• Polymer Science and Technology
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• v.21 no.2
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• pp.167-174
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• 2010

• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.144-147
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• 1998

다양한 변형 양식에 대한 고분자 물질의 응답특성을 예측하기 위해서는 완화 스펙트럼 H(λ) 또는 선형 완화 탄성율 G(t)를 결정하여야 한다. 완화 스펙트럼은 연속 완화 스펙트럼과 불연속 완화 스펙트럼(혹은 이산 완화 스펙트럼)으로 구분되며, 완화 스펙트럼과 완화 탄성율을 동적 점탄성으로부터 계산할 수 있는 여러 가지 방법들이 많은 연구자들에 의해 수행되어 왔다.(중략)

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.426-429
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• 1998

의복의 여러 가지 기능 중 하나는 인간을 열이나 추운 환경으로부터 보호하는 것이다. 이러한 의복 중 방염직물(flame-resistant fabrics)은 산업적으로 열과 접촉하거나 위험한 환경에서 작업하는 작업자들을 열로부터 보호하는 중요한 역할을 하고 있다. 내열성 방염직물로 만들어진 작업복이 요구되어 지는 작업환경은 제철소에서와 같이 연속적으로 위험성이 있는 곳과 비행기 사고나 건물화재와 같은 잠재 위험성이 있는 곳 등이다[1]. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.126-129
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• 2003

PEI(polyetherimide)는 고강도, 고탄성율를 가지며 20$0^{\circ}C$에서 연속사용이 가능한 고내열성, 내화학성을 가진 고성능 고분자이다. 우수한 물성과 더불어 성형성도 뛰어나 다양한 제품설계를 할 수 있으며, 특히 연소시 낮은 연기배출율(smoke emission)을 지니며, 고유의 우수한 난연성을 가지고 있다. 또한 광범위한 온도와 주파수대에서 높은 유전율과 전기 저항 특성을 유지할 수 있다. (중략)

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.983-992
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• 2005

The shear failure modes of fiber reinforced polymer(FRP) strengthened concrete beams are quite different to those of the beams strengthened with steel stirrups. When the beams are strengthened with larger amount of FRP composites, the beams normally fail in shear due to concrete crushing before the FRP reaches its rupture strain. In order to predict the shear strength of such beams, the actual rupture strain must be known. The equations previously reported in the technical literature adopt an effective reduction factor for the rupture strain. These equations may not be applicable to FRP strengthened RC beams that are beyond the experimental application limits, because most of these equations are empirical in nature. This paper presents the results of an analytical study on the performance of reinforced concrete beams externally wrapped with FRP composites and internally reinforced with conventional steel stirrups.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.88-95
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• 1996

유리섬유가 강화된 열가소성 복합재료 판재의 성형성에 대한 이해를 돕기 위해 이론적 고찰과 실험적 고찰이 행해졌다. 성형시험에서 사용된 형상은 임의의 방향으로 위치한 유리섬유를 중량비로 30% 함유한 폴리프로필렌 재료가 사용되었고, 시험된 형상은 판재의 굽힘성이나 인장성을 측정하는데 널리 사용되는 스위프트컵(Swift flat-bottomed cup)모양이다. 성형시험과 재료시험은 플리프로필렌 Matrix의 유리성 천이온도(Glass transition temperature)와 용융온도 사이에서 행해졌다. 본 연구의 이론과 고찰을 위해서 재료의 평면 방향으로는 동질성을 그리고 그 직각 방향으로는 이질성을 가진 연속체 물질로 가정하여 유도하였다. 이러한 이론적 결과는 실험 결과와 비교되어졌고,이를 통해 시험된 재료의 최적의 성형조건을 제시하였다.

• Composites Research
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• v.12 no.6
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• pp.31-42
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• 1999

In aerospace industry, the improvement of structural performance of fight structure without increasing weight has great advantage. In this study. an innovative design method to increase the buckling load and tension failure load at the same time without increasing the weight of composite plates was investigated. By using the curvilinear fiber format a method to increase the buckling load and tension failure load simultaneously was investigated for composite plates with central hole with finite element method. It was investigated how much gain can be obtained with curvilinear fiber format for the plates with different hole size and different stacking sequence. And, for the cases studied, the failure mechanism was also investigated. For the manufacturing of the curvilinear fiber format, smoothly and continuously changing fiber path is necessary. In this study, a simple method to find the smoothly changing fiber path by using the fiber angles obtained with finite element method was presented.

• Composites Research
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• v.34 no.2
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• pp.136-142
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• 2021

3D printing technology has the advantage of easy to make various shapes of products without a mold. However, it has a problem such as mechanical properties vary greatly depending on materials and manufacturing conditions. Thus, the need for research of 3D printing technology on ways to reduce manufacturing cost compared to physical properties is increasing. In this study, a 3D printing thermoplastic structure was fabricated using short fiber carbon fiber reinforced nylon filaments. And a method of improving mechanical properties was proposed by reinforcing the outer surface using pultruded continuous fiber-type carbon fiber or glass fiber-reinforced thermosetting composite material. It was confirmed that the bending properties were improved according to the reinforcing position of the stiffener and the type of fiber in the stiffener.

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.613-617
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• 2022

The equipment for fabricating the large-area PTFE nanofiber coated-PTFE foam filter for use as filtration parts of the baghouse that removes particulate matter (PM) in industrial sites was designed and manufactured in this study. The PTFE nanofiber was coated on a commercial PTFE foam filter to increase its PM collection efficiency. The equipment and fabrication processes using a roll-to-roll system were proposed to continuously coat PTFE nanofibers on the surface of the PTFE foam filter. The electrospinning and annealing parts were designed and made by optimizing the equipment for the roll-to-roll system. The surface morphology, composition, and filtration characteristics of the large-area filter fabricated by this equipment were confirmed. PTFE nanofibers were uniformly coated on the large-area filter, and the PTFE nanofiber coated-PTFE foam filter showed PM_2.5 collection efficiency of 91.79% and an appropriate pressure drop of 62 Pa with a face velocity of 1 m/min at 280 ℃.

• Composites Research
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• v.31 no.6
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• pp.317-322
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• 2018

In various industry, the composite is tried to be applied to products and thermoplastic based composite is in the spotlight because this composite can be recycled. The use of continuous fiber thermoplastic (CFT) method increased gradually than long fiber thermoplastic (LFT). In this study, tensile, flexural, and impact test of different array types of glass fiber (GF)/thermoplastic composites were performed to compare with GF array. Impregnation property between GF mat and thermoplastic was determined using computed tomography (CT). At CFT method, thermoplastic film is not wet into GF roving and many voids are appeared into composite. This phenomenon affects to decrease mechanical properties. Plain pattern GF mat was the best mechanical and impregnation properties that distance between two roving was set closely to $100{\mu}m$.