• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.209-211
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• 2008

본 연구에서는 실리케이트 적색 형광체의 신뢰성을 향상시키기 위하여 $SiO_2$ 박막을 졸-겔(sol-gel) 방법으로 코팅하였으며, 봉지재의 종류에 따른 코팅된 형광체의 신뢰성 변화를 조사하였다. 졸-겔 코팅 후 형광체 표면을 관찰한 결과 졸-겔 코팅이 잘 이루어 졌음을 알 수 있었으며, 4회 코팅 후 박막의 두께는 약 150nm였다. 코팅하지 않은 형광체의 경우 봉지재에 따른 차이는 있었지만 500시간 경과 후 효율 감소율은 30% 이상이었으며 코팅 한 형광체의 경우는 에폭시, JCR6175가 10${\sim}$25%, EG6301은 10% 이내의 효율 감소율을 보였다. 한편 색좌표 경우 에폭시 봉지재가 약 0.02의 변화를 EG6301 봉지재의 경우 0.01 이내의 변화를 보였다.

• 보존과학연구
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• s.30
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• pp.125-136
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• 2009

Stone cultural heritages in Korea have a severe damages from chemical and biological weathering because most of them have been situated in outdoors without any suitable protection systems, and this in turn causes deformation and structural damage. To counteract these problems and increase durability, various kinds of conservation materials are used in the conservation and restoration treatments. However until now there are not many practical and technological experiments on this subject. This paper attempts quantitative evaluation of effectiveness about chemical of ethylsilicate based resin for sandstone in Yeongyang-gun. It takes a long time to evaluate durability and side effect after conservation materials treatment. So we use artificial weathering through freezing§ thawing experimental method. As a result of this experiment, porosity and absorptance increased, and elastic wave speed, elastic modules, unconfined compression strength and tensile strength decreased more than before. This study plans to make a scientific method study about weathering factor and mechanism, and to deduce correlation between artificial weathering and natural weathering.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.11
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• pp.1020-1024
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• 2006

Europium$(Eu^{2+}\;or\;Eu^{3+})$-activated calcium aluminium silicate phosphors were synthesized for the first time and the structures and luminescence characteristics of these phosphors were investigated. The phosphors in this study emitted blue, green, and even red light depending on the starting milterials and annealing conditions for synthesis. In addition, the structure was also changed when the different starting materials were used. When $CaCO_3$ was used as a starting material, tetragonal $Ca_2Al_2SiO_7$ was formed. However, pure green light was emitted when the annealing was conducted in reduced atmosphere and red one was emitted by annealing in air. In the case of $CaSiO_3$ as a starting material, triclinic $CaAl_2Si_2O_8$ was formed and only pure blue emission was observed. Moreover, this blue phosphor exhibited higher intensity than that of commercial YAG:Ce phosphor, which showed the possibility of application on the phosphor for new light source such as a UV-LED.

• 보존과학연구
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• s.33
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• pp.69-83
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• 2012

Field experiments for Conservation damage on selected spots were carried out prior to direct conservation treatments for Bangudae Petroglyphs in Ulsan. It was found that there is a big difference in treatment effects according to the treatment technique and application rather than on the treatment material use. Based on the results of this study, a plan for the conservation treatment of Bangudae Petroglyphs will be suggested by providing new materials and application techniques for cracks, adhesive application and consolidation by conducting artificial weathering tests and continued monitoring.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.39-40
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• 2008

유기용매를 사용한 나노분산체의 경우, 유기용매를 완전하게 제거 것은 극히 어렵다. 이는 유기용매와 유기고분자와의 일부 반응되는 경우가 발생되어 전기적 물성에 영향을 줄 수 있다. 본 연구는 친환경적인 분산기법으로 물리적 분산기법을 제안하는 바이다. 양호한 분산체를 얻기위해 균질한 상태인 마이크로적 분산기법과 층상실리케이트인 층간사이에 고분자인 에폭시분자가 삽입되어 박리가 양호하게 일어나게 하는 나노적인 분산기법을 통시에 적용하여 분산이 훌륭하게 일어나는 경우를 개발하였다. 마이크로적인 분산을 위해 사용된 Homogenizer의 적용속도와 적용시간에서 원형인 Organoclay_10A Powder의 d-spacing이 262%, 263%로 증가되는 결과를 얻었다. 또한 DSC의 유리천이온도 분석에서도 적용시간의 증가에 따라 유리천이온도가 되어 원형에폭시수지에 비하여 $9^{\circ}C$상승된 결과를 얻을 수 있었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05b
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• pp.43-47
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• 2010

The use of high-strength concrete has increased for its excellent structural stability as buildings become higher and bigger than ever before in Korea and overseas recently. The functional requirement of building materials has also been bolstered so for the high -performance, high-quality construction materials to be used more extensively. However, the internal structure of the high-strength concrete is very dense so spalling can be caused during fire. The spalling in turn can cause critical structural damages followed by the fatal consequences, demolition of the building. Therefore, ensuring fire safety for high-rise buildings is assumed to be urgent. Alumino-silicate fire resistant board producing technology has been developed in situations that new materials with excellent fire resistance and easy installation has been sought. The alumino-silicate fire resistant board turned out to exhibit not only fire resistance and excellent physical and dynamical characteristics but also excellent onsite applicability and easy process and transportation after completing Mock-up test. Its excellence as a high-performance building materials was proven.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.4
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• pp.640-647
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• 1996

It has been found that an white precipitates at the inside surface is a common characteristics of soda-lime-silica glasses which have not undergone special surface treatments during hot weather season. In this study, the white deposits were examed using by solution method, surface analysis etc., and the dependence of weathering on the atmospheric condition was also investigated. As a results, the white precipitates on the glass surface was discorved as carbonates like $Na_2CO_3{\cdot}H_2O,CaCO_3$. Coming to atmosphere-dependence, it was shown that the glass made and stored at sea shore province had 3 times much severe weathering than that at land province.

• Polymer(Korea)
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• v.27 no.1
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• pp.75-83
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• 2003

Dicyanate-clay nanocomposite has been prepared by a melt in-situ polymerization method for different modifiers and cation exchange capacity (CEC) values in order to study dispersion and mechanical property. Various dicyanate nanocomposites were prepared by using different MMT systems containing different intercalants which led to different initial gallery heights and packing density. Depending on compatibility between dicyanate and clays, the degree of dispersion varied. Dispersion of clay plates in dicyanate resin depended mainly on CEC and aliphatic chain length of modifier. The lower CEC and shorter aliphatic chain length of modifier gave the exfoliation structure. It was also found that the reactivity of intercalant with dicyanate resin was one of the key factors facilitating the intercalation/exfoliation process of dicyanate/MMT nanocomposites. Shear modulus of reaction-induced dicyanate nanocomposite was significantly increased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.131-136
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• 2000

We have investigated the slurry induced metallic contaminations of undoped and doped silicate oxides surface on CMP cleaning process. The metallic contaminations by CMP slurry were evaluated in four different oxide films, such as plasma enhanced tetra-ethyl-orthyo-silicate glass(PE-TEOS), O3 boro-phos-pho-silicate glass(O3-BPSG), PE-BPSG, and phospho-silicate glass(PSG). All films were polished with KOH-based slurry prior to entering the post-CMP cleaner. The Total X-Ray fluorescence(TXRF) measurements showed that all oxide surfaces are heavily contaminated by potassium and calcium during polishing which is due to a CMP slurry. The polished O3-BPSG films presented higher potassium and calcium contaminations compared to PE-TEOS because of a mobile ions gettering ability of phosphorus. For PSG oxides, the slurry induced mobile ion contamination increased with an increase of phosphorus contents. In addition, the polishing removal rate of PSG oxides had a linear relationship as a function of phosphorus contents.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.418-419
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• 2006

We investigate the influence of the ambient gas during thermal annealing on the photoluminescence (PL) properties of europium-silicate thin films. The films were fabricated on substrates by using a radio-frequency magnetron sputtering method and subsequent rapid thermal annealing (RTA). The mechanism for the formation of the europium silicates during the annealing process was investigated by using X-ray diffraction (XRD) spectroscopy, Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). A series of narrow PL spectra from $Eu^{3+}$ ions was observed from the film annealed in $O_2$ ambient. Broad PL spectra associated with $Eu^{2+}$ ions, with a maximum intensity at 600 nm and a FWHM of 110 nm, were observed from the thin film annealed at $1000^{\circ}C$ in $N_2$ ambient.