• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1155-1160
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• 2007

This paper presents position error for the robot localization system using the ultrasonic wave. The distance between the receiver and a beacon can be computed by using the difference between times of flight. The distance information measured by ultrasonic wave has errors. The position is calculated by distances, and this error is caused by distance errors. The position error is different from receiver¡s position. And the position is also calculated by beacon location. This paper calculates worst case position error within measuring area, and finds beacons location to reduce the position error.

• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.244-251
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• 2011

We propose a new 2-step phase-shifting digital holographic optical encryption technique and analyze tolerance error for this cipher system. 2-step phase-shifting digital holograms are acquired by moving the PZT mirror with phase step of 0 or ${\pi}$/2 in the reference beam path of the Mach-Zehnder type interferometer. Digital hologram with the encrypted information is Fourier transform hologram and is recorded on CCD camera with 256 gray-level quantized intensities. The decryption performance of binary bit data and image data is analyzed by considering error factors. One of the most important errors is quantization error in detecting the digital hologram intensity on CCD. The more the number of quantization error pixels and the variation of gray-level increase, the more the number of error bits increases for decryption. Computer experiments show the results to be carried out encryption and decryption with the proposed method and the graph to analyze the tolerance of the quantization error in the system.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.9
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• pp.947-953
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• 2011

Radome aberration error causes degradation of miss distance as well as stability of high maneuver missile system with RF seeker. A study about radome compensation method is important in this kind of missile system design. Several kinds of methods showed good compensation performance in their paper. Proposed adaptive Particle filter estimates line of sight rate excluding the radome induced error. This paper shows effectiveness of adaptive Particle filter as compensation method of radome aberration error. Robust performance of this filter depends on external aiding measurement, target acceleration. Tuning of system error covariance can make this filter unsensitive against the error of target acceleration information. This paper demonstrates practical usage of adaptive Particle filter for reducing miss distance and increasing stability against disturbance of radome aberration error through performance analysis.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.6
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• pp.922-931
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• 1995

In this paper, we propose a modified error function to improve the EBP(Error Back-Propagation) algorithm of Multi-Layer Perceptrons. Using the modified error function, the output node of MLP generates a strong error signal in the case that the output node is far from the desired value, and generates a weak error signal in the opposite case. This accelerates the learning speed of EBP algorothm in the initial stage and prevents overspecialization for training patterns in the final stage. The effectiveness of our modification is verified through the simulation of handwritten digit recognition.

• ETRI Journal
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• v.28 no.6
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• pp.793-795
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• 2006

When quadrature error exists, the shape of the M-ary phase shift keying (MPSK) signal constellation becomes skewed-elliptic. Each MPSK symbol takes on a different symbol error probability (SEP) value. The analytical results presented thus far have been derived from studies which examined the SEP problem assuming that the SEP of each MPSK symbol is equally likely; therefore, those results should not be treated as offering a complete solution. In this letter, we present a new and more complete solution to the SEP problem of MPSK by relaxing the above assumption and finding the expressions for the average as well as individual SEP in the presence of quadrature error.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.367-372
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• 2000

Accuracy of a machined component is determined by the relative motion between the cutting tool and the workpiece. One of the important factors which affects the accuracy of this relative motion is the geometric error of machine tools. In this study, geometric error is modeled using form shaping motion of machine tool, where a form shaping function is derived from the homogeneous transformation matrix. Geometric errors are measured by laser interferometer. After that, the local positioning error can be estimated from the form shaping model and geometric error data base. From this information, we can remodel the part by shifting the design surface to the amount of positional error. By generating tool path to the redesigned surface, we can reduce the machining error.

• Journal of the Semiconductor & Display Technology
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• v.19 no.3
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• pp.112-117
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• 2020

NAND flash memory is a non-volatile memory that retains stored data even without power supply. Internal memory used as a data storage device and solid-state drive (SSD) is used in portable devices such as smartphones and digital cameras. However, NAND flash memory carries the risk of electric shock, which can cause errors during read/write operations, so use error correction codes to ensure reliability. It efficiently recovers bad block information, which is a defect in NAND flash memory. BBT (Bad Block Table) is configured to manage data to increase stability, and as a result of experimenting with the error correction code algorithm, the bit error rate per page unit of 4Mbytes memory was on average 0ppm, and 100ppm without error correction code. Through the error correction code algorithm, data stability and reliability can be improved.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.2
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• pp.167-177
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• 2002

In Strapdown Inertial Navigation System(SDINS), error models based on previously proposed conversion equations between the attitude errors, are only valid in case the attitude errors are small. The SDINS error models have been independently studied according to the definition of the reference frame and of the attitude error. The conversion equations between the attitude errors applicable to SDINS with large attitude errors are newly derived. Lyapunov transformation matrices are also derived from the obtained results. Furthermore the general method, which is independent of the attitude error and the reference frame to derive SDINS error model, is proposed using the Lyapunov transformation.

• Journal of Communications and Networks
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• v.9 no.2
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• pp.167-176
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• 2007

In multimedia communication systems, efficient transmission system design should incorporate the use of matching unequal error protection (UEP), since source coders exhibit unequal bit error sensitivity. In this paper, we present UEP schemes which exploit differences in bit error protection levels in orthogonal frequency division multiplexing (OFDM) systems over frequency selective fading channels. We introduce an UEP scheme which improves the link performance with multiple transmit and receive antennas. Especially, we propose a new receiver structure based on two stage Maximum Likelihood detection (MLD) schemes which can approach the performance of a full search MLD receiver with much reduced computational complexity. In the performance analysis, we derive a generalized pairwise error probability expression for the proposed UEP schemes. Simulation results show that the proposed schemes achieve a significant performance gain over the conventional equal error protection (EEP) scheme.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.570-572
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• 2008

The modulation quality of the I/Q modulator in a wireless transmitter usually affects system performance and it mostly depends on both a nonlinearity and a distortion, from the third order intermodulation($IM_3$) signal and the error components such as an input amplitude error and a local phase error, respectively. This paper focused on how much the Single Sideband Ratio(SSR), which indicates the signal distortion, changes according to the variation of the error components. Consequently, since a desired signal, side band signal at the I/Q modulator output are also represented with those power series coefficients and the error components, the effects of the error components on SSR to meet the EVM specification of the WPAN can be clearly analyzed.