• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2408-2412
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• 2013

We demonstrate herein the synthesis and modification of magnetic nanoparticles and its use in the immobilization of the lipase. Magnetic $Fe_3O_4$ nanoparticles (MNPs) were prepared by simple co-precipitation method in aqueous medium and then subsequently modified with tetraethyl orthosilicate (TEOS) and 3-aminopropyl triethylenesilane (APTES). Silanization magnetic nanoparticles (SMNP) and amino magnetic nanomicrosphere (AMNP) were synthesized successfully. The morphology, structure, magnetic property and chemical composition of the synthetic MNP and its derivatives were characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) analysis, X-ray diffraction, superconducting quantum interference device (SQUID) and thermogravimetric analyses (TGA). All of these three nanoparticles exhibited good crystallization performance, apparent superparamagnetism, and the saturation magnetization of MNP, SMNP, AMNP were 47.9 emu/g, 33.0 emu/g and 19.5 emu/g, respectively. The amino content was 5.66%. The AMNP was used to immobilize lipase, and the maximum adsorption capacity of the protein was 26.3 mg/g. The maximum maintained activity (88 percent) was achieved while the amount of immobilized lipase was 23.7 mg $g^{-1}$. Immobilization of enzyme on the magnetic nanoparticles can facilitate the isolation of reaction products from reaction mixture and thus lowers the cost of enzyme application.

• Journal of the Korean Chemical Society
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• v.21 no.1
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• pp.53-59
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• 1977

A method of synthesizing $NaAlCO_3(OH)_2$ (Dawsonite) and $KAlCO_3(OH)_2$, was investigated by blowing $CO_2$ gas into sodium and potassium aluminate solutions. The reactions were accomplished at a temperature of 80 to $90^{\circ}C$, while $CO_2$ gas was blowing into the solutions which the molar ratios of $Na_2O/Al_2O_3,\;and\;K_2O/Al_2O_3$ were 6 to 8 and 8 to 10, respectively. It was observed that highly purified Dawsonite and $KAlCO_3(OH)_2$ are produced when Alumina is present in Boehmite at an equilibrium solid phase with a large amount of $HCO_3^-$ in the solutions. The rational formulas of Dawsonite and $KAlCO_3(OH)_2$synthesized under the conditions should be expressed as $NaAlO(OH)HCO_3\;and\;KAlO(OH)HCO_3$, respectively, by IR analysis. In addition, electron microscopic observation also indicated that Dawsonite in a fibrous crystal and $KAlCO_3(OH)_2$ in a needleshaped crystal.

• Polymer(Korea)
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• v.33 no.6
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• pp.520-524
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• 2009

The effects of oxidative degradation on the performance of crosslinked polyethylene pipes were analyzed by the investigation of tensile properties and chemical structure change of the pipes during oxidative degradation. Annealing at high temperatures or UV irradiation method was used to induce the oxidative degradation of the crosslinked polyethylene pipes and the effects of the die temperature on the oxidative degradation of the pipes were also investigated. The tensile properties and chemical structure change of the pipes were investigated by universal testing machine and FT-IR, respectively. With the progress of thermo-oxidative degradation the tensile strength of the pipes slowly decreased but the elongation at break rapidly decreased, and the chemical structure of the pipes also changed considerably because of the introduced oxygen molecules. These results would be useful in estimating the performance deterioration of the crosslinked polyethylene pipes due to the oxidative degradation during production and storage.

• Journal of the Korean Vacuum Society
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• v.6 no.3
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• pp.213-219
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• 1997

The plasma polymerized styrene films were prepared by using an inter-electrode capacitively coupled gas-flow-type reactor, and the effects of plasma polymerization condition on the molecular weight distribution were investigated by Fourier Transform Infrared (FT-IR), Pyrolysis Gas Chromatography(PyGC), Differential Scanning Calorimetry(DSC) and Gel Permeation Chromatography(GPC). From the above results, the very cross-linked films different from chemical characteristics of the starting monomer were taken out, and it is realized that the molecular structure, cross linking density, and molecular weight distribution could be controlled by changing the parameters such as deposition pressure, deposition power and gas flow rate. Accordingly, it is suggested that plasma polymerization method performed by inter-electrode capacitively coupled gas-flow-type reactor has good characteristics for manufacturing the functional organic thin films which can be applied in sensors, opto-electric device, photo-resist by changing the polymerization parameters.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.8-16
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• 2010

This paper presents a new small target detection method using the cross product of the temporal pixels based on the temporal profile in infrared (IR) image sequences. The temporal characteristics of small targets and the various backgrounds are different. A new algorithm classifies target pixels and the background pixels through the hypothesis testing using the cross product of pixels on the temporal profile and predicts the temporal backgrounds based on the results. The small targets are detected by subtracting the predicted temporal background profile from the original temporal profile. For the performance comparison between the proposed algorithm and the conventional algorithms, the receiver operating characteristics (ROC) curves is computed in experiment. Experimental results show that the proposed algorithm has better discrimination and a lower false alarm rate than the conventional methods.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.103-107
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• 2000

Boron Phosphide films were deposited on the glass substrate at the low temperature, 55$0^{\circ}C$, by the reaction of B$_2$H$_{6}$ with PH$_3$ using CVD. $N_2$ was employed as carrier gas. The optimal gas rates were 50 $m\ell$/min for B$_2$H$_{6}$, 50 $m\ell$/min for PH$_3$ $m\ell$/min and 1.5 $\ell$/min for $N_2$. To investigate the annealing effect, the films were annealed for 1hour, 3hours in $N_2$ambient at 55$0^{\circ}C$ and tested. The deposition rate was 1000$\AA$/min and the refractive index of film was 2.6. The measurement of X-RD shows that the films have the preferred orientation of (1 0 1) and the intensity of the peak for (1 0 1) orientation decreases according to the annealing time. The data of VIS spectrophotometer proved that the films are transparent in the visible range and the maximal transmittance increases according to the annealing time; 75.49% for as-deposited, 76.71% for 1hr-annealed and 86.4 % for 3hrs-annealed. The measurement of AFM shows that the average surface roughness increases according to the annealing time; 73$\AA$ for as-deposited, 88.9$\AA$ for 1hr-annealed and 220$\AA$ for 3hrs-annealed. Also, The data of the secondary electron emission rate(Υ) shows that the secondary electron emission rate increases according to the annealing time; 0.317 for 1hr-deposited, 0.357 for 1hr-annealed and 0.537 for 3hrs-annealed. And, The measurement of FT-IR that the characteristic of transmittance in the infrared range was stabilized through annealing.ing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.4
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• pp.373-379
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• 2002

We investigated the evolution of magnetoresistance and magnetic property of tunneling magnetoresistive(TMR) device with microstructure and plasma oxidation time. TMR devices have potential applications for non volatile MRAM and high density HDD reading head. We prepared the tunnel magnetoresistance(TMR) devices of Ta($50{\AA}$)/NiFe($50{\AA}$)/IrMn($150{\AA}$)/CoFe($50{\AA}$)/Al($13{\AA}$)-O/CoFe($40{\AA}$)/FiFe($400{\AA}$)/Ta(($50{\AA}$) structure which have $100{\times}100\mu\textrm{m}^2$ junction area on $2.5{\times}2.5\textrm{cm}^2$ Si/$SiO_2$(($1000{\AA}$) substrates by an inductively coupled plasma(ICP) magnetron sputter. We fabricated the insulating layer using an ICP plasma oxidation method by with various oxidation time from 30 sec to 360 sec, and measured resistances and magnetoresistance(MR) ratios of TMR devices. We found that the oxidized sample for oxidation time of 80 sec showed the highest MR radio of 30.31 %, while the calculated value regarding inhomogeneous current effect indicated 25.18 %. We used transmission electron microscope(TEM) to investigate microstructural evolution of insulating layer. Comparing the cross-sectional TEM images at oxidation time of 150 sec and 360 sec, we found that the thickness and thickness variation of 360 sec-oxidized insulating layer became 30% and 40% larger than those of 150 sec-oxidized layer, repectively. Therefore, our results imply that increase of thickness variation with oxidation time may be one of the major treasons of the MR decrease.

• Journal of the Korean Ceramic Society
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• v.51 no.6
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• pp.544-548
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• 2014

Aluminum nitride was synthesized using a carbothermal method from mesoporous alumina having a high surface area (> $1,000m^2/g$) as an aluminum source and CNTs (carbon nano tubes) as a carbon source. In this case the mesoporous alumina was used as the starting material instead of ${\alpha}-Al_2O_3$ with the expectation that the mesopores in mesoporous alumina act as channels for N2 gas and elimination of CO generated as by-product. It is also expected that the synthetic temperature should be lower compared to the use of ${\alpha}-Al_2O_3$ as a starting material due to its high surface area. The crystallinity of the produced aluminum nitride was studied by XRD and FT-IR, and the microstructure was investigated by FE-SEM. Also the purity of the aluminum nitride was analyzed through N/O determinator and ICP analysis.

• Journal of Surface Science and Engineering
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• v.36 no.1
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• pp.14-21
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• 2003

Thin films of ZrO$_2$ and TiO$_2$ were deposited on Si(100) substrates using RF magnetron sputtering technique. To study an influence of the sputtering parameters, systematic experiments were carried out in this work. XRD data show that the $ZrO_2$ films were mainly grown in the [111] orientation at the annealing temperature between 800 and $1000^{\circ}C$ while the crystal growth direction was changed to be [012] at above $1000^{\circ}C$. FT-IR spectra show that the oxygen stretching peaks become strong due to $SiO_2$ layer formation between film layers and silicon surface after annealing, and proved that a diffusion caused by either oxygen atoms of $ZrO_2$ layers or air into the interface during annealing. Different crystal growth directions were observed with the various deposition parameters such as annealing temperature, RF power magnitude, and added $O_2$ amounts. The growth rate of $TiO_2$ thin films was increased with RF power magnitude up to 150 watt, and was then decreased due to a sputtering effect. The maximum growth rate observed at 150 watt was 1500 nm/hr. Highly oriented, crack-free, stoichiometric polycrystalline $TiO_2$<110> thin film with Rutile phase was obtained after annealing at $1000^{\circ}C$ for 1 hour.

• Journal of Conservation Science
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• v.28 no.4
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• pp.297-303
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• 2012

Samsebul, the altar portrait behind the statue of Buddha in the main building of Bonghwang temple in Andong, has been designated as Tangible Cultural Property No. 406. These alter portraits have significance as the standard of the research of Samsebul in Joseon period. In this study, fibre of the ground textile is identified using microscopic examination, solubility test, ATR-FT-IR, SEM, XRD. Two samples from Yaksabul(A, B), one sample from Seokgabul(C), and one sample from Amitabul(D), which were collected during the conservation process, were prepared for this study. In previous record, above samples were documented as hemp. Due to severe deterioration and accumulated dust layers on these samples, it was hard to recognize them with naked eyes, but through this study, we could identify that all samples except one from Yaksabul(A) are silk.