• 한국습지학회지
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• 제12권3호
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• pp.15-20
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• 2010

마산만유역의 창원시 수계에서 발생한 오염부하는 차집관로를 통하여 하수종말처리장으로 운반되거나 창원시 하천을 거쳐 봉암갯벌을 경유한 후 마산만으로 유입된다. 즉 마산만 하구 갯벌인 봉암갯벌은 도심에 위치하여 있고 민관산학의 협력으로 보존되어 생태학습장으로 이용되는 귀중한 갯벌이다. 특히 최근 몇 년 동안 조개류, 어류와 물새 등 다양한 생물이 관찰되고 있으며 우리나라 최초의 마산만특별관리해역 연안오염총량관리의 중심 지역에 해당한다. 1970년에 시작한 창원기계공업단지의 가동으로 마산만의 하구와 내만은 중금속으로 오염되었음이 보고되었다. 봉암갯벌의 저서생물의 서식지인 퇴적물에 존재하는 잔류성이 강한 주요 중금속 오염물질의 변화를 분석하였다. 아연, 구리, 납이 오염퇴적물 기준의 상위 기준 또는 심한 오염 기준을 초과하였고 인근 지점 별로도 95% 신뢰구간에서 차이를 보였다. 2006년과 2009년의 자료를 비교할 때 모든 중금속 농도가 점차 감소하고 있었다.

• 대한치과기공학회지
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• 제34권4호
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• pp.337-344
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• 2012

Purpose: This study examined the corrosion level by alloy type and pH, and used the corrosion levels as the dental health data. The study utilized one Ni-Cr alloy for the full and removable partial denture metal frameworks and two Ni-Cr alloys for porcelain-fused-to-metal crown, among the non-beryllium dental casting non-precious Ni-Cr alloys. Methods: The alloy specimens were manufactured in $10cm^2$ and stored in the corrosive solution(pH 2.2-4.4) in the electrical water bath($37^{\circ}C$) for seven days. Afterwards, the metal ions were quantitatively analyzed using the ICP. Results: Of the three metal alloys, Bellabond-Plus$^{(R)}$alloy and SOLIBOND N$^{(R)}$alloy, with 22% or higher chrome chemical contents, had higher corrosion resistance than Jdium-100$^{(R)}$alloy with 20% chrome chemical content. In all three alloys, the corrosion of Ni was highest, and metal ion corrosion was higher in the pH 2.2 corrosive solution. Conclusion: Although Ni-Cr alloy was not very corrosive, a Ni-allergic patient should not have Ni-Cr alloy prosthesis. The Ni-Cr alloy for porcelain-fused-to-metal crown should be designed for the dental porcelain to cover the whole crown.

• Journal of Magnetics
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• 제8권1호
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• pp.1-6
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• 2003

The new class of $Gd_5(Si_xGe_{1-x})_4$ compounds undergoes a simultaneous magnetic/structural phase transition giving a high level of strain that can be induced either by change in temperature or by application of a magnetic field. Profound changes of structural, magnetic, and electronic changes occur in the $Gd_5(Si_xGe_{1-x})_4$ system lead to extreme behavior of the material such as the giant magnetocaloric effect, colossal magnetostriction, and giant magnetoresistance. These unique material characters can be utilized for various applications including magnetic solid refrigerants, sensors, and actuators.

• Journal of Welding and Joining
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• 제16권4호
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• pp.125-135
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• 1998

The shielded metal arc welding (SMAW) by AC power source was performed to evaluate the arc stability by arc monitoring and analysing. In this study, the arc stability index was evaluated quantitatively by using he coefficient of resistance variation for welding time. This coefficient was obtained for the long time (20sec.) by analysing the waveforms of welding current, voltage and resistance. The coefficient was applied to indicate numerically the variation level of arc length and the degree of arc extinction. Using the coefficient of resistance variation in practical welding, the arc stability of the high titanium oxide electrode (KS E4313) turned out to be better than that of the low hydrogen electrode (KS E4316). In evaluating the skill level of welders by the coefficient, the horizontal fillet weaving welding became clear to be very discriminating because the higher level welder could weave in keeping constant arc length, but the lower level welder showed the characteristics of weaving with the unstable arc length. And it was confirmed that the welding defects as blow holes was formed when the arc stability index were high.

• Asian-Australasian Journal of Animal Sciences
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• 제12권4호
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• pp.657-666
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• 1999

The first option in manure management is developing an environmentally sound nutritional management. This includes proper feeding programs and feeds which will result in less excreted nutrients that need to be managed. Critical components that should be controlled are N, P and minerals that are used at supranutritional levels. Amino acid supplementation and protein restriction reduce N excretion in the monogastric animals. Supplementation with enzymes, such as carbohydrases, phytase and proteases, can be used to reduce excretion of nutrients and feces by improving digestibility of specific nutrients. Growth promoting agents, such as antibiotics, beta-agonists and somatotropin, increase the ability of animals to utilize nutrients, especially dietary protein, which results in reduced excretion of N. Some microminerals, such as Cu and Zn, are supplemented at supranutritional level. Metal-amino acid chelates, metal-proteinates and metal-polysaccharide complexes can be used at a much lower level than inorganic forms of metals without compromising performance of animals. Deodorases can be used to avoid air pollution from animal manure. Nutritional management increases costs to implement. It is necessary to assess the economics in order to find an acceptable compromise between the increased costs and the benefits to the environment and production as well.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2001년도 추계학술대회 및 정기총회
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• pp.91-91
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• 2001

Nramp2, also known as DMT1 and DCT1, is a 12-transmembrane domain protein responsible for dietary iron uptake as well as metal ions such as lead, manganese, zinc, copper, nickel, cadmium, and cobalt. High expression of DMT1 increase lead uptake, and DMT1-dependent lead transport was H -dependent and inhibited by iron ions. The molecular mechanism of lead transport in CNS is as yet unknown. although interactions between iron and lead at the level of absorption have been known for some time. The process of lead uptake into astrocytes was not known yet. Nramp2 may mediate transport of heavy metal into astrocytes. We investigated whether Nramp2 mediate transport of lead into astrocytes. And we do whether Nramp2 was expressed highly by deprivation of iron in Astrocytes, and lead uptake into astrocytes was influenced by expression of Nramp2. Immortalized human fetal astrocyte(SV-FHA) cells were cultured in medium containing Dulbecco's modified Eagle's medium and treated with Deferoxamine. Northern blot analysis was done for determining mRNA level of DMT1 and lead uptake assay was done in incubation condition of pH 5.5 and 7.4.

• 한국환경과학회지
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• 제14권6호
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• pp.605-611
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• 2005

The aim of this study was to analyze the local distribution of the heavy metal concentration in Daegu and Ulsan which were divided into the residual areas, the traffic dense areas and the industrial areas. The Inductively Coupled Plasma(ICP) was used to analyze heavy metals, such as As, Cr, Hg, Zn, Cd, Pb, Cu and minor metals, such as Fe, Si, Mg, Ca, AI, Na, K. The results of this analysis showed that the content of heavy metals which was classified by districts in Daegu and Ulsan was the highest in the industrial areas followed by the traffic dense areas and the residual areas. Compared to the level of heavy metals of national and local soil survey network in 2003, contamination of heavy metals in Daegu was lower than national average. However, the content of Cd, As, Zn in Ulsan was respectively 13.38 times, 472 times and 2.65 times higher than national average contamination. In addition, compared to the soil pollution level of the environmental protection law, contamination of all areas in Daegu was lower. But the content of As at the industrial areas in Ulsan was 10.71 times higher than standard of soil pollution and 4.28 times higher than standard of measures against soil contamination.

• 한국환경농학회지
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• 제24권2호
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• pp.106-116
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• 2005

This experiment was conducted to investigate available extraction capacity and potential mobility of heavy metal according to the distribution property and contamination level of heavy metals in soils and to suggest a reform measure of soil environment assessment methodology applied with soil quality and the official soil heavy metal test methods in domestic and foreign countries. The soils were collected from the natural forest paddy with long-term application of same type fertilizer, and paddies near metal mine and industrial complex. The post-treatment methods of soil were partial extraction, acid digestion and sequential extraction methods. For the heavy metal contents with different soil properties, it was shown that their natural forest and paddy soil were slightly low and similar to the general paddy soil, while their paddies near metal mine and industrial complex were higher than the standard level of Soil Environment Protection Act. Heavy metal concentrations in the soils with different soil properties had difference between $HNO_3\;and\;HNO_3+HCl$ extractant by US-EPA 3051a method. There were highly significant positive relationships in both two methods. It was appeared that the higher extractable concentration ratio with 0.1N-HCl to total heavy metal content with $HNO_3+HCl$ extractant the greater total heavy metal content. There were highly significant positive correlationship between total heavy metal content and extractable content with 0.1N-HCl. For extractable capacity of soil extractable solution compared to the total heavy metal content it was appeared that it extractable method with 0.1N-HCl was higher than those with EDTA and DTPA. In extractable ratio with 0.1N-HCl in the contaminated paddy soils near mine and industrial complex, it was shown that the lower soil pH, the higher total heavy metal content. The order of a potential mobility coefficient by distribution of heavy metal content with ie different typies in the soil was Cd>Ni>Zn>Cu>Pb. It could be known that contamination characteristics of heavy metals with different types of soils were affected by different heavy metal components, contamination degree and soil chemical properties, and heavy metal concentration with different extractable methods had great variations with adjacent environment. To be compared with assessment methodology of soil environment impact at domestic and foreign countries with our results, it might be considered that there was necessary to make a single analysis method based on total heavy metal content with environmental overloading concept because of various analysis methods for total heavy metal content and present analysis method with great variation according to soil environment. In spite of showing higher concentration of heavy metal with acidic digestion than the extractable method, it might be considered that there is need to be adjusted the national standard of soil heavy metal contamination.

• The Journal of Advanced Prosthodontics
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• 제12권3호
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• pp.124-130
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• 2020

PURPOSE. The aim of this in vitro study was to evaluate the effect of sintering procedures on marginal discrepancies of fixed partial metal frameworks fabricated using different sintering-based computer-aided design and computer/aided manufacturing (CAD/CAM) techniques. MATERIALS AND METHODS. Forty resin die models of prepared premolar and molar abutment teeth were fabricated using a three-dimensional (3D) printer and divided into four groups (n = 10) according to the fabrication method of metal frameworks used: HM (via hard milling), SM (via soft metal milling), L25 (via direct metal laser melting [DMLM] with a 25 ㎛ layer thickness), and L50 (via direct DMLM with a 50 ㎛ layer thickness). After the metal frameworks were fabricated and cemented, five vertical marginal discrepancy measurements were recorded in each site (i.e., buccal, facing the pontic, lingual, and facing away from the pontic) of both abutment teeth under a stereomicroscope (×40). Data were statistically analyzed at a significance level of 0.05. RESULTS. No statistically significant differences (P>.05) were found among the four axial sites of metal frameworks fabricated by sintering-based CAD/CAM techniques. The HM and L25 groups showed significantly (P<.001) lower marginal discrepancy values than the SM and L50 groups. CONCLUSION. Marginal discrepancy in the sites facing the pontic was not influenced by the type of sintering procedure. All fabrication methods exhibited clinically acceptable results in terms of marginal discrepancies.

• 대한족부족관절학회지
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• 제18권2호
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• pp.68-71
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• 2014

Purpose: The purpose of this study is to report the results of culture test at the time of removal of metal devices used for management of ankle fractures and for analysis of contributing factors. Materials and Methods: We reviewed medical records of 132 patients with lower tibia and ankle fracture who had their metal devices removed during the period from January 2010 to February 2014. Patients with clinical signs of infection were excluded. Culture test was performed by taking the granulation tissue around the metal device at the time of removal. We divided the subjects into two groups, culture positive and negative. We then performed a retrospective review of each medical record of multiple factors that might contribute to the culture results, including laboratory results, medical history, material and size of metal device, indwelling period, and whether or not it was open injury. Results: Among 132 cases, six were culture positive. Enterococcus was detected in two cases and the others were Staphylococcus. No significant difference in medical history of patients and laboratory results, including C-reactive protein level, was observed between the culture positive and negative group. Culture positive rate was 5.4% in titanium and 3.9% in stainless steel. In terms of metal size, culture positive rate was 5.1% in small plates, 6.7% in large plates, and culture negative in intramedullary nails. The average indwelling period of metal device was 61.5 weeks in the culture positive group, and 68.6 weeks in the negative group. Nine cases were open fractures and all were in the culture negative group. Conclusion: Whether or not the culture result was positive, there were no meaningful contributing factors. Presence of bacterium on the metal device could not be screened by any laboratory results or other factors.