• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2008년도 정기총회 및 학술발표대회
• /
• pp.513-516
• /
• 2008

The development of crash cushions is finally completed by full-scale vehicle crash tests. Since the current development of crash cushions is achieved by numerous repeated full-scale vehicle crash tests based on empirical and irrational methods, it requires a great amount of costs. In this research, the more rational procedure based on prototype design by static tests and computer simulation is suggested and it can minimize the number of full-scale vehicle crash tests.

• 한국자동차공학회논문집
• /
• 제11권1호
• /
• pp.128-136
• /
• 2003

In today's design trend of vehicle structure, crush zone is fiequently reinforced by adding a box-shaped sub-frame in order to avoid an excessive deformation against a high-speed offset barrier such as EU Directive 96/97 EC, IIHS offset test. That kind of vehicle structure design results in a relatively monotonic crash pulse for airbag ECU(Electronic Control Unit) located at non-crush zone. As for an angular crash event, the measured crash signal using a single-axis accelerometer in a longitudinal direction is usually weaker than that of frontal barrier crash. Therefore, it is not so easy task to achieve a satisfactory crash discrimination performance for offset and angular crash events. In this paper, we introduce a new crash discrimination algorithm using an electronic X-Y 2-axis accelerometer in order to improve crash discrimination performance especially for those crash events. The proposed method uses a crash signal in lateral direction(Y-axis) as well as in longitudinal direction(X-axis). A crash severity measure obtained from Y-axis acceleration is used to improve the discrimination between fire and no-fire events. The result obtained by the proposed measure is logically ORed with an existing algorithm block using X-axis crash signal. Simulation and pulse injection test have been conducted to verify the performance of proposed algorithm by using real crash data of a 2,000cc passenger vehicle.

• 한국도로학회논문집
• /
• 제9권3호
• /
• pp.91-100
• /
• 2007

도로를 이용하는 운전자들의 안전을 위해서 없어서는 안될 차량방호안전시설이 충격 흡수시설이다. 그러나 충격 흡수시설의 합리적이고 현실적인 설계방법이 미비한 상태임으로 대안없이 충돌시험에만 의존하고 있고 이것으로 인해 시간적, 물리적 손실이 큰 실정이다. 본 연구에서는 실차 충돌시험 데이터를 이용하여 삼차원의 복잡한 충돌거동에 대해 탑승자의 안전을 고려한 단자유도계 적용의 적합성을 증명하고 충격흡수시설의 거동을 분석함으로써 효과적인 단자유도계 충격흡수시설 설계법을 개발하고자 했다. 그리하여 단자유도계를 이용한 충돌해석 모델을 정립하고 충격흡수시설 설계법을 제시하였다. 충격흡수시설 설계법의 유효성을 검증하기 위해 단자유도계 설계법으로 CC2등급 충격흡수시설을 설계 제작하여 실차 충돌시험을 실시하였다. 성능시험 결과 매우 만족스러운 결과가 도출되었고 이로써 단자유도계 충격흡수시설 설계법은 충격흡수시설을 설계하는데 있어 유용한 방법중의 하나임이 증명되었다.

• 한국자동차공학회논문집
• /
• 제8권6호
• /
• pp.182-193
• /
• 2000

Several metrics have been used in crash discrimination algorithms in order to have timely air bag deployment during all frontal crash modes. However, it is still challengine to have timely air bag deployment especially during the oblique, the pole and the underride crash mode. Therefore, in this paper a new crash discrimination algorithm was proposed, using the absolute value of the deceleration change multiplied by the velocity change as a metric, and processing the metric as a function of the velocity change. The new algorithm was applied for all frontal crash modes of a minivan and a sports utility vehicle, and it resulted in timely air bag deployment for all frontal crash modes including the oblique, the pole and the underride crash mode. Moreover, it was proposed that an accelerometer be installed at each side of the rails, rockers or pillars to assess the crash severity of each side and to deploy the frontal air bags at different time especially during an asymmetric crash such as an oblique and an offset crash. As an example, the deceleration pulses measured at the left and right B-pillar·rocker locations were processed through the new algorithm, and faster time-to-fires were obtained for the air bag at the struck side for the air bag at the other side.

• 소성∙가공
• /
• 제17권3호
• /
• pp.182-188
• /
• 2008

Crash box is one of the most important automotive parts for crash energy absorption and is equipped at the front end of the front side member. The specific characteristics of aluminum alloys offer the possibility to design cost-effective lightweight structures with high stiffness and excellent crash energy absorption potential. This study deals with crashworthiness of aluminum crash box for an auto-body with the various types of cross section. For aluminum alloys, A17003-T7 and A17003-T5, the dynamic tensile test was carried out to apply for crash analysis at the range of strain from 0.003/sec to 200/sec. The crash analysis and the crash test were carried out for three cross sections of rectangle, hexagon and octagon. The analysis results show that the octagon cross section shape with A17003-T5 has higher crashworthiness than other cross section shapes. The effect of rib shapes in the cross section is important factor in crash analysis. Finally, new configuration of crash box with high crash energy absorption was suggested.

• 한국자동차공학회논문집
• /
• 제11권2호
• /
• pp.148-156
• /
• 2003

Many car manufacturers have frequently adopted an aggressive inflator and a lower threshold speed for airbag deployment in order to meet an injury requirement for unbolted occupant at high speed crash test. Consequently, today's occupant safety restraint system has a weakness due to an airbag induced injury at low speed crash event. This paper proposes a new crash algorithm to improve the weakness by suppressing airbag deployment at low speed crash event in case of belted condition. The proposed algorithm consists of two major blocks-crash severity algorithm and deployment logic block. The first block decides crash severity with two levels by means of velocity and crash energy calculation from acceleration signal. The second block implemented by simple AND/OR logic combines the crash severity level and seat belt status information to generate firing commands for airbag and belt pretensioner. Furthermore, it can be extended to adopt additional sensor information from passenger presence detection sensor and safing sensor. A simulation using real crash data for a 1,800cc passenger vehicle has been conducted to verify the performance of proposed algorithm.

• International Journal of Automotive Technology
• /
• 제7권2호
• /
• pp.179-185
• /
• 2006

Airbag deployment has been responsible for huge death, incidental injuries and broken bones due to low crash severity and wrong deployment decision. This misfortune has led the authorities and the industries to pursue uniquely designed airbags incorporating crash-sensing technologies. This paper provides a thorough discussion underlying crash sensing algorithm approaches for the subject matter. Unfortunately, most algorithms used for crash sensing still have some problems. They either deploy at low severity or fail to trigger the airbag on time. In this work, the crash-sensing algorithm is studied by analyzing the data obtained from the variables such as (i) change of velocity, (ii) speed of the vehicle and (iii) acceleration. The change of velocity is used to detect crash while speed of the vehicle provides relevant information for deployment decision. This paper also demonstrates crash severity with respect to the changing speed of the vehicle. Crash sensing simulations were carried out using Simulink, Stateflow, SimMechanics and Virtual Reality toolboxes. These toolboxes are also used to validate the results obtained from the simulated experiments of crash sensing, airbag deployment decision and its crash severity detection of the proposed system.

• Steel and Composite Structures
• /
• 제24권3호
• /
• pp.351-358
• /
• 2017

Due to the increasing competition, automotive manufacturers have to manufacture highly safe and light vehicles. The parts which make up the body of the vehicle and absorb the energy in case of a crash, are usually manufactured with sheet metal forming methods such as deep drawing, bending, trimming and spinning. The part may get thinner, thicker, folded, teared, wrinkled and spring back based on the manufacturing conditions during manufacturing and the type of application methods. Transferring these effects which originate from the forming process to the crash simulations that are performed for vehicle safety simulations, makes accurate and reliable results possible. As a part of this study, firstly, the one-step and incremental sheet metal forming analysis (deep drawing + trimming + spring back) of vehicle front bumper beam and crash boxes were conducted. Then, crash performances for cases with and without the effects of sheet metal forming were assessed in the crash analysis of vehicle front bumper beam and crash box. It was detected that the parts absorbed 12.89% more energy in total in cases where the effect of the forming process was included. It was revealed that forming history has a significant effect on the crash performance of the vehicle parts.

• 한국자동차공학회논문집
• /
• 제21권5호
• /
• pp.136-144
• /
• 2013

An extensive real world in-depth crash accident data is needed to make a precise occupant injury risk prediction at crash accidents which might be a critical information from the scene of the accident in ACNS(Automatic Crash Notification System). However it is rather unfortunate that there is no such a domestic database unlike other leading countries. Therefore we propose a numerical method, i.e., crash simulation using a sled model to make a virtual database that can substitute car crash database in real world. The proposing crash injury risk prediction is validated against a limited domestic crash accident data.

• The Journal of Asian Finance, Economics and Business
• /
• 제7권1호
• /
• pp.9-17
• /
• 2020

This study examines the effect of financial reporting opacity and audit quality on stock price crash risk using listed firms in Japan. This study is the first research to examine the effect of financial reporting opacity on crash risk using a Japanese listed company. Furthermore, the effect of audit quality on crash risk is verified. High level auditors can mitigate crash risk by playing a role as a corporate governance device mechanism to reduce agency costs. We use a logistic regression and linear regression model to test whether financial reporting opacity and audit quality affect crash risk using listed firms in the Japanese stock exchange market during the fiscal years 2015 January through 2017 February. The results of this study suggest that the financial reporting opacity variable shows a positive relationship with CRASH, which states that a firm with more opaque financial reporting increases crash risk. The results suggest also that the firms audited by Big4 auditors experience less crash risk, implying that the audit quality in Japan can be one of the factors mitigating firm's crash risk. This study provides implications for financial reporting and audit quality to external stakeholders who wants to avoid losses.