하정석 교수

In this correspondence, we consider puncturing of low-density parity-check (LDPC) codes for additive white Gaussian noise (AWGN) channels. We show that good puncturing patterns exist and that the puncturing can be performed in a rate-compatible fashion. Furthermore, rate-compatible puncturing results in a small loss of performance with respect to threshold, namely, the punctured code is good (in terms of threshold) across a range of rates when compared with the optimal codes for each rate. This

In this paper, we consider rate compatible puncturing of low density parity check (LDPC) codes. We present a general density evolution-based procedure which finds the optimal puncturing of a based code. We show that puncturing can be performed across a range of rates and code lengths in a manner that produces punctured codes with good thresholds. This allows one to implement a single optimal LDPC code of a low rate that can be punctured across a wide range of rates without loss of threshold perf

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In this paper we study and propose an algorithm to puncture finite length low density parity check (LDPC) codes (Ha, J, et al., 2002). The introduced puncturing criterion results in good performance (for 1024 and 4096 bits) when compared with both random puncturing and dedicated LDPC codes, i.e. unpunctured codes designed for a given rate. The comparison also shows that the proposed punctured LDPC codes have better block-error rates than the dedicated codes because of longer effective block leng

Abstract In this paper, we propose a design rule of rate-compatible punctured multi-edge type low-density parity-check (MET-LDPC) code ensembles with degree-one variable nodes for the information reconciliation (IR) of continuous-variable quantum key distribution (CV-QKD) systems. In addition to the rate compatibility, the design rule effectively resolves the high error-floor issue which has been known as a technical challenge of MET-LDPC codes at low rates. Thus, the proposed design rule allows

We consider low-density parity-check code (LDPCC) design for additive white Gaussian noise (AWGN) channels with erasures. This model, for example, represents a common situation in magnetic and optical recording where defects or thermal asperities in the system are detected and presented to the decoder as erasures. We give thresholds of regular and irregular LDPCCs and discuss practical code design over the mixed Gaussian/erasures channel. The analysis is an extension of the Gaussian approximatio

Rate-compatible punctured LDPC codes have shown to perform well over a wide variety of code rates, both theoretically and practically. However it has been reported that the belief propagation (BP) decoding for these codes converges slower than for unpunctured codes. Layered BP algorithm is a modified BP algorithm that accelerates the decoding convergence by means of sequential scheduling of check node updates. In this letter, we propose an efficient scheduling of check node updates for rate-comp

In this paper, we describe fast implementations of optical flow and geometric active contours to reliably track flying vehicles. Given the position of the vehicle at time t-1, optical flow information is used to initially place an active contour in the basin of attraction of a region of interest in a given dynamical image at time t. For real-time tracking, fast convergence of the active contour as well as rapid computation of the optical flow are crucial. In this note, we describe algorithms tha

We have analytically approximated the triboelectric charge densities generated by triboelectrification reaching equilibrium over time in contact-mode TENG. It is assumed that the surface density of states (SDOS), Ns(E) is constant. The amount of electron transfer at the interface is estimated by calculating the change in vacuum energy level due to the charge density induced in the upper metal electrode and the lower metal electrode within the nanoscale separation range. Numerical results show th

A theoretical model of the transferred charges from the contact-mode triboelectric nanogenerator (TENG) was performed in this work. Based on the analytical model, a triboelectric charge density consisting of structural parameters and averaged surface DOS () was used to calculate the transferred charges, (Qsc), and the relationship between the Qsc, the dielectric constant, and the was investigated. The model presented here is the first use of the parameter-dependent triboelectric charge density t

In this thesis, we extend applications of Low-Density Parity-Check (LDPC) codes to a combination of constituent sub-channels, which is a mixture of Gaussian channels with erasures. This model, for example, represents a common channel in magnetic recordings where thermal asperities in the system are detected and represented at the decoder as erasures. Although this channel is practically useful, we cannot find any previous work that evaluates performance of LDPC codes over this channel. We are al