• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.4
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• pp.167-172
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• 1982

We have studied and discussed the error rate performance of Quadrature Amplitude Modulation(QAM) in an environment of cochannel QAM interference and impulsive noise. A general equation of error probability for L-level QAM signal has been derived and the error rate of the 16-QAM signal, as an example, has been calculated as functions of carrier-to-noise power ratio(CNR), carrier-to-interferer power ratio(CIR), impulsive indes, and the phase difference between signal and interferer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.775-780
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• 2004

In this paper, we propose a simple protection scheme for error prone bit positions of turbo codes using the error detection capability of the CRC, which is almost always employed in practical systems. The proposed scheme based on bit flipping with CRC offers flexibility on selecting the level of protection. Also, not having send additional parity bits or discarding useful bit positions, it offers the best error performance for a given level of protection.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.3
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• pp.66-72
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• 1984

In this paper, the error rate performance of L-level amplitude shift keying (ASK), M-ary phase shift keying (PSK) and amplitude phase keying (APK) systems have been studied in the presence of interference and noise. Using the derived error probability equations, the error rate performance of each L-level ASK and M-ary PSK system has been evaluated in terms of carrier-to-noise power ratio (CNR), carrier-to-interferer power ratio (CIR), and envelope distribution of interferer. These results are combined and then the error rate performance of APK signal has been found. Finally, the error rate performance is compared and discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.738-748
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• 2005

The ship radiated noise level fluctuates by the difference of interference and reverberation according to measurement methods and environmental conditions. These phenomena cause error of the source level estimation even in the same environment conditions. This paper describes a quantitative analysis and a reduction method for an error value to the source level estimation in spatial and temporal interference environment. The design criteria of the radiated noise measurement array composed of omni-directional hydrophones and the source level accuracy in the deep water range are given. The source level accuracy in the shallow water range is also derived based on the statistical model of the multiple reflection paths. The results are verified using the water tank experiment and the sea trial.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.3-8
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• 2016

We propose a modified form of the decision-directed least mean square (DD LMS) algorithm that is widely used in the optimization of self-adaptive equalizers, and show the modified version greatly improves the initial convergence properties of the conventional algorithm. Existing DD LMS regards the difference between a equalizer output and a quantization value for it as an error, and achieves an optimization of the equalizer based on minimizing the mean squared error cost function for the equalizer coefficients. This error generating method is useful for binary signal or a single-level signals, however, in the case of multi-level signals, it is not effective in the initialization of the equalizer. The modified DD LMS solves this problem by modifying the error generation. We verified the usefulness and performance of the modified DD LMS through experiments with multi-level signals under distortions due to intersymbol interference and additive noise.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1032-1041
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• 1999

This paper proposes on-line scheduling algorithms that reduce the largest weighted error incurred by preemptive imprecise tasks running on a single processor system. The first one is a two-level algorithm. The top-level scheduling, which is executed whenever a new task arrives, determines the processing times to be allotted to tasks in such a way to minimize maximum weighted error as well as to minimize total error. The lower-level algorithm actually allocates the processor to the tasks. The second algorithm extends the on-line algorithm studied by Shih and Liu[4] by formalizing the top-level algorithm mathematically. The numerical simulation shows that the proposed algorithm outperforms the previous works in the sense that it greatly reduces the largest weighted error.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.1
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• pp.17-30
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• 1985

The error rate performances of digital modulation systems in fluenced by impulsive noise have been investigated and discussed in the enviroment of electromagnetic interference(EMI). Using the derived equations for the probabilities of error of L-level ASK, M-ary PSK, MSK, QAM, and APK signals, the error rate performance of each system has been evaluated and compared each other. The results show that, in the case of gaussian noise enviornment, PSK system is superior to the other systems and the digital amplitude modulation systems are inferior on the contrary. In the environment of impulsive noise, the MSK at low interfere level shows the best error rate performance but in the high level interferer environment, the PSK shows the best error rate performance. Also it is known that the digital amplitude modulation systems are scarcely influenced by the variation of interfere level.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.57-62
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• 2015

The test of comparing liquid flow calibration system (approved by KOLAS) for accuracy and structure change test was performed in the test bed in order to evaluate the typical characteristics of the electromagnetic flow meters and parshall flume that are generally used in the water discharging facilities. The results of the accuracy comparing test with liquid flow calibration system showed the error of less than 2%. Pharshall plume got error up to -8.3% (low flow) from the flow rate test, but less than 4% from the accumulated flow test because of offset error at high flow rate and low flow rate. Evaluation of structual change test was tested with only parshall flume using structure and it consisted of installation angle (parshall flume and level sensor) and position change. Installation angle, water level sensor angle and position changing test for parshall flume had errors of 3.1%~-9.2%, 0.4%~-5.6% and 0.2%~1.3% respectively. Especially, the error showed the largest increase when the water level sensor measured the point of decreased flow by the structure change. Therefore, error factors (change of straight pipe length, installation of obstacle or effect of foreign substances on water level sensor) that can often occur in the field should be derived and the research for optimized installation method should be carried out continuously.

• Proceedings of the Korean Association for Survey Research Conference
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• 2002.11a
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• pp.255-274
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• 2002

We classify rotation sampling designs into two classes. The first class replaces sample units within the same rotation group while the second class replaces sample units between different rotation groups. The first class is specified by the three-way balanced design which is a multi-level version of previous balanced designs. We introduce an extended generalized composite estimator (EGCE) and derive its variance and mean squared error for each of the two classes of design, cooperating two types of correlations and three types of biases. Unbiased estimators are derived for difference between interview time biases, between recall time biases, and between rotation group biases. Using the variance and mean squared error, since any rotation design belongs to one of the two classes and the EGCE is a most general estimator for rotation design, we evaluate the efficiency of EGCE to simple weighted estimator and the effects of levels, design gaps, and rotation patterns on variance and mean squared error.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.865-869
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• 2009

An image resolution enhancement is mainly utilized as pre-processing technique for various image processing application. It requires to decrease image quality deterioration such as blurring. In this paper, we propose an image resolution enhancement algorithm using low level interpolation. In the proposed algorithm, we calculate an error using low level interpolation, estimate an error image from the calculated error. The estimated error image is added interpolated high resolution image, it become lastly reconstruction image. Our experiments obtained the average PSNR about 1dB which is improved results better than conventional method for sensitive image quality. Also, subjective image quality with edge region is more clearness. The proposed method may be helpful for applications in various multimedia systems such as image restoration.