• 한국전기전자재료학회논문지
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• 제13권5호
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• pp.444-450
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• 2000

We prepared Co-Cr thin film for perpendicular magnetic recording media with facing targets sputtering system(FTS system) which can deposit a high quality thin film in plasma-free state and wide range of working pressure. The effect of sputtering conditions(argon gas pressure and substrate temperature) on the magnetic and the crystallographic characteristic of Co-Cr thin film was investigated. And the variation of perpendicular coercivity with the variation of film thickness was studied. As a result we obtained the high perpendicular coercivity of 1900Oe and the good dispersion angle of c-axis($\Delta$$\theta$$_{50}$) of 5$^{\circ}$on the film thickness of 100nm for the promising recording layer of perpendicular magnetic recording media.c recording media.a.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기물성,응용부문
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• pp.6-8
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• 2002

In order to prepare magnetic recording layer with a good quality crystallographic characteristic. We prepared $Co_{77}Cr_{20}Ta_3$ layer for perpendicular magnetic recording media on slide glass substrate by Two-Step Methode. The thickness of magnetic layer was fixed 100 nm and buffer layer were varied from 10 to 50 nm, and input current was varied from 0.2[A] to 0.5[A]. The surface morphology and crystal orientation of the CoCrTa films were examined with XRD. Prepared thin films showed improvement of dispersion angle of c-axis orientation ${\Delta}{\theta}_{50}$ caused by inserting buffer layer.

• 열처리공학회지
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• 제34권6호
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• pp.281-286
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• 2021

Arc ion plating (AIP), laser cladding, and nitriding are methods that can prevent mold damage or repair and create cracks and breakages on the die surface. The dissolution and soldering behavior of coated SKD61 by using arc ion plating, laser cladding, and nitriding was investigated. The structure of the coating was investigated as a function of deposition conditions by X-ray diffraction and the crystallographic orientation was determined using the texture factor. The TiAlN film deposited with AIP showed excellent corrosion resistance in the molten aluminum alloy at 680℃. In this paper, we have detailed the corrosion and mass loss phenomena associated with these steel-cast metal interactions.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.16-16
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• 2002

The presently commercialized lithium-ion batteries use layer structured LiCoO₂ cathodes. Because of the high cost and toxicity of cobalt, an intensive search for new cathode materials has been underway in recent years. Recently, a concept of a one-to-one solid state mixture of LiNO₂ and LiMnO₂, i.e., Li[Ni/sub 0.5/Mn/sub 0.5/]O₂, was adopted by Ohzuku and Makimura to overcome the disadvantage of LiNiO₂ and LiMnO₂. Li[Ni/sub 0.5/Mn/sub 0.5/]O₂ has the -NaFeO₂ structure, which is characteristic of the layered LiCoO₂ and LiNiO₂ structures and shows excellent cycleability with no indication of spinel formation during electrochemical cycling. Layered Li[Ni/sub x/Co/sub 1-2x/Mn/sub x/]O₂ (x = 0.5 and 0.475) materials with high homogeneity and crystallinity were synthesized using a mechanical alloying method. The Li[Ni/sub 0.475/Co/sub 0.05/Mn/sub 0.475/]O₂ electrode delivers a high discharge capacity of 187 mAh/g between 2.8 and 4.6 V at a high current density of 0.3 mA/㎠(30 mA/g) with excellent cycleability. The charge/discharge and differential capacity vs. voltage studies of the Li[Ni/sub x/Co/sub 1-2x/Mn/sub x/]O₂ (x = 0.5 and 0.475) materials showed only one redox peak up to 50 cycles, which indicates that structural phase transitions are not occurred during electrochemical cycling. The magnitude of the diffusion coefficients of lithium ions for Li[Ni/sub x/Co/sub 1-2x/Mn/sub x/]O₂(x = 0.5 and 0.475) are around 10/sup -9/ ㎠/s measured by the galvanostatic intermittent titration technique (GITT).

• 한국재료학회지
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• 제13권8호
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• pp.497-502
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• 2003

Crystallographic characteristics and interfacial structures of $Al_2$$O_3$and $ZrO_2$dielectric films prepared by atomic layer chemical vapor deposition (ALCVD) were investigated at atomic scale by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS)/electron energy-loss spectroscopy (EELS) coupled with a field-emission transmission electron microscope. The results obtained from cross-sectional and plan-view specimens showed that the $Al_2$$O_3$film was crystallized by annealing at a high temperature and its crystal system might be evaluated as either cubic or tetragonal phase. Whereas the $ZrO_2$film crystallized during deposition at a low temperature of ∼$300^{\circ}C$ was composed of both tetragonal and monoclinic phase. The interfacial thickness in both films was increased with the increased annealing temperature. Further, the interfacial structures of X$ZrO_2$$O_3$and $ZrO_2$films were discussed through analyses of EDS elemental maps and EELS spectra obtained from the annealed films, respectively.

• Toxicological Research
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• 제30권1호
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• pp.33-38
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• 2014

The human cytochrome P450 2J2 catalyzes an epoxygenase reaction to oxidize various fatty acids including arachidonic acid. In this study, three recombinant enzyme constructs of P450 2J2 were heterologously expressed in Escherichia coli and their P450 proteins were successfully purified using a $Ni^{2+}$-NTA affinity column. Deletion of 34 amino acid residues in N-terminus of P450 2J2 enzyme (2J2-D) produced the soluble enzyme located in the cytosolic fraction. The enzymatic analysis of this truncated protein indicated the typical spectral characteristics and functional properties of P450 2J2 enzyme. P450 2J2-D enzymes from soluble fraction catalyzed the oxidation reaction of terfenadine to the hydroxylated product. However, P450 2J2-D enzymes from membrane fraction did not support the P450 oxidation reaction although it displayed the characteristic CO-binding spectrum of P450. Our finding of these features in the N-terminal modified P450 2J2 enzyme could help understand the biological functions and the metabolic roles of P450 2J2 enzyme and make the crystallographic analysis of the P450 2J2 structure feasible for future studies.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.103-106
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• 2002

We prepared $Co_{77}Cr_{20}Ta_{3}$ thin film with Facing Targets Sputtering Apparatus. which can deposit a high quality thin film CoCrTa magnetic layer for Perpendicular magnetic recording media. In order to obtain Good Crystal orientation of CoCrTa thin films. We prepared Thin Films on slide glass substrate. The thickness of Buffer-layer were varied from 10 to 50 nm and Magnetic layer thickness fixed 100[nm]. input current was varied from 0.2[A] to 0.5[A]. Substrate temperature was varied from room temperature to ${250^{\circ}C}$ respectively. The crystal orientation of the CoCrTa film were examined with XRD. Introduce Buffer-layer thin films showed improvement of dispersion angle of c-axis orientation (${\Delta\theta}_{50}$).

• Macromolecular Research
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• 제11권1호
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• pp.14-18
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• 2003

Grafting of glycidyl methacrylate (GMA) upon coralline hydroxyapatite in conjugation with demineralized bone matrix (CHA-DBM) using equal molar ratio of potassium persulfate/sodium metabisulfite redox initiating system was investigated in aqueous medium. The optimum reaction condition was standardized by varying the concentrations of backbone, monomer, initiator, temperature and time. The results obtained imply that the percent grafting was found to increase initially and then decrease in most of the cases. The optimum temperature and time were found to be 50 $^{\circ}C$ and 180 min, respectively, to obtain higher grafting yield. Fourier transform infrared (FT-IR) spectroscopy and X-ray powder diffraction (XRD) method were employed for the proof of grafting. The FT-IR spectrum of grafted CHA-DBM showed epoxy groups at 905 and 853 $cm^{-1}$ / and ester carbonyl group at 1731 $cm^{-1}$ / of poly(glycidyl methacrylate) (PGMA) in addition to the characteristic absorptions of CHA-DBM, which provides evidence of the grafting. The XRD results clearly indicated that the crystallographic structure of the grafted CHA-DBM has not changed due to the grafting reaction. Further, no phase transformation was detected by the XRD analysis, which suggests that the PGMA is grafted only on the surface of CHA-DBM backbone. The grafted CHA-DBM will have better functionality because of their surface modification and hence they may be more useful in coupling of therapeutic agents through epoxy groups apart from being used as osteogenic material.

• 한국재료학회지
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• 제33권7호
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• pp.279-284
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• 2023

One-dimensional MgO nanostructures with various morphologies were synthesized by a thermal evaporation method. The synthesis process was carried out in air at atmospheric pressure, which made the process very simple. A mixed powder of magnesium and active carbon was used as the source powder. The morphologies of the MgO nanostructures were changed by varying the growth temperature. When the growth temperature was 700 ℃, untapered nanowires with smooth surfaces were grown. As the temperature increased to 850 ℃, 1,000 ℃ and 1,100 ℃, tapered nanobelts, tapered nanowires and then knotted nanowires were sequentially observed. X-ray diffraction analysis revealed that the MgO nanostructures had a cubic crystallographic structure. Energy dispersive X-ray analysis showed that the nanostructures were composed of Mg and O elements, indicating high purity MgO nanostructures. Fourier transform infrared spectra peaks showed the characteristic absorption of MgO. No catalyst particles were observed at the tips of the one-dimensional nanostructures, which suggested that the one-dimensional nanostructures were grown in a vapor-solid growth mechanism.

• 한국미생물·생명공학회지
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• 제34권2호
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• pp.129-135
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• 2006

Zebrafish (Danio rerio)의 microsomal epoxide hydrolase(mEH)로 추정되는 유전자를 클로닝하고 그 특성을 연구하였다. D. rerio의 mEH 추정단백질은 포유동물의 mEH 및 세균의 EH들과 아미노산서열 상동성을 보였으므로 결정분자구조(1qo7 및 1ehy)를 template로 하여 homology modelling을 행하였다. 클로된 단백질은 $Asp^{233}$, $Glu^{413}$ 및 $His^{440}$으로 구성된 catalytic triad와 2개의 tyrosine 잔기 및 oxyanion hole이 보존되어 있었다. 생물정보학적인 분석 및 EH 활성시험은 추정단백질이 D. rerio의 mEH라는 것을 보여주었다. Racemic styrene oxide를 기질로 하여 활성시험을 행한 결과, 재조합 D. rerio mEH는 (R)-styrene oxide을 입체선택적으로 가수분해하였으며 45분 반응시간에 99%ee의 광학순도를 가진 (S)-styrene oxide를 33.5% 얻을 수 있었다.