• Analytical Science and Technology
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• v.11 no.1
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• pp.29-35
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• 1998

This study was performed to assess the levels of the Cr and Co in fisheries caught from the some areas of west coast in Korea. The samples were 26 kinds of fishes, 19 kindly of Mollusca and 3 kinds of Crustacea. They were ashed with 5 ml $HNO_3$ and then wet-decomposed with 10 ml of a mixture of $HNO_3:H_2SO_4:HClO_4$ (10:1:4). After ashing of samples, the amounts of Cr and Co in the samples were determined by ICP-AES analysis. The moisture content of molluscans was significantly higher than that of crustaceans (p<0.05), but there was no significant difference among fisheries in the Cr content. And the Co content of crustaceans was significantly higher than that of fishes and molluscans (p<0.001). There was no significance between contents of Cr and Co in fisheries. The Cr content of Arkshell was 422.00 ppm, which was the most amount compared with those of the other samples. And the Co in Myong-Ge was 3.78 ppm, which was the most amount. Areliscus honaleus (Cr:2.76 ppm, Co:0.97 ppm), Solen (Cr:6.56 ppm, Co:1.59 ppm) and dried barley shrimp (Cr:1.06 ppm, Co:0.90 ppm) contained great amount of Cr and Co.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.131-140
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• 2000

Heavy metals (Fe, Mn, Cr, Co, Cu, Ni, Zn, Pb) were determined in ninety-one surface sediments collected from Kwangyang Bay, south coast of Korea. The data show that the Fe, Cr, Ni, and Zn distribution in the bay can be described by metal vs. grain size relationship. However, the distribution pattern of Mn, Co, Cu and Pb were found to be changed because they are anthropogenically enriched to sediment. Correlation matrix and R-mode factor analyses revealed that two important factors controlling the distribution of metals in the bay are grain size and anthropogenic input.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.2
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• pp.248-260
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• 2021

Cobalt-chromium alloys are used to fabricate various dental prostheses, and have advantages of low cost and excellent mechanical properties compared to other alloys. Recently, selective laser melting, which is an additive manufacturing method, has been used to overcome the disadvantages of the conventional fabrication method. A local rapid heating and cooling process of selective laser melting induces fine microstructures, grain refinement, and reduction of porosities of the alloys. Therefore, it can improve mechanical properties compared to the alloys fabricated by the conventional method. On the other hand, layering process and rapid heating and cooling cause accumulation of a large amount of residual stresses that can adversely affect the mechanical properties. A heat treatment for removing residual stresses through recovery and recrystallization process caused complicated changes in mechanical properties induced by phase transformation, precipitate and homogenization of the microstructures. The purpose of this review was to compare the manufacturing methods of Co-Cr alloys and to investigate the characteristics of Co-Cr alloys fabricated by selective laser melting.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.6
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• pp.455-463
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• 2009

코발트 보호막 코팅이 적용된 페라이트계 스테인리스 스틸인 STS 430과 STS 444 소재에 대해 고체산화물 연료전지용 금속연결재로서의 고온 산화 특성에 대해 살펴보았다. 코발트 코팅층은 $800^{\circ}C$ 고온 산화 후 코발트 산화물 및 $Co_2CrO_4$, $CoCr_2O_4$, $CoCrFeO_4$ 등과 같은 코발트가 함유된 스피넬 상을 형성하였다. 또한 페라이트계 스테인리스 스틸과 코발트 코팅의 계면에서 크롬과 철이 함유된 치밀한 산화층을 형성하여 금속연결재 표면의 스케일 성장속도를 감소시키고 금속연결재 내에 함유된 크롬의 외부 확산을 효과적으로 억제하였다. 한편 STS 430은 고온 산화 후 표면에 형성된 스케일 하부에 $SiO_2$와 같은 내부 산화물이 형성된 반면 STS 444는 표면 스케일 이외에 다른 내부 산화물은 확인되지 않았으며 고온에서의 면저항 측정 결과, 코발트가 코팅된 STS 444의 전기 전도성이 STS 430 보다 우수한 것으로 나타났다.

• Journal of dental hygiene science
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• v.15 no.5
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• pp.536-541
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• 2015

The purpose of this study was to evaluate the marginal and internal gap of Cobalt (Co)-Chromium (Cr) sintering metal coping fabricated by dental computer-aided design/computer-aided manufacturing systems. Abutment tooth 46 of universal numbering system was selected for the study. Twenty Co-Cr metal copings of two groups were manufactured and scanned. Co-Cr cast metal copings (CCM) group of ten were fabricated using investment, burnout and casing after subtractive manufacturing of wax block. Also, Co-Cr sintering metal copings (CSM) group of ten were fabricated using sintering processing after subtractive manufacturing of Co-Cr soft metal bock. Marginal and internal gap of Co-Cr metal copings of twenty were measured by digital microscope (${\times}160$) with silicone replica technique. The data was analyzed from IBM SPSS Statistics ver. 22.0 Statistical software for Mann-Whitney U test (${\alpha}=0.05$). $Mean{\pm}standard$ deviation of marginal gap of CCM group was $90.12{\pm}61.73{\mu}m$ of CSM group was $60.17{\pm}24.83{\mu}m$. However, two groups was statistically not different (p>0.05). This study showed that CSM group was clinically acceptable adaptation.

• 대한치과보철학회:학술대회논문집
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• 1999.11a
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• pp.70-70
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• 1999

• 대한치과보철학회:학술대회논문집
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• 1999.11a
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• pp.72-72
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• 1999

• The Journal of the Korean dental association
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• v.27 no.5 s.240
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• pp.467-471
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• 1989

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.1
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• pp.73-79
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• 2011

Purpose of this experiment is to evaluate the effect of titanium on the castability when the titanium is added to the Co-Cr alloy. Raw materials Cobalt, Chrome, Molybdenum, Silicon, Manganase, Carbon, Nitrogen, Titanium were weighted and prepared. $Biosil^F$ (Degudent, Germany) was the control group. To the experimental group, different weight percent of titanium was added from 1 wt% to 4 wt%. The wax pattern is $30{\times}40$ cm in size, rectangular in shape and has total of 160 grids. Centrifugal machine (Neutrodyne Easy Ti: Manfredy) was used for casting. For evaluation of the castability, the number of complete grids was counted by visual inspection and X-ray inspection. The test showed similar castability with the control group in the titanium addition of 1 wt% to 3 wt%. The titanium addition of 4 wt% showed poor result. With titanium lower than 4 wt%, the experiment metals showed proper castability with high expectation of successful clinical use.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.50 no.1
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• pp.77-84
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• 2024

Four children's cosmetic sets were purchased online, labeled for use from 4 years of age, and 81 components of each were analyzed for lead, cadmium, arsenic, antimony, nickel, cobalt, copper, chromium, and mercury by inductive coupled plasma - mass spectrometry (ICP - MS). The average metal concentrations were as follows: 0.82 ㎍/g for lead, 0.03 ㎍/g for cadmium, 0.97 ㎍/g for arsenic, 0.52 ㎍/g for antimony, 2.32 ㎍/g for nickel and 0.01 ㎍/g for mercury which was lower than the acceptable standards for all products. Higher mean values of lead, antimony, cobalt, and copper were detected in imported than domestic products (p < 0.05). There was a statistically significant difference in the average values of heavy metals according to the type of cosmetics (p < 0.05), with eyeshadow showing the highest mean values of arsenic 2.47 ㎍/g, nickel 6.36 ㎍/g, and chromium 11.06 ㎍/g. and the highest mean concentrations were 1.20 ㎍/g for lead, 1.17 ㎍/g for antimony, and 23.60 ㎍/g for copper in blusher. The levels of cobalt in the 81 children's cosmetics were ND ~ 5.23 ㎍/g, copper were ND ~ 379.61 ㎍/g, and chromium were detected ND ~ 36.95 ㎍/g, respectively. Brown colored cosmetics had the highest mean concentrations of nickel and cobalt. Purple-colored cosmetics had the highest mean concentration of lead and chromium.