• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.563-572
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• 2006

In order to propose optimum in-situ treatment for reducing phosphorous release from sediment of stationary lakes, a series of column tests were performed. The sediment used in experiment was very fine clay with a mean grain site $7.7{\phi}$ and high $C_{org}$ contents(2.4%). Phosphorous releases were evaluated in two ways : in lake water(with microbial effect) and in distilled water(without microbial effect). As in-situ capping material, sand and loess were used while Fe-Gypsum and $SiO_2$-Gypsum were used for in-situ chemical treatment. In case of lake water considering the effect of microorganism, phosphorous concentration rapidly decreased in the early stage of experiment but it was gradually increased after 10 days. Flux of phosphorous release for control was $3.0mg/m^2{\cdot}d$. Whereas, those for sand layer capping(5 cm) and loess layer capping(5 cm) were $2.5mg/m^2{\cdot}d\;and\;1.8mg/m^2{\cdot}d$, respectively because the latter two were not consolidated sufficiently. For Fe-gypsum and $SiO_2$-gypsum the fluxes were $1.4mg/m^2{\cdot}d$ which meant that reduction efficiency of phosphorous release was more than 40% higher than that of control. The case capping with complex layer was $1.0mg/m^2{\cdot}d$, which showed high reduction efficiency over 60%. The addition of gypsum($CaSO_4{\cdot}2H_2O$) into the sediment reduced release of Phosphorus from the sediments. Gypsum acted as a slow-releasing source of sulphate in sediment, which enhanced the activity of SRB(sulfate reducing bacteria) and improved the overall mineralization rate of organic matter.

• Journal of the Mineralogical Society of Korea
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• v.9 no.2
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• pp.102-112
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• 1996

The precious serpentine, referring to a rare and highly valuable gem variety of serpentine group minerals, is found to occur in serpentinite from Booyo Gren Jade Mine which is located in Oesan-myun, Booyo-gun of Chungchungnam-do. Geommological properties of the precious serpentine have been investigated by use of polarizing microscope, specific gravity balance, refractometer, hardness pencils, X-ray diffractometer, XRF, ICP-MS analyser, and infrared absorption spectroscope.The precious serpentine from Booyo is colored deep green with oily luster and semi-transparent. It is highly tough and Mohs's scale of hardness is measured to be 5-6. Specific gravity is determined to be 2.67, and a single refractive index ND=1.56 is observed by a spot method, using sodium light source. X-ray powder diffraction data is represented by the reflection lines at 7.40(100), 4.64(25), 3.68(68), 2.757(69), 2.530(49), 2.549(32), and 1.710(21${\AA}$), which compares very well with that of antigorite of serpentine group minerals. The major chemical compositions of the precious serpentine group minerals. The major chemical compositions of the precious serpentine are SiO2 42.49%, MgO 39.08%, Fe2O3 3.85%, and H2O 11.87%. Besides, trace elements such as Cr(2188), Ni(1110ppm), Co(58ppm), and Ta (108ppm) are relatively spectrum shows peaks at 3670, 1190, 1070, 980 and 610cm-1. Strong absorption at 3670cm-1 is due to OH stretching, and 1190, 1070 and 980cm-1 due to SiO stretching. The absorption 610cm-1 is formed by alteration of pre-existing ultramafic rock, namely peridotite, with an introduction of fluid with very little content of CO2, under 400$^{\circ}C$ environment. Magnetite inclusions, finely disseminated in the precious serpentine, may be a result of Fe precipitation, during serpentinization of olivine-bearing country rock.

• Journal of the Korean GEO-environmental Society
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• v.20 no.1
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• pp.5-11
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• 2019

The main objective of this study was to analyse polycyclic aromatic hydrocarbons in surface sediments obtained from near Nakdong estuary, and to estimate ecological risks of PAHs using PAHs concentrations. The main constituents of sediments were $SiO_2$, $Al_2O_3$, CaO, $Fe_2O_3$, and ignition loss of sediments ranged from 2.97% and 8.39%. Total concentrations of PAHs ranged from $128.4ng\;g^{-1}$ and $507.4ng\;g^{-1}$, and the major PAHs were 2 ring and 4 ring aromatic hydrocarbons. Each concentrations of PAHs are all below effect range low, which indicated that each PAHs in 8 studying sites show low ecological risk. From M-ERM-Q analyses, M-ERM-Q values of 8 studying sites are below 0.1 indicating low ecological risk. From source apportionment analyses, PAHs come from grass, wood, charcoal combustion for N-1 and N-7, petroleum combustion for N-5 and N-6, petroleum pollution for N-2, N-3, N-4, N-8.

• Advances in environmental research
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• v.4 no.2
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• pp.69-81
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• 2015

A new magnetite-silica core/shell nanocomposite ($Fe_3O4@nSiO_2@mSiO_2$) was synthesized and functionalized with trimethylchlorosilane (TMCS). The prepared nanocomposite was used for the removal of diesel oil from aqueous media. The characterization of magnetite-silica nanocomposite was studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscopy (TEM), surface area measurement, and vibrating sample magnetization (VSM). Results have shown that the desired structure was obtained and surface modification was successfully carried out. FTIR analysis has confirmed the presence of TMCS on the surface of magnetite silica nanocomposites. The low- angle XRD pattern of nanocomposites indicated the mesoscopic structure of silica shell. Furthermore, TEM results have shown the core/shell structure with porous silica shell. Adsorption kinetic studies indicated that the nanocomposite was able to remove 80% of the oil contaminant during 2 h and fit well with the pseudo-second order model. Equilibrium studies at room temperature showed that the experimental data fitted well with Freundlich isotherm. The magnetic property of nanocomposite facilitated the separation of solid phase from aqueous solution.

• Journal of Life Science
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• v.21 no.8
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• pp.1183-1189
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• 2011

The present study is aimed at examining the effects of the physico-chemical environmental factors of water systems on water bloom at Homin and Gagok reservoirs in Pungcheon-Myeon, Andong, Gyeongsangbuk-do. The mean water temperature and the contents of chlorophyll-a, total-nitrogen, total-phosphorus and phosphate-phosphorus were higher at the Gagok reservoir. On the other hand, the pH mean value was higher at the Homin reservoir. The mean value of microelements (Na, K, Mg, Fe, Si) was higher at the Gagok reservoir. The cyanobacteria which was considered to be the cause of water bloom at the two reservoirs was Microcystis aeruginosa. It started to grow in May and showed the highest standing crop in August. Between the increase of standing crop of M. aeruginosa and the water quality, correlation values of $Na^+$ (r=-0.910, p<0.05), $Fe^{2+}$ (r=-0.855, p<0.05) and $Si^{4+}$ (r=0.989, p<0.01) at the Homin reservoir increased amount of standing crop. Meanwhile, at the Gagok reservoir, the contents of $Na^+$ (r=-0.776, p<0.05), $Si^{4+}$ (r=0.899, p<0.05) were highly related to the increase of standing crop. Interestingly, Si, which is the limiting factor for diatoms, has a high correlation with standing crop of cyanobacteria. In conclusion, the water blooming is caused not by a simple factor but a synergistic effect due to complex actions including high concentrations of nitrogen and phosphorus ions and many other environmental factors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.596-601
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• 2020

Silicon carbide is considered a potentially useful material for high-temperature electronic devices because of its large band gap energy and p-type or n-type conduction that can be controlled by impurity doping. Accordingly, the thermoelectric properties of -SiC powder prepared by refined diatomite were investigated for high value-added applications of natural diatomite. -SiC powder was synthesized by a carbothermal reduction of the SiO₂ in refined diatomite using carbon black. An acid-treatment process was then performed to eliminate the remaining impurities (Fe, Ca, etc.). n-Type semiconductors were fabricated by sintering the pressed powder at 2000℃ for 1~5h in an N2 atmosphere. The electrical conductivity increased with increasing sintering time, which might be due to an increase in carrier concentration and improvement in grain-to-grain connectivity. The carrier compensation effect caused by the remaining acceptor impurities (Al, etc.) in the obtained -SiC had a deleterious influence on the electrical conductivity. The absolute value of the Seebeck coefficient increased with increasing sintering time, which might be due to a decrease in the stacking fault density accompanied by grain or crystallite growth. On the other hand, the power factor, which reflects the thermoelectric conversion efficiency of the present work, was slightly lower than that of the porous SiC semiconductors fabricated by conventional high-purity -SiC powder, it can be stated that the thermoelectric properties could be improved further by precise control of an acid-treatment process.

• Journal of the Mineralogical Society of Korea
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• v.7 no.2
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• pp.111-127
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• 1994

양남 지역의 제 3 기층인 하서리 응회암층의 중.상부에 부존되는 벤토나이트들은 원암의 암상과 화학조성에 의존되는 광호 양상과 광물상을 나타낸다. 벤톤나이트들은 대부분 안산암질 원암의 기원을 시사하는 희유 및 희토류 원소들의 함유 양상을 보이고, 현무암질 원암의 벤토나이트는 최상부의 일부 층준에만 그 산출이 국한된다. 이 지역의 벤토나이트는 주로 유리질 내지 라필리 응회암이 속성 변질된 것으로 이 과정에서 SiO2와 알칼리 (Na, K) 성분들이 고갈되는 화학 성분상의 유동 양상이 인지된다. 벤토나이트는 주된 광물 성분인 스멕타이트 이외에 흔히 단백석 및 석영같은 규산 광물과 휼란다이트, 모데나이트 및 클리높틸로라이트간은 불석광물들을 수반한다. 스멕타이트는 대부분 몰노릴로나이트 유형이지만 최상부 층준의 현무암질원 벤토나이트와 비교하여 논트로나이트의 광물 화학, X-선회절 양상, 층간 화학 및 염화학적 특성 등이 논의되었다. 이 지역 벤토나이트의 형성과정은 (1) 화산쇄설물의 급속한 퇴적, (2) 비이상적으로 높은 매몰 온도(<8$0^{\circ}C$) 조건, (3) 규산 광물의침전에 의한 공극수 내외 H4SiO4의 제거, (4) 원암의 낮은 Si/al 함유비와 높은 Fe 함유도 등에 의해서 조장된 것으로 해석된다.

• Journal of Ceramic Processing Research
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• v.23 no.5
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• pp.583-588
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• 2022

KTN/BFO multilayer films were manufactured using the spin-coating method on Pt/Ti/SiO2/Si substrate with KTN(62/38) andBFO metal alkoxide solutions. The mean thickness of the multilayer films was about 420-450 nm. A rough interfacial layerwas observed at the interface between the lower substrate and the film when sintered at 650oC. Dense microstructures withoutpores inside of the films were shown via TEM analysis, and an interface between the KTN and BFO layers was clearlyobserved. The Curie temperature was about 16oC. Dielectric constant and dielectric loss were 1380 and 0.384 at 20oC,respectively. Coercive field of the 2-layer and 6-layer films were 72.6 and 80.4 kV/cm at room temperature, respectively. ΔTand EC coefficient of the 6-layer films sintered at 630oC were 1.96oC and 0.13×10-6 oCmV-1, respectively.

• Journal of the Mineralogical Society of Korea
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• v.21 no.1
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• pp.85-98
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• 2008

Calc-silicate rock sheet occurs within the Precambrian metasedimentary rocks in Bonghwa area, Kyungsangbuk-do, Korea. The calc-silicate rock runs parallel to bedding plane with $14{\sim}18$ meters in width. Calcite, dolomite, serpentine and tremolite are occurred as major minerals and talc is occurred as a miner mineral. Serpentine mainly occurs in the upper part and tremolite occurs in lower part of calc-silicate rock sheet. Colors of calc-silicate rock change to deeper green with increasing amounts of serpentine mineral. XRD, FT-IR analyses indicates that serpentine mineral is antigorite. Platy structure of antigorite is well observed by SEM analysis. EPMA data indicates that chemical composition of antigorite is very close to ideal ($SiO_2$: 44.3 wt% and MgO: 40.8 wt%). The chemical formula of antigorite is calculated as $Mg_{2.82}Al_{0.04}Fe^{3+}_{0.04}Si_{2.05}O_5(OH)_4$. From careful study by comparing mineralogical analysis data and occurrence, calc-silicate rock sheet was formed by metamorphism of calcareous sedimentary rocks having different mineralogical and chemical compositions. It is considered that the host rock of serpentine enriched upper part was more Mg-rich rocks than the host rocks of tremolite enriched lower part.

• Journal of the Korean GEO-environmental Society
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• v.11 no.4
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• pp.13-18
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• 2010

The present study was undertaken to investigate the characteristic of suspended matter in soils of Imha-Dam area by turbidity. Soil sampling was conducted at 5 points of Yeongyang (Turbid area) and 2 points of Cheongsong (Clean area). Experimental analysis was conducted using those samples. The pH of water in the soils at turbid area was higher than that of clean area. X-ray diffraction analysis showed that every sample consists in mainly quartz, illite and feldspar before precipitation. After precipitation for 3 days, the content of quartz and feldspar was decreased and the content of illite was increased at turbid area. The soil of Sinheung (St. 6) at clean area was analyzed only illite. SEM-EDS analysis showed the much content of $SiO_2$ as to every sample before precipitation, but $K_2O$, MgO, $Al_2O_3$, CaO and $Fe2O_3$ with illite was increased after precipitation for 3 days as to every sample. Experimental results exhibited that the major mineral of turbid water was illite at turbid area and clean area.