PURPOSES : The purpose of this study is to investigate the correlation between occupant impact velocities and occupant injury indices under the restraint of an airbag and a seat belt, during frontal crash events. METHODS : The frontal crash test data of 93 tests conducted according to the Korea New Car Assessment Program (KNCAP) were investigated. The test data was measured by using a dummy to obtain occupant injury indices for the head, chest, neck, and upper legs. Occupant impact velocities (OIVx and OIVz) were calculated from the head acceleration of the test dummy. Pearson's correlation analysis and regression analysis were used to investigate the correlation between occupant impact velocities and occupant injury indices. In addition, the occupant impact velocities at the center of gravity of a vehicle, obtained by using the accelerations measured at the test vehicle's B-pillars, were investigated. RESULTS: The OIVx threshold obtained from the test dummies, which corresponds to the HIC15 of 700, was 70 km/h for a sedan, and 72 km/h for an SUV, which is significantly higher than the occupant impact velocity of 44 km/h, the limit of the domestic guideline on “Installation and management guide for roadside safety facilities”. This difference can be attributed to the influence of the air bags and seat belts. Additionally, the OIVx threshold obtained from the center of gravity of the vehicle corresponding to the HIC15 of 700 was approximately 72 km/h. CONCLUSIONS: Occupant safety performance criteria for the condition that airbags operate and seat belts are restrained, are required for the frontal impact tests of road safety facilities using a collision velocity of 60 km/h or higher.

저장조에 위치한 사용후핵연료는 가혹한 원자로 조건에 의해 구조적 건전성이 와해되므로 외력에 취약하다. 따라서 운반 및 취급 중 사고 상황이 고려되어야 한다. 극단적인 경우, 핵연료 취급 중 사고로 인해 핵연료 저장조에서 핵연료집합체 낙하 가 발생할 수 있다. 이러한 사고 상황 하에서 연료봉 파손 등을 평가하기 위해서 수조에 충돌할 때 발생하는 충돌력을 분석 할 필요가 있다. 이는 핵연료가 수조 바닥에 충돌할 때의 속도를 입력으로 하여 평가될 수 있다. 연료봉이 핵연료 중량 및 부 피의 대부분을 차지하고 있으므로, 연료봉 다발은 수중 항력을 예측하는데 중요한 역할을 한다고 볼 수 있다. 본 연구에서는 3×3 의 짧은 연료봉 다발을 모델로 사용하여 수중에서 낙하할 때 받는 수력을 계산하였고, 이를 전산모사와의 비교를 통하 여 검증하였다. 본 방법론을 사용후핵연료 건전성 평가에 적용할 수 있을 것으로 기대된다.

Dynamic plastic deformation behavior of copper particles occurred during the cold spray processing was numerically analyzed using the finite element method. The study was to investigate the impact as well as the heat transfer phenomena, happened due to collision of the copper particle of in diameter with various initial velocities of into the copper matrix. Effective strain, temperature and their distribution were investigated for adiabatic strain and the accompanying adiabatic shear localization at the particle/substrate interface.

Objectives: The purpose of this study was to investigate the effects of wheelchair propulsion speed changes on the shoulder impingement syndrome. Method: EMG activity of 5 muscles (biceps brachii, pectoralis major, deltoid anterior, triceps brachii, and trapezius) were recorded with surface electrodes in 24 males during propulsion of three different speed levels on a motor-driven wheelchair treadmill. EMG signal was analysed using root mean square (RMS) values. In order to assure the statistical significance of the results, the one-way ANOVA and a Post Hoc Multiple Comparison were applied at the 0.05 level of significance. Results: The results of this study were as follows: Biceps brachii, and pectoralis RMS value variations of wheelchair propulsion speed between 45m/min and 60m/min, and between 60m/min and 75m/min were not statistically different (p>0.05). Triceps brachii, deltoid anterior and trapezius RMS value variations of wheelchair propulsion speed between 45m/min and 75m/min were statistically different (p<0.05). Conclusions: The risk of impingement syndrome has increased from deltoid muscle contraction growth and trapezoid, triceps brachial muscle endurance decrease when wheelchair propulsion speed rises. To prevent from impingement syndrome wheelchair users should strengthen and endure shoulder muscles. Besides we need education on propulsion posture and suitable position for wheelchair users.

Impact Severity is important parameter to design concrete barrier in South Korea. However, maximum load and load-time history graph showed different depending on parameters under vehicle impact loading. Therefore, in this study, analysis according was conducted to various impact conditions such as vehicle mass and impact velocity under same impact severity. Obtained results from load-time history graph showed key parameter is velocity compared to vehicle mass.

Human-robot co-operation becomes increasingly frequent due to the widespread use of service robots. However, during such co-operation, robots have a high chance of colliding with humans, which may result in serious injury. Thus, many solutions were proposed to ensure collision safety, and among them, collision detection algorithms are regarded as one of the most practical solutions. They allow a robot to quickly detect a collision so that the robot can perform a proper reaction to minimize the impact. However, conventional collision detection algorithms required the precise model of a robot, which is difficult to obtain and is subjected to change. Also, expensive sensors, such as torque sensors, are often required. In this study, we propose a novel collision detection algorithm which only requires motor encoders. It detects collisions by monitoring the high-pass filtered version of the velocity error. The proposed algorithm can be easily implemented to any robots, and its performance was verified through various tests.