• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.138-144
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• 2004

Occupant protection in the side impact of a vehicle becomes one of the most important issues today. So, to reduce development time and cost, it needs test equipment which conducts an accurate simulation of the side impact crash. This paper describes a new test method for side impact, which utilizes a standard 12inch-HYGE-type sled facility. If a side impact sled test can simulate vehicle intrusion very well, it will contribute to develop full-scale side impact crash performance. The newly developed sled test method enables simulation for dummy motion, injury, door velocity, trim crack, and vehicle structure to be accurate. Ant also this sled test method can be applied to the development of side air-bag.

• Korean Journal of Applied Biomechanics
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• v.30 no.1
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• pp.37-49
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• 2020

Objective: The purpose of this study was to investigate the injury factors of Taekwondo jumping kick during landing phase according to the experience of injury and to suggest a stable landing movement applicable to free style Poomsae. Method: The participants were non-injury group (NG), n = 5, age: 20.5±0.9 years; height: 171.6±3.6 cm; body weight: 65.7±4.4 kg; career: 5.0±2.7 years. Injury group (IG), n = 9, age: 21.0±0.8 years; height: 170.9±4.6 cm; body weight: 67.1±7.0 kg; career: 8.6±5.0 years. The variables are impact force, loading rate, vertical stiffness, lower limb joint angle, stability, balance, and muscle activity in the landing phase. Results: NG was statistically larger than IG in the gluteus medius (p<.05). The impact force, loading rate and vertical stiffness decreased as the landing foot angle, the ROM of lower limb joint angle and COM displacement increased (p<.05). Conclusion: Based on the results, it means that the landing foot angle plays an important role in the impact reduction during landing phase. It is required the training to adjust the landing foot angle.

• Journal of Environmental Impact Assessment
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• v.18 no.6
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• pp.377-386
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• 2009

Due to severe flooding, the long-term residence of turbidity flows within the stratified Daecheong Reservoir have lengthened. A long-term residence of turbidity flows within the stratified Daecheong Reservoir after floods has been major environmental issue. The objective of this study was to assess the impact to water supply from the hydrodynamics and turbidity outflow. Two gate operation scenarios were investigated. Scenario A refers to gate operations according to rainfall events, and scenario B refers to gate operations according to inflow. From the results of secenario A, the SS concentrations decreased from 0.44mg/l to 0.54mg/l at the front of the dam, whereas SS concentrations increased from 0.24mg/l to 1.24mg/l at the intake points at Munhi and Daejeon. From the results of scenario B, the SS concentrations decreased from 0.61mg/l to 0.83mg/l at the front of Dam; howeve, SS concentrations also decreased from 0.16mg/l to 0.48mg/l at the intake points at Munhi and Daejeon. It seems that it may be more efficient to control turbidity by creating additional outflows of generated discharge after intensive rainfalls than not.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.500-509
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• 2015

The numerical simulation of two-dimensional moving blade row interactions is conducted by CFD means to investigate the interactions between the front and rear propeller in a stratospheric airship contra-rotating open propeller configuration caused by different rotational speeds. The rotational speed is a main factor to affect the propeller Reynolds number which impact the aerodynamic performance of blade rows significantly. This effect works until the Reynolds number reaches a high enough value beyond which the coefficients become independent. Additionally, the interference on the blade row has been revealed by the investigation. The front blade row moves in the induced-velocity field generated by the rear blade row and the aerodynamic coefficients are influenced when the rear blade row has fast RPMs. The rear blade row moving behind the front one is affected directly by the wake and eddies generated by the front blade row. The aerodynamic coefficients reduce when the front blade row has slow RPMs while increase when the front blade row moves faster than itself. But overall, the interference on the front blade row due to the rear blade row is slight and the interference on the rear blade row due to the front blade row is much more significant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5051-5059
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• 2015

Structural behaviour of the front loader for an agricultural tractor was analyzed for three impact test conditions: drop and catch, corner pull, and corner push. Rigid-body dynamic, transient structural, and static structural analyses were conducted using a commercial finite element software. Analysis of the drop and catch test dealt with the case that the bucket located at the maximum elevation was dropped and catched through three steps. Analysis of the corner pull test dealt with the case that the bucket constrained to the ground by a chain at its corner was raised suddenly. Analysis of the corner push test dealt with the case that the corner of the bucket collided with an obstacle. Results of analyses of the three test conditions showed that maximum stress occurs at the geometrically discontinuous location in the mount and is caused from local stress concentration. Results of the present research can be utilized as a guideline to achieve more reliable and safe structural design of the front loaders.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.99-106
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• 2013

Concrete materials subjected to impact by high velocity projectiles exhibit responses that differ from those when they are under static loading. Projectiles generate localized effects characterized by penetration of front, spalling of rear and perforation as well as more widespread crack propagation. The magnitude of damage depends on a variety of factors such as material properties of the projectile, impact velocity, the mass and geometry as well as the material properties of concrete specimen size and thickness, reinforcement materials type and method of the concrete target. In this study, penetration depth of front, spalling thickness of rear and effect of spalling suppression of concrete by fiber reinforcement was evaluated according to compressive strength of concrete. As a result, it was similar to results of the modified NDRC formula and US ACE formula that the more compressive strength is increased, the penetration depth of front is suppressed. On the other hand, the increase in compressive strength of concrete does not affect spalling of rear suppression. Spalling of rear is controlled by the increase of flexural, tensile strength and deformation capacity.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.177-182
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• 2003

The front-end side members of automobiles absorb most of the energy in a case of front-end collision. The front-end side members are required to have a high stiffness together with easiness to collapse sequentially to absorb more impact energy. The axial static collapse test (5mm/min) was conducted by using UTM for form different types of members which have different cross section shapes; single hat, single cap, double cap, and double hat. The single hat shaped section member has the typical standard section, which the double hat shape section has a symmetry in the center to have more stiffness. As a result of the test, the energy absorbing characteristic was analyzed for different section shapes. It turned out that the change of section shape influence the absorbing energy, the mean collapse load and the maximum collapse load, and the relation between the change of section shape and the collapse mode.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.402-408
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• 2021

Vehicle engineering analysis in the event of an accident caused by a car built on mechanical design has not been investigated in-depth but relies on the subjective experience knowledge of the investigator. This study analyzed the correlation between the speed, progress, steering, and braking before impact, which is consistent with the final stop position, by drawing a site situation chart using the CAD (CAD) program and repeating 250 crashes using the PC-Crash program. The following situations were investigated: lower impact velocity; greater impact speed of the vehicle, which is not affected significantly by the departure angle; higher vehicle speed, such as the effective impact velocity, after the impact; higher vehicle speed; and lower vehicle speed. (Ed note: I am unsure what you are saying here. It appears contradictory and not a complete sentence. Please check the changes.)The simulation results of this study identified the process of returning to the magnetic progression lane after recognizing the opposite porter while Mighty was carried out on the uphill left-curve section in a position that crossed the center line, and the collision of the porter's front left side, pushing the porter in the right diagonal direction and making the front stop towards approximately 11 o'clock.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.5
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• pp.195-201
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• 2000

The fundamental spot welded sections of automobiles (hat-shaped and double hat-shaped sections) absorb most of the energy in a front impact collision. The sections of various thickness, shape and weld width on the flange lave been tested on axial impact crush load (Mass 40kg, Velocity 7.19m/sec) using a vertical air pressure crash est device Characteristics of impact collapse have been reviewed and a structure of optimal energy absorbing capacity is suggested.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.103-113
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• 2015

This paper studies impact performance of wire-mesh and steel fiber-reinforced concrete based on high-velocity impact experiments using hard spherical balls. In this experimental study, panel specimens were tested with various parameters such as steel fiber volume fraction, presence/absence of wire mesh, panel thickness, impact velocity, and aggregate size for the comparison of impact resistance performance for each specimen. While improvement of the impact resistance for reducing the penetration depth is barely affected with steel fiber volume fraction, the impact resistance to scabbing and perforation is improved substantially. This was due to the fact that the steel fiber had bridging effects in concrete matrix. The wire mesh helped minimizing the crater diameter of front and back face and enhanced the impact resistance to scabbing and perforation; however, the wire mesh did not affect the penetration depth. The wire mesh also reduced the bending deformation of the specimen with wire mesh, though some specimens had splitting bond failure on the rear face. Additionally, use of 20 mm aggregates is superior to 8 mm aggregates in terms of penetration depth, but for reducing the crater diameter on front and back faces, the use of 8 mm aggregates would be more efficient.