• Korean Chemical Engineering Research
• /
• v.49 no.5
• /
• pp.652-656
• /
• 2011

Thin film of titania nanotubes(TNT) and titania nanofilms(TNF) was fabricated by anodizing for the study of the photo-catalytic reaction(PC) and photoelectrocatalytic reaction(PEC). Removal efficiency of methylene blue was investigated by UV radiation on the TNT coated titanium plate. Removal efficiency was increased with longer TNT length. Degradation efficiency of the PEC reaction was less sensitive than that of PC reaction. And Effect of TNT length is relatively small. Titania nanofilms(TNF) showed low efficiency than TNT. The efficiency drop of PC was larger than that of PEC.

• Applied Chemistry for Engineering
• /
• v.16 no.3
• /
• pp.361-365
• /
• 2005

Cement-reinforcing carbon fibers were surface-modified with $O_2$, $H_2O$, acrylic acid, diaminocyclohexane plasmas and their effects were investigated. Hydrophobic surfaces with water contact angles of $75{\sim}80^{\circ}$ were changed to hydrophilic surfaces. The water contact angles were reduced down to lower than $10^{\circ}$. As a result, the fiber's hygroscopic property and dispersion in water were improved. Also, Zeta potential of the fiber in water was changed from a negative value to positive values. As a result, adhesion with cement that had a negative Zeta potential was improved up to 57~124% through increased electrostatic interaction.

• Journal of KIISE:Software and Applications
• /
• v.30 no.7_8
• /
• pp.752-763
• /
• 2003

In the large scale B2B transaction like buying ´Express-Train´ or selling ´Daewoo Motor`, a tremendous amount of variables and factors of chaos functionate in it directly or indirectly. To get the effective information processing on the so called complex system like this, it should be possible to unite the human´s ability on the implicit information processing and the agent´s ability on the explicit information processing. In this paper, we suggested a union model for uniting these two heterogeneous abilities and showed how the suggested model can be used for processing the information of such a complex system as B2B negotiation.

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2012.03a
• /
• pp.67-67
• /
• 2012

식생활 및 사회 환경 변화에 따라 식품 폐기물이 많이 발생하고 있다. 이 폐기물을 처리하는 데 막대한 비용이 소요되고 환경오염도 심각한 상황이다. 이에 식품 폐기물의 자원화를 통해 자원의 부가가치를 높이고, 처리비용 절감과 함께 환경오염 방지, 새로운 유기소재의 확보 등의 효과를 볼 것으로 사료된다. 본 연구는 바나나 껍질로부터 추출한 물질의 다양한 기능성을 조사하고, 인디고의 환원제로서 유효성을 확인하여 천연염색 분야에 식품 폐기물의 활용 방안을 모색하는데 목적이 있다. 이를 위하여 바나나 껍질은 건조 후 증류수로 $100^{\circ}C$에서 1시간 동안 추출, 농축하여 분말로 만들어 사용하였다. 바나나 껍질 추출물의 기능성을 알아보기 위해 총당분석(Phenol- sulfuric method), 항산화(DPPH radicals 소거활성), 황색포도상구균에 대한 항균성 실험(Paper disc diffusion)을 하였다. 또한 인디고 염색시 화학환원제 대신 이 분말을 사용하였고, 그 환원력 측정은 환원 포텐셜과 염색 실험을 통해 평가하였다. 본 연구에서 제조한 바나나 껍질 추출물은 항산화능이 우수하였고, 높은 당 함량을 나타냈다. 황색 포도상구균에 대한 항균성을 지녀 향후 기능성 물질로서 응용가능성이 클 것으로 전망된다. 바나나껍질 추출물은 합성인디고 환원에 효과적이었다. 인디고 환원은 바나나껍질 추출물을 첨가하면서 바로 시작되고, 24시간 경과 후 최대 염착량과 최고 전압값을 나타냈다. 바나나 껍질 추출물의 농도가 높아질수록 인디고 환원력은 높아지고 염착량도 증가하는 것으로 나타났다. 따라서 바나나 껍질 추출물은 인디고 환원에서 화학물질인 하이드로설파이트를 대체하여 사용할 수 있는 효과적인 천연유기환원제로 사용할 수 있을 것으로 기대된다.

• International Journal of Highway Engineering
• /
• v.3 no.4 s.10
• /
• pp.105-116
• /
• 2001

This study was performed to evaluate the characteristics of waste foundry sand (WFS) and the asphalt mixture made of a foundry waste sand. To estimate the applicability of WFS, chemical and physical properties were measured by XRF(X-ray fluorescent), and SEM(Scanning electronic microfilm). To improve the stripping resistance of WFS asphalt mixture, anti-stripping agents (a hydrated lime and a liquid anti-stripping agent) were used. To improve tensile properties and durability of WFS asphalt concrete mixture, LDPE(low-density polyethylene) was used as an asphalt modifier Marshall mix design, indirect tensile strength, tensile strength ratio(TSR) after freezing and thawing, moisture susceptibility and wheel tracking tests were carried out to evaluate performance of WFS asphalt concrete. Comparing with conventional asphalt concrete, WFS asphalt concretes showed similar or the better qualify in mechanical properties, and satisfied all specification limits. Therefore, it Is concluded that waste foundry sand can be recycled as an asphalt pavement material.

• Journal of the Korean Chemical Society
• /
• v.47 no.6
• /
• pp.608-613
• /
• 2003

In order to remove particles on surface of post-oxide CMP wafer, new cleaning solution was prepared by mixing with DHF (Diluted HF), nonionic surfactant PAAE (Polyoxyethylene Alkyl Aryl Ether), DMSO (Dimethylsulfoxide) and D.I.W.. Silicone wafers were intentionally contaminated by silica, alumina and PSL (polystylene latex) which had different zeta potentials in cleaning solution. This cleaning solution under megasonic irradiation could remove particles and metals simultaneously at room temperature in contrast to traditional AMP (mixture of $NH_4OH,\;H_2O_2$ and D.I.W) without any side effects such as increasing of microroughness, metal line corrosion and deposition of organic contaminants. This suggests that this cleaning solution would be useful future application with copper CMP in brush cleaning process as well as traditional post CMP cleaning process.

• Journal of the Korean Chemical Society
• /
• v.33 no.1
• /
• pp.31-36
• /
• 1989

The second-order rate constants for the nucleophilic substitution reactions of para-substituted benzyl nitrates with para-substituted anilines in acetonitrile were conductometrically determined. Hammett ${\rho}$x and ${\rho}$y values and Bronsted ${\beta}$ values were obtained from these kinetic data. The reactions of Benzyl nitrates with the series of anilines showed linear Hammett plots with negative slopes. For the change of substituents in the benzyl nitrates, nonlinear Hammett plots with a concave upwards curve were obtained. We applied the potential energy surface and the quantum mechanical models in order to examine the transition state variations caused by changes in substituents on the nucleophile and the substrate. The results showed that the reaction was proceeded via the $S_{N}2$-type reaction mechanism in which the extent of bond-formation was greatly changed depending on the property of the substituents in substrate.

• Journal of the Korean Vacuum Society
• /
• v.17 no.3
• /
• pp.226-233
• /
• 2008

The nucleation and evolution process of Ge nano-islands on Si(001) surfaces grown by chemical vapor deposition have been explored using atomic force microscopy (AFM). The Ge nano-islands are grown by exposing the substrates to a mixture of gasses GeH4 and H2 at pressure of 0.1-0.5Torr and temperatures of $600-650^{\circ}C$. The effect of growth conditions such as temperature, Ge thickness, annealing time on the shape, size, number density, and surface distribution was investigated. For Ge deposition greater than ${\sim}5$ monolayer (ML) with a growth rate of ${\sim}0.1ML/sec$ at $600^{\circ}C$, we observed island nucleation on the surface indicating the transition from strained layer to island structure. Further deposition of Ge led to shape transition from initial pyramid and hut to dome and superdome structure. The lateral average size of the islands increased from ${\sim}20nm$ to ${\sim}310nm$ while the number density decreased from $4{\times}10^{18}$ to $5{\times}10^8cm^{-2}$ during the shape transition process. In contrast, for the samples grown at a relatively higher temperature of $650^{\circ}C$ the morphology of the islands showed that the dome shape is dominant over the pyramid shape. The further deposition of Ge led to transition from the dome to the superdome shape. The evolution of shape, size, and surface distribution is related to energy minimization of the islands and surface diffusion of Ge adatoms. In particular, we found that the initially nucleated islands did not grow through long-range interaction between whole islands on the surface but via local interaction between the neighbor islands by investigation of the inter-islands distance.

• Journal of the Korean Chemical Society
• /
• v.28 no.6
• /
• pp.384-392
• /
• 1984

Reaction of the Fe(II) complex of a fully saturated tetradentate macrocyclic ligand [Fe([14]aneN$_4)(CH_3CN)_2]^{2+}$, where [14]ane$N_4$ represents 1,4,8,11-tetraazacyclotetradecane, with $O_2$ has been investigated in acetonitrile solutions. [Fe([14]aneN$_4)(CH_3CN)_2]^{2+}$ reacts with oxygen to yield low spin Fe(III) species, [Fe([14]aneN$_4)(CH_3CN)_2]^{3+}$, which undergoes metal ion assisted oxidative dehydrogenation of the macrocyclic ligand to produce low spin Fe(II) complex, [Fe([14]tetraeneN$_4)(CH_3CN)_2]^{2+}$. The macrocyclic ligand in [Fe([14]tetraeneN$_4)(CH_3CN)_2]^{2+}$ is highly unsaturated and its double bonds are conjugated. [Fe([14]dieneN$_4)(CH_3CN)_2]^{2+}$ and [Fe([14]dieneN$_4)(CH_3CN)_2]^{3+}$ are isolated as the intermediates of the reaction. The Fe(II) complexes involved in this oxidative dehydrogenation reaction react with carbon monoxide to give respective carbon monoxide derivatives, [FeL$(CH_3CN)(CO)]^{2+}$ (where L = macrocyclic ligand). The values of $v_{CO}$ of [FeL$(CH_3CN)(CO)]^{2+}$, and the electrochemical oxidation potentials of Fe(II) ${\to}$ Fe(III) and the qualitative stability toward air-oxidation for [FeL(CH$_3CN_2)^{2+}$ increase as the degree of unsaturation of the macrocyclic ligands increase.

• Journal of the Korean Electrochemical Society
• /
• v.15 no.4
• /
• pp.236-241
• /
• 2012

It is widely recognized that it is hard to prepare hydrophilic graphite nanoparticles because of their high crystallinity and inert characteristics. In this study, we successfully synthesized the hydrophilic graphite nanoparticles by using liquid phase pulsed laser ablation method which has been actively employed for the thin film deposition up to now. The obtained hydrophilic graphite showed an ultra-high dispersion stability in water, because the hydrophilic functional groups like carboxyl and carbonyl group was simultaneously introduced onto the graphite surface with the nanoparticle formation, as confirmed by FT-IR and zeta potential measurements. Finally, a markedly enhanced gas sensing ability for acetone was shown in comparison with the conventional carbon black for the carbon polymer composite sensor with polyethyleneglycol (PEG).