• Composites Research
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• v.18 no.6
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• pp.40-47
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• 2005

In this study, we tried to invent ceramic armor material with brilliant ballistic properties by the silica of the high compression-expansion ratio and based on alumina that has the most economical and higher ballistic efficiency. After we choose three compositions, proper sintering temperature for each composition was decided. After physical/mechanical measurement, we measured ballistic properties about KE(Kinetic Energy, L/D=10.7, tungsten heavy alloy) and HEAT(High Explosive Anti-Tank, K215) projectiles. As a result, $46\%\;Al_2O_3\;-\;51\%\;SiO_2$ of three compositions had the highest ballistic efficiency md better properties than alumina.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.130-133
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• 1999

본 연구에서는 AC8A 알루미늄 합금과 HTZ 단섬유 및 알루미나(A12O3) 입자(particle)를 이용하여 HTZ 및 혼합 금속복합재료를 개발하고 정하중 시험을 통하여 개발된 재료의 상온 및 고온 기계적 물성을 규명하였으며, 개발된 금속복합재료가 고온에 노출되어 있을 경우 발생하는 aging에 의한 재료의 물성 변화를 분석하였다.

• Composites Research
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• v.17 no.6
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• pp.1-7
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• 2004

The studies of particulate reinforced composites have been conducted for many years. The nanocomposites to be studied vigorously in recent years are one of them. We fabricated and studied multi-walled carbon nanotube(MWNT)/epoxy composites which may be useful as matrix for continuous fiber-reinforced composites. We investigated tensile properties of MWNT/epoxy composites as a function of MWNT concentration, which were prepared by the fabrication method established in this study. Tensile stiffness and strength increased 19% at 0.5 wt% and 12% at 0.2 wt%, respectively. We observed the reaggregation phenomenon of MWNTS during curing, which should be controlled to obtain higher tensile properties.

• Composites Research
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• v.18 no.3
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• pp.1-6
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• 2005

Carbon nanofiber exhibits superior and of ien unique characteristics of mechanical, electrical, chemical and thermal properties. Despite of the excellent properties of carbon nanofiber, the properties of carbon nanofiber filled polymer composites were not increased largely. The reason is that it is still difficult to ensure the uniform dispersion of carbon nanofiber in a polymer matrix. In this study, for improvement of the mechanical properties of composites, carbon nanofiber reinforced hybrid composites was investigated. For the dispersion of carbon nanofiber. solution blending method using ultrasonic was used. Dispersion of carbon nanoifiber was observed by scanning electron microscope (SEH). Mechanical properties were measured by universal testing machine(UTM).

• The Journal of the Acoustical Society of Korea
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• v.42 no.5
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• pp.377-387
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• 2023

This paper presents accuracy of a method that directly estimates equivalent properties of a 1-3 piezocomposite for modeling it into the single phase homogeneous piezomaterial. This direct estimation method finds individual components of a material property matrix based on the piezoelectric constitutive equations, which represent mechanical and electrical behaviors and their couplings. Equivalent properties on a single 1-3 piezocomposite hydrophone are derived, and their accuracy depending on pairing of the constitutive equations is investigated by comparing them with finite element analysis for the whole domain. The accuracy is related to elastic characteristics of a matrix polymer, and the error is analyzed so that some guidelines for correct estimation are suggested. Fidelity of estimated properties and equivalent modeling is shown in a stave scale including hydrophones and surrounding acoustic structures as well, and reduced computational cost is verified.

• Composites Research
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• v.18 no.6
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• pp.34-39
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• 2005

In this study, we analyzed the relation between physical/mechanical properties and ballistic properties for several engineering ceramics that were expected to use as armor material. After physical/mechanical measurement, we measured ballistic properties about KE(Kinetic Energy, L/D=10.7, tungsten heavy alloy) and HEAT(High Explosive Anti-Tank, K215) projectiles. Increasing Young's modulus/density, hardness/density and flexural strength/density ratios, ballistic properties were generally increased. Especially it appeared that the ballistic property about KE projectile was lineally increased, as HEL/density ratio increased.

• Composites Research
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• v.29 no.1
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• pp.33-39
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• 2016

In this study, geometric modeling and finite element analysis of 3-dimensional plain weave composite unit cell consisting of 3 interlaced fiber tows and resin pocket were performed to predict effective properties. First, tow properties were obtained from micro-mechanics finite element unit cell analysis, which were then used in the meso-mechanics analysis. The effective properties were obtained from a series of unit cell analyses simulating uniaxial tensile and shear tests. Analysis results were compared to the analysis and experimental results in the literature. Various crimp angles were considered and the effect on the effective properties was investigated. Initial failure strengths and failure sequence were also examined.

• Composites Research
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• v.26 no.5
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• pp.303-308
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• 2013

Carbon fiber (CF) reinforced polypropylene (PP) compositeis was increased to amount consumed. In this study, recycle of composites by recycle times. CF was containing 20%. Mechanical and interfacial propertis of CF/PP was evaluation for number of recycle time. Mechanical assessment of CF/PP was tension, bending, fatigue tension test and izod test method. Interfacial assessment of CF/PP was wettability test and FE-SEM of fracture surface method. Fiber and matrix was changed to recycle time. The more recycle of CF/PP, the more interfacial bonding was decreased. Because fiber and matrix was damaged to thermal damage. And then reinforced CF was shorter than original shape.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.859-869
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• 2009

The sharp indenters such as Berkovich and conical indenters have a geometrical self-similarity in theory, but different materials have the same load-depth curve in case of single indentation. In this study, we analyze the load-depth curves of conical indenter with angles of indenter via finite element method. From FE analyses of dual-conical indentation test, we investigate the relationships between indentation parameters and load-deflection curves. With numerical regressions of obtained data, we finally propose indentation formulae for material properties evaluation. The proposed approach provides stress-strain curve and the values of elastic modulus, yield strength and strain-hardening exponent with an average error of less than 2%. It is also discussed that the method is valid for any elastically deforming indenters made of tungsten carbide and diamond for instance. The proposed indentation approach provides a substantial enhancement in accuracy compared with the prior methods.

• The Journal of the Korea Contents Association
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• v.17 no.1
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• pp.157-165
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• 2017

Even though the importance of emotional aspects in design has been discussed and researched actively, researches mainly focusing on the emotional aspects expressed through architectural materials have been rare. Thus, Previous researches were investigated to draw typical categories to express emotional characteristics through architectural materiality. Case study shows Zumthor's practical methodologies in these state: tectonic expression with creative tectonic methods and local residents' voluntary-participation in construction; enhancement of intimate emotional ties with the local heritage through the usage of local materials and traditional construction techniques; coexistence of past and present materials, and showing the change of materiality via weathering; activation of synesthesia by touching multiple senses; sustainability by using environment friendly materials and construction methods. The results can be hopefully helpful to future researches related to emotional aspects on spatial design.