• 복합신소재구조학회 논문집
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• 제2권4호
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• pp.11-18
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• 2011

본 논문에서는 컴퓨터 시뮬레이션을 통해 강재-FRP 합성 교량용 방호울타리의 성능을 분석하였다. FRP는 Surface veil, DB 그리고 Roving 섬유로 구성하였다. FRP의 적층을 고려하기 위해 LS-DYNA에서 제공하는 재료모델 MAT58을 사용하였다. 강관과 FRP의 접촉조건을 고려하기 위해 Spot weld 옵션을 사용하였다. 실차충돌 실무 업무편람에 따라 구조적 강도성능, 탑승자 보호성능 및 충돌 후 차량의 거동에 대한 성능평가를 실시하였다. 강재-FRP 합성 방호 울타리는 성능평가를 만족하였다.

• Composites Research
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• 제29권6호
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• pp.363-368
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• 2016

본 연구에서는 복합소재를 적용한 가드레일 구조체에 대하여 비선형 유한요소 충돌해석을 수행하였다. 충돌에 대한 영향에 저항하기 위하여 [0/90/90/0]으로 적층된 Boron 계열의 보강섬유가 함침된 복합소재를 적용하였다. 또한, 지반-구조물 상호작용 모델을 적용하여 가드레일 구조체의 충돌 시 적합한 지반의 물리적 상수를 도출하였다. 특히, 가드레일의 복잡한 충돌 메커니즘을 다양한 변수 해석을 통하여 규명하였다. 변수 해석은 복합소재 지주의 두께변화와 이에 대한 충돌 성능의 영향에 초점을 두었다. 다양한 변수에 대한 해석 결과는 기존 강재를 사용한 결과와 비교하여 검증하였다.

• Advances in Automotive Engineering
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• 제1권1호
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• pp.61-77
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• 2018

In this study, the effects of sitting position of the driver on the whiplash neck injury have been analyzed experimentally by using hybrid III series 50 percentile male crash test dummy. A testing platform consisting of vehicle ground, driver foot rest, driver seat and a 3-point seatbelt has been prepared. This testing platform and the instrumented crash test dummy are prepared for tests according to the Euro NCAP whiplash testing protocol. The prepared test set-up has been exposed to 3 different acceleration-time loading curves defined in the Euro NCAP whiplash testing protocol by performing sled tests. 9 different sled tests have been performed with the combinations of 3 different seating positions of the crash test dummy and 3 different acceleration-time loading curves. The sensor data obtained from the crash test dummy and high-speed videos taken are analyzed according to the injury assessments criteria defined in the Euro NCAP whiplash testing protocol and the criticality of the whiplash injury is defined. It is seen that the backset distance of the driver head with the headrest and the height difference of the top of the head of the driver with the headrest have a great importance on whiplash injuries.

• The Journal of Asian Finance, Economics and Business
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• 제7권4호
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• pp.51-58
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• 2020

The study aims to investigate the relationship between hedging with derivatives and subsequent firm-level stock price crash risk. Our sample consists of KOSPI- and KOSDAQ-listed companies from 2004 to 2014. The total firm-year observation is 4,886. We find that hedging with derivatives is related to greater possibilities of crash risk. The results suggest that the complexity of economic and financial reporting for derivatives may aggravate the company's information opacity, ultimately increasing the crash risk. We contribute to the growing body of literature on hedging with derivatives. Academics and practitioners have debated on whether or not hedging enhances transparency or rather makes the information environment more opaque. Theoretical research on the role of corporate hedging on information environment shows that hedging enhances earnings informativeness. Meanwhile, pieces of anecdotal and empirical evidence show that the economic and financial reporting complexity of derivatives can harm information transparency. Our results shed light on the question of whether and how hedging with derivatives affects information environment by examining the relationship between hedging with derivatives and crash risk. Furthermore, our findings provide useful insights for policymakers and practitioners. Specifically, our results raise a need for a more transparent disclosure on corporate hedging activities with derivatives.

• 한국기계가공학회지
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• 제11권2호
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• pp.92-97
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• 2012

In the present the usage of bicycle has increased steeply due to well-being and convenient way of movement. In car to bicycle accident, the throw distance of bicycle is very important factor for estimating collision situation. In this study, simulations and collision tests in actual car to bicycle were executed for obtaining throw distance of bicycle. The simulations were executed by PC-CRASHTM s/w with vehicle of sedan type. Sand bags were used for the behavior of bicyclist instead of dummy and factors considered were vehicle velocity, the crashed angles and part of bicycle to vehicle, and bicycle was adult type. From the results, the throw distances of tire collision of 00 was longer than that of 450 tire crash, and the throw distances of 900 frame crash were longer than those of 450 frame crash. With based on actual crash tests and simulations, restitution coefficient of between vehicle and bicycle was estimated as 0.1. Finally the increaser vehicle velocity the longer the throw distances of bicycle and the simulation results were relatively good agreement to the results of experiment.

• 한국항공우주학회지
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• 제34권8호
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• pp.87-94
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• 2006

본 연구에서는 헬리콥터 스키드형 강착장치에 대한 비선형 충돌해석을 수행하였으며, 실제 운용중인 헬리콥터(SB427)의 강착장치 시스템이 해석에 고려되었다. 재료의 소성 거동특성과 두께변화를 고려한 3차원 유한요소 모델을 구축하였으며, LS-DYNA(Ver.970)를 활용하여 다양한 충돌 조건에 대한 전산충돌해석을 수행하여 특성을 검토하였다. 지면충돌에 기인한 강착장치의 비선형 천이응답이 설계요구조건에 대해 검토되었다. 다양한 충돌조건에 대해 비선형 충돌해석으로 예측한 최대 구조 변형량을 실험결과와 정량적으로 비교하였으며, 마찰의 영향을 고려하는 것이 해석결과의 정확성에 매우 중요함을 보였다.

• International Journal of Automotive Technology
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• 제7권6호
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• pp.715-720
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• 2006

This research investigates injury values and vehicle deformation for vehicle frontal crash compatibility. To investigate compatibility in an individual case, it is possible to impact two vehicles and evaluate the injury values and deformations in both vehicles. In this study, four tests were conducted to evaluate compatibility. A large and mini vehicle were subjected to a frontal car-to-car crash test at a speed of 48.3 km/h with an offset of 40%. An inclination car-to-car crash test using the large and small vehicle were conducted at 30 km/h at a $30^{\circ}$ angle. The results of the 48.3 km/h, car-to-car frontal crash revealed extremely high injury values on the chest and upper leg of the Hybrid III 50% driver dummy with seatbelt in the mini vehicle compared to the large vehicle. For the 30 km/h, car-to-car inclination crash, however, injury values in the small vehicle were 1.5 times higher compared to the large vehicle.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.63-71
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• 2013

The estimation of occupant injury risk at crash accident is one of the most important assessments for the vehicle crashworthiness performance. The design of safety devices such as occupant restraining system also depend on the kinematics of occupant and its injury risk. The real world in-depth accident investigation provides detailed and realistic information of vehicle damage and occupant injury as well as the accident conditions. This paper introduces a statistical analysis of NASS/CDS database and domestic accident data to correlate speed change, vehicle damage extend, and occupant injury at frontal crash. The maximum crush extend shows a linear relationship with the effective impact speed. The injury risks of the occupant with and without restraining were also respectively quantified with the crush extend. This result can be effectively used for the emergent rescue of crash victims with automatic crash notification system.

• The Journal of Asian Finance, Economics and Business
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• 제8권1호
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• pp.623-635
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• 2021

The purpose of this research is to examine the impact of information risk on the Cost of Equity (COE) and whether the risk of a stock price crash mediates the relation between information risk and COE. To test the dynamic nature of the proposed model, the two-step system GMM dynamic panel estimators are applied to all the non-financial firms listed on the Pakistan Stock Exchange (PSX) from 2007- 2018. The results of this study show that all three types of information risk, as well as the risk of the share price crash, increases the COE. The crash risk strengthens the impact of information risk on the COE. Moreover, these three information risks are correlated with each other and an increase in information quality reduces the effect of asymmetric information and improves the investor interpreting ability, while an increase in private information decreases the transparency. The finding is crucial for asset pricing, portfolio management, and information disclosure. This study contributes to the literature by providing novel findings on the impact of three different types of information risk, i.e. private information, quality of information, and transparency of information on the COE as well as whether crash risk mediates the relationship.

• 대한토목학회논문집
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• 제37권6호
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• pp.1017-1023
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• 2017

고속도로에서 발생된 교통사고 지속시간은 교통혼잡에 심각한 영향을 미친다. 일반적으로, 교통사고 지속시간은 사고의 검지시간, 대응시간, 처리시간으로 구성되며, 이 중 사고의 검지 및 대응시간은 최근 스마트폰 보급률 증가로 인해 매우 감소된 것으로 추정된다. 따라서 교통사고 처리팀에 의해 수행되는 사고 처리시간의 관리는 교통사고로 인한 교통혼잡 관리에 매우 중요한 요인이 된다. 본 연구는 고속도로 교통사고 처리에 영향을 미치는 주요 인자를 파악하는 것이 목적이다. 분석을 위해 2013년 전국 30개 주요 고속도로에서 발생한 총 6,870건의 자료를 이용하였다. 고속도로 사고 처리시간에 영향을 주는 인자 분석을 위해 Cox 모형을 활용하였다. 분석결과, 13개의 변수가 교통사고 처리시간에 영향을 미치는 것으로 나타났으며, 사고 처리시간을 증가시키는 요인은 터널에서 발생한 사고, 사망자가 발생한 사고, 사고차량수, 사고 후 상태의 상태가 전도 혹은 화재로 이어진 사고, 차량이 완파된 사고, 화물(대형) 및 트레일러 사고, 야간에 발생한 사고인 것으로 나타났다. 반면, 톨게이트에서 발생한 사고, 차-시설 사고, 승용차 사고, 종단구배가 평탄한 구간에서 발생한 사고는 다른 환경에서 발생한 사고보다 사고 처리시간을 감소시키는 것으로 나타났다. 이러한 결과는 고속도로에서 사고 발생 시 혼잡에 영향을 줄 수 있는 사고 처리시간의 감소 전략 수립을 위한 기반정보로 활용할 수 있을 것으로 기대된다.