• 한국수산과학회지
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• 제1권2호
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• pp.135-137
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• 1968

1938년 A. F. Spillaus에 의하여 Bathythermograph가 고안된 이내 현재까지 수차 개량된 것이 제작판매하게 되어 해양조사 또는 어장탐색에 총중한 측기로 세계 각국에서 널리 보급되었다. 이 측기는 항해중이라도 수심 270m까지 내렸다 올림으로써 수심에 대한 수온이 동시에 연속된 일선으로 도은 또는 Smoked한 유리 판상에 기록되어 신속하게 수온의 미세한 수직분포를 알 수 있어 어장탐사에 필요한 나층의 판별과 그 수탐 및 수온의 판단에 큰 도움을 준다. 여기에서는 1, 2연전 이내 수산진흥원 산하 각 해구 시험소 및 교육기관을 비롯한 해양조사 관계기관에 다수양이 공급되어 널리 사용되고 있는 B.T의 Smoked-glass slide가 없어 사용의 곤란성 및 일본 또는 미국으로부터의 수입의 귀찮은 수속을 해소시키기 위하여 본원에서 실험 제작사용한 결과로서 간단하게 B.T Smoked glass Slide를 제작할 수 있는 방법을 소개하고자 한다.

• Carbon letters
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• 제1권2호
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• pp.82-86
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• 2000

The present research was undertaken to evaluate the possibility of water purification filter with activated carbon fibers (ACFs) using a very low cost precursor consisting of phenolic resin coated on glass fibers. The simplified procedure involving coating, curing and activation and a very low cost glass fiber as a raw material were adopted in order to reduce manufacturing cost. The breakthrough curves of the manufactured ACFs and the commercial activated carbon (AC, Calgon F-200) were investigated in the initial concentration range from 19 to 49 ppm for benzene, toluene and ethylbenzene. From breakthrough profiles, the manufactured ACFs had significantly faster adsorption kinetics than the AC. Especially the benzene breakthrough curves, the manufactured ACF (13 g of ACF with 32% of carbon on the glass) was over the limited level (5 ppb) after flowing of 32 l at initial concentration of 15 ppm, while the commercial AC was shown about 3 ppm in initial adsorption.

• 한국세라믹학회지
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• 제33권8호
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• pp.855-862
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• 1996

The nucleation and the crystal growth rates of Ge-Se-Te chalcogenide glass by two step heat-treatment and its effect on the mechanical optical properties and water-resistance were determined. The maximum nuclea-tion and crystal growth rate were 2.1$\times$103/mm3 .min at 28$0^{\circ}C$ and 0.4${\mu}{\textrm}{m}$/min at 33$0^{\circ}C$ respectively. When the crystal volume fraction with crystal size $1.5mutextrm{m}$ was about 4% the (hardness and fracture toughness were about 117kg/mm2 and 6.0 MPa.mm1/2)respectively. The weight loss of crystallized glass in water was lower than parent glass($25^{\circ}C$ for 32 hrs : 0.03% 8$0^{\circ}C$ for 16 hrs : 0.1%) as 0.01% at $25^{\circ}C$, 0.03% at 8$0^{\circ}C$ for 16 hrs : 0.1%) at $25^{\circ}C$ 0.03% at 8$0^{\circ}C$ respectively. The IR-transmittance decreased with increasing crystal size and crystal volume fraction. The IR-transmittance of crystallized glass with the crystal size of $1.5mutextrm{m}$ (crystal volume fraction : 4%) presented 56% which was about 4% lower than that of parent glass.

• Elastomers and Composites
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• 제55권4호
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• pp.277-280
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• 2020

In this study, mesoporous hollow silica spheres were synthesized using a polystyrene core and cetyltriammonium chloride (CTACl) as a pore template, and a low-cost water glass instead of expensive tetraethyl orthosilicate (TEOS) as a precursor. In addition, the material was synthesized by varying the concentration of polystyrene. Later, the polystyrene core and CTACl were removed by firing in a high-temperature heat-treatment process. The synthesized product was analyzed by various methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD), and N2-sorption analysis. It was confirmed that the hollow silica sphere had a hexagonal structure with a Brunauer-Emmett-Teller (BET) specific area of 1623 ㎡/g.

• 한국결정성장학회지
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• 제22권3호
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• pp.152-157
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• 2012

본 연구는 알칼리 활성화제로 NaOH와 물유리를 사용하고 리젝트애쉬와 고로슬래그를 혼합하여 지오폴리머를 제조하였다. 리젝트애쉬와 고로슬래그의 치환율과 물유리와 NaOH의 농도에 따른 압축강도를 측정하였다. 압축강도 측정결과로는 알칼리 활성화제로 NaOH 1 wt%, 물유리 3 wt%와 전량 고로슬래그를 사용한 경우 재령 28일차 강도가 38.91 MPa의 성능을 나타내었다. 압축강도 증진의 중요한 요인은 알칼리 활성화제의 비율과 리젝트애쉬와 고로슬래그의 치환율에 의한 것이었다.

• 한국세라믹학회지
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• 제12권1호
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• pp.16-22
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• 1975

The network structure of a glass is known to be cracked by a chemical reaction, diffusion, and ion exchange of alkali ion, formed at the crack tip of the glass surface, when water is present on the glass surface. Since the durability of glass is reduced, due to the fatigue phenomenon mentioned above, pollution problem of glass goods, especially bottle glass, is becoming acute gradually. A static fatigue phenomenon was studied thermodynamically in this paper, and a mechanism of static fatigue, a quality control, and a method of preventing pollution for the main local glass goods were also investigated. The PH of reacted solution and the quantity of extracted alkali were measured at different conditions such as temperature, reacting time, particle size of a crushed glass sample, and the nature of reacting solution. The enthalpy change was calculated from the Arrhenius equation. The results are given below; 1) The absolute value of enthalpy change for the bottle glass was found to be higher than the for the flat glass. 2) The fatigue phenomenon of a glass was more sensitive to the temperature than to the reacting time. 3) The durability of glass in acid solution is stronger than in alkaline solution. 4) The substance which cracks the network structure of glas is considered the hydroxyl ion.

• Composite Materials and Engineering
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• 제3권3호
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• pp.167-178
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• 2021

In the present paper, the destructive behavior of distilled water, salty water, sulfuric acid, and heat on glass/vinyl ester composites was investigated by experimental methods. Hetron 922 vinyl ester resin and two types of mat and woven glass fibers as the reinforcements were used to fabricate composite test samples. All samples were immersed in distilled water, salty water, and sulfuric acid with three different concentrations. The tests were performed at 20℃ and 70℃ for the exposure duration of 1, 2, 4, and 8 weeks. Bending tests were performed after aging for all composite samples to check the degradation of the bending modulus and strength. The results show that the effect of distilled water, in comparison with salty water, on the degradation of composite samples was significant. On the other hand, almost non-sensitivity of concentrations of salty water on the weight gain of specimens has been observed. In addition, it was also observed that the degradation of samples at 70℃ temperature is much more than that of at 20℃. Also, it was observed that the flexural modulus of virgin specimens exposed to salty water (2% concentration) has been recovered just after two weeks of immersion. Furthermore, in some cases, composite samples under the sulfuric acid solution have lost almost 80% of their mechanical properties.

• 대한치과보철학회지
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• 제47권2호
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• pp.119-124
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• 2009

연구목적: 치과 영역에서 환자들의 심미적인 요구가 증가하면서 자연 치아의 색조를 재현할 수 있는 수복물의 개발이 이루어졌으며, 이러한 연구의 일환으로 도재와 복합레진의 특성을 겸비한 Ceromer(Ceramic Optimized Polymer)가 개발되었다. Ceromer는 기존의 복합레진에 무기질을 고밀도로 충전하여 물리적 성질을 향상시켰다. 연구 재료 및 방법:본 실험에서는 두 종류의 Ceromer[$Targis^{(R)}$(Ivoclar-vivadent AG., Schaan, Liechtenstein), $BelleGlass^{(R)}$(Kerr Co., Orange, CA, USA)]를 이용해 레진 전장관 형태의 시편을 제작하고 증류수에 침전한 후 발생하는 체적과 중량의 변화를 관찰하였다. 결과 및 결론:두 종류의 Ceromer 모두 수중 침적 시간이 증가할수록 높이와 폭이 증가되었으며, $Targis^{(R)}$보다 $BelleGlass^{(R)}$에서 더 큰 누적변화율을 보였다. 72시간까지 급격한 증가를 보이다 이후 누적변화율의 증가는 감소하였다. 통계적 분석결과 $Targis^{(R)}$의 높이와 무게의 누적 변화량이 24시간군과 나머지군 사이에 유의한 차이를 보였으며, $BelleGlass^{(R)}$에서는 폭과 무게에서 누적 변화량이 24시간군과 나머지군 사이에 유의한 차이를 보였다(<.05). $Targis^{(R)}$와 $BelleGlass^{(R)}$ 두 군간의 비교에서는 높이, 폭, 무게의 변화량은 통계적으로 유의한 차이를 보이지 않았으나 변화양상은 다르게 관찰되었다.

• Journal of Korean Dental Science
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• 제16권1호
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• pp.74-79
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• 2023

Purpose: Cention N (Ivoclar Vivadent) was a recently introduced alkasite-based restorative material that was expected to replace amalgam and glass ionomer cement. This material was an esthetic restoration with adequate mechanical strength and release of fluoride and calcium. The purpose of this study was to measure the water sorption and water solubility of Cention N and evaluate its long-term durability compared to other esthetic restorations (Resin-Modified Glass Ionomer cement [RMGIC], Giomer, Composite Resin). Materials and Methods: Twenty specimens each of Cention N (CN), Resin Modified-Glass Ionomer Cement (FJ), Giomer (BF), and Composite Resin (FZ) were made. After each specimen was completely dried in a desiccator for 24 hours using a vacuum pressure pump, the specimen was weighed (m1). After that, the specimen was immersed in distilled water at 37℃ for 7 days, stored in a drying oven, and weighed (m2). After drying completely for 24 hours in a desiccator, the specimen was weighed (m3) to calculate the water absorption and water solubility using Formulas 1 and 2. The measured values were statistically processed and analyzed using SPSS, and the significance level was set at 0.05. Result: When measuring water sorption, FJ (122.61 ㎍/mm³) showed significantly higher water sorption than CN (35.42 ㎍/mm³) (P<0.05). There was no significant difference between FZ (18.03 ㎍/mm³) and BF (14.76 ㎍/mm³) (P=0.930). When measuring water solubility, CN (6.65 ㎍/mm³) showed significantly higher water solubility than FJ (1.47 ㎍/mm³) (P<0.05). Conclusion: Cention N had lower water sorption than RMGIC, but higher water solubility, indicating that it is more vulnerable to moisture and has lessened long-term durability.

• 한국소음진동공학회논문집
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• 제23권5호
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• pp.414-422
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• 2013

As structure-borne sound, the floor impact sound is one of the serious noises in residential building. Most of heating system applied to the typical Korean residential building is floor heating system which is called ondol. The ondol usually consists of finishing material, mortar with heating coil, light-weight aerated concrete and reinforced concrete. This study focused on the isolation of heavy-weight impact sound and modification of mortar and light-weight aerated concrete. Specifically the glass foam aggregate was added on light-weight aerated concrete. Also, water-cement ratio and amount of cement on mortar were revised. The sound pressure level of heavy-weight impact was measured in reverberation chamber using both bang-machine and impact ball. The size of specimen was 1 m by 1 m. Substitution ratio of glass foam aggregate on light-weight aerated concrete shows relationship with heavy-weight impact sound pressure level. In addition, heavy-weight impact sound pressure level was decreased with increment of water-cement ratio and amount of cement on mortar.