• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.381-382
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• 2010

The fiber dispersion performance in fiber-reinforced cementitious composites is a crucial factor with respect to achieving desired mechanical performance. Thus, fiber dispersion of ECC incorporated by recycled mineral wastes was evaluated to more accurately predict uniaxial tension behavior.

• Composites Research
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• v.23 no.1
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• pp.51-53
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• 2010

자기장하에서 액체 성질인 유동성과 고체 성질인 자성을 갖는 강자성/자기흐름 유체의 제조방법, 강자성/자기흐름 유체의 조성 및 미세구조와 유체 매트릭스의 구조에 따른 자기특성과 강자성/자기흐름 유체의 물리적, 기계적 성질을 조사하고 최근 연구개발되고 있는 전기흐름유체(electrorheological fluid)의 특성과 비교하였으며, 또한 이를 바탕으로 방탄복에 대한 적용성을 검토하였다.

• Composites Research
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• v.30 no.5
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• pp.316-322
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• 2017

Carbon fiber is a material with excellent mechanical, electrical and thermal properties, which is widely used as a composite material made of a polymer matrix. However, this composite material has a weak point of interlaminar delamination due to weak interfacial bond with polymer matrix compared with high strength and elasticity of carbon fiber. In order to solve this problem, it is essential to use reinforcements. Due to excellent mechanical properties, graphene have been expected to have large improvement in physical properties as a reinforcing material. However, the aggregation of graphene and the weak interfacial bonding have resulted in failure to properly implement reinforcement effect. In order to solve this problems, dispersibility will be improved. In this study, functionalization of graphene nanoplatelet was proceeded with melamine and mixed with epoxy polymer matrix. The carbon fiber reinforced polymer composites were fabricated using the prepared graphene nanoplatelet/epoxy and flexural properties and interlaminar shear strength were measured. As a result, it was confirmed that the dispersibility of graphene nanoplatelet was improved and the mechanical properties of the composite material were increased.

• Polymer(Korea)
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• v.25 no.3
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• pp.334-342
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• 2001

Gentamicin sulfate (GS)-loaded poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) devices were prepared for controlled-release of antibiotics. In this study, the effects of thickness, hydroxyvalerate (HV) content, initial drug-loading ratio, and additive content on the release profile have been investigated. The morphology of devices was examined with scanning electron microscope (SEM) before and after in vitro release; their highly porous surface and cross-sectional were observed. It could be suggested that device would be affected by the packing of the HV and additive content, which would depend on their structure. A high performance liquid chromatography (HPLC) was used to detect and quantify the release of GS from the device. The drug release from all the devices showed biphasic release patterns, and some matrices released the incorporated antibiotic throughout 30 days with a near zero-order release rate. The release patterns were shown to be changed by altering the thickness, copolymer ratio, and additive content.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.865-872
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• 2004

Web applications have different structural characteristics from conventional applications with the structural language or object-oriented language or 4GL. A web application typically consists of server-side script elements which run on web sewers, client-side script elements which run on the client web-browser, HTML elements that contains context. Therefore web applications developer concurrently uses 3 or more development language. Cyclomatic Complexity for Web Application(CCWA) metrics reflected composite complexity of each element. In this paper, we applied cyclomatic complexity for web application metrics with Complexity level indicator to web application. We applied it to 10 web applications that were developed in practical business. High complexity web applications classify into four type(MENU, FORM, CTRL, GEN). This paper has contributed to practical use of engineering approach for web application.

• Fire Science and Engineering
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• v.33 no.5
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• pp.19-27
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• 2019

Fire extinguishing composite materials based on low-viscosity epoxy resin (EP) and containing 50 wt% of encapsulated fire extinguishing agent (EFA) have been studied. The positive effect of the EP on the kinetics and temperature of the EFA decapsulation was established. The EP increases the decapsulation temperature of the EFA from 130 ℃ to 155 ℃ and changes the kinetics of the decapsulation. The epoxy matrix increases the thermal stability of the EFA more than 3.9 times compared to that of the pure EFA. The protective effect of the EP on the storage stability of the EFA was validated. The mass loss of EP-containing EFA at 60 ℃ and 80% humidity over 96 h is 0.4%. The mass loss of pure EFA under the same conditions is 15%. A similar effect was observed under ultraviolet radiation: the EP-containing EFA loses 0.8% at pure EFA mass of 6%. The testing of alternative polymer matrixes has been considered.

• Polymer(Korea)
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• v.24 no.2
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• pp.276-280
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• 2000

A conductive poly(acrylonitrile)/polypyrrole composite fabric was prepared. A conductive composite was prepared by the impregnation of PAN fabric into a mixed solution of pyrrole and oxidant in order to induce the in-situ polymerization of a conducting polymer into the matrix fabric. In the composite formation, the reaction condition was optimized to achieve the best properties, and the effect of the externally-added arylsulfonate dopants on the physical properties was examined. As a result, the best properties of electrical conductivity, thermal stability, and fastness to washing, was observed in the composite containing an antraquinonesulfonate (AQSA) dopant.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.176.2-176.2
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• 2011

전 세계는 화석연료의 과사용으로 에너지 고갈과 환경오염의 문제에 직면하고 있으며, 자연과 공존하며 지속성장할 수 있는 신재생에너지의 이용확대에 대한 개발이 부각되고 있다. 이에 따라 지속적인 발전과 함께 에너지보존 및 효율적인 환경보존을 위한 대체 가능한 새로운 에너지의 개발에 관심이 모아지고 있다. 최근 부각되고 있는 바이오에너지(바이오에탄올, 바이오디젤, 바이오가스 등)를 생산하는 여러 가지 새로운 바이오매스 중 해조류는 이산화탄소 흡수 능력이 매우 뛰어나고, 에너지 저장성이 우수하다는 장점이 있다. 본 연구에서는 새로운 바이오매스원인 해조류의 부산물의 표면 특성 및 바이오복합재료의 보강재로써의 이용가능성에 대해 분석하였다. 바이오복합재료에서 소수성인 고분자와의 상호보완적 계면 결합은 보강재의 중요한 특성 중 하나이다. 해조류 부산물의 표면을 화학적 처리함으로써 폴리머 매트릭스와 해조류 부산물 사이의 계면결합이 향상됨을 기대할 수 있으며 이에 따라 해조류 부산물을 보강재로 사용한 바이오복합재료의 기계적 강도 또한 향상됨을 기대할 수 있다. 본 연구에서는 원자힘현미경(Atomic force microscope; AFM)을 사용하여 해조류 부산물의 화학적 처리에 따른 표면특성을 관찰하였으며, 친환경적인 바이오매스인 해조류 부산물을 바이오복합재료의 보강재로써의 이용가능성에 대해 연구함으로써, 지구온난화의 주원인인 온실가스 발생을 줄이고, 자원고갈이라는 에너지 위기를 극복할 수 있는 친환경적인 대안을 제시 할 수 있다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.260-267
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• 2021

The purpose of this study was to experimentally investigate the effects of curing methods on the compressive strength and tensile behavior of alkali-activated slag-based fiber-reinforced composite with a water-to-binder ratio of 15%. Three kinds of mixtures according to the curing conditions were prepared and compressive strength and tension tests were performed. Test results showed that the compressive strength and the first cracking strength of composites decreased when high temperature curing and air curing were adopted, while tensile strain capacity of composites increased. It was also observed that crack spacing and crack width of composites decreased by applying high temperature and air curing.

• Polymer(Korea)
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• v.30 no.2
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• pp.129-134
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• 2006

Nanocomposites of polyurethane were prepared from inorganic nano particles, $Na^+-montmorillonite$ (MMT), silica, $CaCO_3$, and surface modified MMT and their properties were investigated. It was shown that the molecular weight and polydispenity of nanocomposites of polyurethane were 20000 to 28000 and 1.0 to 2.0, respectively. d-Spacing for nanocomposites of MMT were increased than that of pure MMT. Initial degradation temperature of nanocomposites were 250 to $280^{\circ}C$. And also, the range of weight loss for nanocomposites were decreased and the end of thermal degradation was observed at higher temperatures about $50^{\circ}C$. The elongation at break for $CaCO_3$ filled nanocomposites were the highest among the nanocomposites used in this study. studied. It was found that the tensile strength increased with increasing the filler contents while the silica nanocomposite exhibited the lowest increase and the $CaCO_3$ nanocomposite the highest.