• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.7-10
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• 2005

This paper is about manufacture of spalling resistance concrete and also investigates the spalling mechanism and spalling resistance method with diverse materials, mixture proportion and lateral confinement. The present work with the basic experiment achieved successful method for spatting resistance using both proper amounts of fiber contents and lateral confinement using metal lath. Moreover, the developed spatting resistance method was applied for full sized column construction in the Doosan We've Poseidon I field, located in Busan city. The author investigated the physical properties examining workability, placeability and pumpability. These studies are continuously processing to develop new technology expecting remarkable impact on the spatting resistance and fire resistance performance of high-raise building construction in the future.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.128-134
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• 2013

High bending collapse performance (maximum resistance force and mean resistance force) of body center pillar is an important design target for vehicle safety against side impact. In this study, effect of the upper section shape and the thickness of outer reinforcement on bending collapse performance was investigated for the center pillar of a large passenger car. First, through bending collapse analyses using simple models with uniform section, an optimized center pillar upper section was chosen. Next, bending collapse performance for various models of the actual center pillar with changing the thickness of outer reinforcement were analyzed. The finally designed model showed distinctive enhancement in bending collapse performance nearly without weight increase.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.7
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• pp.27-37
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• 2003

This study was performed to examine the flowing ability and filling ability of polypropylene fiber reinforced high performance concrete. The slump flow was decreased with increasing the polypropylene fiber content, rapidly. At the box-type filling ability, the difference of box height was increased with increasing the fiber content and the box-type passing ability was closed in fiber content 1 %. The final flowing distance of L-type was decreased with increasing the fiber content. Also, it was decreased above 0.75% of polypropylene fiber content, rapidly. The filling ability of L-type was badly showed above polypropylene fiber content 0.75%. Also, the compressive strength was decreased with increasing the fiber content, but the flexural strength was shown higher than that of the concrete without fiber. At the impact resistance, drop numbers for reaching in final fracture were increased with increasing the fiber content. Also, the drop numbers for reaching initial fracture of 1mm were increased with increasing the fiber content. At the acid resistance, the percent of original mass was decreased with increasing the fiber content.

• Structural Engineering and Mechanics
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• v.91 no.2
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• pp.177-195
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• 2024

This research plans to investigate the simultaneous impact of bamboo fibers (BF) and steel fibers (SF) on the mechanical and spalling characteristics of ultra-high-performance concrete (UHPC) exposed to high temperatures (HT). To this aim, 25 mixtures were made and assessed. BF was added at five contents of 0, 2.5, 5, 7.5 and 10 kg/m³. Additionally, SF was used at five weight contents: 0%, 1%, 2%, 3% and 4%. Specimens were exposed to temperatures ranging between 25℃ and 800℃. Thus, com-pressive, tensile, and flexural strengths, elastic moduli, mass loss, and permeability were measured. Experiments revealed that the simultaneous use of low BF and SF contents could totally prevent spalling of UHPC, but the use of either SF or BF alone could not prevent spalling at high levels of fibers. Besides, the synergetic positive impact of BF and SF on the spalling resistance of UHPC was by reason of the rise of BF' permeability and the bridging role of SF at HT. Moreover, it was concluded that the use of SF could moderate the adverse influence of BF on the compressive resistance of UHPC.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.535-546
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• 2010

Recently, the probability of collision accident between vehicles or vessels and infrastructures are increasing at alarming rate. Particularly, collision impact load can be detrimental to sub-structures such as piers and columns. The damaged pier from an impact load of a vehicle or a vessel can lead to member damages, which make the member more vulnerable to impact load due to other accidents which. In extreme case, may cause structural collapse. Therefore, in this study, the vehicle impact load on concrete compression member was considered to assess the quantitative design resistance capacity to improve, the existing design method and to setup the new damage assessment method. The case study was carried out using the LS-DYNA, an explicit finite element analysis program. The parameters for the case study were cross-section variation of pier, impact load angle, permanent axial load and axial load ratio, concrete strength, longitudinal and lateral rebar ratios, and slenderness ratio. Using the analysis results, the performance based resistance capacity evaluation method for impact load using satisfaction curve was developed using Bayesian probabilistic method, which can be applied to reinforced concrete column design for impact loads.

• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.731-739
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• 2014

This paper describes the evaluation of the impact performance of steel fiber-reinforced concrete based on high-velocity impact experiments using hard spherical balls. In this experimental study, panel specimens with panel thickness to ball diameter (h/d) ratios of 3.5 or less were tested with variables of steel fiber volume fraction, panel thickness, impact velocity, and aggregate size. Test results were compared with each other to evaluate the impact resistance. The results showed that the percentage of weight and surface loss decreased as the steel volume fraction increased. However, the penetration depth increased with up to steel fiber volume fraction of 1.5%. Particularly the results of specimens with 20 mm aggregates showed poorer performance than those with 8 mm aggregates. The results also confirmed that the impact performance prediction formulas are conservative with (h/d) ratios of 3.5 or less. Despite the conservative predictions, the modified NDRC formula and ACE formula predict the impact performance more consistently than the Hughes formula.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.273-278
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• 2003

Recently, high-performance hybrid composite materials have been used for various industrial fields because of their superior high strength, high stiffness and lower weight. In this study, manufactured hybrid composite materials are composed of two parts. One is hard-anodized Al5083-O alloy as a face material and the other is high strength aramid fiber ($Twaron^{(R)}$ CT709) laminates as a back-up material. Resistance to penetration is determined by protection ballistic limit($V_{50}$, a static velocity with 50% probability for complete penetration) test method. $V_{50}$ tests with $0^{\circ}$obliquity at room temperature were conducted with 5.56mm ball projectiles that were able to achieve near or complete penetration during high velocity impact tests.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.83-87
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• 2023

In the field of electronics and semiconductor technology, innovative semiconductor material research to replace Si is actively ongoing. However, while research on alternative materials is underway, there is a significant lack of studies regarding the relationship between 2D materials used as channels in transistors, especially parasitic resistance, and RF (radio frequency) applications. This study systematically analyzes the impact on electrical performance with a focus on various transistor structures to address this gap. The research results confirm that access resistance and contact resistance act as major factors contributing to the degradation of semiconductor device performance, particularly when highly scaled down. As the demand for high-frequency RF components continues to grow, establishing guidelines for optimizing component structures and elements to achieve desired RF performance is crucial. This study aims to contribute to this goal by providing structural guidelines that can aid in the design and development of next-generation RF transistors using 2D materials as channels.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.610-613
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• 2006

This paper is the fundamental study for manufacture of spalling resistance concrete and also analyses the mechanism and spalling resistance method with materials, mixture proportion and lateral confinement. The present work with the basic experiment achieved successful method for spalling resistance using both proper amounts of fiber contents and lateral confinement using metal lath. Moreover, the developed spalling resistance method was applied for full sized column construction in the Doosan We've Poseidon I field, located in Busan city. Authors investigated the physical properties examining workability, placeability and pumpability. These studies are continuously processing to develop new technology expecting remarkable impact on the spalling resistance and fire resistance performance of high-raise building construction in the future.

• Journal of Auto-vehicle Safety Association
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• v.6 no.2
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• pp.55-60
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• 2014

To verify the performance of roadside safety facilities, strength and occupant protection test are performed by evaluation criteria. Strength test use a truck and occupant protection test use a sedan. Strength perfomance is analyzed pass rate by post lateral resistance of the safety barrier. Occupant protection performance is analyzed from THIV(Theoretical Head Impact Velocity) and PHD(Post-impact Head Deceleration) by crash cushion test.