• Polymer(Korea)
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• v.34 no.2
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• pp.150-153
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• 2010

In this research, biomolecule-immobilized multi-walled carbon nanotubes (MWCNTs) were prepared by using radiation-induced graft polymerization. For the immobilization of biomolecules, the surface of MWNCTs was functionalized by radiation-induced graft polymerization of acrylic acid. Based on the results of TGA and Raman spectroscopy it was found that acrylic acid was effectively graft-polymerized on the MWCNTs. Biomolecules such as DNA and proteins were immobilized onto the resultant poly(acrylic acid)-grafted MWCNTs. The results of the X-ray photoelectron spectroscopy and fluorescence microscopy confirmed that the biomoelcules were successfully immobilized on the poly(acrylic acid)-grafted MWCNTs.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.865-868
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• 2011

An organic substance, hydroquinone is used to form clathrate compounds in order to identify separation characteristics of carbon dioxide in flue gas. Formed samples were analyzed by means of the solid-state $^{13}C$ nuclear magnetic resonance (NMR) and Raman spectroscopic methods to examine enclthration behaviors of guest species. In addition, elemnetal analysis was also performed in order to evaluate separation efficiency of $CO_2$ in a quantitative way. Based on the experimental results obtained, $CO_2$ molecules are found to be captured into the clathrate compound more readily than $N_2$ molecules. Moreover, because such preferential enclathration is even more significant at low pressure conditions, $CO_2$ separation/recovery from flue gas can be achieved with minimizing additional energy cost for the technique. Experimental results obtained in this study can provide useful information on separation techniques of flue gas or selective separation of gas mixtures in the future.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.253-257
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• 2017

Graphene is a monolayer carbon material which consists of $sp^2$ bonding between carbon atoms. Its excellent intrinsic properties allow graphene to be used in various research fields. Many researchers believe that graphene is suitable for electronic device materials due to its high electrical conductivity and carrier mobility. Through chemical doping, n- or p-type graphene can be obtained, and consequently graphene-based devices which have more comparable structure to common semiconductor-based devices can be fabricated. In our research, we introduced the dielectrophoresis process to the chemical doping step in order to improve the effect of chemical doping of graphene selectively. Under 10 kHz and $5V_{pp}$ (peak-to-peak voltage), doping was conducted and the Au nanoparticles were effectively formed, as well as aligned along the edges of graphene. Effects of the selective chemical doping on graphene were investigated through Raman spectroscopy and the change of its electrical properties were explored. We proposed the method to enhance the doping effect in local region of a graphene layer.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.106-110
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• 2023

Lignin is compatible with various polymeric materials and useful as a carbon precursor. In this work, carbon monolith films were produced from polyacrylonitrile (PAN)@lignin precursor films by a controlled carbonization cycle. In addition, their morphological features, electrical properties, and adsorption behavior were analyzed and compared with those of carbonized PAN films. The successful formation of PAN@lignin precursor was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. SEM was used to examine the morphology of precursor and carbonized films, revealing that both precursor and carbonized films retained structural stability following carbonization. A trace of lignin in the carbonized films was also found. The pore structure of the carbonized PAN@lignin film was measured using the BET method, indicating the formation of fairly uniform pores. The electrical properties were also analyzed to obtain the Ohmic relation, which demonstrated that the electrical signal was influenced by incoming materials. Finally, the carbonized PAN@lignin films were useful as adsorbents to remove metal ions. This study provides important information for future initiatives in relevant research fields.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.3
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• pp.124-131
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• 2016

Baseline correction is very important due to influence on performance of spectral analysis in application of spectroscopy. Baseline is often estimated by parameter selection using visual inspection on analyte spectrum. It is a highly subjective procedure and can be tedious work especially with a large number of data. For these reasons, it is an objective and automatic procedure is necessary to select optimal parameter value for baseline correction. Asymmetrically reweighted penalized least squares (arPLS) based on penalized least squares was proposed for baseline correction in our previous study. The method uses a new weighting scheme based on the generalized logistic function. In this study, we present an automatic selection of optimal parameter for baseline correction using arPLS. The method computes fitness and smoothness values of fitted baseline within available range of parameters and then selects optimal parameter when the sum of normalized fitness and smoothness gets minimum. According to the experimental results using simulated data with varying baselines, sloping, curved and doubly curved baseline, and real Raman spectra, we confirmed that the proposed method can be effectively applied to optimal parameter selection for baseline correction using arPLS.

• Journal of Adhesion and Interface
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• v.22 no.4
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• pp.136-143
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• 2021

Polyurea has been investigated as a polymer matrix for composite materials because of its high mechanical strength. Although polyurea has a similar chemical structure to polyurethane, it has much higher strength and durability. In this study, the fabrication of polyurea composites reinforced with carbon nanotube (CNT) and graphene oxide (GO) is demonstrated to enhance the tensile strength of the glass fibers composite. Using FTIR and Raman spectroscopies, the chemical structures of polyurea, CNT, and GO are investigated. As a result, spectroscopy analysis reveals that the chemical structure of CNT, GO, and polyurea is maintained during the fabrication of the composite structure. Scanning electron microscopy reveals the uniform distribution of CNT and GO across the polyurea matrix. The reinforcement of 1 wt% CNT in polyurea enhances the tensile strength of CNT/polyurea composites. In contrast, the reinforcement of GO in polyurea induces the degradation of the tensile strength of GO/polyurea composites.

• Composites Research
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• v.36 no.3
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• pp.167-172
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• 2023

The manufacturing technology of composite material is applicable with filler characteristics maintaining low cost, flexibility, and easy process to develope the various functional composite materials. To realize functional composites, various researches on the high performance of composite materials using graphene as a filler is being actively conducted. In this study, physical and chemical properties were investigated using graphene to improve high functional properties. Graphene oxide (GO) was prepared using graphane nanoplatelet (GNP), and reduced graphene oxide (R-GO) was formed by reducing GO. The physical properties of GO and R-GO were analyzed, and the reliability of the manufactured method was reviewed by comparing that of GNP results. As a result of analysis by Raman spectroscopy, in the case of R-GO, it was confirmed that the intensity of D-peak and G-peak decreased compared to GO, and an increase of 0.08 was observed through the ratio of ID/IG. For the FTIR results, GO and RGO has a repeating C-C and C=C connection structure unlike GNP. GO and R-GO show clear peaks for C-O bond, C=C bond, C=O bond, and O-H bonding. As a result of X-ray diffraction analysis, GNP showed a wide diffraction peak at 25.86° of (002) plane characteristics, whereas GO and R-GO showed peaks corresponding to (001) and (100) planes. It was also found that the interlayer distance of GO increased by about 2.6 times compared to GNP.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.197-206
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• 1997

A SiC epilayer on the 6H-SiC crystal substrate was grown by chemical vapor deposition (CVD). The crystal structure of the SiC epilayer was investigated by using the X-ray diffraction patterns and the Roman scattering spectroscopy. The SiC epilayer on the 6H-SiC substrate was grown to be homoepilayer by CVD. In order to distinguish a certain SiC polytype mixed in the SiC crystal grown by the modified Lely method, we have calculated the X-ray diffraction intensities and Brags angles of the typical SiC crystal powders. By comparing the measured X-ray diffraction pattern with the calculated ones, it was identified that the SiC crystal grown by the modified Lely method was the 6H-SiC crystal mixed some 15R-SiC.

• Composites Research
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• v.25 no.5
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• pp.159-163
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• 2012

The coating of metal surface with carbon nanotubes(CNTs) has been studied for the heat transfer enhancement of the boiling and condensation of refrigerant. The multiwalled carbon nanotube/copper oxide(CuO) composite powder, which has been surface modified by dispersant and polyvinyl alcohol solution, was ultrasonically sprayed and sintered on a copper wafer. In this paper, experiments were performed to assess the characterization and comparison of the carbon nanotube before and after sinterning and the morphology changes of the CNT/CuO-coated surface by using different dispersants. The dispersants used are THF (Tetrahydrofuran), SDBS(Dodecylbenzenesulfonic acid sodium salt), SDS(Sodium dodecy sulfate). The samples were examined by scanning electron microscopy(SEM), thermogravimetric analysis(TGA), differential scanning calorimeter(DSC) and Raman spectroscopy.

• Composites Research
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• v.26 no.6
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• pp.373-379
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• 2013

The coating of metal surface with carbon nanotubes (CNTs) has been studied for the heat transfer enhancement of the boiling and condensation of refrigerant. The MWCNT/copper composite powder was made by the attrition ball milling, which has been coated on the copper wafer by electrostatic powder coating and sintered with electric furnace. In this paper, experiments were performed to assess the characterization and comparison of CNT before and after sinterning and the morphology changes of the CNT/Cu-coated surface. The samples were examined by the scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDAX) and raman spectroscopy. To verify the heat transfer enhancement, boiling heat transfer tests were performed.