• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.204-209
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• 2001

In this research, the effects of fiber stacking sequence on damage behaviors of FML(Fiber Metal Laminates) subject to indentation loading. SOP (Singly Oriented Ply) FML and angle ply FML were fabricated to study fiber orientation effects and angle ply effects. FML were fabricated by using 1050 aluminum laminate and carbon/epoxy prepreg. To increase adhesive bonding strength, Al laminate was etched using FPL methods. The static indentation test were conducted by using UTM(5ton, Shimadzu) under the 2side clamped conditions. During the tests, load and displacement curve and crack initiation and propagation behaviors were investigated. As fiber orientation angle increases, the crack initiation load of SOP FML increases because the stiffness induced by fiber orientation is increased. The penetration load of SOP FML is influenced by the deformation tendency and boundary conditions. However, the macro-crack of angle ply FML was initiated by fiber breakage of lower ply because angle plies in Angle ply FML prevents the crack growth and consolidation. The Angle ply FML has a critical cross-angle which prevent crack growth and consolidation. Damage behavior of Angle ply FML is changed around the critical cross-angle.

• 한국안전학회지
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• 제20권2호
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• pp.26-31
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• 2005

The strong continuous fiber reinforced metal matrix composites (MMCs) are recently used in aerospace and transportation applications as an advanced material due to its high strength and light weight. Unidirectional fiber-metal matrix composites have superior mechanical properties along the longitudinal direction. However, the applicability of continuous fiber reinforced MMCs is somewhat limited due to their relatively poor transverse properties. Therefore, the transverse properties of MMCs are significantly influenced by the properties of the fiber/matrix interface. In order to be able to utilize these MMCs effectively and with safety, it must be determined their elastic plastic behaviors at the interface. In this study, the interfacial stress states of transversely loaded unidirectional fiber reinforced metal matrix composites investigated by using elastic-plastic finite element analysis. Different fiber volume fractions $(5-60\%)$ were studied numerically. The interlace was treated as three thin layer (with different properties) with a finite thickness between the fiber and the matrix. The fiber is modeled as transversely isotropic linear-elastic, and the matrix as isotropic elastic-plastic material. Using proposed model, the effects of the interface region and fiber arrangement in MMCs on the distributions of stress and strain are evaluated. The stress distributions of a thin multi layer interface have much less changes compared with conventional perfect interface. The analyses were based on a two-dimensional generalized plane strain model of a cross-section of an unidirectional composite by the ANSYS finite element analysis code.

• 전자공학회논문지SC
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• 제49권3호
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• pp.75-81
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• 2012

최근에 소개된 능동 FSS(active frequency selective surface) 또는 ESS(electromagnetic smart screen)는 2차원 금속섬유 복합재료에서 금속섬유의 부하저항을 변화시킴으로써 복합재료의 분산특성을 변경시키는 기술이다. 본 논문에서는 부하저항의 변화에 따른 ESS의 분산특성을 효율적으로 계산하기 위해 GEC(generalized equivalent conductor) 기법을 기반으로 수정하여 적용한다. 부하저항에 따른 ESS의 투과계수와 유효유전율을 1~40 GHz의 범위에서 시뮬레이션 한다. 또한, 부하저항을 변경함으로써 공진주파수와 대역폭을 변경할 수 있음을 보인다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1378-1381
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• 2003

Recently, high-performance composite materials have been used for various industrial fields because of their superior high strength, high stiffness and lower weight. In this study, manufactured fiber reinforced metal laminate materials are composed of two parts. One is hard-anodized A15083-O alloy as a face material and the other is high strength aramid fiber (Twaron CT709) and polyethylene fiber(Dyneema HB25) laminates as a back-up material. Resistance to penetration is determined by protection ballistic limit(V$\sub$50/, a static velocity with 50% probability for complete penetration) test method. V$\sub$50/ tests with 0$^{\circ}$ obliquity at room temperature were conducted with 5.56mm ball projectiles that were able to achieve near or complete penetration during high velocity impact tests.

• 소성∙가공
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• 제6권4호
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• pp.346-356
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• 1997

The fiber orientation distribution and interface bonding in hot extrusion process have an effect on the maechanical properties of metal matrix composites(MMC's). Aluminium alloy matrix composites reinforced with alumina short fibers are fabricated by compocasting method. MMC's billets are extruded at high temperature through conical and curved shaped dies with various extrusion ratios and temperature. This present study was directed to describe the systematic correlation between extrusion die shape and subsequent results such as fiber breakage, fiber orientation and tensile strength to hot extruded MMC's billet. Extrusion load, tensile strength and hardness for variation of extrusion ratios and temperature are investigated to examine mechanical properties of extruded MMC's SEM fractographs of tensile specimens are observed to analyze the fracture mechanism.

• 한국안전학회지
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• 제19권4호
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• pp.25-30
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• 2004

Unidirectional fiber-metal matrix composites have superior mechanical properties along the longitudinal direction. However, the applicability of continuous fiber reinforced MMCs is somewhat limited due to their relatively poor transverse properties. Therefore, the transverse properties of MMCs are significantly influenced by the properties of the fiber/matrix interface. In this study, the interfacial stress states of transversely loaded unidirectional fiber reinforced metal matrix composites investigated by using elastic-plastic finite element analysis. Different fiber volume fractions $(5-60\%)$ were studied numerically. The interface was treated as thin layer (with different properties) with a finite thickness between the fiber and the matrix. The fiber is modeled as transversely isotropic linear-elastic, and the matrix as isotropic elastic-plastic material. The analyses were based on a two-dimensional generalized plane strain model of a cross-section of an unidirectional composite by the ANSYS finite element analysis code.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.407-412
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• 2001

In this research, damage behavior of singly oriented ply (SOP) fiber metal laminate (FML) subject to concentrated load was studied. The static indentation tests were conducted to study fiber orientation effect on damage behavior of FML. During the static indentation tests, Acoustic Emission technique (AE) was adopted to study damage characteristics of FML. AE signals were obtained by using AE sensor with 150kHz resonance frequency and the signals were compared with indentation curves of FML. As fiber orientation angle increases, the crack initiation load of SOP FML increases because the stiffness induced by fiber orientation is increased. The penetration load of SOP FML is influenced by the deformation tendency and boundary conditions. Cumulative AE counts were well predicted crack initiation and crack propagation and AE amplitude were useful for prediction of damage failure mode. During the matrix cracking, fiber debonding and fiber breakage, AE amplitude has $45{\sim}60dB,\;60{\sim}80dB\;and\;90{\sim}100dB$, respectively.

• 한국대기환경학회지
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• 제20권3호
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• pp.361-369
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• 2004

A metal fiber bed has seldom been applied to the practical filtration process despite its excellent mechanical and chemical stability. The filter-bed used in this work was highly porous with open structure, of which apparent porosity was 80 ∼ 90%. Although pressure loss across the filter-bed was very low, separation efficiency was found to be quite high. This paper focuses on the basic filtration mechanisms of a metal filter-bed and a thin ceramic filter from fly ash for reference. The experimental parameters were face velocity, dust loading and porosity of filter-bed. Pressure drop increased with increasing face velocity and dust feeding load for both filters. It also showed that dust particles deposited in the deep flow path, finally resulting in clogging the pore channels. It thereby indicates that the dominating mechanism of the metal filter-bed would be depth filtration. Meanwhile, the thin fly ash composite filters trapped the aerated dust mainly on the surface of the filter medium, so that the instantaneously formed dust layer might cause a steep increase of pressure drop across the filtration system.

• Journal of the Optical Society of Korea
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• 제7권2호
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• pp.84-88
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• 2003

A new method for temperature compensation of fiber Bragg grating (FBG) using hi-metal is proposed and experimentally demonstrated. Bi-metal bends toward the metal of low temperature expansion coefficient as the temperature increases, and this property is utilized to cancel the thermo-optic effect of the fiber. The optimum thickness of the high coefficient metal was empirically found by the trial-and-error method. The temperature sensitivities were 8.1 pm/$^{\circ}C$ and -0.018 pm/$^{\circ}C$ for the uncompensated and compensated FBGs, respectively, which indicates a reduction to a mere 0.22 % of the original sensitivity. No appreciable change in the spectral shape was observed. The packaging technique described in this paper is simple and compact, and it can be used for FBGs in WDM and DWDM communication systems that have stringent requirements on the temperature stability of the components.

• Design & Manufacturing
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• 제17권3호
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• pp.55-60
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• 2023

The fiber-reinforced plastics and cellular injection molding process can be used to efficiently reduce the weight of battery housing components of mild hybrid electronic vehicles(MHEV) made of metal. However, the fiber orientation of fiber-reinforced plastics and the growth of foaming cells are intertwined during the injection molding process, so it is difficult to predict the mechanical properties of products in the design process. Therefore, it is necessary to evaluate the mechanical properties of the materials prior to the efficient stiffness design of the target product. In this study, a study was conducted to evaluated the mechanical properties of fiber reinforced cellular injection-molded specimens. Two types of fiber-reinforced plastics that can be used in the target product were evaluated for changes in tensile properties of cellular injection-molded specimens depending on the foaming ratio and position from the injection gate. The PP and PA66 specimens showed a decrease of tensile modulus and strength of approximately 30% and 17% depending on the foaming ratio, respectively. Also, the tensile strength decreased approximately 26% and 17% depending on the position from the injection gate, respectively. As a result, it was confirmed that the PP specimens have a significantly mechanical property degradation compared to the PA66 specimens depending on the foaming ratio and position.