• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.53-60
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• 2020

The bogies of railway vehicles are one of the most critical components for service. Fatigue defects in the bogie can be initiated for various reasons, such as material imperfection, welding defects, and unpredictable and excessive overloads during operation. To prevent the derailment of a railway vehicle, it is necessary to evaluate and detect the defect of a connection weldment between the car body and bogie accurately. The safety of the bogie weldment was checked using an ultrasonic test, and it is necessary to determine the occurrence of defects using a learning method. Recently, studies on deep learning have been performed to identify defects with a high recognition rate with respect to a fine and similar defect. In this paper, the databases of weldment specimens with artificial defects were constructed to detect the defect of a bogie weldment. The ultrasonic inspection using the wedge angle was performed to understand the detection ability of fatigue cracks. In addition, the convolutional neural network was applied to minimize human error during the inspection. The results showed that the defects of connection weldment between the car body and bogie could be classified with more than 99.98% accuracy using CNN, and the effectiveness can be verified in the case of an inspection.

• Journal of Korean Society of Transportation
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• v.35 no.1
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• pp.25-36
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• 2017

The purpose of this study is to analyze traffic accident reduction effect of the introduction of motorcycle safety inspection. To analyze the effect of motorcycle inspection, we first estimate the number of defective motorcycles, and calculate the probability of accident occurrences caused by the defect using four year traffic accident data. Finally, we estimate the number of reduced accidents due to the introduction of the inspection and the total reduced accident cost. In this study, we analyzed three scenarios. It is analyzed that when the safety inspection system is applied to all motorcycles, 642 cases of traffic accidents and 325 million won per year of traffic accident costs are reduced. It is approximately 0.1% of 2014 total traffic accident cost of 26.5725 trillion won per year. It suggests that the cost of traffic accidents and traffic accidents due to vehicle factors are reduced when the safety inspection system is introduced.

• Fire Science and Engineering
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• v.19 no.1 s.57
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• pp.59-69
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• 2005

There were little available data of vehicular incendiary fires. We investigated fires by inflammable gasoline and papers. cloths in the interior and exterior of vehicles. Fires in the interior and exterior of vehicles were carried out under the several conditions by incendiary methods and vehicle's windows. We knew that dominant factor of combustion is direction of wind at that time in vehicle's fire. And we knew that the other mark of combustion pattern in vehicle's fire could be a clue for solving the problem in discerning the place to which we sotted fire between the general fire and arson.

• Journal of Korean Society of Transportation
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• v.25 no.3
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• pp.65-74
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• 2007

Vehicle inspection is a system to help all vehicles function safely through periodic maintenance. Vehicle inspections have been performed since 1962 in Korea by the government in order to reduce traffic accidents due to vehicle defects. Also, vehicle inspections may help protect citizens against uninsured vehicles and illegal vehicle remodeling by discovering and disclosing those vehicles. The prime objective of vehicle inspection is to guarantee all vehicles drive safely on the road by inspecting and fixing items which can affect traffic accidents. In addition, vehicle inspections may help to improve the public order related to vehicle operations and prevent crime through the confirmation of vehicle identity and authentication of ownership. Although there are many benefits of vehicle inspection. there are some negative opinions of the system. In this study, a methodology to analyze the effectiveness of the vehicle inspection system quantitatively in terms of traffic safety was developed. According to the developed methodology. accidents were reduced by 23.735, which is 11% of the total number of accidents in 2005.

• Journal of Korean Society of Transportation
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• v.27 no.2
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• pp.47-56
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• 2009

Effective detection and correction of outliers of raw traffic data collected from the field is of keen interest because reliable traffic information is highly dependent on the quality of raw data. Global positioning system (GPS) based traffic surveillance systems are capable of producing individual vehicle speeds that are invaluable for various traffic management and information strategies. This study proposed a locally weighted regression (LWR) based filtering method for individual vehicle speed data. An important feature of this study was to propose a technique to generate synthetic outliers for more systematic evaluation of the proposed method. It was identified by performance evaluations that the proposed LWR-based method outperformed an exponential smoothing. The proposed method is expected to be effectively utilized for filtering out raw individual vehicle speed data.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.58-64
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• 2010

As a modem urban train is getting complex in terms of high-technology in its systems and components, the failure management should be performed with scientific and systematic technique. FMEA is a technique to analyze the failure trends of component parts and influences to the higher level system in order to discover the design incompleteness and potential defects, which is for improving reliability. Especially, FMECA (Failure Mode Effects, and Criticality Analysis) is used in case that the criticality that has an immense influence to the system is important. In case of urban train, in its design and manufacturing steps, FMEA is frequently used as an analysis technique to meet the safety objectives and eliminate potential hazards/failures since the concepts of reliability of train is introduced these days. Though, FMEA technique in the maintenances steps lacks in its investigation and applications yet. FMEA is also not applied to the trains operated by Seoul metro in the design and manufacture steps excepts the newest trains. In this paper, through analyzing the failures/maintenance data of the belt-type door systems used in trains operated in Seoul metro Line 1, which is accumulated in RIMS (Rolling-stock Information Maintenance System), FMEA procedures to the belt-type door engines are proposed. Especially, an effort is made, to approach the detailed FMECA procedures to the door magnet valve and switch and door engine devices which vastly influences the customer safety and satisfaction.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.436-446
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• 2023

In the field of safety-critical systems, analyzing the effects of various failure factors (failure modes) is essential through Failure Mode and Effects Analysis (FMEA). However, with the increasing importance of software in systems, applying FMEA analysis to the design phase has become challenging. This paper proposes the use of Automatic FMEA, which can automatically perform FMEA using model-based design techniques, and presents a case study of FMEA for automotive engines. A comparison is made between the model-based Automatic FMEA analysis tool and existing FMEA tools. The study aims to demonstrate the performance of the Automatic FMEA analysis tool and propose future research plans.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.167-173
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• 2009

It is important to study on the traffic accident severity reduction because traffic accident is an issue that is directly related to human life. Therefore, this research developed countermeasure to reduce traffic accident severity considering various factors that affect the accident severity. This research developed the Accident Severity Prediction Model using the collected accident data from Seohaean Expressway in 2004~2006. Through this model, we can find the influence factors and methodology to reduce accident severity. The results show that speed limit violation, vehicle defects, vehicle to vehicle accident, vehicle to person accident, traffic volume, curve radius CV(Coefficient of variation) and vertical slope CV were selected to compose the accident severity model. These are certain causes of the severe accident. The accidents by these certain causes present specific sections of Seohaean Expressway. The results indicate that we can prevent severe accidents by providing selected traffic information and facilities to drivers at specific sections of the Expressway.