• Carbon letters
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• 제19권
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• pp.47-56
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• 2016

In this study, the fracture behavior of a thermoplastic-modified epoxy resin reinforced with continuous carbon fibers for two levels of fiber-matrix adhesion was performed. A carbon fiber with commercial sizing was used and also treated with a known silane, (3-glycidoxy propyl trimethoxysilane) coupling agent. Toughness was determined using the double cantilever test, together with surface analysis after failure using scanning electron microscope. The presence of polysulfone particles improved the fracture behavior of the composite, but fiber-matrix adhesion seemed to play a very important role in the performance of the composite material. There appeared to be a synergy between the matrix modifier and the fiber-matrix adhesion coupling agent.

• Journal of the Korean Wood Science and Technology
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• 제18권2호
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• pp.16-24
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• 1990

아세틸화(化) 고분자(高分子) 축합(縮合)탄닌의 젤침투 크로마토그래피 분석(分析)을 위해 일반적(一般的)으로 사용(使用)되고 있는 폴리스타이렌 표준물질(標準物質)은 부정확(不正確)한 교정(矯正)값을 준다. 한편 유도체화 하지않은 축합탄닌의 젤침투 크로마토그래피는 폴리스타이렌 디비닐벤젠 코폴리머 컬럼과 디메틸 포름아미드를 용매(溶媒)로 사용(使用)하여 매우 만족스럽게 분석(分析)될 수 있었다. 그 컬럼의 교정은 유도처리 되지않은 고분자(高分子) 축합(縮合)탄닌을 이용(利用)하여 수행되었으며 고분자 탄닌을 유도처리 할 필요가 없으므로 탄닌의 신속한 분자량(分子量) 결정(決定)이 가능하고 컬럼 크로마토그래피로 분리(分離)되어지는 탄닌을 연속적으로 분석(分析)할 수 있는 장점(長點)을 가진다.

• Computers and Concrete
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• 제13권3호
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• pp.389-409
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• 2014

Precast hollow core slabs (HCS) are technically advanced products in the precast concrete industry, widely used in the last years due to their versatility, their multipurpose potential and their low cost. Using three dimensional FEM (Finite Element Method) elements, this study focuses on the stresses induced by the prestressing of steel. In particular the investigation of the spalling crack formation that takes place during prestressing is carried out, since it is important to assure the appropriate necessary margins concerning such stresses. In fact, spalling cracks may spread rapidly towards the web, leading to the detachment of the lower part of the slab. A parametric study takes place, capable of evaluating the influence of the tendon position and of the web width on the spalling stress. Consequently, after an extensive literature review on the topic of soft computing, an optimization of the HCS is performed by means of Genetic Algorithms coupled with 3-D FEM models.

• Wind and Structures
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• 제15권3호
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• pp.247-261
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• 2012

Some numerical investigations are presented concerning the response of a given plate under turbulence driven excitations. Three different input loads are simulated according to the wall pressure distributions derived from the models proposed by Corcos, Efimtsov and Chase, respectively. Modal solutions (finite element based) are used for building the modal stochastic responses in the sub-critical aerodynamic frequency range. The parametric investigations concern two different values of the structural damping and three values of the boundary layer thickness. A final comparison with available experimental data is also discussed. The results demonstrate that the selection of the adequate TBL input model is still the most critical step in order to get a good prediction.

• Archives of Plastic Surgery
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• 제47권6호
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• pp.629-630
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• 2020

• Steel and Composite Structures
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• 제9권3호
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• pp.275-301
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• 2009

The long-term behaviour of simply supported composite steel-concrete beams with deformable connectors subjected to skew bending and torsion is presented. The problem is dealt with by recurring to the displacement method, assuming the bending and torsional curvatures and the longitudinal deformations of each sectional part as unknowns and obtaining a system of differential and integro-differential equations. Some solving methods are presented, in order to obtain exact and approximate solutions and evaluate the precision of the approximate ones. A case study is then presented. For the sake of clearness, the responses of the composite beam under loads applied in different directions are studied separately, in order to correctly evaluate the effects of each load condition.

• 천문학회지
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• 제40권4호
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• pp.141-145
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• 2007

Here we analyze if the ionized shells associated with giant HII regions represent the progenitors of the larger neutral hydrogen supershells detected in the Milky Way and other spiral and dwarf irregular galaxies. We calculate the evolutionary tracks that 12 HII shells found by Relano et al. (2005, 2007) would have if they expanded into the interstellar medium because of multiple supernovae explosions occurring inside the cavity. We find, contrary to Relano et al. (2007), that the evolutionary tracks of these HII shells are inconsistent with the observed parameters of the largest and most massive neutral hydrogen supershells. Thus, an additional energy source to the multiple supernovae explosions is required in order to explain the origin of the most massive neutral hydrogen shells.

• 건축역사연구
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• 제1권2호
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• pp.183-199
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• 1992

The problem of separation between the teaching and the practice of architectural design in Korean universities has activated this study. Comparison between two professor-architects in Italy through their various activities has been made during the period of 1991-1992 in the Istituto Universitario di Architettura di Venezia. The names of the two professor-architects are Aldo Rossi and Franco Mancuso. Their teaching activities in their architectural design class with their assistants, their background and formation of architectural theory, and two realized (and prized) works of them have been compared. The results show that there is a great difference (or oppositions) in their world-view and their attitudes towards architecture, the one as an empiricist, the other as a rationalist. But the most impressive observation must be the fact that all of them were coherent in their teaching, theory and practice, although this raises another qustion about the 'rationality' in architecture.

• Advances in aircraft and spacecraft science
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• 제6권6호
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• pp.463-478
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• 2019

The present work investigates the effect on the flow-induced vibrations of the lay-up sequence of composite laminated axisymmetric structures, using an hybrid approach based on a wave finite element and a transfer matrix method. The structural vibrations, under deterministic distributed pressure loads, diffuse acoustic field and turbulent boundary layer excitations, are analysed and compared. A multi-scale approach is used for the dynamic analysis of finite structures, using an elementary periodic subsystem. Different flow regimes and shell curvatures are analysed and the computational efficiency is also discussed.

• Fibers and Polymers
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• 제7권2호
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• pp.105-111
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• 2006

Coating the fibre surface by in situ oxidative chemical polymerisation of polypyrrole (using $FeCl_3$ as oxidant) is a readily industrial applicable way to give electrical properties to wool with good ageing stability [1], although pre-treatments are required to avoid damage of the cuticle surface due to the acidic condition of the process. FT-IR and EDX analysis reveal that organic sulphonates and sulphates, used as dopants, are absorbed by wool, while chlorine ions are preferably embedded on the polypyrrole layer. The resulting electrical conductivity seems mainly due to the presence of chlorine as counter-ion of polypyrrole; nevertheless, the presence of arylsulphonate in the polymerisation bath increases the electrical conductivity of the coating layer.