• 한국자동차공학회논문집
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• 제16권2호
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• pp.49-57
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• 2008

The performance of crash cushion systems is certified through the full scale crash tests by the standard for installation and maintenance guidelines for roadside safety appurtenance. The impact severities of impacting vehicles in collision with crash cushion systems are rated by indices THIV and PHD. Crash test results are considered to study the performance of three crash cushion systems. In case of the frontal impact or the offset frontal impact, the results show that THIV values of three systems are very close to the threshold limit for the occupant protection. Also, the results show that PHD would be improper for the occupant protection performance index. In order to improve the occupant protection performance of crash cushions, ASI needs to be included in the impact severity index.

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

• Wind and Structures
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• 제20권5호
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• pp.643-660
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• 2015

The wind tunnel test of large-scale sectional model and computational fluid dynamics (CFD) are employed for the purpose of studying the aerodynamic appendices and mechanism on suppression for the vortex-induced vibration (VIV). This paper takes the HongKong-Zhuhai-Macao Bridge as an example to conduct the wind tunnel test of large-scale sectional model. The results of wind tunnel test show that it is the crash barrier that induces the vertical VIV. CFD numerical simulation results show that the distance between the curb and crash barrier is not long enough to accelerate the flow velocity between them, resulting in an approximate stagnation region forming behind those two, where the continuous vortex-shedding occurs, giving rise to the vertical VIV in the end. According to the above, 3 types of wind fairing (trapezoidal, airfoil and smaller airfoil) are proposed to accelerate the flow velocity between the crash barrier and curb in order to avoid the continuous vortex-shedding. Both of the CFD numerical simulation and the velocity field measurement show that the flow velocity of all the measuring points in case of the section with airfoil wind fairing, can be increased greatly compared to the results of original section, and the energy is reduced considerably at the natural frequency, indicating that the wind fairing do accelerate the flow velocity behind the crash barrier. Wind tunnel tests in case of the sections with three different countermeasures mentioned above are conducted and the results compared with the original section show that all the three different countermeasures can be used to control VIV to varying degrees.

• 한국인터넷방송통신학회논문지
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• 제18권2호
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• pp.227-235
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• 2018

최근 자동차 교통량의 증가로 인해 차량 전복사고가 급증하여 이에 따른 인명피해가 증가해왔으며, 이를 방지하기 위한 차량충돌 실험장비 및 해석프로그램 개발 등의 다양한 기술이 진보되고 있다. 본 연구에서는 적용한 차량모델은 미국 FORD사의 EXPLORER 차종이고, Rollover 해석은 차량충돌해석에 상용되고 있는 PC-Crash 프로그램을 이용하여 SUV의 전복사고 거동 및 충돌속도를 예측하였다. 그 해석결과로 FMVSS No. 208 법규를 통한 SUV차량의 실제 Rollover 거동과 비교할 때 유사한 결과를 보여주었으며, 충돌속도 및 롤각의 특성은 1000 msec 이후부터는 다소 오차율이 커지는 경향을 나타냈다. 그리고 NHTSA의 데이터베이스를 활용하여 고찰한 결과로 충돌속도 15~77 km/h, 충돌각도 $22{\sim}74^{\circ}$ 범위에서 전복사고가 가장 많이 발생함을 나타냈고, 실제 사고사례를 적용함으로써 차량 출발 위치, Roof 파손위치, 정지위치를 재현시켜 차량 Roof가 파손될 때 차량속도 및 충돌시간을 예측할 수 있었다.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.193-203
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• 2001

The Monte Carlo method was used to evaluate the reliability of crash discrimination algorithms. Through the Fast Fourier Transformation, crash pulses obtained during frontal crash tests of a mini van and a sports utility vehicle were transformed to signals in the frequency domain, and the signals were divided into basic signals and changeable signals. The changeable signals were modified through random generation, and they were combined with the basic signals. Then, the combined signals were transferred back to the time domain. In this way numerous crash pulses could be generated. For the generated pulses, crash discrimination algorithms were evaluated by examining whether they did not result in air bag deployment for the pulses requiring no air bag deployment and whether they resulted in time-to-fires faster than required time-to-fires for the pulses requiring air bag deployment. The crash discrimination algorithm in which the absolute value of the deceleration change multiplied by the velocity change or the summation of the absolute value of the deceleration change was used as a metric was Proven to be highly reliable.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.259-266
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• 2000

Crash test data from different impact modes and threshold speeds were used to assess the effects of impact conditions on air bag electronic single point sensing (ESPS) activation requirements. The requirements are expressed in terms of the desired sensor activation time based on unbelted driver dummy kinematics. A crash discriminator pre-displacement is introduced to crash recognition algorithm to the ESPS. The new crash recognition algorithm named Velocity Energy Pre-displacement(VEPD) method is developed and the ESPS algorithm based on the VEPD technique is used to assess the ESPS system performance. It is shown that VEPD method correlates very well with desired sensor activation time and meets the activation requirement.

• 소성∙가공
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• 제20권8호
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• pp.555-561
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• 2011

The energy absorbing characteristics of crash members in a car collision play an important role in controlling the amount of damage to the passenger compartment. Crash members filled with aluminum foam are expected to have reduced mass while maintaining or even improving the crashworthiness compared to the conventional hollow-beam types. Finite element simulations are carried out in the present work to assess the improvement of crashworthiness by the use of aluminum foam fillers. The numerical results agreed well with experimental measurements. Parametric studies are conducted to analyze the effect of impact velocity, weld strength, and initiator on the crash response.

• 한국자동차공학회논문집
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• 제21권5호
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• pp.97-103
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• 2013

Crash performance of the straight member was studied by FE analysis. One end of model was fixed and the other end was impacted by 1,000kg rigid mass with velocity of 16.0m/sec. The maximum and mean load were discussed to compare crash performance. The members with various section shapes were analyzed and the flange location was changed. Also, spot weld points were added in the initial buckling region to investigate its effect. Final rectangular section model which has flanges at the center and reinforcement in initial buckling region showed high enhancement in crash performance.

• 한국인터넷방송통신학회논문지
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• 제12권5호
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• pp.115-122
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• 2012

자동차 충돌해석은 다양한 형태로 구성되어 충돌중 차량에 대한 속도변화는 차량간의 충돌정도 또는 승객의 안전도를 평가하는 데 중요한 요소로 활용된다. 이로 인해 충돌해석 프로그램을 활용한 속도변화에 따른 결과치를 해석하는 방법이 필요하다. 본 연구에서는 PC-Crash 프로그램을 이용하여 노면의 마찰계수에 따라 차량속도에 따른 제동거리를 실제값과 해석값을 비교하여 마찰계수가 작을 때 오차가 큼을 알 수 있었고, 서로 다른 주 차량(MATIZ, SONATA 및 버스 적용)이 교차로에서 충돌하는 속도의 오차범위는 차량무게의 차이에 따라 최대오차는 1.2%, 1.8%, 3.1%으로 나타났다. 또한 인천대교 버스추락 사고를 재현하기 위하여 시뮬레이션을 한 결과로 다소 오차는 있었으나 사고 재구성을 검증할 수 있었다.

• 한국정밀공학회지
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• 제17권4호
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• pp.226-232
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• 2000

This paper develops a finite element model for studying the crashworthiness analysis of a mid-size truck. A simulation for a truck frontal crash to a rigid barrier using the model is performed with PAM-CRASH installed in super computer SP2. Full vehicle model is composed of 86467 shell elements, 165 beam elements and 98 bar elements, and 86769 nodes. The model uses four material model such as elastic, elastic-plastic(steel), rigid and elastic-plastic(rubber) material model which are in PAM-CRASH. Frame and suspension system are modeled with 28774 shell elements and 31412 nodes. Cab is modeled with 34680 shell elements and 57 beam elements, and 36254 nodes. Bumper is modeled with 2262 shell elements, and 2508 nodes. Axle, steering shaft, etc are modeled using beam or bar elements. Mounting parts are modeled using rigid bodies. Bodies are interconnected using nodal constrains or joint options. To verify the developed model, frontal crash test with 30mph velocity to a rigid barrier is carried out. In the crash test, vehicle pulse at lower part of b-pillar is measured, and deformed shapes of frame and driver seat area are photographed. Those measured vehicle pulse and photographed pictures are compared those from the simulation to verify the developed finite element model.