• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.125-126
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• 1994

The chemorheological changes and kinetics during curing reaction of an silica filled epoxy system (DGEBA with curing agent Polyxoypropylenediamine) were investigated. This study concentrates on the influence of silica on the reaction kinetics and rheological behavior of the eopxy system. The concentration of the filler was varied 0~200phr. Curing behavior of the silica filled epoxy system was measured at various heating rates with DSC. Conversion was also measured by integrating the obtained DSC curve and Kinetic parameters measured by using the nonlinear regression method. DSC experiments showed that the presence of silica was found to accelerate the progress of the curing reaction and of reduce the heat of reaction compared with that of unfilled epoxy systems . Rheological experiments were conducted on a Physica by using a disposable parallel plate fixture. Material properites were measured such as the elastic modulus(G′), the loss modulus(G"), the loss tangent(tan $\delta$), and the viscosity was at the initial stahe, and the more the silica filler was added, and the lower the gel temperature was in the epoxy system. In this study it is concluded that the curing of the silica filled epoxy system was found to be accelerated, as silica was added to the epoxy compound.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.301-304
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• 2000

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.454-456
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• 2001

본 논문에서는 무선인터넷의 효율적인 컨텐츠 서비스를 위하여 기존 웹 페이지의 HTML(Hypertext Markup Language)을 WML로 변환하기 위해 개발된 기존 제품들에 대한 비교분석을 통하여 효과적인 필터링 기능을 수행하는 시스템을 제안하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.277-281
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• 2003

Effects of $CaF_2$ addition as a filler on the high frequency dielectric properties and sintering of CaO-$Al_2O_3-SiO_2-B_2O_3$(CASB) and ZnO-MgO-$B_2O_3-SiO_2$(ZMBS) glass composites were investigated. The optimal glass composition in the CASB system was 33.0CaO-$17.0Al_2O_3-35.0SiO_2-15.0B_O_3$(in wt%). The corresponding dielectric properties were k=8.1 and $Q{\times}fo$=1,200GHz. The sintering temperature was $800{\mu}m$. In case of 2MBS system, 25.0ZnO-25.0MgO-20.0$B_2O_3-30.0SiO_2$(in wt%) glass showed k=6.8 and $Q{\times}fo$=5,200GHz when it was sintered at $750^{\circ}C$. The maximum amount of $CaF_2$ in the CASB and 2MBS glass system without any detrimental effect on the sintering was 25.0 v/o and 15.0 v/o, respectively. The addition of $CaF_2$ in the glass systems improved the high frequency dielectric properties. In case of CASB+$CaF_2$ composite, k was 7.1 and $Q{\times}fo$ was 2,300GHz. And in case of 2MBS+$CaF_2$ composite, k was 5.9 and $Q{\times}fo$ was 8,100GHz. $CaF_2$ addition also reduced sintering temperature. Effects of $CaF_2$ on the dielectric and sintering properties was analyzed in terms of viscosity and crystallization behavior changes due to the interaction between $CaF_2$ and the glass systems.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.4
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• pp.136-143
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• 2015

It is well known that the use of PCC as a filler for printing paper making brought about the serious deterioration of strength properties of paper, although PCC could be helpful to reduce the energy consumption. The use of modified PCC with NCC was tried to solve and/or reduce the strength deterioration problem. NCC was prepared from SwBKP by the acid hydrolysis. There was no significant changes in chemical properties and crystalline structure. However the cyrstallinity of NCC was higher than those of SwBKP. The different dosage of NCC was applied to modify the properties of PCC. 0.1% of NCC dosage was enough to improve ash retention and paper properties. The use of modified PCC with NCC as a filler improved ash retention, bulk, opacity and formation without the serious deterioration of strength properties. Thus the use of modified PCC with NCC might be helpful for not only reduction of energy consumption but also increase of filler dosage without the significant sacrifice of strength properties by the optimization of retention system.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.822-824
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• 1998

The lithium polymer battery with polymer electrolyte is expected as a safe and long cycle life battery. This paper reports primarily the recent development results of a solid polymer electrolyte, which is a key point of the secondary battery system. The new type of polymer electrolyte was prepared under a dry Ar atmosphere by dissolving $LiCIO_4$ in a matrix of EC, PC and then dispersing polyacrylonitrile(PAN). Also adding some inorganic filler $Al_2O_3$. The dispersed solution heated at $120^{\circ}C$. The polymer electrolyte were characterized by EIS(Electrochemical Impedance Spectroscopy), TGA(Thermo Gravimetric analysis), DMA(Dynamic Mechanical Analyzer), DSC (Differential Scanning Calorimetry). The lithium ion yield is 0.29 when PAN-$Al_2O_3$ which was applied DC 5mV. The ionic conductivity of PAN, PAN-$Al_2O_3$ polymer electrolytes were showed $1.0{\times}10^{-4}S/cm$, $8.4{\times}10^{-4}S/cm$ at room temperature. When inorganic filler was added in the polymer electrolyte, ionic conductivity and lithium yield more larger than without inorganic filler.

• Elastomers and Composites
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• v.49 no.1
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• pp.66-72
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• 2014

Carbon coating on silica particles is done by grafting expanded graphite on the silica aggregates. Successful coating of carbon is corroborated using FT-IR, TGA, XPS and TEM. Crystalline nature of coated graphite is corroborated using XRD. Influence of carbon coated silica particles on rheometric and mechanical properties of SBR composites are investigated. Carbon coated silica particles showed significant improvement in rheometric and mechanical properties, when compared to pristine silica filled system corroborating higher polymer-filler adhesion. This fact was further supported by bound rubber content and equilibrium swelling ratios of unvulcanized and vulcanized SBR composites.

• Elastomers and Composites
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• v.35 no.2
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• pp.132-137
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• 2000

The cure and physical properties of EPDM foam containing ground rubber and carbon black as filler were studied. The cure time reduced with the addition of filler. This result means reducing the operation time. In case of ground rubber was used, blowing ratio, tensile strength, and elongation were decreased rapidly at above 30 phr. On the other hand, in case of carbon black, they showed similar physical properties until 70 phr was used limited to 30 phr to make a good foam, which should be due to low interfacial interaction between EPDM and ground rubber. All the EPDM foams showed excellent thermal stability.

• Journal of Ocean Engineering and Technology
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• v.30 no.4
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• pp.334-340
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• 2016

The combustion chamber of a diesel engine is often exposed to a more serious wear and corrosion environment than other parts of the engine because its temperature increases as a result of using heavy oil of low quality. Therefore, repair and built-up welding methods must be performed on worn or corroded parts of the piston crown, exhaust valve, etc. from an economical point of view. In this study, Inconel 718 filler metal was used in repair welding on the groove of a forged steel specimen for a piston crown, along with built-up welding on the surface of another forged steel specimen. Then, the corrosion characteristics of the weld metal zone for the repair welding and the deposited metal zone for the built-up welding were investigated using electrochemical methods in a 35% H₂SO₄ solution. The deposited metal zone indicated better corrosion resistance than the weld metal zone, showing a nobler corrosion potential, higher impedance, and smaller corrosion current density. It is considered that metal elements with good corrosion resistance were generally included in the filler metal, and these elements were also greatly involved in the deposited meta by built-up welding, whereas the weld metal consisted of metal elements mixed with both the filler metal and base metal elements because of the molten pool produced by the repair welding. Finally, it is considered that the hardness of the weld metal was increased by the repair welding, whereas the built-up welding improved the corrosion resistance of the deposited metal.

• Polymer(Korea)
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• v.31 no.5
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• pp.422-427
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• 2007

Semiconducting layers are thin rubber film between electrical cable wire and insulating polymer layers having a volume resistivity of ${\sim}10^2{\Omega}cm$. Commercial semiconducting layers ire composed of polymer composites reinforced with more than 30 wt% of carbon blacks. A new semiconducting material was suggested in this study based on the carbon nanotube(CNT)-reinforced polymer nanocomposites. CNT-reinforced polymer nanocomposites were prepared by solution mixing and precipitation with various polymer type and dual filler system. The mechanical, thermal and electrical properties were investigated as a function of polymer type and dual filler system based on CNT and carbon black. The volume resistivity of composites was strongly related with the crystallinity of polymer matrix. With the decreased crystallinity, the volume resistivity decreased linearly until a critical point, and it remained constant with further decreasing the crystallinity. Dual filler system also affected the volume resistivity. The CNT-reinforced nanocomposite showed the lowest volume resistivity. When a small amount of carbon black(CB) was replaced the CNT, the crystallinity increased considerably leading to a higher volume resistivity.