• Journal of the Korean Ceramic Society
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• v.15 no.4
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• pp.185-192
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• 1978

The effects of slag prticle size, $Na_2SO_4$ addition and sulphide in slag to the foam formation was investigated. This investigation showed that the slag particle size and the amount of $Na_2O$ had produced effects on the size of the foam, foam distribution and firing temperatures. In addition to that the amount of sulphide loss during the firing was controlling factor for the foam formation. The smaller slag particles and higher firing temperatures increased the loss of sulphide in the slag. The addition of $Na_2SO_4$ in the slag batch was likely to inhibit the foam formation. The larger slag particles resutled in the larger foam size and tended to be increasing the batch firing temperature. The main constituents of slag formed glass consisted of wallstonite and glassy phase. It is believed that the controlling the slag particle size and the amount of $Na_2SO_4$ in the slag batch will probably be main factors in foam formation.

• Journal of the Korean Society of Clothing and Textiles
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• v.21 no.4
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• pp.661-668
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• 1997

The dyeing characteristics of acorn was investigated. The natural Fabrics-cotton, rayon and silk-were dyed repeatedly in the solution extracted from acorn, CuSO4, K2Cr2O7 and brine were used as mordants to improve color fastness. Anti-bacterial property was measured in the dyed and mordant treated fabrics. When the cotton and rayon fabrics were dyed and treated with CuSO4, their colors showed very clear. They also had good color fastness and excellent anti-bacterial property. The dyed silk fabrics had better dye absorption property than the cotton and rayon fabrics without mordant treatment. But the fabrics dyed without mordant treatment had low light fastness. The cotton, rayon and silk fabrics dyed and treated with brine were dark and unclear. An aftertreatment with CuSO4 and K2Cr2O7 made the dyed fabrics darter and more clear.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.1
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• pp.49-54
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• 2007

The issue of acid precipitation and related environmental problems in East Asia has been emerging. To evaluate the acidity and chemical characteristics of rainwater in Korea, its chemical properties during cultivation season from April to October in 2005 were investigated at Taean. Also, to estimate the contribution of ions on acidity, ion composition characteristics and neutralization effects by cations were determined. The electrical conductivity balance between measured and estimated values showed a high correlation. Rainwater was highly distributed in the range of pH $4.5{\sim}5.0$. The acidity of rainwater was relatively low during the month of June compared with other monitored periods. $Na^+$ was the main cation, followed by $H^+>Ca^{2+}>NH_4^+>K^+>Mg^{2+}$. Among these ions, $Na^+,\;NH_4^+,\;Ca^{2+}$ and $H^+$ comprised over 94% of the total cations. Rainwater anion composition was more than 80% with $SO_4^{2-}$ and $NO_3^-$. In rainwater samples, $NH_4^+$ and $Ca^{2+}$ contributed greatly to neutralizing the rain acidity. The sulfate content decreased until September, and sea salt derivatives were higher in May and October than during other monitored periods. Also, 78% of the soluble sulfate in rainwater was nss-$SO_4^{2-}$ (non-sea salt sulfate).

• Corrosion Science and Technology
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• v.18 no.6
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• pp.285-291
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• 2019

In this study, the corrosion characteristics of T22 and T92 steel were investigated in 6O₂ + 16CO₂ + 2SO₂ gas environment at 650 ℃. Corrosion characteristics were characterized by weight gain, oxide layer thickness, scanning electron microscope, optical microscope, energy dispersive X-ray spectroscopy, and X-ray diffraction. T22 and T92 steel tended to stagnate oxide layer growth over time. Oxidation kinetics were analyzed using the data of oxide layer thickness, and a regression model was presented. The regression model was significantly acceptable. The corrosion rate between the two steels through the regression model showed significant difference. The T92 steel was approximately twice as large as the time exponent and showed very good corrosion resistance compared to the T22 steel. In both steels, the oxide layer mainly formed a Fe-rich oxide layer composed of hematite (Fe₂O₃), magnetite (Fe₃O₄), and spinel (FeCr₂O₄). Sulfide segregation occurred in the oxide layer due to SO₂ gas. However, the locations of segregation for the T22 and T92 steel were different.

• Journal of environmental and Sanitary engineering
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• v.14 no.1
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• pp.17-23
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• 1999

This study was performed to survey the $SO_2$ level at several underground spaces connected to 5 subway stations (City Hall, Nam, Seoul stations, Hye Hwa and Ulchiro 1 Ga) in Seoul. The period of survey was from July to November, 1997.The results of the study were as follows; 1. The mean concentration of $SO_2$ was $0.057{\pm}0.015ppm$ in all subway stations. The highest $SO_2$ level among the five stations was $0.067{\pm}0.011 ppm$ at City Hall (P<0.01), and the highest with $0.071{\pm}0.013ppm$ at November (P<0.01).2. In underground shopping centers, the mean concentration of $SO_2$ was $0.112{\pm}0.059ppm$. 3. The mean concentration of $SO_2$ at evening with 0.057 pp and morning with 0.053 ppm were significantly higher than at noon with 0.043 ppm(P<0.05). 4. The $SO_2$ level of floor at Kang Nam station with 0.044 ppm was significantly higher than that of platform with 0.37 ppm(P<0.01). 5. For the City Hall stations, the line #1 and line #2 subway spaces show significantly different level of $SO_2$, 0.042ppm and 0.033 ppm respectively (P<0.05).

• The Journal of Engineering Geology
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• v.10 no.3
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• pp.247-261
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• 2000

The geostatistical analyses for the chemical components of pH, TS, KMnO4 Demand, Cl, SO$_4$ and NO$_3$-N are carried out to understand the groundwater contamination in Pusan. The average values of each component are 7.2 for pH, 336.4mg/$\ell$ for TS, 2.3mg/$\ell$ for KMnO$_4$ Demand, 44.3mg/$\ell$ for Cl, 36.0mg/$\ell$ for SO$_4$, and 4.6mg/$\ell$ for NO$_3$-N. The ratios over the drinking standard of each component are 0.34% for pH, 2.27% for TS, 1.55% for KMnO$_4$ Demand, 1.59% for Cl, 0.57% for SO$_4$, and 3.7% for NO$_3$-N. The highest ratio of NO$_3$-N results from the municipal sewage and exhaust gas of vehicles. The isopleth maps of 6 chemical components show that the high values of groundwater contamination come from the inland of Pusan, and that some high values appear at the coastal area. The isopleth maps of Cl and SO$_4$ related with seawater intrusion also show that the high values appear only at the particular coastal area, not at the whole area. On the isopleth maps of Cl and SO$_4$, the anomalies of the concentration contours were compared with the directions of two large fault zones, the Ilkwang Fault and the Dongrae Fault. Apparently, they don't have the particular correlation. Therefore, it is concluded that the main source of groundwater contamination in Pusan is not the seawater, but the municipal sewage and other sources such as the exhaust gas of vehicles, the contaminated surface water, the waste water of factories, and the leachate of waste landfills.

• Journal of the Korean Ceramic Society
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• v.43 no.4 s.287
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• pp.242-246
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• 2006

[ ${\alpha}-Al_2O_3$ ] nanopowders were fabricated by the thermal decomposition and synthetic of Ammonium Aluminum Carbonate Hydroxide (AACH). Crystallite size of 5 to 8 nm were fabricated when reaction temperature of AACH was low, $8^{\circ}C$, and the highest $[NH_4{^+}][AlO(OH)_n{(SO_4){^-}}_{3-n/2}][HCO_3]$ ionic concentration to pH of the Ammonium Hydrogen Carbonate (AHC) aqueous solution was 10. The phase transformation fem $NH_4Al(SO_4)_2$, rhombohedral $(Al_2(SO_4)_3)$, amorphous-, ${\theta}-,\;{\alpha}-Al_2O_3$ was examined at each temperature according to the AACH. A Time-Temperature-Transformation (TTT) diagram for thermal decomposition in air was determined. Homogeneous, spherical nanopowders with a particle size of 70 nm were obtained by firing the 5 to 8 m crystallites, which had been synthesized from AACH at pH 10 and $8^{\circ}C,\;at\;1150^{\circ}C$ for 3 h in air.

• Journal of the Korean Ceramic Society
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• v.38 no.2
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• pp.183-192
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• 2001

산업부산물을 이용하여 3CaO.3Al$_2$O$_3$.CaSO$_4$(C$_4$A$_3$S) 클링커를 합성하였다. 이때, 원료 물질은 산업부산물로 플라이 애쉬, 고로 수쇄 및 괴재슬래그를 $Al_2$O$_3$원으로 그리고 부산석고를 SO$_3$원으로 이용하였으며, CaO원으로 천연석회석을 사용하였다. 제조된 $C_4$A$_3$S 클링커를 CaSO$_4$, CaO를 배합하여 CSA계 팽창재를 제조하였으며, 일반 포틀랜드 시멘트(OPC)에 10 wt.% 첨가하여 수화 및 물성 특성을 조사하였다. 주요 수화생성상은 에트링자이트 및 수산화칼슘이었다. 수화시 에트링자이트의 생성으로 인해 팽창 및 경화체가 치밀화되어 건조수축이 감소되었고, 강도(압출, 인장, 휨)가 향상되었다.

• Environmental Engineering Research
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• v.25 no.1
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• pp.88-95
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• 2020

An investigation of rare metals recovery from LiNi_xCo_yMn_zO₂ cathode material of the end-of-life lithium-ion batteries is presented. To determine the influence of reductant on the leach process, the cathode material (containing Li 7.6%, Co 20.4%, Mn 19.4%, and Ni 19.3%) was leached in H₂SO₄ solutions either with or without H₂O₂. The optimal process parameters with respect to acid concentration, addition dosage of H₂O₂, temperature, and the leaching time were found to be 2.0 M H₂SO₄, 4 vol.% H₂O₂, 70℃, and 150 min, respectively. The yield of metal values in the leach liquor was > 99%. The leach liquor was subsequently treated by precipitation techniques to recover nickel as Ni(C₄H₇N₂O₂)₂ and lithium as Li₂CO₃ with stoichiometric ratios of 2:1 and 1.2:1 of dimethylglyoxime:Ni and Na₂CO₃:Li, respectively. Cobalt was recovered by solvent extraction following a 3-stage process using Na-Cyanex 272 at pH_eq ~5.0 with an organic-to-aqueous phase ratio (O/A) of 2/3. The loaded organic phase was stripped with 2.0 M H₂SO₄ at an O/A ratio of 8/1 to yield a solution of 114 g/L CoSO₄; finally recovered CoSO₄.xH₂O by crystallization. The process economics were analyzed and found to be viable with a margin of $476 per ton of the cathode material.

• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.351-356
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• 2007

The crystal structure of $Li(ND_4)SO_4$ was analyzed by X-ray and neutron diffraction methods. The crystal is a deuterated $Li(NH_4)SO_4$ and one of the ferroelectric materials with hydrogen atoms. The crystal is orthorhombic at room temperature, $P2_1nb$, with lattice parameters of $a=5.2773(5)\;{\AA},\;b=9.1244(23)\;{\AA},\;c=8.7719(11)\;{\AA}$ and Z=4. Neutron intensity data were collected on the Four-Circle diffractometer (FCD) at HANARO in Korea Atomic Energy Research Institute and X-ray date were given by Prof. Y. Noda of Tohoku University Japan. The structure was refined by full-matrix least-square to final R value of 0.070 for 1450 observed reflections by X-ray diffraction and to final R=0.049 for 745 observed reflections by neutron diffraction. With X-ray data we obtained only one hydrogen atomic position. However, not only all atomic positions of four hydrogen atoms at $NH_4$ but also the occupation factors of D and H were refined with neutron data. From this results we obtained the average chemical structure of this sample, $LiND_{3.05}H_{0.95}SO_4$.