• Journal of the Korean Applied Science and Technology
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• v.9 no.2
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• pp.119-126
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• 1992

The kinetics of the hydrolysis of indolylacrylophenone derivatives(IA) was investigated by ultraviolet spectrophotometry in 30% dioxane-$H_2O$ at 25$^{\circ}C$ Rate equations were obtained over a wide pH range. On the basis of rate equation, general base catalysis and Hammett's plot, the mechanism of hydrolysis to the (IA) were proposed: Below pH 3.0, the hydrolysis of (IA) was proportional to hydronium ion concentration, between pH 4.0${\sim}$9.0 neutral water molecule and hydroxide ion were added to carbon-carbon double bond and over pH 10.0 hydrolysis of (IA) was proportional to hydroxide ion concentration.

• Transactions of Materials Processing
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• v.21 no.6
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• pp.354-359
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• 2012

Effects of a nitriding treatment on the tensile and high cycle fatigue properties were investigated by conducting ion-nitriding and gas nitro-caburizing treatments on the spheroidized SCr430B medium-carbon steel and performing tensile and tension-tension high cycle fatigue tests. The nitrided samples showed much lower strength and ductility compared to those in the initial as-spheroidized state and premature fracture occurred at the hardened layers. The micro-voids in the compound layer caused fatigue crack initiation. Thus, the removal of the compound layer with micro-voids remarkably improved the fatigue resistance to even beyond that of the as-spheroidized sample.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.145-152
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• 1992

Si surfaces exposed to CHF3/C2F6 gas plasmas ih reactive ion etching (RIE) have been characterized by X-ray photoelectron spectroscopy (XPS). CHF3/C2F6 gas plasma exposure of Si surface leads to the deposition of residual film containing carbon and fluorine. The narrow scan spectra of C 1s show various bonding states of carbon as C-Si, C-F/H, C-CFx(x $\leq$ 3), C-F, C-F2, and C-F3. The chemical bonding states of fluorine are described with F-Si, F-C and F-O. And the oxygen and silicon are also detected. The effects of parameters for reactive ion etching as CHF3/C2F6 gas ratio, RF power, and pressure are investigated.

• Carbon letters
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• v.11 no.4
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• pp.343-346
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• 2010

The various expanded graphites (EGs) was prepared and applied as anode material for high power Li-ion secondary battery (LIB). By changing the processing conditions of EG, a series of EG with different structure were produced, showing the changed electrochemical properties. The charge-discharge test showed that the initial reversible capacity of EG anodes prepared at the suitable conditions was over 400 mAh/g and the charge capacity at 5 C-rate was 83.2 mAh/g. These values demonstrated the much improved electrochemical properties as compared with those for the graphite anode of 360 mAh/g and 19.4 mAh/g, respectively, showing the possibility of EG anode materials for high power LIB.

• Transactions on Electrical and Electronic Materials
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• v.7 no.6
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• pp.297-300
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• 2006

The response surface modeling of the pretilt angle control using ion-beam (IB) alignment on nitrogen doped diamond-like carbon (NDLC) thin film layer is investigated. This modeling is used to analyze the variation of the pretilt angle under various process conditions. IB exposure angle and IB exposure time are considered as input factors. The analysis of variance technique is settled to analyze the statistical significance, and effect plots are also investigated to examine the relationships between the process parameters and the response. The model can allow us to reliably predict the pretilt angle with respect to the varying process conditions.

• Carbon letters
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• v.5 no.3
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• pp.118-126
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• 2004

MCMB (Mesocarbon microbeads) is a kind of anode material for lithium-ion secondary battery. MCMB charge/discharge cycle stability is one of the important criterion at lithium-ion battery operation. In this study, the cycling stability of a lithium-ion secondary battery has been examined. MCMB was made by the direct solvent extraction method. After the MCMB was carbonized and graphitized, the measurement of charge/discharge capacity and efficiency were carried out. In the result, discharge capacity of MCMB in the initial cycle was above 290.0 mAh/g. After the second cycle, efficiency of charge/discharge MCMB was about 98%. These results were similar to the commercial MCMB product.

• Journal of Ceramic Processing Research
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• v.13 no.spc2
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• pp.363-367
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• 2012

DLC (diamond liked carbon) coating of the tungsten carbide (WC) alloy core surface for molding a glass aspheric lens improves the quality of glass lens and the molding core and is characterized by high hardness, high elasticity, abrasion resistance and chemical stability. In this study, the effect of DLC coating of a thin film by means of the filtered AIP (arc ion plating) technique was examined on Ra and shape of the coated surface. Roughness before and after DLC coating was measured and the result showed that the roughness was improved after coating as compared to before coating. It was observed that DLC coating of the WC alloy core surface for molding had an effect on improving the roughness and shape of the core surface. It is considered that this will have an effect on improving abrasion resistance and the service life of the core surface.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.165-166
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• 2002

Hydrogen free diamond like carbon (DLC) films were prepared on steel substrates by using a single ion beam in a configuration that allowed sputtering of a graphite target and at the same time allowed to impact the substrate at a grazing angle. The DLC films so prepared have improved properties with increased disorder and with modest hardness that is slightly higher than previously reported values. We have studied the effects of $N_2^+$ ions implantation on such films. It is found that the implantations of nitrogen ions into DLC films lead to chemical modifications that allowed N atoms to be incorporated into the carbon network to produce a nitrogenated DLC. Nano-indentation experiments indicated that the nitrogenated films have consistently higher hardnesses ranging from 30 to 45GPa, which represents a considerable increase in surface hardness, compared with non-nitrogenated precursor films. The investigations by XPS and Raman spectroscopy suggests that the $N_2^+$ implanted DLCs had undergone both chemical and structural modifications through the incorporation of N atoms and the increased ratio of $sp^3/sp^2$ type bonding. The observed high hardness was therefore attributable to these structural and chemical modifications. This result has implication for the preparation of super hard wear resistant films required for tribological functions in devices.

• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.376-380
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• 2016

A composite electrode made of iron oxide nanoparticles/multi-wall carbon nanotube (iNPs/M) delivers high specific capacity and cycle durability. At a rate of $200mAg^{-1}$, the electrode shows a high discharge capacity of ${\sim}664mAhg^{-1}$ after 100 cycles, which is ~ 70% of the theoretical capacity of $Fe_3O_4$. Carbon black, carbon nanotube, and graphene as anode materials have been explored to improve the electrical conductivity and cycle stability in Li ion batteries. Herein, iron oxide nanoparticles on acid treated MWCNTs as a conductive platform are combined to enhance the drawbacks of $Fe_3O_4$ such as low electrical conductivity and volume expansion during the alloying/dealloying process. Enhanced performance was achieved due to a synergistic effect between electrically 3D networks of conductive MWCNTs and the high Li ion storage ability of $Fe_3O_4$ nanoparticles (iNPs).

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.175-175
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• 1999

Circumventing problems lying in the conventional lithographic techniques, we devised a new method for the fabrication of nanometer scale metal wires inspired by the unique characteristics of carbon nanotubes (CNTs). Since carbon nanotubes could act as masks when CNT-coated thin Au/Ti layer on a SiO2 surface was physically etched by low energy argon ion bombardment 9ion milling), Au/Ti nano-wires were successfully formed just below the CNTs exactly duplicating their lateral shapes. Cross-sectional analysis by transmission electron microscopy revealed that the edge of the metal wire was very sharply developed indicating the great difference in the milling rates between the CNTs and the metal layer as well as the good directionality of the ion milling. We could easily find a few nanometer-wide Au/Ti wires among the wires of various width. After the formation of nano-wires, the CNTs could be pushed away from the metal nano-wire by atomic force microscopy, The lateral force for the removal of the CNTs are dependent upon the width and shape of the wires. Resistance of the metal nano-wires without the CNTs was also measured through the micro-contacts definted by electron beam lithography. since this CNT-based lithographic technique is, in principle, applicable to any kinds of materials, it can be very useful in exploring the fields of nano-science and technology, especially when it is combines with the CNT manipulation techniques.