• Restorative Dentistry and Endodontics
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• 제22권2호
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• pp.792-800
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• 1997

The purpose of this study was to evaluate the adaptation of self-cured glass ionomer cement and resin-modified glass ionomer cement and polyacid-modified resin composite, which are light-cured giass ionomer cements, to dentin surface. Twelve extracted human maxillary and mandibular molar teeth were used in this study. The entire occlusal dentin surfaces of teeth were exposed with Diamond Wheel Saw and smoothed with sand papers (300, 600, 1200grits). They were randomly assigned into 3 groups according to glass ionomer cements used; Control group- Fuji II, Expeimental group 1 - Fuji II LC, Expeimental group 2 - Dyract. According to the manufacturer's directions, three glass ionomer cements were bonded to exposed dentin surfaces of the tooth crown and cured. Crowns and glass ionomers were trimmed after 24hrs and sectioned horizontally and vertically with diamond saw. The interface of glass ionomer cements and dentin was examined under SEM. The results were as follows : 1. Good adatation between glass ionomer cement and dentin on the horizontal section was showed in control and experimental group 1, but the gap of $20{\mu}m$, which was observed distinct separation between glass ionomer cement and dentin, was showed in experimental group 2. 2. Good adatation between glass ionomer cements and dentin on the vertical section was showed in control and experimental group 1, but the gap of 80-$100{\mu}m$ was showed in experimental group 2. 3. Cohesive fracture within glass ionomer cements in control and experimental group 1 was showed, but no cohesive fracture was showed in experimental group 2.

• 한국세라믹학회지
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• 제17권4호
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• pp.203-207
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• 1980

The optical absorption of high index glasses of the system TiO2-BaO-B2O3 prepared from the raw materials for an optical waveguide glass has been measured in the near ultraviolet region. The amount of Ti3+ in the glass could be reduced to a level less than 5 ppm by melting a batch added with pure nitric acid, using a fused quartz crucible in an oxygen gas atmosphere. The ultra-pure glass of 10mm thick prepared in such a way did not show any appreciable color even for the one containing 30 mol% TiO2 and having refractive index nD of 1.84 and Abbe's number vD of 28.8. The wavelength of ultraviolet absorptin edge was longer for the glass of higher index and higher dispersdion. The melting of a TiO2 containing glass in a platinum crucible resulted in a coloration of the glass due to the dissolved plutinum from the crucible, which was more intense for the one containing larger amount of TiO2.

• 한국전기전자재료학회논문지
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• 제27권11호
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• pp.712-717
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• 2014

Glass ceramic has a high mechanical strength and low sintering temperature. So, it can be used as a thick film substrate or a high strength insulator. A series of glass ceramic samples based on MgO-$Al_2O_3-SiO_2-ZrO_2$ (MASZ) were prepared by melting at $1,600^{\circ}C$, roll-quenching and heat treatment at various temperatures from $900^{\circ}C$ to $1,400^{\circ}C$. Dependent on the heat treatment temperature used, glass ceramics with different crystal phases were obtained. Their nucleation behavior, microstructure and mechanical properties were investigated with differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Vicker's hardness testing machine. With increasing the heat treatment temperature of MASZ samples, their hardness and toughness initially increase and then reach the maximum points at $1,300^{\circ}C$, and begin to decrease at above this temperature, which is likely to be due to the softening of glass ceramics. As the content of $ZrO_2$ in MAS glass ceramics increases from 7.0 wt.% to 13 wt.%, Vicker's hardness and fracture toughness increase from $853Kg/mm^2$ to $878Kg/mm^2$ and $1.6MPa{\cdot}m^{1/2}$ to $2.4MPa{\cdot}m^{1/2}$ respectively, which seems to be related with the nucleation of elongated phases like fiber.

• 한국광학회지
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• 제6권2호
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• pp.130-134
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• 1995

이득 선폭이 넓고 가공이 쉬원 고출력 제이저의 증폭 이득 매질로 유리한 Nd:glass 이득 매질의 소신호 이득 계수를 측정하고 이 Nd:glass를 이용하여 제작한 cavity-dumping형 레이저의 출력 특성을 조사하였다. 소신호 이득 계수를 측정하기 위해 Nd:glass, Pockels cell, 편광분할기 등을 포함하는 공진기를 구성하였으며, 측정된 소신호 이극 계수는 전기 입력 에너지가 100J일 때 $0.088 cm_{-1}$ 공진기의 왕복 내부 손실은 56%였다. Cavity-dumping형 레이저 공진기는 곡률반경이 2m인 두개의 전반사경과 Nd:glass, Pickels cell, 편광분할기, $\lambda/4$ plate 등으로 구성되었으며 제작된 레이저의 출력 에너지는 전기 입력 에너지가 140J일 때, 최대 0.85J이었고 출력 레이저 펄스폭은 8ns였다.

• 한국자기학회지
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• 제12권5호
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• pp.195-200
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• 2002

각종 산화물을 첨가하여 Co$_2$Z type Ba-ferrite의 저온소결에 관하여 연구하였다. Co$_2$Z type Ba-ferrite 상은 2회 하소과정을 통하여 얻을 수 있었으며, 생성된 상의 XRD peaks는 일부 minor peaks 제외하고는 standard peaks와 거의 일치하였다 제조된 분말은 저온소결을 위하여 ZnO-B$_2$O$_3$ glass리 단독 첨가 및 CuO 또는 Bi$_2$O$_3$와 복합 첨가하였으며, 또한 ZnO-Bi$_2$O$_3$ glass를 단독 첨가하였다. 소결은 900~100$0^{\circ}C$에서 수행하였다. ZnO-B$_2$O$_3$ glass의 단독 첨가 시, 첨가량이 7.5 wt%일 때 가장 높은 수축거동을 나타내었다. ZnO-Bi$_2$O$_3$ glass와 CuO 또는 Bi$_2$O$_3$를 복합 첨가하였을 때, glass를 단독 첨가하였을 경우보다 수축률이 급격히 증가되었다. 또한 ZnO-Bi$_2$O$_3$ glass를 단독 첨가한 시편의 수축률과 초기 투자율은 ZnO-B$_2$O$_3$ glass를 단독 첨가한 시편보다 높은 값을 나타내었다.

• 한국세라믹학회지
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• 제33권12호
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• pp.1353-1364
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• 1996

Recently semiconductor doped glasses have attracted attention as nonlinear optical materials because of their large third order nonlinear optical properties. The transparent and homogeneous CdS-doped SiO2 glass thin films were obtained by the dip=coating process of the sol-gel method. Thin films were consisted of glasses containing CdS microcrystallites which were formed by dissolved Cd2+ and S2- ions in a SiO2 matrix solutions. A subsequent thermal treatment of this samples led the formation of colloidal agglomerates and finally of microcrystallites. The size of CdS microcrystallites was about 4 to 15 nm after thermal treatments at various heating conditions. From the optical absorption spectra of the CdS-doped SiO2 glass films it was found that the absorption edge was blue-shifted compared with that of the bulk CdS crystal(~2, 4 eV) and that the amount of energy shift was inversely proportional to the crystal size. And the band gap energy increased with the decrease in crystallite size indicating that the quantum size effects occured.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.272-273
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• 2006

LTCC(low temperature co-fired ceramics)용 glass/ceramic 복합체를 제조하기 위해 4 종류의 borosilicate계 glass를 선정하고 filler로 $Al_2O_3$ ceramics를 filler 사용하여 30~50 vol% glass frit에 따른 소결 및 유전 특성에 대하여 조사하였다. Glass frit은 $SiO_2$와 $B_2O_3$ 함량비를 고정한 후 R(CaO, BaO, ZnO, $Bi_2O_3$)에 따라 유리 연화온도(Ts)와 함량이 소결에 미치는 영향 및 유전 특성 변화를 고찰한 결과, CaO-$B_2O_3-SiO_2$ glass의 경우 다량의 2 차상이 형성되었고, 이에 $900^{\circ}C$ 이하에서 완전 소결이 이루어지지 않았으며, BaO-$B_2O_3-SiO_2$ glass는 celsian($BaAl_2Si_2O_8$) 결정이 형성되면서 소결성의 저하를 갖고 왔으며, ZnO-$B_2O_3-SiO_2$ glass는 소결이 진행됨에 따라 주상이 $Al_2O_3$에서 gahnite($ZnAl_2O_4$) 결정이 형성되면서 품질계수가 크게 증가하였으며, $Bi_2O_3-B_2O_3-SiO_2$ glass는 45 vol%일 때 $900^{\circ}C$에서부터 일정한 선수축율 특성을 나타내었지만, 다량의 액상으로 인하여 유전 특성의 저하를 나타내었다.

• 한국세라믹학회지
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• 제46권3호
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• pp.271-274
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• 2009

Redox investigation of Sn and S ion was attempted in alkaline earth borosilicate glass melts with only 1 mol% $Na_2O$ by means of Square Wave Voltammetry (SWV). According to voltammograms, there was only one peak due to $Sn^{4+}/Sn^{2+}$ in melt doped with $SnO_2$. The calculated standard enthalpy and entropy of the reduction of $Sn^{4+}$ to $Sn^{2+}$ were 116kJ/mole and 62 J/mol K, respectively. The determined redox ratio, [$Sn^{2+}$] / [$Sn^{4+}$] in the temperature range of $1300{\sim}1600^{\circ}C$ was in $0.4{\sim}2.1$. On the contrary, in the voltammogram of melt doped with $BaSO_4$ there was no peak due to $S^{4+}/S^o$ but shoulder that might be attributed to the adsorption of sulfur at the electrode. The absence of the peak related with $S^{4+}/S^o$ was discussed from the view-point of the thermal decomposition behavior of $BaSO_4$ in the glass batch.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.291-294
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• 2000

The crystallization behavior and dc Conductivities of CuO-P$_2$O$_{5}$ -Nb$_2$O$_{5}$ -V$_2$O$_{5}$ glasses prepared by quenching on the copper plate were investigated. The conductivities of the glasses were range from 10$^{-5}$ s.$cm^{-1}$ / at room temperature, but the conductivities of the glass-ceramics were 10$^{-3}$ s.$cm^{-1}$ / increased by 10$^2$order. The crystalline product in the glass-ceramics was CuV$_2$O$_{6}$ . The linear relationship between in($\sigma$T) and T$^{-1}$ suggested that the electrical conduction in the present glass-ceramics would be due to a small polaron hopping mechanism.

• 대한전기학회논문지
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• 제43권7호
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• pp.1152-1157
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• 1994

The glasses were prpared in the system CuI-CuS12TS-CuS12TO-MoOS13T by rapid quenching technique. These glasses have high ionic conductivities at 2$0^{\circ}C$ in the range of 10S0-1T[S/m], and the conductivities increase with increasing CuI and CuS12TS content. The value of activation energy for dielectric relaxation is nearly identical with that for conductivity. The cole-Cole parameter $\beta$ for representation of the distribution of dielectric relaxation times varies the range from 0.92 to 0.96. This parameter has a weak dependence on the composition of glass, and is independent of temperature. The correlation factors P for the glasses shows from 1.1 to 1.7.