• Title/Summary/Keyword: NTO

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Morphology Control of NTO Crystals with Various Recrystallization Techniques

  • Lee, H.Y.;K.K. Koo;Kim, K.J.;G.B. Lim;W.B. Jeong;Kim, S.H.;Kim, H.S.;Park, B.S.
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • 1997.10a
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    • pp.123-127
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    • 1997
  • Various recrystallization techniques has been applied to control morphology and size of NTO(3-nitro-1, 2, 4-triazole-5-one) crystals. With cooling method, it was found that the size of NTO at aqueous solution was controlled in the range of 5 to 500 $\mu\textrm{m}$. The spherical or cubic shapes of particles were obtained by adjusting operating conditions. Hexagonal and cubic shaped crystals of NTO were also obtained by sonication and evaporative method using aqueous solution of NTO. Their particle sizes were ranged 20 to 30 $\mu\textrm{m}$. In gas anti-solvent method with NTO/DMF and NTO/DMSO solutions, cubic type of NTO was obtained and the range of their sizes was 0.5-2$\mu\textrm{m}$.

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Crystallization Kinetics of NTO in a Batch Cooling Crystallizer (회분식 냉각 결정화기에서 NTO의 결정화 메카니즘)

  • Kim, K.J.;Kim, M.J.;Yeom, C.K.;Lee, J.M.;Choi, H.S.;Kim, H.S.;Park, B.S.
    • Applied Chemistry for Engineering
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    • v.9 no.7
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    • pp.974-978
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    • 1998
  • The kinetics of crystal growth and nucleation in dependence on the supersaturation of an aqueous solution of 3-nitro-1,2,4-triazol-5-one(NTO) were evaluated on the draft tube-baffle(DTB) crystallizer operated batchwise. The crystal growth rate is proportional to the supersaturation to the 2.9 power, and the nucleation rate to the 4.2 power. The uncleation behavior for NTO-water system in DTB crystallizer was grasped according to Mersmann's criteria. The nucleation in this crystallizer was found to act with heterogeneous nucleation and surface uncleation simultaneously. Simplified relation was derived for calculation of mean crystal size of product crystals from the batch cooling crystallizer. The obtained relation was verified by a set of experiments.

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Rapid Thermal Annealing 열처리 온도에 따른 유기태양전지용Nb:$TiO_2$/Ag/Nb:$TiO_2$ 다층 투명전극의 전기적, 광학적, 구조적 및 표면 특성 연구

  • Park, Ho-Gyun;Park, Yong-Seok;Jeong, Jin-A;Choe, Gwang-Hyeok;Na, Seok-In;Kim, Han-Gi
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.197-197
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    • 2010
  • 본 연구에서는 RF/DC dual 마그네트론 스퍼터 시스템을 이용하여 Glass 기판 상에 유기태양전지용 Nb-doped $TiO_2$ (NTO)/Ag/NTO 다층 투명전극을 성막하고 이 다층 투명전극을 $200^{\circ}C{\sim}700^{\circ}C$ 온도 범위에서 급속 열처리 (Rapid Thermal Annealing ; RTA)를 통하여 전기적, 광학적, 구조적 및 표면의 특성 변화를 연구하였다. Hall effect measurement, UV-Vis spectrometer, FESEM 분석을 통하여 다층투명전극의 전기적, 광학적, 표면분석을 하였고 Synchrotron 분석을 통하여 온도에 따른 구조변화를 분석하였다. 상온에서 성막된 다층투명전극은 30nm 두께의 NTO 박막 사이에 얇은 9nm의 얇은 Ag 층을 삽입한 구조로써 10ohm/square 이하의 매우 낮은 면저항과 ${\sim}10^{-5}\;ohm-cm$ 의 비저항, Anti-reflection 효과에 의해 85% 이상의 높은 광투과성을 나타내었다. RTA 온도가 증가함에 따라 전기적, 광학적 특성은 약간 향상되었고 비정질 구조를 유지함을 알 수 있었다. 그러나 높은 온도범위에서는 비정질 구조에서 Anatase 상으로 결정구조가 변화함을 알 수 있었고 전기적, 광학적 특성이 감소됨을 알 수 있었다. NTO/Ag/NTO 다층 투명전극을 유기태양전의 Anode로 적용하여 특성을 비교한 결과 RTA 온도가 증가함에 따라 유기태양전지의 효율 또한 증가하였고 최적화된 온도 조건에서 2.49% 의 높은 효율을 얻을 수 있었다. 이를 통해 우수한 특성을 나타내는 NTO/Ag/NTO 다층투명전극이 기존의 디스플레이 및 태양전지 등의 투명전극 재료로 주로 사용되어 온 ITO (Indium Tin Oxide) 를 대체 할 수 있는 재료로써의 가능성을 제시하였다.

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Sodium titanate as an infrared reflective material for cool roof application

  • Ullah, Mahboob;Kim, Hee Jung;Heo, Jae Gu;Roh, Dong Kyu;Kim, Dae-Sung
    • Journal of Ceramic Processing Research
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    • v.20 no.spc1
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    • pp.86-91
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    • 2019
  • A solid-state route was used to prepare sodium titanium oxide (NTO, Na2Ti3O7) as a solar heat protecting material with an impressive solar reflectance (TSR = 94.3%) using a high refractive index rutile TiO2. The solar reflectance of the synthesized NTO was measured using UV-Vis-NIR spectrophotometer. Solar reflectance property of the synthesized compound depends on the calcination temperature. The solar reflectance property of the synthesized NTO powder was compared with commercial rutile TiO2. The compound synthesized at 900 ℃ for 24 hrs had remarkable solar reflectance 94.3% than that calcined below 900 ℃. Crystalline nature, structural property, morphology and optical properties of NTO powders were characterized and analyzed using XRD, FE-SEM, EDS and UV-Vis-NIR spectrophotometer. From the results, we guessed that NTO would be a suitable "solar heat protecting candidate" for energy-saving applications in coating industries.

Structure of Yb Complex with 3-nitro-1,2,4-triazol-5-one (3-nitro-1,2,4-triazol-5-one의 Yb 착물 구조)

  • 김광주;김재경;오기환
    • Journal of the Korea Institute of Military Science and Technology
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    • v.4 no.1
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    • pp.198-206
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    • 2001
  • The structure of Yb complex with 3-nitro-1,2,4-triazol-5-one(NTO), $[Yb(NTO)3(H2O)4].5H2O$ has been investigated by X-ray diffraction method. Crystallographic data for the title compound : monoclinic, C2/c, $a=36.925(2){\AA},$ b=6.6770(4)${\AA},$ c=25.6376(15)${\AA},$ {\beta}=130.978(1)^{\circ},$ V=4772.0(5)${\AA}^3,$ Z=8, $D_c,=1.952\; Mg/m^3.$ The intensity data were collected on a Broker SMART diffractometer equipped with a CCD area detector using Mo $K\alpha$ radiation. The structure was solved by direct method and refined by full-matrix least-squares calculations to a final R value of 0.0424 for 4727 independent reflections and 335 parameters. The three carbonyls of three NTO anions and four ligand water molecules which are formed the pentagonal bipyramid are coordinated with $Yb^{3+}$ and also five water molecules are included in the form of the crystal water in the molecular structure.

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The Effect of Nb-doped TiO2 Coating for Improving Stability of NiCrAl Alloy Foam (NiCrAl 합금 폼의 안정성 향상을 위해 코팅된 Nb-doped TiO2의 효과)

  • Jo, Hyun-Gi;Shin, Dong-Yo;Ahn, Hyo-Jin
    • Korean Journal of Materials Research
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    • v.29 no.5
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    • pp.328-335
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    • 2019
  • Nb-doped $TiO_2$(NTO) coated NiCrAl alloy foam for hydrogen production is prepared using ultrasonic spray pyrolysis deposition(USPD) method. To optimize the size and distribution of NTO particles based on good physical and chemical stability, we synthesize particles by adjusting the weight ratio of the Nb precursor solution(5 wt%, 10 wt% and 15 wt%). The morphological, chemical bonding, and structural properties of the NTO coated NiCrAl alloy foam are investigated by X-ray diffraction(XRD), X-ray photo-electron spectroscopy(XPS), and Field-Emission Scanning Electron Microscopy(FESEM). As a result, the samples of controlled Nb weight ratio exhibit a common diffraction pattern at ${\sim}25.3^{\circ}$, corresponding to the(101) plane, and have chemical bonding(O-Nb=O) at 534 eV. The NTO particles with the optimum weight ratio of N (10 wt%) show a uniform distribution with a size of ~18.2-21.0 nm. In addition, they exhibit the highest corrosion resistance even in the electrochemical stability estimation. As a result, the introduction of NTO coated NiCrAl alloy foam by USPD improves the chemical stability of the NiCrAl alloy foam by protecting the direct electrochemical reaction between the foam and the electrolyte. Thus, the optimized NTO coating can be proposed for excellent protection of NiCrAl alloy foam for hydrocarbon-based steam methane reforming(SMR).

Preparation and Characterization of N-doped Na2Ti6O13@TiO2 Composites for Visible Light Activity (가시광 활성을 위한 N-doped Na2Ti6O13@TiO2 복합체 제조 및 특성 연구)

  • Duk-Hee, Lee;Kyung-Soo, Park
    • Journal of Powder Materials
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    • v.29 no.6
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    • pp.492-498
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    • 2022
  • N-doped Na2Ti6O13@TiO2 (denoted as N-NTO@TiO2) composites are successfully synthesized using a simple two-step process: 1) ball-milling of TiO2 with Na2CO3 followed by heat treatment at 900℃; 2) mixing of the prepared Na2Ti6O13 with titanium isopropoxide and calcining with urea at 500℃. The prepared composites are characterized using XRD, SEM, TEM, FTIR, and BET. The N-NTO@TiO2 composites exhibit well-defined crystalline and anatase TiO2 with exposed {101} facets on the external surface. Moreover, dopant N atoms are uniformly distributed over a relatively large area in the lattice of the composites. Under visible light irradiation, ~51% of the aqueous methylene blue is photodegraded by N-NTO@TiO2 composites, which is higher than the values shown by other samples because of the coupling effects of the hybridization of NTO and TiO2, N-doping, and presence of anatase TiO2 with exposed {101} facets.

Exhaust Plume Behavior Study of MMH-NTO Bipropellant Thruster (MMH-NTO 이원추진제 추력기의 배기가스 거동 해석 연구)

  • Kim, Hyeonah;Lee, Kyun Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.45 no.4
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    • pp.300-309
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    • 2017
  • A spacecraft obtains a reaction momentum required for an orbit correction and an attitude control by exhausting a combustion gas through a small thruster in space. If the exhaust plume collides with spacecraft surfaces, it is very important to predict the exhaust plume behavior of the thruster when designing a satellite, because a generated disturbance force/torque, a heat load and a surface contamination can yield a life shortening and a reduction of the spacecraft function. The purpose of the present study is to ensure the core technology required for the spacecraft design by analyzing numerically the exhaust gas behavior of the 10 N class bipropellant thruster for an attitude control of the spacecraft. To do this, calculation results of chemical equilibrium reaction between a MMH for fuel and a NTO for oxidizer, and continuum region of the nozzle inside are implemented as inlet conditions of the DSMC method for the exhaust plume analysis. From these results, it is possible to predict a nonequilibrium expansion such as a species separation and a backflow in the vicinity of the bipropellant thruster nozzle.

Dentoalveolar Characteristics according to facial types of Class III Malocclusion (골격성 III급 부정교합의 골격유형에 따른 치아치조특성)

  • Park, Song-Soo;Kim, Hyun-Deog;Lee, Dae-Hee;Kim, Jong-Ghee;Jeon, Young-Mi
    • The korean journal of orthodontics
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    • v.32 no.1 s.90
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    • pp.33-42
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    • 2002
  • This study was performed to compare the pattern of dentoalveolar characteristics in different vertical and anteroposterior skeletal types in skeletal Class III malocclusion. The samples selected for this study were consisted of 60 subjects(29 males and 31 females, mean age; 19.7 years) in Class III group, 43 subjects(14males and 29 females, mean age : 20.5 years) in normal group. The findings of this study were as follows : 1. The IMPA of the Class III group was smaller than that of the Class I group(p<0.01). 2. In the Class III groups, SNB and NtoPog had negative correlation with IMPA(p<0.01). The SNB and NtoPog had correlations with SNU1, FHU1 and PalU1(p<0.01) in the male samples, and in the female samples, the SNB and NtoPog had correlations with SNU1(p<0.01). 3. In the Class III male samples, SNMP, FMA, PalMP had negative correlation with IMPA(p<0.01). SNMP, FMA, PalMP had not significant correlation with SNU1, FHU1, PalU1. In the Class III female samples, FMA, PalMP had negative correlation with IMPA(p<0.01). 4. In the high angle group of Class III samples, SNU1, IMPA is smaller than that of low angle group of Class III samples(p<0.05).

A Computer Aided Drawing Check System (Global Dimension Check) (컴퓨터 지원에 의한 설계도면 검증시스템)

  • ;Ono, T.;Tsujio, S.
    • 제어로봇시스템학회:학술대회논문집
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    • 1992.10a
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    • pp.1102-1107
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    • 1992
  • Existing CAD systems do nto provide the advanced function for systematic checking of design and drafting errors in mechanical drawings. This paper describes a method for sytematic checking of global parts in mechanical drawings. The checking items are deficiency and redundancy of dimensions, input-errors in dimension figures and symbols, etc. Checking for deficiency and redundancy of global dimensions has been performed applying Graph Theory. This system has been applied to several examples and we have confirmed the feasibility of this checing method.

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