• International Journal of Highway Engineering
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• v.14 no.1
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• pp.85-94
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• 2012

The term "incident duration time" is defined as the time from the occurrence of incident to the completion of the handling process. Reductions in incident durations minimize damages by traffic accidents. This study aims to develop models to identify factors that influence incident duration by investigating traffic accidents on highways. For this purpose, four models were established including an integrated model (Model 1) incorporating all accident data and detailed models (Model 2, 3 and 4) analyzing accidents by location such as basic section, bridges and tunnels. The result suggested that the location of incident influences incident duration and the time of arrival of accident treatment vehicles is the most sensitive factor. Also, significant implications were identified with regard to vehicle to vehicle accidents and accidents by trucks, in night or in weekends. It is expected that the result of this study can be used as important information to develop future policies to manage traffic accidents.

• Journal of Korean Society of Transportation
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• v.25 no.5
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• pp.135-148
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• 2007

Understanding the relation between characteristics of an accident and its duration is crucial for the efficient response of accidents and the reduction of total delay caused by accidents. Thus the objective of this study is to model accident duration using an AFT metric model. Although the log-logistic and log-normal AFT models were selected based on the previous studies and statistical theory, the log-logistic model was better fitted. Since the AFT model is commonly used for the purpose of prediction, the estimated model can be also used for the prediction of duration on freeways as soon as the base accident information is reported. Therefore, the predicted information will be directly useful to make some decisions regarding the resources needed to clear accident and dispatch crews as well as will lead to less traffic congestion and much saving the injured.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.6
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• pp.1017-1023
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• 2017

Duration induced by freeway crashes has a critical influence on traffic congestion. In general, crash duration composes detection and verification, response, and clearance time. Of these, the crash clearance time determined by a crash clearance team has attracted considerable attention in the freeway congestion management since the interest of the first two time stages faded away with increasing ubiquitous mobile phone users. The objective of this study is to identify the critical factors that affect freeway crash clearance time using a Cox's proportional hazard model. In total, 6,870 crash duration data collected from 30 major Korean freeways in 2013 were used. As a result, it was found that crashes during the night, with trailer or larger size truck, and in tunnel section contribute to increasing clearance time. Crashes associated with fatality, completed damage of crashed vehicle (s), and vehicles' fire or rollover after crash also lead to increasing clearance time. Additionally, an increase in the number of vehicles involved resulted in longer clearance time. On the other hand, crashes in the vicinity of tollgate, by passenger car, during spring, on flat section, and of car-facility type had longer clearance time. On the basis of the results, this paper suggested some strategic plans and mitigation measures to reduce crash clearance time on Korean freeway systems.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.197-205
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• 2015

Offshore structures for the gas production are exposed to the risk of gas leaks, and gas explosions can result in fatal damages to the primary structures as well as secondary structures. To minimize the damage from the critical accidents, the study of the dynamic response of structural members subjected to blast loads must be conducted. Furthermore, structural dynamic analysis has to be performed considering relationships between the natural frequency of structural members and time duration of the explosion loading because the explosion pressure tends to increase and dissipate within an extremely short time. In this paper, the numerical model based on time history data were proposed considering the negative phase pressure in which considerable negative phase pressures were observed in CFD analyses of gas explosions. The undamped single degree of freedom(SDOF) model was used to characterize the dynamic response under the blast loading. A blast wall of FPSO topside was considered as an essential structure in which the wall prevents explosion pressures from the process area to utility and working areas. From linear/nonlinear transient analyses using LS-DYNA, it was observed that dynamic responses of structures were influenced by significantly the negative time duration.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1074-1075
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• 2015

본 구명조끼는 해양 사고시 구조되기까지의 시간을 단축시키며 구조되기까지의 생존율을 높여 주기 위해 연구 하였다. 본 구명조끼는 구명조끼와 LED를 결합하여 야간 사고 시 지속적인 구조요청을 가능하게 한다. 또한 구명조끼 내부에 발열체를 내장 시킴 으로서 해양사고 시 사망원인의 1순위인 저체온증이 오기까지의 시간을 연장시켜 구조되기까지의 생존율을 높여 준다.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.215-217
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• 2012

인터넷 사용이 보편화 되면서, 이를 악용하는 공격도 지속되고 있다. 이와 같이 네트워크를 통해 전파되는 다양한 공격으로부터 시스템을 보호하기위하여 DDoS 공격 대응 시스템과 스캐닝 공격 탐지 시스템, 스팸형 악성코드 탐지 시스템 등 다양한 보안 시스템들이 사용되고 있다. 본 논문에서는 다양한 인터넷 침해사고에 대응하기 위한 이기종 보안 시스템에서 탐지한 공격 로그를 분석하여 각 시스템별 공격 IP의 공격 지속시간을 확인하고, 서로 다른 침해사고 모니터링 시스템에서 탐지된 공격 IP의 연관 관계를 분석한다.

• 전기의세계
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• v.22 no.6
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• pp.19-23
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• 1973

본고에서는 우리나라 전력공급설비의 정지율 및 신뢰도수준에 대해서 알아보았으며 내용은 다음과 같다. 1. 아직 충분한 자료분석이 되어있지 않으며, 금후의 보다 충실한 자료정비가 기대된다. 2. 발전설비는 화력단위기당의 3-6% 사고정지율을 예상하고 있으며, 수력의 경우에는 무시할 수 있을 정도이다. 3. 154kV 송전설비에 대해서는 변압기가 3대에 1대, 차단기는 14대에 1대, 단로기는 36대에 1대, 그리고 모선은 약 30회선에 1회선이 매년 사고에 의한 정지를 경험하고 있다. 5. 배전설비는 100kM에 대해서 년 17건의 사고정지와 사고지속시간 3시간이며, 수용가 평균신뢰도는 대략 99.6%(30시간 공급지장)으로 추측된다. 6. 공급신뢰도는 스스로 적정한 수준이 존재하는것이며, 무조건 높은것이 타당한 것은 아니다. 7. 공급지장비용의 평가가 금후에 해결되어야 한다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.344-344
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• 2011

진공인터럽터는 진공차단기에서 실제 사고전류차단시 발생하는 아크소호 및 차단을 담당하는 매우 중요한 부분이다. 일반적으로 교류차단기는 일시적으로 에너지가 공급되지 않는 전류 영점에서 아크소호 및 전류차단이 이루어진다. 일반적으로 아크가 발생하는 전극분리시점에서 아크가 소호되는 전류영점까지의 시간을 아크지속시간(arcing time)이라고 한다. 일단 진공 인터럽터 내부의 접점이 분리됨과 동시에 아크가 발생하게되면 이때 진공인터럽터는 아크지속시간동안 고온의 아크에 의한 접점손상을 최소화하기 위해 아크의 거동을 적절히 제어하여 아크에너지를 접점표면상에 골고루 분산시켜야 한다. 현재 진공인터럽터에 사용되는 아크제어 방식에는 크게 횡자계 방식과 축자계 방식이 있다. 본 논문에서는 횡자계 방식 중 spiral type 접점을 사용하여 25 kA의 전류차단시험을 진행하면서 아크전압을 취득하는 동시에 아크이미지를 촬영하여 아크지속시간동안의 아크의 거동을 분석하였는데 특히 본 실험에서는 전체 아크지속시간동안의 아크상태천이과정이 가장 잘 관찰되는 비교적 긴 아크지속시간을 설정하여 실험을 진행하였으며 이때 접점손상이 아크거동 및 차단성능에 미치는 영향을 중점적으로 다루었다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.5
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• pp.1-14
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• 2020

The aim of this study is to analyze effects of factors on the number of vehicles involved in traffic accidents on freeway sections. In previous studies about traffic accident severity, the analysis of accidents involving multiple vehicles was insufficient. However, multiple-vehicle accidents are likely to cause casualties and are the main reasons increasing accident duration and social costs. In this study, the number of vehicles involved in an accident was interpreted as the result of the accident, not as the cause of the accident, and the impacts of each accident factor were analyzed using a multinomial logit model. The results indicate that multiple-vehicle accidents are mainly related to following factors: nighttime, driver's faults, obstacles on the road, a downhill slope, heavy vehicles, and freeway mainline sections including tunnels and bridges.

• Explosives and Blasting
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• v.37 no.4
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• pp.10-16
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• 2019

Information on overpressure, positive phase duration, and impulse are required to assess the effects of shock waves or pressure waves on the structure. In this study, the overpressure and positive phase duration were determined by applying the Multi-Energy Method, which is found to be effective in analyzing the explosion of vapor clouds. Based on the total heat of combustion estimated in the cyclohexane vapor cloud explosion in the Nypro Ltd(UK), overpressure and positive phase duration at the distance of 40, 80, 120, 160, 200, 240, 280, 320, 360(m) from the source of explosion were evaluated. Overpressure was shown to decrease exponentially and positive phase duration increased almost linearly with distance. A probit function was used to assess the probability of damages for the structures at each distance using the overpressure and impact obtained at the above mentioned distances. The Analyses of probability of damages have shown that there is a high probability of collapse at distances within 120m, major damage to structures within 240m, and minor damage and breakage of window panes of structures occur over the entire distances.