• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.172-176
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• 1999

에폭시 수지의 강인성 향상을 위하여 양말단에 아민 반응기를 가지는 PES-CTBN-PES triblock copolymer를 합성하여 이를 에폭시 수지의 강인화제로 사용하였으며 경화제로는 p-DDS(p-dichlorodiphenylsulfone)를 사용하였다. 또한 공중합체에 의한 물성 향상효과를 CTBN과 PES-NH$_2$의 블렌드에 의한 경우와 비교하였다. 강인화된 에폭시 수지의 물성은 강인성 및 굴곡특성을 측정하여 분석하였으며, 열특성은 DSC, TGA, 및 DMA에 의해 실시되었다. 그리고 강인화된 에폭시 수지의 강인성 향상 mechanism을 규명하기 위하여 파단면을 SEM으로 분석하여 상분리 거동을 고찰하였다. 높은 유리전이온도와 우수한 기계적 물성을 가지는 고성능 기능성 폴리설폰(PES-NH$_2$)과 상용 액상 고무 첨가제인 CTBN을 이용하여 합성된 공중합체를 강인화제로 사용함으로써 열안정성, 탄성률 및 내식성의 감소없이 에폭시 수지의 쳐대 단점인 강인성을 최적 수준으로 개선시킬 수 있었으며 공중합체의 에폭시 수지에 대한 우수한 용해도에 따른 가공성이 향상되었다.

• Polymer(Korea)
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• v.32 no.1
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• pp.31-37
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• 2008

The effect of MMT on mechanical properties of CTBN toughened epoxy nanocomposite is studied. In case of CTBN toughened epoxy nanocomposite with modified MMT, it is found that the enhancement of toughness and tensile properties are exhibited in CTBN toughened epoxy nanocomposite with modified MMT From the results of fractured surface morphology of sample, it is clearly shown that the improved mechanical properties can be obtained in CTBN toughened nanocomposite due to the significant energy dissipation mechanism by MMT loading.

• Journal of Adhesion and Interface
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• v.16 no.3
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• pp.101-107
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• 2015

Epoxy resin toughening agents such as core/shell nanoparticles, CTBN epoxy, polyester polyols, and polyurethane have been widely used in order to compensate for the brittleness and improve the impact resistance of the epoxy resin. In this work, a few tougheners mentioned above were individually added into adhesive compositions to observe the effects of physical and mechanical properties. Both flexural strength and flexural modulus were measured with UTM while impact strength was analyzed with Izod impact tester. The obtained results showed that the addition of toughening agents afforded positive performance in terms of flexibility and impact resistance of the cured epoxy resin. Furthermore, DMA experiments suggested that the trends of storage modulus data of each epoxy resin composition coincided with the trends of flexural modulus data. FE-SEM images showed that toughening agents formed circled-shape particles when it was cured in epoxy resin composition at high temperature by phase separation. The existence of particles in the cured samples explains why epoxy resin with toughener has higher impact resistance.

• Polymer(Korea)
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• v.25 no.2
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• pp.246-253
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• 2001

Amino terminated PES-CTBN-PES triblock copolymer was synthesized from PES oligomer and commercial CTBN rubber (CTBN1300$\times$13), and molecular weight of the copolymer was controlled to be 15000 g/mole. The copolymer was utilized to toughen diglycidyl ether of bisphenol-A (DGEBA) epoxy resin which was cured with 4,4'-diaminodi-phenylsulfone (DDS) and subjected to the measurement of thermal properties, fracture toughness ( $K_{IC}$), flexural properties and solvent resistance. The properties were compared with those from the samples modified by CTBN/PES blends. The maximum loading of copolymer into the epoxy resin was 40 wt% without utilizing solvent, at which $K_{IC}$ fracture toughness of 2.21 MPa${\cdot}m^{0.5}$ was obtained without sacrificing flexural properties and chemical resistance. However, the epoxy resin modified with PES/CTBN blend exhibited much lower $K_{IC}$ and flexural properties compared to the epoxy resins toughened by PES-CTBN-PES copolymers.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.447-455
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• 1993

• Journal of Adhesion and Interface
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• v.3 no.4
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• pp.19-26
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• 2002

In order to study the toughening mechanism of rubber modified polycarbonate, the sequence of development of micro-voids was investigated by real-time small angle X-ray scattering with Synchrotron radiation (SR-SAXS). The used test method was wedge test. The scattering intensity increases with increasing penetration depth of wedge, i.e. applied strain. The increase is due to the micro-void formation during deformation. This micro-void was uniformly developed in matrix and was different from large-void due to internal cavitation of rubber particle and/or debonding between rubber particle and polycarbonate matrix. The micro-void was developed at the critical strain and the radius of micro-void is around $600{\AA}$. Above the critical strain the size of micro-void remains almost constant with increasing applied strain. However, the population of micro-void increased with applied strain.

• Composites Research
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• v.18 no.3
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• pp.31-37
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• 2005

In this work, poly(ethylene oxide) (PEO) nanofibers were fabricated by electrospinning to prepare the nanofibers-reinforced composites. And the PEO powders-impregnated composites were also prepared to compare the mechanical interfacial behaviors of the composites. Morphology and fiber diameter of PEO nanofibers were determined by SEM observation. Mechanical interfacial properties of the composites were investigated in fracture toughness $(K_{IC})$ and interlaminar shea. strength (ILSS) tests. As a result, the fiber diameter was decreased with increasing the applied voltage. And optimum condition for the fiber formation was 15 kV, resulting from increasing of jet instability at high voltage. The PEO-based nanofibers-reinforced epoxy composites showed the improvements of both $K_{IC}$ and ILSS, compared to the composites impregnated with PEO powders. These results indicated that the nanofibers had higher specific surface area and larger aspect ratio than those of the powders, which played an important role in improving the mechanical interfacial properties of the composites.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.25-27
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• 2011

본 논문에서는 이미지 블록의 평균 픽셀 값 특성을 양자화 인덱스 변조 기법에 적용하여 이미지 포맷변환에 강인한 정보은닉 기법을 제안한다. 포맷변환에 강인한 이미지 속성은 정규화된 픽셀 히스토그램에 기반하여 분석되며, 그 중 평균 픽셀 값을 통해 정보은닉 알고리즘이 구성된다. 평균 픽셀 값을 양자화 인덱스 변조기법에 적용하기 위한 방안으로 DCT 계수를 정규화 하는 방법이 선택되며, 추출 성공률을 높이기 위해 오류정정부호가 사용된다. 따라서 본 논문의 알고리즘을 통해 결합 이미지가 압축, 사이즈 변화 등의 과정을 거치게 될 경우 발생하는 문제점을 극복할 수 있다.

• Proceedings of the Materials Research Society of Korea Conference
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• 1995.11a
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• pp.57-57
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• 1995

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.172.1-175
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• 1999