• Journal of Korean Society of Transportation
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• v.32 no.6
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• pp.589-599
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• 2014

This paper analyzes the forecasting errors of traffic volumes by comparing forecasted volumes for the opening year with the observed ones in the years after the urban railway construction in the metropolitan areas. The result shows that the average inaccuracy of traffic volumes for each station was estimated at around 7.27. Based on the confirmed factors of demand estimation errors, this study seeks for an alternative method to reduce estimation errors in feasibility studies. It is noted that there is a tendency that the inaccuracy varies by regions and the longer construction period or the shorter station spacing is, the overestimation increases. If urban railway projects are proceeded as planed, therefore, the level of the inaccuracy for traffic volume forecast will be decreased. In addition, thanks to the theoretical progress, recent estimation results show higher accuracy than before. In that sense, when we introduce the new railway line, it is necessary to make an accurate and realistic demand forecast based on actual outcomes and tendency of the previous estimation. The limitation of our study is that we only cover the errors of the initial period, the opening year and deal with the exogenous variables. Further research including other variables which might be considered to cause overestimation or errors would be needed for increasing the estimation accuracy of traffic volumes.

• Communications for Statistical Applications and Methods
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• v.3 no.1
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• pp.73-85
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• 1996

In this paper, we consider the distribution-free confidence intervals for the reliability of the stress-strength model when the stress X and strength Y depend linearly on some explanatory variables z and w, respectively. We apply these confidence intervals to the Rocket-Motor data and compare the results to those of Guttman et al. (1988). Some simulation results show that the distribution-free confidence intervals have better performance for nonnormal errors compared to those of Guttman et al. (1988), which are designed for normal random variables in respect that the former yield the coverage levels closer to the nominal coverage level than the latter.

• Bulletin of the Korean Mathematical Society
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• v.57 no.6
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• pp.1451-1473
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• 2020

Widely orthant dependence (WOD, in short) is a special dependence structure. In this paper, by using the probability inequalities and moment inequalities for WOD random variables, we study the L_p convergence and complete convergence for the partial sums respectively under the conditions of RCI(α), SRCI(α) and R-h-integrability. We also give an application to nonparametric regression models based on WOD errors by using the L_p convergence that we obtained. Finally we carry out some simulations to verify the validity of our theoretical results.

• Journal of Korean Clinical Nursing Research
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• v.24 no.2
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• pp.170-177
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• 2018

Purpose: The aim of this study was to examine effectiveness of 12-hour shifts for nurses compared to 8-hour shifts for the variables: Work-Life Balance, fatigue and work errors. Methods: In 2014, an opportunity to choose a 12-hour shift duty was given to a group of 8-hour shift nurses. In 2016, two years after this change, this study was done to compare the two groups. Data were collected using questionnaires. Data were sampled by a matching method with propensity score matching (PSM). The participants were 128 nurses: 64 nurses on 12-hour shifts and 64 nurses on 8-hour shifts. The comparison was analyzed using $x^2$ test, t-test. Results: The nurses on 12-hour shifts showed higher scores for Work-Life Balance (3.37) than the groups on 8-hour shifts (2.99)(p=.018) whereas were no statistical differences between the groups for fatigue (p=.132) or work errors (p=.703). Conclusion: The Work-Life Balance scores for nurses who chose the 12-hour shift shows an enhancement without an increase in fatigue or work errors.

• Journal of the Semiconductor & Display Technology
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• v.23 no.2
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• pp.71-75
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• 2024

This research focuses on processing unstructured data efficiently, containing various formulas in document processing and management regarding the terms and rules of domestic insurance documents using text mining techniques. Through parsing and compilation technology, document context, content, constants, and variables are automatically separated, and errors are verified in order of the document and logic to improve document accuracy accordingly. Through document debugging technology, errors in the document are identified in real time. Furthermore, it is necessary to predict the changes that intelligent document processing will bring to document management work, in particular, the impact on documents and utilization tasks that are double managed due to various formulas and prepare necessary capabilities in the future.

• The Journal of Korean Physical Therapy
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• v.26 no.6
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• pp.425-429
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• 2014

Purpose: The first purpose of this study was to evaluate whether hand muscle fatigue alters sensorimotor control of the hand in healthy subjects, using hand position sense. The second objective was to assess the repositioning variables during a 7.5-min period after the fatigue protocol. Methods: Participants performed a repeated handgrip movement to induce the fatigue condition as fast as possible, until they could no longer continue. Recordings were performed before (pre-fatigue) and after the completion of the fatigue exercises (immediately: post-fatigue, after a 2.5 min recovery, after a 5 min recovery and after a 7.5 min recovery). Results: The joint reposition test of the MP joint in the post-fatigue condition showed higher reposition errors than the prefatigue condition (p<0.05). Additionally, there was a significant difference in recovery of joint reposition errors after fatiguing exercises of the hand muscle, among groups (p<0.05). Conclusion: The fatigue of the hand muscles affected joint position sense by an alteration of somatosensory and proprioceptive information. Nonetheless, the effect of hand muscle fatigue was short-lived, since joint reposition errors decreased to post-fatigue values after 7.5 min of recovery.

• International Journal of Reliability and Applications
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• v.6 no.1
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• pp.41-51
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• 2005

The Bayes estimators of the parameters included in the complementary Weibull reliability model are obtained. In the process of deriving Bayes estimators, the scale and shape parameters of the complementary Weibull distribution are considered to be independent random variables having prior exponential distributions. The maximum likelihood estimators of the desired parameters are derived. Further, the least square estimators are obtained in closed forms. Simulation study is made using Monte Carlo method to make a comparison among the obtained estimators. The comparison is made by computing the root mean squared errors associated to each point estimation. Based on the numerical study, the Bayes procedure seems better than the maximum likelihood and least square procedures in the sense of having smaller root mean squared errors.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2473-2475
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• 2001

In trajectory tracking methods, the error values of current position and velocity are compensated to follow the given reference path and velocity. The path tracking for a wheeled mobile robot is treated in this paper. It is very difficult to implement stable trajectory tracking algorithms because mobile robots have kinematically non-holonomic constraints. For solving this problem, a velocity controller is presented in this paper. This velocity controller is designed by a PID controller which could be easily employed. In this case, velocity errors caused by system uncertainties or internal and external disturbances could exist. A neural network is used for compensating the velocity errors. Input variables of this neural network compensator are defined by differences between the velocities of the posture controller and the real velocities of the mobile robot. Simulation results show the effectiveness of the proposed controller.

• Journal of the Korea Safety Management & Science
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• v.15 no.4
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• pp.81-88
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• 2013

In Korean society, the theme of human errors in railway has been emerging as a critical issue. As far as human error studies are concerned, main trend has been inclined to be led by industrial engineering and systems science. Apart from those trends, this study empirically highlighted the relationship between depression, which has been a frequent research subject in the medical science and psychology, and accidents, with setting depression as an exogenous variable and cognitive failure and mistake as endogenous variables, respectively. Results of hypotheses test for the 204 respondents showed that driver's depression has a significant effect on accidents mediated by cognitive failure and mistake. This findings suggest the need for exploring the diverse latent factors causing human errors and for understanding the complex cognitive process as well as for establishing integrative countermeasures to mitigate human errors.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.1
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• pp.199-208
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• 2001

In this paper, an automatic route tracking algorithm using the position variables and the yaw angle of a ship is suggested, Since most autopilot systems paly only a role of course-keeping by integrating the gyrocompass output, they cannot cope with position errors between the desired route and real route of the ship resulted from a drifting and disturbances such as wave, wind and currents during navigation. In order for autopilot systems to track the desired route, a method which can reduce such position errors is required and some algorithms have been proposed[1,2]While such were turned out effective methods, they have a shortage that the rudder control actions for reducing the position errors are occurred very frequently. In order to improve this problem it is necessary to convert that error into the corresponding yaw angle and necessary to treat only yaw angle control problem. To do this a command generation algorithm which converts the rudder angle command reducing the current position error into they yaw angle command is suggested. To control the ship under disturbances and nonlinearities of the ship dynamics, the adaptive fuzzy controller is developed. Finally, through computer simulations for two ship models, the effectiveness of the suggested method and the possibility of the automatic route tracking are assured.