• Restorative Dentistry and Endodontics
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• 제26권5호
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• pp.387-392
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• 2001

When cavity floor is near the pulp, polymerization of light-activated restorations results in temperature increase. This temperature increase cause by both the exothermic reaction process and the energy absorbed during irradiation. Therefore instating base is required. Most frequently used insulating base is glass ionmer. The purpose of this study was to evaluate intrapulpal temperature changes of glass ionomer according to various curing intensity and curing time. Caries and restoration-free mandibular molars extracted within three months were prepared Class I cavity of 3$\times$6mm with high speed handpiece. 1mm depth of dentin was evaluated with micrometer in mesial and distal pulp horns. Pulp chambers were filled with 37.0$\pm$0.1$^{\circ}C$ water to CEJ. Chromium-alumina thermocouple was placed in pulp horn for evaluating of temperature changes. glass ionomer material was placed in 2mm. total curing time was 40s: continuous 40s, intermittent 20s, intermittent 10s. Glass ionomer material was cured with 300mW/$\textrm{cm}^2$, 550mW/$\textrm{cm}^2$ light curing unit. The results were as follows : 1. Temperature in pulp increased as curing unit power is increased. 2. Temperature in pulp more increased continuous emission than intermittent emission.

• 한국세라믹학회지
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• 제31권8호
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• pp.861-868
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• 1994

CaO-Al2O3 glass is a good candidate as optical fiber amplifier and laser. In this study, optical properties for 4I13/2longrightarrow4I15/2 transition of Er3+ ions doped in CaO-Al2O3 glasses were investigated. Optical absorptions, radiative transition probabilities and lifetimes for 4I13/2 level were evaluated by using Judd-Ofelt theory. Also, induced- emmision cross-sections of 4I13/2longrightarrow4I15/2 transition were calculated. Radiative transition probability and lifetime of 4I13/2 level were 144.6s-1, 690$mutextrm{s}$ respectively for 60CaO.40Al2O3 glass(FS0) and 152.6s-1, 660 $mutextrm{s}$ for 54 CaO.36Al2O3.10SiO2 glass (FS10). Each induced-emission cross sections for FS0 and FS10 was 0.749$\times$10-20 $\textrm{cm}^2$, 0.892$\times$10-20 $\textrm{cm}^2$. Obtained values were comparable with those of ZBLA glass studied as optical fiber amplifier and laser material.

• 한국세라믹학회지
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• 제52권2호
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• pp.146-149
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• 2015

Silicate glasses with different $Nd_2O_3$ concentrations were prepared through conventional melt-quenching methods while PbS quantum dots (QDs) were precipitated through heat treatment. The peak wavelengths of absorption and the photoluminescence of PbS QDs shifted to the short-wavelength side as the concentration of $Nd_2O_3$ increased. The electron energy loss spectroscopy (EELS) indicated that $Nd^{3+}$ ions were preferentially distributed inside the PbS QDs instead of the glass matrix. In addition, there was no significant change in the lifetimes of the $Nd^{3+}:^4F_{3/2}$ fluorescence between the as-prepared glass ($607{\mu}s$) and the heat-treated glass($576{\mu}s$). $Nd^{3+}$ ions were surrounded by oxygen instead of sulfur and the Nd-O clusters probably acted as nucleating centers for the formation of PbS QDs inside the glasses.

• Korean Chemical Engineering Research
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• 제44권5호
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• pp.513-519
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• 2006

본 연구에서는 유리(glass)와 석영(quartz)을 재질로 사용하여 MEMS(micro-electro mechanical systems) 공정을 통해 전기영동(electrophoresis)을 위한 microchip을 제작하였다. UV 광이 실리콘(silicon)을 투과하지 못하는 점에 착안하여, 다결정 실리콘(polycrystalline Si, poly-Si) 층을 채널 이외의 부분에 증착시킨 광 차단판(optical slit)에 의해 채널에만 집중된 UV 광의 신호/잡음비(signal-to-noise ratio: S/N ratio)를 크게 향상시켰다. Glass chip에서는 증착된 poly-Si 층이 식각 마스크(etch mask)의 역할을 하는 동시에 접합표면을 적절히 형성하여 양극 접합(anodic bonding)을 가능케 하 였다. Quartz 웨이퍼에 비해 불순물을 많이 포함하는 glass 웨이퍼에서는 표면이 거친 채널 내부를 형성하게 되어 시료용액의 미세한 흐름에 영향을 미치게 된다. 이에 따라, HF와 $NH_4F$ 용액에 의한 혼합 식각액(etchant)을 도입하여 표면 거칠기를 감소시켰다. 두 종류의 재질로 제작된 채널의 형태와 크기를 관찰하였고, microchip electrophoresis에 적용한 결과, quartz과 glass chip의 전기삼투 흐름속도(electroosmotic flow velocity)가 0.5와 0.36 mm/s로 측정되었다. Poly-Si 층에 의한 광 차단판의 존재에 의해, peak의 S/N ratio는 quartz chip이 약 2배 수준, glass chip이 약 3배 수준으로 향상되었고, UV 최대흡광 감도는 각각 약 1.6배 및 1.7배 정도 증가하였다.

• 생태와환경
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• 제47권spc호
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• pp.31-38
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• 2014

2008년부터 2012년까지 임진강 하구역에서 어류 군집과 실뱀장어 소상을 조사한 결과 다음과 같다. 채집된 어류는 총 18과 42종이었으며 이 중 한국고유종은(Microphysogobio jeoni) 1종으로 고유화빈도가 0.04%이었다. 국외에서 도입된 외래어종은 떡붕어(Carassius cuvieri)와 초어(Ctenophayngodon idellus) 2종이 출현하였고 개체수 비교풍부도는 0.06%로 매우 낮았다. 출현한 어종 중 순수담수어에 속하는 종은 17종(40.5%), 회유성 6종 (14.2%), 기수성 8종 (19.1%), 해산어 11종(26.1%) 등 이었다. 개체수 구성비가 높은 종은 뱀장어(Anguilla japonica (glass eels, 49.8%)), 웅어 (Coilia ectens, 23.3%), 두우쟁이 (Saurogobio dabryi, 8.1%), 강주걱양태(Repomucenus olidus, 3.3%), 점농어(Lateolabrax maculata, 2.9%), 가숭어(Chelon haematocheilus, 2.8%)등 이었으며 생체량에 있어서는 C. ectens (33.6%), C. haematocheilus (14.2%), 잉어(Cyprinus carpio, 10.5%), 숭어(Mugil cephalus, 9.1%), S. dabryi (7.6%) 등이 풍부하였다. 우점종은 개체수에 있어 A. japonica (glass eels)이었고 C. ectens가 아우점종이었다. 파주시에서 연간 어획된 양은 83.6~240.3 t이었으며 2011년과 2012년에 급격히 감소하였다. 어획된 어류 중 생체량에 있어 M. cephalus (48.0~80.0%), C. carpio (6.7%), 붕어(Carassius auratus, 4.9%), 메기 (Silurus asotus, 3.9%), 황복(Takifugu obscurus, 2.5%), A. japonica (adult, 2.2%), 동자개(Pseudobagrus fulvidraco, 2.1%) 등의 순으로 풍부하였다. 연간 포획된 A. japonica (glass eels)는 양은 0.03~1.13 t이었고 연평균 212.0 kg이었으며 개체당 평균 체중이 0.16 g으로 약 1,325,000개체이었다.

• 마이크로전자및패키징학회지
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• 제3권2호
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• pp.27-38
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• 1996

Lithium fluorhectorite 결정상을 함유한 glass ceramics 분말의 형성과 제조된 glass ceramics 분말을 이용한 저온 소결기판의 특성평가를 하였다. Li2O-MgO-MgF2-SiO2 계 유 리로 핵형성 및 결정 성장을 실시하여 lithium fluorhectorite 결정상을 지닌 glass ceramics 를 제조하였다. 유리시편의 핵형성 온도는 46$0^{\circ}C$였고 결정성장온도는 600, 640, 110$0^{\circ}C$에서 나타났다. $600^{\circ}C$에서의 결정상으 Li2.4LiSi4O10F2가 나타났다. Li2.4Mg8LiSi4와 Li2.8Mg0.6SiO4은 lithium fluorhectorite 결정상으로 되기 위한 중간상임을 확인할수 있었다. 64$0^{\circ}C$에서 열처리 후 110$0^{\circ}C$에서 재열처리하여 형성된 결정은 lithium fluorhectorite 와 tridymite가 최종 결정 상으로 나타났다. 이것은 수중에서 water swelling 현상에 의하여 분말화할 수 있었다, 기판 제조용 slurry를 제조하기 위해 glass ceramics 분말에 Al2O3분말을 0,25,50wt%로 혼합한것 과 glass ceramics 분말에 potashborosilica-te glass 분말을 15, 30, 45, 60 wt% 로 배합하 여 doctor blade 법으로 green sheet를 제조하였다. green sheet 는 950~150$0^{\circ}C$로소성하여 기판의 특성을 평가하였다. 겉보기 기공율은 3.06~19,14%이었고, 전기적 특성으로 유전상수 는 3~5(100KHz)를 나타내었다.

• 한국세라믹학회지
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• 제32권3호
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• pp.385-393
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• 1995

Akali-resistant porous glass was prepared by phase separation in Na2O-B2O3-SiO2 system containing ZrO2 and MgO. ZrO2 was added for alkali-resistance and MgO for anti-cracking during leaching. Optimal content of ZrO2 for alkali-resistance was 7wt% and devitrification by heat treatment resulted from further addition. Pore size and pore volume were decreased and specific surface area was increased with ZrO2 addition due to depression in phase separation. Addition of 3mol% MgO to mother glass containing 7wt% ZrO2 was effective for anti-crack during leaching. In this case, with phase separation at 55$0^{\circ}C$ and 5$25^{\circ}C$ for 20 hrs. crack-free porous glasses could be prepared. The relation between pore size r and heat treatment time t at 55$0^{\circ}C$ was D=25.58＋18.16t. According to measurement of gas permeability, the mechanism of gas permeation was Knudsen flow. N2 and He permeability of porous glass which was prepared by heat treatment at 55$0^{\circ}C$ for 20 hrs. were 0.843$\times$10-7mol/$m^2$.s.Pa and 2.161$\times$10-7mol/$m^2$.s.Pa respectively.

• 대한치과기공학회지
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• 제14권1호
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• pp.95-118
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• 1992

Glass ceramics for crown were prepared by adding 3$\sim$11 wt% TiO2 to the weight percent composition of 34.7 CaO, 27.8 SiO2, 18.3P2O5, 12.6MgO and 6.6 TiO2. The starting glasses were prepared by melting the powdered batch in alumina crucible at 1350$\sim$1400 for 1 hr and then quenching into a distilled water. The nucleation and crystallization of the crystalline glass ceramics for crown were studied by DTA, SME and X-ray diffraction analysis. Frit containing 9.11 wt% TiO2 had crystallization temperature of 850$\sim$1075 and major crystalline phase was identified by X-ray diffraction as diopside(CaO-MgO-2SiO2). Activation energies for the crystallization processes were obtained from DTA by varing rates for the fits, and were calculated from modified Ozawa and Kissinger equations. Activation energy for the crystallization processes of the S-4 frit was 489.6 KJ/mol.

• 한국세라믹학회지
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• 제52권2호
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• pp.103-107
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• 2015

The effective glass frit composition used to absorb laser energy and to seal commercial dye-sensitized solar cell panel substrates has been previously developed using $V_2O_5-TeO_2$-based glass with 10 wt% ${\beta}$-eucryptite as a CTE controlling filler. The optimum sealing conditions are provided using a 3 mm beam, a laser power of 40 watt, a scan speed of 300 mm/s, and 200 irradiation cycles. In this study, the feasibility of the developed glass frit is investigated in terms of the sealing strength and chemical durability against the commercial iodide/triiodide electrolyte solution and fluorine-doped tin oxide (FTO) electrode in order to increase the solar cell lifetime. The sealing strength of the laser-sealed $V_2O_5-TeO_2$-based glass frit is $20.5{\pm}1.7MPa$, which is higher than those of thermally sealed glass frit and other reported glass frit. Furthermore, the developed glass frit is chemically stable against electrolyte solutions. The glass frit constituents are not leached out from the glass after soaking in the electrolyte solution for up to three months. During the laser sealing, the glass frit does not react with the FTO electrode; thus, the resistivity of the FTO electrode beneath the laser-sealed area remains the same.

• 조명전기설비학회논문지
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• 제29권12호
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• pp.28-32
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• 2015

In this work, we reported fabrication of sealing the glass substrate using laser treatment at low temperature for electrochemical luminescence (ECL) cell. The laser treatment at temperature is using laser diode. The glass substrate sealing by laser treatment tested at 3-10W, 2-5 mm/s for build and tested. The sealing laser treatment method will allow associate coordination between the two glass substrate was enclosed. The effect of laser treatment to sealing the glass substrate was found to have cracks and air gap at best thickness of about 550-600 im for condition 3 W, 3 mm/s. The surface of sealing was roughness which was not influent to electrodes It can reduce the cracks, crevices and air gaps as well, improves the performance viscosity in butter bus bar electrodes. Therefore, it is more effective viscosity between two FTO glasses substrate.