• Analytical Science and Technology
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• v.14 no.3
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• pp.253-258
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• 2001

This is a research on hazardous characteristics and potentials of bottom ash from 9 municipal solid waste combustors(200 tons/day) of Korea by the test methods of leaching and content. The leaching method was performed by Waste Test Method of Korea. In case of the content method, mercury was determined by thermal decomposition amalgamation atomic absorption spectrometer, other 9 elemets including Pb, which were pretreated by U.S.EPA SW-846 3050B method, were determined by flame atomic absorption spectrometer(FAAS) or inductively coupled plasma atomic emission spectrometer(ICP-AES). Results of leaching test showed that Pb and Cu was main pollutants. It was interested that the distribution rate of metals' contents of each combustors was similar and the rank of concentration was Fe>Zn>Cu>Mn>Pb>Cr>As>Cd>Hg.

• Journal of Powder Materials
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• v.24 no.4
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• pp.292-297
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• 2017

A metallic oxide layer of a heat-resistant element contributes to the high-temperature oxidation resistance by delaying the oxidation and has a positive effect on the increase in electrical resistivity. In this study, green compacts of Fecralloy powder mixed with amorphous and crystalline silica are oxidized at $950^{\circ}C$ for up to 210 h in order to evaluate the effect of metal oxide on the oxidation and electrical resistivity. The weight change ratio increases as per a parabolic law, and the increase is larger than that observed for Fecralloy owing to the formation of Fe-Si, Fe-Cr composite oxide, and $Al_2O_3$ upon the addition of Si oxide. Si oxides promote the formation of $Al_2O_3$ and Cr oxide at the grain boundary, and obstruct neck formation and the growth of Fecralloy particles to ensure stable electrical resistivity.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.111-111
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• 2018

ASTM A387-Gr.91 강은 우수한 고온 강도, 크리이프 저항성 그리고 내산화성 등으로 인해 화력 및 바이오매스 발전 시설과 같은 고온 설비의 구조재료로 널리 사용되고 있다. 고온 환경에서 높은 강도는 탄화물과 탄질화물에 의한 석출강화가 주 요인으로 작용한다. 열처리 과정에서 Mo, Cr, Mn, 그리고 Fe는 구-오스테나이트 및 마르텐사이트 라스 입계에 $M_{23}C_6$ 탄화물로 석출되며, V, Nb, 및 N은 조직 내부에 미세한 MX 탄질화물로 석출된다. 따라서 합금의 고온 강도는 조직 내 석출물의 개수밀도와 크기에 크게 의존한다. 그러나 적용 환경의 특성 상 고온 노출에 따른 2차상 석출 및 조대화의 조직열화 현상이 발생하며, 이는 재료의 강도를 저하시킨다. 본 연구에서는 ASTM A387-Gr.91 강의 미세조직 열화에 따른 강도저하 및 파괴 양상을 고찰하는데 그 목적을 두었다. 본 연구에서 사용된 ASTM A387-Gr.91 강의 화학성분(wt, %)은 0.1 C, 0.38 Si, 0.46 Mn, 0.25 Ni, 8.38 Cr, 0.93 Mo, 0.18 V, 0.09 Nb, 그리고 나머지는 Fe 이다. 조직열화 및 기계적 강도저하 특성을 평가하기 위한 등온열화는 $650^{\circ}C$의 대기 환경에서 최대 1000시간동안 실시하였다. 열화된 시험편의 미세조직 및 탄화물에 대한 분석은 SEM과 EDS를 이용하여 실시하였다. 그리고 기계적 강도 평가는 인장실험과 비커스 경도시험을 통해 실시하였다. 또한 열화 시간에 따른 파단양상의 변화를 관찰하기 위해 인장시험편의 파단면을 SEM과 EDS를 이용하여 분석하였다. 그 결과, 열화에 따른 마르텐사이트 라스의 소실, 탄화물의 조대화, 그리고 2차상 석출의 조직 열화현상이 나타났다. 또한 기계적 강도는 조직 열화에 따라 저하되는 경향을 나타냈다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.2
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• pp.81-87
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• 2001

Populus euramericana and Betula platyphylla var. japonica have been identified as possible species for use for phytoremediation of landfills. To identify the capacity of waste leachate absorption in Populus euramericana and Betula platyphylla var, japonica, four different treatments were applied to these seedlings: leachate solution (100% leachate), 50% dilution (50% leachate: 50% water, v/v) and 25% dilution (25% leachate: 75% water, v/v) were applied to these two species. After the experiment, concentrations of heavy metals in tree biomass were analyzed by Inductively Coupled Plasma emission spectrometer (ICP). These two species can take up the hazardous parts of the leachate such as heavy metals. Especially, these species showed good absorption capacity of Al, Cr, and Fe elements. The result of this study suggested that these two species can take up the toxic materials through their roots and transport them to stems or leaves.

• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.2042-2049
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• 2019

Ten gizzard and three flesh samples of the broiler were collected from different locations in Tehsil Gujar Khan District Rawalpindi, Pakistan. The samples were dried, crushed and ground. Pellets were prepared by pressing the powder of the samples and that of the Bovine liver 1577c reference material obtained from NIST, USA. Proton induced X-ray emission (PIXE) installed at National Center for Physics, Islamabad, Pakistan has been used as a reliable and improved technique to determine concentration of various major/trace and toxic elements e.g. S, Cl, K, Ca, Cl, Fe, Cu, Mn, Co, Zn, Ti, Cd, Ga, Cr, V and Ni, in the Gizzard and Flesh samples of the broiler. The concentrations of all the detected elements in the samples are statistically significant. The certified and measured values of the elements in the reference material were in agreement with each other within a deviation of 7%. S, Cl, K and Ca are within tolerable limits and are good for human consumption. Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn were more than the acceptable limits of World Health Organization, WHO whereas Ga, As, Sn, Sb and Pb are not detected in most of the samples.

• Clean Technology
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• v.17 no.4
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• pp.353-362
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• 2011

In our nature, the utilization of rainwater is essential for healthy water recirculation. This is one of the solutions of the increment of impermeability surface according to the development of new cities; this study of the improvement of rainwater quality has been carried on through the improvement of collecting and restoring system of rainwater. The southwestern region of Daejeon City, the rainwater coefficient of run off was 0.40 and this number had computed to 0.59 after the development. After filtration of rainwater, the heavy metal (Cu, As, Cr, Fe, Mn) contents level were lower than underground water. Moreover, collected rainwater showed better quality than underground water in following criteria; hardness, permanganate consumption quality, chloride, evaporation residue, sulfates and nitrate nitrogen. This water quality met the gray water quality standards. The rainwater quality was still suitable to use as bathroom flushing and gardening after 100 days of storage. This study proved that modification (installation of cover with gutter to existing rainwater collection system, proper filtering, and installation of underground storage tank) of collection system could improve quality of water and maintain this approximately 100 days.

• Korean Journal of Materials Research
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• v.9 no.10
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• pp.985-991
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• 1999

Corrosion behaviors of Incoloy 800H, KSA(Kaeri Superalloy)-6, Inconel 600 and Hastelloy C-276 in molten salts were investigated in the temperature range of 650 ~ $850^{\circ}C$. Due to $\textrm{Li}_{2}\textrm{O}$-induced basic fluxing mechanism, the corrosion rates of the alloys in mixed molten salt of LiC1-$\textrm{Li}_{2}\textrm{O}$ were significantly higher than those in molten salt of LiCl. In the mixed molten salt, Fe-base alloys showed higher corrosion resistance than the Ni-base alloys. and Hastelloy C-276 with high Mo and W contents exhibited the highest corrosion rate among the examined alloys. The single layer of $\textrm{LiCrO}_{2}$ was formed in molten salt of LiCl and two phase structure of a scale consisted of oxides and Ni was formed in the mixed molten salt.

• Journal of Welding and Joining
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• v.29 no.4
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• pp.85-92
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• 2011

Microstructures and tensile properties in arc brazed joints of ferritic stainless steel, 429EM using Cu-8.6%Al insert metal was investigated as function of brazing current. The brazing speed was fixed at 800mm/min and brazing current varied in the range of 80A to 120A. The initial phase of filler metal was Cu single phase. However, the insert metal structures of brazed joints was composed of Cu matrix and intermetallic compound such as ${\gamma}_1(Al_4Cu_9)$, and flower-shape Fe-Cr. The fraction of ${\gamma}_1(Al_4Cu_9)$ phase was similar with 80A and 100A brazing currents while that of brazed with 120A was decreased. On the other hand, the fraction of Fe-Cr phase increased with increasing of the brazing current. A reaction layer at the base metal/insert metal interface was observed and this reaction layer was thickened with increasing of the brazing current. In the brazed joints with the current lower than 100A, crack was grew up along the interface which was perpendicular to the tensile stress, and then, passed through the insert metal in the final stage of fracture. As the brazing current increased to 120A, fracture occurred at the base metal.

• Journal of the Korean Vacuum Society
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• v.5 no.4
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• pp.377-386
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• 1996

Austenitic stainless steel type 304L has been nitrided under the low pressure of high nitrogen environment for 5 hours by the square-wave-pulse-d.c. plasma as a function of temperature 400~$600^{\circ}C$ and of pulsation. At the temperature range lower than $500^{\circ}C$ and at the relatively high ratio of pulse duration to pulse period, nonstoichiometric stainless steel nitride has been developed in the form of a thin layer which has many cracks. At the temperature range higher than $500^{\circ}C$, with the increasing temperature or with the increasing ratio of the pulse duration to pulse period up to 50s/100s, the nitrided layer was composed mainly of CrN and Fe4N phases and became thick, uniform, columnar and nearly crack-free. The nitrided layer at $500^{\circ}C$ was mixed with the low-temperature layer and the high temperature layer and was very brittle.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.83-84
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• 2014

This study evaluated the effectiveness of biostimulating agent in contaminated coastal sediment. The study was conducted via column tests in coastal sea wherein two separate columns were employed for two different polymers used and another column for a blank. The biostimulating agent was made by mixing sea sediment with biostimulants viz acetate, nitrate, sulfate. The biostimulating agent was then rolled into balls, dried and coated with either Cellulose Acetate (CA) or Polysulfone (PS) to control the release of the biostimulants. The pH was around 7.6~8 for 4 months while COD, TP and TN were significantly lower in the column containing biostimulating agents. Heavy metal(Fe, Zn, Cd, Cr, Pb, Cu) was converted to stable forms and PS coated biostimulating agent had a high efficiency of heavy metals distribution.