• 한국토양비료학회지
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• 제49권1호
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• pp.53-59
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• 2016

This study deals with the distribution of the clay minerals separated from clay fractions of ranch pastures in Korea and their chemical and mineralogical properties. Crystalline phases of the clay minerals were identified by powder X-ray diffraction (XRD) pattern and FT-IR spectra, and their relative chemical compositions were also analyzed by X-ray flourescence spectrometry (XRF). Primary minerals consisted mainly of quartz and mica and chlorite and kaolinite along with a trace of swelling micas were identified as secondary clay minerals. However, the relative content of these clay minerals was different with the locations, which led to significant effects on physical and chemical properties of soils like inorganic elemental composition. In particular, $SiO_2$ content was higher in Gochang ranch pasture than in other ranch pasture. Infrared (IR) spectra did not indicate any significant differences in organic functional groups among the locations. This study clearly showed that ranch pastures had different relative content of clay minerals and chemical properties depending on the location and consequently that those properties are worthy to be taken into account for soil amendment.

• 한국토양비료학회지
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• 제49권6호
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• pp.813-818
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• 2016

Distribution of clay minerals separated from clay fraction of corn fields in Korea has been investigated along with their characterization. Crystalline phases of the clay minerals were identified by powder X-ray diffraction (XRD) pattern, and their relative chemical compositions were analyzed by X-ray fluorescence spectrometry (XRF). The soils were found to have pH 6.4, organic matter $37.2g\;kg^{-1}$, available $P_2O_5$ $599mg\;kg^{-1}$, respectively, and exchangeable K, Ca and Mg were 1.2, 7.3 and $1.8cmol_c\;kg^{-1}$, respectively. Major primary minerals consisted mainly of quartz and mica, and kaolinite and chlorite were identified as major secondary clay minerals. For most of soils, mica phase was identified to be muscovite rather than biotite. The average contents of $SiO_2$, $Al_2O_3$ and $Fe_2O_3$ were 43.7, 23.6 and 8.8%, respectively, although they were different with the locations.

• Structural Engineering and Mechanics
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• 제77권1호
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• pp.103-114
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• 2021

Ultra high strength concrete (UHSC) originally proposed by Richards and Cheyrezy (1995) composed of cement, silica fume, quartz sand, quartz powder, steel fibers, superplasticizer etc. Later, other ingredients such as fly ash, GGBS, metakaoline, copper slag, fine aggregate of different sizes have been added to original UHSC. In the present investigation, the combined effect of coarse aggregate (6mm - 10mm) and steel fibers (0.50%, 1.0% and 1.5%) has been studied on UHSC mixes to evaluate mechanical and fracture properties. Compressive strength, split tensile strength and modulus of elasticity were determined for the three UHSC mixes. Size dependent fracture energy was evaluated by using RILEM work of fracture and size independent fracture energy was evaluated by using (i) RILEM work of fracture with tail correction to load - deflection plot (ii) boundary effect method. The constitutive relationship between the residual stress carrying capacity (σ) and the corresponding crack opening (w) has been constructed in an inverse manner based on the concept of a non-linear hinge from the load-crack mouth opening plots of notched three-point bend beams. It was found that (i) the size independent fracture energy obtained by using above two approaches yielded similar value and (ii) tensile stress increases with the increase of % of fibers. These two fracture properties will be very much useful for the analysis of cracked concrete structural components.

• 한국결정학회지
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• 제12권4호
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• pp.216-221
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• 2001

채석장 및 서재 가공장에서 폐기되는 미립의 분말의 석분 슬러지를 활용하고자 수영양생법으로 인조 석판재를 제조하였다. 석분 슬러지의 주성분은 석영 및 알루이나로서 여기에소석회 및 규사를 첨가하여 증기압, 수열 반응시간, 소석회의 첨가량 등이 인조석판재의 강도 및 비중에 미치는 영향을 조사하여 수열양샡법을 적용한 인조석재 제조공정을 확립하고자 하였다. 석분 슬러지 70%, 소석회 20% 및 규사 10%에 수분 10% 비율로 혼합한 후 200kg/㎠의 압력으로 성형하여 증기압이 20kg/㎠인 조건으로 3시간 동안 반응시켜 제조한 인조석재는 압축강동 614kg/㎠흡수율 0.48%, 겉보기 비중 1.88인 물성을 나타내었다. 또한 각종 산화물계 안료의 첨가에 의하여 다양한 색상과 문양을 보유한 인조석재의 제조가 가능하였다.

• 청정기술
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• 제4권1호
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• pp.35-44
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• 1998

휘발성 유기화합물(벤젠, 톨루엔, 에틸벤젠, 크실렌)의 광분해를 단순 UV조사와 $TiO_2$ 광촉매하의 UV조사를 이용하여 연구하였고 또한 여러 가지 반응조건에 따른 분해효율에 대해 고찰하였다. 광분해반응기는 중압 수은램프가 부착된 석영 annular 반응기를 이용하였다. UV조사에 의한 휘발성유기화합물의 분해정도는 톨루엔 92% ${\geq}$ 에틸벤젠 92% > 벤젠 83% > 크실렌 82% 였고, $TiO_2$ 광촉매하의 UV조사를 이용한 유기물의 분해정도는 톨루엔 92% > 크실렌 82% > 에틸벤젠 80% > 벤젠 53% 였다. 반응물의 분석은 Purge & Trap 농축기를 이용하여 FID가 부착된 GC로 분석하였고, GC-MS로 반응물의 중간생성물을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제30권9호
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• pp.1978-1980
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• 2009

A mesostructured form of carbon was fabricated from a template of mesostructured silica by using pentane, an aliphatic hydrocarbon precursor. To synthesize the mesostructured silica, a buffered (pH of 6.5) mixture of nonionic Pluronic P123 surfactant, sodium silicate, and acetic acid were used. The impregnated silica with Fe$(CO)_5$ (wt 5%) and pentane was placed in a quartz tube, treated with pentane vapor at 800 ${^{\circ}C}$ for two hours to synthesize the mesostructured carbon. The XRD patterns of the carbon replica in the low/wide angle regions, its TEM images, and nitrogen adsorption-desorption isotherm revealed that the long-range framework order of mesostructure with the pore size centered on 2.8 nm was maintained to some extent mainly due to some portions of mesophase carbon that work as a support to fix the hexagonal frameworks by anchoring on the pore surface with an improved graphitic character. The dc conductivity of the mesostructured carbon in pressed powder form at 6.0 MPa was 2.08 S/cm.

• 한국지반공학회지:지반
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• 제4권3호
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• pp.27-34
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• 1988

고변형률을 받는 모래는 비선형 거동을 나타내게 된다. 본 연구에서는 석영질 모래의 공극비와 미세입자 (석영분말)함량을 변화시키면서 모래의 고변형률 진통특성을 공진주 실험을 이용하여 조사 하였다. 그 결과 석영분말을 취음에 따라 전단탄성계수와 감쇠비는 석영분말의 함량을 증가시킬수록 전단변형률에 대한 변화가 점점 더 완만하였고 공극비의 변화에 대해서는 그 변화가 두드러지지 못 하였다. 또한 Rainberg-Osgood방적식을 써서 흙의 진동특성과 전단변형률파의 관계를 고찰하였는 바 전 단탄성계수와 감쇠비 모두의 경우 R은 2.0정도이나 C는 시료상태 및 구속압력에 따라 200에서 3200까지의 큰 변화를 나타내었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.711-714
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• 2005

This paper focused on development of geopolymer for wood wool ceramic board. Geopolymer can substitude ordinary portland cement and its accelerator of wood wool cement board as inorganic polymer. In this study, what we would obtain geopolymer's properties such as initial setting time(KS L 5108), flow(KS L 5102) and compressive strength of 3days aged(KS L 5105), was less than 1 hour, more than $110\%$, more than 40Mpa. Geopolymer have three essential materials called filler, hardener and geopolymer liquor. So, We applied filler by quartz, hardener by blast furnace slag powder, metakaoline and fly ash, geopolymer liquor by NaOH, KOH and sodium silicate solution. As result of this experiment, what we could obtain best fitted geopolymer's properties such as initial setting time, flow and compressive strength of 3days aged, was 45min, $116\%$ and 43.6Mpa. This result can be applicable to commercial wood wool ceramic board.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.159-162
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• 2000

The purpose of this study is to develope an accurate procedure for measuring the glass content of fly ash produced by bituminous coal to assist in predicting their behavior in concrete. Quantitative mineralogical compositions of fly ashes were obtained by internal standard method using powder X-ray diffraction analysis. In the X-ray diffraction method, the specimen and standard fluorite were cautiously mixed and pulverized to 22$\mu$m in wet process so as to avoid the prefered orientation of the crystal and microabsorption effect of X-ray. calibration curve were fitted for several references peaks of four phases:$\alpha$-quartz. mullite, magnetite, hematite. The amount of glass was calculated by subtracting the amount of crystal phase and loss on ignition from the total amount. Glass content determined with this method ranged from 66.7 to 75.wt%.

• 한국세라믹학회지
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• 제46권4호
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• pp.385-391
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• 2009

Need for plasma resistant ceramic materials has been continuously increased in semiconductor and display industry requiring plasma processing to realize ultra fine circuit process. Among promising candidates, alumina ceramics have still some advantages with respect to its economic aspect. In this study, fabrication of plasma resistant alumina ceramics was tried, and its processing optimization was also aimed. Careful processing control and thereby uniform microstructure of $Al_2O_3$ gave rise to enhanced plasma resistance, even comparable to market-governing commercial $Al_2O_3$. A further study is needed concerning ${\beta}-Al_2O_3$ materials system, presumably playing a decisive role in decreasing plasma resistance of $Al_2O_3$ ceramics.