• Korean Journal of Materials Research
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• v.4 no.8
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• pp.906-914
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• 1994

Plastic behavior of two-phase intermetallic compounds based on $LI_{2}$-type $(Al, Cr)_3$ Ti was investigated using compression test at R.T. and 77K. $LI_{2}$ single phase alloys and two-phase alloys consisting of mainly $LI_{2}$ phase and a few or 20% second phases were selected from AI-Ti-Cr phase diagram. In general, compared with Llz single phase, two-phase alloys consisting of 20% second phase showed relatively high yield strength and poor ductility. Among the alloys, however, AI-21Ti-23Cr alloy consisting of 20% $Cr_{2}Al$ phase showed available ductility as well as high yield strength. Plastic behavior of $LI_{2}$ single phase alloys and two-phase alloys consisting of a few% $Cr_{2}Al$ was also investigated. Homogenization of arc melted ingots substantially reduced the amount of second phases but introduced extensive pore. When Cr content increased in $Ll_{2}$ single phase alloys after the homogenization, the volume fraction of pore in the alloys decreased, and no residual pore was observed in two-phase alloys consisting of a few% $Cr_{2}Al$ phase. Environmental effect on the ductility of the alloys was investigated using compression test at different strain rates($1.2 \times 10^{-4}/s$ and $1.2 \times 10^{-2}/s$). Environmental embrittlement was least significant in A1-25Ti-10Cr alloy consisting of LIZ single phase among the alloys tested in this study. However, based on the combined estimation of the pore formation, environmental embrittlement and ingot cast structure, AI-21Ti-23Cr alloy consisting of 20% $Cr_{2}Al$ as the second phase is expected to show the best tensile elongation behavior.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.1
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• pp.53-64
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• 2020

The Samgwang deposit has been one of the largest deposits in Korea. The deposit consists of series of host rocks including Precambrian metasedimentary rocks and Jurassic Baegunsa formation, which unconformably overlies the Precambrian metasedimentary rocks. The deposit consists of eight lens-shaped quartz veins which filled fractures along fault zones in Precambrian metasedimentary rock, which feature suggest that it is an orogenic-type deposit. Laminated quartz veins are common in the deposit which contain minerals including quartz, ankerite, white mica, chlorite, apatite, rutile, arsenopyrite, sphalerite, chalcopyrite and galena. The structural formulars of white micas from laminated quartz vein and wallrock alteration are determined to be (K_1.02-0.82Na_0.02-0.00Ca_0.00)(Al_1.73-1.58Mg_0.26-0.16Fe_0.23-0.10Mn_0.00Ti_0.03-0.01Cr_0.01-0.00)(Si_3.35-3.22Al_0.79-0.65)O₁₀(OH)₂ and (K_0.75-0.67Na_0.01Ca_0.00) (Al_1.78-1.74Mg_0.16-0.15Fe_0.15-0.13Mn_0.00Ti_0.04-0.02Cr_0.01-0.00)(Si_3.33-3.26Al_0.74-0.67)O₁₀(OH)₂, respectively. It suggest that white mica from laminated quartz vein has higher interlayer cation (K+Na+Ca) and Fe+Mg+Mn+Ti content in octahedral site compared to the white mica from the wallrock alteration. Compositional variations in white mica from laminated quartz vein can be caused by phengitic or Tschermark substitution ((Al³⁺)^VI+(Al³⁺)^IV <-> (Fe²⁺ or Mg²⁺)^VI)+(Si⁴⁺)^IV) and (Fe³⁺)^VI <-> (Al³⁺)^VI substitution. Ankerite from laminated quartz vein has compositional variations of FeO and MgO contents along crystal growth direction. The geochemical and textural features suggest that laminated quartz vein from the Samgwang gold-silver deposit was formed during ductile shear stage, which is an important main gold-silver ore-forming event in orogeinc deposit.

• Journal of Soil and Groundwater Environment
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• v.6 no.4
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• pp.25-40
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• 2001

In order to investigate the degree of heavy metal pollution, 280 urban gully-pot sediments were collected from 13 localities in eastern part of Seoul. The uncontaminated stream sediments were also studied for comparison. A series of studies have carried out concerning the physicochemical characteristics of the sediments and the distribution of Cd, Co, Cr, Cu, Ni, Pb, and Zn. Total metal concentrations of gully-pot sediments and uncontaminated stream sediments were analyzed using acid extraction. After predigestion with $NHO_3$, the sample was digested with mixed acid ($NHO_3$-$HClO_4$). The gully-pot sediments were characterized by very high concentrations of Zn, Cu, Pb and Cr, indicating an anthropogenic contribution of these metals to the sediment chemistry Heavy metal concentrations in the gully-pot sediments were 1-329 times higher than the mean content of metals in the uncontaminated stream sediments, depending on the metals. In particular, the highest mean concentrations of Zn, Cu, Pb and Cr were noticed in the gully-pot sediments from Yeouido, Junggu, Junggu, and Dongdaemungu, respectively. The mean value of total Zn concentration in the business and commercial areas is 2-3.5 times higher than that in industrial areas. This suggests that Zn is mainly derived from automobiles (rubber of automobile tires). The mean concentrations of Cu and Cr are significantly high in the commercial and industrial areas, indicating that industrial activities may cause the accumulation of Cu and Cr in the sediments. The Pb level in gully-pot sediments is comparatively low, due to the use of unleaded gasoline in automobiles since 1987.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.6
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• pp.853-859
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• 2009

Endometriosis becomes the most common cause of pelvic pain and infertility women. The cause of endometriosis has ever been entirely proven. However, an increased use of commercial feminine hygiene products such as tampons and sanitary napkins was considered one of the major affect. Harmful substances in feminine hygiene products was analyzed and evaluated. Samples of commercial products obtained from Korea, Japan, America, Germany, and China were analyzed for six hazardous inorganic elements (chromium, cobalt, nickel, copper, cadmium and lead). In the extractable heavy metals of napkins, Cr, Ni and Cu were found in all of the samples, while Cd was detected only in two samples. In the tampons, Cr, Ni and Cu were found in all of the samples. The presence of Co and Cd was not detected in all samples The concentrations of extractable heavy metals in the tampons were lower than those in the sanitary napkins. The content of extractable heavy metals in the sanitary products was compared with the criteria of the 100 $\ddot{O}KO$ TEX Standard. It was confirmed that the level of heavy metals in the sanitary products posed no serious risk to health, based on the human-ecological criteria defined by the 100 $\ddot{O}KO$ TEX Standard.

• Journal of the Korean institute of surface engineering
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• v.34 no.2
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• pp.89-96
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• 2001

N- or O-doped STS304 stainless films were synthesized by an unbalanced magnetron sputtering process with various argon and reactive gas ($N_2$, $O_2$) mixtures. These films were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), Auger electron spectroscopy (AES) and Knoop microhardness tester. The Results from X-ray diffraction (XRD) analysis showed that a STS304 stainless steel film synthesized without reactive gas using a bulk STS304 stainless steel target had a ferrite bcc structure ($\alpha$ phase), while the N-doped STS304 stainless film was consisted of a nitrogen supersaturated fcc structure, which hsa a strong ${\gamma}$(200) phase. In the O-doped films, oxide Phases ($Fe_2$$O_3$ and $Cr_2$$O_3$) were observed from the films synthesized under an excess $O_2$ flow rate of 9sccm. AES analysis showed that nitrogen content in N-doped films increased as the nitrogen flow rate increased. Approximately 43 at.%N in the N-doped film was measured using a nitrogen flow rate of 8sccm. In O-doped film, approximately 15 at.%O was detected using a $O_2$ flow rate of 12sccm. the Knoop microhardness value of N-doped film using a nitrogen flow rate of 8 sccm was measured to be approximately $H_{ k}$ 1200 and this high value could be attributed to the fine grain size and increased residual stress in the N-doped film.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.939-944
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• 1997

The films of zeolite X on the surface of metal sieve were prepared by continuous crystallization method. It is known that the growth of zeolite crystal on the surface of metal is mainly dependent on the surface composition of metal sieve. In the present work, the zeolite nuclei could be easily formed as Cr content on the metal surface was removed by acid treatment. In order to investigate the proedure growing of zeolite crystal by the continuous crystallization method, the composition of zeolite X($6.36Na_2O-Al_2O_3-5.3SiO_2-190.8H_2O$)was supplied every 12hour. Then the mechanism and inter-relationship between the metal surface and nucleation are investigated. The results show that as the content of silica increases in the gel mixture, the nuclei of zeoilite are easily formed on the metal surface. Also, it was confirmed that the particle of zeolite stuck on the metal surface continues the linear growth. The particles are combined by the reaction of polycondensation, and finally become the shape of crystal. The sample synthesized by the film type was confirmed as zeolite X by the analyses of SEM and XRD.

• Economic and Environmental Geology
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• v.27 no.1
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• pp.29-39
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• 1994

Gabbroic rocks in which titanomagnetite orebodies are embedded were emplaced in Precambrian metasedimentary rocks. Hornblende K-Ar ages for equigranula and gneissic gabbros were obtained to be $1021.8{\pm}14.5$ Ma and $1468.4{\pm}20.8$ Ma, respectively. Biotite-granite has an age of 116.4 Ma, which has corresponded to Daebo granite. Amphibole minerals of the gabbroic rock and the magnetite orebodies belong to calcic amphibole group such as ferroan pargasite, pargasite, and ferro-pargasite. The gabbroic rocks have unusually high content of $TiO_2$ ranging from 0.88 to 6.03 wt.% with an average value of 3.46 wt.% as compared to normal gabbroic rock with 1.32 wt.% in $TiO_2$. Incompatible elements such as Ba and Sr of the gabbros are negatively correlated with $SiO_2$. In contrast, Co and Cr have a positive correlation with $SiO_2$, suggesting a normal differentiation trend of gabbroic magma.

• Korean Journal of Environmental Agriculture
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• v.13 no.3
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• pp.321-337
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• 1994

The garbage from the dwelling houses was composted in two kinds of small composter in laboratory to investigate the possibility of garbage composting. They were general small composters. One (type 1) was insullated but the other (type 2) was not. Because it was found that type 2 was not available for composting under our meteorological conditions through winter experiment, only type 1 was tested in spring and summer. The experiment was performed for 8 weeks in each season. The seasonal variation of several compounds in compost was evaluated and discussed. The result summarized belows are those taken at the end of the experiment, if the time was not specified. 1) The maximum temperature was $58^{\circ}C$ in spring, $57^{\circ}C$ in summer and $41^{\circ}C$ in winter. This temperature was enough to destroy the pathogen except for winter. 2) The mass was reduced to average 62.5% and the volume reduction was avergae 74%. 3) The density was estimated as 0.7kg/l in spring, 0.8kg/l in summer and 1.1kg/l in winter. 4) The water content was not much changed for composting periods. It had 75.6% in spring and 76.6% in summer and winter. 5) There was a great seasonal difference in pH value. It was reached to pH 6.13 in spring, pH 8.62 in summer and pH 4.75 in winter. 6) The faster organic matter was decomposed, the greater ash content was increased. Cellulose and lignin content were increased, but hemicellulose content was reduced during composting period. 7) Nitrogen contents were in the range of 3.1-5.6% and especially high in summer. After ammonium nitrogen contents were increased at the early stage of composting period, they were decreased. The maximum ammonium nitrogen content was 3,243mg/kg after 2 weeks in winter, 6,053mg/kg after 3 weeks in spring and 30,828mg/kg after 6 weeks in summer. C/N-ratios were not much changed. Nitrification occurred actively in spring and summer. 8) The contents of volatile and higher fatty acids were increased in early stage of composting and reduced after that. The maximum content of total fatty acid was 10.1% after 2 weeks in winter, 5.8% after 2 weeks in spring and 15.7% after 4 weeks in summer. 9) The contents of inorganic compounds were not accumulated as composting was proceeded. They were in the range of 0.9-4.4% $P_2O_5$, 1.6-2.9% $K_2O$, 2.4-4.6% CaO and 0.30-0.80% MgO. 10) CN and heavy metal contents did not show any tendency. They were in the range of 0.11-28.99mg/kg CN, 24-166mg/kg Zn, 5-129mg/kg Cu, 0.8-14.3mg/kg Cd, 7-42mg/kg Pb, ND-30mg/kg Cr and $ND-132.16\;{\mu}g/kg$ Hg.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.465-469
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• 2006

Pre-treatment methods to determine various heavy metal contents in packaging papers were investigated by ICP-ES (Inductively Coupled Plasma Emission Spectrometry) analysis. Pre-treatment methods utilized in this study include dry ashing and decomposition methods ($HNO_{3-}HClO_{4-}HF,\;HNO_{3},\;and\;H_{2}SO_{4-}HNO_{3}$). They were compared with the conventional extraction (water) and migration (3% acetic acid) methods. The five representative heavy metals (Cd, As, Pb, Cr and Hg) were analyzed. For Cd, Hg, and As, the results were below detection limit of the instrument. In case of Cr and Pb, the migration test is considered to be a better method compared to the extraction test, but all pretreated methods showed much higher detection efficiency than the extraction or migration test. However, the detection ratio between the migration test and decomposition methods was different. Among all decomposition methods, the nitric acid - perchloric acid - hydrofluoric acid treatment brought a slightly higher detection value than others, but there was no significant difference among them except sulfuric acid - nitric acid method. Concerning Pb, the sulfuric acid - nitric acid method showed a low detection efficiency compared to other decomposition methods. The sulfuric acid - nitric acid method is, thus, not considered to be a suitable analysis method for Pb in packaging papers.

• Environmental Analysis Health and Toxicology
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• v.14 no.4
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• pp.155-163
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• 1999

Heavy metal accumulation in living organisms through food-wed can give serious damage on physiological responses for vital activities. The initiation of heavy metal supposed to begin from the bio-accumulation of plants. To establish basic data fur heavy metal contents in plants at the area without artificial contamination, both woody and herb plants at Mt. Kwang-Duk were studied. The content of heavy metals in various organs of plants were analyzed by ICP. The range of heavy metals in plants for Al, As, Cd, Co, Cr, Cu, Fe. Mn, Pb, Se and Zn were 1.019∼257.200ppm, O∼2.929ppm, 0∼0.079ppm, 0∼0.054ppm, 0.023∼3.007ppm, 0∼1.997ppm, 2.031∼148.500ppm, 1.069∼51.320ppm, O∼126.900ppm, 0.708∼4.927ppm and 0.846∼4.949ppm, respectively. The amount of heavy metals in plants are much less than that of soil except some species. In woody plants, it was detected that the metal contents of leaves were higher than that of stems especially in case of Al and Fe with statistical significance. There were significant differences between shoots and roots of herb plants in metal content of Al, Co and Fe. Those metals have more accumulated in roots comparing with shoots. Some species of plants had shown the difference tendency of heavy metal accumulation. Generally, most species had not exceeded over twice of mean value each other, and had various difference according to the kinds of heavy metals.