• 한국대기환경학회지
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• 제13권4호
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• pp.307-317
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• 1997

Samples of fine particle $(d_P<2.5 \mum)$ were taken in Chongju area using a dichotomous sampler. The data set was collected on fifty-eight different days with 24 hour sampling period from October 27, 1995 through August 25, 1996. The samples were analyzed using a proton induced x-ray emission (PIXE) for Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, M, Fe, Ni, Cu, Zn, Br and Pb. Values of Fe, Ca, Si, Cu, K and Cl exhibit marked seasonal variations. Mean concentrations for this study had the following order S > Cl > Si > K > Al > Fe on fine particle. Concentrations of Ca, Si and Fe were higher during the spring season compared with any other season. These phenomena may be attributable to soil dust. Cl and K were higher in the winter, which may be explained by combustion of fossil fuel. Higher values for Cu and Zn in the Winter may be due to the combustion and incineration.

• Membrane and Water Treatment
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• 제11권4호
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• pp.283-294
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• 2020

This work aims at studying the feasibility of continuous removal of mixed heavy metal ions from simulated zinc plating wastewaters by coupling a microbial fuel cell and a microbial electrolysis cell in batch and continuous modes. The discharging voltage of MFC increased initially from 0.4621 ± 0.0005 V to 0.4864 ± 0.0006 V as the initial concentration of Cr⁶⁺ increased from 10 ppm to 60 ppm. Almost complete removal of Cr⁶⁺ and low removal of Cu²⁺ occurred in MFC of the MFC-MEC-coupled system after 8 hours under the batch mode; removal efficiencies (REs) of Cr⁶⁺ and Cu²⁺ were 99.76% and 30.49%. After the same reaction time, REs of nickel and zinc ions were 55.15% and 76.21% in its MEC. Cu²⁺, Ni²⁺, and Zn²⁺ removal efficiencies of 54.98%, 30.63%, 55.04%, and 75.35% were achieved in the effluent within optimum HRT of 2 hours under the continuous mode. The incomplete removal of Cu²⁺, Ni²⁺ and Zn²⁺ ions in the effluent was due to the fact that the Cr⁶⁺ was almost completely consumed at the end of MFC reaction. After HRT of 12 hours, at the different sampling locations, Cr⁶⁺ and Cu²⁺ removal efficiencies in the cathodic chamber of MFC were 89.95% and 34.69%, respectively. 94.58%, 33.95%, 56.57%, and 75.76% were achieved for Cr⁶⁺, Cu²⁺, Ni²⁺ and Zn²⁺ in the cathodic chamber of MEC. It can be concluded that those metal ions can be removed completely by repeatedly passing high concentration of Cr⁶⁺ through the cathode chamber of MFC of the MFC-MEC-coupled system.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.665-665
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• 2013

박막형 태양전지에서 광흡수층으로 널리 쓰이는 metal chalcogenide 화합물 중, CuInS2(CIS)은 전기적, 광학적 특성이 우수하여 널리 연구되고 있다. CIS계 태양전지 최근 동시 증발법을 이용하여 20.3%의 고효율을 기록한 바 있으나 기존 진공, 고온 기반 공정 기술은 초기 투자 비용이 높고, 고가의 희귀원소인 In 등의 원료 활용도가 떨어져 원가 절감에 있어 한계가 있다. 이에 따라 제조 비용 절감과 원료 사용 효율을 향상시키기 위해 비진공 방식을 이용한 광흡수 층 증착 공정에 관한 연구가 활발히 진행되고 있다. 본 연구에서는 상온, 상압, 저온에서 합성이 가능한 CIS계 광흡수층을 전자 전달 및 빛 포집에 유리한 ZnO 나노구조와 응용함으로써 superstrate 구조의 박막형 태양전지를 구현하고 그 특성을 평가하였다. CIS 박막 태양전지에서 투명창층으로 쓰이는 ZnO 박막을 수열합성법으로 합성된 ZnO 나노로드 어레이로 대체하여 빛 산란 효과를 줄이고, 전하 수집 및 이동 효과를 극대화하였다. 또한 CIS 광흡수층은amine계 용매와 금속염 및 thiourea를 조합하여 저온에서 코팅 후 건조시켜 박막을 제조하였다. 각 요소 박막들의 물성을SEM, XRD, UV-transmittance 분석을 통해 살펴보았으며, 소면적 태양전지 제작을 통해 박막 구조 대비 30배 이상의 광변환효율(최고효율 3.30%)을 기록하였다.

• 환경생물
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• 제38권1호
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• pp.82-92
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• 2020

축산 폐수는 고농도의 영양염류와 중금속을 함유하고 있어, 배출될 때 수질을 악화시킨다. 기존 처리 기술과 비교하여 bioremediation은 축산 폐수 처리에 유능하다. 특히, 미세조류는 오염물질 제거에 잠재력을 가지고 있다. 본 연구에서는 Ankistrodesmus bibraianus를 이용하여 축산 폐수 내 영양염류(질소(N), 인(P))와 중금속(구리(Cu), 아연(Zn))의 제거 가능성을 평가하고, A. bibraianus의 최적 배양조건을 확립하였다. 연구결과, 최적 배양조건은 28℃, pH 7, 광주기는 14:10 h로 설정되었다. N과 P의 단일 처리구(500, 1,000, 5,000, 10,000mg L^-1)에서 제거효율은 각각 22.9~80.6%와 11.9~50.0%였다. 또한, N과 P의 복합 처리구에서 제거효율은 각각 16.4~58.3%와 7.80~49.8%였다. Cu와 Zn의 단일 처리구(10, 30, 50mg L^-1)에서 제거효율은 각각 15.5~81.5%와 6.28~34.3%였다. 유사하게, Cu와 Zn의 복합 처리구에서 제거효율은 각각 16.7~74.5%와 5.58~27.5%였다. 또한 영양염류(N 및 P)와 중금속(Cu 및 Zn)의 성장 및 제거효율을 축산 폐수에 적용할 수 있음을 나타냈다. 본 연구의 결과에 따르면 A. bibraianus는 축산 폐수 내 영양염류와 중금속 제거에 이용할 수 있을 것으로 사료된다.

• 한국재료학회지
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• 제11권6호
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• pp.448-452
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• 2001

ZnS:Cu,Cl 형광체를 이용하여 ITO/glaas 기판위에 스크린인쇄법으로 적층형과 혼합형 구조로된 2종류의 교류전계 발광소자를 제작한 후 인가전압과 주파수에 따른 광학적, 전기적 특성을 조사, 비교하였다. 적층헝의 경우 발광휘도는 400Hz, 200V 구동전압에서 약 55 cd/$\m^2$를 나타내었다. 인가전압의 주파수를 400Hz에서 30Hz로 증가시킬 경우 휘도는 420 cd/$\m^2$로 크게 향상되었다. 혼합형의 경우 400Hz의 주파수에서 문턱전압은 45V이었고, 200V, 30KHz 주파수의 동작조건에서 최대휘도는 670 cd/$\m^2$ 이었다. 휘도-전압 특성 측정결과 적층형구조 보다 혼합형 소자구조에서 발광강도가 약 1.5배 증가하였다. 주파수에 따른 주발광 파장의 변화는 양쪽시료 모두 유사하게 나타났다. 1KHz이하의 저주파에서는 652 nm의 청녹색 발광과장을 나타내었으며 5KHz이상에서는 452 nm과장의 청색발광을 나타내었다.

• 비파괴검사학회지
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• 제28권6호
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• pp.477-482
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• 2008

The influence of dislocation substructure of metallic materials on ultrasonic velocity has been experimentally investigated. The test materials of pure Cu, brass (Cu-35Zn), 2.25Cr-1Mo steel, and AISI 316 with different stacking fault energy (SFE) are plastically deformed in order to generate dislocation substructures. The longitudinal wave velocit $(C_L)$ decreases as a function of tensile strain in each material. The $C_L$ of Cu-35Zn and AISI 316 decreases monotonously with tensile strain, but $C_L$ of Cu and 2.25Cr-1Mo steel shows plateau phenomena due to the stable dislocation substructure. The variation of ultrasonic velocity with the extent of dislocation damping and dislocation substructures is discussed.

• Environmental Analysis Health and Toxicology
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• 제18권3호
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• pp.175-182
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• 2003

Bisphenol A shares similarities in structure, metabolism and action with DES, a known human teratogen and carcinogen. Bisphenol A, a monomer of polycarbonate and epoxy resins, has been detected in canned food and human saliva. The purpose of the this study was to evaluate the cytotoxicity, cell proliferation of bisphenol A In the presence of a rat liver S9 mix, contaning cytochrome P450 enzymes, and Cu (II). In the present study, Bisphenol A in combination with Cu (II) exhibited a enhancement in cytotoxicity which were inhibited by free radical scavengers. The content of malondialdehyde, an end product of lipid peroxidation, was also found to increase with concentration of bisphenol A. Also, we examined the change of CuZn-SOD, Mn-SOD, catalase and GPx activities in the MCF-7 cells exposed to bisphenol A. The activities of CuZn-SOD, CPx, catalase were found to decrease with bisphenol A concentration. Meanwhile, the activity of Mn-SOD was unchanged. This indicated that elevated oxidative stress caused by imbalance between the production and removal of free radicals occurred in cells.

• 한국재료학회지
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• 제30권3호
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• pp.131-135
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• 2020

Silver nanowire (AgNW) networks have been adopted as a front electrode in Cu(In,Ga)Se2 (CIGS) thin film solar cells due to their low cost and compatibility with the solution process. When an AgNW network is applied to a CIGS thin film solar cell, reflection loss can increase because the CdS layer, with a relatively high refractive index (n ~ 2.5 at 550 nm), is exposed to air. To resolve the issue, we apply solution-processed ZnO nanorods to the AgNW network as an anti-reflective coating. To obtain high performance of the optical and electrical properties of the ZnO nanorod and AgNW network composite, we optimize the process parameters - the spin coating of AgNWs and the concentration of zinc nitrate and hexamethylene tetramine (HMT - to fabricate ZnO nanorods. We verify that 10 mM of zinc nitrate and HMT show the lowest reflectance and 10% cell efficiency increase when applied to CIGS thin film solar cells.

• 한국분말재료학회지
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• 제19권3호
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• pp.177-181
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• 2012

Copper composite materials have attracted wide attention for energy applications. Especially $CuInS_2$ has a desirable direct band gap of 1.5 eV, which is well matched with the solar spectrum. $CuInS_2$ nanoparticles could make it possible to develop color-tunable $CuInS_2$ nanoparticle emitter in the near-infrared region (NIR) for energy application and bio imaging sensors. In this paper, $CuInS_2$ nanoparticles were successfully synthesized by thermo-decomposition methods. Surface modification of $CuInS_2$ nanoparticles were carried out with various semiconductor materials (CdS, ZnS) for enhanced optical properties. Surface modification and silica coating of hydrophobic nanoparticles could be dispersed in polar solvent for potential applications. Their optical properties were characterized by UV-vis spectroscopy and photoluminescence spectroscopy (PL). The structures of silica coated $CuInS_2$ were observed by transmission electron microscopy (TEM).

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권1호
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• pp.8-25
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• 2014

The aims of this study were to determine concentrations of selected metals in Asian and non-Asian dust collected in Daejeon, Korea between February 2008 and December 2008 and to estimate the pollution level. The geochemical analyses of Asian dust (AD) and Non Asian dust (NAD) show that the mean concentrations of As, Cd, Cu, Pb, Zn, Zr, Sb, Mo and S reached levels up to 16, 209, 31, 43, 81, 28, 31, 122 and 302 times higher, respectively, than those in uncontaminated Chinese desert soils. These results indicate that both AD and NAD serve as an atmospheric repository for trace and heavymetal accumulation. The the enrichment factor (EF) and pollution index (PI) show that AD and NAD were severely contaminated by S, Mo, Zr, Cd, Pb, Zn, Sb, Cu, and As. All indices for these metals showed either strong or notably high level of pollution relative to Chinese desert soil, principally due to the severe atmospheric pollution derived from anthropogenic activities in heavily industrial Chinese cities. Therefore, Mo, Cd, Zr, As, Cu, Sb, Pb, and Zn are the ones most strongly affected by anthropogenic inputs such as airborne pollutants.