• 한국염색가공학회지
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• 제8권3호
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• pp.16-23
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• 1996

In order to know the change of weight loss, crystallinity, crystallite size(010) plane, and thermal properties of PET films which had before drawn and annealed at various temperature. It were treated in sodium triethylene glycolate-triethylene glycol(STEG-TEG) were prepared. The following results were abtain. The weight loss of PET films were increasing with increaing treated time in STEG-TEG solution and It showed a linear rlationship to the treated time. The crystallinity and crystallite size(010) plane of PET films decreased with increasing decomposition ratio when PET films were treated with before annealed under 16$0^{\circ}C$. The crystalline region on the surface of samples were decompose to thermal unstable crystalline structure

• Journal of Magnetics
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• 제18권1호
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• pp.1-4
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• 2013

Structural and magnetic properties of $Fe_{50}Mn_{50}$ nanocrystalline alloys prepared by the mechanical alloying technique (using commercial Fe and Mn powders as the precursors) are studied as a function of milling time, 1 hr to 48 hrs. The nano-crystallite size and shape are examined by using scanning electron microscopy (SEM). The effect of milling time on structural characterization was investigated using X-ray diffractometer (XRD) and extended X-ray absorption fine structure spectroscopy (EXAFS). Both XRD and EXAFS studies showed that the alloying process should be completed after 36 hrs milling. Concerning the magnetic behavior, the data obtained from superconducting quantum interference devices (SQUID) exhibited both magnetic saturation ($M_s$) and coercivity ($H_c$) depend strongly on the milling time, which are related to the changes in the crystallite size and magnetic dilution.

• 한국광물학회지
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• 제21권2호
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• pp.201-208
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• 2008

최근 기능성 나노물질로서 반도체 공정 중 기계.화학적 평탄화(CMP)용 연마제로 중요하게 사용되는 세리아(Ceria, $CeO_2$)에 대해서 X-선 회절분석을 실시하여 리트벨트법에 의한 상세한 구조해석 및 세리아의 입자크기와 미세응력을 측정하였다. 두 시료(RT735. RT835)의 리트벨트 계산 결과 R지수 값은 각각 $R_p(%)=8.50$, 8.34; $R_{wp}(%)=13.4$, 13.5; $R_{exp}(%)=11.3$, 11.5; $R_B(%)=2.21$, 2.36; S(GofF: Goodness of fit)=1.2, 1.2를 보여주며 계산이 잘 이루어졌음을 알 수 있다. $CeO_2$는 공간군 Fm3m을 가지며, 격자상수는 a=5.41074(2), 5.41130(6) ${\AA}$, V=158.406(1), 158.455(3) ${\AA}^3$으로 각각 계산되었다. 입자크기 및 미세응력 계산 결과, RT735의 평균 입자크기와 최대 응력은 37.42(1) nm, 0.0026이며, RT835는 72.80(2) nm, 0.0013으로 각각 결정되었다. 입자크기와 미세응력은 서로 반비례함을 알 수 있다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 춘계공동학술발표회요약집
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• pp.251-251
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• 2002

• 한국분말재료학회지
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• 제16권3호
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• pp.203-208
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• 2009

$Y_2O_3$:Eu red phosphor was prepared by microwave synthesis. The crystal phase, particle morphology, and luminescent properties were characterized by XRD, SEM, and spectrofluorometer, respectively. The prepared $Y_2O_3$:Eu particles had good crystallinity and strong red emission under ultravioletet excitation. The crystallite size increased with calcination temperature and satuarated at $1200^{\circ}C$. The primary particle size initially formed was varied from 30 to 450 nm with microwave-irradiation (MI) time. It was found that the emission intensity of $Y_2O_3$:Eu phosphor strongly depends on the MI time. In terms of the emission intensity, it was recommended that the MI time should be less than 15 min. The emission intensity of $Y_2O_3$:Eu phosphor prepared by microwave syntehsis strongly depended on the crystallite size of which an optimal size range was 50-60 nm.

• 한국표면공학회지
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• 제40권1호
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• pp.11-15
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• 2007

Stable metallic Cu/Zn nanoparticles were prepared in the base oil phase by hydrothermal method. The physical properties, such as crystal structure, crystallite size and crystallinity according to synthesis conditions have been investigated by XRD, FT-IR and TEM. In addition, 4-ball test has been performed in order to investigate the frictional wear properties of prepared nanosized Cu/Zn particles. The peaks of the X-ray diffraction pattern indicate that the particle size was very small and crystallinity of Cu/Zn particles was good. The micrographs of TEM showed that nanosized Cu/Zn particles possessed a spherical morphology with a narrow size distribution. The crystallite size of the Cu/Zn particles synthesized in base oils was 23-30 nm. It was found that the antiwear capacity increases with increasing Cu/Zn concentration. When the concentration of Cu/Zn was 5.0 wt%, the wear scar diameters was 0.38 mm.

• Transactions on Electrical and Electronic Materials
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• 제12권4호
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• pp.164-168
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• 2011

Nanocrystalline cadmium sulphide (CdS) thin films were prepared using chemical bath deposition (CBD), and the structural, optical and photoconductive properties were investigated. The crystal structure of CdS thin film was studied by X-ray diffraction. The crystallite size, dislocation density and lattice constant of CBD CdS thin films were investigated. The dislocation density of CdS thin films initially decreases with increasing film thickness, and it is nearly constant over the thickness of 2,500 ${\AA}$. The dislocation density decreases with increasing the crystallite size. The Urbach energies of CdS thin films are obtained by fitting the optical absorption coefficient. The optical band gap of CdS thin films increases and finally saturates with increasing the lattice constant. The Urbach energy and optical band gap of the 2,900 A-thick CdS thin film prepared for 60 minutes are 0.24 eV and 2.83 eV, respectively. The activation energies of the 2,900 ${\AA}$-thick CdS thin film at low and high temperature regions were 14 meV and 31 meV, respectively. It is considered that these activation energies correspond to donor levels associated with shallow traps or surface states of CdS thin film. Also, the value of ${\gamma}$ was obtained from the light transfer characteristic of CdS thin film. The value of ${\gamma}$ for the 2,900 A-thick CdS thin film was 1 at 10 V, and it saturates with increasing the applied voltage.

• 공업화학
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• 제21권2호
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• pp.178-182
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• 2010

다양한 $TiO_2$를 담체로 한 Pt계 촉매에서 NOx, soot의 동시 제거 반응에 대한 연구를 수행하였다. 실험은 각 촉매를 NOx와 soot의 반응을 독립 또는 동시에 반응시킨 조건으로 수행하였으며 그 결과 $TiO_2$의 종류에 따라 서로 상이한 NOx 제거능력과 soot 산화력을 나타내었다. 또 NOx 독립 실험 시 생성된 $NO_2$ 양과 soot 산화시작온도가 저온으로 이동하는 정도가 관계가 있었다. 담체의 물성 중 Pt의 뭉침현상에 결정적 역할을 미치는 비표면적과 촉매의 환원력에 영향을 미치는 crystallite size가 NO의 $NO_2$ 전환반응에 밀접한 관계를 가지는 것으로 조사되었다. 따라서 반응의 중요한 인자는 촉매에 사용되는 담체의 물리화학적 특성임을 알 수 있었다.

• Korean Chemical Engineering Research
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• 제51권2호
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• pp.195-202
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• 2013

본 연구에서는 Titanium(IV) sulfate($Ti(SO_4)_2$)와 암모니아수로부터 수열합성법을 이용하여 비교적 낮은 합성온도($80{\sim}100^{\circ}C$)와 상압에서 소성과정을 거치지 않고 $TiO_2$ 분말을 제조하였고, $TiO_2$ 제조 시 반응온도, 반응물의 초기농도, 혼합용액의 pH와 같은 반응조건에 따른 $TiO_2$ 입자의 결정구조와 입자분포, 형상 등과 같은 물리적 특성을 고찰하였다. 제조한 시료는 UV 조사 하에 Brilliant Blue FCF(BB-FCF)의 광분해 실험을 실시하여 광분해 성능과 DRS 분석을 통해 광촉매 활성을 비교하였다. 제조한 시료의 물성은 XRD, SEM, PL, 입도분포 측정을 통하여 확인하였다. Titanium(IV) sulfate($Ti(SO_4)_2$)의 초기농도가 증가할수록 $TiO_2$의 평균 입자크기와 결정화도는 증가하였고 광촉매 활성은 감소하였다. 혼합용액의 pH가 높을수록 평균 입자크기는 감소하였고 광촉매 활성은 증가하였다. 반응온도가 높을수록 결정화도와 광촉매 활성은 증가하였다. 이상의 결과들로부터 $Ti(SO_4)_2$와 암모니아수를 이용한 비교적 낮은 합성온도와 상압에서의 수열합성법으로도 순수한 anatase 결정구조의 $TiO_2$가 제조됨을 확인할 수 있었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.73-76
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• 1997

Nanocrystalline materials have been modeled as a mixture of the crystallite and the grain boundary phases. The mechanical property has been calculated using the rule of mixtures based on the volume fractions. The critical grain size concept suggested by Nieh and Wadsworth and porous material model suggested by Lee and Kim were applied to the calculation. The theoretical results fit very well with the experimental values