• Bulletin of the Korean Chemical Society
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• 제7권5호
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• pp.334-337
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• 1986

The preparation of the metal-metal bonded complex $Cp_2ZrClFeCp(CO)_2$ has been achieved by the reaction of $Cp_2ZrCl_2$ and strong nucleophile $NaFeCp(CO)_2$. The more soluble metal-metal bonded complexes $Cp_2ZrRFeCp(CO)_2(R=CH_3,\;n-C_8H_{17}$) have also been prepared through the reaction of Cp$_{2}$ZrRCl and NaCpFe(CO)$_{2}$. The complexes were characterized by IR, Raman, $^{1}$H NMR and Mass spectra. The complete absorption (100-3800 cm$^{-1}$) spectra for the three metal-metal bonded molecules are reported and the bands of each vibration were assigned.

• Bulletin of the Korean Chemical Society
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• 제8권2호
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• pp.105-110
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• 1987

A theory in which the Enskog hard sphere collisional dynamics complements the hydrodynamic theory is applied to the fast modulation dephasing dynamics in liquids which leads to homogeneous line broadening in the isotropic Raman spectra. The dephasing times of several molecules in pure liquids and in trace solutions in the solvent $CCl_4$ are calculated and these are compared with experimental values. The temperature dependence of the dephasing time of liquid acetonitrile and the isothermal density dependence of the dephasing time of liquid methyl iodide are also investigated.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.625-629
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• 2011

A quantitative analysis of the decreasing rate of the monomer and increasing rate of the polymerization was made by monitoring radiation level increments using Raman spectroscopy within the therapeutic radiation range for a normoxic polymethacrylic acid gel dosimeter. The gel dosimeter was synthesized by stirring materials such as gelatin, distilled water, methacrylic acid, hydroquinone and tetrakis phosphonium chloride at $50^{\circ}C$, and the synthesized gel was contained in a 10- mm diameter and 32-mm high vial to conduct measurement. 24 hours after gel synthesis, it was irradiated from 0 Gy to 20 Gy by 2 Gy using a Co-60 radiotherapy unit. With use of the Cryo FE-SEM, structural changes in the 0 Gy and 10 Gy gel dosimeters were investigated. The Raman spectra were acquired using 532-nm laser as the excitation source. In accordance with fitting the changes in C-COOH stretching (801 $cm^{-1}$), C=C stretching (1639 $cm^{-1}$) and vinyl $CH_2$ stretching (3114 $cm^{-1}$) vibrational modes for monomer and $CH_2$ bending vibrational mode (1451 $cm^{-1}$) for polymer, sensitive parameter S for each mode was calculated. The values of S for monomer bands and polymer band were ranged in $6.0{\pm}2.6$ Gy and $7.2{\pm}2.3$ Gy, respectively, which shows a relatively good conformity of the decreasing rate of monomer and the increasing rate of polymerization within the range of error.

• 한국세라믹학회지
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• 제31권1호
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• pp.104-114
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• 1994

ZrO2 fibers were fabricated by means of the Sol-Gel process using Zr(O-nC3H7)4-H2O-C2H5OH-HNO3 solution as a starting material. The optimum experimental parameters such as molar ratio of starting materials, concentration, temperature, viscosity, the amounts of stabilizer and the pH of solution were determined. The experimentally determined optimum variables which produce good ZrO2 fibers were used to manufacture the Y2O3-and CaO-ZrO2 fibers. The amounts of Y2O3 and CaO were varied within the range from 1.5~5 mol% and 3~15 mol% respectively. The phase transformation and microstructural evolution of the fabricated ZrO2 gel fibers were investigated after heat treatments up to 120$0^{\circ}C$ by X-ray diffraction, Raman microprobe spectroscopy, SEM, and specific surface area and pore volume measurements. From the analysis of X-ray diffraction and Raman spectra, the phase of heat treated Y2O3-and CaO partially stabilized ZrO2 gel fibers(Y2O3:2.5~3 mol%, CaO:6~9 mol%) were identified as a tetragonal phase up to 100$0^{\circ}C$. The maximum tensile strength of 2.5Y2O3-97.5ZrO2 and 6CaO-94ZrO2 (in mol%) fibers heat treated at 100$0^{\circ}C$ for 1 hr was found be 1.3~2 GPa with diameters of 10~20 ${\mu}{\textrm}{m}$.

• 분석과학
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• 제11권1호
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• pp.8-12
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• 1998

2,2'-Biimidazole은 glycol과 ammonium 용액을 반응하여 합성하였다. 2,2'-biimidazole의 정확한 화학적 구조는 trans ($C_{2h}$) 또는 cis ($C_{2v}$)형 중 하나로 발표되었다. 본 실험은 2,2'-biimidazole의 화학 구조를 규명하기 위하여 FTIR과 Raman Spectrum의 서로 상호보완작용을 이용하여 분석하였으며, 그 외 $^1H$, $^{13}C$ NMR, computer molecular modeling도 사용하였다. 2,2'-biimidazole의 구조는 FTIR과 Raman 스펙트럼을 비교 분석한 결과 cis ($C_{2v}$) 보다는 trans ($C_{2h}$)로 판명되었다. 이 결과는 computer molecular modeling과 X-ray crystallography의 실험 결과와 일치한다. 본 연구는 pyridine nitrogen을 함유한 chelating 성질을 지닌 2,2'-biimidazole의 구조 규명에 좋은 증거로 사료된다.

• 한국전기전자재료학회논문지
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• 제20권7호
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• pp.606-610
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• 2007

This paper describes the Raman scattering characteristics of polycrystalline (poly) 3C-SiC thin films, in which they were deposited on the oxidized Si substrate by APCVD method according to growth temperature. Since the phonon modes were not measured for $0.4{\mu}m$ thick 3C-SiC, $2.0{\mu}m$ thick 3C-SiC deposited on the oxidized Si at $1180^{\circ}C$, in which TO (transverse optical mode) and LO (longitudinal optical mode) phonon modes were appeared at 794.4 and $965.7cm^{-1}$, respectively. The broad FWHM (full width half maximum) can explain that the crystallinity of 3C-SiC deposited at $1180^{\circ}C$ becomes polycrystalline instead of disorder crystal. Additionally, the ratio of intensity $I_{LO}/I_{TO}{\approx}1.0$ of 3C-SiC indicates that the crystal disorder of $3C-SiC/SiO_2/Si$ is small. Compared poly $3C-SiC/SiO_2$ with $SiO_2/Si$ interfaces, $1122.6cm^{-1}$ phonon mode was measured which may belong to C-O bonding and two phonon modes, 1355.8 and $1596.8cm^{-1}$ related to D and G bands of C-C bonding in the Raman range of 200 to $2000cm^{-1}$.

• 보존과학회지
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• 제38권2호
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• pp.117-123
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• 2022

본 연구는 한국의 고대 유리에서 납바륨유리 3점, 납유리 3점, 포타쉬유리 10점 그리고 소다유리 10점을 중심으로 라만분광분석법을 이용하여 고대 유리의 융제 분류와 납유리에서 납의 정량 분석에 대한 가능성을 분석하였다. 분석 결과, 신축 진동 영역에서 납바륨유리가 1040 cm^-1, 납유리가 1000 cm^-1으로 라만 피크 에너지의 차이를 보이며 포타쉬유리와 소다유리는 굽힘 진동 영역에서 Na과 K 양이온의 차이에 따라 포타쉬유리는 490 cm^-1에서, 소다유리는 560 cm^-1에서 라만 피크의 차이를 보인다. 이외에 납유리는 PbO 함량에 따라 라만 스펙트럼의 적색 편이가 비례하므로 이를 통하여 납유리의 주성분인 PbO의 함량을 정량적으로 분석할 수 있다. 즉, 라만분광분석법으로 납바륨, 납, 포타쉬 그리고 소다유리에 대한 분류와 납유리에서 PbO 함량을 측정할 수 있는 가능성이 확인된다.

• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2512-2518
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• 2014

The praseodymium-doped $TiO_2$ photocatalyst samples, which could degrade methyl orange under UV irradiation, were prepared by sol-microwave method for improving the photocatalytic activity of $TiO_2$. The resulting materials were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectra, Fourier transform infrared spectra (FTIR) and Ultraviolet-visible diffuse reflectance spectra (UV-vis DRS). It was found Pr doping retarded the growth of crystalline size and the phase transformation from anatase to rutile, and narrowed the band gap energy. Praseodymium doping brought about remarkable improvement in the photoactivity. The optimal dopant amount of Pr was 2% by molar of cement and the calcination temperature was $500^{\circ}C$ for the best photocatalytic activity. The improvement of photocatalytic activity was ascribed to the occurrence of lattice distortion and the effective containment of the recombination of the electron-hole by $Pr^{3+}$.

• Bulletin of the Korean Chemical Society
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• 제27권3호
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• pp.368-372
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• 2006

The cobalt titanate, $CoTiO_3$ nanoparticles have been prepared by calcinations of precursor obtained from a mixture of $TiO_2$ and $Co(OH)_2$ in aqueous cetyltrimethylammonium bromide (CTAB) solution. The nanoparticles were investigated with X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric/differential thermal analysis (TGA/DTA) to determine the crystallite size and the phase composition. The spectroscopic characterizations of these nanoparticles were also done with UV-Vis spectroscopy and FT-Raman spectroscopy. XRD patterns show that $CoTiO_3$ phase was formed at calcinations temperature above 600 ${^{\circ}C}$. UV-Vis absorption spectra indicate that the $CoTiO_3$ nanoparticles have significant red shift to the visible region (400-700 nm) with $\lambda_{max}$ = 500 nm compared to pure $TiO_2$ powder ($\lambda_{max}$ = 320 nm). The new absorption peaks (absorption at 696, 604, 520, 478,456, 383, 336, 267, 238, 208 $c m ^{-1}$), which were not appeared in FT-Raman spectra of P-25, also confirm the formation of Ti-O-Co bonds at above 600 ${^{\circ}C}$ and just not the mixtures of titanium dioxide with cobalt oxides.

• 대한기계학회논문집A
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• 제26권2호
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• pp.260-266
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• 2002

DLC films were deposited on Si wafer by RF plasma assisted CVD using CH4 gas. Tribological tests were conducted using rotating type ball on disk friction tester in dry air. Four kinds of mating balls were used. The mating balls were made with stainless steel but apply different annealing conditions to achieve different hardness conditions. Testing results in all load conditions showed that the harder the mating materials, the lower the friction coefficient among the three kind of martensite mating balls. In case of austenite balls, the friction coefficients were lower than fully annealed martensite ball. The high friction coefficient in soft martensite balls seems to be caused by the larger contact area between DLC film and ball. The wear tracks of DLC films and mating balls could have proven that effect. Measuring the wear track of both DLC films and mating balls have similar tendency comparing to the results of friction coefficients. Wear rate of austenite balls were also smaller than that of fully annealed martensite ball. The results of effect of applying load showed, the friction coefficients were become decrease when the applying loads exceed critical load conditions. The wear track of mating balls showed that some material transfer occurs from DLC film to mating ball during the high friction process. Raman spectra analysis showed that transferred material was a kind of graphite and contact surface of DLC film seems to undergo phase transition from carbon to graphite during the high friction process.