• Journal of Wetlands Research
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• v.24 no.3
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• pp.204-212
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• 2022

The LID technique began to be applied in Korea after 2009, and LID facilities are installed and operated for rainwater management in business districts such as the Ministry of Environment, the Ministry of Land, Infrastructure and Transport, and LH Corporation, public institutions, commercial land, housing, parks, and schools. However, looking at domestic cases, the application cases and operation periods are insufficient compared to those outside the country, so appropriate design standards and measures for operation and maintenance are insufficient. In particular, LID facilities constructed using LID techniques need to maintain the environment inside LID facilities because hydrological and environmental effects are expressed by material circulation and energy flow. The LID facility is designed with the treatment capacity planned for the water circulation target, and the proper maintenance, vegetation, and soil conditions are periodically identified, and the efficiency is maintained as much as possible. In other words, the soil created in LID is a very important design element because LID facilities are expected to have effects such as water pollution reduction, flood reduction, water resource acquisition, and temperature reduction while increasing water storage and penetration capacity through water circulation construction. In order to maintain and manage the functions of LID facilities accurately, the current state of the facilities and the cycle of replacement and maintenance should be accurately known through various quantitative data such as soil contamination, snow removal effects, and vegetation criteria. This study was conducted to investigate the current status of LID facilities installed in Korea from 2009 to 2020, and analyze soil changes through the continuity and current status of LID facilities applied over the past 10 years after collecting soil samples from the soil layer. Through analysis of Saturn, organic matter, hardness, water contents, pH, electrical conductivity, and salt, some vegetation-type LID facilities more than 5 to 7 years after construction showed results corresponding to the lower grade of landscape design. Facilities below the lower level can be recognized as a point of time when maintenance is necessary in a state that may cause problems in soil permeability and vegetation growth. Accordingly, it was found that LID facilities should be managed through soil replacement and replacement.

• The Journal of Engineering Geology
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• v.33 no.1
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• pp.85-103
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• 2023

The in-situ remediation of a solidified stratum containing a large amount of fine-texture material like clay or organic matter in contaminated soil faces limitations such as increased remediation cost resulting from decreased purification efficiency. Even if the soil conditions are good, remediation generally requires a long time to complete because of non-uniform soil properties and low permeability. This study assessed the remediation effect and evaluated the field applicability of a methodology that combines pneumatic fracturing, vacuum extraction, and plasma blasting (the PPV method) to improve the limitations facing existing underground remediation methods. For comparison, underground remediation was performed over 80 days using the experimental PPV method and chemical oxidation (the control method). The control group showed no decrease in the degree of contamination due to the poor delivery of the soil remediation agent, whereas the PPV method clearly reduced the degree of contamination during the remediation period. Remediation effect, as assessed by the reduction of the highest TPH (Total Petroleum Hydrocarbons) concentration by distance from the injection well, was uncleared in the control group, whereas the PPV method showed a remediation effect of 62.6% within a 1 m radius of the injection well radius, 90.1% within 1.1~2.0 m, and 92.1% within 2.1~3.0 m. When evaluating the remediation efficiency by considering the average rate of TPH concentration reduction by distance from the injection well, the control group was not clear; in contrast, the PPV method showed 53.6% remediation effect within 1 m of the injection well, 82.4% within 1.1~2.0 m, and 68.7% within 2.1~3.0 m. Both ways of considering purification efficiency (based on changes in TPH maximum and average contamination concentration) found the PPV method to increase the remediation effect by 149.0~184.8% compared with the control group; its average increase in remediation effect was ~167%. The time taken to reduce contamination by 80% of the initial concentration was evaluated by deriving a correlation equation through analysis of the TPH concentration: the PPV method could reduce the purification time by 184.4% compared with chemical oxidation. However, the present evaluation of a single site cannot be equally applied to all strata, so additional research is necessary to explore more clearly the proposed method's effect.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.421-433
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• 2023

The final disposal of spent nuclear fuel(SNF) from nuclear power plants takes place in a deep geological repository. The metal canister encasing the SNF is made of cast iron and copper, and is engineered to effectively isolate radioactive isotopes for a long period of time. The SNF is further shielded by a multi-barrier disposal system comprising both engineering and natural barriers. The deep disposal environment gradually changes to an anaerobic reducing environment. In this environment, sulfide is one of the most probable substances to induce corrosion of copper canister. Stress-corrosion cracking(SCC) triggered by sulfide can carry substantial implications for the integrity of the copper canister, potentially posing a significant threat to the long-term safety of the deep disposal repository. Sulfate can exist in various forms within the deep disposal environment or be introduced from the geosphere. Sulfate has the potential to be transformed into sulfide by sulfate-reducing bacteria(SRB), and this converted sulfide can contribute to the corrosion of the copper canister. Bentonite, which is considered as a potential material for buffering and backfilling, contains oxidized sulfate minerals such as gypsum(CaSO4). If there is sufficient space for microorganisms to thrive in the deep disposal environment and if electron donors such as organic carbon are adequately supplied, sulfate can be converted to sulfide through microbial activity. However, the majority of the sulfides generated in the deep disposal system or introduced from the geosphere will be intercepted by the buffer, with only a small amount reaching the metal canister. Pyrite, one of the potential sulfide minerals present in the deep disposal environment, can generate sulfates during the dissolution process, thereby contributing to the corrosion of the copper canister. However, the quantity of oxidation byproducts from pyrite is anticipated to be minimal due to its extremely low solubility. Moreover, the migration of these oxidized byproducts to the metal canister will be restricted by the low hydraulic conductivity of saturated bentonite. We have comprehensively analyzed and summarized key research cases related to the presence of sulfates, reduction processes, and the formation and behavior characteristics of sulfides and pyrite in the deep disposal environment. Our objective was to gain an understanding of the impact of sulfates and sulfides on the long-term safety of high-level radioactive waste disposal repository.

• Conservation Science in Museum
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• v.29
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• pp.133-152
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• 2023

This study references preceding studies to examine the history of paint application techniques using various paints in the past, with the aim to contribute to the long-term preservation of large military cultural heritage assets situated outdoors. To this end, the study compared the findings of preceding research with the findings of an analysis conducted on a H-13 helicopter housed at the War Memorial of Korea. Upon collecting and analyzing samples from three grounded WWII aircraft from above-ground by preceding studies, it was confirmed from each sample that the various chemical properties of chrome ensured the effectiveness of the protective coating. The compound was first tested as a corrosion-inhibiting pigment in the early 1940s and proved its excellent moisture-resistant properties over the course of 80 years, despite the deterioration of the paint layer and long-term exposure to the natural environment. For this reason, it has been widely used as a corrosion inhibitor for aluminum alloys in the aviation industry. In other word, the most widely-used material for preventing corrosion was an organic primer containing chromate. In this study, based on the paint analysis of a H-13 helicopter operated in the Korean War, it was shown that the second layer, consisting of the primer, contains chromium oxide (Cr₂O₃). In addition, it was estimated that red lead tetraoxide (Pb₃O₄) was used for the vehicle. Analysis results and data from previous studies can help to confirm the continued effectiveness of corrosion prevention function provided by chromate. Meanwhile, the result of infrared spectroscopy analysis confirmed the use of alkyd resin. In the future, comparisons with a more diverse range of artifacts will allow the identification of changes in the manufacturing technology of paints used to protect alloys from corrosion.

• Korean Journal of Heritage: History & Science
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• v.55 no.4
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• pp.24-36
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• 2022

The Bonghwang-dong ruins in Gimhae, the central area of Geumgwan Gaya, is presumed to be the site of the royal palace, and excavations have been in progress at the Gaya National Cultural Heritage Research Institute. According to a research conducted by lowering the level to the base layer on the north side of the site, mostly shell layers composed of oysters were confirmed, and soil composed of different material was alternately filled in to form a site construction. In other words, it can be seen that there was work at the site of the Bonghwang-dong ruins that required large-scale labor, such as building ramparts and embankments. There is stratigraphic confusion such as showing different age values in the same shell layer through a chronological analysis of organic matter and charcoal in the sedimentary layer, and deriving a result value in the upper layer ahead of the lower layer. In addition, open-sea diatoms are observed not only in the sedimentary layers, but also the pits. Therefore, it is judged that the soil constituting the ruins was brought from the outside. The Bonghwang-dong ruins are located inside the commonly called Bonghwang earthen ramparts, where many excavation organizations conducted research within the estimated range of the earthen fortifications. As a result, it was found that it was similar to the sedimentary layers of the ruins of the Three Kingdoms Period, which were investigated along with the ruins of Bonghwang-dong. Through this, the surrounding ruins, including those of Bonghwang-dong, were located close to paleo-Gimhae Bay, so it is believed that the soil brought from the surroundings was used to reinforce the ground. As a result of the excavation research on the Bonghwang-dong ruins conducted so far, it was found by sedimentary layer analysis and soil experiments that the ruins were created on stable land. Relics excavated in the sediments of the ruins and carbon dating data show that Bonghwang-dong carried out large-scale civil construction work in the 4th century to build the site, which clearly shows the status of Geumgwan Gaya.

• Journal of Food Hygiene and Safety
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• v.38 no.6
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• pp.517-527
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• 2023

This study aimed to examine the possibility of upcycling extracts of Angelica keiskei and Oenanthe javanica juice by-products through comparing enzyme extraction (EE) and complex extraction (CE) methods to increase the extraction yield and flavor of materials. A higher extraction yield was obtained for free amino acid content with EE and CE for A. keiskei and O. javanica juice by-products, respectively, and a higher extraction efficiency was achieved with juice by-products than with extracts prepared from raw materials before juice production. The content of major amino acids varied depending on the extraction method used. When used according to the characteristics of the extract, their use as a functional material was confirmed along with improvement in the flavor of the food. Consistently high extraction yields for organic acid and sugar levels were obtained with CE in A. keiskei and O. javanica juice by-products. The DPPH radical scavenging ability and TPC were consistently high with CE in A. keiskei and O. javanica juice by-products; the increase in extracted content was likely because of the reaction between the ethanol used for CE and the phenolic compounds. However, because the antioxidant capacity of the juice by-product extracts was somewhat lower than that of the extracts from raw materials before juice production, the amount used should be reviewed. The TFC was found to be higher in extracts obtained with EE than with CE for A. keiskei juice by-products; however, no significant difference was observed between EE and CE in the O. javanica juice by-products. Through this study, the taste compounds and antioxidant properties of extracts obtained from juice by-products produced after the production of A. keiskei and O. javanica green juice were analyzed, and the availability of high value-added materials was confirmed. Based on these research results, expanding specific R&D for practical use should be explored.

• Korean Journal of Soil Science and Fertilizer
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• v.7 no.2
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• pp.71-97
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• 1974

Many studies on the changes of the materials in the water-logged paddy soil have been reported, but there will be several problems to apply them on the field soil. The main differences between the method of soil packed in beaker or column tube to that of natural field furrow slice are with or without of the rice root and the effect of water percolation. On the other hand, the mechanism of the water percolation on the changes of material in the natural field furrow slice are gradually understood. The purpose of this experiment is to know the effect of the rice cultivation on the chemical and physical changes of material in the water-logged paddy soil. Obtained results are as follows. 1. The physical and chemical changes on the water-logged paddy soil in the non-planted control-plot were nearly the same as the beaker or column tube experiment, while in the planted plot, slightly altered patterns were observed. 2. The relation between the number of tillers and total cation, $Ca^{{+}{+}}$, $Mg^{{+}{+}}$, Fe and Mn in the leachate showed very high significance. T hisresult showed that the leaching of those cation was promoted by growing of the rice r- of the rice root. 3. On the other hand, the concentration of the potassium, silica and phosphorus in leachates was gradually decreased and that of $NH_4$-N could not detect after the stage of active tillering. These facts revealed that such components were absorbed by rice plant. 4. The highly significant correlation between the number of tillers and the concentration of the total cation, $Ca^{{+}{+}}$, $Mg^{{+}{+}}$, $Fe^{{+}{+}}$, Fe and Mn in the percolated water was observed except that of $Mg^{{+}{+}}$. It was also showed that the rice root promoted the leaching of those cation. 5. The very high significance in the correlation between $HCO_3{^-}$ and the number of tillers indicated that the higher activity of the rice root was, the more $HCO_3{^-}$ concentration in the leachate was increased. 6. The relationship between the $HCO_3{^-}$ and the total cation, $Ca^{{+}{+}}$, $Mg^{{+}{+}}$, $Fe^{{+}{+}}$, Fe and Mn was appeared very highly significant. $HCO_3{^-}$, the metabolite of the rice root, promoted the leaching of $Ca^{{+}{+}}$, $Mg^{{+}{+}}$, $Fe^{{+}{+}}$ and Mn. This fact might be a result that these cations were leached as the form of bicarbonate. 7. The iron in the leachate was the form of $Fe^{{+}{+}}$ and the correlation between $Fe^{{+}{+}}$ and $HCO_3{^-}$ was very highly significant. This result indicated that it seemed to be ferrous bicarbonate when it is leached out. 8. In the rhizosphere, ferrous iron was decreased gradually and the concentration of glucose was as high as 2 to 3 times in comparison with the other parts of the soil. These facts were the same as the previous reports in which rhizosphere was oxidized by the oxigen excreted from the root, and was enriched by the organic matter which was also excreted from the root and accumulated residues of the root. 9. ${\beta}$-Glucosidase and phosphatase activity in the rhizosphere was higher than that of the other parts of the soil. This facts might be attributed to the vigorous activity of microorganism in the rhizosphere where glucose concentration was high. 10. The pH in the leachate of the planted plot was lower than that of control, and the Eh on the planted soil was elevated in the last stage.

• Applied Biological Chemistry
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• v.15 no.3
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• pp.213-219
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• 1972

In order to utilize sweet potatoes for the material of Takju, brewing experiments with raw sweet potatoes, sweet potato chips powder and its koji were conducted; and various tests were carried out on effect of the treatments of acid, alkali, polyphenol oxidase inhibitor, oxidizing and reducing agents upon the prevention against coloring of sweet potato chips by steaming, and on peeling effect of sweet potatoes by the alkali and heat treatments. The results obtained were as follows. 1) In the case of brewing with raw sweet potatose, each plot showed low acid and ethanol content, and its finished Takju had an undersirable color and odor. The plots which were mashed after peeling showed higher ethanol contents than the plots mashed without peeling. 2) In the case of brewing with sweet potato chips powder, each plot contained considerably more amount of ethanol than the plots brewed with raw sweet potatoes, white it contained less amount of acid. The ethanol contents of the plots using wheat bran koji were $10.5{\sim}11.4$ per cent 4 days after mashing, and were higher than those of the plots using malts powder. Their finished Takju was inferior in quality because of the lack of acid and being darkened gradually in process of time. 3) The kojies which were made of sweet potato chips powder with Neurospora sitophila or Aspergillus oryzae had good appearance, but the Takju mashes brewed with these contained remarkably less amount of ethanol. 4) Effect of the treatments of acid, alkali, polyphenol oxidase inhibitor and organic solvents such as ether and ethanol upon the prevention against coloring of sweet potato chips was not recognized. Alum and burnt alum were effective a little on the decolorization, and among the oxidizing and reducing agents tested, potassium permanganate was most effective. 5) Darkening of sweet potato chips powder in course of heating after mixing with water was not affected by pectin and amino acids, but by tannin. 6) Sweet potatoes were not peeled easily by friction after soaking in the boiling solution of 3 per cent alkali for 6 minutes and peeled in boiling water for 12 minutes. From the viewpoint of the results above mentioned, it seems to be necessary to study further on the isolation of microorganisms which are able to decompose the coloring substances and yeasts which are adequate for the fermentation of sweet potatoes in order to utilize sweet potatoes for Takju brewing, because brewing with raw sweet potatoes, sweet potato chips powder and its koji was unsuccessful, and effect of the various treatments on the decolorization of sweet potatoes was not recognized.

• Applied Biological Chemistry
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• v.13 no.2
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• pp.153-170
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• 1970

1. Isolation and identification of amylase-producing bacteria. The powerful strain A-12 and S-8 were respectively isolated from air and soil after screening a large number of amylase-producing bacteria. Their bacterial characteristics have been investigated and it has been found that all characteristics of strain A-12 and S-8 are similar to Bac. subtilis of Bergey's manual except for the acid formation from a few carbohydrates and the citrate utilization, i.e., the strain A-12 shows negative in the citrate utilization, and the acid formation from arabinose and xylose, S-8 shows negative in the acid formation from xylose. 2. Amylase production by Liquid cultures with solid materials. Several conditions for amylase production by strain A-12 in stationary cultures have been studied. The results obtained are as follows. (1) The optimum conditions are:temperature $35^{\circ}C$, initial pH 6.5 to 7.0 and incubation time 3 to 4 days. (2) The amylase production is not affected by the preservation period of the stock cultures. (3) Among the various solid material, the defatted soy bean is found to be the best for t1e amylase production. However, the alkali treatment of the defatted soy bean gives no effect contrary to the cage of defatted rape seed. The addition of soluble starch to the alkali extract of defatted soy bean shows the increased amylase production. (4) Up to 1% addition of ethanol to carbon dificient media gives the improved amylase production, whereas the above effect is not found in the case of carbon rich media. (5) The amylase production can be increased 2.5 times when 10% of defatted soy bean is admixed to cheaply available wheat bran. (6) The excellent effect is found for amylase production when 20% of wheat bran is admixed to defatted dry milk which is a poor medium. The activity is found to be $D^{40^{\circ}}_{30'}$ 7,000(L.S.V. 1,800) in 10% medium. (7) No significant effect is observed due to the addition of various inorganic salts. 3. Amylase production by solid cultures. Several conditions for amylase production by strain A-12 in wheat bran cultures have been studied and the results obtained are as follows. (1) The optimum conditions: are temperature $33^{\circ}C$, incubation lime 2 days, water content added 150 to 175% and the thickness of the medium 1.5cm, The activity is found to be $D^{40^{\circ}}_{30'}$ 36,000(L.S.V. 15,000) (2) No significant effect is found in the case of the additions of various organic and inorganic substances.

• Food Science and Preservation
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• v.22 no.3
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• pp.353-360
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• 2015

Yakju, a Korean traditional alcoholic beverage, is made from rice and Nuruk. In this study, the fermentation characteristics of Yakju was investigated using rice and rice starch. Ingredients was classified into raw material (rice, rice starch) and starter (enzyme supplements, modified Nuruk, traditional Nuruk, and yellow rice koji) for fermentation. The crude protein content of rice, rice starch, and starter were determined as follows (%): rice 6.69, rice starch 0.44, enzyme supplements 7.84, modified Nuruk 15.29, traditional Nuruk 14.28, and yellow rice koji 7.28. The alcohol content of rice with traditional Nuruk ($20.13{\pm}0.12%$) was higher than other Yakju. The concentration of organic acids of rice starch-based Yakju (389.83~538.34 mg%) was higher than that of rice Yakju (259.27~357.70 mg%). The concentration of nitrogen compound of rice Yakju (498.38~5976.93 ppm) was higher than that of rice starch-based Yakju (600.43~4463.79 ppm). In line with these findings, further studies will be necessary for the quality analysis of the rice, rice starch and fermented starter (enzyme supplements, modified Nuruk, traditional Nuruk and yellow rice koji).