• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.333-334
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• 2001

미량금속은 구리 (Cu), 아연 (Zn), 철 (Fe), 망간 (Mn) 등 정상적인 생화학적 반응과정에 필수적인 것과 카드뮴 (Cd), 수은 (Hg), 크롬(Cr), 납(Pb) 등 어떤 확실한 생화학적 기능을 가지지 않는 종류로 나누어지는데, 특히 후자의 경우는 수서환경에서 중요한 오염원으로 작용하고 있다 (Viarengo, 1985). 수은은 우리 생활과 매우 밀접하여 건전지, 온도계, 압력계, 의약품 등의 재료로 사용상 주의가 필요한 중금속이다. 수은은 알킬 형태로 체내에 축적되며, 아주 강한 독성을 나타낸다. (중략)

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.1
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• pp.11-18
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• 2004

The eruption of permanent teeth represents the movement in the alveolar bone before appearance in oral cavity, to the occlusal plane after appearance in oral cavity, and additive movement after reaching th the occlusal plane. Tooth eruption is mostly controlled by genetic signals. The eruption stage is divided to preeruptive alveolar stage, alveolar bone stage, mucosal stage according to the process of growth and development. If the disturbance is occured in any stage of eruption, tooth does not erupt. The cause of eruption disturbance are ectopic position of the tooth germ, obstruction of the eruption path and defects in the follicle or PDL. In the treatment of eruption disturbance, surgical procedures are commonly used. There are three kind of surgical procedure ; surgical exposure, surgical repositioning, surgical exposure and traction Surgical exposure is basic procedure. This involves removal of mucosa, bone, lesion that are surrounding the teeth, dental sac when necessary to maintain a patent channel between the crown and the normal eruptive path into the oral cavity. To ensure this patency, many techniques including cementation of a celluloid crown, packing with gutta-percha or zinc oxide-eugenol, or a surgical pack, are used. When surgical exposure is conducted, operators should not expose any part of cervical root cement and not injure periodontium or root of adjunct tooth. After surgical exposure, tooth should be surrounded by keratinized gingiva. There is direct relationship between the extent of development of pathophysiologic aberrations and the intensity of the manipulative injury inflicted on the tooth by surgical treatment, so operator should consider this thing. In these cases, surgical exposure is conducted on Maxillary 1st milars that have a eruption disturbance and improve the eruption disturbance effectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.681-686
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• 2017

Degradation is commonly observed in field-aged PV modules due to corrosion of the photovoltaic ribbon. The reduced performance is caused by a loss of fill factor due to the high series resistance in the PV ribbon. This study aimed to mitigate the degradation by corrosion using five sacrificial anodes - Al, Zn and their alloys - to identify the most effective material to mitigate the corrosion of the PV ribbon. The corrosion behavior of the five sacrificial anode materials were examined by open circuit potential measurements, potentiodynamic polarization tests, and galvanic current density and potential measurements using a zero resistance ammeter. Immersion tests for 120 hours were also conducted using materials and damp heat test tests were performed for 1500 hours using 4 cell mini modules. The Al-3Mg and Al-3Zn-1Mg sacrificial anodes had a low corrosion rate and reduced drop in power, making then suitable for long-term use.

• Journal of Korean Society of Steel Construction
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• v.28 no.2
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• pp.97-108
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• 2016

Thermally sprayed metals or organic coatings is often used in corrosion protection of steel structures. Duplex coating systems of thermally sprayed metal in combination with organic coating are selected as a new generic type of coatings on steel structures under the highly corrosive environments. In this study, three types of corrosion tests were carried out on four types of thermal sprayed specimens with sealing: zinc, zinc-15%aluminum alloy, aluminum and aluminum-5%magnesium alloy, four types of duplex coated specimens; thermally sprayed metals in combination with paint of acrylic urethane, and painted specimens. NORSOK M-501, Wet/dry cyclic seawater tests and outdoor exposure tests of nine types of specimens were conducted. From the corrosion test results, weathering performance of them were presented.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.12
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• pp.828-834
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• 2012

The ecotoxicity detection device for preliminary test (Test jig) was manufactured to develop the biological early warning system using Vibrio fischeri. In this study, the ecotoxicity detection charateristics of the Test jig was investigated for 6 heavy metals (Cr, Zn, Pb, Cd, Cu and Hg). It was observed that relative luminescence unit (RLU) of Vibrio fischeri constantly decreased by the concentrations of the tested heavy metals. In contrast with other heavy metals, RLUs of Pb and Hg constantly decreased even at low concentrations. RLU of Hg drastically decreased when its concentration increased from 0.13 mg/L to 0.25 mg/L. $EC_{50}$ values of Cr, Zn, Pb and Cd gradually decreased with exposure time, whereas there was no significant change in $EC_{50}$ values of Cu and Hg with time. On the other hand, $EC_{50}$ values between the Test jig and Reference device were compared to evaluate the ecotoxicity detection performance of the Test jig. No big difference was found in $EC_{50}$ vlaues between the two devices, indicating that the Test jig could be applied as the ecotoxicity detection device for heavy metals.

• Korean Journal of Environmental Biology
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• v.30 no.2
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• pp.128-135
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• 2012

The individual toxicity of lead (Pb) and zinc (Zn) has been investigated by using the sea urchin (Hemicentrotus pulcherrimus) germ cell and pluteus-larvae. The gametotoxic and embryotoxic effects of Pb and Zn on H. pulcherrimus were each investigated at 31, 63, 125, 250, 500 ppb and 16, 31, 63, 125, 250 ppb, respectively. Spawning was induced by 0.5 M KCl solution and the fertilization and normal embryogenesis rates test were performed for 10 min and 64 h after fertilization, respectively. In exposure to Pb, the fertilization rate was not significantly changed compared with control but normal embryogenesis rate was significantly decreased with concentration dependent manner. Fertilization and normal embryogenesis rates showed a significant decreased with concentration dependent manner in exposed to Zn. The normal embryogenesis rates were significantly inhibited in exposed to Pb ($EC_{50}$=45.13 ppb, 95% Cl=40.12~50.05 ppb) and Zn ($EC_{50}$=19.82 ppb, 95% Cl=18.26~21.31 ppb). In exposure to Pb and Zn, the NOEC of normal embryogenesis rate was <31.25 and <15.63 ppb, respectively. The LOEC showed each 31.25 and 15.63 ppb in exposed to Pb and Zn. These results suggest that the early embryo development of H. pulcherrimus is highly sensitive to heavy metals such as Pb and Zn, H. pulcherrimus can be used as a test organism for risk assessment in marine ecosystems.

• Clinical and Experimental Pediatrics
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• v.49 no.1
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• pp.18-23
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• 2006

Purpose : The reliability of hair mineral analyses regarding nutritional status, environmental exposure or diseases is controversial. The aim of this study was to determine the normal reference range of hair mineral concentration of Korean children. Methods : We examined hair mineral concentrations of 223 children(3-12 yrs old, 110 boys, 113 girls, mean age $8.8{\pm}2.2$ yrs old) living in the northern area of Seoul. The trace elements including six toxic elements(Al, As, Cd, Ba, Hg, Pb) and 11 nutritional elements(Na, Mg, P, K, Ca, Cr, Mn, Fe, Cu, Zn, Se) were analyzed by inductive coupled plasma mass spectrometry(ICP-MS). Results : The mean concentrations of Ca and Mg were higher in girls than in boys. The mean concentrations of Cd, Pb and Cr were higher in boys than girls. The Zn, Ca, Mg, Cu and Hg levels in hair samples were positively correlated with increasing age. The Zn levels of the Korean children's hair samples appear to be lower than that of other countries' reference values. Conclusion : There are considerable differences in hair mineral concentrations by age, sex and race. Additional research is needed to establish Korean reference values, and to evaluate the usefulness of hair mineral analyses as a screening tool for nutrition- and environment-related childhood diseases.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.127-138
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• 2014

As increasing concerns about potential risks and hazards in children's products, the laws and regulations for heavy metals and phthalate retardants contained in the children's products have been reinforced in many countries. Especially, in Korea, environment and health laws and regulations for children's products was declared in 2009. This study was researched in terms of contents and migration of phthalates and heavy metals in 124 children's products sold in the Korean market. The results for contents of heavy metals showed that 123 products contained different 14 heavy metals depending on kinds of products. As the results of migration by sucking, the heavy metals in the products such as black, plastic dolls, wood toys, and bottom mat for swimming were transferred into extraction solution. Ba, Cu, Zn, and Sn were transferred from most of these products into the extraction solution and Co, Ni and Pb were additionally transferred into several products. As the results of migration through a skin, while Ba, Cu, and Zn were transferred from most products containing the heavy metals, as for accessories, Cr, Ba, Ni, Zn, and Cu were migrated. The results of contents of phthalates presented that 21 products contained DBP, DEHP and DINP. Only 2 products showed the migration of DEHP by sucking. DEHP in most products were transferred and DBP for 2 products and DINP for 7 products were migrated.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.51-59
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• 2010

The sediments and soils around a mine are likely to be exposed to contamination of arsenic (As) through mining operations. In this study, the factors associated with As movement in soils around a closed zinc (Zn) mine were evaluated by the relationship of As distributions to physico-chemical properties of soils. A sequential extraction scheme, based on a soil P fractionation, was used to assess the As distributionsin solid phases. A significant difference in As distributions was found between paddy and upland soils. While As contents of paddy soils increased with soil depth, those of upland soils decreased with soil depth. In upland soils, As showed additional significant relationships to oxides of Si, Al and Fe. Although a major fraction of As in soils was found to be in the NaOH extractable fraction, As exhibited highly significant relationship to the Zn species that apparently originated from the mine. Therefore, As mobility around Zn mine seems to be governed by mass flow of the particulates containing As-associated Zn in paddy soils, whereas retention reactions such as adsorption, complexation, and precipitation seem to predominate in upland soils.

• Clean Technology
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• v.22 no.2
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• pp.89-95
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• 2016

The nanotoxicity of ZnO nanoparticles used in cosmetics and tire industry is one of emerged issues. Herein, the removal of ZnO nanoparticles dispersed in aqueous phase and its ecotoxicity were investigated. In the short-term exposure for fertilized eggs (O. latipes), the deformity was observed at 5 mg L⁻¹ of ZnO nanoparticles in some individuals and delayed hatching of eggs by retarded growth was observed at 10 mg L⁻¹ of ZnO nanoparticles. This result show that ZnO nanoparticles have cytotoxic effect to the organisms lived in water phase. Therefore, herein, the removal of ZnO nanoparticles in aqueous phase by chemical precipitation was investigated. After addition of Na₂S and Na₂HPO₄, the precipitated ZnO was transformed to ZnS and Zn₃(PO₄)₂ particles, respectively. The removal efficiency of ZnO was reached to almost 100% for two cases. In addition, the toxicity tests about ZnS and Zn₃(PO₄)₂ particles showed no acute toxicity for D. magna. This implies that transformation of ZnO to ZnS and Zn₃(PO₄)₂ particles with very low ionization constant might decrease effectively the toxicity of ZnO.