• Biotechnology and Bioprocess Engineering:BBE
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• 제2권2호
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• pp.126-131
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• 1997

The biosorption and desorption of Cr, Cu and Al were carried out using brown marine algae Sargassum fluitans biomass, known as the good biosorbent of heavy metals. The content of alginate bound to light metals could be changed by physical and chemical pretreatment. The maximum uptake of Cr, Cu and Al was independent of the alginate content. The maximum uptaker of Al was two times(mole basis) than those of Cu and Cr. The aluminum-alginate complex was found in the sorption solution of raw and protonated biomass. Most of Cu, Al and light metals sorbed in the biomass were eluted at pH 1.1. However, only 5 to 10% of Cr sorbed was eluted at pH 1.1. The stoiceometric ion exchange between Cu and Ca ion was observed on Cu biosorption with Ca-loaded biomass. A part of Cr ion was bound to biomass as Cr(OH)2+ or Cr(OH)2+. Al was also bound to biomass as multi-valence ion and interfered with the desorbed Ca ion. The behavior of raw S. fluitans in ten consecutive sorption-desorption cycles has been investigated in a packed bed flow-through-column during a continuous removal of copper from a 35 mg/L aqueous solution at pH 5. The eluant used was a 1%(w/v) CaCl2/HC solution at pH 3.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.414-414
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• 2013

InGaAlAs/InP은 $1.3{\sim}1.55{\mu}m$ 레이저 다이오드 응용을 위한 InGaAsP/InP를 대체하기 위한 물질로 많은 관심을 받아왔다. 디지털 합금 InGaAlAs 다중양자우물(multiple quantum wells: MQWs) 시료는 MBE (molecular beam epitaxy) 장비를 이용하여 n-InP 기판 위에 성장하였다. 양자우물과 장벽은 각각 (InGaAs)0.8(InAlAs)0.2와 (InGaAs)0.4(InAlAs)0.6 SPSs (short-period superlattices)로 $510^{\circ}C$에서 성장하였다. 발광특성을 향상시키기 위하여 질소분위기에서 $700^{\circ}C$ $750^{\circ}C$ 또는 $800^{\circ}C$에서 30초간 열처리(rapid thermal annealing: RTA)하였다. RTA 온도에 따른 디지털 합금 InGaAlAs MQWs의 발광특성을 분석하기 위해 PL (photoluminescence)과 TRPL(time-resolved PL)을 이용하였다. RTA 온도에 따른 InGaAlAs MQWs 시료의 발광 메카니즘 및 운반자 동력학을 연구하기 위하여 발광파장 및 온도에 따른 TRPL을 측정하였다. 저온(10 K)에서 PL 피크는 RTA 온도를 $700^{\circ}C$에서 $750^{\circ}C$로 증가하였을 때 1,242 nm에서 1,245 nm로 장파장 영역으로 이동하였다가 $800^{\circ}C$에서 열처리하였을 때 단파장 영역으로 이동하여 1,239 nm에서 나타났다. 또한 PL 세기는 RTA 온도를 증가함에 따라 증가함을 보이다가 RTA 온도를 $800^{\circ}C$로 증가하였을 때 PL 세기는 감소하였다. 발광소자 개발을 위한 InAlGaAs MQWs 시료의 최적의 열처리 조건을 이러한 PL과 TRPL 결과로부터 결정할 수 있다.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 한국마이크로전자및패키징학회 2000년도 Proceedings of 5th International Joint Symposium on Microeletronics and Packaging
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• pp.118-118
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• 2000

New single-source precursor, [AlCI3:NH2tBu] was synthesized for AlN thin f film processing with AICI3 (Aluminum Chloride) and tBuNH2 (tert-butylamine). AlN thin films for packaging aspplication were deposited on sapphire substrate by a atmosph하ie-pressure MOCVD. In most of other study methyl-based AI precursors w were used for source, But herein Aluminum Chloride was used for as AI source i in order to prevent the carbon contamination in the films and stabilize the p precursor. New precursor showed the very high gas vapor pressure so it allowed to m make the film under atmospheric-pressure and get the high purified film. High q quality AlN thin film was obtained at 700 to $900^{\circ}C$. The new precursor was p purified by a sublimation technique and help to fabricate high purity film. It s showed high vapor pressure, which is able to a critieal factor for the high purity a and atmospheric CVD of AlN. High Quality AIN thin film was obtained at $700-900^{\circ}C$. The AIN film was characterized by RBS

• Journal of Ceramic Processing Research
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• 제21권
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• pp.23-27
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• 2020

The enhanced optical output power of AlGaN/GaN deep ultraviolet light-emitting diodes (UV LEDs) were demonstrated by using the breakdown-induced conductive channels (BICCs). The BICCs could be made by electrical reverse biasing between two adjacent contact pads formed on top p-type layers with a certain distance, causing an electrical breakdown of pn junction and hence a generation of conductive channels. Accordingly, the reflective Ni/Ag/Pt electrodes could be formed simultaneously on the top p-type layer and the other p-type layer with the BICCs, acting as the p- and n-contacts, respectively. The deep UV LEDs fabricated with the BICCs produced the enhanced optical output power by 15 % as compared to the reference LEDs, which were fabricated with the conventional Ti/Al/Ti/Au layers formed on mesa-etched n-type layer. This could be due to the reduced light absorption at the n-contact pads, indicating that the use of BICCs will be very suitable for obtaining better output performance of deep UV emitters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.319-320
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• 2009

In this study, high-quality Al-N doped p-type ZnO thin films were deposited on n-type Si (100) wafer or Si coated with buffer layer by DC magnetron sputtering in the mixture of $N_2$ and $O_2$ gas. The target was ceramic ZnO mixed with $Al_2O_3$ (2 wt%). The p-type ZnO thin film showed higher carrier concentration $2.93\times10^{17}cm^{-3}$, lower resistivity of $5.349\;{\Omega}cm$ and mobility of $3.99\;cm^2V^{-1}S^{-1}$, respectively. According to PL spectrum, the Al donor energy level depth ($E_d$) of Al-N codoped p-type ZnO film was reduced to about 51 meV, and the N acceptor energy level depth ($E_a$) was reduced to 63 meV, respectively.

• Transactions on Electrical and Electronic Materials
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• 제10권3호
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• pp.89-92
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• 2009

High-quality Al-N doped p-type ZnO thin films were deposited on Si and buffer layer/Si by DC magnetron sputtering in a mixture of $N_2$ and $O_2$ gas. The target was ceramic ZnO mixed with $Al_2O_3$ (2 wt%). The p-type ZnO thin films showed a carrier concentration in the range of $1.5{\times}10^{15}{\sim}2.93{\times}10^{17}\;cm^{-3}$, resistivity in the range of 131.2${\sim}$2.864 ${\Omega}cm$, mobility in the range of 3.99${\sim}$31.6 $cm^2V^{-1}s^{-l}$, respectively. It was easier to dope p-type ZnO films on Si substrates than on buffer layer/Si. The film grown on Si showed the highest quality of photoluminescence (PL) characteristics. The Al donor energy level depth $(E_d)$ of Al-N codoped ZnO films was reduced to about 50 meV, and the N acceptor energy level depth $(E_a)$ was reduced to 63 meV.

• Journal of Korea Foundry Society
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• 제17권4호
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• pp.385-392
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• 1997

The main objective of this study is to investigate the microstructure and tensile strength of $SiC_p$/Al alloy composites fabricated by die casting method. Die casting was performed using the preheated mold at the pouring temperature range of $620{\sim}750^{\circ}C$ under the pressure of $1,039 kgf/cm^2$. The low speed and a following high injection speed were 0.4 and 2.1 m/s, respectively. The microstructure of $SiC_p$/Al alloy composites fabricated by die casting method was found to be finer than that of composites fabricated by gravity casting. Also, SiC particulates were homogeneously distributed in refined Al matrix due to rapid solidification. The tensile strength of $SiC_p$/Al alloy composites fabricated by die casting method was found to be varied with cast temperature. The maximun tensile strength of $SiC_p$(10 vol.% and 20 vol.%)/Al alloy composites showed 380 MPa at the cast temperature of $750^{\circ}C$ and 363 MPa at the cast temperature of $700^{\circ}C$, respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1030-1031
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• 2006

Titanium alloys and Titanium alloy-based particulate composites were synthesized using the blended elemental P/M route. First, processing conditions such as the fabrication of master alloy powder were investigated. Ti-6Al-4V, Ti-5Al-2.5Fe, Ti-6Al-2Sn-4Zr-2Mo, IMI685, IMI829, Timetal 1100 and Timetal 62S, and Ti-6Al-2Sn-4Zr-2Mo/ 10%TiB and Timetal 62S/10%TiB were then synthesized using the optimal processing conditions obtained. The microstructures and mechanical properties such as tensile strength and high cycle fatigue strength were evaluated.

• Journal of Korean Society of Water and Wastewater
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• 제12권2호
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• pp.99-105
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• 1998

This research explored the feasibility of preparing and utilizing a preformed polymeric solution of Al(III) for coagulation in water treatment. Slow base(NaOH) injection into supersaturated aluminum chloride solutions did produce high yields of the type of Al polymers useful to water treatment applications. PACl's characteristic analysis showed that the quantity of polymeric Al produced at value of $r(OH_{added}/Al)=2.2$ was 83% of the total aluminum in solution, as showing maximum contents and precipitate was dramatically increased when r was increased above 2.35. And PACl was stable during sitoring period so aging effect was negligible. Results of the coagulation of Nakdong river waters with three PACls showed that the effectiveness of the three coagulants can be considered as r = 2.2 > r = 2.0 > r = 2.35 which are also the order of higher polymeric aluminum contents. Coagulation results for synthetic water exhibited optimum dose of 0.25mM Al, for three PACls, but above optimum dose, r = 2.0 and 2.2 PACl impaired the coagulation and sedimentation of turbidity and humic acid because of the restabilization of particulate. The effect of pH for on coagulation of Nak Dong River water showed that it had much effect turbidity and TOC removal, especially near pH 7. But pH effect was little for turbidity and TOC removal when r = 2.35 PACl was used for coagulation, that PACl had much more precipitates content.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.675-678
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• 2004

[ $CuAlO_2$ ] was used as P-type transparent conducting oxide. $CuAlO_2$ ceramics was obtained from heating a stoichiometric mixture of $Cu_2O$ and $Al_2OH_3$ at $1200^{\circ}C$ for 6h. $CuAlO_2$ ceramics were doped by the rate of 0, 5, 7 and 10% of the $BeSO_4{\cdot}4H_2O$. Sintered ceramics were investigated by X-ray diffraction (XRD) and electrical measurements. The room temperature conductivity of the ceramics, which were doped with $BeSO_4{\cdot}4H_2O$ 5wt% was of the order of $3.19\times10^{-3}S\;cm^{-1}$, and the density was $4.98g/cm^3$. Therefor the conductivity and density in $BeSO+4{\cdot}4H_2O$ 5wt% were better than other cases. Additionally, Seebeck cofficient measurements revealed that these ceramics were p-type semiconductors and the ceramic conductivity increased with the growth temperature.