• Journal of Communications and Networks
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• v.5 no.4
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• pp.354-364
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• 2003

A general method for the evaluation of the symbol error probability (SER) of ultra wideband (UWB) systems with various kind of modulation schemes (N-PAM, M-PPM, Bi-Orthogonal), in presence of multipath channel, multiuser and strong narrowband interference, is presented. This method is shown to be able to include all the principal multiaccess techniques proposed so far for UWB, time hopping (TH), direct sequence (DS) and optical orthogonal codes (OOC). A comparison between the performance of these multiple access and modulation techniques is given, for both ideal Rake receiver and minimum mean square error (MMSE) equalizer. It is shown that for all the analyzed multiple access schemes, a Rake receiver exhibits a high error floor in presence of narrowband interference (NBI) and that the value of the error floor is in-fluenced by the spectral characteristics of the spreading code. As expected, an MMSE receiver offers better performance, representing a promising candidate for UWB systems. When the multiuser interference is dominant, all multiple access techniques exhibit similar performance under high-load conditions. If the number of users is significantly lower than the spreading factor, then DS outperforms both TH and OOC. Finally 2PPM is shown to offer better performance than the other modulation schemes in presence of multiuser interference; increasing the spreading factor is proposed as a more effective strategy for SER reduction than the use of time diversity.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.1
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• pp.1205-1210
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• 2001

This paper describes a methodology using neural network to compensate the nonlinear error of deriving speed for electric differential system included in electric vehicle. An electric differential system which drives each of the left and right wheels of the electric vehicle independently. The electric vehicle driven by induction motor has the nonlinear speed error which depends on a steering angle and speed command. When a vehicle drives along a curved road lane, the speed unblance of inner and outer wheels makes vehicles vibration and speed reduction. To compensate for the speed error, we collected the speed data of the inner wheel and outer wheel in various speed and the steering angle data by using an manufactured electric vehicle and the real system. According to the analysis of the acquisited data, we designed the differential speed control system based on a speed error compensator using neural network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8C
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• pp.832-837
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• 2005

This paper presents a design method for fixed-width squarer that receives a W-bit input and produces a W-bit squared product. To efficiently compensate for the quantization error, modified Booth encoder signals (not multiplier coefficients) are used for the generation of error compensation bias. The truncated bits are divided into two groups (major/minor group) depending upon their effects on the quantization error. Then, different error compensation methods are applied to each group. By simulations, it is shown that the performance of the proposed method is close to that of the rounding method and much better than that of the truncation method and conventional method. It is also shown that the proposed method leads to up to $28\%\;and\;27\%$ reduction in area and power consumption compared with the ideal squarers, respectively.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.168-176
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• 2015

Due to the reduction in device feature size, transient faults (soft errors) in logic circuits induced by radiations increase dramatically. Many researches have been done in modeling and analyzing the susceptibility of sequential circuit elements caused by soft errors. However, to the best knowledge of the authors, there is no work which has well considerated the feedback characteristics and the multiple clock cycles of sequential circuits. In this paper, we present a new method for evaluating the susceptibility of sequential circuit elements to soft errors. The proposed method uses four Error Propagation Probability Matrixs (EPPMs) to represent the error propagation probability of logic gates and flip-flops in current clock cycle. Based on the predefined matrix union operations, the susceptibility of circuit elements in multiple clock cycles can be evaluated. Experimental results on ISCAS'89 benchmark circuits show that our method is more accurate and efficient than previous methods.

• Journal of the Korean Society of Safety
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• v.29 no.3
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• pp.91-97
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• 2014

This study aims to suggest a measure to reduce industrial accident and secure adaptation to the industrial safety regulation policies by empirically establishing the effects of stress from adaptation to the industrial safety regulation on the human error, one of direct causes of industrial accident to the target groups of the industrial safety regulation policies. This study as for content range examines the stress from adaptation to the industrial safety regulation, job satisfaction, human error, and as for spatial range, this study performed an empirical research on the workers of 24 companies located within Chungcheong region centers district among 153 companies nationwide that uses 7 chemicals by introducing PSM (process safety management) system of the Ministry of Employment & Labor as of January 2012. Based on these results and suggestions there are five(5) necessities to reduce industrial safety regulations adaptation stress and human error generation, first(1st) is the necessity of understanding influential factors to stress, second(2nd) is the necessity to customized vocational training, third(3rd) is improving enhance system of job satisfaction, forth(4th) is preparing stress-reduction program, and fifth(5th) is introducing on-site restrictive action of advanced country as politics items.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.2
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• pp.151-156
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• 2017

Communication performance requirements are described as QoS parameters in multimedia communication Protocols including SCTP. One of the important QoS parameters is the reliability of the transfer. As a QoS parameter, the reliability defines error detection, report and correction mechanisms. Including SCTP, conventional error control mechanisms, however, do not consider the integrated viewpoint of multimedia data. In this paper, I have designed and proposed the multimedia oriented error control method based on multimedia characteristics. The proposed scheme should have the reduction effect of the communication resources such as frame buffer, procesing power and bandwidth as well as satisfy the requirements of users.

• The Transactions of the Korea Information Processing Society
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• v.4 no.8
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• pp.1995-2006
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• 1997

Because of formlessness and sightlessness of software, sytematic quality management is hard to implement. But we attemped collective quality management as hardware production by configuration management and settled on software quality management standard outlines. We are implementing efficient quality management by software quality management according as these standard guidelines. In this study, we study error management supporting functions as an attempt of development of software quality management supporting system which can support quality management activity by reduction and early finding of error input, and represent various visual output elements which can help error management supporting functions. And we represent the background of construction of this software quality management system and searched effects which we can get when we use the error management supporting function.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.29 no.2
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• pp.14-24
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• 2021

This study aims to examine probable human errors when landing an airplane by the use of SHERPA(systematic human error reduction and prediction approach) and propose methods for preventing the predictive human errors. It has been reported that human errors are concerned with a lot of accidents or incidents of an airplane. It is significant to predict presumable human errors, particularly in the operation mode of human-automation interaction, and attempt to reduce the likelihood of predicted human error. By referring to task procedures and interviewing domain experts, we analyzed airplane landing task by using HTA(hierarchical task analysis) method. In total, 6 sub-tasks and 19 operations were identified from the task analysis. SHERPA method was used for predicting probable human error types for each task. As a result, we identified 31 human errors and predicted their occurrence probability and criticality. Based on them, we suggested a set of methods for minimizing the probability of the predicted human errors. From this study, it can be said that SHERPA can be effectively used for predicting probable human error types in the context of human-automation interaction needed for navigating an airplane.

• Journal of the Korea Safety Management & Science
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• v.15 no.4
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• pp.73-80
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• 2013

Because the damages of corrosion resulting from the chloride ion are very serious, many research studies have been performed to measure the penetration depth of the chloride ion. However, there is a problem with data selection obtained from collection during experiments. In this study, it appears that the collected data are not conformed to a normal distribution. The result of this study will play a very important role, as a first step for the development and construction of a forecasting system to help determine a reliable service lifetime of marine structures.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.4
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• pp.188-193
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• 2005

The purpose of this paper is to develop a more precise damper model of the joint for the quantification of the joint mechanical properties. We modified the linear damper model of a knee joint model to nonlinear one. The normalized RMS errors between the simulated and measured joint angle trajectories during passive pendulum test became smaller with the nonlinear damper model than those of the linear one which indicates the nonlinear damper model is better in precision and accuracy. The error between the experimental and simulated knee joint moment also reduced with the nonlinear damper model. The reduction in both the trajectory error and the moment error was significant at the latter part of the pendulum test where the joint angular velocity was small. The nonlinearity of the damper was significantly greater at thin subject group and this indicates the nonlinearity is a useful index of joint mechanical properties.