• Polymer(Korea)
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• v.26 no.3
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• pp.375-380
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• 2002

Diamines (p-phenylenediamine , m-phenylenediamine , and n-hexamethylenediamine) were intercalated into sodium montmorillonite for the further reaction with the anhydride end groups of polyamic acid. The anhydride terminated polyamic acid was synthesized using a mole ratio of 4,4'-oxydianilline : 1,2,4,5-benzene tetracarboxylic dianhydride = 1.50 : 1.53. The modified montmorillonite was reacted with polyamic acid terminated with anhydride group in N-methyl-2-pyrrolidone (polyamic acid/clay nanocomposite). After imidization, thin films of the polyimide/clay nanocomposite were prepared. From the results of XRD and TEM, we found that mono layered silicates were dispersed in polyimide matrix and those resultants were exfoliated nanocomposites. Mechanical properties of exfoliated polyimide nanocomposite were better than both those of pure polyimide and those of intercalated polyimide nanocomposite.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2529-2535
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• 2013

Sol-gel method was utilized to prepare SPEEK/PWA electrolyte composite membranes. TEOS was used as a precursor and phosphotungstic acid(PWA) as a catalyst for the sol-gel reaction. It was observed through FE-SEM analysis that the PWA and silica nanoparticles were uniformly dispersed into the polymer matrix. The water uptake of SPEEK/PWA/silica composite membranes was less affected by TEOS concentration at higher TEOS contents, while the water uptake decreased as TEOS concentration increased at lower TEOS contents. The proton conductivity of the composite membranes showed similar trend as the water uptake of the composite membranes. The methanol permeability of SPEEK/PWA/silica composite membranes decreased as TEOS concentration increased.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.694-695
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• 2007

한국어 문장의 구성은 명사, 동사와 같은 내용어와 조사, 어미와 같은 기능어로 크게 나눌 수있다. 문장의 핵심적인 의미 전달은 내용어에 의해 이루어지며, 한국어 명사구의 경우 잦은 기능어의 생략으로 명사 나열에 의한 복합 명사가 발생된다. 이렇게 발생되는 복합 명사를 구성하는 단위 명사들은 일부 문장 성분을 생략시켜 발생된 것으로, 생략 성분의 복원에 의해 본래의 문장 형태를 추정할 수 있다. 한국어 복합 명사의 경우, 생략되는 문장 성분은 대부분 접사, 조사와 같은 기능어로 국한되며, 기능어의 복원은 단위 명사 간의 격 관계와 의미 관계를 분석하여 이루어질 수 있다. 본 논문에서는 단위 명사간의 보-술 관계를 이용하여 복합 명사를 구성하는 단위 명사 간의 의존 관계를 추정하고, 추정된 의존 관계에 의해 생략된 격조사와 용언화 접사를 복원하는 방법을 제안한다. 구조 분석에서 사용되는 의미 격틀에 의해 결정되는 격 관계는 격조사와 용언화 접사의 복원을 결정하며, 올바른 본래의 문장 표현 복원을 위해 관형격 조사와 관형격 어미를 비롯한 특별한 형태의 복원은 통계 정보와 휴리스틱 규칙으로 결정한다.

• Composites Research
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• v.17 no.4
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• pp.32-39
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• 2004

Among many fiber optic sensors, FBG sensors are being studied more actively than any other sensor due to good multiplexing capabilities. Recently, the application fields of FBG sensors are mainly focused on the composite materials through embedding rather than attaching on the surface. However, there are many limitations on the embedding FBG sensors into composite materials because of the birefringence effects which is induced when FBG sensors are not embedded parallel to the reinforcing fiber. In this study, the fabrication method of FBG sensors with various grating length that are easy to fabricate with good multiplexing capabilities and more stable from the birefringence effects are investigated. The signal characteristics of the FBG sensors are also verified through the cure monitoring of 2 kinds of composite materials.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.347-350
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• 2009

본 연구는 복합운동 유형 순서 변화에 따른 생리적, 생화학적 변화를 비교 하고자 40대 비만여성을 대상으로 12주간 복합운동을 실시하였다. 복합운동 유형은 유산소성 운동과 저항성 운동그룹 그리고 저항성 운동과 유산소성 운동그룹으로 구성하였다. 체지방량의 경우 A그룹의 평균변화량이 B그룹 평균변화량보다 더 많이 감소하였고 통계적으로 유의한 차이를 보였다(p<0.01). 혈당의 경우는 A그룹보다는 B그룹이 더 많이 감소하였으며 통계적으로 유의한 차이를 보였다(p<0.01). 따라서, 비만 중년 여성의 체중감량을 위한 신체구성 변화 유도를 위해서는 복합운동의 순서 변화에 따른 운동유형이 선택적으로 사용되어질 수 있다.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.195-201
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• 2016

In this paper, we present the direction finding accuracy of correlative interferometer method and amplitude-phase comparison method. Spiral antennas are used for amplitude-phase comparison method and blade antennas are used for correlative interferometer method. Those are made for uniform circular array (UCA) direction finding antenna systems. We simulate the accuracy of azimuth angle with 3 antennas UCA when SNR is 20 dB and baseline is 0.5 wave length. Correlative interferometer method has better accuracy than amplitude-phase comparison method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.4 s.74
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• pp.337-345
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• 2006

In this study, to evaluate fatigue characteristics of developed composite bridge deck, compression fatigue test at girder support and flexural fatigue test for the 2.8m-long flexural test model were carried out. For the test specimen, DB 24 truck load was applied up to 2,000,000 cycles. In the compression fatigue test, behavior at deck tube and its bonded connection were evaluated. In the flexural fatigue test, deck behavior at mid-span and girder connection were evaluated.

• Membrane Journal
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• v.6 no.4
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• pp.242-249
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• 1996

To improve pervaporation performance of water/ethanol mixtures, chitosan/poly(vinyl alcohol) blended and phosphorylated chitosan composite membranes were prepared. Chitosan/poly(vinyl alcohol) blends were prepared with various blend ratios and then crosslinked with glutaraldehyde by two methods. With increasing crosslinking agent content and crosslinking times separation factor increased and permeate flux decreased. Separation factor of the membrane which contains glutaraldehyde as a crosslinking agent was higher than that of the membrane surface crosslinked. Phosphorylated chitosan was prepared with various reaction times and composite membrane was prepared. As reaction times increased, the separation factor increased with high affinity for water.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.3
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• pp.123-131
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• 2007

The buckling behavior of a fiber reinforced plastic pipe was researched. When a cylindrical structure is made of isotropic material, it shows two dimensional buckled shape which has same deformed section along the longitudinal direction. But an anisotropic cylindrical structure shows three dimensional buckled shape which has different deformed section along the longitudinal direction. Because the modulus of elasticity is varied in a certain direction when ply angles are changed, the strength of a pipe are changed as ply angles are changed. In this study, the limitation of two dimensional and three dimensional buckling mode was investigated and the buckling strength of a laminated composite pipe was evaluated.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.483-491
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• 2002

This paper summarizes the results of experimental studies concerning the flexural strengthening of reinforced concrete beams by the external bonding of the new reinforcement material, which is composite panel with an advanced fiber sheet bonded on light concrete precast panel. The structural behaviors of strengthened beams are compared with codes in terms of yield load and ultimate load, deflection, flexural stiffness, ductility. Thirty nine large-scale beams were tested experimentally to evaluate the strength enhancement provided by the composite panel. According to the results, it is shown that beams strengthened with composite panel are structurally efficient and that the strength of the strengthened beams are improved comparing with beams strengthened with fiber sheet.