• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.3
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• pp.315-324
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• 1994

The effects of impurities of the quartz raw materials on the trasformation of quartz to cristobalite were investigated. As the increase of impurities content, the amount of cristobalite crystal increased, whereas the fusion temperature of quartz and the formation temperature of cristobalite decreased. And the courses of the transformation of quartz to cristobalite were examined. The course of quartz $\rightarrow$ transitional noncrystalline phase $\rightarrow$ melt (T) and quartz $\rightarrow$ transitional noncrystalline phase $\rightarrow$ cristobalite $\rightarrow$ melt (C) were always coexisted on the transformation of quartz. In the case of high purity quartz raw material, the T course was predominant, while in low purity quartz raw material, the C course was predominant. And the calculated density of heat treated sand by the quantitative analysis of quartz and cristobalite phase by XRD is well agreed with the measured density by pycnometer. On the melting proces of quartz glass, the volume expansion of sand at a certain temperature can be estimated with the calculated density data.

• Korean Journal of Optics and Photonics
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• v.5 no.4
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• pp.499-504
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• 1994

Ti-doped BSG (borosilicate glass) soot films on the silicone substrate have been deposited in the mixture of $SiCl_{4}$, TMB, $TiCL_{4}$ by flame hydrolysis deposition technique. The soot films are melted to form integrated fine glass films. We can fabricate thick films of serveral $10{\mu}m$ with deposition rate,more than $0.5{\mu}m$/min. Refractive index difference of BSG films are increased to more than 0.3% as function of the amount of Ti dopant. As a result of the process an optical waveguide which is simmilar with dimmension and refractive difference of optical fiber is produced. $BCl_{3}$ is widely used for B dopant, but we abtained the good results by the use of TMB in place of $BCl_{3}$. The melting point of silica soot glass is reduced to $1200^{\circ}C$ increasing B dopant. From FTIR analysis $B_2O_3$ content up to about lOmol% in BSG films. films.

• Korean Journal of Materials Research
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• v.26 no.1
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• pp.22-28
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• 2016

In this study, we fabricated high quality color conversion component with green/red phosphor and low melting glass frit. The color conversion component was prepared by placing the green and red phosphor layer on slide glass via screen printing process. The properties of color conversion component could be controlled by changing coating sequence, layer thickness and heat treatment temperature. We discovered that optical properties of color conversion component were generally determined by the lowest layer. On the other hand, the heat treatment temperature also affected to correlated color temperature (CCT) and color rending index (CRI). The color conversion component with a green (lower) - red (upper) layer which was sintered at $550^{\circ}C$ showed the best optical properties: CCT, CRI and luminance efficacy were 3340 K, 78, and 56.5 lm/w, respectively.

• Journal of Periodontal and Implant Science
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• v.38 no.sup2
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• pp.273-298
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• 2008

Purpose: The aim of this review is to introduce a novel bone-graft material for hard-tissue regeneration based on the calcium phosphate glass(CPG). Materials and Methods: CPG was synthesized by melting and subsequent quenching process in the system of CaO-$CaF_2-P_2O_5$-MgO-ZnO having a much lower Ca/P ratio than that of conventional calcium phosphates such as HA or TCP. The biodegradability and bioactivity were performed. Effects on the proliferation, calcification and mineralization of osteoblast-like cells were examined in vitro. Influence in new bone and cementum formations was investigated in vivo using calvarial defects of Sprague-Dawley rats as well as 1-wall intrabony defect of beagle dogs. The application to the tissue-engineered macroporous scaffold and in vitro and in vivo tests was explored. Results: The extent of dissolution decreased with increasing Ca/P ratio. Exposure to either simulated body fluid or fetal bovine serum caused precipitation on the surface. The calcification and mineralization of osteoblast-like cells were enhanced by CPG. CPG promoted new bone and cementum formation in the calvarial defect of Sprague-Dawley rats after 8 weeks. The macroporous scaffolds can be fabricated with $500{\sim}800{\mu}m$ of pore size and a three-dimensionally interconnected open pore system. The stem cells were seeded continuously proliferated in CPG scaffold. Extracellular matrix and the osteocalcin were observed at the $2^{nd}$ days and $4^{th}$ week. A significant difference in new bone and cementum formations was observed in vivo (p<0.05). Conclusion: The novel calcium phosphate glass may play an integral role as potential biomaterial for regeneration of new bone and cementum.

• Korean Journal of Materials Research
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• v.24 no.1
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• pp.48-52
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• 2014

The Mg-enriched magnesium aluminum silicate (MAS) glass is known for its higher mechanical strength and chemical resistance. Among such glasses, cordierite ($Mg_2Al_4Si_5O_{18}$) is well known to have a low thermal expansion and low melting point. Polycrystalline engineering ceramics such as alumina can be strengthened by a surface modification with low thermal expansion materials. The present study involves the synthesis of cordierite by a sol-gel process and investigates the effect of glass penetration on the surface of alumina. The cordierite powders were prepared from $Al(OC_3H_7)_3$, $Mg(OC_2H_5)_2$ and tetraethyl orthosilicate by hydrolysis and condensation reaction. The cordierite powders were characterized by X-ray diffraction (XRD, Rigaku), scanning electron microscope (SEM, JEOL: JSM-5610), energy dispersive spectroscopy (EDS, JEOL: JSM-5610), and universal testing machine (UTM, INSTRON). The X-ray diffraction patterns showed that the synthesized particles were ${\mu}$-cordierite calcined at $1100^{\circ}C$ for 1 h. The shape of synthesized cordierite was changed from ${\mu}$-cordierite to ${\alpha}$-cordierite with increasing calcination temperature. Synthesized cordierite was used for surface modification of alumina. Cordierite powders penetrated deeply into the alumina sample along grain boundaries with increasing temperature. The results of surface modification tests showed that the strength of the prepared alumina sample increased after surface modification. The strength of a surface modified with synthesized cordierite increased the most, to about 134.6MPa.

• Composites Research
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• v.34 no.1
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• pp.1-7
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• 2021

Fiber-reinforced thermoplastic composites are applied to transport industries to lightweight of body, and applications will be expanded gradually. In this study, the impregnation and mechanical properties of continuous glass fiber (GF) reinforced polycarbonate (PC) composites were evaluated with different molecular weights of PC. The continuous GF reinforced PC composite were prepared by using GF fabric and PC film via continuous compression molding method. The melting flow index and tensile strength of PC matrix were evaluated with different molecular weights. Mechanical properties (tensile, flexural, and compressive) and pore rate of GF/PC composite were evaluated with different molecular weights of PC. The fracture behavior was analyzed to fracture surface of GF/PC composite using FE-SEM images. As these results, it was condition of representing the best mechanical property that the GF/PC composite was prepared by using PC of 20,000 g/mol as matrix.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.2
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• pp.99-105
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• 2010

This paper investigated the characteristics of wasteform containing a spent zeolite used as a separating agent of FPs for recycling LiCl waste which would be generated from pyrochemical process of spent PWR fuel. In this study, a conventional borosilicate and Ca-rich glass were used as a consolidating agent for spent zeolite and it's mixing ratio was changed in the range, $25{\sim}35wt%$. The leach rates of Cs and Sr had about $0.1{\sim}0.01g/m^2day$ and $0.001{\sim}0.0001g/m^2day$, respectively. The leach resistance of Cs increased with amount of SAP and it showed about 10 times higher in the Ca-rich glass wasteform than in the conventional borosilciate glass wasteform. The compressive strength of wasteform was affected with the amount of glass. Thermal expansion rate of containing 30wt% glass has relatively lower than others. Also, the melting temperature was little changed in given mixing ratio of glass.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2901-2906
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• 2007

A solver for icing and condensation of water has been developed. The phase change process was solved by the enthalpy method. For the code validation, the temperature and the phase change from water to ice of the driven cavity were calculated. Also, the melting process of the frost on the windshield glass of an automobile has been simulated. The calculation showed a good agreement with analytical solution and other numerical results. Using the present validated code, the condensation of water vapor has been first tried. The computed results provided some physical features of condensation phenomena even though experimental data and other numerical data were not available. For future work, it is recommended to throughly investigate the effects of boundary conditions on the solution.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.24-26
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• 1999

본 논문에서는 용해로 이상감시를 위한 실시간 유리 용해로 운전 전문가시스템을 구축한 결과를 소개한다. 유리 용해 공정에서는 운전자의 경험지식에 의해 내부의 상황을 판단하게 되고, 이는 용해로 수명과 제품의 품질에 중요한 영향을 준다. 이를 전문가 시스템으로 구현하기 위하여, 먼저, 기존 운전자의 지식을 취합, 분석한다. 그 후, 취합된 각 지식들의 특성에 부합하도록 이진 룰(Crisp Rule)과 퍼지 룰(Fuzzy Rule)로 구분한다. 이 때, 선형 회귀분석을 통하여 퍼지 룰의 입력을 결정함으로써 보다 정확한 운전 지식의 표현이 가능하도록 하였다. 설계된 알고리즘은 젠심 (Gensym)사의 실시간 전문가 시스템 개발 툴인 G2를 사용하여 구현하였다. 제시된 퍼지 전문가 시스템은 삼성코닝(주) 수원사어장의 실제생산 용해 공정에 직접 적용하여 그 효율성이 검증되었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.181-181
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• 2009

전자부품용 Pb-free sealing frit의 열팽창계수를 기판에 matching 시키기 위하여 음의 열팽창계수를 가지고 있는 $\beta$-Eucryptite, $\beta$-Spodumene를 합성하여 filler로 첨가하였다. 합성된 filler는 저온소성용 유리프리트의 높은 열팽창계수를 조절하기 용이하고, 유리프리트와 복합화 하여 소성하면 낮은 열팽창계수로 인한 우수한 열충격 저항성을 갖는다. Filler로써 $\beta$-Eucryptite, $\beta$-Spodumene의 결정성을 향상시키기 위해 $1250^{\circ}C$에서 5 시간 동안 유지하는 합성공정을 3회 반복 진행한 후 XRD를 사용하여 결정성을 분석하였고, TMA를 이용하여 filler 첨가량에 따른 유리프리트의 열팽장계수의 변화를 측정하였다. 또한, filler 입도와 함량에 따른 melting 특성을 분석하기 위해 Pill test를 진행하였으며, soda-lime glass 기판과의 접합면을 SEM을 사용하여 관찰하였다.