• Journal of the Korean Wood Science and Technology
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• 제52권4호
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• pp.301-318
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• 2024

Contrary to other materials like metals, glass, etc., wood continuously interacts with the environment, increasing and decreasing its moisture content according to the humidity of the air and changing its dimensions by swelling or shrinking. Water diffusion through laminated solid wood is crucial in wood bonding processes. The adhesive layer might block the diffusion if the water vapor diffusion is perpendicular to the bond line. As a result of this blockage, different proportions of deformation appear on the two sides of the bond line, which causes stresses in the bonded assembly. The question arises of how long the bonded structure will keep its integrity due to moisture diffusion blockage, inevitable tensions appearing in the glue line, and how these stresses could be avoided. With cross laminated timber (CLT) solid wood panel production, this question gains new importance. Despite the relevance, only a limited number of publications are available. Comprehensive research would also be necessary considering both the molecular structure and diffusion properties of the adhesive adjusted to the wood species (covering possible substituting wood species, too). Overall, this review serves as a resource for enhancing our understanding of water vapor diffusion through wood adhesive layers and provides insights that have implications for reducing stresses in bonded wood assemblies and the performance of the bonded group over time. Furthermore, identifying knowledge gaps is necessary to establish the basis for investigating the diffusion property of CLT panels.

• International Journal of Safety
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• 제1권1호
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• pp.7-12
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• 2002

This paper demonstrates the impact stresses and wave propagation characteristics of glass/epoxy laminates subjected to the low-velocity impact by a steel ball theoretically and experimentally. A plate finite element model in conjunction with experimental contact laws is used for the theoretical investigation. The specimens for statical indentation and impact test are composed of $[0/45/0/-45/0]_28 and [90/45/90/-45/90]_28$ stacking sequences and have clamped-simply supported boundary conditions. Finally, these two results are compared and then the impulsive stress and wave propagation characteristics of this laminated composite are studied.

• Structural Engineering and Mechanics
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• 제51권1호
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• pp.111-130
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• 2014

The aim of this study is to investigate the effects of the beam aspect ratio(L/h), hole diameter, hole location and stacking layer sequence ($[0/45/-45/90]_s$, $[45/0/-45/90]_s$ and $[90/45/-45/0]_s$) on natural frequencies of glass/epoxy perforated beams under room and high (40, 60, 80, and $100^{\circ}C$) temperatures for the common clamped-free boundary conditions (cantilever beam). The first three out of plane bending free vibration of symmetric laminated beams is studied by Timoshenko's first order shear deformation theory. For the numerical analyses, ANSYS 13.0 software package is utilized. The results show that the hole diameter, stacking layer sequence and hole location have important effect especially on the second and third mode natural frequency values for the short beams and the high temperatures affects the natural frequency values significantly. The results are presented in tabular and graphical form.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.710-715
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• 1997

This paper deals with the analysis of the optimum value of honeycomb core considering variable design parameter. As thickness and height of core rises in design parameter, natural frequency of laminated composite plate increases. The angle-phy has the maximum value when the plate of honeycomb core join to opposite direction. This paper shows that the natural frequency of CFRP was higher than that of GFRP and mode shapes were various at angle-ply.

• 대한기계학회논문집
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• 제15권3호
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• pp.713-722
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• 1991

본 연구에서는 graphite/epoxy와 glass/epoxy 그리고 graphite/epoxy와 kevl- ar/epoxy의 혼합적층된 복합재료 평판의 저속충격에 대한 응답을 유한요소 모델을 사 용하여 수치해석 한후, 각각의 단일적층판들의 결과와 비교하였으며, 이때의 접촉력 관계식은 Yang과 Sun이 제안한 수정된 접촉법칙을 이용하였다. 또한, 수치해석 결과 에서의 충격자의 속도변화로써 혼합적창판 배열에 따른 에너지 흡수율을 계산하였고, 이를 충격특성이 취약한 graphite/epoxy 단일 적층판의 결과와 비교 고찰하였다.

• Journal of the Korean Wood Science and Technology
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• 제42권5호
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• pp.571-578
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• 2014

As a way of developing wooden joint development, a glass fiber reinforced wood plate was manufactured to replace a steel plate. Also, the fracture toughness was evaluated. Through application to a cantilever-type specimen made of a column and a beam, the moment resistance performance was evaluated. For the fracture toughness specimen of the wood plate, 12 types were manufactured by varying the combination of a main member (veneer and plywood) and reinforcement (glass fiber sheet and glass fiber cloth). The results of the fracture toughness test indicated that the 5% yield load of the specimen using plywood was 18% higher than that of the specimen using veneer, and that the specimen reinforced by inserting glass fiber sheets between testing materials (Type-3-PS) had the highest average 5% yield load 4841 N. Thus, a moment resistance strength test was performed by applying Type-3-PS to a column-beam joint. The results of the test indicated that compared to the specimen using a steel plate and a drift pin (Type-A), the maximum moment ratio of the specimen using a glass fiber reinforced wood plate (Type-3-PS) and a drift pin (Type-B) was 0.79; and that a rupture occurred in the wood plate due to high stiffness of the drift pin. The maximum moment ratio of the specimen using a glass fiber reinforced wood plate (Type-3-PS) and a glass fiber reinforced wooden laminated pin (Type-C) was 0.67, which showed low performance. However, unlike Type-A, a ductile fracture occurred on Type-C, and the load gradually decreased even after the maximum moment.

• 한국해양공학회지
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• 제28권4호
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• pp.351-355
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• 2014

Today, carbon fibers are used as heating elements. Carbon fibers are generally used to reinforce composite materials because they are lightweight and have a high strength and modulus. Carbon fiber reinforced composite materials are used for aerospace, automobile, and wind turbine blade applications. This work explored the possibility of using carbon fiber reinforced composite materials as self heating materials. The temperatures of the carbon fiber reinforced composites were measured. These results verified that the carbon fiber reinforced composite materials could be used as heating elements. A glass fiber was laminated using various methods. The thermal characteristics of the composites were evaluated. This confirmed that the generation of heat varied according to the lamination thicknesses of the carbon fiber and glass fiber. As the number of carbon fiber laminations increased, the heat-generating temperature increased. In contrast, as the number of glass fiber laminations increased, the amount of heat decreased. The generation of heat and ability to remain warm could be controlled by controlling the carbon fiber and glass fiber laminations.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.64-64
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• 2010

This paper presents the results of changes of optical properties of front materials in crystalline PV modules. If PV modules on the outdoor, transmittance of front materials is reduced by solar light. That is UV, IR included Solar spectrum will have change the properties of glass. Therefore decrease in transmittance leads to loss of the PV modules output. All the PV modules showed the loss in Isc by 1~5% within few hors. To investigate the changes we are analyzed using spectrophotometer from raw glass to laminated glass.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.756-759
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• 2007

We have fabricated pentacene OTFT on ultra-thin flexible polyimide film with a rigid glass support. Polyimide film of the thickness of $10{\mu}m$ has formed on glass by spin coating from the solution. After the entire OTFT process, the OTFT exhibited a fieldeffect mobility of $0.4\;cm^2/Vs$, an $I_{on}/I_{off}$ ratio of $10^7$ and a subthreshold swing of 0.7 V/dec. The OTFT on polyimide film has been detached from the glass support and laminated on a plastic support of $130\;{\mu}m-thick$ PET film. After the detach process, in spite of the degrading of its field-effect mobility, the OTFT showed high $I_{on}/I_{off}$ as high $as{\sim}10^6$.

• 한국해양환경ㆍ에너지학회지
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• 제16권1호
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• pp.53-59
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• 2013

1990년대 이후, 중소형 폐 선박으로부터 생성되는 FRP를 재활용하기 위한 방법으로 층상으로 배열된 로빙층과 매트층을 분리하는 것은 친 환경적이면서도 경제적 재활용의 장점을 가지고 있다. 그러나 효율적으로 로빙층과 매트층을 분리하는 기술과 로빙층은 매트층에 비해 얇은 두께로 존재한다는 이유로 인해 로빙층을 매트층과 분리할 때 기계가 자동적으로 층간의 차이를 인식하는 방법은 아직 개발이 이루지지 않고 있다. 본 연구에서는 유리의 구성비가 다른 두 층의 화학적 성질의 차를 이용하여 광학적으로 층간 인식이 가능한 방법을 모색하였다. 또한 다양한 로빙층의 구성에도 자동적으로 절단위치를 분석하는 절단시스템과 최종생산물의 유용성을 확보할 수있는 다양한 크기의 유리섬유를 생산할 수있는 세단기를 개발하였다. 본 연구 결과로 광학적 인식기술과 유연한 절단기술 그리고 다양한 세단기술이 융합된 폐 FRP의 분리 공정의 단순화와 자동화를 달성하게 되었다.