• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5C
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• pp.211-220
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• 2012

Coarse granular materials such as gravel, rubble is used as major fill materials in earth structures of railway, road and dam. Therefore, it is essential to accurately evaluate properties of these materials for reasonable design and construction. In the precedent study, we built large triaxial testing system and verified system compliance with a focus on the dynamic properties. And we could secured the reliability of the system. In this study, the cyclic triaxial tests were performed in various experimental conditions on coarse granular material. Two series of parallel graded samples are prepared by mixing crushed rock. The influence of grain size, loading pattern, loading frequency, and fine contents were analyzed and discussed.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.1-9
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• 2008

Fiber Reinforced Polymer (FRP) composites are used extensively in aerospace, marine, automotive, infrastructure, chemical processing and sporting good applications. A concern with using FRP composites in some engineering structures is their high flammability and poor fire resistance In this research, material properties of FRP composites at increasingly high temperatures was measured and verified. The obtained mechanical properties of FRP composites were performed according to ASTM D3039/D3039M and tested to a wide range of heat conditions with temperatures from Room-temp. to 300 for times up to 30 min. It is found that the mechanical properties of FRP composites dropped with increasing heat or temperature. The reduction to the properties was due mainly to thermal degradation and combustion of the polymer matrix.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.53-53
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• 2004

최근 자동차/항공기 등의 판재나 구조물을 첨단기능성 재료로 제작하여 연료소비량을 감소시키는 동시에 승객의 안정성을 현저히 향상시키는 초경량/고강도/고강성/고내충격성 재료에 대한 연구가 활발히 수행되고 있다. 국내에서는 두개의 금속 박판사이에 3차원 금속 구조체를 대면적에 분포시킨 후, 판재와 구조체를 접합하여 재료의 무게를 현저히 감소시키는 반면 강도/강성/내충격성을 향상시키는 ISB(Internally Structured Bonded)판재 개발에 대한 연구가 시작되고 있다.(중략)

• Composites Research
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• v.23 no.3
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• pp.37-42
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• 2010

The fiber material properties, elastic constant and strength, are the most important factors among the various material properties for the design of composite pressure vessel, because of it's dominant influence on the performance of composite pressure vessel. That is, the deformation and burst pressure of pressure vessel highly affected by the fiber material properties. Therefore, the establishment of test method for exact fiber material properties is a priority item to design a composite pressure vessel. However, the fiber material properties in filament wound pressure vessel is very sensitive on various processing variables (equipment, operator and environmental condition etc..) and size effect, so that it isn't possible to measure exact fiber material properties from existing test methods. The hydro-burst test with full scale pressure vessel is a best method to obtain fiber material properties, but it requires a enormous cost. Thus, this paper suggests a newly developed test method, hoop ring test, that is capable of pressure testing with ring specimens extracted from real composite pressure vessel. The fiber material properties from hoop ring test method showed good agreement with the results of hydro-burst test with full scale composite pressure vessels.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.88-88
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• 2004

내압을 받는 압력관의 파괴는 원주방향의 응력이 주된 요인이므로, 압력관의 안전성을 평가를 위해서는 원주방향의 인장특성을 아는 것이 필요하다. 소형 압력관의 인장특성을 평가할 때, 정확한 원주방향의 인장특성을 알기 위해서는 관으로 가공된 후의 재료로 시험해야 하지만, 부피의 제약으로 인하여 원주방향으로의 표준 인장시험편을 제작하지 못하므로 가공하기 전의 재료의 물성치를 사용하고 있다. 이를 개선하고자 원주방향의 인장특성을 평가하기 위한 방법의 하나로 링 시험법(ring test)이 있다.(중략)

• 기계와재료
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• v.17 no.4 s.66
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• pp.20-28
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• 2005

• Elastomers and Composites
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• v.42 no.1
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• pp.32-46
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• 2007

Mechanical properties of rubber material are very important in design procedure to assure the safety and reliability of the rubber components. In this paper, the material test and accelerated heat aging test were carried out. In order to investigate the effects of heat-aging on the material properties, hardness, elongation, stress-strain curves and dynamic characteristics were obtained from various test conditions. Also, rubber material coefficients were determined by both the uniaxical and equi-biaxial tensile tests.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.409-415
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• 2012

To recycle the steel slag as manufactured composite materials of polymer concretes, we used the atomizing method to make round aggregates from steel slag, which is treated as industrial wastes. A round rapid-cooled steel slag was used to replace fine aggregate (river sand) or coarse aggregate (crushed aggregate), depending on the grain size. To examine general physical properties of polymer concrete composites manufactured from rapid-cooled steel slag, the polymer concrete specimen with various proportions depending on the addition ratio of polymer binder and replacement ratio of rapid-cooled steel slag were manufactured. In the result of the tests, the mechanical strength of the specimen made by replacing the optimum amount of rapid-cooled steel slag increased notably (maximum compressive strength 117.1 MPa), and the use of polymer binder, which had the most impact on the production cost of polymer concrete composites, could be remarkably reduced. However, the mechanical strength of the specimen was markedly reduced in hot water resistance test of polymer concrete composite.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.153-162
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• 2002

This paper predicted the engineering constants of spatially reinforced carbon/ carbon composites and analyzed the mechanical behaviour of the kick motor nozzle. Those equivalent engineering constants are used to analyze the mechanical behaviour of the kick motor nozzle. Because the distribution of equivalent engineering constants is varying as change its structure, we made a program to predict engineering constants of spatially reinforced composites. The kick motor nozzle consists of graphite or spatially reinforced carbon/ carbon composites for the nozzle throat, carbon/ phenol for the nozzle entrance and the expansion part, and steel for the outer surface of the expansion part. The 4-D carbon/ carbon composite shows the smallest deformed shape of the nozzle throat, which has a favorable effect on the rocket thrust, and the most uniform deformation of all nozzle throat materials. In addition to analysis, ground firing tests of 4D C/ C nozzle throat and graphite nozzle throat were performed.

• Journal of Adhesion and Interface
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• v.4 no.1
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• pp.18-27
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• 2003

Interfacial properties and microfailure degradation mechanisms of the oxygen-plasma treated biodegradable poly(p-dioxanone) (PPDO) fiber/poly(L-lactide) (PLLA)composites were investigated for the orthopedic applications as implant materials using micromechanical technique and surface wettability measurement. PPDO fiber reinforced PLLA composite can provide good mechanical performance for long hydrolysis time. The degree of degradation for PPDO fiber and PLLA matrix was measured by thermal analysis and optical observation. IFSS and work of adhesion, $W_a$ between PPDO fiber and PLLA matrix showed the maximum at the plasma treatment time, at 60 seconds. Work of adhesion was lineally proportional to the IFSS. PPDO fiber showed ductile microfailure modes at We initial state, whereas brittle microfailure modes appeared with elapsing hydrolysis time. Interfacial properties and microfailure degradation mechanisms can be important factors to control bioabsorbable composites performance because IFSS changes with hydrolytic degradation.