• The Journal of Engineering Geology
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• v.15 no.2 s.42
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• pp.105-121
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• 2005

Most of the landslides triggered by intensive rainfall on natural slope occur serious damages of human beings and properties. There have been many landslides since 1991 in Gyeonggi province. The influential factors are rainfall, topography, geology and soil properties. There were 660 landslides occurred by intensive rainfall as much as 250mm at Yongin and Anseong area from Tuly 19th to luly 21st,1991 This study surveyed location, topography, geology, geometry of the landslide and rainfall at the area and analyzed occurrence characteristics of the landslides. Most of the landslides occurred on the soil layer above the bed rock. They showed changes of landslide types from translational slides at the head part to flow at the central part. The landslides have relatively small magnitude of which length is shorter than 50m. In order to identify characteristics of landslides dependent on soil conditions, geotechnical properties of soil were evaluated by laboratory tests using soil samples which were collected on slided area and not-slided area. Soil properties of the slided area show high percentage of coarse material such as gravel and sand. However, soil of the not-slided area is mainly composed of fine material such as silt and clay. Permeability coefficients of the slided area are higher than those of the not-slided area.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.804-810
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• 2003

The fine powder produced by heating and grinding of the waste concrete in the waste construction was investigated whether utilize as substitution raw material of SiO$_2$, CaO, and Al$_2$O$_3$ source for OPC clinker manufacture is possible or not. In order to synthesize OPC clinker, limestone, shale, converter slag and fly ash were used as main raw materials, and modulus was fixed LSF 91.0, SM 2.60, IM 1.60. The synthesized clinkers were characterized. The Main products of synthesized clinker were C$_3$S, ${\beta}$-C$_2$S, C$_3$A, C$_4$AF as OPC clinker at 1,43$^{\circ}C$. As a result of TG-DTA and burnability index(B.U) analysis of each raw mixtures, the formation temperature of clinker phases was similar and B.I was showed easy burning as 48.6∼51.4.

• The Journal of the Petrological Society of Korea
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• v.23 no.4
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• pp.337-349
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• 2014

We measured rare earth element and Zr concentrations of USGS granite standard material GSP-2 and GSJ granite standard material JG-1a to clarify the effect of zircon during rare earth element analysis using ICP-MS. We also measured rare-earth element and zirconium (Zr) contents of zircon from granite by acid-digestion methods using conventional teflon vial and pressure-bomb. The results show that acid-digestion using teflon vial dissolved ca. 50% of zircon compared to pressure-bomb method. The Zr contents of JG-1a and GSP-2 gave ca 50% of reference value. However, rare-earth element abundance of JG-1a and GSP-2 were similar to those of reference values. This suggests that the decomposition degree of zircon might give a negligible effect on a petrological and geochemical interpretation using chondritenormalized REE pattern.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.3
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• pp.225-228
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• 2011

This study evaluated the mineral crystalline structure of an autogenous tooth bone graft material. The crystalline structures of the autogenous tooth bone graft material enamel (AutoBT E+), dentin (AutoBT D+), xenograft (BioOss), alloplastic material (MBCP), allograft (ICB) and autogenous mandibular cortical bone were compared using XRD. The XRD pattern of AutoBT dentin and ICB was similar to that of autogenous bone.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1062-1066
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• 2003

Design of a piezoelectric actuator for the ultrasonic motor must ensure that contact point has elliptic trajectory of movement. The new idea of an elliptic trajectory formation of the piezoelectric actuator is investigated in the paper. Shaking beam for the piezoelectric linear ultrasonic motor was introduced to realize this new idea. The principle is based on the excitation of longitudinal and flexural vibrations of the actuator by using two sources of longitudinal mechanical vibrations shifted by $\pi$/2. Mode-frequency and harmonic response analyses of the actuator based on FEM have been carried out. The moving trajectory of the contact point has been defined. Finally, The experimental research of shaking beam has been confirmed an opportunity of the elliptic trajectory reception with the help of one stable mode of the vibrations.

• Journal of the Korea Institute of Building Construction
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• v.4 no.4
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• pp.87-94
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• 2004

As the bentonite is main material to prevent from collapse of drilling hole at underground excavation works, it is increased using quantity on construction industry day by day. But, the discarded bentonite that is over using at underground excavation works is caused various enviromental trouble as soil and water pollution est. Therefore, this study aims to propose a foundamental report for pozzolan reaction of discarded Bentonite powder by heat-treatment and cooling as concrete mineral admixture. To find out pozzolan reaction ability of discarded Bentonite powder by indirect cooling & cooling using of water after heat-treatment, the experiments are excuted flow test & compressive strength on age of mortar using discarded Bentonite powder. As a result of this study, discarded Bentonite powder can be utilized as concrete mineral admixture by heat-treatment and especially, pozzolan reaction ability of discarded Bentonite powder is superior to the situation of 600℃. 60min ＆amp; cooling using of water.

• Geomechanics and Engineering
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• v.15 no.2
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• pp.729-738
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• 2018

Soft clay soils due to their various geotechnical problems, stabilized with different additives. Traditional additives such as cement and lime will not able to increase the soil strength properties significantly. So, it seems necessary to use new additives for increasing strength parameters of soft clay soils significantly. Among the new additives, epoxy resins have excellent physical and mechanical properties, low shrinkage, excellent resistance to chemicals and corrosive materials, etc. So, in this research, epoxy resin used for stabilization of soft clay soils. For comprehensive study, three clay soil samples with different PI and various clay mineral types were studied. A series of uniaxial tests, SEM and XRD analysis conducted on the samples. The results show that using epoxy resin increases the strength parameters such as UCS, elastic modulus and material toughness about 100 to 500 times which the increase was dependent on the type of clay minerals type in the soil. Also, In addition to water conservation, the best efficiency in the weakest and most sensitive soils is the prominent results of stabilization by epoxy resin which can be used in different climatic zones, especially in hot and dry and equatorial climate which will be faced with water scarcity.

• Journal of the Mineralogical Society of Korea
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• v.20 no.3
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• pp.155-163
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• 2007

A novel route to the synthesis of tetramethoxysilane and other silicon alkoxides is described using siliceous mudstone as the raw material. The reaction of amorphous silica with triethanol-amine is enhanced by using an alkali metal hydroxide catalyst to form a range of triethanol-amnine-substituted silatrane species. These can undergo alkoxide exchange in acidic alcohols to form alkoxysilatranes, tetraalkoxysilanes, hexaalkoxydisiloxanes and higher siloxanes. Products were identified by FT-IR spectroscopy, XRD, SEM, 1H and 13C NMR spectroscopy, or gas chromatography.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.589-594
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• 2011

Raw mix of molten clinker was fabricated using blast furnace slag as starting material. Raw mix was melted at 1620$^{\circ}C$ for molten clinker fabrication. It was found that molten clinker contained alite and belite equivalent to OPC clinker mineral by optical microscope and SEM. The size of alite was 10~50 ${\mu}m$ and that of belite was 20~80 ${\mu}m$. This result thought to be attributed low $Al_2O_3$ content and cooling condition. Interstitial phase increased with blast furnace slag content and gehlenite was formed by the condition of LSF and SM. So raw mix with 27~41% blast furnace slag could be converted into cement clinker by appropriate choice of melting andcooling methods in this study.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.4
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• pp.309-314
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• 1987

This study was conducted to examine mineralogical aspects on anthractite and bituminous coal-fired power-plant ashes as a source of mineral fertilizer. Fly ashes contain dominant amounts of silica and alumina and considerable quantitites of potassium and boron. However, potassium and silica present in unavailable forms for plant growth. X-ray, DTA, and IR analysis of ash particles indicated the formation of new mineral, mullite with shape of which were spherical in the surface morphologies of SEM. Detailed SEM investigation showed the presence of imbedded blocky shape silicate material.