• Transactions on Electrical and Electronic Materials
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• 제11권2호
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• pp.69-72
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• 2010

This study investigates the thermal and mechanical properties of insulation elements through the mixing of epoxy based micro and nano particles. Regarding their thermal properties, differential scanning calorimeter and dynamic mechanical analyser were used to calculate the cross-linking densities for various types of insulation elements. The mechanical properties of the bending strength, the shape and scale parameters, were obtained using the Weibull plot. This study obtained the best results in the scale parameters, at 0.5 phr, for the bending strength of the epoxy nano-and-micro mixture composites.

• 대한기계학회논문집
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• 제10권5호
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• pp.724-734
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• 1986

본 연구에서는 타이어의 동적설계의 기초자료를 제시하는데 그 목적이 있다. 해석적 방법으로는 복합막트로이드 유한요소를 이용하여 타이어의 고유진동수 및 진동 모우드를 구하였으며, 그 정확성을 입증하기 위하여 멀디찬널 F.F.T.분소기를 이용한 실험적 결과 및 G.R. Potts의 해석결과와 비교하였다.

• 마이크로전자및패키징학회지
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• 제7권1호
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• pp.41-49
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• 2000

Flip chip assembly on organic substrates using ACAs have received much attentions due to many advantages such as easier processing, good electrical performance, lower cost, and low temperature processing compatible with organic substrates. ACAs are generally composed of epoxy polymer resin and small amount of conductive fillers (less than 10 wt.%). As a result, ACAs have almost the same CTE values as an epoxy material itself which are higher than conventional underfill materials which contains lots of fillers. Therefore, it is necessary to lower the CTE value of ACAs to obtain more reliable flip chip assembly on organic substrates using ACAs. To modify the ACA composite materials with some amount of conductive fillers, non-conductive fillers were incorporated into ACAs. In this paper, we investigated the effect of fillers on the thermo-mechanical properties of modified ACA composite materials and the reliability of flip chip assembly on organic substrates using modified ACA composite materials. For the characterization of modified ACAs composites with different content of non-conducting fillers, dynamic scanning calorimeter (DSC), and thermo-gravimetric analyser (TGA), dynamic mechanical analyzer (DMA), and thermo-mechanical analyzer (TMA) were utilized. As the non-conducting filler content increased, CTE values decreased and storage modulus at room temperature increased. In addition, the increase in the content of filler brought about the increase of $Tg^{DSC}$ and $Tg^{TMA}$. However, the TGA behaviors stayed almost the same. Contact resistance changes were measured during reliability tests such as thermal cycling, high humidity and temperature, and high temperature at dry condition. It was observed that reliability results were significantly affected by CTEs of ACA materials especially at the thermal cycling test. Results showed that flip chip assembly using modified ACA composites with lower CTEs and higher modulus by loading non-conducting fillers exhibited better contact resistance behavior than conventional ACAs without non-conducting fillers.

• 공업화학
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• 제10권1호
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• pp.148-153
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• 1999

2-bromoterephthaloyl chloride와 1,4-bis(p-hydroxybenzoyloxy)butane을 PMMA 용액내에서 중축합시켜 in situ 복합재료를 제조하였다. 이들의 합성확인 및 열적, 기계적 성질은 FT-IR, FT-NMR, DSC와 DMTA에 의해서, 몰폴로지는 광학현미경과 SEM을 사용하여 조사하였다. 합성된 TLCP는 네마틱상을 보였고, 복합재료내 PMMA의 유리전이온도와 기계적 성질은 TLCP의 농도증가와 함께 증가하였다. TLCP domain은 PMMA 매트릭스내에서 미세 분산되었음을 확인하였고 in situ 중합에 의해 제조된 20 wt % TLCP/PMMA 복합재료는 같은 조성의 용액 블렌딩에 의해서 제조된 재료보다 더 높은 기계적 강도와 미세 분산도를 보였다.

• 대한치과보철학회지
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• 제38권6호
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• pp.782-790
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• 2000

The mainly used polymeric material for the denture is PMMA because of its cost and easiness to handle. So it was widely used material among dentists for past decades. But the acrylic-based denture materials have several common weak points such as shrinkage after curing and lack of strength. In order to solve these problems, we adapted one of hybrid system using acrylic polymer and vinyloligosilsesquioxane(POSS). POSS, which is a well known expandable monomer during polymerization process, may eventually suppress volumetric shrinkage. And the hybrid system makes it possible for the polymer to be stable in various severe conditions. Eight different kinds of samples were designed and synthesized. Each samples were characterized with dynamic mechanical analyser(DMA) to confirm their thermodynamic properties, fractured to analyze the cross-sectional morphology of the samples. And elongation, flexural and impact tests were also executed to evaluate the mechanical properties of the samples. From the results, hybrid composites had well defined crosslinked network structure compared to the widely used denture materials, and the mechanical strength improved without changing any surface condition as increment with POSS ratio in hybrid system. Fractured morphology showed homogeneous surfaces in spite of mutli component system, therefore we can conclude that the adoption of the POSS brought the reinforcement of the denture resin.

• Structural Engineering and Mechanics
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• 제87권6호
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• pp.529-540
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• 2023

A novel laminated-hybrid-composite-beam (LHCB) of glass-epoxy infused with flyash and graphene is constructed for this study. The conventional mixture-rule and constitutive-relationship are modified to incorporate filler and lamina orientation. Eringen's non-local-theory is used to include the filler effect. Hamilton's principle based on fifth-order-layer-wise-shear-deformation-theory is applied to formulate the equation of motion. The analogous shear-spring-models for LHCB with multiple-cracks are employed in finite-element-analysis (FEA). Modal-experimentations are conducted (B&K-analyser) and the findings are compared with theoretical and FEA results. In terms of dimensionless relative-natural-frequencies (RNF), the dynamic-response in cantilevered support is investigated for various relative-crack-severities (RCSs) and relative-crack-positions (RCPs). The increase of RCS increases local-flexibility in LHCB thus reductions in RNFs are observed. RCP is found to play an important role, cracks present near the end-support cause an abrupt drop in RNFs. Further, multiple cracks are observed to enhance the nonlinearity of LHCB strength. Introduction of the first to third crack in an intact LHCB results drop of RNFs by 8%, 10%, and 11.5% correspondingly. Also, it is demonstrated that the RNF varies because of the lamina-orientation, and filler addition. For 0° lamina-orientation the RNF is maximum. Similarly, it is studied that the addition of graphene reduces weight and increases the stiffness of LHCB in contrast to the addition of flyash. Additionally, the response of LHCB to moving mass is accessed by appropriately modifying the numerical programs, and it is noted that the successive introduction of the first to ninth crack results in an approximately 40% to 120% increase in the dynamic-amplitude-ratio.

• 대한기계학회논문집
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• 제10권1호
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• pp.110-120
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• 1986

본 45。충돌분사에서는 충돌분류의 평균속도, 난류강도, 난류전단응력등을 측정분석하여 기 연구발표한 자료를 토대로 하여 난류의 충돌배합이 활발히 일어나는 영역(X/X$_{0}$=2,3,4)에서 충돌분류의 특성을 통계학적으로 측정연구코저 한다. 따라서 각방향으로 발생하는 난류성분을 Gauss의 확률분포식과 비교검토하고, 2차원 결합확률정도선도를 측정도시하여 2방향의 난류성분들의 결합난동형상을 온라인 컴퓨 터 시스템에 의하여 분석할 계획이다. 또한 난류성분의 고차모멘트를 측정하여 비대칭도와 편평도등도 연구 구명코저 한다.다.