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Cheong H.-Y.,Namseoul University
Journal of Convergence Information Technology | Year: 2012

It is known that Luby Transform codes provide an efficient scheme to transmit information over the binary erasure channels without fixing the rate. Belief propagation algorithm is a fast decoding algorithm for LT codes but for small code block it requires a large overhead. In this paper an efficient decoding scheme, called on-the-fly belief propagation (OFB), is proposed for short block length LT codes. The proposed algorithm has the desirable performance in terms of both overhead and complexity. Simulation results show that the proposed algorithm allows for a 41.2% reduction with c=0.1 and a 18.3% reduction with c=0.01 in the overhead with respect to the conventional belief propagation algorithm. And the complexity of the proposed algorithm is largely reduced to that of belief propagation algorithm which has the minimum computational complexity. Source

Lee H.-W.,Namseoul University
Journal of Convergence Information Technology | Year: 2012

This paper describes an acoustic echo canceller with BSS(blind signal separation) for doubletalking. Acoustic echo canceller may be deteriorated or diverged during double-talk period. So we use BSS technology to estimate the near-end signal and to get the error signal which is eliminated the near-end signal from the residual signal. We assume that the near-end path is single channel and the acoustic echo path is multi-channel. And we use a copy of coefficients of the echo canceller for the mixing coefficients of the multi-channel. The blind signal separation method extracts the near-end signal from dual microphones by iterative computations with 2nd-order statistical character in the closed reverberation environment. The acoustic echo canceller using this method operates irrespective of double-talking. We verified performances of the proposed acoustic echo canceller by simulations. The results show that the acoustic echo canceller with this method improves ERLE(echo return loss enhancement) of more about 20dB than the normal echo canceller, and operates stably without a divergence of coefficients even double-talk period. Source

Choi S.,Namseoul University
Journal of Computer Virology and Hacking Techniques | Year: 2015

The growing company that provides high quality service to every customer by introducing a cloud system organization. However, the information needs diverse and different cloud systems, so every cloud system can act as a security system that provide appropriate cloud systems. Cloud services are becoming complicated and diversified depending on concerns about cloud security continues, the growing need of professionalism held by the cloud service (CSB : cloud service brokerage) companies. Thus, to analyze the various services, find my support legislation to solve, security and delete compatibility issues, the services of the best new business through service offerings tailored to the environment, and will implement the necessary management services which which is brokerage (CSB). This study presents a brokerage (CSB) development model, and suggests policy measures that apply to the co-operation that I am having difficulties in cloud service business models. © 2015, Springer-Verlag France. Source

Lee S.,Inha Technical College | Lee B.-J.,Namseoul University
Surface and Coatings Technology | Year: 2012

In the present work, we report the formation of residual oxide layer during chemical-mechanical-planarization (CMP) process in the carbon nanotube (CNT) via interconnects and some feasible solutions for its removal. Residual oxide layer makes electrically poor contact between CNTs and metal resulting in high contact resistance in CNT via interconnects. We adopt post-CMP processes such as hydrofluoric acid (HF) or Ar plasma treatment to remove the residual oxide layer. X-ray photoelectron spectroscopy (XPS) was used to confirm the chemical state of samples before and after the post-CMP process. Silicon and oxygen peaks from silicon-based oxide layer observed after the CMP process were disappeared and reduced in its intensity by the post-CMP process, respectively. Furthermore, via resistance decreased more than 1 order of magnitude after the post-CMP process. It is found that the post-CMP process provides good electrical contact between CNTs and metal by removing the residual oxide layer. © 2011 Elsevier B.V. Source

This paper proposes an inference methodology that can minimize the spreading effect caused by the occurrence of a feeder fault, a feeder overload, a main transformer fault, or a main transformer overload problem in a distribution system under a heavy load condition. First, the load transfer procedure is decomposed into multisteps and multistages. Then, a new inference methodology for searching the goal nodes as well as the fail nodes based on the local minimum tree search is developed. © 2012 IEEE. Source

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