• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.423-432
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• 1986

Atomic absorption spectrophotometric (AAS) determination of hexavalent chromium [Cr(VI)] in a waste water was studied. Cr(VI) was extracted with p-xylene from the wastewater, in the way of ion pair formation with anion exchanger aliquat-336(tri-caprylmethyl ammonium chloride). 100ml waste water, after organic materials were extracted out with toluene, was acidified with conc. HCl adjusting the medium to pH 0.5 and 20ml of p-xylene containing 0.01M aliguat-336 was used to extract Cr(VI) from the acidified solution. The absorbance of chromium was measured with air-acetylene flame at 357.9nm. Standard addition method was used in the determining concentration of Cr(VI) extracted. No interference has been found in the extraction of Cr(VI) by the Al(III), Fe(III) and Cr(III) ion presented. However, Fe(II) decreased the absorbance of Cr(VI), due to the fact Fe(II) reduces Cr(VI) to Cr(III). The contained organic material was removed prior to extracting process, since it may reduced the absorbance of Cr(VI). The recovery of added Cr(VI) was over 96%, which seems to be promising and the relative standard deviation was 3.95%

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.207-207
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• 2015

국내 자동차메이커는 디자인고급화를 위하여 08년 이후 다양한 표면처리를 적용하고 있다. 특히 외장부품은 다크크롬, 짙은크롬, 반광등은 코드화 작업을 마쳤다. 2010년이후에는 겨울철 제설염으로 인한 6가크롬도금의 취약성을 발견하고 2011년 제설염 테스트 규격개정을 작업을 완료하였으며, 2015년이후 출시 차량은 6가크롬은 삭제하였으며, 3가크롬도금으로 큰 전환이 일어났다. 또한 라디에이타그릴은 대형화흐름으로 기존의 $50dm^2$이하의 디자인이 $100dm^2$이상 디자인으로 변경하는 추세이다. 이러한 변화에 도금공장은 기존라인으로 생산이 어려워 신규LINE 증설로 대응하고 있으나, 불량의 증가로 채산성이 악화되고 있다.

• Journal of the Korean institute of surface engineering
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• v.11 no.1
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• pp.22-25
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• 1978

老化크로미이트液中의 3가크롬을 6가크롬으로 酸化處理하여 크롬의 完全한 有效活用을 도첩한 化학的 酸化處理方式에 의한 크로메이트의 再生시스템에 관하여 기술하고자 한다.

• Journal of the Korean GEO-environmental Society
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• v.10 no.4
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• pp.25-31
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• 2009

In this study, the problem of existing soil pavement is a long-term durability lack and crack occurrence. It complements in order to develop the environmental soil pavement material which composites readily blended mineral binder of liquid and decomposed granite soils. It was estimated optimal mixture proportion for unconfined compressive strength, permeability, $Cr^{6+}$detection test, SEM test with age, freezing and thawing test. It resulted mixture proportion of powder types mineral binder for rates of cement : fly ash : plaster was optimal rates of 50 : 33 : 7, and $Cr^{6+}$detection test as a result was a slight production. SEM test with 3days as a result was made Ettringite. It was found that this material was early development of early-strength for chemical. This study indicated that it will execute field appliciability Evaluation test, examination of soil pavement method with decomposed granite soils and mineral binder.

• Korean Journal of Environmental Biology
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• v.24 no.1 s.61
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• pp.38-45
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• 2006

Ecological characteristics of microbial populations inhabiting heavy metal polluted soil were investigated. The samples were collected from 293 sites around an factory and industry at Gyeoungsangbuk-do. We measured the contents of seven heavy metal elements (Cd, Cu, As, Hg, Pb, $Cr^{6+}$, CN), seven sites have been seriously contaminated by mercury and chrome. A quantitative evaluation of microbial populations in mercury and chrome contaminated soil was examined by using plate count method. Bacterial numbers in polluted soil samples ranged from $7.4X10^5\;to\;9.3X10^7\;cfu\;g^{-1}$, about $10\sim100$ fold less than the count for the unpolluted soil. Moulds were not detected in chrome polluted soil. The log values of actinomycetes of each contaminated soil samples were log ranged from 6.18 to 7.52. The ratio of actinomycetes was similar to unpolluted soil. The investigation showed actinomycetes to be the major microbial population inhabiting the mercury and chrome polluted soil. Thirty-one isolates among the total isolates were examined for antibacterial activity. These isolates were identified based on a phylogenetic analysis using 16S rRNA gene nucleotide sequences, they were categorized in three major phylogenetic groups, belong to the Streptomyces (6 strains), Saccharopolyspora (3 strains), Nocardiodes (1 strain). On the phylogenetic tree, the clade consisting of five isolates were distantly related to all of the established Streptomycetes genera, indicating the possibility as members of new species.

• Cement Symposium
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• no.32
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• pp.192-197
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• 2005

• Cement Symposium
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• s.34
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• pp.54-62
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• 2007

• The Monthly Technology and Standards
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• s.21
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• pp.51-53
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• 2003

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.159-170
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• 2003

In this study, the mixed design of grout with hish strength.high permeation.high durability and environmental stability as the state of the art in material field was performed. Also, the subjects of grouting, grouting effects for ground conditions, and environmental effects were analyzed. According to these results, the fundamental data will be suggested as a design of grouting in the field application. The physical, mechanical and chemical characteristics with particle shape of the grouts were analyzed. Then, the gel-time of grouts, which is essential for workability and permeation range, were controlled. Also, the laboratory model grouting tests were performed to find the characteristics of solidification, permeation and durability with grouts. The ordinary portland, slag and microcement which have been used in the construction field were evaluated fur the environmental effects. To find the leaching of $Cr^{6+}$characteristics in cement grouts, $Cr^{6+}$ leaching tests were performed for the raw materials. Also, the results of leaching test were shorn by surrounding environment. Then, the unconfined compression strength tests were performed with the homo-gel samples, and the amount of changed $Cr^{6+}$ was measured by curing solution.

• Proceedings of the Korean Ceranic Society Conference
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• 2007.07a
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• pp.54-62
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• 2007