• 대한화학회지
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• 제37권4호
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• pp.401-407
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• 1993

티타늄 금속판을 공기산화와 수증기 산화하여 만든 $TiO_{2-x}$ 박막을 전극으로 사용하여 1M NaOH 용액에서 전기화학적 성질을 연구하였다. 순환 전압 전류법에 의한 산소의 환원전위는 SCE에 대해 -0.9 ∼ -1.0 V 근처에서 나타났으며 이들 반응은 전체적으로 비가역적으로 진행되었다. 수증기 산화법에 의해 제조된 $TiO_{2-x}$ 전극들의 전기화학적 성질들은 공기 산화법에 의해 제조된 것과 다르게 나타났으며 900$^{\circ}$이상의 온도에서 제조된 전극들은 단결정 $TiO_2$ 전극들의 전기화학적 성질과 비슷하였다. $TiO_{2-x} $전극에서 산소위 환원전위는 flat band 전위보다 더 양전위 쪽에서 나타났으며 pH 증가에 따라 60mV/pH 정도 감소되었다.

• 공업화학
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• 제22권6호
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• pp.664-671
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• 2011

무촉매 공기 브로잉 공정에서 석유계 감압 잔사유로부터 세미-부로운 아스팔트를 제조하는 경우, 시간에 따른 아스팔트의 조성, 구조, 물리적 성질의 변화를 조사하였다. 공기 브로잉에 의해 지방족 탄화수소 성분이 방향족 탄화수소 성분으로 전이되고, 고분자화 되어 아스팔텐 성분이 증가함을 박막크로마토그래피를 이용한 조성 분석에서 관찰하였다. 처리시간에 따른 방향족화와 고분자화 정도의 증가는 $^1H-NMR$, 열시차분석, 그리고 열중량분석에서도 확인할 수 있었다. 이러한 아스팔트의 조성과 구조의 변화는 침입도의 감소, 연화점과 인화점의 증가를 초래하였다.

• 한국표면공학회지
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• 제55권4호
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• pp.215-221
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• 2022

In the present work, copper oxide thin films were formed by heat-treatment method with different temperatures and atmosphere, e.g., at 200 ~ 400 ℃; in air and Ar atmosphere. The morphological, electrical and optical properties of the thermally fabricated Cu oxide films were analyzed by SEM, XRD, and UV-VIS spectrometer. Thereafter, photoelectrochemical properties of the thermal copper oxide films were analyzed under solar light (AM 1.5, 100 mW/cm²). Conclusively, the highest photocurrent was obtained with Cu₂O formed under the optimum annealing condition at 300 ℃ in air atmosphere. In addition, EIS results of Cu oxide formed in air atmosphere showed relatively low resistance and long electron life-time compared with Cu Oxide fabricated in Ar atmosphere at the same temperature. This is because heat-treatment in Ar atmosphere could not form Cu₂O due to lack of oxygen, and thermally formed CuO at high temperature suppressed stability and conductivity of the Cu oxide.

• 한국연소학회지
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• 제6권2호
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• pp.15-22
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• 2001

A pressure-based, unstructured finite volume method has been applied to couple the chemical kinetics and fluid dynamics and to capture effectively and accurately the steep gradient flame field. The pressure-velocity coupling is handled by two methodologies including the pressure-correction algorithm and the projection scheme. A stiff, operator-split projection scheme for the detailed nonequilibrium chemistry has been employed to treat the stiff reaction source terms. The conservative form of the governing equations are integrated over a cell-centered control volume with collocated storage for all transport variables. Computations using detailed chemistry and variable transport properties were performed for two laminar reacting flows: a counterflow hydrogen-air diffusion flame and a lifted methane-air triple flame. Numerical results favorably agree with measurements in terms of the detailed flame structure.

• Bulletin of the Korean Chemical Society
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• 제28권8호
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• pp.1285-1288
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• 2007

Au was electrolessly deposited on polycarbonate (PC) membranes (0.1 μm pores) at the air/water interface. It was found that the Au nanotube dimension can be controlled by adjusting the plating temperature and the solution composition. Interfacial deposition of Au at relatively low temperatures (4℃) produced long nanotubes, which run through the whole membrane thickness with small openings. Increase of plating temperatures resulted in the decrease of nanotube lengths and Au film thicknesses. It was also disclosed that the inside-diameter of Au nanotubes can be controlled with negligible variations in length by changing the composition of a plating solution.

• KIEE International Transactions on Electrophysics and Applications
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• 제11C권3호
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• pp.81-84
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• 2001

The trans and cis forms of N-alkyl-4-styrylpyridinium derivatives (CnSP: n= 4, 8, 12, 16) were successfully synthesized and purified. The derivatives of styrylpyridinium cause photoisomerization when they are illuminated with UV light. The pressure-area isotherms of CnSP and their derivatives were studied to reveal the effect of alkyl chain length. The photoisomerization of CnSP monolayers at the air/water interfaces was indirectly studied by measuring surface tension changes with photoirradiation on the water surface. The characteristics of CnSP were furthermore studied with UV-vis, surface pressure-area isotherms, surface potential-area isotherms, Brewster Angle Microscopy (BAM) at the air/water interface, and optical diffraction efficiency on the ultrathin films.

• Membrane and Water Treatment
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• 제7권4호
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• pp.297-311
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• 2016

Modeling and simulation of air humidification by hollow fiber membrane contactors are investigated in the current study. A computational fluid dynamic model was developed by solving the k-epsilon turbulence 2D Navier-Stokes equations as well as mass conservation equations for steady-state conditions in membrane contactors. Finite element method is used for the study of the air humidification under different operating conditions, with a focus on the humidity density, total mass transfer flux and velocity field. There has been good agreement between simulation results and experimental data obtained from literature. It is found that the enhancement of air stream decreases the outlet humidity from 0.392 to 0.340 (module 1) and from 0.467 to 0.337 (module 2). The results also indicated that there has been an increase in air velocity in the narrow space of shell side compared with air velocity wide space of shell side. Also, irregular arrangement has lower dead zones than regular arrangement which leads to higher water flux.

• Carbon letters
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• 제10권2호
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• pp.114-122
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• 2009

Crushed, depitted peach stones were impregnated activated with 50% $H_3PO_4$ followed by pyrolysis at $500^{\circ}C$. Two activated carbons were produced, one under its own evolved gases during pyrolysis, and the second conducted with air flow throughout the carbonization stage. Physicochemical properties were investigated by several procedures; carbon yield, ash content, elemental chemical analysis, TG/DTG and FTIR spectra. Porosity characteristics were determined by the conventional $N_2$ adsorption at 77 K, and data analyzed to get the major texture parameters of surface area and pore volume. Highly developed activated carbons were obtained, essentially microporous, with slight effect of air on the porous structure. Oxygen was observed to be markedly incorporated in the carbon matrix during the air treatment process. Cation exchange capacity towards Cu (II) and Cd (II) was tested in batch single ion experimental mode, which proved to be slow and a function of carbon dose, time and initial ion concentration. Copper was up taken more favorably than cadmium, under same conditions, and adsorption of both cations was remarkably enhanced as a consequence of the air treatment procedure. Sequestration of the metal ions was explained on basis of the combined effect of the oxygen functional groups and the phosphorous-containing compounds; both contributing to the total surface acidity character.

• 한국염색가공학회지
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• 제18권5호
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• pp.53-60
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• 2006

The 1,3-bis(4-aminoaryl)squaraines showed color, change behavior, they were found to undergo reduction with sodium borohydride in solution to give colorless leuco compounds, which oxidized readily in air back to the colored squaraine dye. We have shown that initial observations indicated that the derivatives synthesized gave new donor-acceptor chromophores. It is also interesting to note than the oxidation of the leuco squaraines did initially produce a species absorbing about 630-680 wavelengths. The 1,3-squaraines have found many uses as near-infrared absorbers, laser dyes and photoconductive materials. Furthermore their color-change redox behavior has potential in the area of peroxidase-based bioassaysas oxidation sensitive indicator systems were investigated.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.2039-2044
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• 2011

A semi-continuous and automated method for quantifying atmospheric ammonia at the parts per billion level has been developed. The instrument consists of a high efficiency diffusion scrubber, an electrolytic on-line anion exchange device, and a conductivity detector. Water soluble gases in sampled air diffuse through the porous membrane and are absorbed in an absorbing solution. Interferences are eliminated by using an anion exchange devises. The electrical conductivity of the solution is measured without chromatographic separation. The collection efficiency was over 99%. Over the 0-200 ppbv concentration range, the calibration was linear with $r^2$ = 0.99. The lower limit of detection was 0.09 ppbv. A parallel analysis of Seoul air over several days using this method and a diffusion scrubber coupled to an ion chromatography system showed acceptable agreement, $r^2$ = 0.940 (n = 686). This method can be applied for ambient air monitoring of ammonia.