• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.6
• /
• pp.1259-1265
• /
• 1997

We investigate depth measurement error of a range finder based on triangulation method. Geometric analysis resulted in intuitive understanding of the error sensitivity. We show that the depth error is propostional to the distance between the object andthe camera. The measurement value has the highest accuracy when the line connecting the focal point of the camera and the object is perpendicular to the line joining the object and the light source of herange finder. Also we analyze the error using a perturbation method and verify that the results are identical through an experiment.

• Journal of information and communication convergence engineering
• /
• v.9 no.5
• /
• pp.556-561
• /
• 2011

This paper presents a new method for shift keying using the combination of scaling function and wavelet named scaling wavelet shift keying (SWSK). An algorithm for SWSK modulation is carried out where the scaling function and the wavelet are encoded to 1 and 0 in accordance with the binary input, respectively. Signal energy, correlation coefficient and error probability of SWSK are derived from error probability of frequency shift keying(FSK). The performance is analyzed in terms of error probability and it is simulated in accordance with the kind of the wavelet. Based on the results, we can conclude that the proposed scheme is superior to the performance of the conventional schemes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.5
• /
• pp.1172-1179
• /
• 1996

General adaptive noise canceller(ANC) suffers from the misadjustment of adaptive filter weights, because of the gradient-estimate noise at steady state. In this paper, an adaptive noise cancellation algorithm with speech detector which is distinguishing speech from silence and adaptation-transient region is proposed. The speech detector uses property of adaptive prediction-error filter which can filter the highly correlated speech. To detect speech region, estimation error which is the output of the adaptive filter is applied to the adaptive prediction-error filter. When speech signal apears at the input of the adaptive prediction-error filter. The ratio of input and output energy of adaptive prediction-error filter becomes relatively lower. The ratio becomes large when the white noise appears at the input. So the region of speech is detected by the ratio. Sign algorithm is applied at speech region to prevent the weights from perturbing by output speech of ANC. As results of computer simulation, the proposed algorithm improves segmental SNR and SNR up to about 4 dBand 11 dB, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.7C
• /
• pp.659-664
• /
• 2006

We propose two error correcting algorithms for high-density optical storage systems. The first algorithm reduces the false-erasure declaration by reducing the sensitivity on random errors and increases the code rate using a simple erasure indication method. The second one exploits just the known indicator flag instead of error correcting code such as Reed-Solomon(RS) code. The proposed algorithms are superior to the error correcting algorithms of conventional systems such as DVD and BD.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.1C
• /
• pp.8-13
• /
• 2011

In this paper, we show new method to find error locations of 2 eight bit symbol errors for 2 error correcting Reed-Solomon decoder. New design is much faster and has much simpler logic circuit than the former design method. This optimization was possible by partitioning the 8 bit operations into 4 bit arithgmatic and logic operations. This Reed Solomon decoder can be used for data protection of almost all digital communication and consumer electronic devices.

• Journal of Sensor Science and Technology
• /
• v.23 no.1
• /
• pp.1-6
• /
• 2014

In many medical image devices, dc noise often prevents normal diagnosis. In wireless capsule endoscopy systems, multipath fading through indoor wireless links induces inter-symbol interference (ISI) and indoor electric devices generate impulsive noise in the received signal. Moreover, dc noise, ISI, and impulsive noise are also found in optical fiber communication that can be used in remote medical diagnosis. In this paper, a blind signal processing method based on the biased probability density functions of constant modulus error that is robust to those problems that can cause error propagation in decision feedback (DF) methods is presented. Based on this property of robustness to error propagation, a DF version of the method is proposed. In the simulation for the impulse response of optical fiber channels having slowly varying dc noise and impulsive noise, the proposed DF method yields a performance enhancement of approximately 10 dB in mean squared error over its linear counterpart.

• Proceedings of the IEEK Conference
• /
• 2002.06e
• /
• pp.211-214
• /
• 2002

Under a continuous manufacturing process, two dimension inspection system causes problems as blurring effect and low resolution and requires position calibration between frames. One dimension inspection system is, therefore, being researched as a substitution. In this paper, we implement mechanism of switching memory and processing data for reasonable one dimension inspection system. Redundant weft image and noise was suggested to be reduced by new method using modified morphological process and masked erosion process. From resulting image, line data and possible error information were obtained and constructed as a structure. Finally, error detecting algorithm was performed with this data structure. Processing time of error detecting was 0.625ms per line in applied system and experiment showed 94.7% of error detecting ability. This method is 20% faster in speed and 2.7% higher in error detecting ability comparing with the present method.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.12A
• /
• pp.1948-1959
• /
• 1999

The error rate performance of the proposed $\pi$/4-differential quadructure phase shift keying( $\pi$/4-DQPSK) with nonredundant multiple error correction is analyzed for Nakagami fading channel. The scheme for differential detection of $\pi$/4-QPSK with nonredundant multiple error correction utilizes the output that employ the received signal delayed by more than two time slots. It was observed that the performance increased as the error correction capability increased.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37C no.11
• /
• pp.1054-1063
• /
• 2012

In this paper, we introduce basic theories, effects and applications of the unequal error protection (UEP) system that is expected to play a major role in the future multi-layered broadcast system. Also we show results of surveys on the various previous studies and standards about the UEP systems, and we give prospects of standardizations and future applications of UEP based on the surveys.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.2 no.2
• /
• pp.82-102
• /
• 2008

Packet losses tend to occur during short error bursts separated by long periods of relatively error-free transmission. There is also a significant spatial correlation in loss among the receiver nodes in a multicast session. To recover packet transmission errors at the transport layer, tree-based protocols construct a logical tree for error recovery before data transmission is started. The current tree construction scheme does not scale well because it overloads the sender node. We propose a scalable recovery tree construction scheme considering these properties. Unlike the existing tree construction schemes, our scheme distributes some tasks normally handled by the sender node to specific nodes acting as repair node distributors. It also allows receiver nodes to adaptively re-select their repair node when they experience unacceptable error recovery delay. Simulation results show that our scheme constructs the logical tree with reduced message and time overhead. Our analysis also indicates that it provides fast error recovery, since it can reduce the number of additional retransmissions from its upstream repair nodes or sender node.