• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.200-202
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• 2002

This study was for comparisons of transitional element concentrations from the two different soil, serpentinite(SP) and granite area(GR), Kwangcheon and Hongseong area. Soils were collected by soil depths (10, 20 and 30cm) from the sites selected In the plant species(coniferous and deciduous species). In the soils, the SP was high in the Cr, Mn, Fe, Co, Ni and Zn concentrations, while the GR was high in the Cu, As, Sc and V. With the soil depths, the elements had high solubility, such as Cr, Co and Ni concentrations, were high in the SP, while the other elements were not clear. For the both species, the SP was high in the root and bolebark, while in the GR, not clear. Coniferous species in the same soil types, was higher than the deciduous In most elements. The more with increasing ages, the more with element accumulation in most plant parts except leaves. Comparisons between the soils and plant species, in the case of the element contents within the soils, the plant species in the same sites was similar trend. especially, clear in the SP

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.117-118
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• 2013

증기발생기 화학세정 모사 장치를 이용하여 고농도 화학세정(EPRI/SGOG) 용액인 EDTA(20%)가 인위적으로 제작한 결합 시편에 미치는 영향 평가를 수행하였다. 평가 방법은 세정 전 후 표면 산화막 성분, ECT 분석값 비교, 증기발생기 구성 재료 부식률를 이용하였다. 화학세정 전후 부식률은 A508은 $8.023{\mu}m$, Alloy 600(HTMA)은 $0.007{\mu}m$이며 갈바닉 시편의 경우 $63.193{\mu}m$로 모두 부식 허용치 이내이다. 표면 산화막 성분 및 ECT 분석값 역시 변함이 없었다. 이와 같은 결과로 화학세정 용액인 EDTA는 결함 튜브에 미치는 영향이 없는 것으로 판단된다.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.10a
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• pp.65-66
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• 2003

1. The oxidation resistance of $Y_{2}O_{3}$ containing Ni-base alloy is superior to that of the alloy without $Y_{2}O_{3}$. 2. The appearance of oxides of Ni-20Cr-20Fe-5Nb-$1Y_{2}O_{3}$ alloy is similar to that of oxides in commercial PM1000 and MA754 alloy. 3. The oxides in ODS alloy are grown mainly at particle boundaries.

• The Korean Journal of Ecology
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• v.20 no.5
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• pp.385-391
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• 1997

To investigate the degrees of toxification in the serpentine areas, serpentinites and adjacent metamorphic rocks and soils from the serpentinite, metamorphic area and transitional area(mixed soil) between serpentinite and metamorphic rocks are collected from the Hongseong-Gun, Chungnam. A plant, Geochemically, the serpentinites are high in the nickel, chromium and cobalt content whereas the metamorphic rocks show high zinc, scandium, molybdenum and iron contents. The serpentine soils are high in the nickel, chromium and cobalt contents whereas the non-serpentine soils show high zinc and iron contents. Heavy metal contents in the G. oldhamiana are high in the serpentine soil relative to the mixed soil. Ratio of the iron to nickel contents for the G. oldhamiana are low in the serpentine soil(49) relative to the mixed soil(216). Of the G. oldhamiana, most of the heavy metal contents except zinc and molybdenum are high in the root relative to the aboveground vegetation. Comparing with rocks, the G. oldhamiana is low in the all of heavy metal contents relative to the serpentinite. Uptake of zinc by the G. oldhamiana is high in the serpentinites and metamorphic rocks whereas uptake of scandium and iron by the G. oldhamiana is very high in the serpentinite area.

• Journal of Welding and Joining
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• v.20 no.2
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• pp.82-89
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• 2002

In order to clarify hot cracking phenomena occurred in Inconel 690 welds and it's prevention, in this study, the cracking behavior and the influence of welding variables on cracking in Inconel 690 overlay welds on Mn-Ni-Cr-Mo steel(SA 508 cl.3) for pressure vessel were investigated by using mock-up test. The main results are as follows: The cracks in Inconel 690 overlay welds were mainly generated near the start and the end part of welding beads adjacent to STS 309L welded outside of Inconel 690 welds. Most of the cracks showed typical solidification crack, and also it was assumed that there was possibility of liquation cracking in HAZ. The existence of Nb constituents or concentration of Nb was recognized on the fracture facets of the solidification cracks in the welds by SMAW. Therefore Nb was considered to be the main factor of the solidification cracking. As the weld heat input was more increased and the weld bead length was longer, the extent of cracking was more increased. Moreover the extent of cracking was considerably decreased by changing of welding sequence to the start and the end part of welds. Hot cracking in welds by GTAW was considerably decreased as compared with that of SMAW. And cracks were well generated in the Inconel 690 overlay welds adjacent to 575 309L welds. This means that the hot cracking susceptibility of Inconel 690 welds was largely varied by chemical components and/or compositions of filter metals, base metals and neighboring welds.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.289-295
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• 2010

Monitoring of the heavy metals at paddy rice agriculture is very important for environmental agriculture. A study was carried out of heavy metal concentrations in 260 paddy soil samples every four years from 1999 to 2007 in Gyeongnam Province. Heavy metals such as Cd, Cr, Cu, Ni, Pb, Zn, and As in paddy soils were analyzed. Average concentrations of heavy metal were Cd 0.426 (ranged 0.003-1.379) mg $kg^{-1}$ for Cd, 1.189 (0.003-3.264) mg $kg^{-1}$, for Cr, 9.68 (0.05-22.38) mg $kg^{-1}$ for Cu, 2.64 (0.01-7.36) mg $kg^{-1}$ for Ni, 23.7 (0.7-54.1) mg $kg^{-1}$ for Pb, 20.8 (0.7-131.2) mg $kg^{-1}$ for Zn, and 1.054 (0.001-2.110) mg $kg^{-1}$ for As, respectively. Long-term changes of heavy metals were showed that Cd, Ni, and Zn were significantly increased whereas Cr, Cu, and As were significantly decreased. Principle component analysis (PCA) of heavy metals in paddy soils was obtained with eigenvalues > 1 summing 34.3% of variance for PC1, 17.5% of variance for PC2, and 51.8% of the total variance in soil heavy metals.

• Journal of Environmental Science International
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• v.15 no.6
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• pp.503-511
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• 2006

Airborne particles collected from a heavily industrialized site were analyzed by chemical speciation of seven trace metals: Pb, Cd, Cr, Cu, Ni, Zn, and As. The average concentrations were as follows: $Zn,\;502.0{\pm}230.7;\;Pb,\;176.5{\pm}310.9;\;Cu,\;111.9{\pm}82.7;\;As,\;38.0{\pm}31.0;\;Cr,\;21.5{\pm}24.4;\;Cd,\;20.8{\pm}17.4;\;and\;Ni,\;11.4{\pm}8.4\;ng/m^3$. The median enrichment factor (EF) values of Cd (7,280), As (1,030), Cu (215), Zn (214), and Pb (143), with respect to iron, were much larger than 100. We observed that Cd was found in the soluble and exchange- able form (56.9%), and that Pb and Cr were found in carbonates, oxides and the reducible form (69.8% and 61.1%, respectively). These two forms, which are the most easily absorbed into human body tissue, predominated in most of the trace metals investigated in this study.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.35-40
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• 2002

In the present study, we examined the influence of prestrain on creep strength of Class M alloy(STS310S) and Class A(STS310J1TB) alloys containing precipitates. Prestrain was given by prior creep at a higher stress than the following creep stresses. Creep behaviour before and after stress change and creep rate of pre-strianed specimens were compared with that of virgin specimens. Pre-straining produced the strain region where the strain rate was lower than that of a virgin specimen both for STS310J1TB and STS310S steels. The reason for this phenomenon was ascribable to the viscous motion of dislocations, the interaction between dislocations and precipitates in a STS310J1TB steel, and the interaction of dislocations with sub-boundaries in a STS310S steel which has the higher dislocation density and smaller subgrain size resulted from pre-straining at higher stress.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.7
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• pp.681-686
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• 2009

Direct laser metal forming technology was applied to restore the damaged mold surface. In order to estimate melting characteristics of the $20{\mu}m$ Fe-Cr-Ni powder, single layer experiments were performed at various levels of heat input. The process window of the $20{\mu}m$ Fe-Cr-Ni powder provided feasible process parameters for the smooth regular surface. The cross hatching scanning strategy on the multiple layer experiment was performed to reduce the thickness non-uniformity of edge portions compared with the one direction scanning. To estimate the coherence between the melted powder and the basematal, the tendency of hardness distribution has been observed. The hardness of the melted and the remelted zone was distributed from 400HV to 600HV. It is over 2 times compared of the hardness of the basemetal. Experimental results show that the mold restoring process using direct laser metal forming can be successfully applied in the mold repair industry.

• Corrosion Science and Technology
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• v.20 no.6
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• pp.347-360
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• 2021

Currently, the demand for eco-friendly energy sources is high, which has prompted research on polymer electrolyte membrane fuel cells. Both aluminum alloys and nickel alloys, which are commonly considered as materials of bipolar plates in fuel cells, oxide layers formed on the metal surface have excellent corrosion resistance. In this research, the electrochemical characteristics of 6061-T6 aluminum alloy and Inconel 600 were investigated with chloride concentrations in an acid environment that simulated the cathode condition of the PEMFC. After potentiodynamic polarization experiments, Tafel analysis and surface analysis were performed. Inconel 600 presented remarkably good corrosion resistance under all test conditions. The corrosion current density of 6061-T6 aluminum alloy was significantly higher than that of Inconel 600 under all test conditions. Also, 6061-T6 aluminum alloy and Inconel 600 presented uniform corrosion and intergranular corrosion, respectively. The Ni, Cr, and Fe, which are the main chemical compositions of Inconel 600, are higher than Al in the electromotive force series. And a double oxide film of NiO-Cr₂O₃, which is more stable than Al₂O₃, is formed. Thus, the corrosion resistance of Inconel 600 is better.