• Land and Housing Review
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• v.14 no.1
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• pp.83-97
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• 2023

The study aims to provide an academic basis for the preservation and restoration of abandoned paddy wetland and the enhancement of its carbon accumulation function. First, the temporal change of the wetlands was analysed, and a typological classification system for wetlands was attempted with the goal of carbon reduction. The types of wetland were classified based on three variables: hydrological environment, vegetation, and carbon accumulation, with a special attention on the function of carbon accumulation. The types of abandoned paddy wetlands were classified into 12 categories based on hydrologic variables- either high or low levels of water inflow potential-, vegetation variables with either dominance of aquatic plants or terrestrial plants, and three carbon accumulation variables including organic matter production, soil organic carbon accumulation, and decomposition. It was found that the development period of abandoned paddy analyzed with aerial photographs provided by the National Geographic Information Institute happened between 2010 and 2015. In the case of the wetland in Daejeon 1 (DJMN01) farming stopped by 1990 and it appeared to be a similar structure to natural wetlands after 2010 . Over the past 40 years the abandoned paddy wetland changed to a high proportion of forests and agricultural lands. As time went by, such forests and agricultural lands tended to decrease rapidly and the lands were covered by artificial grass and other types of forests.

• The Journal of Engineering Geology
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• v.33 no.1
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• pp.51-59
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• 2023

The Nakdong river is both a natural resource crucial to underwater ecosystems and a water source for its basin's residents. Industrial wastewater and domestic sewage must meet the relevant standards for discharged water before they can flow into the river. The correlation between old and new measures of organic matter was examined using water quality data from 50 monitoring locations in the main stream of the Nakdong river. The coefficient of determination (R²) for total organic carbon (TOC), the new measure of organic matter, and chemical oxygen demand (COD), the old measure of organic matter, in the main stream of the Nakdong river was 0.6134, indicating high correlation. Water quality at each location assessed using TOC and COD showed disparities that cannot be ignored: quality appeared higher when evaluating the main stream of the Nakdong river using TOC instead of COD. Therefore, there remains a need to review water quality ratings based on TOC; continuous monitoring of COD is also required. In addition, the cause of the difference should be clearly identified to help assess artificial sources of pollution and natural factors affecting organic matter. Water management of the Nakdong river will then be possible using the water quality rating.

• Journal of the Korea Convergence Society
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• v.13 no.1
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• pp.149-160
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• 2022

In this study, the physical quality and microbial changes of ginseng sprout according to the pretreatment process and packaging container were evaluated to improve the storage properties of ginseng sprout produced in smart farm. Quality change during storage (10 days) according to pretreatment method (ascorbic acid, citric acid, peroxyacetic acid) and packaging container (expanded polystyrene (EP), polypropylene (PP), polyethylene (PE), polypropylene + polyethylene + cast polypropylene (PP+PE+CPP)) was evaluated in terms of texture, viable cell count, water content, and color. As a result of comparison according to the type of pretreatment, the citric acid treatment group showed the lowest texture change and the effect on inhibition of bacterial growth. On the other hand, citric acid, which was most effective among pretreatments, was treated in all samples and then stored in 4 types of containers. Specially, the ginseng sprout in PP packaging container was not observed significant softening or color changes after 10 days storage, and the lowest changes in viable cell number. Therefore, this study was shown that citric acid treatment and use of PP packaging container are effective in increasing the shelf life of ginseng sprout.

• Korean Journal of Organic Agriculture
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• v.31 no.4
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• pp.395-412
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• 2023

The morphology and whole genome sequence of Hyphantria cunea nucleopolyhedrovirus W1 (HycuNPV-W1) isolated in Korea were analyzed for the use as an eco-friendly control agent against H. cunea. The HycuNPV-W1 had irregular tetrahedral polyhedra with a size of 1.5-2.2 ㎛ which is similar to that of previously reported HycuNPV isolated in Korea. As a result of whole viral genome analysis, HycuNPV-W1 was composed of 131,353 bp, which is 1,606 bp shorter than that of the previously reported HycuNPV. The G+C content was 45% and six of the homologous repeated regions were found, so there was no significant difference from the previous report. As a result of ORF analysis, HycuNPV-W1 contains total of 145 ORFs which is three ORFs less than the previous report, while two ORFs were exclusively found in HycuNPV-W1. The functions of these ORFs remains unclear and are not considered to have a significant influence on the characteristics of the HycuNPV. The genome vista analysis showed that the overall sequence identity between HycuNPV-W1 and the previously reported HycuNPV was very high. The whole genome of HycuNPV-W1 analyzed was found to be similar to those of the previously reported HycuNPV, however, it is supposed to be a novel resource in Korea with different isolate.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.4
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• pp.112-121
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• 2009

To obtain basic design criteria for underground anaerobic digestion and enhance biogas production from swine slurry, a $20m^3$ underground anaerobic digester (UGAD) was constructed and operated at mesophilic ($31{\sim}37^{\circ}C$) temperature with an organic loading rate (OLR) at $23.6kgVS/m^3/day$. The average biogas and $CH_4$ production rate were observed at 8.62 and $5.78m^3/day$, respectively. The mean percentile of $CH_4$ and $CO_2$ were also observed at 67.5% and 19.6%. The relative biogas yield was explored at $733L/kg\;VS_{added}$ and $CH_4$ yield was at $495L/kg\;VS_{added}$ respectively. The removal rate of biochemical constituents and pathogens were noticed considerably at 68%, 74%, 79%, 86%, 89%, 81%, 55%, 79%, 98% and 100% on TS, VS, TSS, $BOD_5$, $TCOD_{cr}$, $SCOD_{cr}$, $NH_3-N$, available P, fecal coliforms and Salmonella, respectively. This study suggested that, the modified UGAD system is a greatly desirable for anaerobic digestion for swine slurry with regards to high methane yield and biodegradability.

• Economic and Environmental Geology
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• v.47 no.4
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• pp.381-393
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• 2014

Seismic reflection data are integrated with fieldwork data in order to understand startigraphy, structural geology and hydrocarbon potentials of Cretaceous strata in the Mesopotamian basin, Northeastern Iraq. Cretaceous strata in the basin divided into the Qamchuqa, Kometan, Bekhme and Shiranish formations, which are composed of carbonates deposited in shallow marine environment. The geological structures in these formations are mainly recognized as thrusts, detachment folds, fault propagation folds and fault bend folds. As well, NW-SE trending fractures are regularly developed, and are horizontal or perpendicular to the structures. The distribution and frequency of fractures are related to the development of the thrusts. In terms of hydrocarbon potentials, Cretaceous strata in the basin have limited capacities for source rocks and seal rocks due to the lack of organic carbon content and the well-developed fractures, respectively. Although these carbonates have limited primary porosity, however, development of the secondary porosity derived from the fractures contributes to enhance the reservoir quality. Most important factor for the reservoir quality of Cretaceous strata seems to be the frequency and connectivity of fractures relative to locations of folds and faults. The results delineated in this study will use as reference for recognizing stratigraphy and structures of Cretaceous strata and will provide useful information on hydrocarbon potentials of Cretaceous strata in the Mesopotamian basin, NE Iraq.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.329-338
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• 2013

The objective of this study is to investigate the contents and seasonal variation of arsenic in soils and crop plant(rice) in paddy fields around the abandoned metal mines in Korea. The soils were extracted by various methods including aqua regia, 1 M $MgCl_2$, 0.01 M $CaCl_2$ and 0.05 M EDTA to evaluate the relationships between soils and crop plants(rice). According to correlation analysis, statistically significant correlation with the four methods(p<0.01) were found in soils extracted by various chemical solutions and arsenic contents in soils were decreased in the order of 1M $MgCl_2$ > 0.01M $CaCl_2$ > 0.05 M EDTA. Biological accumulation coefficients(BACs) of rice stalks were higher than those of rice grain, and the coefficients under reducing(August) environment were higher than those under oxidizing conditions(October). Assuming the rice consumption of 315 g/day by farm households in Korea, the amount of daily intake of arsenic were estimated to be 77.8 ${\mu}g/day$. The daily intake of arsenic from the rice estimates up to 65% of ADI(acceptable daily intake) that the FAO/WHO Joint Food Additive and Contaminants Committee has set to evaluate their safeties.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.2
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• pp.136-143
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• 2013

In the sewage structures and wastewater facilities, concrete is exposed to hydrogen sulfide ($H_2S$) which acts as an acid material in a solution, and a strongly acidic sulfate ion ($SO{_4}^{-2}$) is generated by a sulfuric bacteria. Hence, a degradation of concrete with biochemical corrosion would be accelerated. Finally, durability of concrete and concrete structures may be greatly reduced. In this study, in order to remove the hydrogen sulfide which is used by the sulfuric bacteria organic-biologically, the antibiotic metal and metallic salt powders were mixed to concrete, and a suppressing performance of the sulfate ion was assessed. For the sulfuric acid bacteria, a comparative evaluation of antimicrobial performance on neutralized concrete specimens were carried out, also by a rapid chloride penetration test, chloride penetration depths and diffusion coefficients were measured for antibiotic concrete in accordance with the amount of metal and metallic salt-based antibacterial agents. Eventually, by an observation of the biochemical state of the surface of concrete specimens exposed outdoors, the performance and applicability of antibiotic concrete were confirmed.

• Economic and Environmental Geology
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• v.36 no.3
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• pp.149-157
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• 2003

Deep sea core samples were taken in the southwestern part of the Ulleung Basin in order to characterize the properties of shallow gases in the sediment. Amount of shallow gases in the sediments were calculated by head space techniques, and chemical and isotopic compositions of hydrocarbon gases were analyzed. Geochemical analyses were carried out on the gas bearing sediments to find out relationship between natural gas contents and organic characteristics of the sediments. Seismic characteristics of shallow gases in the sediments were also examined in this study. The amount of the hydrocarbon gases in the sediments range from 0.01% to 11.25%. Calculation of volume of gas per volume of wet sediment varies from 0.1 to 82.0 ml HC/L wet sediment. Methane consists 98% of the total hydrocarbon gases except for two samples. Based on the methane content and isotopic composition$(\delta^{13}c)$: -94.31$\textperthousand$~-55.5$\textperthousand$), the hydrocarbon gases from the sediments are generated from bacterial activities of methanogenic microbes. Contents of hydrocarbon gases are variable from site to site. Volume of shallow gases in the sediments shows no apparent trends vs. either characteristics of organic matter or particle sizes of the sediments. Gas concentration is high in the area of seismic anomalies such as blanking zone or chimney structures in the section. Physicochemically the pore water and the formation water systems are saturated with gases in these areas. Concentration of hydrocarbon gases in the sediments in these area shows favorable condition for generation of gas hydrate, as far as the other conditions are satisfied.

• Economic and Environmental Geology
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• v.34 no.3
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• pp.301-306
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• 2001

Column tests were conducted to investigate the optimal condition of surfactant solution pH that can affect the removal efficiency in surfactant-assisted remediation. Toluene and 1,2,4-trichlorobenzene were chosen as the model hydrophobic substances. Two Iowa soils, Fruitfield sand and Webster clay loam, were leached with solutions of 4%(v/v) sodium diphenyl oxide disulfonate (DOSL, trade name Dowfax 8390), or 4%(v/v) trideceth-19-carboxylic acid (TDCA, trade name Sandopan JA36), or 4% (v/v) octylphenoxypoly ethoxyethanol (OPEE, trade name Triton X100). The test results revealed that a maximum removal of toluene and 1,2,4-trichlorobenzene was obtained at pH 10 of surfactant solution, and maximum recoveries of added toluene (94%) or 1 ,2,4- trichlorobenzene (97 %) were obtained for DOSL surfactant solution in Fruitfield sandy soil column. Increased removal efficiency by pH control of both toluene and 1,2,4trichlorobenzene was 16% and 20% for DOSL with Fruitfild sandy soil, respectively. In addition, the maximum recoveries of added toluene or I ,2,4-trichlorobenzene were 89% and 93% for DOSL surfactant solution in Webster clay loam soil column. The maximum increase of toluene and 1,2,4-trichlorobenzene removal was 26% and 19% for DOSL with Webster clay loam soil, respectively. These experimental results indicate that maintaining a high pH surfactant solution in surfactant-assisted remediation is desirable for efficient removal of NAPLs from contminated soils.