• Journal of Food Hygiene and Safety
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• v.3 no.1
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• pp.7-18
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• 1988

In 1987, the level of heavy metals were determined ina total of 200 samples of 9 species of shellfish of Korea. The samples were collected at the fish. markets by 10 Public Institute of Health. The samples were whelk (Buccinum striatiBBimum), oyster (Crassostrea gigas), ark shell(Tegillarca granesa), shartnecked clam (Venerupis semidecussta), hard clam (Meretrix lusoria), top shell (Turbo cornutus), abalone (Haliotis gigantea), ark shell (Scapharea broughtonii), sea-mussel (Mytilus conuscus gould), respectively. The levels of total mercury, lead, cadmium, arsenic, copper, zinc and manganese were determined. The total mercury levels were determined by mercury analyzer using the combustion gold amalgamation method. The arsenic level were determined by spectrophotometry using colorimetric sil ver diethyldithiocarbamate method after dry ash dige8tion of the samples with magnesium oxide and magnesium nitrate. The levels of other metals were determined by inductively coupled pluma spectrophotometry after wet digestion of the samples with nitric acid and su1furic acid. The results were summerized as follows; 1. The overallranges and mean(ppm) were; Hg, ND-O.221 (0.036); Pb, 0.05-1.51 (0.37); Cd, 0.02-1.86 (0.61); As, 0.5-3.97 (1.22); Cu, 0.14-54.16 (4.93); Zn, 7.40-207.17 (30.09); Mn, 0.13-s.72 (3.40). 2. The levels of all 6 metals were found to be below the maximum permissible Iimits set by the Japan lor mercury, the Netherland for lead the Hong Kong for cadmium. The Finland for Arsenic no statutory Iimits for Zn and Mn in shellfish in any countries. 3. The results show that all the 9 species of shellfish studied, none have accumulated levels dangerous enough to pose a health problem.roblem.

• Journal of Korean Society of Forest Science
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• v.88 no.4
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• pp.510-522
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• 1999

The air pollutants ; $SO_2$, $SO{_4}^{-2}$, $NO{_3}^-$, $Cl^-$ are absorbed into soils through falling with dusts and rain from the atmosphere. The sources of heavy metal contaminants in the environments are agricultural and horticultural materials, sewage sludges, fossil fuel combustion, metallurgical industries, electronics and waste disposal etc.. The soils and hydrosphere can be polluted on the way of the circulation of these heavy metals. Studied pollutant anions are $SO{_4}^{-2}$, $NO{_3}^-$ and $Cl^-$ and heavy metals are Se, Mo, Zn, Cd, Pb, Mn, Cr, Co, V, As, Cu and Ni which are the elements to be concerned with the essentials for plants, with animal and human health. This study is with the aim of selecting the species of roadside trees and green space trees which have excellent absorption of air pollutants and heavy metals from the atmosphere and the soils in the urban area. Two areas are designated to carry out this study : urban area ; Kwangju city and rural area ; the yard of Forest Environment Institute of Chollanam-do, at Sanje-ri, Sampo-myum, Naju city, Chollanam-do (23km away from Kwangju). This study is carried out to understand the movement of anions and heavy metals from the soils to the trees in both areas, the absorption of anions and heavy metals from atmosphere into leaves and the amounts of anions and heavy metals in leaves and fine roots(< 1mm dia.) of roadside trees and green space trees in Kwangju and trees in the yard of Forest Environment Institute of Chollanam-do. The tree species selected for this study in both areas are Ginkgo biloba, Quercus acutissima, Cedrus deodara, Platanus occidentalis, Robinia pseudoacacia, Alnus japonica. Metasequoia glyptostroboides. Zekova serrata. Prunus serrulata var. spontanea, and Pinus densiflora. The results of the study are as follows : 1. $SO{_4}^{-2}$, $NO{_3}^-$ and $Cl^-$ concentrations are higher in the soils of the urban area than in those of the rural area, and $NO{_3}^-$ and $SO{_4}^{-2}$ are higher in the leaves than in the roots due to the absorption of the these pollutants through the stomata. 2. Ginkgo biloba, Robinia pseudoacacia. Zekova serrata, Quercus acutissima, and Platanus occidentalis can be adequated to the roadside trees and the environmental trees due to their good absorption of $NO{_3}^-$ and $SO{_4}^{-2}$. 3. Heavy metals in the soils of both areas are in the order of Mn > Zn > V > Cr > Pb > Ni > Cu > Mo> Cd, and in the leaves and roots of the trees in the both areas are in the order of Mn>Zn>Cr>Cu>V>Ni. Both orders are similar ones except V. There are more in the urban soils than in the rural soils in amount of Mn, Zn, Pb, V, Cu. 4. It is supposed that there is no antagonism between Mn and Zn in this study. 5. Se, Co and As are not detected in the soils, the leaves and the roots in both areas. Sn, Mo, Cd and Pb are also not detected in the leaves and roots in spite of considerable amount in the soils of both areas.

• Tribology and Lubricants
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• v.30 no.6
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• pp.330-336
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• 2014

Sintered metallic brake pads and low alloy heat resistance steel disks are applied to mechanical brake systems in high energy moving machines that are associated with recently developed 200km/h trains. This has led to the speed-up of conventional urban rapid transit. In this study, we use a lab-scale dynamometer to investigate the effects of the composition of friction materials on the tribological characteristics of sintered metallic brake pads and low alloy heat resistance steel under dry sliding conditions. We conduct test under a continuous pressure of 5.5 MPa at various speeds. To determine the optimal composition of friction materials for 200 km/h train, we test and the evaluate frictional characteristics such as friction coefficients, friction stability, wear rate, and the temperature of friction material, which depend on the relative composition of the Cu-Sn and Fe components. The results clearly demonstrate that the average friction coefficient is lower for all speed conditions, when a large quantity of iron power is added. The specimen of 25 wt% iron powder that was added decreased the wear of the friction materials and the roughness of the disc surface. However when 35 wt% iron powder was added, the disc roughness and the wear rate of friction materials increased By increasing the amount of iron powder, the surface roughness, and temperature of the friction materials increased, so the average friction coefficients decreased. An oxidation layer of $Fe_2O_3$ was formed on both friction surfaces.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.177-193
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• 2009

The Samgwang deposit consists of eight massive mesothermal quartz veins that filled NE and NW-striking fractures along fault zones in Precambrian granitic gneiss of the Gyeonggi massif. The mineralogy and paragenesis of the veins allow two separate discrete mineralization episodes(stage I=quartz and calcite stage, stage II-calcite stage) to be recognized, temporally separated by a major faulting event. The ore minerals are contained within quartz and calcite associated with fracturing and healing of veins that occurred during both mineralization episodes. The hydrothermal alteration of stage I is sericitization, chloritization, carbonitization, pyritization, silicification and argillization. Sericitic zone occurs near and at quartz vein and include mainly sericite, quartz, and minor illite, carbonates and chlorite. Chloritic zone occurs far from quartz vein and is composed of mainly chlorite, quartz and minor sericite, carbonates and epidote. Fe/(Fe+Mg) ratios of sericite and chlorite range 0.45 to 0.50(0.48$\pm$0.02) and 0.74 to 0.81(0.77$\pm$0.03), and belong to muscovite-petzite series and brunsvigite, respectiveIy. Calculated $Al_{IV}$-FE/(FE+Mg) diagrams of sericite and chlorite suggest that this can be a reliable indicator of alteration temperature in Au-Ag deposits. Calculated activities of chlorite end member are $a3(Fe_5Al_2Si_3O_{10}(OH)_6$=0.0275${\sim}$0.0413, $a2(Mg_5Al_2Si_3O_{10}(OH)_6$=1.18E-10${\sim}$7.79E-7, $a1(Mg_6Si_4O_{10}(OH)_6$=4.92E-10${\sim}$9.29E-7. It suggest that chlorite from the Samgwang deposit is iron-rich chlorite formed due to decreasing temperature from high temperature(T>450$^{\circ}C$). Calculated ${\alpha}Na^+$, ${\alpha}K^+$, ${\alpha}Ca^{2+}$, ${\alpha}Mg^{2+}$ and pH values during wallrock alteration are 0.0476($400^{\circ}C$), 0.0863($350^{\circ}C$), 0.0154($400^{\circ}C$), 0.0231($350^{\circ}C$), 2.42E-11($400^{\circ}C$), 7.07E-10($350^{\circ}C$), 1.59E-12($400^{\circ}C$), 1.77E-11($350^{\circ}C$), 5.4${\sim}$6.4($400^{\circ}C$), 5.3${\sim}$5.7($350^{\circ}C$)respectively. Gain elements(enrichment elements) during wallrock alteration are $TiO_2$, $Fe_2O_3(T)$,CaO, MnO, MgO, As, Ag, Cu, Zn, Ni, Co, W, V, Br, Cs, Rb, Sc, Bi, Nb, Sb, Se, Sn and Lu. Elements(Ag, As, Zn, Sc, Sb, Rb, S, $CO_2$) represents a potential tools for exploration in mesothermal and epithermal gold-silver deposits.

• Journal of the Mineralogical Society of Korea
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• v.25 no.1
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• pp.41-50
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• 2012

페루 남동부 지역에 위치한 꾸스코 동-금을 포함한 다중금속 광상 지역의 지질은 고생대 페름기-중생대 삼첩기 변성퇴적암인 미투(Mitu)층군과 이를 관입한 동시기 관입암으로 구성되어 있다. 조사지역은 페름기-삼첩기 관입암과 관련된 U-W-Sn-Mo, Au-Cu-Pb-Zn, REE 광화작용과 관련된 금속광화 대로 알려져 있다. 특히 해당 관입암은 대자율 측정 결과 S-type, 티탄철석계열과 관련이 있는 것으로 보인다. 꾸스코 지역은 깔까 북쪽과 시꾸아니 부근에 주요 광화대가 발달하고 있다. 조사대상 광상은 아줄 동, 올미오 동, 빅토리아 금, 빠딴자 동, 나우챠피-초차까나 동, 체카 금광상이다. 아줄 광상의 모암은 안산암질암이며 광석광물로는 반동석 및 황동석이 산출하며, 동은 7.81~15.3%의 범위를 가지고 평균 10.7%이다. 올미오 광상의 모암은 흑색편암이며 엽리를 따라 산화동이 충진되어 있고, 동은 0.61~2.60%의 범위를 가지고 평균 1.74%이다. 빅토리아 광상의 모암은 변성퇴적암이며, 석영맥 충진형 광상으로 금함량은 < 0.1 g/t, 은함량은 < 0.1~< 0.3 g/t이다. 빠딴자 광상에서는 이암 또는 실트암의 층리를 따라 충진하고 있는 산화동이 산출하며, 동은 3.74~9.21%의 범위를 보이며 평균 6.21%이다. 나우챠피-초차까나 광상은 적색사암의 층리를 교대충진하고 있는 산화동 광체이며, 동은 1.62~10.5%의 범위를 가지며 평균 6.39%이다. 체카 광상은 모암인 규암이 각력화작용을 받은 부분에서 금이 산출되고 있는 것으로 보고되어있으나 분석결과 금이 탐지되지는 않았다.

• Journal of radiological science and technology
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• v.42 no.6
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• pp.429-434
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• 2019

The gonads are directly affected by radiation exposure during radiography of the pelvis, abdomen, and spine. Exposure of the gonads to radiation can cause genetic mutations and can result in the occurrence of malignant tumors. In this study, we created three types of shielding material shapes for shielding of the ovaries, which are the gonads of female during radiography of the pelvis, and comparative evaluations using shadow shielding methods. The source surface distance(SSD) was 100 cm and the field size was 42 cm × 43 cm. The three types of shielding material shapes(type 1, 2 and 3) were assessed and the entrance surface dose in the ovaries were measured. The thickness of the shielding material was expanded from 0.3 mm to 2.4 mm and after five repetitions, radiation values were measured and mean values were calculated. The mean dose were 3.09 mGy for type 1, 3.54 mGy for type 2, and 3.19 mGy for type 3, indicating that the measurements were the lowest for type 1. When an additional filter of 0.2 Cu + 1 Al was used, the dose were 3.72 mGy for type 1, 5.43 mGy for type 2, and 4.05 mGy for type 3, indicating that the measurements were the lowest for type 1. The results show that, even if the shielding material is not thick, in other words, even with a thickness of 2.94 mGy for the SN 3(0.9 mm) of type 1, shielding can be achieved, with a patient dose lower than the diagnostic reference level(3.42 mGy). Additionally, among the three types of shielding material, the type 1 appeared to be the most appropriate shielding material. It is thought that the use of shielding material could reduce the risk factors for stochastic effects or critical effects of ionizing radiation during pelvic or lumbar radiography.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.745-764
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• 2023

In the Republic of Congo, Banded iron formations (BIFs) occur in two areas: the Chaillu Massif and the Ivindo Basement Complex, which are segments of the Archean Congo craton outcropping in the northwestern and southwestern parts of the country. They show interesting potential with significant mineral resources reaching 2 Bt and grades up to 60% Fe. BIFs consist mostly of oxide-rich facies (hematite/magnetite), but carbonate-rich facies are also highlighted. They are found across the country within the similar geological sequences composed of amphibolites, gneisses and greenschists. The Post-Archean Australian Shale (PAAS)-normalized patterns of BIFs show enrichment in elements such as SiO₂, Fe₂O₃, CaO, P₂O₅, Cr, Cu, Zn, Nb, Hf, U and depletion in TiO₂, Al₂O₃, MgO, Na₂O, K₂O, Sc, Th, Ba, Zr, Rb, Ni, V. REE diagrams show slight light REEs (rare earth elements; LREEs) compared to heavy REEs (HREEs), and positive La and Eu anomalies. The lithological associations, as well as the very high (Eu/Eu^*)_SN ratios> 1.8 shown by the BIFs, suggest that they are related to Algoma-type BIFs. The positive correlations between Zr and TiO₂, Al₂O₃, Hf suggest that the contamination comes mainly from felsic rocks, while the absence of correlations between MgO and Cr, Ni argues for negligeable contributions from mafic sources. Pr/Pr^* vs. Ce/Ce^* diagram indicates that the Congolese BIFs were formed in basins with redox heterogeneity, which varies from suboxic to anoxic and from oxic to anoxic conditions. They were formed through hydrothermal vents in the seawater, with relatively low proportions of detrital inputs derived from igneous sources through continental weathering. Some Congolese BIFs show high contents in Cr, Ni and Cu, which suggest that iron (Fe) and silicon (Si) have been leached through hydrothermal processes associated with submarine volcanism. We discussed their tectonic setting and depositional environment and proposed that they were deposited in extensional back-arc basins, which also recorded hydrothermal vent fluids.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.1
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• pp.33-38
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• 2001

We investigate the via-size dependance of as-electroplated- and reflow-bump shapes for realizing both high-density and high-aspect ratio of solder bump. The solder bump is fabricated by subsequent processes as follows. After sputtering a TiW/Al electrode on a 5-inch Si-wafer, a thick photoresist for via formation it obtained by multiple-codling method and then vias with various diameters are defined by a conventional photolithography technique using a contact alinger with an I-line source. After via formation the under ball metallurgy (UBM) structure with Ti-adhesion and Cu-seed layers is sputtered on a sample. Cu-layer and Sn/pb-layer with a competition ratio of 6 to 4 are electroplated by a selective electroplating method. The reflow-bump diameters at bottom are unchanged, compared with as-electroplated diameters. As-electroplated- and reflow-bump shapes, however, depend significantly on the via size. The heights of as-electroplated and reflow bumps increase with the larger cia, while the aspect ratio of bump decreases. The nearest bumps may be touched by decreasing the bump pitch in order to obtain high-density bump. The touching between the nearest bumps occurs during the overplating procedure rather than the reflowing procedure because the mushroom diameter formed by overplating is larger than the reflow-bump diameter. The arrangement as zig-zag rows can be effective for realizing the flip-chip-interconnect bump with both high-density and high-aspect ratio.

• Resources Recycling
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• v.26 no.6
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• pp.84-90
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• 2017

The electro-refining process was performed to recovery high purity copper from low grade copper containing sludge in sulfuric acid. The surface morphologies and roughness of electro-refining copper were analyzed with variation of the type and concentration of organic additives, the best surface morphology was obtained 5 ppm of the gelatin type and 5 to 10 ppm of the thiol type organic additive. The crude metal consisted of copper with 86.635, 94.969 and 99.917 wt.%, several impurity metals of iron, nickel, cobalt and tin by pyro-metallurgical process. After electro-refining process, the purity of copper increases to 3N or 4N grade. The impurity concentrations and copper purities of copper crude metals, electrolyte and electro-refining copper were analyzed using ICP-OES, the electro-refining time and purity of copper crude metal to recover 4N grade copper were deduced.

• Journal of Environmental Health Sciences
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• v.49 no.2
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• pp.66-77
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• 2023

Background: Along with the increase in consumer interest in and consumption of tattoo products, the controversy over harmful heavy metals associated with the use of tattoo cosmetics is also increasing. Therefore, investigation of hazardous metals in these tattoo products is needed. Objectives: This study was performed to provide useful data for establishing reasonable standards to securely manage tattoo cosmetics, tattoo stickers, and tattoo inks distributed in the market. Methods: Thirteen kinds of hazardous metal contents (Pb, As, Cd, Sb, Ni, Co, Cu, Cr, Se, Ba, Zn, Sn, and Hg) were analyzed for 23 tattoo cosmetics, ten tattoo stickers, and 16 tattoo inks. Hg was measured through the combustion-gold amalgamation method, and other hazardous metals were measured by inductively coupled plasma-mass spectrometry (ICP-MS) after acidic decomposition using a microwave apparatus. Results: The detected ranges of Pb, As, Cd, Sb, Ni, and Hg in tattoo cosmetics were 0.07~1.18, 0.06~0.41, ND~0.07, 0.01~3.44, 0.12~2.75, and ND~0.01 ㎍/g, respectively. All of the hazardous metals detected were below the recommended maximum standards of the Ministry of Food and Drug Safety. The mean amount of Pb detected in tattoo stickers for children was 0.24 ㎍/kg and Cd was not detected, meaning both metals met the recommended criteria. There was no statistically significant difference in all measured metals between children's tattoo stickers and adults' tattoo stickers. In the results of the study on the hazardous metal content of tattoo inks, four products (25%) for Pb, one product (6%) for As, 13 products (81%) for Ni, four products (25%) for Cu, and five products (31%) for Zn exceeded the recommended standards approved by the government. The highest predicted exposure amount for hazardous metals exceeding the recommended level of tattoo inks in a single tattooing was 5.69 ㎍/kg for Ni, 8.51 ㎍/kg for Zn, 0.44 ㎍/kg for Pb, 8.07 ㎍/kg for Cu, 0.44 ㎍/kg for As, and 71.36 ㎍/kg for Ba. Conclusions: It is necessary to prepare criteria for content limitation for the management of Co, Cr, Ba and Se tattoo cosmetics, and tattoo inks require thorough quality control.