• 대한기계학회논문집A
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• 제31권4호
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• pp.483-489
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• 2007

We have investigated quantitative measurement techniques of the degree of dispersion of single-walled carbon nanotubes (SWNTs). SWNTs were suspended in aqueous media using a sodium dodecyl sulfate (SDS) surfactant. SWNTs with different dispersion states were prepared by controlling the intensity and time of sonication and centrifugation. The laser spectroscopic techniques were employed to characterize the dispersion state; i.e., raman fluorescence and absorption spectroscopic techniques. Raman spectroscopy has been used to probe the dispersion and aggregation state of SWNTs in solution. Individually suspended SWNTs show increased fluorescence peaks and decreased roping peaks at a raman shift 267 $cm^{-1}$ compared with the samples containing bundles of SWNTs. The ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectrum of decanted supernatant samples show sharp van Hove singularity peaks

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.174-176
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• 2000

We have synthesized the new blue electroluminescent material, Bis(3-N-ethylcarbazolyl)cyanoisophthalidene(BECCIP), and characterized its properties by UV/visible absorption, photoluminescent(PL) and electroluminecent(EL) spectrum. This material is well vacuum-deposited far thin film and has clear surfaced thin film property. The BECCIP shows blue PL and EL spectra at around at 485nm.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.493-496
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• 1997

We have made disperse diazo black D(DB-D) ultrathin films using Langmur-Blodgett(LB) and vacuum-evaporation technique. Physical and electrical properties of the films were investigated. Solution was made with a concentration of 10$^{-3}$ mol/$\ell$ using chloroform. Moving wall apparatus (NL-LB140 S-MWC) was employed to make the LB films. X,Y and Z-type LB films were manufactured and studied by UV/visible absorbance spectra and morphology of surface using atomic force microscopy. Vacuum-evaporated DB-D think films were made at a pressure of 10$^{-5}$ torrr. The absorption peaks appear at 200 and 40nm in the LB films and vacuum-deposited films. And we have studied photoluminescence spectrum of the DB-D films. Also TGA and DSC properties of the DB-D have been observed and current -voltage characteristics of the DB-D LB films have been measured along the perpendicular direction.

• 미생물학회지
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• 제29권4호
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• pp.238-242
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• 1991

Extracellular laccase secreted from Pleurotus ostreatus was activated by $Cu^{2+}$ and $Cu^{+}$ . The enzyme was strongly inactivated by 8-hydroxyquinoline, potassium cyanide, sodium azide, sodium bisulfite and 2-mercaptoethanol. The two ionogenic groups, which have pKa values of 5.60-5.70 and 6.70-6.85 respectively, were found to relate with the active site of this enzyme. The oxidation reactions were brought about by initial single electron transfer process on the active site. The enzyme was found to be a metalloprotein which had about 3.9 cupric ions per molecule of protein as a prosthetic group. The enzyme showed a strong peak at 605 nm and a weak shoulder at 330 nm in UV-Visible absorption spectrum. Both signals disappeated upon treatment of the enzyme with 4 electron equivalent ascorbate. These results indicate that type I Cu peak and type III Cu shoulder are present in laccase.

• Bulletin of the Korean Chemical Society
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• 제15권2호
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• pp.145-150
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• 1994

The low temperature luminescence and excitation, room-temperature UV-visible and infrared spectra of [Cr(${\pm})chxn_3]Cl_3$ (chxn=trans-1,2-cyclohexanediamine) have been measured. It is found that the zero-phonon line in the excitation spectrum splits into two components by $47\;cm^{-1}$. The eight electronic transitions due to spin-allowed and spin-forbidden are assigned. As expected, nitrogen atoms of chxn ligand have strong ${\sigma}-donor $properties toward chromium(Ⅲ). The positions and splittings of sharp-line transitions are analyzed as a function of the Cartesian bite (${\alpha}$) and twist (${\beta}$) angles to predict the metal-ligand geometry.

• Bulletin of the Korean Chemical Society
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• 제20권4호
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• pp.451-455
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• 1999

The polymerization of 2-ethynylpyridine by alkyl bromide carrying carbazole moiety, 6-(N-carbazolyl)hexyl bromide, relatively proceed well to give the corresponding poly[6'-(N-carbazolyl)hexyl-2-ethynylpyridinium bromide) in high yields under DMF reflux conditions without any initiator or catalyst. This polymerization was influenced upon the initial monomer concentration. The polymer yields and inherent viscosities of the resulting polymers were in the range of 34-85% and 0.11-0.21 dL/g, respectively. Instrumental analyses using NMR, IR, and UV-visible spectroscopies and elemental analysis indicated that the resulting polymer has a conjugated polymer backbone system carrying pyridine and n-hexyl carbazole moiety. The polymers were mostly brown powders and completely soluble in DMF, DMSO, nitrobenzene, and formic acid. The photoluminescence spectrum of the dilute polymer solution with the excitation at 383 nm exhibited two sharp peaks at 495 and 540 nm.

• 공업화학
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• 제24권6호
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• pp.611-615
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• 2013

본 연구에서는 바나듐 산화물($VO_2$)과 텅스텐이 도핑된 바나듐 산화물(W-$VO_2$) 분말을 바나듐 산화물($V_2O_5$)과 옥살산수화물로부터 수열합성과 하소공정을 통하여 성공적으로 제조하였다. 시료들의 결정구조와 열변색 특성들은 FE-SEM, XRD, XPS, DSC 및 UV-Vis-NIR 분광기를 이용하여 분석하였다. W-$VO_2$ 시료에 W의 도핑량을 증가시키면, W-$VO_2$ 시료의 상전이 온도가 $70^{\circ}C$에서 $42^{\circ}C$로 낮아지는 경향이 있었다. 또한, W-$VO_2$ 시료를 상전이 온도 이상으로 가열시키면 UV-Vis-NIR 곡선이 가시광 영역에서는 변하지 않고 NIR 영역에서는 낮은 투과도 방향으로 이동하는 경향이 있었다.

• 한국결정성장학회지
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• 제19권1호
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• pp.15-18
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• 2009

본 연구에서는 근 자외선 및 가시광 영역에서 우수한 발광 강도를 가지는 적색 형광체를 얻기 위하여 고상 반응법으로 합성하여 $EU^{3+}$와 $Bi^{3+}$가 도핑 된 ${Y_2}{SiO_5}$의 발광 특성을 관찰하였다. 근자외선 영역인 ${\lambda}_{ex}=395nm$ 기준으로 측정하였고, $^5D_0-^7F_2$의 에너지 천이에 의해 612 nm 영역에서 강한 peak가 발생하였다. CST가 $Eu^{3+}-O^{2-}$에 의해 258 nm 영역 대에서 생성되었고, $Bi^{3+}$가 함께 도핑 된 것은 $Eu^{3+}-Bi^{3+}-O^{2-}$에 상호작용에 의해 282 nm 영역대의 장파장 쪽으로 이동하였다. $350\;nm{\sim}480\;nm$ 영역 대에 '$^7F_0{\to}^5L_9$ (364 nm), $^7F_0{\to}^5G_3$(381 nm), $^7F_0{\to}^5L_6$(395nm), $^7F_0{\to}^5D_3$(415 mn) and $^7F_0{\to}^5D_2$(466 nm)는 $Bi^{3+}$와 $EU^{3+}$ f-f 천이에 의해 발생하였다. $Bi^{3+}$의 도핑농도가 증가할수록 발광 강도가 증가함을 보이다가 0.125 mol 일 때 발광강도가 가장 우수하였고, $Bi^{3+}$의 도핑 농도가 0.125 mol 이상 되면 발광강도가 현저히 감소하는 것을 확인하였다.

• 대한화학회지
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• 제36권3호
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• pp.428-441
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• 1992

이핵성 다섯자리 Schiff base 착물계인 $Co(II)_2$ (BSPP)($H_2O)_2$, $Co(II)_2$ (BSPD)($H_2O)_2$, $Mn(II)_2$ (BSPP)($H_2O)_2$ 및 $Mn(II)_2$ (BSPD)($H_2O)_2$와 일핵성 다섯자리 Schiff base 착물계인 Co(II)(BSP)($H_2O)$ 및 Mn(II)(BSP)($H_2O)$들을 합성하였다. 이들 착물들의 조성을 원소분석, IR, UV-visible spectrum, T.G.A. 및 DSC 측정으로 알아보았다. 지지전해질용액 0.1M의 TEAP-Py (-DMSO 및 DMF)을 포함한 10mM 착물용액에서 유리질 탄소전극을 사용한 순환전압전류법과 DPP법으로 전기화학적 성질을 측정한 결과 이핵성 cobalt(II) 및 manganese(II) 착물들은 $M(III)_2$ / $Mn(II)_2$ 와 $Mn(II)_2$ / $M(I)_2$ (M; Co 및 Mn)의 두 과정에서 일전자의 환원과정이 각각 두 단계 환원과정에서 네 단계로 일어나지만 일핵성 착물들은 M(III) / M(II) 와 M(II) / M(I) 의 두 과정에서 각각 한 단계 산화${\cdot}$환원과정으로 일어남을 알았다.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1491-1504
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• 2012

InP quantum dot (QD)-organosilicon nanocomposites were synthesized and their photoluminescence quenching was mainly investigated because of their applicability to white LEDs (light emitting diodes). The as-synthesized InP QDs are capped with myristic acid (MA), which are incompatible with typical silicone encapsulants. We have introduced a new ligand, 3-aminopropyldimethylsilane (APDMS), which enables embedding the QDs into vinyl-functionalized silicones through direct chemical bonding. The exchange of ligand from MA to APDMS does not significantly affect the UV absorbance of the InP QDs, but quenches the PL to about 10% of its original value with the relative increase in surface related emission intensities, which is explained by stronger coordination of the APDMS ligands to the surface indium atoms. InP QD-organosilicon nanocomposites were synthesized by connecting the QDs using a short cross-linker such as 1,4-divinyltetramethylsilylethane (DVMSE) by the hydrosilylation reaction. The formation and changes in the optical properties of the InP QD-organosilicon nanocomposite were monitored by ultraviolet visible (UV-vis) absorbance and steady state photoluminescence (PL) spectroscopies. As the hydrosilylation reaction proceeds, the QD-organosilicon nanocomposite is formed and grows in size, causing an increase in the UV-vis absorbance due to the scattering effect. At the same time, the PL spectrum is red-shifted and, very interestingly, the PL is quenched gradually. Three PL quenching mechanisms are regarded as strong candidates for the PL quenching of the QD nanocomposites, namely the scattering effect, F$\ddot{o}$rster resonance energy transfer (FRET) and cross-linker tension preventing the QD's surface relaxation.