• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.2
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• pp.41-53
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• 2010

Traffic safety assessment is often accomplished by analyzing the number of crashes occurring in some geographic space over certain specific time duration. In this paper, we introduce a procedure that can efficiently analyze spatial and temporal changes in traffic crashes before-and-after implementation of a certain traffic controlling measure. For the analysis, crash frequency data before-and-after closing a major highway around St. Louis in Missouri was collected through Transportation Management System(TMS) database that is maintained by Missouri Department of Transportation (MoDOT). In order to identify any spatial and temporal pattern in crashes, each crash is pinpointed on a map using the dynamic segmentation in GIS. Then, the identified pattern is statistically confirmed using an analysis of variance table. The advantage of this approach is to easily assess spatial and temporal trend of crashes that are not readily attainable otherwise. The results from this study can possibly be applied in enhancing the highway safety assessment procedure. This paper also makes several suggestions for future development of a comprehensive transportation data system in Korea which is similar to MoDOT's TMS database.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.5
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• pp.9-15
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• 1996

A silicon microaccelerometer is designed and fabricated using silicon epitaxial layers for automotive electronic airbag applications. A cantilever structure is chosen for high sensitivity and piezoresistive detection method is adopted for circuit simplicity and low cost. An optimum design is used to find optimum microstructure sizes for maximum sensitivity subject to performance requirements and design constraints on natural frequency, damping ratio, maximum allowable stress and microfabrication limitations. The microaccelerometer is fabricated by micromachining processing steps, composed of material-selective and orientation-dependent chemical etching techniques. Fabricated prototype shows a sensitivity of 88.6$\mu\textrm{V}$/g within a resonant frequency of 1.75KHz. Estimated performance of the microaccelerometer is compared with measured one. Discrepancy between the theoretical values and the experimental values is discussed together with possible sources of the errors.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.820-825
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• 2008

In the article 16 of the domestic rolling stock crashworthiness regulations, the collision acceleration level during collision accidents should remain under the maximum 7.5g and the average 5g. By the way, the accelerations obtained in crash simulations and tests contain many kinds of high frequency components due to numerical oscillations or noisy signals. So, this paper aims to develop reliable post-processing methods to filter high frequency oscillations and extract the rigid body motions of passenger rail cars. For this study we used the 1-dimensional dynamic model of KHST (Korean high-speed train), and evaluated acceleration data at the driver's area in the first power car and the passenger area in the following trailer.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.28-33
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• 2014

Vibro ripper worked by high frequency vibration is developed to do rock fragmentation and work of ripper is the different concept with other existing breakers. The gear box-shank welded joint of vibro ripper is very important part to deliver vibromotive force to tooth, so this part should endure high frequency vibration environments. The purposes of this study are to choose the optimal welding conditions for fatigue strength. The conditions were made using three kind of shank materials and two kind of filler metals. Shank materials are Hadox-hituf, Posten80 and AR400, and filler metals are CSF-71T and CSF-81T. The fatigue test was conducted each condition. Fracture surface was observed to estimate fracture characteristics of welded joint using SEM.

• Journal of Korean Society of Transportation
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• v.31 no.4
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• pp.85-94
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• 2013

The Continuous Risk Profile (CRP) has been well known to be the most accurate and efficient among existing network screening methods. However, the classical CRP uses safety performance functions (SPFs) which require a huge investment to construct a database system. This study aims to suggest a new CRP method using average crash frequencies of homogeneous groups, instead of SPFs, as rescaling factors. Hierarchical clustering analysis is performed to classify freeway segments into homogeneous groups based on the data of AADT and number of lanes. Using the data from I-880 in California, the proposed method is compared to other several network screening methods. The results show that the proposed method decrease false positive rates while it does not produce any false negatives. The method developed in this study can be easily applied to screen freeway networks without any additional complex database systems, and contribute to the improvement of freeway safety management systems.

• Journal of the Korean Society for Railway
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• v.10 no.1 s.38
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• pp.57-66
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• 2007

1974. 8. 15 SeoulMetro, beginning with the first electric railway established at six cities, so it is managing mass transportation of traffic. Especially, in case of seoul, It is managing that from one to eight lines, 286.9km, 265 stations have installed and now it is carrying about 5.5million of passengers everyday, and 2,000million passengers a year. So accident is increasing from the station every year. For this measure, SeoulMetro prepares safety fence for passengers crash but, as suicides or people who watch the accident took place, for at the bottom of passengers crash protection, PSD installing is needed. Even though, PSD is managing ATO section but, in controlling SeoulMetro, one to four lines sections are (ATS, ATC)section. Between as ATS, ATC section, ATO section, subway gate and PSD must have opened and crossed always at the time. And the interlock control corrosion protection gate, managing skills with installation, method, using in history, apply to 10rail cars one train sets, and maximum applying 2224% sections of passengers congested that consideration is to be needed. So 2004, SeoulMetro improved technology and basie design of PSD at ATS section. Based on this, from 2005.4 to 2006.6, using subway 2lines per 12stations set the model installation(full type 11stations, half type 1station) After installing in case of success, it is going about to suggest that effective analysis and hereafter subject.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.2
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• pp.33-43
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• 2022

The number of car crashes increases along with the increasing number of vehicles. Hence, diverse initiatives on traffic accidents have been implemented, targeting zero crash fatalities. According to the 3rd Traffic Safety Master Plan of 2016, the current standard selecting road accident black spots prioritizes locations with the high cumulative death toll. While this standard is suitable for roads that a city government manages to some extent, it is not suitable for roads less than 20 meters that a borough (Gu) handles. The roads under the supervision of a borough do not have enough death toll, and thus improvements on its road accident black spots are highly limited. In addition, discovering the causes of traffic accidents is not easy when the number of car accidents is obtained by considering only fatal accidents, which are relatively low in number. Therefore, including all traffic accidents might identify causes of accidents and result in better advancements. Therefore, this research follows rational decision-making and suggests new National Traffic Safety Master Plan standards. These new standards are obtained by comparing accident costs between the location of fatal crashes and road accident black spots. The analysis result shows that considering all types of accidents yields better results. For example, a Three-way Intersection in front of Zion Day Care Center, one of the selected spots under the current standard, has lower road crash costs than Sinchon Intersection, a selected spot under a new standard. Therefore, the study concludes that the standards to select road accident black spots need to include traffic accident severity and road crash costs.

• Journal of Power System Engineering
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• v.6 no.3
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• pp.24-30
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• 2002

The deformation and fracture behaviors of both Al2O3 and Ni 4.5wt.%Al plasma thermal spray coating were investigated by an acoustic emission method. Plasma thermal spray coating is formed by a process in which melted particles flying with high speed towards substrate, then crash and spread on the substrate surface cooled and solidified in a very short time, stacking of the particles makes coating. A tensile test is conducted on notch specimens in a stress range below the elastic limit of substrate. A bendind test is done on smooth specimens. The waveforms of AE generated from the both test coating specimens can be classified by FFT analysis into two types which low frequency(type I) and high frequency(type II). The type I waveform is considered to corresponds exfoliation of coating layers and type II waveform corresponds the plastic deformation of notch tip. The fracture of the coating layers can estimate by AE event and amplitude, because AE features increase when the deformation generates.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.3
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• pp.319-324
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• 2018

The collision problem is one of the design factors that must be carefully considered for the risk of collision occurring during the operation of ships and offshore structures. This paper presents the main results of the ship collision study, and its main goal is to analyze potential crash scenarios that may occur in the FLNG (Floating Liquefied Natural Gas) considering the likelihood and outcome. Consideration being given to vessels visiting the FLNG and surrounding vessels navigating around, such as functionally supported vessels and offloading carriers. The scope includes vessels visiting the FLNG facility such as in-field support vessels and off-loading carriers, as well as third party passing vessels. In this study, based on QRA (quantitative risk assessment), basic research methods and information on collision are provided. Based on the assumptions and methodologies documented in this study, it has been possible to clarify the frequency of collision and the damage category according to the type of visiting ship. Based on these results, the risk assessment results related to the collision have been derived.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.903-912
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• 2007

One of the crucial factors which determine the quality and the accuracy of SEA model is how subsystems are defined. Experimental SEA technique had been a unique way to divide entire systems accurately for mid-frequency range, until FEA based virtual FRF response technique, virtual SEA method presented. Virtaul SEA has been developed for predictive SEA tool in early design process. In this study, Modal analysis results from modified crash FE model is used for Statistical transfer matrix. Observation nodes on the cockpit are grouped by attractive substructuring method based on point to point transfer and correlation matrix. Complex cockpit structure is divided into subsystems by automatic substructuring. Comparison with experimental SEA results validates the application of Virtual SEA to cockpit.