• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.29-33
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• 2001

In the present study, AZ91Mg/$\textrm{Al}_2\textrm{O}_3$ short fiber+SiC particulates hybrid metal matrix composites(MMCs) were fabricated by squeeze casting method. Different particulate sizes of 45, 29 and $9\mu\textrm{m}$ were hybridized with 5% volume fraction to investigate the effect of SiC particulates size on microstructure, mechanical and thermal properties such as hardness, flexural strength, wear resistance and thermal expansion. Results show that the microstructure of the hybrid composites were quite satisfactory, namely revealing relatively uniform distribution of reinforcements. Some aggregation of SiC particulates caused by particle pushing was observed especially in the hybrid composites containing in fine particulates($9\mu\textrm{m}$). The hardness and flexural strength were improved by decreasing particulates size, whereas wear resistance improved by increasing particulates size because of large particulates restricting matrix wear from contacted stress. Regardless of particulates size, thermal expansion of composites was the same. This may be because the content of particulates was in all cases 5 volume fraction.1

• 대한치과보철학회지
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• 제38권3호
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• pp.366-374
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• 2000

FRC/ceromer system provides the clinician with a durable, flexible, and esthetic alternative to conventional porcelain fused to metal crowns. FRC is the matrix which is silica-coated and embedded in a resin matrix. The ceromer material which is a second generation indirect composite resin contains silanized, microhybrid inorganic fillers embedded in a light-curing organic matrix. FRC/ceromer restoration has a several advantages: better shock absorption, less wear of occluding teeth, translucency, color stability, bonding ability to dental hard tissues, and resiliency. It has versatility of use including inlay, onlay, single crown, and esthetic veneers. With adhesive technique, it can be used for single tooth replacement in forms of inlay adhesion bridge. In single tooth missing case, conventional PFM bridge has been used for esthetic restoration. However, this restoration has several disadvantages such as high cost, potential framework distortion during fabrication, and difficulty in repairing fractures. Inlay adhesion bridge with FRC/ceromer would be a good alternative treatment plan. This article describes a cases restored with Targis/Vectris inlay adhesion bridge. Tooth preparation guide, fabrication procedure, and cementation procedure of this system will be dealt. The strength/weakness of this restoration will be mentioned, also. If it has been used appropriately in carefully selected case, it can satisfy not only dentist's demand of sparing dental hard tissue but also patient's desire of seeking a esthetic restorations with a natural appearance.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2328-2335
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• 2002

A hybrid composite material has many potential usage due to the high specific strength and the resistance to fatigue, when compared to other composite materials such as fiber reinforced plastic(FRP) and metal matrix composite(MMC). However, the fracture mechanism of hybrid composite material is extremely complicated because of the bonding structure of metals and FRP. In this study, Al 7075 sheets and carbon epoxy preprags were used to fabricate the hybrid composite. Recently, nondestructive technique has been used to evaluate the fracture mechanism of these composite materials. AE technique was used to clarify the microscopic damage behavior and failure mechanism of A17075/CFRP hybrid composite. It was found that AE paralneters such as AE event, energy and amplitude were effective to evaluate the failure process of Al 7075/CFRP composite. In addition, the relationship between the AE signal and the characteristics of fracture surface using optical microscope was discussed.

• 한국염색가공학회지
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• 제18권4호
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• pp.11-19
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• 2006

Black-dyed PET fabrics were sputtered with stainless steel through DC-magnetron type device to investigate the possibility of coloration effect, and then considered the morphological structure and physical characteristics such as water permeation ability and washing fastness. Change in color was estimated on the basis of CIELAB color system. The color coordination of metal plated PET was shifted to yellow-red from red-blue. Colour difference$({\Delta}E^*)$ was increased by sputtering conditions with increasing ion current and treatment time. Especially, $Lightness(L^*)$ value of PET was remarkably increased by sputtering, whereas $Chroma(C^*)$ increased gradually. From SEM analysis, rough and uneven craters were found and thickened on the fiber surfaces with longer sputtering time. And washing fastness was a little poor and absorption ability slightly decreased. There were little changes of breaking load and breaking extension. It was evident that observed uneven craters in the plated thin layer resulted in the colour change of PET fabrics by sputtering treatments.

• 패션비즈니스
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• 제9권3호
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• pp.114-124
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• 2005

Based on the previous study, three types at synthetic fibers comprising nylon, PET, and acrylic fibers were investigated in this study. The effect at mordanting on the air-permeability and dyeing properties at fabrics was investigated. The effect at rinsing process on the air-permeability and color was quantitatively investigated by rinsing the mordanted fabric specimens 1$\sim$3 times after mordanting. The air-permeability changed peculiarly according to the characteristics of the tiber materials after mordanting. The air-permeability values of nylon and acrylic fabric specimens dropped significantly after mordanting. On the other hand, those of PET fabric specimens hardly changed after mordanting. The metal ions absorbed on the fibers of nylon and acrylic fabrics did not show the mordanting effect. Regardless of mordanting, cochineal dyestuff made direct links with the molecular chains in nylon fabrics exhibiting dark colors. After dyeing acrylic fabrics, the color did not develop at all, even though partial components of the cochineal dyestuff were absorbed apparently.

• 한국항공운항학회지
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• 제25권4호
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• pp.130-140
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• 2017

Lightning protective design of an aircraft fuel system is closely related to the safety of the flight. Recently, composite material in building an aircraft becomes more important because it can reduce the weight of the aircraft. The composite materials decrease the protection against the effect of lightning. Lightning protective design of metal material aircraft has been researched for a long time and the design technique has been announced widely. However, research on the lightning protective design using composite material aircraft is very limited. In this study, lightning protective design for fuel tank structural component, access cover, fuel filler cap and drain valve in carbon fiber composite material aircraft have been presented. To show the compliance with FAA airworthiness standard regarding the presented protection designs, three steps, including lightning strike analysis, lightning environment analysis and certification test, were conducted in accordance with FAA AC 20-53.

• 한국정밀공학회지
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• 제20권1호
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• pp.205-213
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• 2003

The fiber reinforced composite material is widely used in the multi-industrial field where the weight reduction of the infrastructure is demanded because of their high specific modulus and specific strength. It has two main merits which are to cut down energy by reducing weight and to prevent explosive damage preceding to the sudden bursting which is generated by the pressure leakage condition. Therefore, Pressure vessels using this composite material in comparison with conventional metal vessels can be applied in the field such as defense industry, aerospace industry and rocket motor case where lightweight and the high pressure are demanded. In this paper, for nonlinear finite element analysis of E-glass/epoxy filament winding composite pressure vessel receiving an internal pressure, the standard interpretation model is developed by using the ANSYS, general commercial software, which is verified as the accuracy and useful characteristic of the solution based on Auto LISP and ANSYS APDL. Both the preprocessor for doing exclusive analysis of filament winding composite pressure vessel and postprocessor that simplifies result of analysis have been developed to help the design engineers.

• 한국산학기술학회논문지
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• 제4권3호
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• pp.199-203
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• 2003

In this study plastic optical fibers (POFs) were considered as light-transmitting media and substrates for the potential use in photocatalytic environmental purification system. After the characteristics of POFs in terms of light transmittance and absorption were determined at the beginning, the further investigation was performed through the photocatalytic degradation of trichloroethylene (TCE), iso-propanol and etc. with TiO$_2$-coated optical fiber reactor systems (POFR). It is concluded that the use of POFs is preferred to quartz optical fibers (QOFs) since the advantages such as ease of handling, lower cost, relatively reasonable light attenuation at the wavelength of near 400nm can be obtained. Various geometrical reactor shapes have been constructed and applied for the last one and half years. For the use of POF in water phase treatment, however, more detailed scientific and engineering aspects should be envisaged. This case requires a suitable mixture to obtain more stable and innocuous immobilization of photocatalyst on POF. To overcome this disadvantage, metal-organic chemical vapor deposition (MOCVD) was conducted in a fluidized bed to deposit thin films of titania on glass and alumina beads. Those can be used as photocatalysis for the removal of pollutants especially in liquid phases.

• Journal of Advanced Marine Engineering and Technology
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• 제35권4호
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• pp.397-405
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• 2011

친환경 대체에너지의 한 분야인 수소에너지는 물의 전기분해와 화석연료의 개질을 통해 얻어 진다. PEMFC용 개질기에 적용 가능한 난류예혼합 방식의 메탈화이버 플랫버너를 제작하였다. 공급열 량에 따른 연소영역의 평균온도분포와 CO, HC, $CO_2$ 및 $O_2$등 각종 화학종의 평균농도로 플랫버너의 화염구조 및 특성을 조사하여 개질기 적용 가능성을 확인하였다. 그리고 PIV 유동실험결과와 유동수 치해석 결과를 비교 분석하여 차후 PEMFC용 개질기 개발에 있어 수치해석을 적용하기 위한 기초연구를 진행하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1312-1316
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• 2007

Strip casted and rolled magnesium sheet is become exiting material for car manufacturer, due to its better formability and specific strength compare with conventional extruded sheet. TWB technology was attractive for car body designer, because it saves the weight of the car without strength loss. In this study, the laser welding performance of magnesium sheet was investigated for Mg TWB panel manufacturing. The material was strip casted and rolled magnesium alloy sheet contains 3 wt% Al and 1 wt% Zn (AZ31). Lamp pumped Nd:YAG laser of 2kW was used and its laser light was delivered by optical fiber of 0.6mm core diameter to material surface with focusing optics of 200mm focal length for TWB welding. The microstructure of weld bead was investigated to check internal defects such as inclusion, porosity and cracks. Also mechanical properties and formability were evaluated for press forming of car body. For the results, there was no crack but inclusion or porosity on weld at some conditions.The tensile strength of weld was over 95% of base metal. Inner and outer panel of engine hood were press formed and assembled at elevated temperature.