• 소음진동
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• 제1권2호
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• pp.115-120
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• 1991

The impact hammer is extensively used in experimental modal analysis as a means to provide force over a broad range of frequencies. The hammer mass and the impact head are often changed to achieve a desired impact time duration with its corresponding input frequency spectrum, these mass changes affect the performance and sensitivity of the force transducer employed to measure the impact force. Both a mathematical model describing the effects of impact head and hammer mass on the performance of the force transducer and experimental verification of this model are presented here.

• 한국정밀공학회지
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• 제23권12호
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• pp.88-94
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• 2006

In this study, the dynamic impact analysis for the passenger air-bag(PAB) module has been carried out by using FEM to predict the dynamic characteristics of vehicle ride safety against head impact. The impact performance of vehicle air-bag is directly related to the design parameters of passenger air-bag module assembly, such as the tie bar bracket's width and thickness, respectively, However, the product's design of PAB module parameters are estimated through experimental trial and error according to the designer's experience, generally. Therefore, the dynamic analysis of head impact test of the passenger air-bag module assembly of automobile is needed to construct the analytical methodology At first, the FE models, which are consist of instrument panel, PAB Module, and head part, are combined to the whole module system. Then, impact analysis is carried out by the explicit solution procedure with assembled FE model. And the dynamic characteristics of the head impact are observed to prove the effectiveness of the proposed method by comparing with the experimental results. The better optimized impact performance characteristics is proposed by changing the tie bracket's width md thickness of module. The proposed approach of impact analysis will provides an efficient vehicle to improve the design quality and reduce the design period and cost. The results reported herein will provide a better understanding of the vehicle dynamic characteristics against head impact.

• 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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 추계학술대회 논문요약집
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• pp.16-16
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• 2003

In this study, for a safety assessment of wheelchair occupant in side impact, we used a dynamic sled impact test results. The test was carried out total 6 times and impact speed was 13g$\pm$0.43/28km/h$\pm$0.95, By using EURO SID-1 dummy, head performance criteria(HPC), abdominal peak force, etc. were measured. We evaluated wheelchair occupant safety by motion criteria(MC) which was measured by head, trunk and side deformation change of wheelchair and Head & Neck injury criteria(HNI) measured by using head and neck deformation angle and time relation. When we assumed that the maximum injury value in side impact was 100%, the results of motion criteria(MC) of wheelchair occupant were max 80.3, mim 32.3 and average 60.3%, Head & Neck injury criteria(HNI) value were max 118.4, min 14.5 and average 59.7%.

• 자동차안전학회지
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• 제13권3호
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• pp.60-68
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• 2021

Invisible passenger airbag door system of hard panel types must be designed with a weakened area such that the side airbag will deploy through the instrument panel as like intended manner, with no flying debris at any required operating temperature. At the same time, there must be no cracking or sharp edges in the head impact test. If the advanced airbag with the big difference between high and low deployment pressure ranges are applied to hard panel types of invisible passenger airbag (IPAB) door system, it becomes more difficult to optimize the tearseam strength for satisfying deployment and head impact performance simultaneously. It was introduced the 'Operating Window' idea from quality engineering to design the hard panel types of IPAB door system applied to the advanced airbag for optimal deployment and head impact performance. Zigzab airbag folding and 'n' type PAB mounting bracket were selected.

• International Journal of Aeronautical and Space Sciences
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• 제4권2호
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• pp.26-36
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• 2003

The objective of this study is to enhance neural-network guidance to consider the impact condition. The optimal impact condition in this study is defined as an head-on attack. Missile impact-angle error, which is a measure of the degree to which the missile is not steering for a head-on attack, can also have an influence on the final miss distance. Therefore midcourse guidance is used to navigate the missile, reducing the deviation angle from head on, given some constraints on the missile g performance. A coordinate transformation is introduced to simplify the three-dimensional guidance law and, consequently, to reduce training data. Computer simulation results show that the neural-network guidance law with the coordinate transformation reduces impact-angle errors effectively.

• 한국인터넷방송통신학회논문지
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• 제16권3호
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• pp.179-186
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• 2016

본 연구는 차량의 도로이탈을 방지하고, 충격량을 흡수하여 차량 탑승자 및 도로주변의 인도를 횡단하는 보행자를 보호하기 위한 차량용 방호울타리에 관한 연구로서 LS-DYNA를 이용해 탑승자 보호성능 평가시험을 시뮬레이션하였으며, 다양한 속도와 각도를 변경하여 반복 시뮬레이션을 하여 충돌조건에 따른 탑승자 보호성능을 고찰하였다. 시뮬레이션을 위한 변수의 설정은 국내차량 판매대수에 따른 평균차량의 중량을 구하고, 미국 NHTSA의 NASS를 분석하여 실제 사고가 발생하는 속도와 충돌각도구간을 검출하였다. 그 결과로 충돌속도와 충돌각도가 커질수록 THIV(탑승자 충격속도)와 PHD(탑승자 가속도) 값이 증가하는 것을 확인하였으며, 차량이 가드레일의 지주에 걸리는 현상이 발생할 때 탑승자보호성능이 크게 저하되는 것을 확인하였다.

• 한국안전학회지
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• 제33권5호
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• pp.120-126
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• 2018

The traffic accident types are largely classified into vehicle to vehicle accident, vehicle-to-person accident and single-vehicle. Especially, the single-vehicle accident types are severe when the vehicle crashed into road facilities such as bridge, piers, utility poles. The severity of single-vehicle accidents are ten times higher than that of all other accidents types. It is needed to consider to reduce accident severity. This study was conducted to develop crash worthy safety design facility to ensure the vehicle occupant safety. The simulation and the crash tests were conducted for assessment of the safety performance to check the criteria of CC2(Crash Cushion 2) level. THIV(Theoretical Head Impact Velocity) and PHD(Post-impact Head Deceleration) were used to assess occupant impact severity for crashes. The non-redirection collision test conditions for 900 kg and 1,300 kg-head on crash tests, 900 kg-1/4 offset crash tests, 1,300 kg-head on crash test with $15^{\circ}$angle were conducted. The simulation and experiment test result showed that THIV values were below 44 km/h criterion, PHD values were below the 20G. The development non-redirective crash cushion is expected to be used for the fixed object such as bridge piers for assuring occupant safety.

• Structural Engineering and Mechanics
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• 제48권5호
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• pp.661-679
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• 2013

In this work, the safety performance of a commercial motorcycle helmet already placed on the market is assessed. The assessed motorcycle helmet is currently homologated by several relevant motorcycle standards. Impacts including translational and rotational motions are accurately simulated through a finite element numerical framework. The developed model was validated against experimental results: firstly, a validation concerning the constitutive model for the expanded polystyrene, the material responsible for energy absorption during impact; secondly, a validation regarding the acceleration measured at the headform's centre of gravity during the linear impacts defined in the ECE R22.05 standard. Both were successfully validated. After model validation, an oblique impact was simulated and the results were compared against head injury thresholds in order to predict the resultant head injuries. From this comparison, it was concluded that brain injuries such as concussion and diffuse axonal injury may occur even with a helmet certified by the majority of the motorcycle helmet standards. Unfortunately, these standards currently do not contemplate rotational components of acceleration. Conclusion points out to a strong recommendation on the necessity of including rotational motion in forthcoming motorcycle helmet standards and improving the current test procedures and head injury criteria used by the standards, to improve the safety between the motorcyclists.

• 한국안전학회지
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• 제27권5호
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• pp.30-34
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• 2012

A safety helmet is a personal protective equipment to protect the head from falling and flying objects. A safety helmet has the maximum delivered impact force as shock absorption performance, the lower delivered impact force the better performance, which was not a controlled variety during manufacturing safety helmet. Accordingly there were some difficulties in establishing the standard for improved performance as there was not a clear controllable impact force for improved performance. In this study the shock absorption performance was intended to be found as coefficient of restitution related to impulse. As a research method, a coefficient of restitution during the absorption of shock was calculated using the impulse transferred to pharynx utilizing the safety helmet shock absorption performance testing device based on the theory of momentum and impulse. The estimated impulsive force curve was derived assuming that shock was not absorbed using the measured data. The sample was selected as tested goods of ABS material for safety certification available mainly in the market. As a result of study, the maximum delivered impact force of safety helmet made by a domestic safety certified a company was 735 N, and its coefficient of restitution proved to be 0.64. The smaller coefficient of restitution is, the lower maximum delivered impact force and the higher shock absorption performance. The coefficient of restitution can be used as a performance index of safety helmet.