• Journal of the Korea Concrete Institute
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• v.20 no.4
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• pp.439-449
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• 2008

Mineral admixtures are used to improve the quality of concrete and to develop sustainability of concrete structures. Supplementary cementitious materials (SCM), such as silica fume (SF), granulated blast furnace slag (GGBS) and pulverized fly ash (PFA), are gradually recognized as useful mineral admixture for producing high performance concrete. The study on ternary blended concrete utilizing mainly three major mineral admixtures is limited and the study on durability and chloride induced corrosion resistance of ternary blended concrete is very few. This study examines the durability characteristics of the ternary blended concrete composed of different amount of the SCM with ordinary Portland concrete and the study experimentally focuses on corrosion resistance evaluation of ternary blended concrete subjected to chloride attack. In this study, 50% replacement ratio of mineral admixture to OPC was used, while series of combination of $20{\sim}40%$ GGBS, $5{\sim}15%$ SF and $10{\sim}45%$ PFA binder were used for chloride corrosion resistance test. This study concerned the durability properties of the ternary blended concrete including the corrosion resistance, chloride binding, chloride transport and acid neutralization capacity. It was found that the ternary blended concrete utilizing the SCM densified the pore structures to lower the rate of chloride transport. Also, increased chloride binding and buffering to acid were observed for the ternary blended concrete with chlorides in cast.

• Journal of Plant Biology
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• v.25 no.3
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• pp.135-151
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• 1982

This investigation was carried out to clarify the changes of pigments and soluble protein, and photosystem II activity in the leaves of barley (${SO}_2$-sensitive) and corn (${SO}_2$-resistant) seedlings induced by the ${SO}_2$ fumigation (10, 50ppm). The pH changes of the leaf extract, the content of sulfite and sulfate, the activities of catalase, peroxidase, and polyphenoloxidase were compared in the leaves of barley and corn seedlings induced by ${SO}_2$ fumigation. The results are summarized as follows: An appreciable effect of pH change of leaf extract by ${SO}_2$ fumigation was observed in barley leaves (pH 6.10 to 5.18), but only a small change occurred in corn leaves (pH 5.66 to 5.50). The same pattern of pH changes was recorded when the solution of 0.2N HCl was added to leaf extract, providing lower buffering capacity of the barley leaves than corn leaves. After 2 hours of exposure to 10 ppm ${SO}_2$, the contents of ${SO}^{2-}_3$ and ${SO}^{2-}_4$ were increased in barley leaves, while only ${SO}^{2-}_4$ increased in corn leaves. After fumigation with 10ppm ${SO}_2$ for 2 hours, barley leaves showed significant decreases in activities of catalase, to 17% peroxidase, to 58%, and polyphenoloxidase, to 88%. Corn leaves showed increases in activities of peroxidase, to 136%, and polyphenoloxidase, to 128%. Absorption spectra of pigments obtained from ${SO}_2$-fumigated leaves were gradually decreased with the fumigation time increases, but the decrease was more significant in barley leaves. Fumigation with 50ppm ${SO}_2$ for 2 hours induced the greatest decomposition in carotenoid, followed by chlorophyll a and then chlorophyll b in barley leaves. The ratio of chlorophyll a/b was decreased from 4.1 to 3.6 in barley leaves, but in corn leaves it was maintained almost a constant level(4.9-4.8). The rate of decomposition of chlorophyll and carotenoid in corn leaves was very slow than those in the barley leaves. Fumigation with 50 ppm ${SO}_2$ for 2 hous, decreased the protein content of barley leaves to 59%, and that of corn leaves to 89%, and the extent of decrease in protein content was greater than that of pigments in barley and corn leaves. The rate of DCIP9dichlorophenol indophenol) photoreduction in ${SO}_2$-fumigated leaves was decreased to 18 and 67% in barley and corn leaves, respectively. However, DCIP photoreduction was considerably recovered about 32 and 92% with the addition of DPC(diphenylcarbazide) as an exogenous electron donor in barley and corn leaves, respectively.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.617-623
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• 2004

Acidic drink has been known as a cause of tooth erosion. The purpose of this study is to verify the acid levels of orange juices in market and evaluate the erosion effects on the enamel of deciduous teeth by orange juices in relatively short period of time. With four kinds of orange juice selected from market, pH, buffering capacity and concentration of Ca and P ion were measured. And forty segments of normal enamel of deciduous incisors were divided into four groups and level of erosion was measured by surface hardness test before and after soaking at 50ml of orange juice for 10 minutes. The results of this study showed that the average pH of orange juices was 4.0 and this pH value was so acidic as to cause the tooth erosion. There were differences in small quantity for each group of teeth, however, the result was statistically so significant that orange juices can cause enamel erosion in relatively short period of time.

• The Journal of Engineering Geology
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• v.12 no.4
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• pp.471-484
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• 2002

Alluviums in the Keum River watershed cover an areal extent of $3,029{\;}\textrm{km}^2$ and contain about 8.1 billion tons of groundwater. However, the waters are severely polluted by nitrate, possibly due to the application of nitrogen fertilizer (>250 N kg/ha) on agricultural land. This paper aims to elucidate the pollution status and behaviors of nitrate in alluvial groundwaters in the Keum River watershed area, based on regional hydrogeochemical study. Most of the collected samples (n = 186) are polluted by nitrate (average = 42.2 mg/L, maximum = 295 mg/L). About 29% of the samples have the nitrate concentrations exceeding Korean Drinking Water Standard (44 mg/L $NO_3$). The distribution of nitrate concentrations in the study area is largely dependant on geochemical environments of alluvial aquifers. In particular, the decrease of redox potential of alluvial groundwaters showed a good correlation with the decreases of nitrate, iron, and manganese concentrations. Thus, the change of redox state in alluvial aquifers, likely reflecting their sedimentary environments, controls both the behavior and fate of nitrogen compounds and their natural attenuation (denitrification) in aquifers. A carbon-rich, silty layer within alluvium strata forms a reducing condition and possesses a buffering capacity on nitrate pollution.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.6
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• pp.335-343
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• 2002

Methods of bedsoil analysis were difficult to be applied universally because use and material of bedsoil are diverse from country to country. Korean Standard Methods for Bedsoil Analysis was developed to measure the water content, water retention, and saturated hydraulic conductivity. Fifty-three samples for horticultural bedsoil and nine samples for paddy rice bedsoil in the current market were collected. Water content of bedsoil was determined using gravimetric method through $105^{\circ}C$ oven-dry for 16 hours, but different calculations between horticultural and paddy rice bedsoils were chosen according to different predominant component, plant residue or mineral. Water content percentage of horticultural bedsoil was calculated as [(weight of sample before oven-dry - weight of sample after oven-dry)/(weight of sample before oven-dry)]${\times}100$, while that of paddy rice bedsoil as [(weight of sample before oven-dry - weight of sample after oven-dry)/(weight of sample after oven-dry)]${\times}100$. Water retention was measured at water potential -0.5, -1, -3, -5, -7, -10 kPa by Sandbox method and saturated hydraulic conductivity was measured by constant head method using acryl cylinder (${\Phi}5cm{\times}L\;20cm$). By new 'Korean Standard Methods of Bedsoil Analysis', the average water content of horticultural bedsoil was obtained 46.34%(w/w) and that of paddy rice bedsoil 16.89%. For horticultural bedsoil, easily available water(EAW), water buffering capacity(WBC), and optimal matric potential(OMP) was estimated at 28.4%, 7.01%, and -5.60 kPa, respectively. Optimal moisture content was 44.41% and average saturated hydraulic conductivity for bedsoils was estimated at $28.4cm\;min^{-1}$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.6
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• pp.888-895
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• 2015

For effective utilization of butter clam shell as a natural calcium resource, the optimal conditions for preparation of calcium acetate (BCCA) with high solubility were determined using response surface methodology (RSM). The polynomial models developed by RSM for pH, solubility, and yield were highly effective in describing the relationships between factors (P<0.05). Increased molar ratio of calcined powder (BCCP) from butter clam shell led to reduction of solubility, yield, color values, and overall quality. Critical values of multiple response optimization to independent variables were 2.70 M and 1.05 M for acetic acid and BCCP, respectively. The actual values (pH 7.04, 93.0% for solubility and 267.5% for yield) under optimization conditions were similar to predicted values. White indices of BCCAs were in the range of 89.7~93.3. Therefore, color value was improved by calcination and organic acid treatment. Buffering capacity of BCCAs was strong at pH 4.88 to 4.92 upon addition of ~2 mL of 1 N HCl. Calcium content and solubility of BCCAs were 20.7~22.8 g/100 g and 97.2~99.6%, respectively. The patterns of fourier transform infrared spectrometer and X-ray diffractometer analyses from BCCA were identified as calcium acetate monohydrate, and microstructure by field emission scanning electron microscope showed an irregular form.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.392-399
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• 2007

This study was carried out to assess optimum conditions of peatmoss-based substrates for red pepper plug seedlings. Peatmoss-based substrates prepared by mixing of peatmoss with vermiculite, perlite, rice hull and zeolite at various mixing ratios were used for growing pepper plug seedlings. The physical and chemical properties of the peatmoss substrate were analyzed by the CEN(European committee for standardization) method. Fresh and dry weights (shoot, root), leaf area, root length and T/R ratio (dry shoot weight/dry root weight) were determined at 55 days after sowing. The results showed that the growing media PVSZ 6 (peatmoss:silver vermiculite: zeolite=6:3.9:0.1) and PVGZ 6 (peatmoss:gold vermiculite: zeolite=6:3.9:0.1) can successfully be used for red pepper plug seedlings judging from dry weight and T/R ratio of the plug seedlings. The optimal ranges of total pore space, water volume, air volume, easily available water content and water buffering capacity of the peatmoss based growing media for pepper plug seedlings were 87~93%, 52~71%, 20~41%, 10~37% and 0.6~10%, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.369-376
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• 2007

This experiment was carried out to investigate optimum conditions of coir-based substrates for the red pepper plug seedlings. Eleven different coir based substrates prepared by mixing of coir, vermiculite, rice hull, perlite, zeolite, mixed at different ratios were tested. The physical and chemical properties of the substrates were analyzed by the CEN (European committee for standardization) method. Fresh and dry weights of shoot and root, leaf area, root length, and T/R ratio (dry shoot weight/dry root weight) were determined at 55 days after sowing. The results showed that the growing media CRZ 8(coir:rice hull: vermiculite=8:1.9:0.1) and CVSZ 6(coir:silver vermiculite: zeolite=6:3.9:0.1) can successfully be used for pepper plug seedlings judging from dry weight and T/R ratio of the plug seedlings. The optimal range of total pore space, water volume, air volume, easily available water content and water buffering capacity of the coir-based growing substrates for pepper plug seedlings were in the range of 92~94%, 52~60%, 32~43%, 18~21%, and 0.9~8%, respectively.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.515-532
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• 2023

Bentonite, predominantly consists of expandable clay minerals, is considered to be the suitable buffering material in high-level radioactive waste disposal repository due to its large swelling property and low permeability. Additionally, the bentonite has large cation exchange capacity and specific surface area, and thus, it effectively retards the transport of leaked radionuclides to surrounding environments. This study aims to review the thermodynamic sorption models for four radionuclides (U, Am, Se, and Eu) and eight bentonites. Then, the thermodynamic sorption models and optimized sorption parameters were precisely analyzed by considering the experimental conditions in previous study. Here, the optimized sorption parameters showed that thermodynamic sorption models were related to experimental conditions such as types and concentrations of radionuclides, ionic strength, major competing cation, temperature, solid-to-liquid ratio, carbonate species, and mineralogical properties of bentonite. These results implied that the thermodynamic sorption models suggested by the optimization at specific experimental conditions had large uncertainty for application to various environmental conditions.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.157-164
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• 2014

Objective of this research was to develop root media containing expanded rice hull (ERH) and carbonized rice hull (CRH). To achieve this, the physico chemical properties of two materials were analysed and blended with peatmoss (PM) or coir dust (CD) with various ratio. Based on the physical properties of the blended materials, 4 root media were selected for future experiment. After the analysis of pH and EC of the selected root media, the kinds and amount of pre-planting nutrient charge fertilizers (PNCF) incorporated into each root medium were varied, and then, final chemical properties of the root media were analysed. The total porosity (TP), container capacity (CC), and air-filled porosity (AFP) were 81.3%. 39.9%, and 41.4% in ERH and 77.6%, 64.1%, and 13.5% in CRH, respectively. The percentage of easily available water (EAW, from CC to 4.90 kPa tension) and buffering water (BW, 4.91-9.81 kPa tension) were 11.37% and 5.27%, in ERH and 17.26% and 14.28% in CRH, respectively. The pH of ERH was 7.1, but it was extremely high in CRH such as 11.2. The EC and CEC were $1.31dS{\cdot}m^{-1}$ and $12.1meq{\cdot}100g^{-1}$ in ERH and $6.53dS{\cdot}m^{-1}$ and CEC 7.79 $meq{\cdot}100g^{-1}$ in CRH, respectively. The ranges of TP, CC and AFP in 4 selected media (PM + ERH, 6:4, v/v; CD + ERH, 8:2; PM + CRH, 7:3; CD+CRH 6:4) were 89.2-90.3%, 67.3-81.8%, and 8.3-21.9%, respectively. The pHs and ECs in root media containing peatmoss such as PM + ERH (6:4) and PM + CRH (7:3) were 4.0-4.3 and $0.33-0.365dS{\cdot}m^{-1}$, whereas those of CD + CRH were 7.4-7.9 and $1.282dS{\cdot}m^{-1}$. The pHs and ECs, however, analysed before and after the incorporation of PNCF in each root medium were not significant different. This result indicated that the incorporated fertilizers in PNCF to adjust medium pH did not dissolve enough to influence medium pH, but it is very normal in root media containing dolomitic lime and sulfur powder in adjusting pH. The Information obtained in this study may facilitate an effective formulation of root media containing rice hulls.