• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1A
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• pp.34-42
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• 2012

Low density parity check (LDPC) code is widely used, since it shows superior performance close to Shannon limit and its decoding complexity is lower than turbo code. Recently, it is used as a channel code to decode Wyner-Ziv frames in distributed video coding (DVC) system. In this paper, we propose an efficient method to design the parity check matrix H of LDPC codes. In order to apply LDPC code to DVC system, the LDPC code should have rate compatibility. Thus, we also propose a method to merge check nodes of LDPC code to attain the rate compatibility. LDPC code is designed using ACE algorithm and check nodes are merged for a given code rate to maximize the error correction capability. The performance of the designed LDPC code is analyzed extensively by computer simulations.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.179-187
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• 2004

We consider some problems of the Modified SPRT(Sequential Probability Ratio Test) method for fault detection and isolation of inertial redundant sensor systems and propose an Advanced SPRT method which solves the problems of the Modified SPRT method. The problems of the Modified SPRT method to apply to inertial sensor system come from the effect of inertial sensor errors and the correlation of parity vector components. We use a two-stage Kalman filter to remove effects of the inertial sensor errors and propose the modified parity vector and the controlled parity vector which reduces the effect of correlation of parity vector components. The Advanced SPRT method is derived form the modified parity vector and the controlled party vector. Some simulation results are presented to show the usefulness of the Advanced SPRT method to redundant inertial sensor systems.

• The KIPS Transactions:PartA
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• v.10A no.2
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• pp.83-92
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• 2003

RAID 5 is a widely-used technique used to construct disk systems of high reliability and performance. This paper proposes APGOC (Adaptive Parity Group On Cache) organization on cache to solve "small write" problem of RAID 5 especially in OLTP (On-Line Transaction Processing System) environments. In our approach, when user process makes a request for a file to kernel, the information on the read/write characteristics is added to the file data structure of the file system. With this information, data and parity cache can be managed interchangeably through parity fetching. Therefore we can enhance the cache utilization and improve the disk request response time. Our method is analyzed and evaluated with a simulation method. Comparing with previous works, we observed about 6~l3% of performance enhancement.hancement.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.10
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• pp.413-420
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• 2013

Redundant arrays of independent disks (RAID) without a power-fail-safe component in small and mid-sized business suffers from intolerably long resynchronization time after a unclean power-failure. Data blocks and a parity block in a stripe must be updated in a consistent manner, however a data block may be updated but the corresponding parity block may not be updated when a power goes off. Such a partially modified stripe must be updated with a correct parity block. However, it is difficult to find which stripe is partially updated (inconsistent). The widely-used traditional parity resynchronization manner is a intolerably long process that scans the entire volume to find and fix inconsistent stripes. This paper presents a fast resynchronization scheme with a negligible overhead for small and mid-sized RAIDs. The proposed scheme is integrated into a software RAID driver in a Linux system. According to the performance evaluation, the proposed scheme shortens the resynchronization process from 200 minutes to 5 seconds with 2% overhead for normal I/Os.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.9
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• pp.1095-1102
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• 2016

In this paper, we propose a decoding scheme that can apply to a three dimensional turbo product code(TPC) with a single parity check code(SPC). In general, SPC is used an axis with shortest code length in order to maximize a code rate of the TPC. However, SPC does not have any error correcting capability, therefore, the error correcting capability of the three-dimensional TPC results in little improvement in comparison with the two-dimensional TPC. We propose two schemes to improve performance of three dimensional TPC decoder. One is $min^*$-sum algorithm that has advantages for low complexity implementation compared to Chase-Pyndiah algorithm. The other is a modified serial iterative decoding scheme for high performance. In addition, the simulation results for the proposed scheme are shown and compared with the conventional scheme. Finally, we introduce some practical considerations for hardware implementation.

• ETRI Journal
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• v.45 no.3
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• pp.404-417
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• 2023

This paper proposed a novel method for constructing quasi-cyclic low-density parity-check (QC-LDPC) codes of medium to high code rates that can be applied in cloud data storage systems, requiring better error correction capabilities. The novelty of this method lies in the construction of sparse base matrices, using a girth greater than 4 that can then be expanded with a lift factor to produce high code rate QC-LDPC codes. Investigations revealed that the proposed large-sized QC-LDPC codes with high code rates displayed low encoding complexities and provided a low bit error rate (BER) of 10^-10 at 3.5 dB E_b/N₀ than conventional LDPC codes, which showed a BER of 10^-7 at 3 dB E_b/N₀. Subsequently, implementation of the proposed QC-LDPC code in a softwaredefined radio, using the NI USRP 2920 hardware platform, was conducted. As a result, a BER of 10^-6 at 4.2 dB E_b/N₀ was achieved. Then, the performance of the proposed codes based on their encoding-decoding speeds and storage overhead was investigated when applied to a cloud data storage (GCP). Our results revealed that the proposed codes required much less time for encoding and decoding (of data files having a 10 MB size) and produced less storage overhead than the conventional LDPC and Reed-Solomon codes.

• Journal of Animal Science and Technology
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• v.48 no.1
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• pp.9-14
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• 2006

Milk yield and its quality traits determine the dairy enterprise profitability and sustainability. Milk quality traits including somatic cell counts (SCC) is an upcoming economic challenge for dairy farming community in Korea. This study estimated the effect of parity, stage of lactation (early, mid and late lactation) on SCC, stress (blood cortisol) and immunity (blood IgG, lymphocyte and neutrophil) traits, their heritabilities and genetic correlations between them. SCS and blood neutrophil count were significantly affected by both parity and stage of lactation, however; IgG was affected by only stage of lactation, and blood cortisol and lymphocyte were not affected by both factors. The SCS has shown increasing trend with the parity, however; the difference between first and second parity, second and third parity were not significant. The SCS in early (≤90 days) and late lactation (181≤days) were higher than that of mid lactation (91～180 days). Cortisol concentration in blood was lowest in fourth parity, however; the differences among the first three parties were not significant. The IgG was higher in fourth parity compare with first parity however; all other comparisons were noted non-significant. The IgG concentration was significantly higher in early lactation than those of mid and late lactation. The blood lymphocytes were decreased with increasing parity however the differences beyond second parity were not significant. The neutrophils were increased with the increasing lactation stage however; the difference between early and mid lactation was not significant. Although heritability of SCS was still lower, but it was meaningful value (0.09) and may be considered to improve milk quality. The genetic correlations between SCS and cortisol (-0.96), and lymphocyte (-0.76) were highly negative. Heritability of cortisol was low, however genetic correlations between cortisol and lymphocyte (0.79) was highly positive. IgG with medium heritability was correlated negatively with lymphocyte (-0.88) and neutrophil (-0.98). Lymphocyte was lowly heritable and highly correlated with neutrophil concentration (0.87).This study suggested that cortisol, IgG, lymphocyte and neutrophil being positively genetically correlation with somatic cell score could be used as alternative traits to enhance milk quality in Holstein cattle. Further studies are warranted to estimate genetic relationships between immunological and production traits to increase the genetic merit of Holstein cows for milk yield, to improve animal health and economic viability under intensive management system.

• Journal of Animal Science and Technology
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• v.55 no.5
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• pp.343-349
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• 2013

Data including 1,372,050 milk records pertaining to 438,019 cows from 1983 to 2011 collected during performance tests conducted by the National Livestock Cooperative Dairy Improvement Center were used to calculate milk income and profit of individuals and investigate the effects of production levels of early lactation (parity 1 and 2, respectively). Individuals with a moderate level of early lactation stayed longer in herds. Among parity 1, the 9,000 kg or higher group had a lower mean number of lactations than the overall mean of 3.13. The 7,000 kg or lower and 10,000 kg or higher groups had lower mean life time milking days than the overall mean of 1,076.8 days. Standard deviations of lifetime traits tended to decrease as production levels increased. For parity 2, the 11,000 kg or higher group had a lower mean number of lactation than the overall mean of 3.43. The lifetime milking days was highest in the 12,000 kg group (1,212.0 days), and generally smaller in the lower groups. Profit increased as the production level of groups increased for both parity 1 and 2. In groups with low production levels, profit of parity 1 was higher than that of parity 2, while the reverse was true in groups with high production levels. These results suggest that individuals in the low production groups had a greater likelihood to be culled due to reproductive or other problems. Furthermore, the accuracy of the prediction of lifetime profit of individuals with a milk yield of 305 days seems to be higher for parity 2 than parity 1; therefore, it is desirable to predict lifetime profit using the 305d milk yield of parity 2. In conclusion, breeding goals are based on many factors in functions for the estimation of profit; however, production levels during early lactation (parity 1 and 2) can be used as indicators of profit to extend profitability.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.473-476
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• 2004

Low-Density Parity-Check (LDPC) codes are recently emerged due to its excellent performance to use. However, the parity check matrices (H) of the previous works are not adequate for hardware implementation of encoders or decoders. This paper proposes a hybrid parity check matrix for partially parallel decoder structures, which is efficient in hardware implementation of both decoders and encoders. Using proposed methods, the encoding design can become practical while keeping the hardware complexity of partially parallel decoder structures.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.11
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• pp.36-42
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• 2010

This paper presents a hybrid approach to the construction of quasi-cyclic (QC) low-density parity-check (LDPC) codes based on parallel bundles in Euclidean geometries and circulant permutation matrices. Codes constructed by this method are shown to be regular with large girth and low density. Simulation results show that these codes perform very well with iterative decoding and achieve reasonably large coding gains over uncoded system.