• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2167-2170
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• 2013

A low-cost and simple recycling process of waste thermoelectric modules has been investigated using chemical reduction methods. The recycling is separated by two processes, such as dissolving and reduction. When the waste thermoelectric chips are immersed into a high concentration of $HNO_3$ aqueous solution at $100^{\circ}C$, oxide powders, e.g., $TeO_2$ and $Sb_2O_3$, are precipitated in the $Bi^{3+}$ and $HTeO{_2}^+$ ions contained solution. By employing a reduction process with the ions contained solutions, $Bi_2Te_3$ nanoparticles are successfully synthesized. Due to high reduction potential of $HTeO{_2}^+$ to Te, Te elements are initially formed and subsequently $Bi_2Te_3$ nanoparticles are formed. The average particle size of $Bi_2Te_3$ was calculated to be 25 nm with homogeneous size distribution. On the other hand, when the precipitated powders reduced by hydrazine, $Sb_2O_3$ and Te nanoparticles are synthesized because of higher reduction potentials of $TeO_2$ to Te. After the washing step, the $Sb_2O_3$ are clearly removed, results in Te nanoparticles.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 Proceedings of The 6th korea-china joint workshop on nuclear waste management
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• pp.86-91
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• 2005

A metal product obtained from an electrolytic reduction process, possesses less volume and radioactivity than those of the unprocessed spent oxide fuels. The chemical composition of the metal product varies according to the process condition. In this work, a basic study was performed to evaluate the chemical forms of the spent oxide fuel components in an electrolytic reduction process with the operation conditions. One of the most important operation conditions is the cell potential applied for the reduction cell. It is expected that $PU_{2}O_3$ is difficult to reduce even though the cell potential is negative enough to reduce the lithium oxide when the activity of $Li_{2}O$ exceeds 0.003. The reduction of actinide oxides via the reduction of $Li_{2}O$ is assumed to have a greater reduction yield than a direct reduction of the actinide oxides.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.290.1-290.1
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• 2016

Grapehen, a single atomic layer of graphite, has been in the spotlight and researched in vaious fields, because its fine mechanical, electrical properties, flexibility and transparence. Synthesis methods for large-area graphene such as chemical vaper deposition (CVD) and mechanical, chemical exfoliation have been reported. In particular, chemical exfoliation method receive attention due to low cost process. Chemical exfoliation method require reduction of graphene oxide in the process of exfoliation such as chemical reduction by strong reductant, thermal reduction on high temperature, and optical reduction via ultraviolet light exposure. Among these reduction methods, optical reduction is free from damage by strong reductant and high temperature. However, optical reduction is economically infeasible because the high cost of short-wavelength ultraviolet light sorce. In this paper, we make graphene-oxide and lanthanoid ion mixture aqueous solution which has highly optical absorbency in selective wevelength region. Sequentially, we synthesize reduced graphene oxide (RGO) using the solution and visible laser beam. Concretely, graphene oxide is made by modified hummer's method and mix with 1 ml each ultraviolet ray absorbent Gd3+ ion, Green laser absorbent Tb3+ ion, Red laser absorbent Eu3+ ion. After that, we revivify graphene oxide by laser exposure of 300 ~ 800 nm layser 1mW/cm2 +. We demonstrate reproducibility and repeatability of RGO through FT-IR, UV-VIS, Low temperature PL, SEM, XPS and electrical measurement.

• Bulletin of the Korean Chemical Society
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• 제8권5호
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• pp.414-418
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• 1987

Electrochemical reduction of dibenzoylmethane was studied on mercury electrode by means of cyclic voltammetry, polarography and potentiostatic measurements in ethanol-water system. In acidic solutions monomeric pinacol was produced by irreversible two-electron process while monomeric and dimeric pinacol were competitively produced by the same process in neutral solution. However, in basic solution the dimeric pinacol was mostly produced through radical by irreversible one-electron transfer process. Mechanisms of the reduction of dibenzoylmethane are deduced from Tafel slope, pH dependance and reaction order with respect to the concentration of dibenzoylmethane in the solution of various pH.

• Korean Chemical Engineering Research
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• 제49권6호
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• pp.764-768
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• 2011

모노에탄올아민(MEA)으로 대표되는 습식 아민을 이용한 이산화탄소 포집 공정은 기술적 신뢰도가 높아 초기 CCS(Carbon Capture & Storage) 시장을 주도할 것으로 전망된다. 다만 흡수제 재생에 에너지 소비가 많은 점이 단점으로 지적 받고 있어 흡수제 재생 에너지 절감을 위한 다양한 공정 개선안이 연구되고 있다. 본 논문에서는 MEA 공정에서 흡수탑으로 유입되는 배가스를 분할 유입하는 공정 개선안을 제안 하고 시뮬레이터를 이용한 공정모사를 통하여 그 효과를 보였다. 배가스를 분할 유입한 결과 흡수탑 하단부에서 냉각효과가 있었고 이로 인해 흡수제 유량이 감소하였다. 배가스 분할 비와 분할 유입 단 높이를 변경하며 최적 분할 조건을 찾았으며 이때 흡수제 유량은 6.4%, 재생 에너지는 5.8% 감소하였다.

• 한국분말재료학회지
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• 제23권4호
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• pp.297-302
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• 2016

Ag nanoparticles are extensively studied and utilized due to their excellent catalysis, antibiosis and optical properties. They can be easily synthesized by chemical reduction methods and it is possible to prepare particles of uniform size and high purity. These methods are divided into vapor methods and liquid phase reduction methods. In the present study, Ag particles are prepared and analyzed through two chemical reduction methods using solvents containing a silver nitrate precursor. When Ag ions are reduced using a reductant in the aqueous solution, it is possible to control the Ag particle size by controlling the formic acid ratio. In addition, in the Polyol process, Ag nanoparticles prepared at various temperatures and reaction time conditions have multiple twinned and anisotropic structures, and the particle size variation can be confirmed using field emissions scanning electron microscopy and by analyzing the UV-vis spectrum.

• Current Photovoltaic Research
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• 제6권2호
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• pp.49-55
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• 2018

Recently solar cell industry needs the optimal design of Czochralski process for low cost high quality silicon mono crystalline ingot. Because market needs both high efficient solar cell and similar cost with multi-crystalline Si ingot. For cost reduction in Czochralski process, first of all energy reduction should be completed because Czochralski process is high energy consumption process. For this purpose we studied optimal water-cooling tube design and simultaneously we also check the quality of ingot with Von mises stress and V(pull speed of ingot)/G(temperature gradient to the crystallization) values. At this research we used $CG-Sim^{(R)}$ S/W package and finally we got improved water-cooling tube design than normally used process in present industry. The optimal water-cooling tube length should be 200mm. The result will be adopted at real industry.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.505-509
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• 2013

A low temperature ($65^{\circ}C$) thermal deposition process was developed for depositing a silver coating on thermally sensitive polymeric substrates. This low temperature deposition was achieved by chemical reduction of a silver alkylcarbamate complex with latent reducing agent. The effects of acetol as a latent reducing agent for the silver 2-ethylhexylcarbamate (Ag-EHCB) complex and their blend solutions were investigated in terms of reducing mechanism, and the size and shape of silver nanoparticles (Ag-NPs) as a function of reduced temperature and time, and PVP stabilizer concentration were determined. Low temperature deposition was achieved by combining chemical reduction with thermal heating at $65^{\circ}C$. A range of polymer film, sheet and molding product was coated with silver at thicknesses of 100 nm. The effect of process parameters and heat treatment on the properties of silver coatings was investigated.

• Bulletin of the Korean Chemical Society
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• 제15권10호
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• pp.896-900
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• 1994

The pH-dependent reduction behavior of N-monosubstituted-4,4'-bipyridinium ions ($RBPY^+: R=methyl(C_1)$; benzyl; n-octyl; n-dodecyl) has been investigated by electrochemical and spectroelectrochemical techniques. At acidic condition, $RBPY^+$ is protonated and the protonated species are reduced by two consecutive one-electron processes. The $2e^-$ reduced species undergoes a chemical reaction with $H^+$. The second-order rate constant $(k_H)$ of the homogeneous chemical process is $(3.7{\pm}0.3){\times}10^3M^{-1}s^{-1}$ for the two electron reduction product of $C_1BPY^+$. At high pH, the electrode reduction of $RBPY^+$ is one-step $2e^-$ transfer process with concomitant addition of $H^+$, which is confirmed by cyclic voltammetric study using a microdisk electrode.

• Bulletin of the Korean Chemical Society
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• 제11권2호
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• pp.89-94
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• 1990

The redox properties of 2-amino-1-cyclopentene-1-dithiocarboxylate anion (acdc) and its oxovanadium complex, $VO(acdc)_2$ have been investigated in dimethylformamide (DMF) with polarography and cyclic voltammetry. Bis(2-amino-1-cyclopentene-1-dithiocarboxylate) oxovanadium(IV) exhibits two polarographic oxidation waves and two reduction waves in the potential range from +0.50V to - 2.4V vs. the Ag/AgCl (DMF) reference electrode. The second oxidation wave appeared at - 0.08V is found to be reversible and is attributed to the formation of $VO(acdc)_2\;^+$. The first reduction process (at - 0.60V) is also reversible and this reduction process is caused by the electrode process of formation of $VO(acdc)_2$-species. The half wave potential for the reduction, V(IV)$\to$V(III) is more positive for oxovanadium complexes containing sulfur donor atoms than other VO(IV) complexes having oxygen or nitrogen donor atoms.