• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.407-408
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• 2006

Passenger safety is one of the most important considerations in the purchase of an automobile. A curtain-type air bag is increasingly adapted in deluxe cars for protecting passengers from the danger of side clash. Inflator housing is a main part of the curtain-type air bag system for supplying high-pressure gases to pump up the air bag-curtain. Although the inflator housing is fundamental in designing a curtain-type air bag system, flow information on the inflator housing is very limited. In this study, we measured instantaneous velocity fields of a high-speed flow ejecting from the inflator housing using a dynamic PIV system. From the velocity field data measured at a high frame-rate, we evaluated the variation of the mass flow rate with time. From the instantaneous velocity fields of flow ejecting from the airbag inflator housing in the initial stage, we can see a flow pattern of broken shock wave front and its downward propagation. The flow ejecting from the inflator housing was found to have large velocity fluctuations and the maximum velocity was about 700m/s. The velocity of high-speed flow was decreased rapidly and the duration of high-speed flow over 400m/s was maintained only to 30ms. After 100ms, there was no perceptible flow.

• 한국자동차공학회논문집
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• 제8권3호
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• pp.163-170
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• 2000

Accident statistics shows that the portion of fatal occupant injuries due to side impacts is considerably high. The side impact usually leads to a severe intrusion of side structure into the passenger compartment. Furthermore, the safety zone for the side impact is relatively small compared to the front impact. Those kinds of physics for side impact frequently result in a fatal injury for the occupant. Therefore, NHTSA and EEVC are trying to intensify the regulation for the occupant protection against side impact. Both the regulation and recent market trends are asking for an installation of side airbag. There are several types of system configuration for side impact sensing. In this paper, we adopt the acceleration-based remote sensing method for the side airbag control system. We mainly focus on the development of hardware and crash discrimination algorithm of remote sensing unit. The crash discrimination algorithm needs fast decision of airbag firing especially for high-speed side impact such as FMVSS 214 and EEVC tests. It is also required to distinguish between low-speed fire and no-fire events. The algorithm should have a sufficient safety margin against any misuse situation such as hammer blow, door slam, etc. This paper introduces several firing criteria such as acceleration. velocity and energy criteria that use physical value proportional to crash severity. We have made a simulation program by using Matlab/Simulink to implement the proposed algorithm. We have conducted an algorithm calibration by using real crash data for 2,500cc vehicle. The crash performance obtained by the simulation was verified through a pulse injection method. It turned out that the results satisfied the system requirements well.

• 자동차안전학회지
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• 제10권1호
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• pp.20-26
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• 2018

The fatality of rollover accidents in motor vehicle crashes is high despite their low incidence. Through the investigation of a 12-passenger van rollover accident in which 10 passengers were involved, we intend to analyze the correlation between the severity of the injury and the position of the occupants. We collected accident information from medical records, interviews, photo-images of the damaged van, field surveys, and the results of the Korean New Car Assessment Program (KNCAP). Based on the occupants' position, we classified injury sites and estimated injury severity. Passenger injury severity was evaluated by trauma score calculation. The initiation type of the rollover accident was passenger side 'fall-over' and the Collision Deformation Classification (CDC) code for the damaged van was 00TDZO3. The crash of the van involved 10 passengers, with an average age of $16.3{\pm}4.2years$. Few of the occupants had fastened seat belts at the time of the incident, and there was no airbag installed. One patient sustained severe liver injury and another was diagnosed with a fracture of the right humerus. The most common injuries were at the upper extremities and the neck. The average of Injury Severity Score (ISS) was $4.8{\pm}5.9$, and the average ISS of right-seated, mid-seated and left-seated occupants was $7.5{\pm}9.3$, $1.5{\pm}0.7$, and $3.3{\pm}2.1$ respectively (p>0.05). In the rollover (to-passenger side) accident of occupant unfastened, the average ISS of right-seated occupants (near side) was higher, but there was no statistically significant difference.

• 한국자동차공학회논문집
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• 제22권6호
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• pp.1-8
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• 2014

Safety performance of a new car is evaluated through USNCAP and their results in the star rating are provided to the consumers. It is very important to obtain high score of USNCAP to appeal their performance to consumers. Therefore the car companies have made the effort to improve their car safety performance. These efforts should satisfy the demand not only to get high score but also to pass the FMVSS, NHTSA regulations on safety. Huge numbers of car crash tests have been conducted on these bases by car companies. However physical tests spend too much cost and time, as an alternative way, the simulation on the car crash could be a solution to reduce the cost and time. Therefore the simulations have been widely conducted in car industry and various researches on this have been reported. In this study, restraint system had been optimized to minimize the injury of female passenger. Belted $5^{th}%ile$ female frontal crash test was selected from various test methods of USNCAP for the study. Initial velocity of the test was 56km/h. The combination injury probability of USNCAP was selected as an objective function and the injury limit value, which was defined in FMVSS, was set to an optimization constraint. Many researches that were similar to this study had been conducted, however most of them had limitation that interaction between airbag and safety belt had not been considered. Contrary to these researches, the interaction was considered in this study.

• 자동차안전학회지
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• 제15권4호
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• pp.95-101
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• 2023

As the popularization of autonomous vehicles is anticipated, it is expected that the variety of passenger postures will diversify. However, the current vehicle safety system is expected to be inadequate for accommodating these diverse passenger postures, particularly in reclined positions where severe injuries have been reported in frontal collisions. Therefore, it is necessary to investigate the biomechanical responses and tolerances of occupants in reclined postures. In this study, the behavior and injuries of a Hybrid-III dummy model in a reclined position are analyzed through frontal collision sled simulations equipped with the semi-rigid seat provided by the previous study, three-point safety belt with pretensioner and load limiter, and airbag models. The results are evaluated by comparing thouse reponses with post-mortem human surrogate (PMHS) data, and the findings are expected to be applicable to the basic design of a new restraint system suitable for various postures in autonomous vehicles.

• International Journal of Automotive Technology
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• 제7권7호
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• pp.769-776
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• 2006

A mathematical model is developed in this paper to define the interaction between the occupant and vehicle passenger compartment and to predict the occupant dynamic response during a sudden impulse load. Two different types of occupants are considered in this study, child and adult occupants. The occupants are considered as lumped masses connected to the child seat and vehicle's body masses by means of restraint systems. In addition, the occupant restraint characteristics of seat belt and airbag are represented by stiffness and damping elements. To obtain the dynamic response of the occupant, the equations of motion of the occupants during vehicle collisions are developed and analytically solved. The occupant's acceleration and relative displacement are used as injury criteria to interpret the results. It is demonstrated from the numerical simulations that the dynamic response and injury criteria are easily captured and analyzed. It is also shown that the mathematical models are flexible, useful in optimization studies and it can be used at initial design stage.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.903-908
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• 2007

A retractor is the major component of a seatbelt system that restraints passengers by locking the movement of webbing. Recently, in order to increase the effectiveness of seatbelt systems, motorized retractors that remove slack and correct passenger posture just before airbag expansion when collision is predicted are widely used. Key component of motorized retractors is the one-way clutch that engages and disengages the winding action of webbing according to the direction of motor revolution. Analytical investigation of action of the one-way clutch mechanism has been carried out to figure out conditions for one-way locking, and to study the effect of various kinematic and dynamic design variables of one-way clutch. Using combination of ADAMS and LifeMOD soft-wares, dynamic simulation of operation of motorized retractors including Hybrid-III dummy model has been carried out to evaluate the performance of the motorized retractors in various crash scenarios.

• 한국자동차공학회논문집
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• 제24권4호
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• pp.487-494
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• 2016

In order to comply with the Federal Motor Vehicle Safety Standard(FMVSS) No. 208 that has been in force since September 2003, an automatic airbag suppression system has become an essential option for detecting and protecting infants and children seated in the front passenger seat of vehicles in the U.S. market. MOBIS has developed the world's first weight-based OCS under the name NWCS. NWCS is composed of two sensors and ECU. It is sub-packaged in order to minimize the seat structure deviation. In this paper, technical features, robustness and performance of NWCS are summarized and discussed.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.571-577
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• 2006

This paper deals with dynamic tensile characteristics for the polypropylene used in an IP(Instrument Panel). The polypropylene is adopted in the dash board of a car, especially PAB(Passenger Air Bag) module. Its dynamic tensile characteristics are important because the PAB module undergoes high speed deformation during the airbag expansion. Since the operating temperature of a car varies from $-40^{\circ}C$ to $90^{\circ}C$ according to the specification, the dynamic tensile tests are performed at a low temperature($-30^{\circ}C$), the room temperature($21^{\circ}C$) and a high temperature($85^{\circ}C$). The tensile tests are carried out at strain rates of six intervals ranged from 0.001/sec to 100/sec in order to obtain the strain rate sensitivity. The flow stress decreases at the high temperature while the strain rate sensitivity increases. Tensile tests of polymers are rather tricky since polymer does not elongate uniformly right after the onset of yielding unlike the conventional steel. A new method is suggested to obtain the stress-strain curve accurately. A true stress-strain curve was estimated from modification of the nominal stress-strain curves obtained from the experiment. The modification was carried out with the help of an optimization scheme accompanied with finite element analysis of the tensile test with a special specimen. The optimization method provided excellent true stress-strain curves by enforcing the load response coincident with the experimental result. The material properties obtained from this paper will be useful to simulate the airbag expansion at the normal and harsh operating conditions.

• International Journal of Automotive Technology
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• 제7권7호
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• pp.827-832
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• 2006

Occupant classification and position detection have been significant research areas in intelligent safety systems in the automotive field. The detection and classification of seat occupancy open up new ways to control the safety system. This paper deals with a novel algorithm development, hardware implementation and testing of a prototype intelligent safety system for occupant classification and position detection for in-vehicle environment. Borland C++ program is used to develop the novel algorithm interface between the sensor and data acquisition system. MEMS strain gauge hermatic pressure sensor containing micromachined integrated circuits is installed inside the passenger seat. The analog output of the sensor is connected with a connector to a PCI-9111 DG data acquisition card for occupancy detection, classification and position detection. The algorithm greatly improves the detection of whether an occupant is present or absent, and the classification of either adult, child or non-human object is determined from weights using the sensor. A simple computation algorithm provides the determination of the occupant's appropriate position using centroidal calculation. A real time operation is achieved with the system. The experimental results demonstrate that the performance of the implemented prototype is robust for occupant classification and position detection. This research may be applied in intelligent airbag design for efficient deployment.