• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.824-829
• /
• 2007

Mechanical and thermal analysis properties of carbon fiber/epoxy composite for train carbody were evaluated by varying with environmental factors such as ultraviolet, temperature, and moisture. Accelerated environmental aging tester was utilized for this study. Testing temperature was set to $80^{\circ}C$ and ultraviolet was obtained through xenon-arc lamp. To consider moisture, water sprayed on specimen for 18 minutes every 2 hour. All the specimens were made of CF1263/Epoxy composite. Mechanical properties such as tensile, bending, and shear properties were evaluated through a material testing system. Also, thermal analysis properties such as storage shear modulus, loss shear modulus, and tan ${\delta}$ were measured through dynamic mechanical analyzer. Finally surfaces of the composite exposed to environmental factors were examined using a scanning electron microscope. From experimental results, those properties of CF1263/Epoxy composite were shown to be slightly decreased due to environmental factors.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.365.2-365.2
• /
• 2014

Nickel sulfide (NiS) has been utilized in optoelectronic applications, such as transformation-toughening agent for materials used in semiconductor applications, catalysts, and cathodic materials in rechargeable lithium batteries. Recently, high quality nickel sulfide thin films have been explored using ALD/CVD technique. Suitable precursors are needed to deposit thin films of inorganic materials. However, nickel sulfide precursors available for ALD/CVD process are very limited to nickel complexes with dithiocarbamate and alkanethiolate ligands. Therefore, it is essential to prepare novel nickel sulfide suitable for ALD/CVD precesses. Herein we report on the synthesis and characterization of new nickel sulfide complex with designed aminothiolate ligand. Furthermore thin films of NiS have been prepared on silicon oxide substrates by spin coating nickel precursor 10 wt% in THF. The novel complex has been characterized by means of 1H-NMR, elemental analysis, thermogravimetric analysis (TGA), X-ray Diffraction (XRD) and scanning electron microscope (SEM).

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1452-1454
• /
• 2002

Large turbine generator(rated 22kV) has failed in the stator winding area during normal operation. The capacitance and tan${\delta}$ were measured by Schering bridge in the zone 1, 2 and zone 3-6 stator windings. The capacitance and tan${\delta}$ in the zone 1, 2 of stator winding were higher than those of zone 3-6 in the stator winding. Experiments on microstructure property were conducted in the zone 1, 2 and zone 3-6 insulations, which were drawn out from stator windings of the large turbine generator. Microstructure analysis was characterized using scanning electron microscope(SEM). SEM results indicated that several isolated delaminations occurred at the interface of mica/epoxy insulations. Both thermal and mechanical aging cause the delamination.

• Polymer(Korea)
• /
• v.37 no.2
• /
• pp.196-203
• /
• 2013

Surface modification of meta-aramid fibers was performed by phosphoric acid treatment. Surface morphology and element composition of untreated and treated fibers were analyzed by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Effects of surface modification on the mechanical strength of aramid papers made from meta-aramid fibers and fibrid were investigated. Surface modification conditions were optimized by response surface analysis (RSA). Results show that phosphoric acid treatment increases the surface roughness and oxygen content of aramid fibers. They improve the interface bonding strength between aramid fibers and fibrid, which improves the tensile strength of aramid papers. The results of response surface analysis indicate that the tensile strength of aramid papers increases by 47.5% and reaches the maximum when meta-aramid fibers are treated with 21.1wt% phosphoric acid solution at $39.3^{\circ}C$ for 36.7 min.

• Journal of the Korean Society of Safety
• /
• v.14 no.1
• /
• pp.49-54
• /
• 1999

In this paper. we studied cut off characteristics and fire hazard of residual current protective devices(RCD or ELB) for low voltage. The operative time of RCD with grounding resistance was analyzed by using RCD operating tester. The surface structure and composition of insulator were analyzed by using scanning electron microscope(SEM) and energy dispersive x-ray spectroscopy(EDX). The surface of phenol resin showed network structure and void. The spectra shown in EDX analysis are composed not only of the corresponding elements but also of several new spectra, as CK. OK$\alpha$. MgK, SiK. and CaK, which were absent in original material.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.11
• /
• pp.2680-2686
• /
• 2009

The synthesis of a novel superabsorbent hydrogel with natural hybrid backbone via graft copolymerization of acrylamide (AAm) onto kappa-carrageenan (kC, as a polysaccharide) and gelatin (as a protein) under classic thermal conditions is described. The Taguchi method as a strong experimental design tool was used for synthesis optimization. A series of hydrogels were synthesized by proposed conditions of Qualitek-4 Software. Considering the results of 9 trials according to analysis of variance (ANOVA), optimum conditions were proposed. The swelling behavior of optimum hydrogel was measured in various solutions with pH values ranging from 1 to 13. In addition, swelling kinetics, swelling in various organic solvents, various salt solutions and On–Off switching behavior were investigated. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FTIR) and thermogravimetrical analysis (TGA). Surface morphology of the synthesized hydrogels was assessed by scanning electron microscope (SEM).

• Bulletin of the Korean Chemical Society
• /
• v.34 no.1
• /
• pp.149-153
• /
• 2013

The chemical functionalization of carboxylated multi-walled carbon nanotubes (MWCNT-COOH) by creatinine (MWCNT-Amide) and latter modification with 2-aminobenzophenone for producing 1-methyl-9-phenyl-1H-imidazo[4,5-b]quinolin-2-amine (MWCNT-quino) have been investigated. All products were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscope, elemental analysis, thermogravimetric analysis, derivative thermogravimetric and cellular investigations. The interesting point is that MWCNT-quino can be homogeneously dispersed in dimethylformamide and to some extent in ethyl alcohol without sonication. Also, MTT assay was used to examine the behavior of cell proliferation after 48 h of cell culture experiments. Cellular results showed high toxicity of MWCNT-quino on the cancer cells. These functionalizations have been chosen due to active sites of carbonyl and methylene groups in MWCNT-Amide and the creating quinoline derivative on the MWCNTs for future application.

• Journal of the Korean Society of Safety
• /
• v.29 no.4
• /
• pp.61-72
• /
• 2014

The aim of this study is to define the condition of optimal pre-treatment for preferable activated carbon fibers (ACFs), which are based on rayon fibers. This paper shows the ideal path of ACFs preparation process; implies that rayon fibers are pre-treated by various solvents with different times before the heating process. The pre-treated rayon fibers finally turned into desirable rayon fiber-based ACFs through optimal pre-treatment condition by heating processes. The thermal analysis method of pre-treated rayon fibers by thermo-gravimetry analyser (TGA) is an idealized tool, which analyzes the best thermal condition of pre-treatment process. Surface morphologies of resulting rayon fibers based ACFs were examined by scanning electron microscope(SEM). The results of TGA and SEM analyses show that the optimal pre-treatment condition for preparing ACFs was clearly defined, in terms of thermal stability and surface morphology.

• Journal of Institute of Convergence Technology
• /
• v.3 no.2
• /
• pp.39-43
• /
• 2013

Titanium has been used to satisfy various applications such as bio engineering, aerospace, electronics, automobile. Recently, micro fabrication technologies of metals such as titanium have been required to satisfy many conditions in various fields. To satisfy these demands, micro electrochemical process using laser marking can be an alternative method because it is one of the precision machining and efficient process. Micro electrochemical process using laser marking needs to accomplish form of the oxidized recast layer on metal surface by laser marking. The laser beam marking conditions such as average power, pulse repetition rate and marking speed should be properly selected to form oxidized recast layer. So, the characteristics of titanium surface according to laser marking conditions was investigated through SEM(scanning electron microscope), EDS(energy dispersive spectrometer) and surface roughness analysis.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05b
• /
• pp.159-164
• /
• 1997

Pyrolytic carbon layer was coated on A1203 balls by fluidized bed type chemical vapour deposition unit to develop the coating technology for the preparation of coated nuclear fuel. The deposition was carried out at the temperature ranges between 110$0^{\circ}C$ and 130$0^{\circ}C$ with various gas contents and flow rates. Source and carrier gas were propane and argon, respectively. X-ray analysis shows that the deposition layer was typical carbon spectra. The growth rate of carbon layer depended on the amount of source gas and the deposition temperature. For the alumina balls with 2mm in diameter, the deposition rate was 11${\mu}{\textrm}{m}$/hr in the flow gases containing 30% source gas at 130$0^{\circ}C$ with a total flow rate of 2.0$\ell$/min. Microstructural observation of the deposits with scanning electron microscope revealed that the deposits had relatively dense and isotropic structure. Chemical analysis by energy dispersive spectroscopy showed that the layer was pure carbon.