• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.165-165
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• 2000

Glass slides were chemically etched with sulfuric acid using five different methods. we investigated the effects of the chemical etching conditions on such properties as chemical composition, surface roughness, and the thermal stability of the glass. Sodium and carbon atoms in the surface of the glass are effectively eliminated by chemical etching with sulfuric acid. The glass slides were boiled for 30 min in 95% sulfuric acid and were depth profiled at room temperature with X-ray photoelectron spectroscopy (XPS), the Na ls signal was not detected in the detection limit of XPS. Surface morphology of the glass was very different depending on the concentration of sulfuric acid. The surface of the glass etched with 50% sulfuric acid was rougher than that of glass etched with 95% sulfuric acid. The sodium concentration of the glass boiled for 30 min in 95% sulfuric acid was nearly zero at the glass surface, and the sodium composition changed very little with annealing temperatures up to 35$0^{\circ}C$ in a vacuum environment. However the sulfur concentration at the glass surface due to the sulfuric acid increased with increasing temperature.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.42.2-42.2
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• 2011

$TiO_2$ films were modified by adding a glass frit as a light scattering particle and applied to an anode electrode in dye-sensitized solar cells (DSSCs) to enhance the adhesion between $TiO_2$ and fluorine doped transparent oxide (FTO). Low melting point glass frits at contents of (3 to 7wt%) were added to the nano crystalline $TiO_2$ films. The light scattering properties, photovoltaic properties and microstructures of the photo electrodes were examined to determine the role of the low glass transition temperature ($T_g$) glass frit. Electrochemical impedance spectroscopy, Brunauer-Emmett-Teller method and scratch test were conducted to support the results. The DSSC with the $TiO_2$ film containing 3wt% low Tg glass frit showed optimal performance (5.1%, energy conversion efficiency) compared to the $TiO_2$-based one. The photocurrent density slightly decreased by adding 3wt% of the frit due to its large size and non conductivity. However, the decrease of current density followed by the decrease of electron transfer due to the large frit in $TiO_2$ electrode was compensated by the scattering effect, high surface area and reduced the electron transfer impedance at the electrolyte-dye-$TiO_2$ interface. The stability of the photo electrodes was improved by the frit, which chemically promoted the sintering of $TiO_2$ at relatively low temperature ($450^{\circ}C$).

• Structural Engineering and Mechanics
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• 제49권5호
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• pp.555-568
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• 2014

In this article, stability of composite conical shells subjected to dynamic external pressure is investigated by numerical and experimental methods. In experimental tests, cross-ply glass woven fabrics were selected for manufacturing of specimens. Hand-layup method was employed for fabricating the glass-epoxy composite shells. A test-setup that includes pressure vessel and data acquisition system was designed. Also, numerical analyses are performed. In these analyses, effect of actual geometrical imperfections of experimental specimens on the numerical results is investigated. For introducing the imperfections to the numerical models, linear eigen-value buckling analyses were employed. The buckling modes are multiplied by very small numbers that are derived from measurement of actual specimens. Finally, results are compared together while a good agreement between results of imperfect numerical analyses and experimental tests is observed.

• Bulletin of the Korean Chemical Society
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• 제29권1호
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• pp.181-186
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• 2008

2,5-Di-(2'-hydroxyethoxy)-4'-nitrostilbene (3) was prepared and polycondensed with terephthaloyl chloride, adipoyl chloride, and sebacoyl chloride to yield novel T-type polyesters (4-6) containing the NLO-chromophores dioxynitrostilbenyl groups, which constituted parts of the polymer backbones. Polymers 4-6 are soluble in common organic solvents such as acetone and N,N-dimethylformamide. They showed thermal stability up to 260 oC in thermogravimetric analysis with glass-transition temperatures obtained from differential scanning calorimetry in the range 90-95 oC. The second harmonic generation (SHG) coefficients (d33) of poled polymer films at the 1064 nm fundamental wavelength were around 1.42 ´ 10-9 esu. The dipole alignment exhibited high thermal stability up to 5 oC higher than glass-transition temperature (Tg), and there was no SHG decay below 100 oC due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

• 열처리공학회지
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• 제14권6호
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• pp.345-349
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• 2001

This study has investigated the effect of thermal stability and mechanical property of $Fe_{80-X}P_{10}C_6B_4M_X$(X=2, 4, 6, M=transition metal) amorphous alloys fabricated by the melt-spun process. The glass transition temperature($T_g$), crystallization temperature($T_x$) and hardness increase with decreasing electron concentration (e/a) from about 7.38 to 7.18. The decrease of e/a implies the increase in the attractive bonding state between the M elements and other constituent element. The decrease in a/e leads to the enhancement of the attractive bonding state among the constituent elements which is favorable for the increase in $T_g$, $T_x$ and hardness.

• Journal of Pharmaceutical Investigation
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• 제16권1호
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• pp.8-11
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• 1986

There have been many difficulties in utilization of polyethylene (PE) container for volatile ingredients because of its high permeability. We selected glycol-modified polyethylene terephthalate (PETG) lately being used and evaluated the stability of 0.5% chlorobutanol solution for PETG. We used PE bottle, glass flask and rubber stoppered vial for comparison and assayed chlorobutanol contents of the samples stored at various temperatures for nine weeks by HPLC method. The results indicated that the stability of chlorobutanol in PETG container was almost similar to that in glass flask, and was superior to that in PE bottle and rubber stoppered vial.

• Journal of Information Display
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• 제5권3호
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• pp.25-29
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• 2004

Effects of additing various types of ceramic fillers to the BZB-based glass on the thermo-chemical stability, optical reflectance, and mechanical properties were investigated. The glass system demonstrated the feasibility to host various types of ceramic fillers to form micro-composites at the processing temperature suitable for PDP systems. The optical reflectance and mechanical strength of the filler-glass composites were improved as compared to the glass itself. These results demonstrate the feasibility of applying the Pb-free BZB-based glass system as a matrix for employing various types of crystalline ceramic fillers to be used as barrier rib materials in plasma display panels.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 추계학술대회
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• pp.96-98
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• 2004

At the previous papers, we showed that K2O-CaO-P2O5 glasses had a solubility in air so that they could be used for glass fertilizer. In this work, we fabricated the Eco-glass fertilizer containing trace elements such as B, Mg, Zn, Fe, Cu, Co, and Mo by a melt-quenching process and the dissolution properties of these glasses were investigated with pH meter and ICP analyzer. In case of the glasses containing the trace elements, effect of trace elements on the dissolutions is not obvious and ignorant the stability of mother glass. Also, the dissolution amounts of each trace elements depend on the mother glass composition and the quantity of each trace element, and mother glasses determined the dissolving velocity of chemical elements.

• 한국추진공학회지
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• 제19권1호
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• pp.1-8
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• 2015

MEMS 추력기를 위한 유리 박막 마이크로 점화기를 개발하였다. 수십 마이크로 미터의 두께를 가지는 유리 박막을 사용하여 점화기의 구조적 안정성을 향상시켰다. 마이크로 점화기는 박막 형성을 위한 감광 유리의 이방성 식각과 점화 코일 형성을 위한 Pt/Ti 증착 공정으로 제작되었다. 개발된 점화기는 유리 박막의 구조적 안정성으로 인하여 특별한 장치없이 추진제 충전이 가능하였다. 점화 실험이 성공적으로 이뤄졌으며 최소 점화 지연은 27.5 ms, 최소 점화 에너지는 19.3 mJ 이였다.

• 대한소아치과학회지
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• 제49권4호
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• pp.428-441
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• 2022

이 연구의 목적은 알카자이트 수복재와 소아치과 영역에서 널리 사용되고 있는 수복재들의 색 안정성을 비교하고, 다양한 음료에서의 색상 변화를 비교하는 것이다. 글라스아이오노머, 레진강화형 글라스아이오노머, 알카자이트 수복재, 복합레진의 시편을 준비하였고, 열순환 후 색 안정성을 측정하였다. 침전 전과 7일, 14일, 21일, 28일 후 CIE L^*a^*b^*값의 색상 변화를 분석하기 위해 각 수복재료의 시편을 5개의 군으로 나누어 각각 PBS, 커피, 녹차, 콜라, 오렌지주스 용액에 침전시켰다. 열순환 후 복합레진에서 가장 높은 색 안정성을 보였고, 알카자이트 수복재, 글라스아이오노머, 레진강화형 글라스아이오노머 순으로 높은 안정성을 보였다. 7일간 다양한 용액에 침전시킨 결과 모든 시편에서 색상 변화가 나타났으며, 알카자이트 수복재는 글라스아이오노머 계열보다 낮은 색상 변화를 보였고, 복합레진보다는 높은 색상 변화를 나타냈다. 알카자이트 수복재는 커피에서 가장 많은 색상 변화가 나타났으며 그 다음은 녹차, 오렌지주스 순이었으나, 콜라와 PBS 용액에서는 침전 28일 이후에도 색상 변화를 거의 보이지 않았다.