• Korean Journal of Materials Research
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• v.25 no.7
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• pp.341-346
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• 2015

The feasibility of obtaining graphitic carbon films on targeted substrates without a catalyst and transfer step was explored through the pyrolysis of the botanical derivative camphor. In a horizontal quartz tube, camphor was subjected to a sequential process of evaporation and thermal decomposition; then, the decomposed product was deposited on a glass substrate. Analysis of the Raman spectra suggest that the deposited film is related to unintentionally doped graphitic carbon containing some $sp-sp^2$ linear carbon chains. The films were transparent in the visible range and electrically conductive, with a sheet resistance comparable to that of graphene. It was also demonstrated that graphitic films with similar properties can be reproduciblyobtained, while property control was readily achieved by varying the process temperature.

• Journal of the Korean Chemical Society
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• v.6 no.1
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• pp.54-60
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• 1962

The water gas shift conversion catalyst prepared by the American Cyanamide Co. was subjected to fluidization in a 2-in. Pyrex glass tube to obtain the basic fluidization characteristic data. The size of the catalyst charged ranged from 70 to 120 meshes and it was supported on a single layer 300-mesh wire gauze through which the fluidizing medium, the air, was passed. Following are some data and facts found by the authors: (1) The catalyst particles were porous, and their surfaces were trough and irregular. (2) The average effective particle density and the average shape factor of these particles were 152.2 lb/$ft^3$ and 0.865 respectively. (3) As the particle diameter of the catalyst increased, the minimum fluid voidage of the bed decreased slightly. (4) Just before the incipient fluidization, pressure drop suddenly fell and the bed expanded simultaneously. (5) After fluidization set in, the expansion characteristics of the catalyst bed were similar to those of sand and glass beads except intense bubbling in the catalyst bed.

• Restorative Dentistry and Endodontics
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• v.7 no.1
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• pp.71-75
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• 1981

Five different labelled composite resin, Hypol (Korea), Glass-Ionomer (Japan), Simulate (U.S.A.), Durafil (U.S.A.) and Microfil (U.S.A.) were collected to employ for this experimental study. The purpose of the study is to determine the effect of finger pressure technic and traditional filling by means of plastic instruments on porosity formation in composite materials. Each material with pressure and non-pressure cases were carefully examined under electron microscope. Following were the results obtained through the study. 1. Pressured cases showed smaller number of porosity and the size of porosity was significantly smaller than non-pressured cases in each mateial. 2. Glass-Ionomer with pressure cases were seen as tube-like appearance because of pressured small porosities communicate in a certain direction. 3. Durafil cases both pressured and non pressured, appeared the least porosity formation. among the materiats. 4. Border line between the outmost periphery of the porosity and matrix of the resin in both pressured or non-pressured eases were found characteristically clear in Mierofil cases.

• Progress in Superconductivity and Cryogenics
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• v.11 no.2
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• pp.37-40
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• 2009

A mixed working fluid has a potential to widen the operation temperature range of the thermosiphon. In this study, the thermosiphon using $N_2\;and\;CF_4$ mixture as the working fluid is fabricated and tested to verify its transient thermo hydraulic characteristic. A transparent pyrex glass tube was used for the thermosiphon itself and the vacuum chamber was also fabricated by glass to visualize the internal state of thermo siphon. Onset of condensation temperature was related to the partial pressure of $CF_4$. Two solidifications were observed and condensate temperature range of mixed working fluid was from 160K to 70.7K with $N_2$ 25% composition.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.2
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• pp.145-151
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• 1997

In this paper, we discuss the cathode ray tube(CRT) glass bulb stress and sagging recovery by the contact band pressure using finite element method. We analyzed the band pressure and stress using contact element method between band and bulb before and after banding process which was conducted to decrease the stress concentration using finite element method, and calculated sagging recovery. The analysis results were confirmed by experiments using strain gauge and sagging recovery test apparatus.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2182-2185
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• 1999

In this experimental study we propose the double dielectric barrier discharge(DDBD) reactor to produce as high an electric field as possible. DDBD reactor is designed to remove $NO_x$ at atmospheric pressures from the moving pollution source such as diesel automobile DDBD reactor consisted of two cylinder glass tubes arranged so that the gas flow was directed between the two tubes. Inside of the inner tube was filled with small metal beads and outside of the inner tube was wounded with stainless wire to form the electrode. The outer tube was surrounded by an aluminum foil In this reactor there are three electrodes, i.e. metal bead(C), helical wire(I) and aluminum foil(0). By using DDBD reactor we will report some interesting results of treatment of the gas which is the dilute mixtures of NO in N2. And then we compared thee results with the results of cylinder-wire(CW) which is one of popularly used reactor in non-thermal plasma applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.44-47
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• 2003

In this paper, the electric field distribution in dielectric tube with one layer and spherical dielectric($ZrO_2$) in water was simulated. The reactor was made up of the spherical dielectric that is diameter : 3.0[mm], $ZrO_2(\varepsilon_r:10)$ and one glass plate of thickness(2[mm]), $\varepsilon_r$(10) as electrode. The discharge gap was 8[mm]. To get more strong electric field, the dielectric constant should be higher comparatively. Using the spherical dielectric for water discharge in dielectric tube, the location of equipotential line was shifting from the interior to the exterior. At real water discharge experimental, ozone was measured higher dissolved ozone in water at condition of water rate(l[l/min]) and injector than condition of non-injector or 2~3[l/min].

• Composites Research
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• v.22 no.4
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• pp.1-12
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• 2009

In this paper, quasi-static crushing tests of composite circular tubes under axial compression load are conducted to investigate the energy absorption characteristics. Circular tubes used for this experiment are glass/epoxy (GFRP) composite tubes which are fabricated by the filament winding method. One edge of the composite tube is chamfered to reduce the initial peak load and to prevent catastrophic failure during crushing process. Energy absorption characteristics vary significantly according to the constituent materials, fabrication conditions, tube geometry and test condition. In tube geometry, according as inner diameter increase, unstable crush mode is caused by local buckling of delamination, but control of the fiber orientation should help composite tubes get stable crush mode.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.565-572
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• 2004

The mechanical behavior of concrete-filled glass fiber reinforced polymer columns is affected by various factors including concrete strength, stiffness of tube, end confinement effect, and slenderness ratio of members. In this research the behavior of slender columns was examined both experimentally and analytically. Experimental works include 1) compression test with 30cm long glass fiber composite columns under different end confinement conditions, 2) uni-axial compression test for 7 slender columns, which have various slenderness ratios. Short-length stocky columns gave high strength and ductility revealing high confinement action of FRP tubes. The strength increment and strain change were examined under different end confinement conditions. With slender columns, failure strengths, confinement effects, and stress-strains relations were examined. Through analytical work, effective length was computed and it was compared with the amount of reduction in column strength, which is required to predict design strength with slender specimens. This study shows the feasibility of slender concrete-filled glass fiber reinforced polymer composite columns.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1331-1334
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• 2004

The research on electromagnetic shielding has been advanced for military applications as well as for commercial products. Utilizing the reflective properties and absorptive properties of shielding material, the replied signal measured at the rear surface or at the signal source can be minimized. The shielding effect was obtained from materials having special absorptive properties or from structural characteristics such as stacking sequence. Recently researchers studied the electromagnetic properties of nano size particles. In this research {glass fiber}/{epoxy}/{nano particle} composites(GFR-Nano composites), was fabricated using various nano particles, and their properties in electromagnetic shielding were compared. For the visual observation of the nano composite materials, SEM(Scanning Electron Microscope) and TEM(Transmission Electron Microscope) were used. For the measurement of electromagnetic shielding, HP8719ES S-parameter Vector Network Analyser System was used on the frequency range of 8 GHz～12GHz. Among the nano particles, carbon black and Multi-Walled Carbon Nano-Tube (MWCNT) revealed outstanding electromagnetic shielding. Although silver nano particles (flake and powder) were expected to have effective electromagnetic shielding due to their excellent electric conductivities, test showed little shielding effect.