• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.92-93
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• 2013

In this study, Shock Absorption performance of Magneto-rheological elastomer(MRE) is identified through the drop impact test. Magneto-rheological materials are divided into two groups by MR fluid in fluid state and MR elastomer in solid state like rubber. The stiffness characteristics of Magneto-rheological material can be changed as magnetic field is applied. The impact loads in MR elastomer were measured under weight of impactor. Experiment results are shown through the experiments to confirm the effect of shock absorption of MR elastomer. Thus, the MR elastomer can be applied to shock absorber used in area that shock occurs.

• International Journal of Ocean System Engineering
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• v.2 no.2
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• pp.92-96
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• 2012

This study presents a rockfall impact analysis of a typical roadway. Dynamic finite element analyses using ANSYS AUTODYN are conducted to determine the effect of the drop heights (5 m, 10 m) on the damage to a roadway model. The Rockfall is modeled as a spherical shape with a weight of 400 kg, and each drop height is converted to a corresponding impact velocity to save computational time. The roadway model is comprised of an asphalt layer, base layer, sub-base layer, and sub-grade layer. In this paper, the asphalt is modeled using a linear elastic model. The base layer, sub-base layer, and sub-grade layer are modeled using a Mohr-Coulomb model. From the analyses, the effects of the drop height on the damages and stresses are examined and discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.659-660
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• 2008

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.163.2-163.2
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• 2005

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1255-1256
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• 2010

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.12
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• pp.1229-1235
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• 2008

ELT(emergency locator transmitter) has assisted in the rescue of thousands of lives in distress. Aviators, mariners and land users being equipped with distress beacons are capable of transmitting distress signals to the satellites in emergency situations anywhere in the world. In this paper, Drop/Impact simulation was performed for ELT Body-case. FE model for Body-case was constructed with MSC/Dytran and refined using the Karas example simulation for Body-case prototype. Shock/impact survivability analysis was performed for ELT operations. FE model constructed with MSC/Nastran. Transient response analysis for refined ELT model was perfomed for ELT under impact shock loading condition.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.2
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• pp.133-149
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• 2022

The design of a wooden impact limiter equipped to a transportation cask for radioactive materials was optimized. According to International Atomic Energy Agency Safety Standards, 9 m drop tests should be performed on the transportation cask to evaluate its structural integrity in a hypothetical accident condition. For impact resistance, the size of the impact limiter should be properly determined for the impact limiter to absorb the impact energy and reduce the impact force. Therefore, the design parameters of the impact limiter were optimized to obtain a feasible optimal design. The design feasibility criteria were investigated, and several objectives were defined to obtain various design solutions. Furthermore, a probabilistic approach was introduced considering the uncertainties included in an engineering system. The uncertainty of material properties was assumed to be a random variable, and the probabilistic feasibility, based on the stochastic approach, was evaluated using reliability. Monte Carlo simulation was used to calculate the reliability to ensure a proper safety margin under the influence of uncertainties. The proposed methodology can provide a useful approach for the preliminary design of the impact limiter prior to the detailed design stage.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.3 s.153
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• pp.296-304
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• 2007

The objective of this paper is to investigate the dynamic strength characteristics of LNG carriers cargo containment system under impact loads experimentally. The material properties were experimentally obtained for individual components of MARK III insulation system. A series of impact tests was performed using a custom-built drop experiment facility as varying heights and weights of the drop object. Crack initiation and propagation were measured during the cyclic dry drop experiment. The quantitative relationship between impact load and crack initiation as well as the cycle number and crack propagation were reported.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.5-11
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• 2015

In a pressurized water reactor (PWR), control rod assembly (CRA) falls into the guide tubes of a fuel assembly due to gravity for scram. Various theoretical approaches and numerical analyses have been performed because its shape is simple and its design was completely developed several decades ago. A control rod assembly for a sodium-cooled faster reactor (SFR) which is geometrically more complicated is being actively developed in Korea nowadays. Drop time and impact velocity of a CRA are important parameters with respect to reactivity insertion time and the mechanical robustness of a CRA and a guide duct. In this paper, computational method considering simultaneously the equation of motion for rigid body and the Navier-Stokes equations for fluid is suggested and verified by comparison with theoretical analysis results. Through this valuable CFD analysis method, drop time and impact velocity of initially designed SFR CRA are evaluated before performing scram tests with it.

• Journal of International Academy of Physical Therapy Research
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• v.2 no.1
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• pp.222-228
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• 2011

With comparison of maximum vertical reaction force and lower limb on drop landing between normal and flat foot group, this study is to provide fundamental data of the prevention of injury and the treatment of exercise which are frequently occurred on flat foot group's drop landing. The surface electrodes were sticked on lateral gastrocnemius muscle, medial gastrocnemius muscle, tibialis anterior and the drop landing on a force plate of 40cm was performed with a normal group who had no musculoskeletal disease and a flat foot group of 9 people who had feet examinations. Vertical reaction force were significantly statistically different between two groups(p<.001). Muscle activity of lower limbs in all three parts were not statistically different but showed high tendency on average in the flat foot group. The flat foot group had difficulties in diversification of impact burden and high muscle activity. Therefore, it was suggested that muscular strengthening of knee joints and plantar flexions of foot joints which were highly affected in impact absorption will be required.