• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.549-555
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• 1996

Diamond Like Carbon film is amorphous film which is considered to consist of three coordinate graphite structure and tetrahedron coordinate diamond structure. Its hardness, thermal conductivity and chemical stability are nearly to one of diamond. It is well known to become semi-conductor by doping of inpurity. In this study Diamond Like Carbon film was synthesized by Microwave Plasma CVD in the gas mixture of hydrogen-methan-nitrogen and doped of nitrogen on the single-crystal silicon or silica glass. The temperature of substrate and nitrogen concentration in the gas mixture had an effect on the bonding state, structural properties and conduction mechanism. The surface morphology was observed by Scanning Electron Microscope. The strucure was analyzed by laser Raman spectrometry. The bonding state was evaluated by electron spectroscopy. Diamond Like Carbon film synthesized was amorphous carbon containing the $sp^2$ and $sp^3$ carbon cluster. The number of $sp^2$ bonding increased as nitrogen concentration increased from 0 to 40 vol% in the feed gas at 1233K substrate temperature and at $7.4\times10^3$ Pa. Increase of nitrogen concentration made Diamond Like Carbon to be amorphous and the doze of nitragen could be controlled by nitrogen concentration of feed gas.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.100-105
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• 2014

It has been previously reported that in principle sludge and blockages can be detected and even characterized by using guided ultrasonic torsional waves, based on an idealized model in which the sludge layer was simplified in terms of geometry and material properties. The work revealed that the presence of a layer inside a pipe scatters the guided wave propagating in the pipe and both the reflection and transmission of the guided wave can be used to effectively detect and characterize the layer. This paper proceeds the work by taking into account more realistic sludge characteristics, including irregular circumferential profiles of the sludge layer and imperfect bonding state between the sludge and the pipe. The influence of these issues is investigated to identify the critical factors that influence the detection and characterization capability of the two measurements.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.6
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• pp.345-349
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• 2001

This study has investigated the effect of thermal stability and mechanical property of $Fe_{80-X}P_{10}C_6B_4M_X$(X=2, 4, 6, M=transition metal) amorphous alloys fabricated by the melt-spun process. The glass transition temperature($T_g$), crystallization temperature($T_x$) and hardness increase with decreasing electron concentration (e/a) from about 7.38 to 7.18. The decrease of e/a implies the increase in the attractive bonding state between the M elements and other constituent element. The decrease in a/e leads to the enhancement of the attractive bonding state among the constituent elements which is favorable for the increase in $T_g$, $T_x$ and hardness.

• Proceedings of the KWS Conference
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• 1999.10a
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• pp.236-238
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• 1999

• Proceedings of the KWS Conference
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• v.43
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• pp.46-48
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• 2004

• Journal of Welding and Joining
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• v.24 no.5
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• pp.11-14
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• 2006

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.105-107
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• 2001

• Steel and Composite Structures
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• v.23 no.2
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• pp.187-194
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• 2017

To reuse a broken plain concrete (PC) arch, a retrofitting method was proposed to ensure excellent structural performances, in which carbon fiber reinforced polymers (CFRPs) were applied to repair and strengthen the damaged PC arch through bonding and wrapping techniques. Experiments were carried out to reveal the deformation and the load carrying capacity of the retrofitted composite arch. Based on the experiments, repairing and strengthening effects of the CFRP retrofitted broken arch were revealed. Simplified analysing model was suggested to predict the peak load of the CFRP retrofitted broken arch. According to the research, it is confirmed that absolutely broken PC arch can be completely repaired and reinforced, and even behaves more excellent than the intact PC arch when bonded together and strengthened with CFRP sheets. Using CFRP bonding/wrapping technique a novel efficient composite PC arch structure can be constructed, the comparison between rebar reinforced concrete (RC) arch and composite PC arch reveals that CFRP reinforcements can replace the function of steel bars in concrete arch.

• Journal of Welding and Joining
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• v.33 no.5
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• pp.41-46
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• 2015

The snap cure NCP(non-conducive paste) adhesive material is essentially required for the high productivity flip chip bonding process. In this study, the accessibility of DEA(dielectric analysis) method for the evaluation of snap cure behavior was investigated with comparison to the isothermal DSC(differential scanning calorimetry) method. NCP adhesive was mainly formulated with epoxy resin and imidazole curing agent. Even though there were some noise in the dielectric loss factor curve measured by DEA, the cure start and completion points could be specified clearly through the data processing of cumulation and deviation method. Degree of cure by DEA method which was measured from the variation of the dielectric loss factor of adhesive material was corresponded to about 80% of the degree of cure by DSC method which was measured from the heat of curing reaction. Because the adhesive joint cured to the degree of 80% in the view point of chemical reaction reveals the sufficient mechanical strength, DEA method is expected to be used effectively in the estimation of the high speed curing behavior of snap cure type NCP adhesive material for flip chip bonding.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.24-27
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• 2009

Solid-state dye-sensitized solar cells (DSSCs) have been constructed employing supramolecular electrolytes with multiple hydrogen bonding. A supramolecule was facilely synthesized by one-pot reaction between the amines of methyl isocytosine (MIC) and the epoxy groups of poly(ethylene glycol diglycidyl ether) (PEGDGE) to produce quadruple hydrogen bonding units. Hydrogen bonding interactions and dissolution behavior of salt in supramolecular electrolytes are investigated. The ionic conductivity of the supramolecular electrolytes with ionic liquid, i.e. 1-methyl-3-propylimidazolium iodide (MPII) reaches $8.5{\times}10^{-5}$ S/cm at room temperature, which is higher than that with metal salt (KI). A worm-like morphology is observed in the FE-SEM micrographs of $TiO_2$ nanoporous layer, due to the connection of $TiO_2$ nanoparticles resulting from adequate coating by electrolytes. DSSCs employing the supramolecular electrolytes with MPII and KI exhibit an energy conversion efficiency of 2.5 % and 0.5 %, respectively, at 100 $mW/cm^2$, indicating the importance of the cation of salt. Solar cell performances were further improved up to 3.7 % upon introduction of poly(ethylene glycol dimethyl ether) (PEGDME) with 500 g/mol.