• 대한환경공학회지
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• 제32권1호
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• pp.69-78
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• 2010

일반주택의 먼지오염실태를 연구하기 위하여 2009년 1월부터 2월까지 대구지역내의 도시지역(24곳) 및 농촌지역(24곳)의 일반주택 48가구를 대상으로 진공청소기에 포집된 먼지를 수거한 뒤 100 ${\mu}m$ 이하로 체거름하고 산추출한 후에 발암물질로 알려진 Cd과 Ni을 포함한 모두 14개 원소(Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V, Zn)를 ICP로 분석하였다. 농축계수를 이용한 발생원을 평가한 결과, Ca, Fe, K, Mg, Mn, Na, V 성분은 암석풍화, 토양의 재비산 등과 관련된 자연적인 발생원의 영향을 받았고, Cd, Cr, Cu, Ni, Pb, Zn 성분은 연료의 연소, 폐기물소각 등과 관련된 인위적인 발생원의 영향을 받고 있는 것으로 추정되었다. 미량원소성분의 농도는 자연적인 발생원성분에서 유래되는 성분이 높았고, 인위적인 발생원에서 유래되는 성분이 낮았다. 인위적인 발생원의 기여도는 도시지역(2.5%)의 먼지가 농촌지역(2.0%)의 먼지에 비해 높았다. 오염지수를 이용한 중금속성분의 오염도를 평가한 결과, 도시지역이 농촌지역에 비해 1.8배정도 높게 오염된 것으로 추정되었다. 지역별 미량원소성분간의 상관성을 분석한 결과, 농촌지역과 도시지역이 공통적으로 자연적-자연적 발생원 성분간(Al-Mg, Al-Mn, Fe-Mn), 자연적-인위적 성분간(Al-V, Fe-Cr, V-Mn)이 유의하게 양호하였다. 그리고 농촌지역이 도시지역보다 유의한 상관성이 많았다. 또한 유해 중금속성분과 영향인자간의 상관성을 분석한 결과, 난방연료로 기름을 사용하는곳이 가스나 전기를 사용하는 곳보다, 어린이가 있는 곳이 없는 곳보다, 주택과 대도로 사이가 10 m 미만인 곳이 이상인 곳보다, 주택연수가 10년 이상인 곳이 미만인 곳보다 상대적으로 중금속을 많이 함유하고 있었다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.612-619
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• 2002

The dynamic behavior of Al-Mg alloys plasma was very unstable and this instability was closely related to the unstable motion of keyhole during laser irradiation. The keyhole fluctuated both in size and shape and its fluctuation period was about 440 ${\mu}{\textrm}{m}$. This instability has been estimated to be caused by the evaporation phenomena of metals with different boiling point and latent heats of vaporization. Therefore, the authors have conducted the spectroscopic diagnostics of plasma induced in the pulsed YAG laser welding of Al-Mg alloys in air and argon atmospheres. In the air environment, the identified spectra were atomic lines of Al, Mg, Cr, Mn, Cu, Fe and Zn, and singly ionized Mg line, as well as strong molecular spectrum of AlO, MgO and AIH. It was confirmed that the resonant lines of Al and Mg were strongly self-absorbed, in particular in the vicinity of pool surface. The self-absorption of atomic Mg line was more eminent in alloys containing higher Mg. These facts showed that the laser-induced plasma was relatively a low temperature and high density metallic vapor. The intensities of molecular spectra of AlO and MgO were different each other depending on the power density of laser beam. Under the low power density irradiation condition, the MgO band spectra were predominant in intensity, while the AlO spectra became much stronger in higher power density. In argon atmosphere the band spectra of MgO and AlO completely vanished, but AlH molecular spectra was detected clearly. The hydrogen source was presumably the hydrogen solved in the base Metal, absorbed water on the surface oxide layer or H$_2$ and $H_2O$ in the shielding gas. The temporal change in spectral line intensities was quite similar to the fluctuation of keyhole. The time average plasma temperature at 1 mm high above the surface of A5083 alloy was determined by the Boltzmann plot method of atomic Cr lines of different excitation energy. The obtained electron temperature was 3, 280$\pm$150 K which was about 500 K higher than the boiling point of pure aluminum. The electron number density was determined by measuring the relative intensities of the spectra1lines of atomic and singly ionized Magnesium, and the obtained value was 1.85 x 1019 1/㎥.

• 한국주조공학회지
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• 제13권3호
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• pp.285-294
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• 1993

Aluminum alloy 2024 matrix composites reinforced with $Al_2O_3$ particles, were prepared by rheo-compocasting, a process which consists of the incoporation distribution of reinforcement by stirring within a semi-solid alloy. The microstructures and characteristics of the interfaces have been studied using optical microscope and scanning electon microscope in 2024 aluminum alloy composites reinforced with $Al_2O_3$ particles. The main results are as follows: (1) $Al_2O_3$ particles were well distributed in composites by using rheo-compocasting. (2) As the addition of $Al_2O_3$ particle increases, the average dendrite numbers and the hardness were increased. (3) Interaction between $Al_2O_3$ particles and alloy 2024 resulted in the formation of Mg and Cu element rich region around the $Al_2O_3$ particles.

• 환경위생공학
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• 제16권2호
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• pp.47-55
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• 2001

We investigated to find the optimum operation condition of electrolysis which have an influence on removal efficiency of heavy metals. When we experimented the testing wastewaters containing each 250mg/L of Cu and Ni ions, we got the variables like as pH, amount of electrolyte(NaCl), different species of electrode, electrode gap, electric strength, the number of electrodes, after fastening positive electrode plate with Al, Fe, Ti and negative electrode plate with Stainless Steel plate.

• 한국자원공학회지
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• 제55권6호
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• pp.588-595
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• 2018

이 연구에서는 국내에 분포하는 광산폐기물(광물찌꺼기, 폐(광)석) 적치장의 침출수 유출 현황을 조사하고 중금속 오염도를 평가하였다. 현장답사 시 채취한 23개소의 적치장 침출수 미량원소 분석결과 원소별 최대함량(mg/L)은 Al 53.98, As 16.19, Cd 1.15 Cu 37.30, Fe 28.64, Mn 39.00, Ni 0.097, Pb 0.750으로 검출되었다. 모니터링 대상 적치장 6개소의 침출수를 3개월간 분석한 결과, 주요 개발광종에 따라 2개소의 금-은광산에서는 As, Cd, Cu, Fe, Mn, Zn 및 Al, 2개소의 연-아연광산에서는 Cd, Mn, Zn 및 Al, 2개소의 기타광종(중석, 철) 개발광산에서는 As, Fe, Mn이 지속적으로 수질환경기준을 초과하는 높은 함량이 유출되고 있음을 확인하였다. 그러므로 이들 6개 광산폐기물 적치장에서 배출되는 침출수에 대한 지속적인 모니터링이 필요하다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.176-179
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• 2005

Spray casting of hypereutectic Al-Si based alloy has been reported to provide distinct advantages over ingot metallurgy (IM) or rapid solidification/powder metallurgy (RS/PM) process in terms of microstructure refinement. Hypereutectic Al-Si based alloys have been regarded attractive for automotive and aerospace application, due to high specific strength, good wear resistance, low coefficient of thermal expansion, high thermal stability, and good creep resistance. In this study, hypereutectic Al-25Si-2.0Cu-1.0Mg alloy was prepared by OSPREY spray casting process. High temperature deformation behavior of the hypereutectic Al-Si based alloy has been investigated by applying the internal variable theory proposed by Chang et al. The change of strain rate sensitivity and Creep transition were analyzed by using the load relaxation test and constant creep test.

• 한국세라믹학회지
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• 제28권3호
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• pp.243-251
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• 1991

High-Tc YBa2Cu3O7-x superconducting thin films have been prepared by single-target off-axis RF magnetron sputtering. Optimal ratio of Y : Ba : Cu of the single-target was determined as 1 : 1.65 : 3.35 in order to obtain the stoichiometric films. Tc, crystalline phase, and microstructures of the surface and cross-section of the ex-situ YBa2Cu3O7-x thin films on MgO(100) had a Tc, zero of 80K, and the films on LaAlO3/Si had a Tc, on-set of 90 K and a Tc, zero of 70 K.

• 한국환경보건학회지
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• 제30권5호
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• pp.455-468
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• 2004

The purpose of this paper is to understand the time series and origin of a chemical component and to compare the difference during yellow sand episodes for analysis $PM_{10}$ chemical components in the region of west in Korean Peninsula, 1999-2001. An annual mean concentration of $PM_{10}$ is $29.1\;{\mu}g/m^3$. A monthly mean and standard deviation of $PM_{10}$ concentration are very high in spring but there is no remarkably seasonal variation. Also, water soluble ionic component of $PM_{10}$ be influenced by double more total anion than total cation, be included $NO_{3}^-\;and\;SO_{4}^{2-}$ for the source of acidity and $NH_{4}^+$ to neutralize. Tracer metals of $PM_{10}$ slowly increases caused by emitted for soil and ocean (Fe, Al, Ca, Mg, Na) and Zn, Pb, Cu, Mn for anthropogenic source. According to method of enrichment factor (E.F) and statistics, assuming that the origin of metal component in $PM_{10}$ most of element in the Earth's crust e.g. Mg, Ca, Fe originates soil and Cu, Zn, Cd, Pb derives from anthropogenic sources. The ionic component for $Na^{+}\;Cl^-,\;Mg^{2+}\;and\;Ca^{2+}$ and Mg, Al, Ca, Fe originated by soil component largely increase during yellow sand period and then tracer metal component as Pb, Cd, Zn decrease. According to factor analysis, the first group is ionic component ($Na^+,\;Mg^{2+},\;Ca^{2+}$) and metal component (Na, Fe, Mn and Ni) be influenced by soil. The second group, Mg, Cr also be influenced by soil particle.

• 한국주조공학회지
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• 제20권1호
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• pp.38-45
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• 2000

The remelting for recycling or thin aluminum scrap, such as aluminum chip generally involves melting of these pieces submerged in molten salt flux. In this study, the effects of salt flux compositions and alloying elements on the aluminum dropletscoalescence and oxide film removal were studied in 99.8%Al, Al-1.01%Cu, Al-1.03%Si, and Al-1.38%Mg alloys as a function of holding time at $740^{\circ}C$ Salt fluxes based on NaCl-KCl(1:1) with addition of 5wt.% fluorides(NaF, $Na_3AlF_6$, $CaF_2$) or 5 wt.% chloride($MgCl_2$, $AlCl_3$) were used. The experimental results show that NaCl-KCl(1:1) with addition of 5 wt.% fluorides exhibits better coalescence ability than that with chlorides. The oxide film is not removed by NaCl-KCl(1:1) with addition of 5 wt.%chlorides, while it is removed by NaCl-KCl(1:1) with addition of 5 wt.% fluorides. The aluminum droplets coalescence and oxide film removal by salt fluxes are related to interfacial tension tension between metal and salt flux.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 춘계학술대회 논문집
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• pp.155-156
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• 2015

최근 자동차 및 항공기의 경량화 관련하여 알루미늄 합금의 필요성이 높아지고 있으나, 자동차재료에 쓰이는 알리미늄 합금의 경우 높은 이온화 경향 때문에 Fe, Cu, Pb 등과 접촉하면 쉽게 부식되는 단점이 있다. 본 연구에서는 기존의 Magsimal-59 샘플과 본 연구에서 개발한 고용질, 저용질 Duplex 알루미늄 합금과의 내식성을 분극 및 갈바닉을 통해 확인하고, 균질화처리를 통해 내식성을 개선한다.