• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.96-101
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• 2009

In this study, a risk-appearance frequency evaluation model for railway level-crossing accidents is developed with the frequency estimation based on the accident history. It follows the worldwide common safety management approach and reflects the operation conditions and accident properties of the domestic railway system. The risk appearance frequency evaluation process contains a development of accident scenarios by defining the system configurations and functions, and a frequency estimation of hazardous events based on the accident history. The developed model is verified with the accident history during 5 years('03-'07) for 3 hazardous events: 'Being trapped in level crossing(Hl)', 'Crossing during warning signal(H2)' and 'Breaking through/detouring the barrier(H3)'. This risk appearance frequency evaluation model will be combined with a consequence evaluation model so as to offer full risk assessment for the railway accident. The accident risk assessment will contribute to improving the safety management of the railway system.

• Earthquakes and Structures
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• v.18 no.1
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• pp.1-14
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• 2020

The vehicle-bridge interaction (VBI) analysis might be cumbersome and computationally expensive in bridge engineering due to the necessity of solving large number of coupled system of equations. However, VBI analysis can provide valuable insights into the dynamic behavior of highway bridges under specific loading conditions. Hence, this paper presents a numerical study on the dynamic behavior of a conventional highway bridge under strong near-field and far-field earthquake motions considering the VBI effects. A recursive substructuring method, which enables solving bridge and vehicle equations of motion separately and suitable to be adapted to general purpose finite element softwares, was used. A thorough analysis that provides valuable information about the effect of various traffic conditions, vehicle velocity, road roughness and effect of soil conditions under far-field and near-field strong earthquake motions has been presented. A real-life concrete highway bridge was chosen for numerical demonstrations. In addition, sprung mass models of vehicles consist of conventional truck and car models were created using physical and dynamic properties adopted from literature. Various scenarios, of which the results may help to highlight the different aspects of the dynamic response of concrete highway bridges under strong earthquakes, have been considered.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.934-942
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• 2005

MANET(Mobile Ad hoc NETwork) routing protocols have merits and demerits under the specific situations. Because it is not clear which protocol is the best under all situations, a suitable routing protocol should be selected depending on the traffic and moving characteristics of nodes. The aim of this paper is to select an appropriate routing protocol to be used by the Korea Coal Corporation. So we designed working scenarios such as coal mining and tunnel supporting that reflected mobile characteristics of nodes. We constructed coal mining and tunnel supporting topology, and analyzed the performance of MANET routing protocols. This result can be used as a basis to select a MANET routing protocol in underground tunnel environment and other mine of the Korea Coal Corporation.

• Journal of Environmental Impact Assessment
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• v.14 no.3
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• pp.117-126
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• 2005

This study was executed to know the best matrix of photochemical ozone reduction in the metropolitan area. For this object, we used the OZIPR(Ozone Isopleth Plotting Package for Research) model for comparing the effectiveness of VOCs and NOx amount variation about the ozone creation. Among the various ozone reduction scenarios, 50% reduction of VOCs from organic solvent and road traffic respectively was the best matrix for ozone reduction. Although it needs more accurate assessment and confirmation of VOCs and NOx emission amount data, according to existing data, the control of VOCs is the best way for photochemical ozone reduction in Seoul.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.10
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• pp.4176-4197
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• 2020

Botnet is a type of dangerous malware. Botnet attack with a collection of bots attacking a similar target and activity pattern is called bot group activities. The detection of bot group activities using intrusion detection models can only detect single bot activities but cannot detect bots' behavioral relation on bot group attack. Detection of bot group activities could help network administrators isolate an activity or access a bot group attacks and determine the relations between bots that can measure the correlation. This paper proposed a new model to measure the similarity between bot activities using the intersections-probability concept to define bot group activities called as B-Corr Model. The B-Corr model consisted of several stages, such as extraction feature from bot activity flows, measurement of intersections between bots, and similarity value production. B-Corr model categorizes similar bots with a similar target to specify bot group activities. To achieve a more comprehensive view, the B-Corr model visualizes the similarity values between bots in the form of a similar bot graph. Furthermore, extensive experiments have been conducted using real botnet datasets with high detection accuracy in various scenarios.

• Journal of Communications and Networks
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• v.13 no.4
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• pp.319-326
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• 2011

Beamforming techniques have been successfully utilized for traffic channels in order to solve the interference problem. However, their use for control channels has not been sufficiently investigated. In this paper, a (semi-) centralized beamforming strategy that adaptively changes beam patterns and controls the total transmit power of cells is proposed for the performance enhancement of the common channel in hierarchical cell structure (HCS) networks. In addition, some examples of its practical implementation with low complexity are presented for two-tier HCS networks consisting of macro and pico cells. The performance of the proposed scheme has been evaluated through multi-cell system-level simulations under optimistic and pessimistic interference scenarios. The cumulative distribution function of user geometry or channel quality has been used as a performance metric since in the case of common control channel the number of outage users is more important than the sum rate. Simulation results confirm that the proposed scheme provides a significant gain compared to the random beamforming scheme as well as conventional systems that do not use the proposed algorithm. Finally, the proposed scheme can be applied simultaneously to several adjacent macro and pico cells even if it is designed primarily for the pico cell within macro cells.

• Journal of Trauma and Injury
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• v.34 no.3
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• pp.212-217
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• 2021

Various medical scenarios have arisen with the prolonged coronavirus disease 2019 (COVID-19) pandemic. In particular, the increasing number of asymptomatic COVID-19 patients has prompted reports of emergency surgical experiences with these patients at regional trauma centers. In this report, we describe an example. A 25-year-old male was admitted to the emergency room after a traffic accident. The patient presented with stuporous mentality, and his vital signs were in the normal range. Lacerations were observed in the left eyebrow area and preauricular area, with hemotympanum in the right ear. Brain computed tomography showed a contusional hemorrhage in the right frontal area and an epidural hematoma in the right temporal area with a compound, comminuted fracture and depressed skull bone. Surgical treatment was planned, and the patient was intubated to prepare for surgery. A blood transfusion was prepared, and a central venous catheter was secured. The initial COVID-19 test administered upon presentation to the emergency room had a positive result, and a confirmatory polymerase chain reaction (PCR) test was administered. The PCR test confirmed a positive result. Emergency surgical treatment was performed because the patient's consciousness gradually deteriorated. The risk of infection was high due to the open and unclean wounds in the skull and brain. We prepared and divided the COVID-19 surgical team, including the patient's transportation team, anesthesia team, and surgical preparation team, for successful surgery without any transmission or morbidity. The patient recovered consciousness after the operation, received close monitoring, and did not show any deterioration due to COVID-19.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.1
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• pp.165-174
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• 2019

They are frequently used today in public places such as street, subway, school or library. Since users can sometimes print documents that contain confidential data using Printer Kiosks, the devices should store and manage the documents securely. In this paper, we identify potential security threats in Printer Kiosks and suggest practical attack scenarios that can take place. To show the feasibility of suggested attack, we analyzed network traffic that were generated by the real Printer Kiosk device. As a result of our analysis, we have found that attackers can access other users' scanned files and access other users' documents from Printer Kiosk's home page. We confirmed that using our attack, we could retrieve other users' personal data.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.6
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• pp.2838-2858
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• 2019

Traditional channel models for vehicle-to-vehicle (V2V) communication usually assume fixed velocity in static scattering environment. In the realistic scenarios, however, time-variant velocity for V2V results in non-stationary statistical properties of wireless channels. Dynamic scatterers with random velocities and directions have been always utilized to depict the non-stationary statistical properties of the channel. In this paper, a non-stationary geometry-based cooperative scattering channel model is proposed for multiple-input multiple-output (MIMO) V2V communication systems, where a birth-death process is used to capture the appearance and disappearance dynamic properties of moving scatterers that reflect the time-variant time correlation and Doppler spectrum characteristics. Moreover, our model has more straight and concise to study the impact of the vehicular traffic density on channel characteristics and thus avoid complicated procedure in deriving the analytical expressions of the channel parameters and functions. The numerical results validate our analysis and demonstrate that setting important parameters of our model can appropriately build up more purposeful measurement campaigns in the future.

• Journal of Broadcast Engineering
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• v.24 no.2
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• pp.243-250
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• 2019

In this paper, we propose a system for processing and analyzing drone image information which can be applied variously in disasters-security situation. The proposed system stores the images acquired from the drones in the server, and performs image processing and analysis according to various scenarios. According to each mission, deep-learning method is used to construct an image analysis system in the images acquired by the drone. Experiments confirm that it can be applied to traffic volume measurement, suspect and vehicle tracking, survivor identification and maritime missions.