• Journal of the Korean Society for Precision Engineering
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• v.17 no.5
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• pp.55-62
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• 2000

In this paper, an algorithm for determining the optimal resolution has been described for measuring the actual length of circular objects. As the resolution gets higher, the measurement error in general becomes smaller because of the reduced distance per pixel. However, the higher resolution makes circular objects enlarged, which may produce an ill-conditioned system. That is, a small error in the boundary positions may result in a large error in the analysis of the circular objects. Taking this fact into account, a new measure is proposed to determine the optimal resolution. The actual errors have been calculated with various resolutions and the resolution with the minimum error has been decided as the optimal resolution. The analysis using various circles with different sizes indicates that the minimum measurement error is obtained when the whole circle appears in the screen as large as possible, regardless of the size of circle. The experimental results using real images have verified the validity of our analysis.

• Journal of the Ergonomics Society of Korea
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• v.22 no.1
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• pp.31-42
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• 2003

This study describes a modification of the technique for human error analysis in nuclear power plants (NPPs) which adopts advanced Man-Machine Interface (MMI) features based on computerized working environment, such as LCOs. Flat Panels. Large Wall Board, and computerized procedures. Firstly, the state of the art on human error analysis methods and efforts were briefly reviewed. Human error analysis method applied to NPP design has been THERP and ASEP mainly utilizing Swain's HRA handbook, which has not been facilitated enough to put the varied characteristics of MMI into HRA process. The basic concepts on human errors and the system safety approach were revisited, and adopted the process of FMEA with the new definition of Error Segment (ESJ. A modified human error analysis process was suggested. Then, the suggested method was applied to the failure of manual pump actuation through LCD touch screen in loss of feed water event in order to verify the applicability of the proposed method in practices. The example showed that the method become more facilitated to consider the concerns of the introduction of advanced MMI devices, and to integrate human error analysis process not only into HRA/PRA but also into the MMI and interface design. Finally, the possible extensions and further efforts required to obtain the applicability of the suggested method were discussed.

• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.8-22
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• 1999

This study was performed to comparatively evaluate selected Human Reliability Analysis (HRA) methods which mainly focus on cognitive error analysis, and to derive the requirement of a new human error analysis (HEA) framework for Accident Management (AM) in Nuclear Power Plants (NPPs). In order to achieve this goal, we carried out a case study of human error analysis on an AM task in NPPs. In the study we evaluated three cognitive HEA methods, HRMS, CREAM and PHECA, which were selected through the review of the currently available seven cognitive HEA methods. The task of reactor cavity flooding was chosen for the application study as one of typical tasks of AM in NPPs. From the study, we derived seven requirement items for a new HEA method of AM in NPPs. We could also evaluate the applicability of three cognitive HEA methods to AM tasks. CREAM is considered to be more appropriate than others for the analysis of AM tasks, HRMS is also applicable to the error analysis of AM tasks. But, PHECA is regarded less appropriate for the predictive HEA technique as well as for the analysis of AM tasks. In addition to these, the advantages and disadvantagesofeachmethodaredescribed.

• Journal of the Ergonomics Society of Korea
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• v.23 no.4
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• pp.9-21
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• 2004

As menu structure of household appliance is complicated, user's cognitive workload frequently occurs errors. In existing studies, errors didn't present that interpretation for cognitive factors and alternatives, but are only considered as statistical frequency. Therefore, error classification and analysis in tasks is inevitable in usability evaluation. This study classified human error throughout information process model and navigation behavior. Human error is defined as incorrect decision and behavior reducing performance. And navigation is defined as unrelated behavior with target item searching. We searched and analyzed human errors and its causes as a case study, using mobile phone which could control appliances in near future. In this study, semantic problems in menu structure were elicited by SAT. Scenarios were constructed by those. Error analysis tests were performed twice to search and analyze errors. In 1st prototype test, we searched errors occurred in process of each scenario. Menu structure was revised to be based on results of error analysis. Henceforth, 2nd Prototype test was performed to compare with 1st. Error analysis method could detect not only mistakes, problems occurred by semantic structure, but also slips by physical structure. These results can be applied to analyze cognitive causes of human errors and to solve their problems in menu structure of electronic products.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2194-2200
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• 2002

Transmission error is highly related to gear noise. In order to predict the helical gear noise, transmission error analysis is needed. Up to now, the studies for the transmission error were conducted by the modeling of helical gears only. However, since helical gears are supported by the shaft and bearing, transmission error has the effects of the elements. In this study, the procedure to consider the shaft deformation with bearing stiffness for the transmission error analysis is proposed. To do so, the relationship between gear error and shaft deformation is analytically derived. Shaft deformation with bearing stiffness is analyzed by FEM. It is measured in the experimental test rig by the non-contact displacement sensors. Using the tooth error from tooth modification and the shaft deformation, the effects of shaft on the loaded transmission error are investigated.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.168-174
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• 2001

For human error analysis, the structure and situation of a task should be analyzed in advance. The paper introduces Structured Information Analysis (SIA) as a task analysis method for error analysis, and delineates the result of application on the emergency procedure of Korean Standard Nuclear Plants (KSNPs). From the task analysis about emergency procedure of KSNP, total 72 specific task goals were identified in the level of system function, and 86 generic tasks were classified from the viewpoint of physical sameness of the task description. Human errors are dependent on task types so that the result of task analysis would be used as a basis for the error analysis on the emergency tasks in nuclear power plants.

• Journal of the Ergonomics Society of Korea
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• v.32 no.6
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• pp.535-540
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• 2013

Objective: The aim of this study is to evaluate the effectiveness and efficiency of causal links between various error causes in human error analysis. Background: As finding root causes of human error in safety-critical systems is often a cognitively demanding and time-consuming task, it is particularly necessary to develop a method for improving both the quality and efficiency of the task. Although a few methods such as CREAM have suggested causal linking between error causes as a means to enhance the quality and efficiency of human error analysis, no published research to date has evaluated the performance of the causal links. Method: The performance of the CREAM links between error causes were evaluated with 80 railway accident investigation reports from the UK. From each report, errorneous actions of operators were derived, and for each error, candidate causes were found by following the predefined links. Two measures, coverage and selectivity, were used to evaluate the effectiveness and efficiency of the links, respectively. Results: On average, 96% of error causes actually included in the accident reports were found by following the causal links, and among the total of 121 possible error causes, the number of error causes to be examined further was reduced to one-tenth on average. As an additional result of this work, frequent error causes and frequently used links are provided. Conclusion: This result implies that the predefined causal links between error causes can significantly reduce the time and effort required to find the multiple levels of error causes and their causal relations without losing the quality of the results. Application: The CREAM links can be applied to human error analysis in any industry with minor modifications.

• International Journal of Aeronautical and Space Sciences
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• v.1 no.1
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• pp.70-80
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• 2000

The attitude knowledge error model is formulated for specifically KOMPSAT attitude determination system using the Lefferts/Markley/Shuster method, and the attitude determination(AD) error analysis is performed so as to investgate the on-board attitude determination capability of KOrea Multi-Purpose SATellite(KOMPSAT) using the covariance analysis method. Analysis results show there is almost no initial value effect on Attitude Determination (AD) error and the sensor noise effects on AD error are drastically decreased as is predicted because of the inherent characteristic of Kalman filter structure. However, it shows that the earth radiance effect of IR-sensor(earth sensor) and the bias effects of both IR-sensor and fine sun sensor are the dominant factors degrading AD error and gyro rate bias estimate error in AD system. Analysis results show that the attitude determination errors of roll, pitch and yaw axes are 0.056, 0.092 and 0.093 degrees, respectively. These numbers are smaller than the required values for the normal mission of KOMPSAT. Also, the selected on-orbit data of KOMPSAT is presented to demonstrate the designed AD system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.8
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• pp.741-746
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• 2007

In this paper, we propose an accuracy analysis method for air-to-ground weapon delivery. The lethality, which is one of the most important factor to evaluate combat effectiveness of a fighter, depends on the capability to improve the accuracy of the conventional weapon delivery. We present error elements which affect the error analysis for air-to-ground weapon delivery from the initial design phase to the final validation phase. And we introduce an accuracy analysis method to reflect the error elements and to evaluate them quantitatively. We assume zero bias-error and consider random error for the weapon delivery accuracy analysis.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.13 no.1
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• pp.13-20
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• 1995

Error analysis is important in horizontal positioning. In case of error analysis, standard error ellipse is generally used to establish the precision regions, but it will be replaced by 95% confidence ellipse. It is more effective than standard error ellipse in resection for measured procedures and establishment for criterias of relative error. Therefore, In this paper deals with analysis of application to 95% confidence ellipse in horizontal positioning. This study deals with error analysis of plane trilateration network which are various types of control point. also, this paper have studied for theory of error analysis in order to using least square adjustment. Thus, This paper's conclusion are as follows; 95% confidence ellipse could be used to establish of specification in korea, also, it is possible for us to predesign for optimum surveying network by 95% confidence ellipse.