• Journal of Ship and Ocean Technology
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• v.9 no.1
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• pp.27-37
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• 2005

An experimental study has been carried out as a basic research for the development of the friction drag reduction technology for water-borne vehicles by injecting microbubbles or polymer solution. Experimental apparatus and procedures have been devised and prepared to measure the changes of the wall friction with the injection of additives and the basic experimental data on friction drag reduction are obtained for fully developed channel flows. The effects of key controlling parameters were investigated for higher drag reduction with varying the concentration and the injection rate of additives. The frictional drag has been reduced up to $25\%$ with the microbubble injection and $50\%$ with the polymer solution injection.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.502-504
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• 2009

We demonstrate a pixel-isolated bistable twist-splay namatic (PI-BTSN) liquid crystal (LC) cell which has two stable states of splay and ${\pi}$-twist. Each state is stabilized by a multi-dimensional anchoring effect of pixel-isolating polymer walls without any chiral additives. Polymer walls are formed around the pixel region by anisotropic phase separation between LCs and reactive mesogens. Switching between the two states is archived by using vertical and horizontal electric fields. The memory mode of the fabricated LC cell has shown infinity memory time.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.4
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• pp.505-514
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• 1998

Flow pattern of air-water two phase flow depends on the conditions of pressure void fraction and channel geometry. We classify the flow pattern by measuring the output signal of the conductivity probe. under the classified flow pattern we mount a visualization equipment on the test section and take pictures. We vary the concentration of pure solvent and polymer to measure local void fraction. We know that the maximum point position of local void fraction distribution move from the center of the pipe to the wall of the pipe as JSL increase when JSA is constant in two phase flow. But we find that the maximum point position of local void friction move from the wal of the pipe to the center of the pipe when polymer concentration increase.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.231-232
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• 2019

In this study, primers were prepared by mixing cement and modified polymer, and the adhesion to the substrate surface was enhanced by using cement which is the same material as the basement outer wall. The improved primer is used to verify the adhesion performance of the substrate in wet concrete environments.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.236.2-236.2
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• 2005

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1219-1220
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• 2010

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.251-252
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.299-300
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• 2008

• Transactions of Materials Processing
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• v.19 no.3
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• pp.145-151
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• 2010

In case of thin-wall two-color injection molding, flashing often occurs when molten polymer flows into small gap at the parting line in mold with high pressure or under the unbalanced clamping force condition. In this study, flashing was examined in the production of thin-wall notebook case with large area when the rapid heat cycle molding (RHCM) technology was applied to the two-color injection molding. The effects of the RHCM technology on the part properties and weld-lines were compared with conventional injection molding. The flashing caused by the clamping device of the two-color injection molding machine was examined and compared by experiments and CAE analyses.

• Design & Manufacturing
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• v.11 no.1
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• pp.14-18
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• 2017

Recently, the injection-molded products are lighter, and thinner than ever. In this work, Injection molding simulation was conducted to analysis the filling pattern imbalance in high speed injection molding process for thin-wall injection component, 8 inches LGP. Numerical analysis shows that shear heated polymer near the side wall causes filling imbalance between center and side of cavity. Short shot experiments were conducted and compared with simulation results. Filling imbalance ratio showed a tendency to increase for wider fan gate.