Composites of silica aerogels with organics: a review of synthesis and mechanical properties

Kyu‑Yeon Lee,Dinesh B. Mahadik,Vinayak G. Parale,박형호 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.1

Aerogels are considered as outstanding future materials owing to their wide surface area and three-dimensional network of silica particles, low density, low-thermal conductivity, high porosity, and low dielectric property. Their outstanding characteristics represent excellent potential applications in thermal insulation systems, aeronautical domains, environmental clean-up and protection, as heat storage devices, transparent windows, thickening agents in paints, etc. Among these applications, thermal insulating materials can play a vital role in living systems and for saving energy in various domestic and industrial processes. However, native silica aerogels are fragile and sensitive to relatively low pressures, which limit their application. More robust aerogels with higher strength and stiffness can be obtained by compounding silica networks with organoalkoxysilanes, polymers or using porous scaffolds as supports. This paper presents a review on the approaches for mechanical reinforcing methods for silica aerogels and recent achievements toward improving the strength of native silica aerogels. In addition, various characteristics derived from composite aerogels are analyzed synthetically.

제조에 對한 文獻的 考察

안태규,최병렬,송기철,이용연,유화승,서상훈,최우진,조정효,이연월,손창규,조종관 대전대학교 한방병원 2001 惠和醫學 Vol.10 No.1

In the literatual study on Holotrichia, the results were obtained as follows ; 1. Holotrichia is larva of Holotrichia diomphalia Bates etc. powder or liquor of Holotrichia is used medically. 2. Appearance of Holotrichia is shape of kidney, yellowish color. 3. The oriental characters of Holotrichia is warm, toxicant, salty. 4. The significant efficancy of Holotrichia is breaking the stagnant blood. 5. Holotrichia can be applied to the diseases related to thrombosis, and recover the demage of liver. 6. Holotrichia avails Liver diseases such as Hepatitis, Liver cirrhosis, Hepatosplenomegaly, Hepatoma etc.

眞空 蒸着法으로 製作한 PZT 薄膜의 電氣的 特性에 관한 硏究

延圭浩 충주대 2003 産業科學論文集 Vol.11 No.-

The effects of calcining temperature ranging from 700 to 1100℃ on sintering characteristics and electrical properties of Pb(Zr_0.53 Ti_0.47)O_3 doped with Nb_2O-5 has been investigated. The hardness as well as the density of the sintered increased with the calcining temperature from 700 to 900℃ and decreased beyoun 900℃, The X-ray diffraction pattern of the PZT sintered at 1200℃ for two hours showed both tetragonal and rhombohedral phases. The tetragonal phase peak increased with the calcining temperature going through a maximum at about 900℃, while the rhombohedral phase peak remained unaffected. The peaks of the both phases were almost the same for the samples calcined at 900℃. The activation energy decreased from 1.3 to 1.1eV below the curie temperature and increased from 0.65 to 1.05eV above that temperature.

BaTiO3 薄膜의 熱刺激電流 特性에 관한 硏究

연규호 韓國交通大學校 2013 한국교통대학교 논문집 Vol.48 No.-

In order to investigate the behaviors of carrier in dielectric thin films several characteristics such as thermally stimulated current, electrical conduction was observed on the specimen with 5000 [Å] thick. The forming condition of specimen fabricated as electret was as well as of electric field and that the observations on the characteristics of thermally stimulated current were carried out in the temperature range from -100 ] to 80 .

열자격 전류에 의한 ZnTe 박막의 주입 전하 거동에 관한 연구

延圭浩 충주대학교 1992 한국교통대학교 논문집 Vol.26 No.-

In order to investigate the behaviors of carrier in ZnTe thin film several characteristics such as thermaiiy stimulated current, injection current and electrical conduction were observed on the specimen with 6000 A thick. The forming condition of specimen fabricated electret was 8.0℃ as well as 1×10³∼ 1× 10(6) V/㎝ of electric field and that the observation on characteristics of thermally stimulated current carried out in the temperature from 120℃ to 150℃.

유전체 PET 박막의 Open 열자격전류 특성에 관한 연구

연규호 忠州大學校 2002 한국교통대학교 논문집 Vol.37 No.3

In order to investigate the behaviors of carrier in PET thin films several characteristics such as thermally stimulated current, electrical conduction was observed on the specimen with 8000[Å] thick. The evaporation were performed in 14 inch bell jar system evacuated by means of an oil diffusion pump in series with a mechanical pump. The pressure in the bell jar was less than [mmHg] the evaporation. In order to show that the preceding analysis of is any validity it is necessary to examine the characteristics of a material, that can be measured over a wide temperature without structural change.

ZnTe 박막소자의 트랩전하 특성에 관한 연구

延圭浩 충주대학교 1997 한국교통대학교 논문집 Vol.32 No.2

In order to investigate the behaviors of trap carrier in ZnTe thin film device several characteristics such as thermally stimulated current,trap current and electrical conduction were observed on the specimen with 6000Å thick. The forming condition specimen fabricated electric charge was 70℃as well as 1x10⁴~1x10??[V/cm] of electric field and the observation on characteristics of thermally stimulated current was carried out in the temperature from 100[˚K]to 400[˚K]

TiO2박막의 Open 열자격 전류 특성에 관한 연구

연규호 忠州大學校 2010 한국교통대학교 논문집 Vol.45 No.-

In order to investigate the behaviors of carrier in thin films several characteristics such as thermally stimulated current , electrical conduction was observed on the specimen with 6000 [Å] thick. The evaporation were performed in 14 inch bell jar system evacuated by means of an oil diffusion pump in series with a mechanical pump. The pressure in the bell jar was less than 5×10-7[㎜Hg] the evaporation. In order to show that the preceding analysis of is any validity it is necessary to examine the characteristics of a material, that can be measured over a wide temperature without structural change.

적산온도법에 의한 에폭시 모르터의 초기강도 예측에 관한 연구

연규석,大濱嘉彦,이윤수,김철영 강원대학교 부설 석재복합신소재 제품연구센터 1999 석재연 논문집 Vol.4 No.-

에폭시 모르터를 보수용으로 사용할 경우 거푸집의 회전율을 높이고 완전한 시공관리 차원에서 초기강도의 예측은 매우 중요하다 할 수 있다. 이에 본 연구는 결합재로서 에폭시 수지를 사용한 폴리머 모르터를 제조하고 경화제의 첨가량에 따른 초기강도의 변화를 시멘트 콘크리트에 적용되어 온 적산온도 방법에 의해 예측하는데 목적이 있다. 에폭시 모르터 제조에 사용된 재료는 반응성 희석제로 변성한 저점도형 Bisphenol-A계 액상 에폭시를 사용하였으며, 경화제는 지방족 Amine 변성 경화제를 사용하였다. 실험결과 에폭시 모르터의 기준온도는 -3∼-11℃로 나타났고, 경화제 첨가량에 따른 적산온도와 압축강도 사이의 강도 추정식은 다음과 같이 구할 수 있었다. 30% : Y = 292.42 Ln(M) - 881.16 40% : Y = 386.64 LN(M) - 1223.1 50% : Y = 273.18 LN(M) - 1040.5 Epoxy mortar is widely used to repair cement concrete structure and predicting strength of the mortar is of importance in its application. The objectives of this study were to compare the development of compressive strength of epoxy mortar with respect to maturity and to propose a predictive model for strength development of epoxy mortar. A series of tests were carried out for the hardener contents of 30, 40 and 50 percentage of resin and compressive strengths were measured at the age of 6, 12, 24, 72, 120 and 168 hours respectively under the cure temperature of 0, 10, 20 and 30℃. The datum temperature was estimated by measured strength, and the maturity was calculated with the estimated datum temperature. It was shown that the compressive strength of epoxy mortar could be predicted by regression analysis from the maturity-compressive strength relationship.

GaAs 반도체 내의 깊은 준위 측정에 관한 연구

연규호 忠州大學校 2012 한국교통대학교 논문집 Vol.47 No.-

Deep level transient spectroscopy (DLTS) has in recent years become a powerful technique in the characterization of semiconductor materials. In particular, the deep defect and impurity levels occurring in GaAs have received considerable attention, because of their adverse influence on the minority carrier lifetimes and efficiencies of electro-optical devices. In this paper, a detailed analysis of the pulsed bias techniques to determine the capture kinetics of the free carriers by deep traps in n type GaAs Schottky diode is introduced. Also a novel experimental technique is proposed to rigorously extract the experimental capture kinetics in the neutral semiconductor from the total capture kinetics; and thus, it is shown it is possible to obtain a correct estimation of the capture rate.