• Applied Biological Chemistry
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• v.15 no.2
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• pp.143-162
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• 1972

Based on the concentration of $^{40}K$ naturally occurring radioisotope of potassium, a method for the determination of total potassium in soils and plants was developed. The method was extended to evaluate the potassium supplying power of soils by taking the ratio of exchangeable potassium to total potassium $(K_{ex}/K_t)$, termed the potassium buffering capacity. Using this as index, it was observed that the release of potassium from soil fellows the from order reaction. A linear relationship was found between the potassium buffering capacity and the release constant of potassium or mica content of the clay. Similarly the potassium buffering capacity was also closely correlated with total uptake of potassium by rice plant. Hence it is concluded that the method for determining of the potassium buffering capacity could be veil applied to characterize the potassium availability of soils. The method for the determination of potassium is characterized by (1) The efficient measurement of the weak beta activity emissions from the samples, (2) identification of $^{40}K$, (3) calculation of total potassium content using the proportional constant of $^{40}K$ of samples to that of the standard. Difference in the potassium supplying power of soils due to soil types was also evaluated with the use of this technique. The degree of the potassium supplying power was in the order of soil types as red-yellow podzolic and lateric soils, basaltic materials(Rvd)> low-humic gley and alluvial soils, alluvial plains and food plains(Apa)> low-humic gley soils, nearly level to sloping local alluvial plains and slopes(Afb)> low-humic gley and alluvial soils, fluvio-marine plains (Fma).

• Economic and Environmental Geology
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• v.17 no.3
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• pp.197-214
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• 1984

This studg is to clarify intrusion sequence and petrogenetic processes of the so-called schistose granites in the northeastheastern part of the Kwangju, Chonnam Province. The study area is composed of the Pre-cambrian and Unknown age metasediments, the Unknown age schistose granites and basic plutons, the Cretaceous sedimentary and volcanic rocks, and the Cretaceous Ogang-ri granite and dykes. The schistose granites of the study area is divided into three rock units based on relative intrusion age, mineralogical constituent and texture;SoonChang schistose granite, two mica granite and Sam-o-ri schistose granite. The schistose granites intruded into metasediments, are intruded by Ogang-ri granite and dikes, and overlain by the Cretaceous sedimentary and volcanic rocks. The schistose granites vary widely in composition (granite-granodiorite-tonalite) and content of porphyroblastic feldspar Caugen and rectangular shaped). The foliation of schistose granites shows similar trend to the Shinian direction. In especially, strong foliation reflects dynamic metamorphism by mortar texture and much content of well oriented biotite. These schistose granites are characterized by its gray feldspar porphyroblasts. This feldspar is considered to be formed by potassic metasomatism and assimilation of pelitic metasediments of unexposed highly metamorphosed rocks deeply buried under the level of the schistose granites emplacement. Variation of silica versus oxides of major elements shows that the schistose granites are similar to the trend of Daly's average basalt-andesite-dacite-rhyolite which shows the trend of the fractional crystallization of magma. AMF diagram shows that the schistose granite is corresponded to contaminated differentiation products such as Lower California batholith and Cascade lava. These evidence suggest that the schistose granite is a series of differentiation products formed by fractional crystallization that associated with srtongly contamination and potassic metasomatism.

• Journal of the Mineralogical Society of Korea
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• v.13 no.4
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• pp.171-185
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• 2000

Siliceous mudstones are embedded on a large scale in the Tertiary formations of Pohang area. Some useful zeolites such as NsP, (Na, TMA)P, analcime and hydroxysodalite were synthesized from the siliceous mudstones by treating with the variety of solution, i.e ., NaOH, NaOH+NaCl, NaOH, NaOH+$NaAlO_2$and NaOH+TMAOH at the low-temperature hydrothermal system ranging 60~12$0^{\circ}C$. Major precursor of zeolites is found as opal-CT in the zeolite-forming reaction. Smectite, which is included in considerable amounts in the mudstone, appears to play a major role of Al-source in the zeolite synthesis. In comparison, chalcedonic quartz and mica are rather insoluble in alkaline solution, and thus, these are observed as major impurities in the reaction products. An addition of $NaAlO_2$to NaOH solution is effective for eliminating these impurities in the reaction procedure, through these are partly dissolved when elevating the reaction temperature, concentration, and time. Phase change from NaP to hydroxysodalite takes place at the NaOH concentrations of 3.0~4.0 M, and the reaction is not sensitive to the temperature shift. NaP is more stable at lower NaOH concentration and higher activity of $Na_{+}$ whereas analcime is sensitive to the temperature change and stable at higher than $100^{\circ}C$ and 2.0~4.0 M in NaOH concentration. For the pure NaP synthesis without any other products, the treatment of mudstones with 1:1 solution of NaOH and $NaAlO _2$ turns out to be quite effective. NaP was successfully synthesized together with analcime at $100^{\circ}C$ as well as lower concentrations of NaOH+NaCl solution. In addition, the organic type, (Na, TMA)P was formed together with smectite in the 1:1 solution of NaOH and TMAOH.

• 한국문화재보존과학회:학술대회논문집
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• 2004.10a
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• pp.33-42
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• 2004

The forged iron axe found in the No. 2 wood-framed tomb (the middle 3rd century) of Hwangseongdong, Gyeongju is rectangular on the plane level. It shows an obtuse angle in the edge part, while the joint part has the both sides folded up and shows the traces of wood. Under the reflected light, the Iron axe shines in metal luster, which is bright light gray or light creamy colors. The result of x-ray diffraction analysis shows that the axe consists of magnetite and geothite, which can explain why the composition and structure of the original ore has been kept intact. The microtexture of the axe has the irregular network of ferrite and pearlite, and tile cementite of tiny amount in the ferrite background. The overall treatment of the texture seems to be thermal with a high ratio of carbon. There are fine-grained magnetite, wolframite, quartz, calcite, mica, hornblende and pyroxene inside the axe. Those must be the impurities that they failed to remove in the refining process. The normal ferrite is composed of pure iron whose $Fe_2O_3$ proportion is from 99.16 to $99.84\;wt.\%$. Other than them, the ferrite parts usually contain $Al_2O_3\;and\;SiO_2$. The irregular network of pearlite also contains Impurities including $Al_2O_3\;and\;SiO_2$ and shows highly diverse patterns of carbon content. It's because the axe was carburized after the material was made to resemble pure iron. The decarbonization work didn't go well along the process marks. It's estimated that the original ore was bloom produced in low-temperature reduction and formed around in $727^{\circ}C$, which is eutetic temperature.

• Journal of Conservation Science
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• v.28 no.1
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• pp.7-20
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• 2012

This study was to identify the material characteristics and provenance of the Joseon (the 15th to 17th century) potteries from Ssangyongdong Yongam site in Cheonan. The pottery samples of the kilns and the workshops (habitation) from the study area have grey or red color with similar matrix but various shapes and different hardness, according to firing temperature. All of the pottery and the workshop soils were very similar patterns with characteristics of occurrences, mineralogy and geochemical evolution trend. But soils from around the site does not correspond with them. So the workshop soil that the fine clay is raw clay for making pottery in Yongam site. Firing temperature of soft-type potteries were presumed to be formed around $900^{\circ}C$ based on phase transition of clay minerals and mica. Hard-type pottery, mullite was detected and plagioclase was not detected by X-ray diffraction analysis, which means that potteries had experienced firing between 1,000 to $1,100^{\circ}C$.

• Geomechanics and Engineering
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• v.7 no.4
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• pp.375-401
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• 2014

It is generally accepted that material heterogeneity has a great influence on the deformation, strength, damage and failure modes of rock. This paper presents numerical simulation on rock failure process based on the characterization of rock heterogeneity by using a digital image processing (DIP) technique. The actual heterogeneity of rock at mesoscopic scale (characterized as minerals) is retrieved by using a vectorization transformation method based on the digital image of rock surface, and it is imported into a well-established numerical code Rock Failure Process Analysis (RFPA), in order to examine the effect of rock heterogeneity on the rock failure process. In this regard, the numerical model of rock could be built based on the actual characterization of the heterogeneity of rock at the meso-scale. Then, the images of granite are taken as an example to illustrate the implementation of DIP technique in simulating the rock failure process. Three numerical examples are presented to demonstrate the impact of actual rock heterogeneity due to spatial distribution of constituent mineral grains (e.g., feldspar, quartz and mica) on the macro-scale mechanical response, and the associated rock failure mechanism at the meso-scale level is clarified. The numerical results indicate that the shape and distribution of constituent mineral grains have a pronounced impact on stress distribution and concentration, which may further control the failure process of granite. The proposed method provides an efficient tool for studying the mechanical behaviors of heterogeneous rock and rock-like materials whose failure processes are strongly influenced by material heterogeneity.

• Journal of Adhesion and Interface
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• v.3 no.4
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• pp.44-52
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• 2002

Composite materials are created by combining two or more component to achieve desired properties which could not be obtained with the separate components. The use of reinforcing fillers, which can reduce material costs and improve certain properties, is increasing in thermoplastic polymer composites. Currently, various inorganic fillers such as talc, mica, clay, glass fiber and calcium carbonate are being incorporated into thermoplastic composites. Nevertheless, lignocellulose fibers have drawn attention due to their abundant availability, low cost and renewable nature. In recent, interest has grown in composites made from lignocellulose fiber in thermoplastic polymer matrices, particularly for low cost/high volume applications. In addition to high specific properties, lignocellulose fibers offer a number of benefits for lignocellulose fiber/thermoplastic polymer composites. These include low hardness, which minimize abrasion of the equipment during processing, relatively low density, biodegradability, and low cost on a unit-volume basis. In spite of the advantage mentioned above, the use of lignocellulose fibers in thermoplastic polymer composites has been plagued by difficulties in obtaining good dispersion and strong interfacial adhesion because lignocellulose fiber is hydrophilic and thermoplastic polymer is hydrophobic. The application of lignocellulose fibers as reinforcements in composite materials requires, just as for glass-fiber reinforced composites, a strong adhesion between the fiber and the matrix regardless of whether a traditional polymer matrix, a biodegradable polymer matrix or cement is used. Further this article gives a survey about physical and chemical treatment methods which improve the fiber matrix adhesion, their results and effects on the physical properties of composites. Coupling agents in lignocellulose fiber and polymer composites play a very important role in improving the compatibility and adhesion between polar lignocellulose fiber and non-polar polymeric matrices. In this article, we also review various kinds of coupling agent and interfacial mechanism or phenomena between lignocellulose fiber and thermoplastic polymer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.58-68
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• 1998

A computer-controlled system for measuring dielectric hysteresis has been developed. This system consists of the wave generation par\, the high voltage amplifier part, the measurement part, the data acquisition part and the related controll circuits and is interfaced to P.C(personal computer). The applied voltage and its frequency are controlled by P.C . Since the measured datas can be saved in the RAM of P.C, the analysis and the graphics of the datas are very convenient. As a accuracy test, the capcitances of the commercial mica and styroll capacitors were measured by applying high voltage and the results were good agreement with the rating values. In the test of PZT ceramic sample, the typical D-E hysteresis loops were obtained by applying a single frequency voltage to the sample, and $\varepsilon-E$ and D-E hysteresis loops could be measured at the same time by applying a double frequency voltage to the sample.sample.

• The Korean Journal of Quaternary Research
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• v.23 no.1
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• pp.1-24
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• 2009

Paleosol layers lying on top of the terrace in Jeongdongjin area appear to have been deposited under generally well-drained condition with periodic waterlogging. From a 4.5m-long profile observed, a total of 6 stratigraphic units were identified. Grain-size analysis indicates the dominance of silty and clay materials with some portions with high sand content. Major mineralogical elements are quartz, feldspar, mica and chlorite. Geo-chemical composition shows little change throughout the stratigraphy with some fluctuation in chemical weathering index. Marked increase in magnetic susceptibility is recognizable where stratigraphic unit changes. Soil- wedge layer is developed around 50cm below the surface with concentration of grains of AT tephra (c. 25,000 BP). An OSL date of c. 110,000 BP was obtained from a sand layer lying below the paleosol.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.159-166
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• 2008

We have a question about the changing possibility of orientation of discontinuities through the depth of under-ground. To know this, the data from Honam coalfield composed of shale, sandstone and coal and Suwon area which crops out mica schist, were analyzed the discontinuities measured by BIPS and Televiewer. In Honam coalfield the orientations of joints are changed at 30-40 m depth of underground and in Suwon area they are changed around 20 m depth. To compared the results from Honanam coalfield and Suwon area, there are different rock type and geologic structure. However, the attitude of the discontinuities are changing at 20-30 m depth of underground.