• 자원리싸이클링
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• 제10권5호
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• pp.8-15
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• 2001

알루미늄드로스는 드로스의 특성과 처리 후 용도를 고려하여 재활용하여야 한다. 본 연구에서는 국내 재생 알루미늄업체에서 발생된 알루미늄드로스를 수산화알루미늄의 원료로 재활용하고자 하였다. 드로스 시료를 크기에 따라 선별하고, $850mu$m 보다 작은 크기의 드로스를 수산화나트륨 용액으로 침출하여 드로스 중의 잔류 알루미늄을 용액 중으로 분리 추출하고, 침출용액에서 석출반응에 의하여 수산화알루미늄 침전물을 회수하였다. 시험 제조한 수산화알루미늄의 순도는 98% 이상이었고, 입경은 $3~39\mu$m 범위였다. 또한, 침출시 드로스의 장입량, NaOH 농도 및 광액농도가 수산화알루미늄의 회수율에 미치는 영향을 조사한 결과 폐드로스를 A/C비 0.5, 광액농도 14~16%로 침출하는 것이 석출시 회수율이 가장 높았다. 본 연구결과를 알루미늄드로스 재활용의 한 가지 방법으로 제안하고자 한다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.1.1-1.1
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• 2011

Printed electronics based on the direct writing of solution processable functional materials have been of paramount interest and importance. In this talk, the synthesis of printable inorganic functional materials (conductors and semiconductors) for thin-film transistors (TFTs) and photovoltaic devices, device fabrication based on a printing technique, and specific characteristics of devices are presented. For printable conductor materials, Ag ink is designed to achieve the long-term dispersion stability and good adhesion property on a glass substrate, and Cu ink is sophisticatedly formulated to endow the oxidation stability in air and even aqueous solvent system. The both inks were successfully printed onto either polymer or glass substrate, exhibiting the superior conductivity comparable to that of bulk one. In addition, the organic thin-film transistor based on the printed metal source/drain electrode exhibits the electrical performance comparable to that of a transistor based on a vacuum deposited Au electrode. For printable amorphous oxide semiconductors (AOSs), I introduce the noble ways to resolve the critical problems, a high processing temperature above $400^{\circ}C$ and low mobility of AOSs annealed at a low temperature below $400^{\circ}C$. The dependency of TFT performances on the chemical structure of AOSs is compared and contrasted to clarify which factor should be considered to realize the low temperature annealed, high performance AOSs. For photovoltaic application, CI(G)S nanoparticle ink for solution processable high performance solar cells is presented. By overcoming the critical drawbacks of conventional solution processed CI(G)S absorber layers, the device quality dense CI(G)S layer is obtained, affording 7.3% efficiency CI(G)S photovoltaic device.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.1985-1988
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• 2014

$Cu_2ZnSnSe_4$ (CZTSe) thin films were synthesized on transparent conducting oxide glass substrates via a simple, non-toxic, and low-cost process using a precursor solution paste. A three-step heating process (oxidation, sulfurization, and selenization) was employed to synthesize a CZTSe thin film as an absorber layer for use in thin-film solar cells. In particular, we focused on the effects of sulfurization conditions on CZTSe film formation. We found that sulfurization at $400^{\circ}C$ involves the formation of secondary phases such as $CuSe_2$ and $Cu_2SnSe_3$, but they gradually disappeared when the temperature was increased. The formed CZTSe thin films showed homogenous and good crystallinity with grain sizes of approximately 600 nm. A solar cell device was tentatively fabricated and showed a power conversion efficiency of 2.2% on an active area of 0.44 $cm^2$ with an open circuit voltage of 365 mV, a short current density of 20.6 $mA/cm^2$, and a fill factor of 28.7%.

• Industrial Engineering and Management Systems
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• 제12권3호
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• pp.244-253
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• 2013

In industries, shipping is an important issue in improving the forecasting accuracy of sales. This paper introduces a hybrid method and plural methods are compared. Focusing the equation of exponential smoothing method (ESM) that is equivalent to (1, 1) order autoregressive-moving-average (ARMA) model equation, a new method of estimating the smoothing constant in ESM had been proposed previously by us which satisfies minimum variance of forecasting error. Generally, the smoothing constant is selected arbitrarily. However, this paper utilizes the above stated theoretical solution. Firstly, we make estimation of ARMA model parameter and then estimate the smoothing constant. Thus, theoretical solution is derived in a simple way and it may be utilized in various fields. Furthermore, combining the trend removing method with this method, we aim to improve forecasting accuracy. This method is executed in the following method. Trend removing by the combination of linear and 2nd order nonlinear function and 3rd order nonlinear function is executed to the original production data of two kinds of bread. Genetic algorithm is utilized to search the optimal weight for the weighting parameters of linear and nonlinear function. For comparison, the monthly trend is removed after that. Theoretical solution of smoothing constant of ESM is calculated for both of the monthly trend removing data and the non-monthly trend removing data. Then forecasting is executed on these data. The new method shows that it is useful for the time series that has various trend characteristics and has rather strong seasonal trend. The effectiveness of this method should be examined in various cases.

• 한국응용과학기술학회지
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• 제30권1호
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• pp.183-196
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• 2013

본 연구는 여러 해조류 소재 중에서 국내 생산량이 많고 연소가 뛰어나 수율이 높은 해초액 화합물을 대량생산 실용화가 가능한 것을 목표로 하며, 해조류인 미역 다시마 톳 기타 김 등을 이용하는 것으로서 주로 원료확보는 폐자원 해조류 등을 이용하여 고온에서 Poly step trap식 건류 공정 적용인 탄화공정을 수반함으로서 생성된 해초 액을 개발하는 연구다. 이를 분리 정제하는 기술적 공정을 개발하고 나아가 시제품을 개발하여 농업, 식품, 비료, 의약품 대체화를 추진함과 동시에 제일 문제시 되고 있는 식품 첨가제를 해결함으로서 고 부가치성 창출과 바이오 생물약제 원료로 개발하고자 하였다. 그래서 해초 액을 추출 분리 및 정제연구를 실시하여 화합물 분석실험을 추진하였다. 그리고 목초액과 성분비교 우위성 입증실험을 성분비교실험을 통해서 비교 검증실험을 추진하였다.

• 자원리싸이클링
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• 제14권4호
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• pp.41-46
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• 2005

알루미늄 폐드로스는 알루미늄 용해 시에 발생되는 주요 폐기물로서 주요 성분은 알루미늄이며 또한 상당량의 금속 알루미늄이 잔류한다. 본 연구에서는 국내 재생 알루미늄업체에서 발생된 알루미늄 폐드로스를 수산화나트륨 용액으로 침출하여 폐드로스 중의 잔류 알루미늄을 용액 상으로 침출, 분리시키고, 침출용액 중에서 알루미늄 성분을 수산화알루미늄으로 회수하였으며 침출 여과 시에 발생된 폐드로스 잔사는 수세, 건조, 배소 과정을 거쳐 알루미나질 세라믹 원료로 재활용하였다. 또한, 1일 4톤의 알루미늄 폐드로스를 처리할 수 있는 규모의 파일롯트 플랜트를 건설하였으며, 시운전을 통하여 개발기술의 재현성을 확인함으로써 연구결과의 상용화 가능성을 제시하였다.

• 미생물학회지
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• 제36권1호
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• pp.69-73
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• 2000

Chicory 뿌리에서 Arthrobacter sp. A-6를 배양하여 inulin fructotransferase를 생산하였을 매 균주의 성장속도, 효소의 생산성을 검토하였다. 가공된 치커리 뿌리는 inulin fructotransferase의 crude enzyme solution으로 처리하였을 때 생산되는 di-fructofuranose dianhydride(DFA III)의 양을 chicory 뿌리의 가공방법에 따른 차이를 비교하였다. 우선 standard 배지에서 생산된 효소액으로 10%의 inulin이 포함된 standard inulin용액을 처리하면, 1.14mg/ml의 DFA III가 생산되었다. Chicory뿌리의 전처리방법에 따라, 같은 조건으로 반응을 진행시키는 실험을 통해 각 배지에서의 생산효율을 비교하였다. Chicory뿌리를 washing과 extraction과정을 거치지 않고 그대로 반응시켰을 경우, 2.29 mg/ml의 DFA III가 생산되어 생산성이 가장 높았는데, 이는 세척과정에서 inulin이 유실되지 않으므로, 기질로 작용하는 inulin의 양이 가장 높은 데 기인하는 것으로 생각된다.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.203-207
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• 2018

In this work, we investigate the effects of lithium doping on the electric performance of solution-processed n-type zinc tin oxide (ZTO)/p-type silicon carbide (SiC) heterojunction diode structures. The proper amount of lithium doping not only affects the carrier concentration and interface quality but also influences the temperature sensitivity of the series resistance and activation energy. We confirmed that the device characteristics vary with lithium doping at concentrations of 0, 10, and 20 wt%. In particular, the highest rectification ratio of $1.89{\times}107$ and the lowest trap density of $4.829{\times}1,022cm^{-2}$ were observed at 20 wt% of lithium doping. Devices at this doping level showed the best characteristics. As the temperature was increased, the series resistance value decreased. Additionally, the activation energy was observed to change with respect to the component acting on the trap. We have demonstrated that lithium doping is an effective way to obtain a higher performance ZTO-based diode.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.37-37
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• 2010

Silicate-silsesquioxane or siloxane-silsesquioxane hybrid thin films are strong candidates as matrix materials for ultra low dielectric constant (low-k) thin films. We synthesized the silicate-silsesquioxane hybrid resins from tetraethoxyorthosilicate (TEOS) and methyltrimethoxysilane (MTMS) through hydrolysis and condensation polymerization by changing their molar ratios ([TEOS]:[MTMS] = 7:3, 5:5, and 3:7), spin-coating on Si(100) wafers. In the case of [TEOS]:[MTMS] 7:3, the dielectric permittivity value of the resultant thin film was measured at 4.30, exceeding that of the thermal oxide (3.9). This high value was thought to be due to Si-OH groups inside the film and more extensive studies were performed in terms of electronic, ionic, and orientational polarizations using Debye equation. The relationship between the mechanical properties and the synthetic conditions of the silicate-silsesquioxane precursors was also investigated. The synthetic conditions of the low-k films have to be chosen to meet both the low orientational polarization and high mechanical properties requirements. In addition, we have investigated a new solution-based approach to the synthesis of semiconducting chalcogenide films for use in thin-film transistor (TFT) devices, in an attempt to develop a simple and robust solution process for the synthesis of inorganic semiconductors. Our material design strategy is to use a sol-gel reaction to carry out the deposition of a spin-coated CdS film, which can then be converted to a xerogel material. These devices were found to exhibit n-channel TFT characteristics with an excellent field-effect mobility (a saturation mobility of ${\sim}\;48\;cm^2V^{-1}s^{-1}$) and low voltage operation (< 5 V). These results show that these semiconducting thin film materials can be used in low-cost and high-performance printable electronics.

• 한국전기전자재료학회논문지
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• 제36권6호
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• pp.588-593
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• 2023

The advantage of OTFT technology is that large-area circuits can be manufactured on flexible substrates using a low-cost solution process such as inkjet printing. Compared to silicon-based inorganic semiconductor processes, the process temperature is lower and the process time is shorter, so it can be widely applied to fields that do not require high electron mobility. Materials that have utility as electrode materials include carbon that can be solution-processed, transparent carbon thin films, and metallic nanoparticles, etc. are being studied. Recently, a technology has been developed to facilitate charge injection by coating the surface of the Al electrode with solution-processable titanium oxide (TiOx), which can greatly improve the performance of OTFT. In order to commercialize OTFT technology, an appropriate method is to use a complementary circuit with excellent reliability and stability. For this, insulators and channel semiconductors using organic materials must have stability in the air. In this study, carbon-doped Mo (MoC) thin films were fabricated with different graphite target power densities via unbalanced magnetron sputtering (UBM). The influence of graphite target power density on the structural, surface area, physical, and electrical properties of MoC films was investigated. MoC thin films deposited by the unbalanced magnetron sputtering method exhibited a smooth and uniform surface. However, as the graphite target power density increased, the rms surface roughness of the MoC film increased, and the hardness and elastic modulus of the MoC thin film increased. Additionally, as the graphite target power density increased, the resistivity value of the MoC film increased. In the performance of an organic thin film transistor using a MoC gate electrode, the carrier mobility, threshold voltage, and drain current on/off ratio (I_on/I_off) showed 0.15 cm²/V·s, -5.6 V, and 7.5×10⁴, respectively.