• Journal of the Korean earth science society
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• v.32 no.2
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• pp.170-179
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• 2011

Fly ashes derived from coal fired power plants have unique chemical and mineralogical characteristics. The objective of this research was to study how indigenous bacteria affected heavy metal leaching in fly ash slurry during the fly ash-seawater interactions in the ash pond located in Yeongdong seashore, Korea. The in-situ pH of ash pond seawater was 6.3-8.5. For this study, three sites of the ash pond were chosen to collect a sample of fly ash slurry. Three samples that had a mix of fly ash (0.4 L) and seawater (1.6 L) were collected at each site. First sample was autoclaved ($120^{\circ}C$, 2.5 atm), second one was inoculated with glucose to stimulate the microbial activity, and the last sample was kept in the natural condition. Compared with other samples including autoclaved and natural samples, the glucose added sample showed sharp increase in its alkalinity after 15 days, cation concentration change such as Ca, Mg, and K seemed to increase in early stage, and then decrease 15 days later in slurry solution of glucose added sample, and a possibly considerable decrease in $SO_4^{2-}$ in the fly ash slurry samples when glucose was added to stimulate the microbial activity. Geochemical data of this study is likely to be related to the activity of bacteria at the ash pond. The result may be used to understand about the characteristic of bacteria.

• Horticultural Science & Technology
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• v.34 no.4
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• pp.587-595
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• 2016

Salt stress in crops in reclaimed tidal lands can be reduced by applying soil amendments. To evaluate the effects of compost, gypsum, and phosphate on the growth of Chinese cabbage in saline-sodic soil conditions, we conducted a pot experiment in 2013 and 2014. The treatments consisted of a standard fertilizer application of a mix of compost and N-P-K fertilizer (S) and standard fertilizer applications with additional compost (S + C), gypsum (S + G), phosphate (S+P), and gypsum and phosphate (S + GP). The mean dry matter yield of cabbage in 2014 was three times as great as that in 2013, although soil EC (Electrical conductivity) in 2014 was not decreased. However, the mean ratio of sodium ion in soil solution ($SAR_{1:5}$) significantly decreased from $17.3{\pm}1.1$ in 2013 to $11.2{\pm}2.7$ in 2014. Application of gypsum had the greatest positive impact on the growth of Chinese cabbage. The S + G treatment increased dry matter yield by 7.0 (48.2) and 7.9 g/plant (16.6%) in 2013 and 2014, respectively, compared to the S treatment. Applying gypsum increased soil EC, but decreased $SAR_{1:5}$ by 14 and 38% in 2013 and 2014, respectively. The application of compost and phosphate had a small effect on the growth of Chinese cabbage. These results suggest that applying gypsum in reclaimed tidal lands can reduce the sodicity of the soil and improve crop growth.

• Journal of fish pathology
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• v.23 no.1
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• pp.27-35
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• 2010

Pathogens on the cultured 579 rockfish, Sebastes schlegeli in the marine cage farms from Geoje and Tongyeong of the Southern sea were investigated from 2006 to 2008. The pathogens were detected throughout the year at 46.0~90.0% for 3 years and the detection rate was low with an average 58.1% in May and high with an average 81.5% in October. Bacteria only, bacteria-parasite mix and virus only were found in October and November as well as parasite only, whereas infection of parasite only was dominant in May when the temperature increased and in August when the temperature peaked. Of rockfish, Microcotyle sp. and Caligus sp. were dominant for parasitic disease, and Vibrio sp. and Streptococcus sp. were dominant bacteria. For virus, RSIV and VNNV were detected as dominant organisms. While no virus was detected in 2006, VNNV, VHSV and RSIV were detected in 2007 due to $1.5\sim2.0^{\circ}C$ higher temperature than 2006 in the summer season. For total prevalence by rockfish sizes, the highest was found at 50.0~87.1% in 11~15cm sizes and 50% was found in 30 cm size. Parasite showed a similar trend of 50.0~79.6% as the total prevalence. Prevalence for bacteria varied from 1.6% (for 10 cm group) to 23.8% (for 26 cm group) and higher virus prevalence of 21.5% was found from below 25 cm group.

• Geomechanics and Engineering
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• v.8 no.6
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• pp.859-872
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• 2015

Pebble matrix filtration (PMF) is a water treatment technology that can remove suspended solids in highly turbid surface water during heavy storms. PMF typically uses sand and natural pebbles as filter media. Hand-made clay pebbles (balls) can be used as alternatives to natural pebbles in PMF treatment plants, where natural pebbles are not readily available. Since the high turbidity is a seasonal problem that occurs during heavy rains, the use of newly developed composite clay balls instead of pure clay balls have the advantage of removing other pollutants such as natural organic matter (NOM) during other times. Only the strength properties of composite clay balls are described here as the pollutant removal is beyond the scope of this paper. These new composite clay balls must be able to withstand dead and live loads under dry and saturated conditions in a filter assembly. Absence of a standard ball preparation process and expected strength properties of composite clay balls were the main reasons behind the present study. Five different raw materials from industry wastes: Red Mud (RM), Water Treatment Alum Sludge (S), Shredded Paper (SP), Saw Dust (SD), and Sugar Mulch (SM) were added to common clay brick mix (BM) in different proportions. In an effort to minimize costs, in this study clay balls were fired to $1100^{\circ}C$ at a local brick factory together with their bricks. A comprehensive experimental program was performed to evaluate crushing strength of composite hand-made clay balls, using uniaxial compression test to establish the best material combination on the basis of strength properties for designing sustainable filter media for water treatment plants. Performance at both construction and operating stages were considered by analyzing both strength properties under fully dry conditions and strength degradation after saturation in a water bath. The BM-75% as the main component produced optimum combination in terms of workability and strength. With the material combination of BM-75% and additives-25%, the use of Red Mud and water treatment sludge as additives produced the highest and lowest strength of composite clay balls, with a failure load of 5.4 kN and 1.4 kN respectively. However, this lower value of 1.4 kN is much higher than the effective load on each clay ball of 0.04 kN in a typical filter assembly (safety factor of 35), therefore, can still be used as a suitable filter material for enhanced pollutant removal.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.829-838
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• 2007

The stochiometric mix of evaporating materials for the $CdGa_2Se_4$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CdGa_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $630^{\circ}C$ and $420^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD).The carrier density and mobility of $CdGa_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method are $8.27{\times}10^{17}\;cm^{-3},\;345\;cm^2/V{\cdot}s$ at 293 K. respectively. The temperature dependence of the energy band gap of the $CdGa_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $Eg(T)\;=\;2.6400\;eV\;-\;(7.721{\times}10^{-4}\;eV/K)T^2/(T+399\;K)$. After the as-grown single crystal $CdGa_2Se_4$ thin films were annealed in Cd-, Se-, and Ga -atmospheres, the origin of point defects of single crystal $CdGa_2Se_4$ thin films has been investigated by PL at 10 K. The native defects of $V_{Cd}$, $V_{Se}$, $Cd_{int}$, and $Se_{int}$ obtained by PL measurements were classified as donors or accepters. We concluded that the heat-treatment in the Cd-atmosphere converted single crystal $CdGa_2Se_4$ thin films to an optical p-type. Also, we confirmed that Ga in $CdGa_2Se_4/GaAs$ did not form the native defects because Ga in single crystal $CdGa_2Se_4$ thin films existed in the form of stable bonds.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1C
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• pp.17-25
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• 2012

CLSM (Controlled Low Strength Material) using coal ash, which has the advantages of self-leveling, self-compacting, flowability, easy re-excavation, has been developed. In this study, CLSM additionally mixed with foaming agent for structural backfill material, aimed at lightness of materials, was developed called light-weight foamed CLSM. As the basic study of this material, to determine the optimum final mixing time and dilution ratio of existing light-weight foamed CLSM, flow, slurry unit weight and unconfined compressive strength test according to each impact factor were performed at the standard mix proportion. As the results of tests, CASE N (Final mixing time 4 min, dilution ratio 2%), CASE O (Final mixing time 3 min, foam agents ratio 3%, dilution ratio 2%) were satisfied with the standard of flow test (above 20cm), slurry unit weight test (12~15 $kN/m^3$) and unconfined compressive strength test (800 kPa~1200 kPa). These results will indicate the standard optimum final mixing time and dilution ratio of light-weight foamed CLSM for structural backfill.

• Korean Journal of Agricultural Science
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• v.23 no.1
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• pp.61-69
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• 1996

This study was performed to evaluate the engineering properties of permeable polymer concrete with fillers and unsaturated polyester resin. The following conclusions were drawn. 1. The highest strength was achieved by stone dust filled permeable polymer concrete, it was increased 17% by compressive, 148% by tensile and 188% by bending strength than that of the normal cement concrete, respectively. 2. The static modulus of elasticity was in the range of $1.17{\times}10^5{\sim}1.32{\times}10^5kg/cm^2$, which was approximately 53~56% of that of the normal cement concrete. Stone dust filled permeable polymer concrete was showed relatively higher elastic modulus. The poisson's number of permeable polymer concrete was less than that of the normal cement concrete. 3. The dynamic modulus of elasticity was in the range of $1.3{\times}10^5{\sim}1.5{\times}10^5kg/cm^2$, which was approximately less compared to that of the normal cement concrete. Stone dust filled permeable polymer concrete was showed higher dynamic modulus. The dynamic modulus of elasticity were increased approximately 10~13% than that of the static modulus. 4. The water permeability was in the range of $3.076{\sim}4.390{\ell}/cm^2/h$, and it was largely dependent upon the mix design. These concrete can be used to the structures which need water permeability. 5. The compressive strength, tensile strength, bending strength and elastic modulus were largely showed with the decrease of water permeability.

• 한국해양학회지
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• v.27 no.2
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• pp.154-163
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• 1992

Bacterial abundance, production, and environmental parameters were investigated three times to study distribution of bacterial variables and to examine how estuarine mixing would influence the distribution of bacterial variables in the euphotic zone of the estuarine system of the Mankyung river and Dongjin river during a period of October, 1990-August, 1991. Although a limited number of investigations were made, bacterial abundance and production showed large variations from 0.4 to 5.8${\times}$10/SUP 9/ 1/SUP -1/ and from 0.1 to 22.2 ug C 1/SUP -1/ d/SUP -1/, respectively. The wide ranges of bacterial variables indicated very dynamic changes in conditions of bacterial growth in the estuary. Interestingly, bacterial abundance substantially increased with depth in most stations f shallow depth. but bacterial production remarkably decreased with depth. We propose that the observed distribution of bacterial abundance and production would be explained by estuarine mixing in the estuary. Analyses of mixing diagrams showed that estuarine mixing would mix conservatively bacteria and bacterial production. Further, estuarine mixing often seemed to cause an increase in bacterial abundance and reduction of bacterial production presumably due to resuspension of sediment. This suggests that roles of estuarine mixing would be significant in the distribution of bacterial abundance and production, and thus in biogeochemical cycles in the estuary.

• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.773-780
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• 2011

In this study, thermal stress analysis are carried out considering material properties, curing condition, ambient temperature, and casting date of the mass concrete placed in bottom slab and side wall of the in-ground type LNG tank as a super massive structure. Also, based on the numerical results, cracking possibility is predicted and counter measures to prevent the cracking are proposed. For the tasks, two optimum mix proportions were selected. From the results of the thermal stress analysis, the through crack index of 1.2 was satisfied for separately caste concrete lots except for the bottom slab caste in 2 separate sequences. For the double caste bottom slab, it is necessary introduce counter measures such as pre-cooling prior to the site construction. Also, another crack preventive measure is to lower the initial casting temperature by $25^{\circ}C$ or less to satisfy 1.2 through crack index criterion. In the $1^{st}$ and $2^{nd}$ caste bottom slab, the surface crack index was over 1.2. Therefore, the surface cracks can be controlled by implementing the curing conditions proposed in this study. Since the side wall's surface crack index was over 1.0, it is safe to assume that the counter preventive measures can control width and number of cracks.

• Journal of Korean Society of Forest Science
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• v.102 no.2
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• pp.223-228
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• 2013

Phytoplasmas were detected consistently in 42 mulberry cultivars showing dwarf disease using DNA analysis by amplification with phytoplasma universal primer pairs P1/P7 (about 1.8 kb and R16F2n/R2 (about 1.2 kb). The point mutation from 42 cultivars of mulberry tree was detected by single-strand conformation polymorphism (SSCP) analysis. The SSCP profiles were clearly observed from all of cultivars in 8% polyacrylamide gel, electrophoresizing for and running 8-15 hrs. at 150V, $10^{\circ}C$. The MD and JWB phytoplasma PCR products was mixed and electrophoresis was performed to detect their polymorphism. In this results, the SSCP profiles of all bands of MD and JWB were analyzed on single lane and were distinct in their each of band patterns. The SSCP analysis was possible to detect of 1.8 kb and 1.2 kb nucleotide size and near close band patterns were distinct by mix of two samples. Previously, it was only possible to detect of point mutation under 600 bp nucleotide sequence by SSCP analysis but this modification of SSCP technique was possible to detect clearly SSCP band patterns of about 1.8 kb and 1.2 kb nucleotides.