• 한국전기전자재료학회논문지
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• 제22권5호
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• pp.397-404
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• 2009

Effects of ceramic filler types and dose on the low temperature sintering and dielectric properties of ceramic/$CaO-Al_2O_3-SiO_2$ (CAS) glass composites were investigated. All of the specimens were sintered at $850{\sim}900^{\circ}C$ for 2 h, which conditions are required by the low-temperature co-firing ceramic (LTCC) technology. Ceramic fillers of $CaCO_3$, $Al_2O_3$, $CaCO_3-Al_2O_3$ mixture, and $CaCO_3-Al_2O_3$ compound ($CaAl_2O_4$), respectively, were used. The addition of $Al_2O_3$ yielded the crystalline phase of alumina, which was associated with the inhibition of sintering, while, $CaCO_3$ resulted in no apparent crystalline phase but the swelling was significant. The additions of $CaCO_3-Al_2O_3$ mixture and $CaAl_2O_4$, respectively, yielded the crystalline phases of alumina and anorthite, and the sintering properties of both composites increased with the increase of filler addition and the sintering temperature. In addition, the $CaAl_2O_4$/CAS glass composite, sintered at $900^{\circ}C$, demonstrated good microwave dielectric properties. In overall, all the investigated fillers of 10 wt% addition, except $CaCO_3$, yielded reasonable sintering (relative density, over 93 %) and low dielectric constant (less than 5.5), demonstrating the feasibility of the investigated composites for the application of the LTCC substrate materials.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.177-177
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• 2008

The effect of several $SiO_2-B_2O_3-Al_2O_3$-R(R;Ca, Sr, Ba) borosilicate glass system on sintering behavior, dielectric properties and mechanical properties of glass/ceramic composites were investigated. The amount of '+2 valency' metal elements(Ca, Sr, Ba) were examined in LTCC composite of low k glass with cordierite filler. It was sintered for 60minutes in temperature range from 850C to 950. Properties of frit and glass/ceramic composites were analyzed by DTA, XRD, SEM, Network Analyzer, UTM and so on. Dielectric constant ($\varepsilon_r$) and $Q{\times}f_0$ (Q) of the composite with 50% glass contents demonstrated $\varepsilon_r$ = 5.4 $Q{\times}f_0$ = 1600 GHz. Sintering was complete and maximum bending strength of 160MPa was obtained.

• 한국세라믹학회지
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• 제46권4호
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• pp.413-418
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• 2009

Glass systems based on Ca, Sr, Ba, and Zn modified alumino-boro silicates were investigated in order to improve the dielectric and mechanical properties of a typical LTCC (low temperature co-fired ceramic) which was developed for high frequency highly-integrated modules. The glass was prepared by a typical melting procedure and then mixed with cordierite fillers to fabricate glass/ceramic composite-type LTCC materials. The amount of cordierite filler was fixed at 50 volumetric%. For an optimal glass composition of 7.5% CaO, 7.5% BaO, 5% ZnO, 10% $Al_2O_3$, 30% $B_2O_3$, and 40% $SiO_2$ in mole ratio, the resultant LTCC composite showed a dielectric constant of 5.8 and a dielectric loss ($tan{\delta}$) of 0.0009 after firing at $900^{\circ}C$. An average bending strength of 160MPa was obtained for the optimal composition.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.157-158
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• 2006

A novel nanofabrication process has been developed using two-photon crosslinking (TPC) for the fabrication of three-dimensional (3D) SiCN ceramic microstructures applicable to high functional 3D devices, which can be used in harsh working environments requiring a high temperature, a resistance to chemical corrosion, as well as tribological properties. After sequential processes: TPC and pyrolysis, 3D ceramic microstructures are obtained. However, large shrinkage due to low-ceramic yield during the pyrolysis is a serious problem to be solved in the precise fabrication of 3D ceramic microstructures. In this work, silica nanoparticles were employed as a filler to reduce the amount of shrinkage. In particular, the ceramic microstructures containing 40 wt% silica nanoparticles exhibited relatively isotropic shrinkage owing to its sliding free from the substrate during pyrolysis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.127-128
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.361-362
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• 2012

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 춘계학술발표강연 및 눈문개요집
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• pp.60-60
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• 1999

• Carbon letters
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• 제7권1호
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• pp.27-33
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• 2006

Carbon-ceramic composites were fabricated by using fly ash and PANOX fibers as reinforcement. Fly ash, because of its small size particles e.g. submicron to micron level can be effectively dispersed along with fibrous reinforcements. Phenolic resin was used as carbon precursor. Both dry as well as wet methods were used for forming composites. The resulting composites were characterized for their microstructure, thermal and mechanical properties. The microstructure and mechanical properties of composites are found to be dependent on type of the fly ash, fibrous reinforcements as well as processing parameters. The addition of fly ash improves hardness and the fibers, which get co-carbonized on heat treatment, increase the flexural strength of the carbon-ceramic composites. Composites with dual reinforcement exhibit about 30-40% higher strength as compared to the composites made with single reinforcement, either with fly ash as filler or with chopped fibers.

• 전기화학회지
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• 제5권3호
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• pp.106-110
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• 2002

Ethylene carbonate(EC), propylene carbonate(PC), dimethyl carbonate(DMC)의 가소제와 $LiPF_6$ 리튬염 및 $TiO_2$ 충진제를 이용하여 젤형 polyacrylonitrile(PAN) 전해질을 제조하였다. 고분자 전해질의 전기화학적 안정성, 이온전도도, 리튬전극과의 호환성 등의 전기화학적 특성과 기계적 특성을 조사하였다. 이러한 고분자 전해질을 이용하여 조립된 리튬이차전지의 충방전 특성을 조사하였다 EC, PC 혼합 가소제를 이용하여 제조된 고분자 전해질은 $TiO_2$가 첨가됨에 따라 고분자 전해질이 견딜 수 있는 최대 하중이 2배 가깝게 증가하였다. EC, PC혼합 가소제와 $TiO_2$가 혼합된 고분자 전해질은 상온에서 $2\times10^{-3}S/cm$의 이온전도도를 나타내었고, 4.5V까지 전기화학적으로 안정하였다. 리튬금속을 사용하여 제조된 셀의 임피던스 결과에서도 EC, PC 혼합 가소제와 $TiO_2$가 혼합된 고분자 전해질이 20일 동안 계면 저항 $130\Omega$으로 가장 안정하였다. $LiCoO_2$ 양극과 리튬 음극, $TiO_2$가 혼합된 고분자 전해질로 구성된 전지는 충방전효율이 1C 방전속도에서 $90\%$를 나타내었다.

• 한국전기전자재료학회논문지
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• 제22권11호
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• pp.935-940
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• 2009

In this research, the composites (100-x)LCP-xBNT (x = 0, 10, 20, 30, 40 vol.%) were fabricated with thermoplastic LCP(Liquid Crystal Polymer) and BNT($BaNd_2Ti_4O_{12}$) which is a high frequency dielectric material. Their dielectric properties, mechanical strength and microstructure were investigated by Impedance analyser, Instron and SEM. In order to fabricate LCP-BNT composites, LCP resin was put into the twin screw type mixer($310^{\circ}C$), melted by keeping for 10 min. After that, BNT filler was dispersed with melted LCP resin for 15 min. in the mixer. For measuring the dielectric properties and mechanical strength, Composite specimens were made by pressing composite granule (LCP-BNT) with 7 ton in the mold at $310^{\circ}C$. With increasing the BNT content (0~40 vol.%) of the composite, Its dielectric constant increased, dielectric loss and flexural strength decreased. The dielectric constant and flexural strength of composites with 20~30 vol.% of BNT filler are 4.1~6.0 and 35~55 MPa respectively. BNT/LCP composite is the potential substrate material for the high frequency application.