• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.8A
• /
• pp.1437-1440
• /
• 2001

We present a modification method for runlength limited codes based on convolutional codes. This method is based on cosets of convolutional codes and can be applied to any convolutional code without degradation of error control performance of the codes. The upper bound of maximum zero and/or one runlength are provided. Some convolutional codes which have the shortest maximum runlength for given coding parameters are tabulated.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1992.06a
• /
• pp.49-53
• /
• 1992

In many applications such as speech analysis, speech coding, speech recognition, etc., the voiced-unvoiced decision should be performed correctly for efficient processing. One of the parameters which are used for voice-unvoiced decision is zero-crossing. But the information of higher formants have not represented as the zero-crossing rate for higher formants of speech signals.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1995.06a
• /
• pp.76-80
• /
• 1995

Differential pulse code modulation 구조의 Line spectrum pairs 양자화기에 높은 차수 LSP 파라미터 값은 낮은 차수 LSP 파라미터 값보다 커야한다는 LSP 파라미터의 순서화 특징을 이용하여 양자화하는 방법을 제시한다. 31 비트/프레임에서 1 dB 이하의 스펙트럴 왜곡을 갖는 명료한 음질을 보였다. 또한 LSP 주파수의 순서화 특성은 벡터-스칼라 결합 양자화기에 적용하였다. 벡터-스칼라 결합 양자화기에서는 26비트/프레임에서 명료한 음질을 보였다. 새로운 LSP 양자화 방법들은 전송에러 발생시 성능을 시험하고, 전송 에러에 강인하도록 프레임간 예측을 위해 Moving Average 예측기를 사용한다.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.33B no.3
• /
• pp.96-108
• /
• 1996

In this paper, we propose an object-oriented coding method in low bit-rate channels using block-based motion vectors and residual image compensation. First, we use a 2-stage algorithm for estimating motion parameters. In the first stage, coarse motion parameters are estimated by fitting block-based motion vectors and in the second stage, the estimated motion parametes are refined by the gradient method using an image reconstructed by motion vectors detected in the first stage. Local error of a 6-parameter model is compensted by blockwise motion parameter correction using residual image. Finally, model failure (MF) region is reconstructed by a fractal mapping method. Computer simulation resutls show that the proposed method gives better performance than the conventional ones in terms of th epeak signal to noise ratio (PSNR) and compression ratio (CR).

• Journal of Korea Multimedia Society
• /
• v.10 no.12
• /
• pp.1551-1558
• /
• 2007

The standard of evaluating function of speech coder for mobile telecommunication can be shown in channel capacity, noise immunity, encryption, complexity and encoding delay largely. This study is an algorithm to reduce complexity applying to CDMA(Code Division Multiple Access) mobile telecommunication system, which has a benefit of keeping the existing advantage of telecommunication quality and low transmission rate. This paper has an objective to reduce the computing complexity by controlling the frequency band nonuniform during the changing process of LSP(Line Spectrum Pairs) parameters from LPC(Line Predictive Coding) coefficients used for EVRC(Enhanced Variable-Rate Coder, IS-127) speech coders. Its experimental result showed that when comparing the speech coder applied by the proposed algorithm with the existing EVRC speech coder, it's decreased by 45% at average. Also, the values of LSP parameters, Synthetic speech signal and Spectrogram test result were obtained same as the existing method.

• Proceedings of the IEEK Conference
• /
• 1999.06a
• /
• pp.679-682
• /
• 1999

This paper proposes the LSF or LSP that is the method of using to transfer the speech parameters after processed the speech to LPC, which is digital coding transferring efficiently, for the best quality and the lowest bit rate of parameters. The new revised transform algorithm between LSF and LPC coefficients is proposed. The proposed algorithm eliminates all multiplications, computes fewer operations, and reduces memory buffer sizes.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.48 no.1
• /
• pp.60-64
• /
• 2011

In this paper, we propose a new post-processing technique that removes blocking and ringing artifacts in Block discrete cosine transformation (BDCT)-coded images using bilateral filtering. The selection of filter parameters is a key issue in the application of a bilateral filter because it significantly affects the result. An efficient method of selecting the bilateral filter parameters is presented. The experimental results show that the proposed approach alleviates the artifacts efficiently in terms of PSNR, MSDS, and SSIM.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.12
• /
• pp.3003-3017
• /
• 2013

In this paper, we investigate the outage performance of a cognitive relay network. We consider mutual interference in an independent, non-identically distributed Nakagmai-m fading environment. We first derive the close-form outage probability expression, which provides an efficient means to evaluate the effects of several parameters. This allows us to study the impact of several parameters on the network's performance. We then derive the asymptotic expression and reveal that the diversity order is strictly determined by the fading severity of the cognitive system. It is not affected by the primary network. Moreover, the primary network only affects the coding gain of the cognitive system. Finally, Monte Carlo simulations are provided, which corroborate the analytical results.

• Proceedings of the IEEK Conference
• /
• 2002.06d
• /
• pp.29-32
• /
• 2002

In typical block-based video coding, the objective of RC(Rate Control) is to select the quantization parameters so that the encoder produces bits at the rate of the channel and the overall distortion is minimized. To reduce the huge amount of computations required for offline RC, there have been significant efforts to speed up the process of video encoders. Those efforts have been mainly focused on the modes for bit rate and distortion in types of coders, in terms of the quantization parameters. Because previous works related to model based online RC are based on statistics of previous frame, it occurs the problem such that allocates bits unequally without regard to current frame statistics. In this thesis, an equal bit allocation scheme using current frame statistics is proposed.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 1999.06a
• /
• pp.77-82
• /
• 1999

Information about camera operating such as zoom, focus, pan, tilt and tracking is useful not only for efficient video coding, but also for content-based video representation. A camera operating parameter measurement system designed specifically for these applications is therefore developed. This system, implemented in real time and synchronized with the video signal, measures the precise camera operating parameters. We calibrated the camera lens using a camera model that accounts for redial lens distortion. The system is then applied to infer image motion from pan and tilt operating parameters. The experimental results show that the inferred motion coincides with the actual motion very well, with an error of less than 0.5 pixel even for large motion up to 80 pixels.