• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.373-378
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• 2019

In the marine area, the salt concentration in the soil increases, and the inland heavy metal pollution increases the damage of plants. In the inland industrial development area, researches on the genetic resources of plants together with the heavy metal accumulation of Co, Ni, Zn, and so on are required. Both of these problems have caused scientists to work hard to find plants that are likely to cause stress in plant roots. In this study, seeds of Arabis stelleri var. japonica collected near the shore were used for germination. The growth and development and tolerance of both Arabis and Arabidopsis seeds were investigated under laboratory culture conditions. As a result, Arabis showed resistance about 3 times in 250 mM nickle and cobalt, and more than 4 times in 1 mM zinc when compared to Arabidopsis. The tolerance of Arabis to Na salts increased by 20% or more at 50 mM concentration and Arabis was resistant to heavy metals and salt concentration. The accumulation of Na ions in the body was measured as a preparation for studying the intracellular mechanism. As a result, it showed a further decrease in resistance to ground water roots. It is considered that the activity of the exporting gene is important rather than the mechanism of accumulation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.330-333
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• 2003

Recently electrokinetic process is known to be a promising remediation technology for the contaminated soils with heavy metals, radionuclides, organic matters, and so on. The contaminants in electrokinetic technology are removed mainly by three mechanisms; electroosmosis, electromigration, and electrophoresis. When direct current is introduced between two electrodes planted in soil, a large amount of hydrogen ions is formed and moves from anode to cathode with the other cations contained in electrolyte. The water flow caused by tile movement of cations is called as electroosmosis. Especially for non-ionic pollutants, the electroosmotic flow(EOF) is the most important removal mechanism among them and transports contaminants from anode to cathode along the water flow. In this study, characteristics of electroosmotic flow was investigated according to the resistance state of soil. The decrease, maintenance, and increase of soil resistance could be obtained by controlling ions in soil. When the resistance of soil was decreasing or maintained, the EOF is proportional to electric current and voltage, respectively and when the resistance was increasing, the EOF is proportional to only electric current not voltage.

• Journal of the Korean institute of surface engineering
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• v.53 no.5
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• pp.249-256
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• 2020

As the size of manufacturing equipment for LCD and OLED displays increases, replacement of existing heavy stainless steel components with light metals, such as aluminum alloys, is being more important in semiconducting and display manufacturing industries. To use aluminum alloys for components in semiconducting and display industries, it is important to develop a new anodization method for improved performance of anodic oxide films than conventional anodization method based on sulfuric acid. In this work, optimum applied current density and the best sealing methods for anodic oxide films in 3% oxalic acid were explored. Experimental results showed 2.5 A/dm2 is the best applied current density for improved hardness and dielectric breakdown voltage. Sealing of the anodic oxide films further improved their hardness, dielectric breakdown voltage and resistance to HCl, by which application of anodic oxide films become applicable for components in semiconducting and display industries.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1119-1129
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• 2023

Seeds are colonized by diverse microorganisms that can improve the growth and stress resistance of host plants. Although understanding the mechanisms of plant endophyte-host plant interactions is increasing, much of this knowledge does not come from seed endophytes, particularly under environmental stress that the plant host grows to face, including biotic (e.g., pathogens, herbivores and insects) and abiotic factors (e.g., drought, heavy metals and salt). In this article, we first provided a framework for the assembly and function of seed endophytes and discussed the sources and assembly process of seed endophytes. Following that, we reviewed the impact of environmental factors on the assembly of seed endophytes. Lastly, we explored recent advances in the growth promotion and stress resistance enhancement of plants, functioning by seed endophytes under various biotic and abiotic stressors.

• Journal of Life Science
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• v.15 no.4 s.71
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• pp.566-571
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• 2005

A natural habitat bacterium, Enterobacter cloaceae K41 was isolated from fresh water plant root and identified. This strain was used to investigate heavy metal resistance. The optimal growth conditions of the bacterium were LB medium containing$1\%$ yeast extract, $1\%$ lactose, $1\%$ NaCl, pH 7.0, at $37^{\circ}C$, and for 24 hours on a shaker. The minimal inhibitory concentration (MIC) of heavy metals against E. cloaceae KCTC2519 and E. cloaceae K41 was compared. The MIC of E. cloaceae K41 was 150 ppm in Cu, 50 ppm in Cd whereas that of the standard strain was 50 ppm in Cu but no growth was observed either Cd or two mixed heavy metal solution. The presence of plasmid was cleared from the isolated strain whereas no possession from the standard strain. The plasmid from E. cloaceae K41 was transformed into E. coli $DH5{\alpha}$. The MIC of transformed strain increased resistance 7 times in Cu and 6 times in Cd by insertion of this plasmid. The metal adsorption of the transformant was increased 1.3 times in Cu and 1.5 times in Cd indicating the plasmid was responsible for heavy metal resistance.

• Journal of the Korean Wood Science and Technology
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• v.25 no.4
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• pp.92-98
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• 1997

To make good use of chitosan forming complex with heavy metals in wood preservative treatment, woods impregnated with chitosan and copper sulfate were prepared. Amounts of leached copper, decay resistance, anti-mold efficacy, iron corrosion rates, moisture regain rates and degradation pattern in chitosan pre-treated and untreated wood were compared. After leaching test, amounts of leached copper from chitosan pre-treated wood had a much smaller than chitosan untreated wood, and good decay resistance was retained even after leaching test. From these results, it was proved that chitosan-copper complex formed in wood played and important role for decay durability. In chitosan pre-treated wood, damage values by test molds became remarkably smaller, but the growth of test molds was not perfectly inhibited. Distinct differences in iron corrosion rates between chitosan pre-treated and untreated woods was not recognized but chitosan pre-treated wood showed the lower moisture regain rates than chitosan untreated wood because of water insoluble chitosan membrane formed in wood. After leaching test, the tracheid walls in the wood treated with 2.0% copper sulfate only were eroded by the fungal attacks, but those in the wood pre-treated with chitosan remained almost intact.

• Korean Journal of Metals and Materials
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• v.49 no.11
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• pp.905-909
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• 2011

The formation of front metal contact silicon solar cells is required for low cost, low contact resistance to silicon surfaces. One of the available front metal contacts is Ni/Cu plating, which can be mass produced via asimple and inexpensive process. A selective emitter, meanwhile, involves two different doping levels, with higher doping (${\leq}30{\Omega}/sq$) underneath the grid to achieve good ohmic contact and low doping between the grid in order to minimize the heavy doping effect in the emitter. This study describes the formation of a selective emitter and a nickel silicide seed layer for the front metallization of silicon cells. The contacts were thickened by a plated Ni/Cu two-step metallization process on front contacts. The experimental results showed that the Ni layer via SEM (Scanning Electron Microscopy) and EDX (Energy dispersive X-ray spectroscopy) analyses. Finally, a plated Ni/Cu contact solar cell displayed efficiency of 18.10% on a $2{\times}2cm^2$, Cz wafer.

• The Korean Journal of Ecology
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• v.11 no.1
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• pp.29-36
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• 1988

This present study has been carried out to examine the correlation between the distribution of the coliform bacterial plasmids and the viability test against heavy metals in the upper stream of Han river(Gapyung; clean water) and the its basin (Anyang Cheon; polluted water). And the distribution of plasmids were examined to be used as trophic indicator for analysis between the clean and polluted waters. 1. A total of 110 isolates were analyzed for the presence of plasmids by means of the boiling method and agarose gel techniques. Plasmids were significantly more frequent in the strains which had been isolated from the clean water (14.3%). Also, there were much higher multiplicity of plasmids at the polluted water(41.0%), compared with the clean water (33.0%). By the comparision between molecular weight of bacterial plasmids in the clean water and those of polluted water, there were no significant differences of the clean water from the polluted water, to such extent as 30.0%, 28.6%, respectively, in frequency for occurrence of high molecular weight plasmids iver 35.8% Mdal. 2. Each isolate was carried out the resistance test for mercury(10-5M), nickel(10-3M) and arsenic (0.1%). At the polluted site, the survival ability of the plasmid-carrying straings(Hg, 31.0%l Ni, 5.7%; As, 65.7%) was higher than that of the non plasmid-carrying strains(Hg, 12.1%; Ni, 3.0%; As, 54.6%). This trend was more remarkable in the clean site (plasmid-carrying strains: 16.7%,-,-). As a result it is suggested that plasmids could be used as an indicator of a certain types of water pollution. In addition, heavy metals might have inflyenced, some extent, to the distribution of plasmids in the environment which has been surveyed in the present study.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.1
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• pp.53-62
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• 1990

High speed and heavy cutting performed for improving the surface quality and productivity, are often prevented due to chatter phenomena. Chatter is a violent relative vibration between workpiece and tool in machining of metals, and is an important limiting factor of production rate and surface quality, and reduces the tool life and the dynamic performance of machine tool itself. In this study, in order to suppress the chatter, a modified tool-post combined with the spring and damper was designed and used in the actual cutting test. The results of this study are summerized as follows; The spring and damper adopted in the modified tool-post have the suppressing effects of chatter, and there exists an optimum combination between spring constant and damping ratio.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.593-601
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• 2012

Heavy metals and metalloids removal can be considered as one of the most important world challenges because of their toxicity and direct impact on human health. Many processes have been introduced but biological processes of remediation seem to offer the most suitable solution in terms of efficiency and low cost. Actinobacteria constitute one of the major microbial populations in soil, and this can be attributed to their adaptive morphological structure as well as their exceptional metabolic power. Among microbes, actinobacteria are morphologic intermediate between fungi and bacteria. Studies on microbial diversities in metal contaminated lands have shown that actinobacteria may constitute a dominantly active microbiota in addition to ${\alpha}$ Proteobacteria. Furthermore, isolation studies have shown metal removal mechanisms which are reminiscent of notable multiresistant strains, such as Cupriavidus metallidurans. Apart from members of genus Streptomyces, which produce more than 90% of commercialized antibiotics, and the nitrogen fixing Frankia, little attention has been given to other members of this phylum. This is because of difficult culture condition requirements and maintenance. In this review, we focused on specific isolation of actinobacteria and their potential applications in metal bioremediation and plant growth promotion.