based video codecs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.8
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• pp.2013-2022
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• 1996

Cyclic Codes can be used for burs(or time slot) synchronization as well as error detection as that the overhead bits of the burst, which would be nessary to seperate burst synchronization and error detection systems, may be eliminated. In this paper a new method for combined burst synchronization and error detection is proposed which requires CRC decoding once only, while the previous method which inspects channel error after searching for burst synchronization requeires CRC decoding twice. The proposed method has the advantage of simple implementation and reducing processing time over the previous one, still showing the same detection perfdormance. It may occur that a burst different from the actually transmitted one is falsely accepted in the presence of channel errors. The exact expression for the false acceptance probability is newly presented through a simple derivation basied on the fact that it is determined by channel errors but not by detection methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3A
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• pp.213-220
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• 2009

Cooperative diversity is a promising technique for range extension and diversity increase without the use of multiple transmit antennas at the user equipment. In this paper, we propose a cooperative hybrid automatic repeat request relay method with adaptive retransmission to increase the throughput when the SNR of a source user is low. In the proposed method, the source user transmits the first segment of a codeword to relay users and a base station. If the base station fails to recover the information from the received packet, it requests the source or some relay users to retransmit the packet previously sent. In addition, the retransmission type of a selected user is chosen from repetition or incremental redundancy according to the quality of systematic bits in a turbo codeword. Simulation results show that the proposed method improves the throughput compared to conventional methods, and the improvement is significant when the source user has a low SNR.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.3
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• pp.44-53
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• 2010

The H.264/AVC has been designed to use 9 directional intra prediction modes for removing spatial redundancy. It also employs high correlation between neighbouring block modes in sending mode information. For indication of the mode, smaller bits are assigned for higher probable modes and are compressed by predicting the mode with minimum value between two prediction modes of neighboring two blocks. In this paper, we calculated the statistical probability of prediction modes of the current block to exploit the correlation among the modes of neighboring two blocks with several test video sequences. Then, we made the probable prediction table that lists 5 most probable candidate modes for all possible combinatorial modes of upper and left blocks. By using this probability table, one of 5 higher probable candidate modes is selected based on RD-optimization to reduce computational complexity and determines the most probable mode for each cases for improving compression performance. The compression performance of the proposed algorithm is around 1.1%~1.50%, compared with JM14.2 and we achieved 18.46%~36.03% improvement in decoding speed.