• Industry Promotion Research
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• v.9 no.1
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• pp.31-38
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• 2024

In this study, evaluated the properties of layered silicate-based nanocomposite sensitive film. For the fabrication of nanocomposite materials, we selected organically modified layered silicate materials, specifically Cloisite^® and Bentone^®, which were treated with quaternary ammonium salts. The impedance of the humidity sensors containing organically modified montmorillonite/hectorite clay decreased with increasing relative humidity(RH%). In the case of the Cloisite^® humidity sensor exhibited slightly better impedance linearity and hysteresis compared to the Bentone^® 38 humidity sensor. Additionally the impedance of the sensor with Bentone^® 38 addition was the lowest when compared to the Cloisite^®-modified sensor. Comparing the Cloisite^®-modified sensors individually, we observed different moisture absorption characteristics based on the hydrophilic properties of the organic-treated materials. The response speed of Cloisite^® 93A tended to be slower due to differences in moisture evaporation rates influenced by the hydrophilic organic components. Based on these results, moisture barriers utilizing organically modified layered silicate materials may exhibit slightly lower moisture absorption properties compared to conventional polymer-based moisture barriers. However, their excellent stability, simple processing, and cost-effectiveness make them suitable for humidity sensor applications.

• The Journal of the Korean dental association
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• v.58 no.7
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• pp.435-442
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• 2020

Porcelain is the first ceramic material to be introduced into dentistry. Porcelain jacket crown was introduced by Dr. Charles H Land in 1886, which was an excellent aesthetic dental restoration but has not been widely used due to high firing shrinkage and low tensile strength. Then metal-ceramic system, which combines the esthetic properties of ceramics and the mechanical properties of metals, was introduced and nowadays it is still used in dental clinical field. However, the metal-ceramic system has shown some problems, such as increased lightness by reflection of light at opaque layer, shadow beneath the gingival line due to the block-out of light by metal coping, exposure of metal in margin part, bond failure between metal and porcelain, oxidation of metal coping during firing the porcelain, etc. Recently, along with the advance of fabrication methods of dental ceramics, the all-ceramic restorations with high esthetic and mechanical properties has increased and gradually replaced metal-ceramic restorations. Especially, CAD/CAM technology has opened a new era in fabricating the dental ceramic restorations. This overview will take a look at the past, present and future possibility of the dental ceramic materials.

• 한국문화재보존과학회:학술대회논문집
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• 2006.04a
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• pp.75-77
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• 2006

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1188-1195
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• 1999

The effect of aluminosilicate sol on the formation of mullite layer in zircon shell mold was investigated. Aluminosilicate sol was prepared by mixing of colloidal silica(NALCO(R) 1130) and an aqueous solution of aluminium nitrate at room temperature. The sol gelled at 50$^{\circ}C$ for 48 hrs. It was identified that the gel consists of aluminosilicate complexes and gibbsite. The coordination number of all aluminium ion bonded with silicon ion was four. Mullite phase formed by sintering above 1300$^{\circ}C$. XRD peak of mullite sharpened with increasing sintering temperature and the content of aluminium nitrate. Mullite phase displayed whisker-like 0.5~5${\mu}m $ particles. Separation between 1st and 3rd layers during sintering and the difference in thermal expansion coefficient between residual silica and mullite.

• Proceedings of the Korean Society of Rheology Conference
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• 2000.05a
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• pp.19-22
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• 2000

• Magazine of the Korea Concrete Institute
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• v.27 no.1
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• pp.22-26
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• 2015

• Journal of the Korea Institute of Building Construction
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• v.18 no.6
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• pp.569-576
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• 2018

In modern society, a huge number of the buildings have been constructed with RC structure. RC structures have many structural instabilities due to earthquake, typhoon, construction fault, design phase errors. Therefore, many reinforcement methods are being implemented to solve this problem. In the reinforcement method, the organic epoxy adhesive used in the FRP reinforcing method is abruptly damaged when exposed to high temperature, which is directly connected to the fall of the reinforcing material. Therefore, the present study was conducted to develop inorganic refractory mortar with a certain level of adhesion ability to reduce the heat transferred to FRP reinforcement when exposed to high temperatures. As a result of the test, it showed high adhesion strength at room temperature condition with the inclusion of EVA resin, and showed no performance deterioration up to about $300^{\circ}C$ even under heating conditions. Also, it was confirmed that the backside temperature was lower as the thickness increased, and converged to a constant temperature of about $780^{\circ}C$ after 2 hours of heating.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.625-628
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• 2006

It is known that cement production not only consumes large amount of energy but also contributes substantially to the green house gas emission. Therefore, there is a demand to develope a new technology to produce energy efficient and environmental conscious cements. The most recent, wood wool ceramic board is being applied in various building material field, for example thermal insulating and acoustic absorption material. This paper focused on improvement of alumino-silicate binder's physical properties for wood wool ceramic board. As the result of this experiment, what we could obtain best fitted alumino-silicate binder's properties such as initial setting time, flow and compressive strength of 3 days aged, was 58min, 110% and 66.0Mpa. This result can be applicable to commercial wood wool ceramic board.

• Journal of Welding and Joining
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• v.20 no.3
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• pp.116-121
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• 2002

For the accumulation of a fundamental knowledge about the behavior of glass solder during the joining of ceramics, the wettability of solder on silicon nitride have been measured by sessile drop method. $SiO_2-MgO-Al_2O_3$ g1ass solder and oxynitride glass solders were selected as examples while silicon nitride which were used as substrates. Contact angle of solder on silicon nitride didn't decrease with time at high nitrogen content in the solder, but low nitrogen content in solders have the time-dependent property. Reason which contact angle of low nitrogen content in solders decrease on silicon nitride was that diffusion of nitrogen take place between solder and silicon nitride.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.91-94
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• 2007

It is essential every concrete structure should continue to perform its intended functions, that is maintain its required strength and durability, during the service life. However, deterioration occurs more progressively from the outside of concrete exposed to severe conditions. Deterioration in the concrete structure is due to carbonation and chloride ion attack. Therefore, concrete structure is needed to surface protection for increase durability using impregnant. Impregnant classify into two large groups in polymeric and silicate materials. Silicate impregnant is included silane and alkali silicate(sodium and lithium silicate). Thus, this study is concerned with carbonation and chloride ion resistance of self cleaning hydrophilic impregnant of concrete structure using lithium and potassium silicate. From the experimental test result, lithium and potassium silicate have a good properties as a carbonation and chloride ion resistance. Lithium and potassium silicate make good use of hydrophilic impregnant.