• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.1
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• pp.141-150
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• 1988

Damping characteristics of chemically treated solls were studied by the use of FFT Analyzer and Bandwidth method. Also Modal Analysis was performed for the solidified silty sand samples. The soil samples were made of gravelly sand, sand, and silty sand, treated by water-glass chemical grouts. As the result of the study, it was found that the chemical grouting could be used for the vibration diminutinn effect as well as cut-off effect and strength improvement by the fact that the damping ratio of chemically treated soils was highly increased as the damping ratio of solidified soil was 0.11~0.22 and rathier high values in compare with the damping ratio of common soils which was 0.01~0.10.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.3
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• pp.99-106
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• 1990

This study was aimed to see the effect of chemical grout on fresh granite joint shear strength. The grouting chemical used in this study was composed of 25% water glass. Direct shear tests were performed on the chemical filled joints, which had been made artificially with granite. The test results show that chemical grouted rock jonts have markedly reduced shear strength comparing with the ungrouted fresh joints and they sheared within chemical grout before the rock to rock contact had been established, while the ungrouted joint sheared between rock surfaces from the beginning of shear deformation. With chemical grouted joints the shear stress slowly reached its maximum without showing distinct peak shear strength. Therefore the shear stiffness of joints were decreased with increasing thickness of grout. but the shear strain at failure was increased with it.

• Korean Journal of Optics and Photonics
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• v.9 no.4
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• pp.221-226
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• 1998

Ternary heavy metal oxide glasses in the $PbO-Bi_2O_3-Ga_2O_3$ system doped with $Er_2O_3$ were prepared and their spectroscopic properties, such as radiative transition probability, calculated and measured radiative lifetimes and cross-sections of 1.5 $\mu\textrm{m}$ and 2.7 $\mu\textrm{m}$ emissions were analyzed. Enhanced quantum efficiencies of some electronic transitions were evident mainly because of the low vibrational phonon energy ($~500cm^{-1}$) inherent in the host glasses. This seems to be the main reason for obtaining the 2.7 $\mu\textrm{m}$ luminescence which is normally quenched in the conventional oxide glasses. In addition, green and red fluorescence emissions were observed through the frequency upconversion processes of the 798 nm excitation. Non-radiative transition due to the multiphonon relaxation is a dominant lifetime-shortening mechanism in the 4f-4f transitions in $Er^{3+}$ ion except for the $^4S_{3/2}{\rightarrow}^4I_{15/2}$ transition where a non-radiative transfer to band-gap excitation of the host glasses is dominant. Melting of glasses under an inert gas atmosphere and (or) addition of the typical glass-network former into glasses is necessary in order to enhance the quantum efficiency of the transition.

• Proceedings of the Membrane Society of Korea Conference
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• 1992.04a
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• pp.33-34
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• 1992

현재 이용되는 막들은 대부분 유기계 혹은 고분자계로 열적인 안정성이 적고 내약품성이 낮다. 그래서 본 실험에서는 내열, 내약품성이 우수한 무기기와 유기기를 조합하여 복합막을 제조하려 시도하였다. 이때 유-무기 복합상의 반응은 졸-겔 법을 이용하였는데 이 졸-겔 법이란 출발물질인 금속알콕사이드를 용액상에서 가수분해하여 졸을 얻고 축합반응을 통해 겔을 형성하여 무기고분자를 제조하거나 소결하여 필름, 분말, 섬유상, 괴상 등의 다양한 형태로 산화물을 제조하는 공정이다. 이는 분자적 차원에서 혼합하여 반응하므로 산화물간의 반응보다 반응성의 입장에서 훨씬 유리하며 또한 용액상에서 저온반응 하므로 기존에는 유기-무기기를 조합하는데 존재하는 문제를 해결 할 수 있다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.202-202
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• 2010

불순물이 첨가되는 이원계 및 다원계 투명전도성 산화막들은 불순물의 첨가량에 따라서 전기적 그리고 광학적 특성의 변화를 나타낸다. 조성비에 따른 특성 변화를 조사하기 위하여 산화아연 타겟과 산화갈륨 타겟을 이용하여 혼합 스퍼터링 방식을 이용하여 인듐, 갈륨 등이 소량 첨가된 산화아연막(IGZO)을 증착하였다. Triple Co-sputter의 인가 전력을 변화시켜 가면서 박막 구성 원소들의 성분비 변화에 따른 전기적 그리고 광학적 특성을 조사하였다. 증착된 박막들은 조성비에 따라 전기적 그리고 광학적 특성이 변화되는 것을 확인하였다. 실온에서 유리기판 위에 증착된 박막은 저항률이 $2^*10^{-3}\;{\Omega}-cm$의 전기적 특성을 보였고, 투과도가 400~800nm 파장 범위 내에서 80% 이상의 광학적 특성을 보였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.2
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• pp.66-72
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• 2020

The difference of plasma resistance between the CAS glass bulk and coating films were compared. Plasma resistance was confirmed by analyzing the etch rate and the microstructure of the surface when the CAS glass bulk and the glass coating film were etched with CF₄/O₂/Ar plasma gas. CAS glass coating film was etched up to 25 times faster than the glass bulk. A statistically high correlation between the surface roughness and the etching rate of the coating film was derived, and thus, the high surface roughness of the coating film was determined to cause rapid etching. In addition, cristobalite crystals that has a low Ca content and a high Si content, was foamed on the glass coating film. Therefore, the CAS glass coating film is considered to have low plasma resistance compared to the glass bulk.

• Geotechnical Engineering
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• v.4 no.3
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• pp.53-62
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• 1988

When a ground soil is under the constant continuous stress less than the failure strength of that soil, its deformation, in some cases, will increase continuously as time goes on due to creep phenomena. Deformation of soil caused by creep behavior will appear in various types depending on the elastic, plastic, viscous properties of soil. Therefore in this study, visco-plastic characteristics of grouted soil was studied by analysing the result of uniaxial creep test on the grouted soil. As a result of this research, it was found that the rheological model of grouted soil can be decided as Vyalov model and the visco-plastic properties of grouted soil is influenced by the content of silicate in grout.

• Geotechnical Engineering
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• v.4 no.4
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• pp.29-38
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• 1988

One of the main objectives of researches for the chemical grouting is to assess the changes in soil properties caused by injection of chemical grout. Especially the changes in the strength properties of soils, such as elastic modulus, shear modulus of ground due to injection of chemical grout has drawn our attention. Since the specific surface changes with variation in the grain size of sandy soil, the influence of grain size of sandy toil on the strength and stiffness of silicate-grouted soil was investicated in this study by earring out uniaxial and triaxial compression tests. It was found that the strength and stiffness of grouted soil increased as the grain size of sandy soil decreases, the possibility of estimating the strength of grouted soil was confirmed through the study of relationship between specific surface of sandy soil and the strength of chemical gel.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.714-717
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• 2004

알루미노 보로실리케이트계 유리 기본조성 중 알칼리 토류 산화물의 종류 및 함량 변화에 따른 저유전율/저 LTCC 배선 기판의 저온 소성 거동 및 유전 특성을 조사하였다 알칼리 토류 산화물의 종류 및 함량 변화를 통해서 LTCC의 적정 소성온도인 $875^{\circ}C$ 부근을 포함하는 넓은 대역으로 소성수축이 시작되는 온도를 제어할 수 있었으며 유리 프리트와 알루미나 필러의 배합 비율의 변화에 따른 소성거동 및 유전특성의 변화 거동을 조사하였다. 알칼리 토류 산화물 중 유리 조성내의 CaO의 함량이 증가할수록 유리전이점 및 연화점을 증가하는 경향을 보였으며, 알루미나 필러의 첨가량이 증가할수록 소성수축이 시작되는 온도영역은 상향되고 유전율 및 품질계수는 증가하였다. 알칼리 토류 산화물의 조성과 필러인 알루미나의 함량을 제어함으로서 $875^{\circ}C$에서 18% 이상의 선수축율과 유전율 $5.1\sim5.5$ 및 유전손실 0.1% 이하의 우수한 특성을 갖는 저온소결용 LTCC 배선 기판을 얻을 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.337-337
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• 2009

가시광선영역에서 매우 균일한 높은 투과성뿐만 아니라 근적외선영역에서 가파른 홉수성 엣지와 함께 낮은 투과율을 제공하는 산화구리(II)를 함유하는 포스페이트 유리는 컬러 비디오 카메라의 컬러 보정 필터, 발광 컬러 디스플레이용 보호판(sheild), 모노크로메이터의 미광 필터, 플라스틱 복합재 필터의 무기 성분 및 CCD(전하 결합 소자) 및 CMOS(상보성 금속 산화물 반도체) 카메라 및 검출기 분야용 필터 유리로서 사용된다. 용융온도 및 산화구리(II) 첨가량에 따른 투과율을 측정하기 위해 포스페이트 유리 시료를 $1100\sim1500^{\circ}C$ 용융한 후 $400^{\circ}C$에서 2시간 동안 어닐링 공정을 거쳐 제조하였다. 제조된 시료는 두께 0.3mm로 폴리싱하여 자외선-적외선 분광 광도기를 이용하여 광학적 특성을 측정하였다. 본 실험을 통하여 용융온도에 따라 가시광선영역 및 근적외선영역에서의 투과율 거동을 비교한 결과 $1100\sim1200^{\circ}C$에서의 우수한 투과율 특성을 나타냈다. 용융온도가 내려감에 따른 가시광선영역 (400~600nm)에서 높은 투과율 및 근적외선영역 (750~1100nm)에서 낮은 투과율과 가파른 흡수성 엣지를 나타냈다.