• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2002년도 봄 학술발표회 논문집
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• pp.309-312
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• 2002

The polymer nanocomposites are attracting considerable attention on account of the characteristic properties of nanoparticles have extremely large surface area per a unit mass. Recentry, mica-type silicates like montmorillonite have received a good deal of attention as effective nano-reinforcemen(1), but actually some critical problems such as the difficulties of exfoliation and surface modification, the weak heat-resistance of modifier, and inferior processability due to the increase in melt viscosity have restricted the mass production and various applications of the nanocoposite. (omitted)

• 한국정밀공학회지
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• 제18권8호
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• pp.164-173
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• 2001

The configuration of injection molded part can be classified into primary feature and supplementary feature. Even though supplementary features such as ribs, snap fits and bosses make mold more complicated, which cause the increasement of the mold cost, supplementary features should be attached to primary features because of assembly, reinforcement, moldability and other functional purposes. But it is not easy for novice designers to design them appropriately because of the profound knowledge related to Injection molding. In this paper, the intelligent design tool called ISFD(Intelligent Supplementary Feature Designer) which supplies easy, simple, time and cost-effective design method has been studied and developed. A knowledge-based design system is a new tool which enables the concurrent design and CIM with integrated and balanced design decisions at the initial design stage of injection molding.

• 한국염색가공학회지
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• 제4권3호
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• pp.97-115
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• 1992

In order to improve the processability of rigid rod-like polyspiroacetals without significant loss of their good nature, in this work a few new ideas for molecular design were adopted: (1) Copolymerization for breaking the regularity of polymer repeating units. (2) Incorporation of flexible methylene linkages or spacers in rigid spiroacetal polymer main chain. (3) Derivatization of long flexible side chains onto rigid polymer backbone. On the basis of these ideas, a series of polyspiroacetals were prepared, using the phase transfer catalyst, BTMAC, by interfacial polymerization reactions of spiroacetal monomer (SAB) and disubstituted aromatic acid chlorides or aliphatic diacid chlorides. Physical properties of these polyspiroacetals are discussed in relation to their chemical structure and are compared with those of polyspiroacetals synthesized by several other researchers.

• Current Photovoltaic Research
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• 제2권4호
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• pp.157-167
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• 2014

Colloidal quantum dot (CQD) solar cells have attracted great attention due to their cost-effectiveness and solution-processability, as well as their size-dependent optical and electrical properties. The power conversion efficiency of CQD solar cells has rapidly increased up to ~8.6%, which corresponds to the 3 - 4 fold improvement during the last 3 - 4 years. Up to now, there have been many pioneering results in CQD solar cells. Here, we review the recent progress of CQD solar cells including CQD synthesis strategy and device structure engineering.

• Elastomers and Composites
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• 제34권3호
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• pp.212-221
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• 1999

Mechanical properties of polypropylene filled with recycled rubber dusts obtained from the buffing process in sport shoe sole manufacture were investigated. The use of these dusts eliminates the need for the size reduction process which is usually employed in rubber recycling. Two different waxes, polypropylene wax and ethylene vinyl acetate wax, were used in the PP/rubber dust compound. Two different processes, extrusion and injection moulding, were used to study the influence of the blends on the properties. The waxes gave significant improvement in the shaping of the extrudate. It was found that the impact strength of the injection moulded samples were higher than the extruded samples and the virgin PP. The tensile properties (yield stress and modulus) were dependent on the amount of rubber dust addition. An increase in the rubber dust loading gave lower yield stress and modulus.

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2661-2665
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• 2011

We studied the effect of structural and morphological changes on the conductivity of a stretched conducting polymer film. To improve the poor processability of polyaniline, we used dodecylbenzenesulfonic acid as both a surfactant and a dopant during emulsion polymerization, followed by blending with high-impact polystyrene. UV-Vis/NIR spectra were obtained to observe conformational changes, and SEM and AFM were used to investigate morphological changes. FT-IR dichroism was applied to determine the microscopic orientation, and XRD patterns were obtained for quantitative crystallinity analysis. The electrical conductivity (${\sigma}_{\parallel}/{\sigma}_{\perp}$) was measured as a function of draw ratio. We found a clear correlation between morphological changes and (${\sigma}_{\parallel}/{\sigma}_{\perp}$), especially at the stretching limit. The conductivity of the films can be modified according to the desired application by controlling their structure and morphology.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.52-55
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• 2002

This paper examines the effective thermal conductivity of 3-D braided glass/epoxy composites. 3-D braided composites have a number of advantage over conventional laminate composites, including through-thickness reinforcement, and high damage tolerance and processability. The thermal properties of composites depend primarily on the microstructure of the braided preform and properties of constituent materials. A thermal resistance network model based on structure of the braided preform is proposed by using thermal-electrical analogy. In order to affirm the applicability theses solutions, thermal conductivities of 3-D braided glass/epoxy composites are measured

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.295-298
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• 1997

Recycl ing of PP/EPR based bumper coated with polyester urethane paint has been per formed by chemical decoating method. Electronic Speckle Pattern Interferometry (ESP11 has been applied to characterize the deformation of polyolef in based bumper. In additon, physical properties and processability of recycled materials have been investigated by dynamic mechanical thermal analysis, impact test and melt flower index measurement. The results show that the deformation ratio of recycled material is higher than that of virgin one. The morphological change of EPR, degree of distribution and dispersion during the recycling process seem to be the most important factor for the deformation and the mechanical properties of recycled materials. The experimental results obtained show that ESPI is very powerful technique to study the thermal mechanical property of polyolefin bumper system.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.463-467
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• 2004

This paper presents the fabrication possibility of the micro actuator which uses a micro-thermal bubble, generated b micro-heater under pulse heating. The valve-less micropump using the diffuser/nozzle is consists of the lower plate, he middle plate, the upper plate. The lower plate includes the channel and chamber are fabricated on high processability silicon wafer by the DRIE(Deep Reactive Ion Etching) process. The middle plate includes the chamber and diaphragm d the upper plate is the micro-heater. The Micropump is fabricated by bonding process of the three layer. This paper resented the possibility of the PCR chip operation by the fabricated micropump.

• 한국기계가공학회지
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• 제11권4호
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• pp.173-179
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• 2012

In recent years, Magnesium(Mg) and its alloys have become a center of special interest in the automotive industry. Due to their high specific mechanical properties, they offer a significant weight saving potential in modern vehicle constructions. Most Mg alloys show very good machinability and processability, and even the most complicated die casting parts can be easily produced. In this study, Microstructure, Vickers hardness and tensile tests were examined and performed for each specimen to verify effects of forming conditions. Also to verify upsettability and forming limit of the specimen at room temperature and elevated temperature, upsetting experiments were performed. For comparison, experiments at elevated temperature were performed for various Mg alloy, such as AZ31, AZ91, and AM50. The experimental results were compared with those of CAE analysis to propose forming limit of Magnesium alloys.