• Journal of the Korean Vacuum Society
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• v.19 no.4
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• pp.287-292
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• 2010

We have investigated the effects of oxygen flow ratios on the structural, morphological, and optical properties of AlN thin films grown by using radio-frequency reactive magnetron sputtering. The AlN thin films were deposited at $300^{\circ}C$ of substrate temperature, and the reactive gas were supplied with both nitrogen and oxygen. The oxygen flow ratio was varied by controlling the amount of oxygen with respect to the total mixed gases, 0%, 10%, 15%, 20%, 25%, and 30%. The structural, morphological, and optical properties of the deposited AlN thin films were examined by using X-ray diffractometer, scanning electron microscopy, and ultraviolet-visible spectrophotometer. The AlN thin film grown at 10% of oxygen flow ratio indicated an average transmittance of 91.3% in the wavelength range of 350~1,100 nm and an optical band gap of 4.30 eV. The experimental results suggest that AlN thin films can be deposited optionally by varying the oxygen flow ratio.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.105-110
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• 1998

The propose of this study is to examine the mechanical properties of mortar using ground granulated blast-furnace(GGBF) slag. In this study, the mortar replaced by varying fineness and content of GGBF slag is investigated through the change of compressive strength, chemical resistance and weight loss. As the result, it has been found that GGBF slag increase somewhat higher flow value and compressive strength. In addition, the chemical resistance of motar using GGBF slag shows higher flow that of motar not containing GGBF slag.

• Journal of the Korean Ceramic Society
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• v.23 no.5
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• pp.75-80
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• 1986

The mechanical properties were measured for magnesium phosphate glasses containing small amounts of water. The decrease in hardness with increasing water content was resulted from a looser chain structure caused by water. The fracture of these glasses was changed from brittle fracture to plastic deformation as a results of the increased viscous flow with increasing water contents. The extent of any viscous flow or deformation initiating from the crack tips in these glasses could be considered as quite small.

• The Korean Journal of Food And Nutrition
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• v.4 no.2
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• pp.199-206
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• 1991

Rheological properties of $\alpha$-rice powder were investigated in comparison with those of polished rice powder. Flow behavior for cooked solutions of two powdered samples(5~11%) were Binghampseudo plastic. Consistency index and yield stress of cooked solution of powdered a-rice were much lower than those of polished rice powder while flow behavior index was nearly similar. 9% cooked solution of powdered $\alpha$ -rice showed slightly weaker thixotrophic behavior and more ease tendency to relax under the steady shear than those of polished rice powder.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.583-586
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• 2002

Molding properties of etched surface pattern are presented. Specimens, whose surface patterns are made by print-type etching, are investigated. The molding properties of surface pattern are estimated with roughness deviation of surface pattern on part and mold. The etching properties are related to physical properties of plastic materials and surface roughness of etched pattern. Also, flow mark and gate location can give influence on surface pattern molding. The experimental result can contribute to good molding of surface pattern in injection molding.

• Korea-Australia Rheology Journal
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• v.16 no.3
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• pp.153-160
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• 2004

Open microcellular foams having small-sized cell and good mechanical properties are desirable for many practical applications. As an effort to reduce the cell size, the microcellular foams combining viscosity improvers into the conventional formulation of styrene and water system were prepared via high internal phase emulsion polymerization. Since the material properties of foam are closely related to the solution properties of emulsion state before polymerization, the flow behavior of emulsions was investigated using a controlled stress rheometer. The yield stress and the storage modulus increased as viscosity improver concentration and agitation speed increased, due to the reduced cell size reflecting both a competition between the continuous phase viscosity and the viscosity ratio and an increase of shear force. Appreciable tendency was found between the rheological data of emulsions and the cell sizes of polymerized foams. Cell size reduction with the concentration of viscosity improver could be explained by the relation between capillary number and viscosity ratio. A correlative study for the cell size reduction with agitation speed was also attempted and the result was in a good accordance with the hydrodynamic theory.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.58-63
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• 1999

Almost all concrete structures have many inevitable cracks for various reasons such as drying shrinkage, heat liberation of cement, fatigues or repeating loads and movements. Conventionally, they are repaired with epoxy materials. The Epoxy resins used by repair materials are different from properties of the base concrete materials such as thermal and mechanical properties - thermal expansion coefficients, bending strength. And the epoxy resin cannot release the water inside the concrete structure and cause corrosion of the steel bars. In this study, before the experiment got launched, we had analyzed cement and slag. Then We blended the two grades of ultra fine cement using high blaine cement and slag. And the cement slurry was produced by water and suprplasticizer to each blended ultra fine cement in various conditions. The slurry produced by each conditions was evaluated with flow properties such as viscosity, dropping time, segregation and observation of dry surface after injection.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.657-661
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• 2009

In this study, rheological properties of cement pastes containing ground Finex-slag (4000, 6000, 7000 c$m^2$/g) were investigated bymini-flow test and coaxial cylinder viscometer. And also blast furnace slag(4000, 6000, 7000 c$m^2$/g) were used for comparison. According to the experimental results, Finex-slag and blast furnace slag showed very similar trend in the rheological properties of the cement pastes. The fluidity of cement pastes blended Finex-slag and blast furnace slag powder were improved by high replacement ratio. In the relationship of plastic viscosity and yield stress appeared the tendency of the proportion greatly. And in the relationship of plastic viscosity, yield stress and mini-flow appeared the tendency of the inverse proportion.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.2
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• pp.25-32
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• 2003

Molding properties of etched surface pattern are presented. Injection molding has given attention on improving dimensional accuracy and productivity. However, the molding of etched surface pattern on plastic parts is not researched relatively for its additional values, which can meet design function and customer's attraction. Specimens, whose surface patterns are made by print-type etching, are investigated. The molding properties of surface pattern are estimated with roughness deviation of surface pattern on part and mold. The etching properties are related to physical properties of plastic materials and surface roughness of etched pattern. Also, flow mark and gate location can give influence on surface pattern molding. The experimental result can contribute to good molding of surface pattern in injection molding.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.374-377
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• 2009

Glass fiber reinforced nylon has been used in many plastic industries. Mechanical properties of reinforced plastics depend upon types of glass fiber as well as loading of glass fiber. Tensile properties of glass fiber reinforced nylon66 have been studied for different glass fiber types and sizes. Types of glass fibers were circular and flat, and diameters were 7, 10, and 13 micrometers. Orientations of glass fibers in the matrix of nylon66 have been analyzed through X-ray CT. Tensile specimens were prepared by cutting out of square plates of $100{\times}100{\times}3mm$ with different angles such as 0, 45, and $90^{\circ}$ to the flow direction. As the loading of glass fiber increases to 45 wt% tensile strength increases up 2.5 times compare with neat nylon66. Anisotropic tensile strength has been observed and minimum tensile strength was measured in the specimen cut from perpendicular to the flow direction.