• 자동차안전학회지
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• 제10권2호
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• pp.6-12
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• 2018

Optimized section shape of aluminum bumper backbeam for enhancing the front high speed crashworthiness was investigated. Front body analysis model of a convertible vehicle was built up and parameter studies were carried out with changing the inner rib shape and the section thickness distribution. First an inner rib shape displaying most efficient structural performance was selected. Next, for the selected section the effect of section thickness combination was examined. Also, a light weighed backbeam section displaying crash performance over the current design was suggested. Finally RCAR front low speed impact analyses were carried out for the optimized models.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1213-1220
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• 2008

In this study, the crashworthy design guidelines for the high speed EMU were derived and numerically evaluated. As for this high speed train, there are several different features from the KTX in that the conventional type bogies are adopted and the front end car (TC car) accommodates passengers. It is natural that the impact acceleration of the front end car should be controlled under the appropriate level stipulated at safety regulations for collision accidents. Also, car-to-car interfacing structures and devices should be deliberately designed to prevent overriding and telescoping mechanisms. As the first step for these design countermeasures, it was studied that how much impact energy should be absorbed at the energy absorbing zones and devices of each carbody to satisfy the impact acceleration regulations of the safety regulations. These results will be used as the crashworthy design guidelines for the high speed train in the next year research.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.8-15
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• 2013

Wide range frequency pulses occur in a car crash test. Until now, low frequency under 400Hz has been used to determine an airbag deployment criteria. Also, FIS (Front Impact Sensor) has been used to detect the crash pulse in early stage. Nowadays, technology to determine an airbag delpoyment criteria by using a high frequency crash pulse without FIS is being focused on. In this paper, the signal transmissibility of high frequency pulse for two different cars was studied. Also, signal transfer test of high frequency pulse was done by using a high speed ball impact. Signal runtime of the frontal impact is compared with that of the side impact. The signal transmissibility difference due to the car structure difference was discussed and structure change for improving the signal transmissibility was proposed.

• 한국가시화정보학회지
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• 제9권1호
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• pp.55-60
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• 2011

Pulsed supersonic liquid jets injected into an ambient air are empirically studied by using a high pressure ballistic range system. Ballistic range systems which are configured with high-pressure tube, pump tube, launch tube and liquid storage nozzle. Experimental studies are conducted to use with various impact nozzle geometry. Supersonic liquid jets are generated by an impact of high speed of the projectile. High speed liquid jets are injected with M = 3.2 which pressure is 1.19 GPa. Multiple jets which accompany with shock wave and pressure wave in front of the jet were observed. The shock-wave affects significantly atomization process for each spray droplets. As decreasing orifice diameter, the averaged SMD of spray jets had the decreasing tendency.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권3호
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• pp.300-311
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• 2016

The analog-to-digital-converter-based (ADC-based) backplane receivers that consist of a front-end ADC followed by a digital equalizer are gaining more popularity in recent years, as they support more sophisticated equalization required for high data rates, scale better with fabrication technology, and are more immune to PVT variations. Unfortunately, designing an ADC-based receiver that meets tight power and performance budgets of high-speed backplane link systems is non-trivial as both front-end ADC and digital equalizer can be power consuming and complex when running at high speed. This paper reviews the state of art designs for the front-end ADC and digital equalizers to suggest implementation choices that can achieve high speed while maintaining low power consumption and complexity. Design-space exploration using system-level models of the ADC-based receiver allows through analysis on the impact of design parameters, providing useful information in optimizing the power and performance of the receiver at the early stage of design. The system-level simulation results with newer device parameters reveal that, although the power consumption of the ADC-based receiver may not comparable to the receivers with analog equalizers yet, they will become more attractive as the fabrication technology continues to scale as power consumption of digital equalizer scales well with process.

• 디지털융복합연구
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• 제16권9호
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• pp.173-178
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• 2018

에어백이 작동되는 중고속 추돌 사고의 경우 에어백 작동 전후의 차량 데이터가 차량의 EDM(Event Driven Memory)에 저장되어 그 추돌 속도를 쉽게 알 수 있다. 하지만 에어백이 작동하지 않는 저속영역에서 추돌하는 경우 그 속도를 산정하기가 어렵다. 또한 저속이라 하더라도 추돌속도에 따라 운전자의 부상 정도가 크게 영향을 받기 때문에 그 속도의 산정이 중요하다. 본 연구에서는 블랙박스에 저장된 영상 이미지를 분석하여 저속영역의 추돌속도를 연산하는 알고리즘을 제안하였다. 전기모터로 와이어로프를 이용하여 차량을 견인하는 방식으로 저속의 후방추돌 상황을 정확하게 재현하면서 다양한 차종과 속도에 대해 실험을 수행하였다. 이 때 블랙박스의 영상 이미지에서 두 차량의 거리가 좁아지는 비율과 전방 차량의 번호판 길이가 증가하는 비율이 동일함을 이용하여 추돌속도를 정밀하게 계산할 수 있다. 즉, 미리 측정된 초기거리와 블랙박스의 영상에서의 번호판의 길이를 초기조건으로 설정하여 본 연구의 계산 알고리즘을 적용하면 저속 추돌 속도를 정확하게 산정할 수 있다. 직선 추돌사고에는 본 연구의 결과가 그대로 적용되지만 각도를 두고 추돌하는 경우에는 별도의 고려가 필요하다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.235-242
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• 2000

The most important technology to improve crashworthiness of high speed trains is to design their front structures to absorb crash energy easily. In this paper, crashworthy designs of the front structures in KTX and KHST are compared by numerical simulation under SNCF accident scenario. Furthermore, to evaluate their crashworthiness tinder a typical real situation, the power cars are simulated for the accident collided against a deformable dump truck of 15 tons at 110 kph. The front structure of KHST, finally designed, shows a good crashworthy characteristics. Finally, the impact strength of coupling components is evaluated by analyzing a consist of the front three KHST units under scenario of train-to-train collision at 30 kph.

• 한국운동역학회지
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• 제13권1호
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• pp.173-184
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• 2003

The purpose of this study was to investigate the batting characteristics in elite baseball players. Seven skilled collegiate players hit the ball which was thrown by a pitching machine linearly and strongly to the center of the field. Time, velocity, angle and pound reaction force variables were measured by using high-speed video cameras and pound reaction force analyzer. The results were as follows: 1. The elite players finished their stride performance in a short time and they stayed longer in a swing phase. The increases in the range of trunk rotation were associated with the delay of the swing phase. 2. The 'take-back' phenomenon in the trunk was showed after the stride phase. 3. The down swing demonstrated powerful line drives. 4. Equivalent body weights were placed on both feet during the ready phase. 95% of the body weights were moved to the rear foot during the stride phase, whereas the body weights were driven to the front foot during the swing phase. 95% of the body weights were placed on the front foot at impact.

• 한국철도학회논문집
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• 제6권1호
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• pp.15-20
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• 2003

The computer simulation techniques were adopted to evaluate the effects of seating positions of passenger under various accident scenarios. The baseline of computer simulation model was tuned by the sled impact tests which conducted under the upright and standard seating positions. This study shows the effect of relative velocity between occupant and struck vehicle while occupant is impacted to a front seat's seatback. Although, base on the current accident scenarios, The KHST is performed well enough to protect average adult male occupants. However, Results from the tests indicate small size occupant or higher impact speed may cause sever neck and femur injuries.

• International Journal of Automotive Technology
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• 제5권4호
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• pp.221-238
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• 2004

Wall interactions of direct injection spray were investigated using laser-sheet imaging, shadowgraphy, wetted footprint and phase Doppler interferometry techniques. A narrow-cone high-pressure swirl injector is used to inject iso-octane fuel onto a plate, which has three different impact angles inside a pressurized chamber. Heated air and plate conditions were compared with unheated cases. Injection interval was also varied in the heated case to compare dry- and wet- wall impingement behaviors. High-speed macroscopic Mie-scattering images showed that presence of wall and air temperature has only minor effect on the bulk spray structure and penetration speed for the narrow-cone injector tested. The overall bulk motions of the spray plume and its spatial position at a given time are basically unaffected until a few millimeters before impacting the wall. The surface properties of the impact surface, such as the temperature, the presence of a preexisting liquid film also have a small effect on the amount of wetting or the wetted footprint; however, they have strong influence on what occurs just after impact or after a film is formed. The shadowgraph in particular shows that the plate temperature has a significant effect on vapor phase propagation. Generally, 10-20% faster horizontal vapor phase propagation is observed along the wall at elevated temperature condition. For impingement onto a preexisting film, more splash and evaporation were also observed. Contrary to some preconceptions, there is no significant splashing and droplet rebounding from surfaces that are interposed in the path of the DI gasoline spray, especially for the oblique impact angle cases. There also appears to be a dense spray front consists of large sac spray droplets in the oblique impact angle cases. The bulk of the spray is not impacted on the surface, but rather is deflected by it The microscopic details as depicted by phase Doppler measurements show that the outcome of the droplet impaction events can be significantly influenced. Only droplets at the spray front have high enough Weber numbers for wall impact to wet, splash or rebound. Using the sign of vertical velocity, the time-resolved downward droplets and upward droplets are compared. The Weber number of upward moving droplets, which seldom exceeds unity, also decreases as the impact angle decreases, as the droplets tend to impact less and move along the wall in the deflected spray plume.