• Journal of Korea Foundry Society
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• v.25 no.2
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• pp.88-94
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• 2005

The microstructure and mechanical property of the ceramic reinforced AC4C matrix composites processed by squeeze casting were investigated. In this study Kaowool and Saffil fiber which are ceramic reinforcements are used as preform materials. As a matrix material, Al-7wt.%Si-0.3wt.%Mg(AC4C) has been used. In case of Kaowool and Saffil/AC4C composites, 7.5 MPa squeezing pressure and minimum 7.0% binder amount are needed to produce sound composite materials. The tensile strength of Kaowool/ AC4C composite is lower than the matrix metal and this can be explained by the melt unfilling due to formed cluster of Kaowool reinforcements. But the mechanical properties of hardness, wear resistance and thermal expansion are better than the matrix materials due to the strengthening effect of ceramic reinforcements.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.3
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• pp.436-442
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• 1997

Corn starch was extruded under relatively low shear, high moisture, and low temperature. Puffing of corn starch dough was induced by injecting $CO_2$gas in the range from 0MPa to 0.09MPa. Piece density and compressive modulus for puffed corn starch were decreased by increasing the injection pressure to 0.07MPa, and increased above 0.07MPa. the microstructure of corn starch puffed with $CO_2$gas showed thick cell size, compared with those puffed with steam. RVA paste viscosity curves of corn starch puffed with $CO_2$had different patterns from those puffed with steam, probably resulted from partial gelatinization of starch. Water absorption and solubility were not significantly changed by $CO_2$injection pressure, but the average degree of polymerization was reduced by higher $CO_2$injection. The water absorption, water solubility, and the average degree of polymerization for corn starch puffed with $CO_2$were significantly lower than those puffed with steam.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1741-1746
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• 2003

Effects of electromagnetic force which is one of the most important factor of metal transfer that affects bead geometry and microstructure of weld metal in GMAW(gas metal arc welding). In this paper, different ways of external electromagnetic forces were applied on GMAW process and their effects on the welding were studied. On certain conditions, better bead geometry, better influence on the arc and metal transfer mode and higher welding efficiency could be obtained. Experimental methods and their results will be presented.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.135.1-135.1
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• 2014

Silicon nanoparticles can be synthesized in a standard radio-frequency glow discharge system at low temperature (${\sim}200^{\circ}C$). Plasma synthesis of silicon nanoparticles, initially a side effect of powder formation, has become over the years an exciting field of research which has opened the way to new opportunities in the field of materials deposition and their application to optoelectronic devices. Hydrogenated polymorphous silicon (pm-Si:H) has a peculiar microstructure, namely a small volume fraction of plasma synthesized silicon nanoparticles embedded in an amorphous matrix, which originates from the unique deposition mechanism. Detailed discussion on plasma synthesis of silicon nanoparticles, growth mechanism and photovoltaic application of pm-Si:H will be presented.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.11.1-11.1
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• 2010

As one of the non-vacuum, low temperature fabrication route, electrochemical synthesis has been focused for pursuing the cost-effective pathway to produce high efficiency photovoltaic devices. Especially the availability to form the thin film structure on flexible substrate would be the great advantage of electrochemical process. The successful synthesis of the most favorable absorber materials such as CdTe and CIGS has been reported by many researchers, however, the efficiency of electrochemically synthesized could not exceed that from vacuum process, because of microstructural controllability and compositional variation on devices. In this study, we represent the effect of process parameters on the microstructure and composition of compound semiconductor during the synthesis, and propose the photovoltaic characteristics of electrochemically synthesized solar cells.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.208-210
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• 2009

5성분계 Ti-Al-Si-C-N 코팅막은 하이브리드 코팅 시스템을 사용하여 실리콘 (Si) 웨이퍼와 SUS 304 기판위에 합성되었다. 본 연구에서는 Si 첨가에 의해 Ti-Al-Si-C-N 코팅막의 미세구조와 기계적 특성의 변화를 체계적으로 조사하였다. Si 함량이 증가됨에 따라 Ti-Al-Si-C-N 코팅막의 미세구조는 주상정에서 나노복합체를 가지는 미세구조로 변화하였다. 나노복합체의 고유한 특성에 의하여 미소경도는 약 56GPa로 증가하였고, Si가 증가함에 따라 평균 마찰계수도 크게 줄어들었다.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.1
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• pp.25-27
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• 2002

To improve the properties of materials for spectacle lens cutting. AIN was included as a sintering additive. The amount of AIN was 0, 1, 3, 5 wt% and materials for spectacle lens cutting were fabricated by hot-pressing at $1830^{\circ}C$ for 2h. Microstructure was consisted of equiaxed SiC and elongated TIC. Typical fracture toughness and hardness of materials for spectacle lens cutting with AIN $4.8MPa{\cdot}m^{1/2}$ and 15.3 GPa, respectively.

• Journal of Powder Materials
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• v.4 no.1
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• pp.26-41
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• 1997

The powder metallurgy (P/M) processed 2009 and 2124 Al composites reinforced with SiC particulates were studied by focusing on the effect of consolidation temperature on the microstructural and mechanical Properties. The mechanical properties such as tensile properties and microhardness of the second phases were analysed in relation to the microstructures observed by a SEM and an optical microscope. The in situ fracture process study using SEM showed that the grain refinement and the removal of manganese-containing particles often observed in the 2124 Al-${SiC}_{p}$ composites were important for the improvement of the mechanical properties. This study offers an optimum consolidation temperature for the control of the manganese-containing particles in the 2124 Al-${SiC}_{p}$ composites that yields mechanical properties higher than those of the 2009 Al-${SiC}_{p}$ composites.

• Journal of Powder Materials
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• v.24 no.1
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• pp.17-23
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• 2017

In this study, a finite element analysis approach is proposed to predict the fluid-structure interaction behavior of active materials for lithium-ion batteries (LIBs), which are mainly composed of graphite powder. The porous matrix of graphite powder saturated with fluid electrolyte is considered a representative volume element (RVE) model. Three different RVE models are proposed to consider the uncertainty of the powder shape and the porosity. P-wave modulus from RVE solutions are analyzed based on the microstructure and the interaction between the fluid and the graphite powder matrix. From the results, it is found that the large surface area of the active material results in low mechanical properties of LIB, which leads to poor structural durability when subjected to dynamic loads. The results obtained in this study provide useful information for predicting the mechanical safety of a battery pack.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.90-91
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• 1998

The influence of gamma-irradiation sterilization on the creep and wear performance of ultra-high molecular weight polyethylene (UHMWPE) was investigated by conducting the dynamic compressive creep tests and pin-on-disc sliding wear tests. The changes of microstructure property, relative crystallinity, oxidation index, percent crosslinking, were also measured and the relationship between these and creep and wear results was discussed.