• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.2 no.2
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• pp.31-40
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• 1998

Spectral analysis by energy method is given for a fully discrete methods for hyperbolic integro-differential equations with a weakly singular kernel. Stability and error estimates in $H^1$-norm are derived.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.1
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• pp.78-84
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• 2014

The rotation of a spindle unit must be accurate for high-quality machining and to improve the quality of the machine tools.Therefore, the proper measurement of the rotation accuracy and ensuring a proper analysis are very important. Separate processes are necessary because spindle errors and roundness errors associated with the test balls can both factor into the measured rotation error values. We used three methods to discern test ball errors and analyzed which could be deemed as the most proper technique in a test of the rotation accuracy of the main spindle of a machine tool.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.19-24
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• 2004

A number of creep data were collected and filed for type 316LN stainless steels through literature survey and experimental data produced in KAERI. Using these data, polynomial equations for predicting creep life were obtained for Larson Miller (L-M), Qrr-Sherby-Dorn (O-S-D) and Manson-Haferd (M-H) parametric methods. In order to find out the suitability for them, the relative standard error (RSE) and standard error of estimate (SEE) values were obtained by statistical process of creep data. The O-S-D parameter showed better fitting to creep-rupture data than the L-M or the M-H parameters, and the three parametric methods did not generate the large difference in the SEE and the RSE values.

• Journal of Korean Port Research
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• v.10 no.2
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• pp.61-68
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• 1996

The main problems in structural analysis by Finite Eelement Method are difficulty in making data file and error estimation. For decreasing these problems' pays. have been suggesting the adaptive mesh refinement and error estimation method. Posteriory error estimation methods suggested by Jang[1], Babuska[2,3], Ohtsubo[8,9], and this paper. Comparing these methods and examine their properties. According this paper, In the problem supposed having singularity, the method suggested by this paper is good, But the problem supposed having no singularity, the method suggested by Jang[1] is good. For decreasing the effect of initial mesh in p-refinement, make application h-refinement at first and apply p-refinement, and confine polynomial's degree to two, for making program simply by plural mesh models are not needed.

• Journal of the Korean Society of Safety
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• v.31 no.1
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• pp.132-138
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• 2016

The purpose of this study was to develop safety competences, a set of behavioral indicators of each competence and measuring methods of behavioral indicators for preventing human error of nuclear power plants(NPPs). The safety competences and behavioral indicators were derived from the five steps consisted of derivation of preliminary competence items through literature review, content analysis, interview(FGI, BEI), examination of content validity and decision making of final indicators. The results showed that 13 core safety competences and 35 behavior indicators were derived finally. In addition, the methods of measuring safety competences or behavioral indicators such as Behaviorally Anchored Rating Scale (BARS), Behavior Observation Scale (BOS) were developed and suggested.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.2
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• pp.37-43
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• 2007

ANOVA is widely used for measurement system analysis. It assumes that the measurement error is normally distributed, which may not be seen in certain industrial cases. In this study, the exact and bootstrap confidence intervals for precision-to-tolerance ratio (PTR) are obtained for the cases where the measurement errors are normally and non-normally distributed and the reproducibility variation can be ignored. Lognormal and gamma distributions are considered for non-normal measurement errors. It is assumed that the quality characteristics have the same distributions of the measurement errors. Three different bootstrap methods of SB (Standard Bootstrap), PB (Percentile Bootstrap), and BCPB (Biased-Corrected Percentile Bootstrap) are used to obtain bootstrap confidence intervals for PTR. Based on a coverage proportion of PTR, a comparative study of exact and bootstrap methods is performed. Simulation results show that, for non-normal measurement error cases, the bootstrap methods of SB and BCPB are superior to the exact one.

• Communications for Statistical Applications and Methods
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• v.9 no.3
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• pp.853-864
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• 2002

In the analysis of categorical data subject to misclassification errors, the observed cell proportions are adjusted by a misclassification probabilities and estimates of variances are adjusted accordingly. In this case, it is important to determine the extent to which misclassification probabilities are homogeneous within a population. This paper considers methods to evaluate the power of chi-squared tests for homogeneity with complex survey data subject to misclassification errors. Two cases are considered: adjustment with homogeneous misclassification probabilities; adjustment with heterogeneous misclassification probabilities. To estimate misclassification probabilities, logistic regression method is considered.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.2
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• pp.121-130
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• 2023

Finite element analysis is widely used to predict the structural stability and tooth contact performance of gears. This study focused on the effect of finite element modeling conditions of a spur gear on the simulation result and the model simplification. The gear body and teeth, teeth width, configuration of mesh, frictional coefficient, and simulation time interval (gear mesh cycle division) were selected for model simplification for gear analysis. The static transmission error during a single-gear mesh cycle was calculated to represent the performance of the gear, and the elapsed time was measured as a simplification factor. Contact stress distribution was also checked. The differences in maximum transmission error and elapsed time depending on the model simplification methods were analyzed. After all simplification methods were estimated, an optimal combination of the methods was defined, and the result was compared with that of the most detailed modeling methods.

• Journal of the Korean School Mathematics Society
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• v.5 no.1
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• pp.69-86
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• 2002

This study accordingly brought the analysis of the error into focus to instruct the liner inequality efficiently. Students, in result, committed errors: misused data(14.6%), misinterpreted problem(15.0%), logically invalid inference(2.7%), misunderstood theorem or definition(22.1%), unmatched solution(22.4%), technical error(17.5%), omission of solving process(5.7%). Through the analysis of preceding errors, I try to emphasize the following in instructing students: First, you must emphasize studying of concept of the liner inequality and instruct students in the use of that Second, you must minimize the error by searching for the error that students are apt to commit and showing the anti-example when you instruct them in the liner inequality. Third, after evaluation, you must tell the result to students, and show many forms of the liner inequality with various means lest they should commit the same error. Therefore, if an instructor gives lessons to the students studying the instructive methods in order not to make errors about the contents mentioned above, it will help students understand much faster and arouse their curiosities and interests in lessons, and so they will take lessons willingly.

• Journal of Wellbeing Management and Applied Psychology
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• v.7 no.1
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• pp.27-33
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• 2024

Purpose: This study investigates human error accidents in the Korean railway sector, emphasizing the need for systematic management to prevent such incidents, which can have fatal consequences, especially in driving-related jobs. Research design, data and methodology: This paper analyzed data from the Aviation and Railway Accident Investigation Board and the Korea Transportation Safety Authority, examining 240 human error accidents that occurred over the last five years (2018-2022). The analysis focused on accidents in the driving, facility, electric, and control fields. Results: The findings indicate that the majority of human error accidents stem from negligence in confirmation checks, issues with work methods, and oversight in facility maintenance. In the driving field, errors such as signal check neglect and braking failures are prevalent, while in the facility and electric fields, the main issues are maintenance delays and neglect of safety measures. Conclusions: The paper concludes that human error accidents are complex and multifaceted, often resulting from a high workload on engineers and systemic issues within the railway system. Future research should delve into the causal relationships of these accidents and develop targeted prevention strategies through improved work processes, education, and training.