• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.277-280
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• 2014

Recently, military vehicles that are being driven are equipped with a lot of electronic devices. The military vehicles are easily exposed to impact. Thus, they have to be designed robustly to ensure that the stability of the vehicle and the electronic equipment. In order to design the vehicles efficiently, the dynamic characteristics of a military vehicle have to be identified exactly. The main frame has a significant role to the dynamic characteristics of the vehicle. Thus, this research was progressed mainly with the frame. By carrying out road tests, the characteristics could be identified. Also, based on the characteristics, we constructed FE model of the frame and performed the analysis of the dynamic characteristics of the vehicle.

• Journal of Auto-vehicle Safety Association
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• v.7 no.1
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• pp.13-19
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• 2015

Recently, Child safety has become one of the issue with Q10 dummy representing large child. The objective of this paper was to evaluate performance of three child restraints system (backless booster, high-back booster and without booster) by changing D-ring location in the rear seat. Sled tests were carried out with a Q 10 in 64km/h frontal impact. Before the dynamic sled tests, we assessed dummy positioning with difference in CRS types and height adjustment positions. Dynamic sled test results indicated that there is different performance of CRS types and belt routing. These test results will use as base line data for development CRS safety performance for Q 10.

• Structural Engineering and Mechanics
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• v.41 no.1
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• pp.83-94
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• 2012

Assessment of a monumental concrete arch bridge with a total length of 210 meters having three major spans of 30 meters and a height of 65 meters, which is located in an earthquake-prone region in southern part of the country is presented in this study. Three-dimensional finite element model of the bridge was generated using a commercially available general finite element analysis software and based on the outcomes of a series of in-depth acceleration measurements that were conducted on-site, the model was refined. By using the structural parameters obtained from the dynamic and the static tests, calibrated model of the bridge structure was obtained and this model was used for necessary calculations regarding structural assessment and evaluation.

• Geomechanics and Engineering
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• v.5 no.4
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• pp.331-342
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• 2013

The major factors that control the performance of reinforced soil structures is the interaction between the soil and the reinforcement. Thus it is necessary to obtain the accurate bond parameters to be used in the design of these structures. To evaluate the behavior of flyash + clay soil reinforced with a woven geotextile, 36 Unconsolidated-Undrained (UU) and 12 reinforced Consolidated-Undrainrained (CU) triaxial compression tests were conducted. The moisture content of soil during remolding, confining pressures and arrangement of geotextile layers were all varied so that the behavior of the sample could be examined. The stress strain patterns, drainage, modulus of deformation, effect of confinement pressures, effects of moisture content have been evaluated. The impact of moisture content in flyash + clay backfills on critical shear parameters was also studied to recommend placement moisture for compaction to MDD. The results indicate that geotextile reinforced flyash + clay backfill might be a viable alternative in reinforced soil structures if good-quality granular backfill material is not readily available.

• Transactions of the Society of Information Storage Systems
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• v.11 no.2
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• pp.26-30
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• 2015

Recently, military vehicles are driven with a lot of electronic devices such as radar, antenna, and information storage devices. However, the military vehicles can be exposed to impact easily. Therefore, they have to be designed robustly in order to ensure the stability of the vehicle and the electronic devices. To achieve that, the dynamic behaviors of the military vehicle should be exactly identified. Therefore, in this research, dynamic behaviors of the vehicles were identified by carrying out road tests and we constructed finite element model to analyze the dynamic characteristics of the vehicle.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.2
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• pp.7-12
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• 2012

A landing gear absorbs the impact energy during the touchdown and it generally consists of an oleo-pneumatic shock absorber and structural components. It should be designed not only to satisfy the static and fatigue strength requirements but to have the sufficient shock absorbing efficiency. The design loads and shock absorbing performance are to be validated by tests, which is required by MIL Spec and FAR, etc. This paper presents the development procedures from the design requirements to the qualification tests and technical points to be considered, with examples of the helicopter landing gear development.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2295-2303
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• 2021

To investigate wall-thinning impact on axial load resistance of Zircaloy-4 cladding rods after a LOCA transient, axial tensile samples have been machined on as-received tubes with reduced thicknesses between 370 and 580 ㎛. After high temperature oxidation under steam at 1200 ℃ with measured ECR ranging from 10 to 18% and water quenching, machined samples were axially loaded until fracture. These tests were modeled using a fracture mechanics approach developed in a previous study. Fracture stresses are rather well predicted. However, the slightly lower fracture stress observed for wall-thinned samples is not anticipated by this modeling approach. The results from this study confirm that characterizing the axial load resistance using semi-integral tests including the creep and burst phases was the best option to obtain accurate axial strengths describing accurately the influence of wall-thinning at burst region.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1602-1611
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• 2021

A varying degree of eccentricity always exists in the initial configuration of a nuclear fuel rod. Its impact on traditional LWR fuel is limited as the radial gap closes relatively early during irradiation. However, the effect of misalignment is expected to be more relevant in rods with highly conductive fuels, large initial gaps and low conductivity filling gases. In this paper, we study similar characteristics in the experimental setup of two fuel disc irradiation campaigns carried out in the OECD Halden Boiling Water Reactor. Using the multi-dimensional fuel performance code OFFBEAT, we combine 2-D axisymmetric and 3-D simulations to investigate the effect of eccentricity on the fuel temperature distribution. At the same time, we illustrate how the advent of modern tools with multi-dimensional capabilities might further improve the design and interpretation of in-pile separate-effect tests and we outline the potential of such an analysis for upcoming experiments.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.25-33
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• 2021

This paper presents the development process for airbag safety devices fitted in motorcyclists' garments. Motorcycle riders often sustain multiple injuries in crashes since rider post-impact kinematics depend on several variables. This study proposes a newly inflatable safety system connected to the motorcycle by a cable. An airbag device with a mechanical triggering system is deployed when the cable detaches from its mounting clip. Airbag filling tests are performed to determine the mixing ratio of compressed gases with the severance of temperature. To estimate the airbag effectiveness to reduce riders' injuries, numerical analysis is performed using the finite element method. A comparative analysis (i.e., with and without the chosen device) was conducted to evaluate its protective efficacy. Prototype garments based on the proposed design have been created and have undergone sled tests. The proposed safety device could also be beneficial in accidents during other sports activities.

• Journal of Navigation and Port Research
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• v.46 no.2
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• pp.82-91
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• 2022

When a ship moves in the proximity of the lateral bank, bank suction forces are generated due to bank effects. Thus, hydrodynamic forces can significantly impact the ship's maneuverability and navigation safety. In this study, model tests were performed to investigate the hydrodynamic forces exerted on a ship, especially suction forces caused by bank effects, using captive model and bank effect tests. A low-speed condition was selected in this study, because of the perilous situation as the ship moves close to the bank. The accuracy of the hydrodynamic forces exerted on the hull was verified, by comparing the results of the static drift test with the results obtained from other institutes at design speed. The straight simulation caused by bank effects was then implemented using estimated hydrodynamic coefficients.