• Composites Research
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• v.34 no.1
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• pp.1-7
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• 2021

Fiber-reinforced thermoplastic composites are applied to transport industries to lightweight of body, and applications will be expanded gradually. In this study, the impregnation and mechanical properties of continuous glass fiber (GF) reinforced polycarbonate (PC) composites were evaluated with different molecular weights of PC. The continuous GF reinforced PC composite were prepared by using GF fabric and PC film via continuous compression molding method. The melting flow index and tensile strength of PC matrix were evaluated with different molecular weights. Mechanical properties (tensile, flexural, and compressive) and pore rate of GF/PC composite were evaluated with different molecular weights of PC. The fracture behavior was analyzed to fracture surface of GF/PC composite using FE-SEM images. As these results, it was condition of representing the best mechanical property that the GF/PC composite was prepared by using PC of 20,000 g/mol as matrix.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.149-153
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• 1999

During a hemisphere-type compression molding, the wrinkles are caused by complex stress condition. It is very important to clarify the degree of wrinkles in order to have good products. In this paper, the effects of numbers of needling and initial area on the degree of wrinkles are studied. the degree of wrinkle is expressed as nonhomogeneity.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.331-334
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• 2006

In this study, the ultra-fine fibers (UFs) having an alignment were prepared by electrospinning process, using different collectors made from various materials and collecting methods. A spinning solution was prepared by dissolving poly(amide-co-imide) (PAI) in NMP. The UFs were prepared by using various collectors and collecting methods, and the fibrous shapes were observed by SEM. As a result, a sort of materials of collectors and the collecting methods had not influenced on the average diameters of fibers but the forms of them. The just accumulated UFs on the collectors formed net structures, which had no alignment. On the contrary, the continuously collected UFs formed long fibers with alignment. It was found that the water collector played the roles of the fiber haul, temporary collector, moving path of fibers, and caused some friction between fibers and water, attributed to the formation of continuous UFs at a suitable collecting speed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.472-476
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• 2011

This paper presents the results of theoretical analysis and experimental test to verify the size effect on the fiber strength of filament wound pressure vessel. As a test method, a series of fully scaled hoop ring tests with filament wound carbon fiber-epoxy has been conducted. Test results showed remarkable size effect on fiber strength. And, as an analytical method, the WWLM(Weibull weakest link model) and SMFM(sequential multi-step failure model) were considered and compared to hoop ring test data. The analysis results showed significantly lower fiber strength value than that of test data. Through the modification of length size effect, modified SMFM is suggested. The fiber strengths from modified SMFM showed good agreement with test data.

• Composites Research
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• v.24 no.5
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• pp.1-8
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• 2011

This paper presents the results of theoretical analysis and experimental test to show the size effect on the fiber strength of filament would pressure vessel. First, a series of fully scaled hoop ring tests with filament would carbon-epoxy were conducted, which exhibited a remarkable size effect on the fiber strength. Next, the failure analyses using WWLM(Weibull Weakest Link Model) and the SMFM(Sequential Multi-step Failure Model) were performed and compared to the hoop ring test data, as well as to unidirectional specimens test data from the literature. It was found that the analysis results significantly underestimated the fiber strengths compared to the test data. In this study, a modified SMFM was proposed through the modification of the length size effect. The fiber strengths from modified SMFM analysis showed good agreement with the test data.

• KSBB Journal
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• v.5 no.1
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• pp.59-67
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• 1990

Enzymatic hydrolysis of insoluble cellulose was performed in a bubble column with tangential flow ulrafiltration membrane unit. The reactor was operated in a batch mode as well as semi-continuous and continuous with continuous removal of products through the tangential flow ultrafiltration membrane. The optimum superficial gas velocity was 1-3cm / sec so as to avoid bubble coalescence and enzyme denaturation. In continuous and selni-cotinuous process, the conversion was gradually increased but the total reduced sugar concentration was drcastically dereased with the dilution rate. It was concluded that the bubble column attaching tangential flow ultrafiltration membrane unit was effective on continuous hydrolysis of cellulose and recovery of enzyme.

• Fiber Technology and Industry
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• v.9 no.4 s.36
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• pp.391-398
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• 2005

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.177-182
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• 1999

사용한 보수.보강재, Rod, Fabric, Strand 형상을 콘크리트 구조물등에 보강재로 사용되어왔다. 이 재료는 해양환경하에서 내식성과 내구성을 갖는 철근및 철골대체용 복합소재와 초고층 경량 연속섬유보강 시멘트 복합재료는 탄소섬유, 아라미드섬유, 유리섬유등의 쉬트(sheet)형상을 신건재, 비자성, 비전도성, 전파차폐용 재료등에 사용할수있다. 그러나 FRP Rod를 내식성이 요구되는 철근 및 철골대체재로 사용할 경우에는 폴리머 매트릭스의 열화, 섬유와 폴리머간 계면 접착강도의 한계, 화재시 내화성, 보강재의 인발성등의 단점들을 갖고있다[1]. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.419-420
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• 2003

PET 섬유는 굴절률이 1.64로서 다른 섬유에 비해 높고 표면이 매끄러우며 몰흡광계수가 낮은 분산염료로 염색되기 때문에 섬유표면에서 가시광선의 반사율이 커서 염색된 후에도 색이 진하게 보이지 않는 결점이 있다. PET 섬유의 심색화법으로는 염료가 쉽게 침투할 수 있게 구조를 변화시키거나, 섬유를 개질하여 흡광성이 우수한 염기성 염료 등으로 염색을 하는 방법, 섬유표면에 요철구조를 만들고 저굴절율의 수지피막을 형성시켜 빛의 표면반사를 줄여주는 방법 등이 가능한 것으로 알려져 있다. (중략)

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.163-172
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• 2003

As concrete structures are getting larger, higher, longer, and specialized, it is more required to develop steel fiber concrete and apply to the real world. In this research, it is aimed to have fatigue strength examined, varying the steel fiber content by 0%, 0.75%, 1.00%, 1.25%, by experimental study of Two-spans Beam with Steel Fibrous with repeated loads. The ultimate load and the initial load of flexural cracking were measured by static test. In addition, the load versus strain relation, load versus strain relation, load versus deflection relation, crack pattern and fracture mode by increasing weight was observed. On the other hand, the crack propagation and the modes of fracture according to cycle number and the relation of cycle loading to deflection relation and strain relation was observed by fatigue test. As the result of fatigue test, Two-spans Beam without Steel Fibrous was failed at 60~70% of the static ultimate strength and it could be concluded that fatigue strength to two million cycle was around 67.2% by S-N curve. On the other hand, that with Steel Fibrous was failed at 65~85% of the static ultimate strength and it could be concluded fatigue strength to two million cycle around 71.7%.