• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.36.2-36.2
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• 2009

Low dielectric materials have been great attention in the semiconductor industry to develop high performance interlayer dielectrics with low k for Cu interconnect technology. In our study, the dielectric properties of SiOC /SiO2 thin film derived from polyphenylcarbosilane were investigated as a potential interlayer dielectrics for Cu interconnect technology. Polyphenylcarbosilane was synthesized from thermal rearrangement of polymethylphenylsilane around $350^{\circ}C{\sim}430^{\circ}C$. Characterization of synthesized polyphenylcarbosilane was performed with 29Si, 13C, 1H NMR, FT-IR, TG, XRD, GPC and GC analysis. From FT-IR data, the band at 1035 cm-1 is very strong and assigned to CH2 bending vibration in Si-CH2-Si group, indicating the formation of the polyphenylcarbosilane. Number average of molecular weight (Mn) of the polyphenylcarbosilane synthesized at $400^{\circ}C$ for 6hwas 2, 500 and is easily soluble in organic solvent. SiOC/SiO2 thin film was fabricated on ton-type silicon wafer by spin coating using 30wt % polyphenylcarbosilane incyclohexane. Curing of the film was performed in the air up to $400^{\circ}C$ for 2h. The thickness of the film is ranged from $1{\mu}m$ to $1.7{\mu}m$. The dielectric constant was determined from the capacitance data obtained from metal/polyphenylcarbosilane/conductive Si MIM capacitors and show a dielectric constant as low as 2.5 without added porosity. The SiOC /SiO2 thin film derived from polyphenylcarbosilane shows promising application as an interlayer dielectrics for Cu interconnect technology.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.801-809
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• 2007

Fly ash and blast furnace slag are an industrial by-product that can be alkali-activated to yield adhesive and cementitious materials, whose production is less energy-intensive and emits less $CO_2$ than ordinary Portland cement manufacture. A laboratory investigation was carried out to evaluate the effect of alkali-activating conditions on compressive strength of fly ash/slag cement and the acid corrosion resistance of this cement. Two alkali activator solution, NaOH and waterglass + NaOH solutions, were used. Waterglass concentration was the factor that gave the highest compressive strength in all tests. The next significant factor was the NaOH concentration, followed by curing temperature. Acid corrosion resistance of FC(fly ash cement) and FSC(fly ash/slag cement), such as sulfuric$(H_2SO_4)$ and hydrochloric acid(HCl), was for better than Portland cement(PC).

• Journal of Korean Society of Environmental Engineers
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• v.28 no.6
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• pp.661-666
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• 2006

The compressive strength of a paste composed of a low-calcium Class F fly ash and alkaline activator solutions was investigated. These activator solutions, made with sodium hydroxide, water glass and water, have a very high $OH^-$ concentration. The composition of alkaline activator solution and temperature have been shown to notably influence the development of the compressive strength of the fly ash-cements paste. Compressive strength of 50 MPa could be achieved by curing of the fly ash at $60^{\circ}C$ for 48 hrs or $85^{\circ}C$ for 24 hrs. This study presented the optimum mixing ratio of Class F fly ash/sodium hydroxide/water glass as 25:8:2 in weight basis, and activator/fly ash as 0.6/1.0 for high strength paste.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.762-769
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• 2015

The titania ($TiO_2$) nanoparticles with a diameter 2?3 nm were synthesized by controlling hydrolysis of titanium tetraisopropoxide (TTIP) in acid solution. Organic-inorganic hybrid coating solutions were prepared by reacting the titania nanoparticles with 3-glycidoxypropyl trimethoxysilane (GPTMS) by the sol-gel method. The hard coating films with high refractive index were obtained by curing thermally at $120^{\circ}C$ after spin-coating the coating solutions on the polycarbonate (PC) sheets. The coating films showed high optical transparency of 90% in the visible range and exhibited a pencil hardness of 2H. Also, the refractive index at 633 nm wavelength of coating films enhanced from 1.502 to 1.584 as the weight content of titania nanoparticles in the coating solutions increased from 4% to 25%.

• Polymer(Korea)
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• v.24 no.2
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• pp.228-236
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• 2000

The preparation of organophilic clay from Na$^{+}$-MMT was achieved by intercalation of alkylammonium bromide. The dispersed organophilic clay in NMP was then added to the solution of polyamic acids (BPDA-PPD, BTDA-ODA/ MPD) in NMP. After curing at 30$0^{\circ}C$, thin films of the polyimide/clay nanocomposite were prepared. The results of X-ray diffraction (XRD) shelved that the d-spacings of dried polyamic acid (PAA)-clay complexes increased in proportion to the chain length of the onium ion and patterns of two kinds of PAA-clay complexes were similar. The d-spacings of approximately 13.2 $\AA$ for the polyimide/clay nanocomposites were independent of the initial onium ion chain length and the species of PAA. From the study of XRD and transmission electron microscopy (TEM), we found layered silicates were dispersed in polyimide matrix and the resultants were intercalated nanocomposites. TGA result showed thermal stability of polyimide nanocomposite improved a little more than the pure polyimide. From the result of dynamic mechanical property, we found that the storage modulus of the nanocomposites had increased by 1.2-1.8 times of the pure polyimides.s.

• Carbon letters
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• v.25
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• pp.1-13
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• 2018

Gold functionalized graphene oxide (GOAu) nanoparticles were reinforced in acrylonitrile-butadiene rubbers (NBR) via solution and melt mixing methods. The synthesized NBR-GOAu nanocomposites have shown significant improvements in their rate of curing, mechanical strength, thermal stability and electrical properties. The homogeneous dispersion of GOAu nanoparticles in NBR has been considered responsible for the enhanced thermal conductivity, thermal stability, and mechanical properties of NBR nanocomposites. In addition, the NBR-GOAu nanocomposites were able to show a decreasing trend in their dielectric constant (${\varepsilon}^{\prime}$) and electrical resistance on straining within a range of 10-70%. The decreasing trend in ${\varepsilon}^{\prime}$ is attributed to the decrease in electrode and interfacial polarization on straining the nanocomposites. The decreasing trend in electrical resistance in the nanocomposites is likely due to the attachment of Au nanoparticles to the surface of GO sheets which act as electrical interconnects. The Au nanoparticles have been proposed to function as ball rollers in-between GO nanosheets to improve their sliding on each other and to improve contacts with neighboring GO nanosheets, especially on straining the nanocomposites. The NBR-GOAu nanocomposites have exhibited piezoelectric gauge factor (${GF_{\varepsilon}}^{\prime}$) of ~0.5, and piezo-resistive gauge factor ($GF_R$) of ~0.9 which clearly indicated that GOAu reinforced NBR nanocomposites are potentially useful in fabrication of structural, high temperature responsive, and stretchable strain-sensitive sensors.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.574-584
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• 2003

The most common deterioration cause of concrete structures in urban environment is carbonation. Recently, the $CO_2$ concentration and temperature at atmosphere is sharply increased with time due to global warming phenomena. In this study, the climate scenario IS92a, which was suggested by the IPCC, is used to consider temperature and atmospheric $CO_2$ concentration change in the model of service life prediction. The modified mathematical solution, which was based on the Fick's 1st law of diffusion, was used to reflect concrete materials properties such as the degree of hydration of concrete with elapsed time, and important parameters, which associated with deterioration rate. The techniques of service life prediction are developed introducing the method of reliability and stochastic concept to consider microclimatic condition in Seoul, South Korea. From the result of service life prediction, concrete containing high W/C ratio is shown fast carbonation rate due to $CO_2$ concentration increase. It is concluded that the deterioration of concrete structures due to carbonation is insignificant problem on the conditions that below W/C 55%, well curing concrete.

• Korean Journal of Optics and Photonics
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• v.28 no.2
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• pp.53-58
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• 2017

This paper presents the design and fabrication of a planar nano-diffraction grating for an integrated miniature spectrometer module. The proposed planar nano-diffraction grating consists of nonuniform periods, to focus the reflected beams from the grating's surface, and an asymmetrical V-shaped groove profile, to provide uniform diffraction efficiency in the wavelength range from 400 to 650 nm. Also, to fabricate the nano-diffraction grating using low-cost UV-NIL technology, we analyzed the FT-IR spectrum of a uvcurable resin and optimized the conditions for the UV curing process. Then, we precisely fabricated the polymeric nano-diffraction grating within 5 nm in dimensional accuracy. The integrated spectrometer module using the fabricated polymeric planar nano-diffraction grating provides spectral resolution of 5 nm and spectral bandwidth of 250 nm. Our integrated spectrometer module using a polymeric planar nano-diffraction grating serves as a quick and easy solution for many spectrometric applications.

• Journal of the Korean Applied Science and Technology
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• v.29 no.1
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• pp.13-18
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• 2012

A die casting mold releasing agent was prepared from aqueous mixture of powdery carbon black and water soluble natural polymeric materials such as xanthan gum(X-gum) and carboxymethyl cellulose(CMC), which were used as thickening agent as well as curing agent with aldehydes. The suitable concentration of natural polymers for stable dispersion of carbon black in water was 0.25 wt% of X-gum or 1.0 wt% of CMC. When CMC was used less than 1 wt%, the final carbon black disperion showed a rapid phase separation. The adhesion of carbon black releasing agent on glass plate was improved with the amount of crosslinking agent, glutaraldehyde and chain extender, oligosaccharide. However, the affinity of carbon black releasing agent prepared with X-gum was stronger than that with CMC on glass plate. The final carbon black mold releasing agents prepared under our mixing conditions can be applied to the production of castings of high quality with good workability and without worthening evironmental situations.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.269-275
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• 2014

In this study, the adsorption efficiency of mixed heavy metals in aqueous solution was investigated using steel slag. Moreover, heavy-metal stabilization treatment of contaminated marine sediment was achieved using steel slag as stabilizing agents. Heavy metal adsorption was characterized using Freundlich and Langmuir equations. The equilibrium adsorption data were fitted well to the Langmuir model in steel slag. The adsorption uptake of heavy metals were higher in the order of $Pb^{2+}$ > $Cd^{2+}$ > $Cu^{2+}$ > $Zn^{2+}$ > $Ni^{2+}$. The steel slage was applied for a wet-curing duration of 150 days. From the sequential extraction results, the exchangeable, carbonate, and oxides fractions of Ni, Zn, Cu, Pb, and Cd in sediment decreased by 13.0%, 6.0%, 1.3%, 17.0%, and 50.0%, respectively.