• Journal of Ginseng Research
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• v.45 no.2
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• pp.218-227
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• 2021

Background: Panax ginseng is one of the most important medicinal plants and is usually harvested after 5 to 6 years of cultivation in Korea. Heavy metal (HM) exposure is a type of abiotic stress that can induce oxidative stress and decrease the quality of the ginseng crop. Siderophore-producing rhizobacteria (SPR) may be capable of bioremediating HM contamination. Methods: Several isolates from ginseng rhizosphere were evaluated by in vitro screening of their plant growth-promoting traits and HM resistance. Subsequently, in planta (pot tests) and in vitro (medium tests) were designed to investigate the SPR ability to reduce oxidative stress and enhance HM resistance in P. ginseng inoculated with the SPR candidate. Results: In vitro tests revealed that the siderophore-producing Mesorhizobium panacihumi DCY119^T had higher HM resistance than the other tested isolates and was selected as the SPR candidate. In the planta experiments, 2-year-old ginseng seedlings exposed to 25 mL (500 mM) Fe solution had lower biomass and higher reactive oxygen species level than control seedlings. In contrast, seedlings treated with 10⁸ CFU/mL DCY119^T for 10 minutes had higher biomass and higher levels of antioxidant genes and nonenzymatic antioxidant chemicals than untreated seedlings. When Fe concentration in the medium was increased, DCY119^T can produce siderophores and scavenge reactive oxygen species to reduce Fe toxicity in addition to providing indole-3-acetic acid to promote seedling growth, thereby conferring inoculated ginseng with HM resistance. Conclusions: It was confirmed that SPR DCY119^T can potentially be used for bioremediation of HM contamination.

• Journal of Korean Society on Water Environment
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• v.36 no.6
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• pp.559-567
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• 2020

The abnomal responseses on growth and morphology of attached diatoms by various heavy metals were studied. Ulnaria ulna (Nitzsch) Compère was employed as experimental species and exposed to the five heavy metals such as Cu, Zn, Pb, Cd, and As with four concentrations (0, 0.01, 0.1, and 2 mg L-1), respectively. The samples of Ulnaria ulna were examined on the changes of cell growth and teratological forms on the 7th, 14th, 21th, and 28th day, respectively, after exposure to the heavy metals. The samples exposed to the highest concentration, 2.0 mg L-1, of all the heavy metals showed the most obvious decreases of growth. The samples exposed to Cd (μ=0.049day-1) and As (μ=0.048day-1) showed the highest decreasing rate of growth (p=0.021(Cd), p=0.002(As)) and the highest morphological changes of diatom valves were also samples exposed to Cd (10.41%) and As (10.13%) (p=0.009 (Cd), p=0.005(As)). In contrast, Pb induced the lowest decreasing rate (μ=0.090 day-1) and the least change in valve morphology (3.31%). The Cd and As showed relatively stronger effects on growth rates compared to Cu, Zn, and Pb. For the percentage of emergence of morphological species by the type, the highest percentage were observed in sampled exposed to type 1 (43.4%) and followed by type 2 (29.1%). The type 2 and 4 were most abundant in samples exposed to Zn and Pb while the type 3 was most abundant in Cd and As. The Cu induced only type 1, suggesting that the frequency of emergence of each type varied among hevay metals. This research suggests that the degrees of abnomal changes on growth rate and valve morphology of Ulnaria ulna can be used as a bioindicater species for heavy metal contamination in freshwater.

• The Korean Journal of Ecology
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• v.22 no.2
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• pp.95-100
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• 1999

The heavy metal concentrations in seawater and winkles (Littorina brevicula) collected from the Onsan bay area in southeast of Korea were analyzed. The heavy metal concentrations in the seawater obtained from the most polluted site showed approximately 189. 205. and 110 fold higher cadmium, copper. and zinc concentrations, respectively. than the uncontaminated control site. The contamination levels of these metals in winkles were 11.08 - 2.35, 334.5 - 212.5, and 426.0 - 499.2$\mu\textrm{g}$ per gram dry body weight. respectively. The concentrations of all three metals in both the seawater and winkles decreased gradually with increasing distance from Daejeong stream, suggesting the stream being the major source of heavy metal input into the bay. Among the four body parts of digestive gland and gonad. gill. kidney, and remaining tissue in contaminated winkles, kidney showed the highest accumulation level of cadmium: copper and zinc, however. were more or less distributed among the four body parts. Upon gel filtration chromatography of the cytosol from the kidney of cadmium induced winkles, one cadmium peak corresponded to the elution peak of horse kidney metallothionein.

• The Korean Journal of Ecology
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• v.27 no.4
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• pp.231-237
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• 2004

In this research we determined the levels of heavy metals in soil and metal-accumulating plants from a D military shooting site in the Kyungkido district of Korea. The data obtained may be useful in the development of methods for the efficient phytoremediation of contaminated soil. The total Cd, Cu, Pb, and Zn concentrations in the soil were found to be 1.67-5.04 mg/kg, 52.51-106.26 mg/kg, 37.24-90.32mg/kg, and 111.45-188.19mg/kg, respectively. These results show that the soil is contaminated with Cd and Cu, and this contamination is particularly severe in the case of Cd because of its high bioavailability (25-57% of the total metal in the soil is exchangeable). The high concentrations of heavy metals in the shoots of Persicaria thunbergii and Artemisia princeps var. orientalis indicate that these plants (all perennial herbs) accumulate heavy metal efficiently. Further, these plants were found to contain more Cd in its shoots (＞60% of the total metal found in the plant) than any other plant; these results indicate that these native species are particularly suited to use in Cd phytoextraction.

• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.12-17
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• 2013

Heavy metal contamination of soil and water from industrial sources remains a worldwide environmental concern. Concentrations of toxic metals were measured in soil from banks of the Han and Anyang rivers. Pre-monsoon samples contained the highest heavy metal concentrations (Cu > As > Pb > Cd > $Cr^{6+}$; up to 57.80, 38.23, 25.43, 2.21, 0.32 mg/kg, respectively), but concentrations decreased at all sites during the monsoon and post-monsoon seasons. Higher heavy metal concentrations in pre-monsoon samples may be attributed to dust pollution, especially from roads near the river. A gradual reduction in heavy metal concentrations during the rainy season may be due to washing out. The high concentration of metals could cause health problems, especially in residential areas.

• Journal of Sensor Science and Technology
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• v.28 no.6
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• pp.377-384
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• 2019

People currently spend more than 80% of their time indoors; therefore, the management of indoor air quality has become an important issue. The contamination of indoor air can cause sick house syndrome and various environmental diseases such as atopy and nephropathy. Formaldehyde gas, which is the main contaminant of indoor air, is lethal even with microscopic exposure; however, it is commonly used as an adhesive and waterproofing agent for indoor building materials. Therefore, there is a need for a gas sensor capable of detecting trace amounts of formaldehyde gas. In this review, we summarize recent studies on metal oxide-based semiconductor gas sensors for formaldehyde gas detection, methods to improve the gas-sensing properties of metal oxides of various dimensions, and the effects of catalysts for the detection of parts-per-billion level gases. Through this, we discuss the necessary characteristics of the metal oxidebased semiconductors for gas sensors for the development of next-generation sensors.

• Journal of Pharmacopuncture
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• v.10 no.1 s.22
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• pp.67-77
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• 2007

Objectives : Heavy metal contents in cultivated wild ginseng from Korea and China were evaluated for the safety purpose. Methods : Arsenic(As), cadmium(Cd), lead(Pb), mercury(Hg), copper(Cu), chromium(Cr), and selenium(Se) from the root, stem, and leaves of the Korean cultivated wild ginseng and the root of the Chinese cultivated wild ginseng were analyzed for the existence of heavy metal contents. Results : Most of heavy metals weren't detected in all the samples. Copper and lead were found in very minute volume and didn't reach the toxic concentration level of 10mg/kg. Samples used in the test were grown in non-contaminated areas, free from heavy metal contamination. Conclusions : Based on above results, cultivated wild ginseng from Korea and China are relatively safe from the heavy metal exposure. But for more rigorous quality control, an epidemiological survey using the samples from more diverse areas should be conducted.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.26-29
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• 2004

High density plasma fluorinated silicate glass (HDP FSG) is used as a gap fill film for metal-to-metal space because of many advantages. However, FSG films can cause critical problems such as bonding issue of top metal at package, metal contamination, metal peel-off, and so on. It is known that these problems are caused by fluorine penetration out of FSG film. To prevent it, FSG capping layers such like SRO (Silicon Rich Oxide) are needed. In this study, their characteristics and a capability to block fluorine penetration for various FSG capping layers are investigated. Normal stress and High stress due to denser film. While heat treatment to PETEOS caused lower blocking against fluorine penetration, it had insignificant effect on SiN. Compared with other layers, SRO using ARC chamber and SiN were shown a better performance to block fluorine penetration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.300-303
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• 2004

To fill the gap of films for metal-to-metal space High density plasma fluorinated silicate glass (HDP FSG) is used due to various advantages. However, FSG films can have critical drawbacks such as bonding issue of top metal at package, metal contamination, metal peel-off, and so on. These problems are generally caused by fluorine penetration out of FSG film. Hence, FSG capping layers such like SRO(Silicon Rich Oxide) are required to prevent flourine penetration. In this study, their characteristics and a capability to block fluorine penetration for various FSG capping layers are investigated through FTIR analysis. FTIR graphs of both SRO using ARC chamber and SiN show that clear Si-H bonds at $2175{\sim}2300cm^{-1}$. Thus, Si-H bond at $2175{\sim}2300cm^{-1}$ of FSG capping layers lays a key role to block fluorine penetration as well as dangling bond.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.190-198
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• 2008

There is an increasing concern over heavy metal contamination of paddy soils and the subsequent translocation of heavy metals to rice. Objective is to monitor the status and long-term trend of heavy metal contamination in paddy soils, periodically. In 2007 survey, the average concentrations of As(arsenic), Cd(cadmium), Cu(copper), Ni(nickel), Pb(lead), and Zn(zinc) in 2,010 paddy soils nationwide were 0.87, 0.08, 3.33, 1.19, 4.95 and $4.67mg\;kg^{-1}$, respectively. Few sites, which were contaminated by As in 2003 and 2007 survey and by Ni in 1999 and 2007 survey, were over the threshold level for soil contamination designated by the Soil Environmental Conservation Act in Korea. Long-term change was shown that As, Ni, and Zn were gradually increased whereas Cd and Cu were decreased. In the distribution of extractable heavy metal contents, the modes of each heavy metal content were similar with the average contents of each heavy metals. Mean value of heavy metals except copper in paddy soils was higher than median value. It means that the downward distribution of heavy metal content in paddy rice was shown against normal distribution.