• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.3
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• pp.66-73
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• 2013

This study assesses neck injury of occupants in a real traffic accident case that a preceding vehicle moved backward and impacted a parked vehicle at a low velocity. This case is different from a case of whiplash injury caused by rear impact on vehicle. The impact velocity was estimated from damages of the two vehicle bumpers and the displacement of the parked vehicle was also estimated from CCTV images. MADYMO simulation was performed based on the vehicle specifications and investigation report. The comparison of neck flexion moments with the corresponding injury criteria revealed that occupants of the parked vehicle might have hardly neck injury.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.315-318
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• 2007

최근 자동차안전기준이 중요시되면서 안전에 대한 관심이 높아지고 있다. 본 연구는 FMVSS301 및 자동차안전기준 제 91조에 해당하는 시험조건으로 후방추돌시 인체상해를 방지하기위해 뎀퍼가 장착된 자동차시트의 메카니즘을 설계 및 해석을 하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.787-793
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• 2002

In this study, a bar impact test of low velocity was carried out to gain an insight into the damage mechanism and sequence induced in alumina plates(AD 85 and AD 90) under impact conditions. An experimental setup utilizing an instrumented long bar impact was devised, that can measure directly the impact force applied to the specimen and supply a compressive contact pressure to the specimen. During the bar impact testing, the influences of the contact pressure applied along the impact direction to the specimen on the fracture behavior were investigated. The measured impact force profiles explained well the damage behavior induced in alumina plates. The higher contact pressure to the specimen led to the less damage due to the suppression of radial cracks due to the increase in the apparent flexural stiffness of plate. It had produced the change of damage pattern developed in the specimen; from the radial cracks to the local contact stress dominant damage. It would contribute to the improvement of the ballistic property in ceramic plates. The observed results showed the following sequence in damage developed: The development of cone crack at impact region, the formation of radial cracks from the rear surface of plate depending on the plate thickness, the occurrence of crushing within the cone envelope and the fragmentation.

• Current Photovoltaic Research
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• v.7 no.4
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• pp.97-102
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• 2019

Bifacial and semitransparent hydrogenated amorphous silicon (a-Si:H) thin-film solar cells in p-i-n configuration were prepared with front and rear transparent conducting oxide (TCO) electrodes using plasma-enhanced chemical vapor deposition method. Fluorine-doped tin oxide and tin-doped indium oxide films were used as front and rear TCO contacts, respectively. Film thickness of intrinsic a-Si:H absorber layers were controlled from 150 nm to 450 nm by changing deposition time. The dependence of performance characteristics of solar cells on the front and rear illumination direction were investigated. For front illumination, gradual increase in the short-circuit current density (J_SC) from 10.59 mA/㎠ to 14.19 mA/㎠ was obtained, whereas slight decreases from 0.83 V to 0.81 V for the open-circuit voltage (V_OC) and from 68.43% to 65.75% for fill factor (FF) were observed. The average optical transmittance in the wavelength region of 380 ~ 780 nm of the solar cells decreased gradually from 22.76% to 15.67% as the absorber thickness was changed from 150 nm to 450 nm. In case of the solar cells under rear illumination condition, the J_SC increased from 10.81 to 12.64 mA/㎠ and the FF deceased from 66.63% to 61.85%, while the V_OC values were maintained at 0.80 V with increasing the absorber thickness from 150 nm to 450 nm. By optimizing the deposition parameters, a high-quality bifacial and semitransparent a-Si:H solar cell with 350 nm-thick i-a-Si:H absorber layer exhibited the conversion efficiencies of 7.69% for front illumination and 6.40% for rear illumination, and average visible optical transmittance of 17.20%.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.111-122
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• 2002

European offset impact analysis of an electric vehicle was done using the robust design method. Section properties of some of the vehicle structure components which influence the european offset impact characteristics were chosen as the main factors fur the design. Eight factors were considered for the analysis: one with two level and seven with three level combinations comprising the L$\_$18/(2$^1$$\times$3$\^$7/) orthogonal array. It is shown that the sensitivities of the factors and the best combination of the factors can be obtained. One of the noteworthy results is that the design with the lower stiffness of the front components of engine room than the rear components can absorb more crash energy. Also it is shown that there exist interactions between some of factors considered.

• Korean Journal of Applied Biomechanics
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• v.13 no.1
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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.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.1-10
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• 2008

This study analyzed the rear foot angle of the supporting leg and the anatomical rotation angle of the kicking angle in soccer instep kick and drew conclusions as follows. When the supporting leg was landing on the ground, the valgus angle of the ankle joint reached the maximum peak, and plantar flexion was slightly different in the timing of the maximum peak between the two groups. The flexion angle of the rear foot was statistically significantly different between the two groups, and the movement of the crus on the landing of the supporting foot did not show a statistically significant difference between the groups. The crus leaned backward most before the impact, and the side to side gradient of the crus on impact was $22^{\circ}$. The flexion/extension of the hip joint of the kicking leg reached the maximum peak when the supporting foot was landing on the ground, and at the moment, the maximum extension angle of the hip joint was over $30^{\circ}$. The flexion angle of the knee joint of the kicking leg was largest after landing. While the maximum plantar flexion angle and maximum valgus angle of the ankle joint were not significantly different between the two groups, the maximum external rotation angle was significantly different.

• Journal of the Korea Convergence Society
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• v.9 no.8
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• pp.179-184
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• 2018

The driving methods of car are front wheel drive, rear wheel drive and four wheel drive. At driving methods, constant velocity joint is the most important part at carrying out two functions for converting to the direction which the driver wants and transferring the power to wheels. At driving on the road, the impact can be applied to the parts transmitting power according to the state of road surface. In this study, each models of three constant velocity joints whose shaft length are different respectively were modelled with CATIA and the structural and fatigue analyses were carried out by using ANSYS. This study result is thought to be the useful material at designing the constant velocity joint with the durability against impact. And it is possible to be grafted onto the convergence technique at the design of constant velocity joint and show the esthetic sense.

• Journal of the Korean Society of Safety
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• v.23 no.2
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• pp.72-80
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• 2008

In a case of an automobile collision, vehicle damage and injury of the driver and the passenger occur. The scale of the collision which is effected by the extent of vehicle damage and the injury of the passenger, depends on the delta-V. Based on the photograph interpretation o the actual case of accidents in the Seoul and the Incheon area, this study measured the depth of crush and calculated the delta-V. Through verifying the correlation of the depth of crush and the change of velocity, relative equation was evaluated and compared with the prior study results to prove that they are almost identical. Thus, the depth of crush can be used as an index of the degree of impact, which can be utilized as the change of velocity to evaluate the level of injury done to the passengers. However, the period of hospitalization and diagnostics claimed by the injured proves to have no correlation with the delta-V and the extent of vehicle damage, this is due to the non-objective way of diagnosis and the anamnesis of the injured. This study established the absolute limit harmlessness and the choosing limit harmlessness, allowing the appraisal for Yes or No of the injury or the harmlessness based on the prior studies. Moreover, utilizing the relative equation formed between the depth of crush and the delta-V, each case of collision was compared and evaluated in comparison to the limit harmlessness to prove that the 90.4% of the so-called 'claiming-to-be-injured' were exaggerating or fabricating.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.141-150
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• 2017

A rapid increase in traffic accidents involving senior vehicle occupants has been an issue in Korea because of the aging of the population occurring at one of the fastest rates in the world; unfortunately, few studies beyond several looking at the effect of senior occupants on the level of accident injury severity can be found in the literature. A Multinomial logit model was estimated with Newton-Raphson algorithm to perform bias-reducing penalized likelihood optimization. Model covariates integral to developing the model were included, but the main focus was on the interaction of seating position and injury to senior vehicle occupants. It was found that the likelihood of an accident resulting in a fatality increased: 2.2 times for the driver seat, 2.7 times for the front passenger seat, and even 6.7 times for the rear seat. A mandatory seatbelt law to be extended to the rear seat needs to pass the assembly as soon as possible, and government, industry, and safety groups should be encouraged to join forces to strongly carry out targeted campaigns for the wearing of seatbelts in all vehicle seats to enhance the safety of senior occupants as well as other occupants who are vulnerable to road traffic accidents.