• Korean Journal of Soil Science and Fertilizer
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• v.18 no.3
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• pp.282-288
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• 1985

This experiment was conducted to investigate the changing patterns of the available elements by the control of lime addition amount and temperature in Acid Sulfate Soils under the submerged condition. The results obtained were summarized as follows: 1. pH and contents of available phosphate, soluble silicate, $NH_4-N$, and exchangeable iron in soils were decreased but exchangeable aluminium and manganese, and water soluble sulfur in soils increased after submergence. 2. Lime treatment increased pH, available phosphate, soluble silicate, $NH_4-N$, and water soluble sulfur, but that decreased exchangeable aluminium, iron, and manganese in soils. 3. Treatment with 12me/100gr of Ca as $CaCO_3$, showed the marked effect in increasing the exchangeable aluminium and iron, and increasing pH value to about 6.5 as well as available phosphate and $NH_4-N$. 4. Increases in available phosphate, $NH_4-N$, and exchangeable iron with aging of the soil flooded and lime treated were higher at $35^{\circ}C$ than those at $25^{\circ}C$. 5. Throughout submerged period a significant positive correlation was observed between pH and soluble silicate while the pH has negative correlation with exchangeable elements such as aluminium, iron, and manganese etc.

• Applied Biological Chemistry
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• v.22 no.4
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• pp.191-197
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• 1979

${\beta}-Tyrosinase$ was purified and crystallized from cells of Escherichia intermedia A-21 grown in a medium supplemented with 0.2% L-tyrosine. Molecular weight of its subunit, Km value and absorption spectra were determined. Crystallization methods were also studied to eliminate any unnecessary procedures. The results obtained were as follows: 1. The purification procedure included ammonium sulfate fractionation, dialysis against potassium phosphate buffer, pH 6.0 and pH 7.0, and DEAE-Sephadex column chromatography. In the column chromatography, 11 mg of protein was applied per ml of DEAE-Sephadex for efficiency. 2. Steps of protamine sulfate treatment and Sephadex G-150 gel filtration could be eliminated for this enzyme from the known procedures. 3. The purified enzyme was dissolved in 0.01M potassium phosphate buffer containing 2-mercaptoethanol, with a concentration of 20mg/ml. Crystalline enzyme, which appears as hexagonal rods, was obtained by adding solid fine powdered ammonium sulfate to the enzyme solution. 4. Absorption maxima of the enzyme appeared at 340 and 430nm when associated with pyridoxal phosphate. 5. Km value of the enzyme for L-tyrosine was $2.31{\times}10^{-4}M$ and the molecular weight of its subunit was determined by SDS-polyacrylamide electrophoresis to be approximately 50,000.

• Journal of the Korean Geotechnical Society
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• v.23 no.12
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• pp.25-32
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• 2007

This study is to evaluate the effect of chemical attack on durability and deterioration of lining concrete in tunnel. Surface examination, nondestructive inspection, uniaxial compressive strength test, carbonation test, chloride diffusion test, micro-structural analysis were performed to analyze the deterioration of lining concrete in tunnel constructed 70 years ago. From surface examination results, the tunnel had been repaired and reinforced in several times. It has many cracks, water-leakage, efflorescence and exploitation. Compressive strengths obtained from nondestructive inspection and uniaxial compressive strength test have measured $17.5{\sim}34.7MPa$, and $12.8{\sim}40.3MPa$, respectively. Carbonation depth specimen cored from concrete lining has ranged from 3mm to 27mm. From chloride diffusion test, most specimens have low permeability. And the XRD analysis was able to detect ettringite and thaumasite, which were confirmed by SEM and EDS results to be the causes for the deterioration of lining concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.12-23
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• 2024

In this study, a structural concrete square beam was developed using the centrifugal molding technique. In order to secure the bending stiffness of the cross section, the hollow rate of the cross section was set to 10% or less. Instead of using the current poor mixture of concrete and a concrete mixing ratio with a high slump (150-200) and a design strength of 100 MPa or more was developed and applied. In order to investigate the durability of centrifugally formed PSC square beams to be used as the superstructure of the avalanch tunnel or ramen bridge, the durability performance of ultra-high-strength centrifugally formed concrete with a compressive strength of 100 MPa was evaluated in terms of deterioration and chemical resistance properties.Concrete durability tests, including chloride penetration resistance, accelerated carbonation, sulfate erosion resistance, freeze-thaw resistance, and scaling resistance, were performed on centrifugally formed square beam test specimens produced in 2022 and 2023. Considering the information verified in this study, the durability of centrifugally molded concrete, which has increased watertightness in the later manufacturing stage, was found to be superior to that of general concrete.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.651-660
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• 2007

Acid drainage has been recognized as an environmental concern in abandoned mine sites for long time. Recently, the environmental and structural damage by acid drainage is a current issue in construction sites in Korea. Here, the author introduces the type of damages by acid drainage in construction sites and emphasizes the importance of geoscience discipline in solving the problem. Metasedimentary rock of Okcheon group, coal bed of Pyeongan group, Mesozoic volcanic rock. and Tertiary sedimentary and volcanic rocks are the major rock types with a high potential for acid drainage upon excavation in Korea. The acid drainage causes the acidification and heavy metal contamination of soil, surface water and groundwater, the reduction of slope stability, the corrosion of slope structure, the damage on plant growth, the damage on landscape and the deterioration of concrete and asphalt pavement. The countermeasure for acid drainage is the treatment of acid drainage and the prevention of acid drainage. The treatment of acid drainage can be classified into active and passive treatments depending on the degree of natural process in the treatment. Removal of oxidants, reduction of oxidant generation and encapsulation of sulfide are employed for the prevention of acid drainage generation.

• Economic and Environmental Geology
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• v.49 no.1
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• pp.13-22
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• 2016

The objectives of this study were to recover silica and iron oxides and $CO_2$ sequestration using serpentine via various acid dissolution and pH swing processes. Serpentine collected from Guhang-myeon in S. Korea were mainly composed of antigorite and magnetite consisting of $SiO_2$ (45.3 wt.%), MgO (41.3 wt.%), $Fe_2O_3$ (12.2 wt.%). Serpentine pulverized ($${\leq_-}75{\mu}m$$) and then dissolved in 3 different acids, HCl, $H_2SO_4$, $HNO_3$. Residues treated with acidic solution were recovered from the solution (step 1). And then the residual solution containing dissolved serpentine was titrated using $NH_4OH$. And pH of the solution increased up to pH=8.6 to obtain reddish precipitates (step 2). After recovery of the precipitates, the residual solution reacted with $CO_2$ and then pH increased up to pH=9.5 to precipitate white materials (step 3). The mineralogical characteristics of the original sample and harvested precipitates were examined by XRD, and TEM-EDS analyses. ICP-AES analysis was also used to investigate solution chemistry. The dissolved ions were Mg, Si, and Fe. The antigorite became noncrystralline silica after acid treatment (step 1). The precipitate at pH=8.6 was mainly amorphous iron oxide, of which size ranged from 2 to 10 nm and mainly consisting of Fe, O, and Si (step 2). At pH=9.5, nesquehonite [$Mg(HCO_3)(OH){\cdot}2(H_2O)$] and lasfordite [$MgCO_3{\cdot}H_2O$] were formed after reaction with $CO_2$ (step 3). The size of carbonated minerals was ranged from 1 to $6{\mu}m$. These results indicated that the acid treatment of serpentine and pH swing processes for the serpentine can be used for synthesis of other materials such as silica, iron oxides and magnesium carbonate. Also, This process may be useful for the precursor synthesis and $CO_2$ sequestration via mineral carbonation.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.635-649
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• 2007

Geochemical composition, stable isotopes $({\delta}^{18}O,\;{\delta}D,\;{\delta}^{34}S)$ and noble gases(He, Ne and Ar) of nine hot spring water and three groundwater for five hot springs(Jukam, Hwasun, Dokog, Jirisan, Beunsan) from the Honam area were analyzed to investigate the hydrogeochemical characteristics and the hydrogeochemical evolution of the hot spring waters, and to interpret the source of sulfur, helium and argon dissolved in the hot spring waters. The hot spring waters show low water temperature ranging from 23.0 to $30.5^{\circ}C$ and alkaline characteristics of pH 7.67 to 9.98. Electrical conductivity of hot spring waters is $153{\sim}746{\mu}S/cm$. Groundwaters in this area were characterized by the acidic to neutral pH range$(5.85{\sim}7.21)$, the wide electrical conductivity range $(44{\sim}165{\mu}S/cm)$. The geochemical compositions of hot spring and groundwaters can be divided into three water types: (1) $Na-HCO_3$ water type, (2) Na-Cl water type and (3) $Ca-HCO_3$ water type. The hot spring water of $Ca-HCO_3$ water type in early stage have been evolved through $Ca(Na)-HCO_3$ water type into $Na-HCO_3$ type in final stage. In particular, Jurim alkaline(pH 9.98) hot spring water plotted at the end point of $Na-HCO_3$ type in the Piper diagram is likely to arrive into the final stage in geochemical evolution process. Hydrogen and oxygen isotopic data of the hot spring water samples indicate that the hot spring waters originated from the local meteoric water showing latitude and altitude effects. The ${\delta}^{34}S$ value for sulfate of the hot spring waters varies widely from 0.5 to $25.9%o$. The sulfur source of most hot spring waters in this area is igneous origin. However, The ${\delta}^{34}S$ also indicates the sulfur of JR1 hot water is originated from marine sulfur which might be derived ken ancient seawater sulfates. The $^3He/^4He\;and\;^4He/^{20}Ne$ ratios of the hot spring waters range from $0.0143{\times}10^{-6}\;to\;0.407{\times}10^{-6}\;and\;6.49{\sim}584{\times}10^{-6}$, respectively. The hot spring waters are plotted on the mixing line between air and crustal components. It means that the He gas in the hot spring waters was mainly originated from crustal sources. However, the JR1 hot spring water show a little mixing ratio of the helium gas of mantle source. The $^{40}Ar/^{36}Ar$ ratios of hot spring water are in the range from $292.3{\times}10^{-6}\;to\;304.1{\times}10^{-6}$, implying the atmospheric argon source.

• Microbiology and Biotechnology Letters
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• v.3 no.3
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• pp.123-134
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• 1975

Out of 96 yeast strains isolated from various natural habitats, five strains were screened based on their ability to ferment agricultural biproducts such as rice-, barley-and wheat-bran, and sawdust. These were identified as Hansenula anomala var anomala, Candide utilis, C. pelliculosa, Debaryomyces hansenii, and Irpex lacteus. Using these yeasts the above mentioned agricultural biproducts were fermented in various combinations. The fermented product was fed to 180 male Starcroses for eight weeks and obtained a body weight increase of 15.1g a day, while the unfermented control feed increased 10.5g a day.