• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.299-303
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• 1991

A lamp heated LPCVD equipment has been made. Wafer is heated by an array of fifteen tungsten halogen lamps above the front side of a wafer and pyrometer views the back side of the wafer through $CaF_2$ window. Reactor which consisits of a quartz window and a water cooled-stainless steel plate can be evacuated to $5{\times}10^{-3}$ torr with a rotary vane pump. By pyrolysis of $SiH_4$ at about $600^{\circ}C$, polysilicon has been formed on the silicon dioxide film. The measured results show that thickness nonuniformity is 15% and temperature nonuniformity is 1.1%. Because activation energy of pyrolysis of $SiH_4$ is very high, about 1.8eV, small temperature variation will induce large thickness nonuniformity. The main cause of temperature nonuniformity is unsymmetry of lamp power and an unbalanced cooling structure. Charls & Evans' SIMS result shows that the oxygen content in the deposited polysilicon is comparable to that of silicon substrate but carbon content is ten times higher.

• Applied Microscopy
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• v.21 no.2
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• pp.67-75
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• 1991

[ $C_{60}$ ] molecule, the Buckminsterfullerene, has generated great interest because of its unique molecular structure and of superconductivity exhibited in its alkali-doped solids. We have investigated the molecular stacking and crystal structure of $C_{60}$ thin crystals formed on amorphous carbon film. The $C_{60}$ powder which was chromatographically purified was dissolved in benzene. The thin crystals of $C_{60}$ were observed with a 300 keV transmission electron microscope. Electron diffraction analysis and direct imaging of its molecular stacking were carried out. It was found from this work that the molecules of $10.0{\AA}$ diameter are arrayed hexagonally on substrate surface and $8.7{\AA}$ lattice planes are quite often found in several types of ED patterns, which can never be explained with a fcc model. Therefore the structure of $C_{60}$ thin crystals is hcp, although we cannot fully exclude the possibility of co-existence of hcp and fcc.

• Design & Manufacturing
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• v.6 no.1
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• pp.24-28
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• 2012

Friction and wear affect all processes involved in the extraction of materials and their conversion into finished products in the die applications such as drawing, extrusion etc. Originating phenomenon from the contact surface between the tool and workpiece, they are usually a hindrance to materials process operations which usually result in damaging the tools, increasing energy consumption, the contamination of processed material by wear particles and also some problems associated with technologies to control friction and wear. The most well established method to control friction and wear is by the application of lubricant such as fluorocarbon. Besides, a surface technique so-called surface modification can be applied to solve the tribology problems of the die applications for both the economical and ecological reasons. In this article, we applied DLC(diamond-like carbon) thin film on alumina ceramic for HT test using the PIID(plasma ion immersion deposition), 4 groups of test specimens were tested up to $200^{\circ}C$ which is a little higher than the normal working temperature of die application. Pin-on-disc tribo-tester was used to test the friction and surfaces were characterized by SEM and EDS and else, the morphology changes of DLC coatings were studied. The present work indicated that the DLC had a great potential to reduce the friction and wear in the alumina die application without lubricants.

• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.1-15
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• 1997

Titanium oxide films were prepared by ion beam enhanced deposition where the films were synthesized by deposition titianium atoms and simultaneously bombarding with xenon ion beam at an energy of 40 keV in an $O_2$ environ,ent. Structure and composition of titanium oxide films were investigated by X-ray Doffractopm (XRD) Ritjerfprd Backscattering Spectroscopy (RBS) and X-ray Diffraction(XRD) Rutherford Backscattering Spectroscopy (RBS) and X-ray photoelectron spectroscopy (XPS) The results show that thestructure of the prepared films exhibit a rutile phase structure wit high(200) orientation and the O/Ti ratio of the titanium oxide films was about 2:1 XPS anlysis shows that $Ti^{2+},Ti^{3+}\;and\;Ti^{4+}$ chemical states exist on the titanium oxide films. the blood compatibility of the titanium oxide films was studied by measurements of blood clotting time and platelet adhesion. The results show that the anticoagulation property of titanium oxide films improved significantly and better than that of LTI-carbon which was widely used to fabricate artificial heart valve.

• International Journal of Safety
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• v.4 no.2
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• pp.24-29
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• 2005

An experimental study was presented for extinguishing characteristics of liquid fuel fire by water mist($Dv_{0.99}{\leq}200{\mu}m$) containing potassium acetate and sodium acetate trihydrate. To evaluate the extinguishing performance of water mist containing additives, the evaporation characteristics of a water droplet on a heated surface was examined. The evaporation process was recorded by a charge-coupled-device camera. Also, small-scale extinguishing tests were conducted for n-heptane pool fire in ventilated space. During the experiments, flame temperatures were measured, and concentrations of oxygen and carbon monoxide were analyzed by a combustion gas analyzer. The average evaporation rate of water droplet containing additives was lower than that of pure water at a given surface temperature and decreased with the concentration increase due to the precipitation of salt in the liquid-film and change of surface tension. In case of using additives, the fire extinguishing times was shorter than that of pure water at a given discharge pressure and it was because the momentum of a water droplet containing additives was increased. And also dissociated metal atoms, potassium or sodium, were reacted as a scavenger of the major radical species OH, H which were generated for combustion process. Moreover, at a high pressure of 4 MPa, the fire was extinguished through blowing effect as well as primary extinguishing mechanisms.

• 한국가스학회:학술대회논문집
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• 2001.10a
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• pp.58-68
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• 2001

Microbiologically influenced corrosion (MIC) of carbon steel gas pipeline in soil environments was investigated at field and laboratory MIC is very severe corrosion and it is not easy to distinguish this corrosion from Inorganic corrosion because of its localized, pitting-type character Therefore, it is important to provide proper assessment techniques for the prediction, detection, monitoring and mitigation of MIC. It is possible to predict the MIC risk, i.e., the activity of sulfate-reducing bacteria (SRB) through the analysis of soil environments. Chemical, microbiological and surface analysis of corrosion products and metal attacked could reveal the possibility of the occurrence of MIC. Various electrochemical and surface analysis techniques could be used for the study of MIC. Among these techniques, thin-film electrical resistance (ER) type sensors are promising to obtain localized corrosion rate of MIC induced by SRB. It is also important to study the effect of cathodic protection (CP) on the MIC In case of coated pipeline, the relationship between coating disbondment and the activity of SRB beneath the disbanded coating is also important.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.4
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• pp.123-130
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• 2013

Zirconia is well known in industrial applications for its mechanical characteristics. DLC (diamond-like carbon) have high elastic modulus, high electric resistivity, high dielectric constant, high wear resistance, low friction coefficient, bio compatibility, chemically inert and thermally stable. Because of all these physical and chemical properties these types of coatings have become key procedure for thin coating. Friction coefficient of DLC films is already evaluated and the current work is a further advancement by calculating the fracture toughness and wear resistance of these coatings. In the present study DLC thin film coatings are developed on $ZrO_2$ alloy surface using Plasma Enhanced Chemical Vapor Deposition (PECVD) method. Vicker hardness test is employed and it was concluded that, DLC coatings increase the Vickers hardness of ceramics.

• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.836-844
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• 2009

A denitrification bacterium was isolated from riverbed soil and identified as Ochrobactrum sp., whose specific enzymes for denitrification metabolism were biochemically assayed or confirmed with specific coding genes. The denitrification activity of strain G3-1 was proportional to glucose/nitrate balance, which was consistent with the theoretical balance (0.5). The modified graphite felt cathode with neutral red, which functions as a solid electron mediator, enhanced the electron transfer from electrode to bacterial cell. The porous carbon anode was coated with a ceramic membrane and cellulose acetate film in order to permit the penetration of water molecules from the catholyte to the outside through anode, which functions as an air anode. A non-compartmented electrochemical bioreactor (NCEB) comprised of a solid electron mediator and an air anode was employed for cultivation of G3-1 cells. The intact G3-1 cells were immobilized in the solid electron mediator, by which denitrification activity was greatly increased at the lower glucose/nitrate balance than the theoretical balance (0.5). Metabolic stability of the intact G3-1 cells immobilized in the solid electron mediator was extended to 20 days, even at a glucose/nitrate balance of 0.1.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.67-72
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• 2004

A regenerative cooling system has been designed through empirical 1-D analysis for a liquid rocket engine of 30-ton-level thrust. The hot-gas-side wall temperature from 1-D analysis shows 100K difference compared to 3D CFD analysis. Two variations of design with same cooling performance are suggested for different maximum channel widths i.e., 4mm and 2mm. The coolant pressure drop of the latter design is higher by 20%. The maximum liner temperature is about 700K when TBC and the thermal resistance of carbon deposit are considered. So film cooling is recommended to increase the cooling capacity as the present cooling capacity is insufficient

• Journal of the Korean Applied Science and Technology
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• v.15 no.4
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• pp.57-62
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• 1998

In this study, a new conducting materials, namely, a Schiff base (polymeric azomethine) was synthesized from 2,6-diamino-N-docosyl pyridinium bromide and terephthalaldehyde to obtain a soluble and fusible conducting polymer. The synthesized Schiff base structure was analyzed by using UV/vis absorption spectrophotometer, FT-IR spectrometer and $^1H$-NMR spectrometer. It was found that the Schiff base was successfully synthesized and soluble in carbon tetrachloride$(CC^{14})$, its Langmuir-Blodgett film was easily fabricated, and its surface pressure was determined to be 30mN/m for solid state by measuring ${\pi}$-A isotherm.