• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.157-158
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• 2008

This paper examines an adaptive coding scheme for flat fading channels to maximize the average code rate of a coded system. The proposed adaptation technique is employed by using the required free distance of a rate compatible code depending on the channel realization. First, the system will calculate the required free distance based on the instantaneous channel gain. Based on this channel gain we will select a set of convolution code to optimize the code rate with a certain performance requirement. Simulation results show that our proposal can achieve a higher code rate.

• Journal of the Semiconductor & Display Technology
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• v.19 no.3
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• pp.112-117
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• 2020

NAND flash memory is a non-volatile memory that retains stored data even without power supply. Internal memory used as a data storage device and solid-state drive (SSD) is used in portable devices such as smartphones and digital cameras. However, NAND flash memory carries the risk of electric shock, which can cause errors during read/write operations, so use error correction codes to ensure reliability. It efficiently recovers bad block information, which is a defect in NAND flash memory. BBT (Bad Block Table) is configured to manage data to increase stability, and as a result of experimenting with the error correction code algorithm, the bit error rate per page unit of 4Mbytes memory was on average 0ppm, and 100ppm without error correction code. Through the error correction code algorithm, data stability and reliability can be improved.

• Computers and Concrete
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• v.6 no.1
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• pp.59-78
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• 2009

Reliability analysis for a proposed limit state bridge design code is performed. In order to introduce reliability concept to design code, the proposed live load model is based on truck weight survey. Test data of domestic material strengths are collected to model statistical properties of member strengths. Sample RC and PSC girder sections are designed following the safety factor format of the proposed code and compared with the current design practice. Reliability indexes are calculated and examined for material and member resistance factor formats and sample calibrations of safety factors are presented. It is concluded that the proposed code provides reasonable level of reliability compared to the international design standards.

• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.223-243
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• 1995

We describe the implementation of a multi-dimensional numerical code to solve the equations for idea! magnetohydrodynamics (MHD) in cylindrical geometry. It is based on an explicit finite difference scheme on an Eulerian grid, called the Total Variation Diminishing (TVD) scheme, which is a second-order-accurate extension of the Roe-type upwind scheme. Multiple spatial dimensions are treated through a Strang-type operator splitting. Curvature and source terms are included in a way to insure the formal accuracy of the code to be second order. The constraint of a divergence-free magnetic field is enforced exactly by adding a correction, which involves solving a Poisson equation. The Fourier Analysis and Cyclic Reduction (FACR) method is employed to solve it. Results from a set of tests show that the code handles flows in cylindrical geometry successfully and resolves strong shocks within two to four computational cells. The advantages and limitations of the code are discussed.

• Journal of Communications and Networks
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• v.17 no.2
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• pp.198-202
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• 2015

This paper presents a computationally efficient implementation of a Hamming code decoder on a graphics processing unit (GPU) to support real-time software-defined radio, which is a software alternative for realizing wireless communication. The Hamming code algorithm is challenging to parallelize effectively on a GPU because it works on sparsely located data items with several conditional statements, leading to non-coalesced, long latency, global memory access, and huge thread divergence. To address these issues, we propose an optimized implementation of the Hamming code on the GPU to exploit the higher parallelism inherent in the algorithm. Experimental results using a compute unified device architecture (CUDA)-enabled NVIDIA GeForce GTX 560, including 335 cores, revealed that the proposed approach achieved a 99x speedup versus the equivalent CPU-based implementation.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.47-51
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• 2006

The variation of marine accidents and ship's insurances is to be the measurement of assessment concerned effect of importing ISM Code because each kind of ship accident's expenses and compensation for the loss have an effect on the ship's insurance and P&I insurance. Therefore in this study, we had grasped the accomplishment of importing ISM Code, using analysis of the variation of marine accidents and ship's insurances in domestic shipping companies from one year ago to 8 years after importing ISM Code. As the result of analysis, compared with the period of a year before carrying out ISM Code, marine accidents were showed a decrease of about 14.4% at 8th year of importing ISM Code. Also, the insurance had tended downward every year.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.3-7
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• 2017

Holographic data storage system (HDSS) features short access times, high storage capacities, and fast transfer rates, since the data is recorded and read not by lines but by pages within a volume of holographic material. Burst error caused by physical impact on the high density storage system becomes very longer than that of conventional storage systems. This paper proposes an LDPC product code using two LDPC code to resolve burst error. When a total code rate is similar, the performance of two LDPC code having high code rate is better than that of one LDPC code having low code rate. Also, with error factors of two-dimensional intersysbol interference and misalignment, the proposed scheme can improve the performance in holographic data storage system.

• Journal of Internet Computing and Services
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• v.19 no.3
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• pp.15-23
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• 2018

A code reuse attack is an attack technique that can execute arbitrary code without injecting code directly into the stack by combining executable code fragments existing in program memory and executing them continuously. ROP(Return-Oriented Programming) attack is typical type of code reuse attack and serveral defense techniques have been proposed to deal with this. However, since existing methods use Rule-based method to detect attacks based on specific rules, there is a limitation that ROP attacks that do not correspond to previously defined rules can not be detected. In this paper, we introduce a method to detect ROP attack by learning command pattern used in ROP attack code using RNN(Recurrent Neural Network). We also show that the proposed method effectively detects ROP attacks by measuring False Positive Ratio, False Negative Ratio, and Accuracy for normal code and ROP attack code discrimination.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.1
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• pp.65-69
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• 2010

The variations of marine accidents and ship's insurences are measures for assessing the effects of ISM Code implementation, bemuse expenses for the treatment of ship accidents and compensations for the loss have an effect on the ship's insurence. In order to understand the results and accmplishements of ISM Code implementation in Korea, the rise and the fall of marine accidents and ship's insurences were analyzed and examined in domestic shipping companies from one year before implementation to eight years after implementation of ISM Code. As the result of analysis, compared with the period of a year before implementation of ISM Code, the decrease of about 14.4% in marine accidents was shown in the 8th year after ISM Code implementation in Korea, and ship's insurance rates tended to decrease from year to year.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.117-123
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• 2013

By calculating the spectral efficiency of symmetric balance incomplete block design(BIBD) codes satisfying BER=$10^{-9}$, it can be found that ideal BIBD code design with m=2 and various q's is effective when effective power is high($P_{sr}=-10$ dBm). But BIBD code design with q > 2 and various m's can be effective when effective power is low($P_{sr}=-25$ dBm).