• Environmental Engineering Research
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• 제12권5호
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• pp.211-217
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• 2007

Polycyclic aromatic hydrocarbon growth from cyclopentadiene (CPD) pyrolysis was investigated using a laminar flow reactor operating in a temperature range of 600 to $950^{\circ}c$. Major products from CPD pyrolysis are benzene, indene and naphthalene. Formation of observed products from CPD is explained as follows. Addition of the cyclopentadienyl radical to a CPD $\pi$-bond produces a resonance-stabilized radical, which further reacts by one of three unimolecular channels: intramolecular addition, C-H bond $\beta$-scission, or C-C bond $\beta$-scission. The intramolecular addition pathway produces a 7-norbornenyl radical, which then decomposes to indene. Decomposition by C-H bond $\beta$-scission produces a biaryl intermediate, which then undergoes a ring fusion sequence that has been proposed for dihydrofulvalene-to-naphthalene conversion. In this study, we propose C-C bond $\beta$-scission pathway as an alternative reaction channel to naphthalene from CPD. As preliminary computational analysis, Parametric Method 3 (PM3) molecular calculation suggests that intramolecular addition to form indene is favored at low temperatures and C-C bond $\beta$-scission leading to naphthalene is predominant at high temperatures.

• Korean Chemical Engineering Research
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• 제53권5호
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• pp.632-637
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• 2015

Mesoporous $TiO_2$ granules were prepared by spray pyrolysis using nano-sized titania particles which were synthesized by a hydrothermal method, and they were evaluated as the photoanode of dye-sensitized solar cells. To enhance the cell efficiency, nanoparticles within granules were chemically interconnected by adding titanium ethoxide (TEOT) to colloidal spray solution. The resulting titania particles had anatase phase without forming rutile. $TiO_2$ granules obtained showed about 400 nm in size, the specific surface area of $74-77m^2/g$, and average pore size of 13-17 nm. The chemical modification of $TiO_2$ granules by adding TEOT initially to the colloidal spray solution was proved to be an effective way in terms of increasing both the light scattering within photoanode and the lifetimes of photo-excited electrons. Consequently, the light-harvesting efficiency of TEOT-modified granules (${\eta}=6.72%$) was enhanced about 14% higher than primitive nanoparticles.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.299-303
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• 1991

A lamp heated LPCVD equipment has been made. Wafer is heated by an array of fifteen tungsten halogen lamps above the front side of a wafer and pyrometer views the back side of the wafer through $CaF_2$ window. Reactor which consisits of a quartz window and a water cooled-stainless steel plate can be evacuated to $5{\times}10^{-3}$ torr with a rotary vane pump. By pyrolysis of $SiH_4$ at about $600^{\circ}C$, polysilicon has been formed on the silicon dioxide film. The measured results show that thickness nonuniformity is 15% and temperature nonuniformity is 1.1%. Because activation energy of pyrolysis of $SiH_4$ is very high, about 1.8eV, small temperature variation will induce large thickness nonuniformity. The main cause of temperature nonuniformity is unsymmetry of lamp power and an unbalanced cooling structure. Charls & Evans' SIMS result shows that the oxygen content in the deposited polysilicon is comparable to that of silicon substrate but carbon content is ten times higher.

• 한국연소학회지
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• 제15권3호
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• pp.48-56
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• 2010

Performances of power generation engine were investigated with syngas from RPF. A stoker type, multi-staged pyrolysis-gasification system, was employed for syngas generation and the syngas was refined with the sequential cleaning processes composed of a gas cooler, a bag filter and a wet scrubber. 20 kWe commercial syngas power generation engine was adopted to burn the cleaned syngas which is mainly composed of hydrogen, carbon monoxide, carbon dioxide and methane. The performance of the engine was tested with various syngas compositions and the results were compared to LNG case. Electric power output, exhaust gas temperature, and emission characteristics were measured, and the efficiency of engine generation was investigated as a function of load of power generation.

• 한국전기전자재료학회논문지
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• 제14권10호
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• pp.828-834
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• 2001

Zinc oxide (ZnO) films deposited on indium (In) films were post-annealed in a rapid thermal anealing (RTA) system. The ZnO/In films were RTA-treated in air or a vacuum ambient. The crystallographic properties and surface morphologies of the films were studied before and after the RTA by X-ray diffraction(XRD) and scanning electron microscopy (SEM), respectively. The resistivity variation of the films with RTA temperature and time was measured by the 4-point probe method. Auger electron spectroscopy (AES) was carried out to figure out the redistribution of indium atoms in the ZnO films. The resistivity of the ZnO/In films decreased to 2$\times$10$\^$-3/ Ωcm by diffusion of the In. The In diffusion into the ZnO films roughened the surface of ZnO films. The results of depth profile by AES showed a hump of In atoms around ZnO/In interface after the RTA at 800 $\^{C}$. The effects of temperature time and ambient during the RTA on the structural and electrical properties of the ZnO/In films were discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1499-1502
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• 2005

Dense $BaMgAl_{10}O_{17}:Eu^{2+}$ phosphor particles with a spherical shape have been synthesized through spray pyrolysis method using basic aluminum nitrate precursor as a spray solution. This $BaMgAl_{10}O_{17}:Eu^{2+}$ particles prepared by the spray pyrolysis have shown the stronger emission intensity compared to the commercially-available $BaMgAl_{10}O_{17}:Eu^{2+}$. However, thermal stability of the BAM:Eu b lue phosphor is very poor due to changing from $Eu^{2+}$ to $Eu^{3+}$ at the thermal process, so brightness of the phosphor decreases. To improve the thermal stability of the dense BAM:Eu phosphor, the spherical BAM:Eu particles were coated with pure $BaMgAl_{10}O_{17}$ layer using the hydrolysis reaction in a solution system. The synthesized powders were characterized by XRD, SEM and PL. On the other hand, the emission properties of the BAM:Eu phosphors coated with $BaMgAl_{10}O_{17}$ layer before and after thermal treatment at $500^{\circ}C$ for 30 min were estimated under VUV excitation. The brightness of the coated phosphor was higher than that of the uncoated phosphor. Also, the coating thickness of BAM layer in the BAM:Eu particles was optimized.

• 한국분무공학회지
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• 제20권3호
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• pp.162-167
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• 2015

Recently, there has been rising interest in applying urea-SCR systems to large marine diesel engines because the International Maritime Organization (IMO) has decided to enforce NOx reduction regulations. Generally, in the case of urea-SCR of the marine diesel engine, a type of twin fluid atomizer has been using for injection of the urea solution. This study conducted to investigate an effect of the atomization of external-mixing twin fluid nozzle on the conversion efficiency of reductant. The lab-scaled experiment device was installed to mimic the urea-SCR system of the marine diesel engine for this study. In a low temperature inflow gas condition which is similar with the exhaust temperature of large marine diesel engine, this study found that the conversion efficiency of reductant of when relative big size urea solution droplets are injected into exhaust gas stream can be larger than that of when small size urea solution droplets are injected. According to results of this study, the reason was associated with decrease of reaction rate constant caused from temperature drop of inflow gas by assist air of twin fluid atomizer.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.283-286
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• 1999

Transparent conductive aluminum-doped ZnO(AZO) films Were prepared by a ultrasonic spray pyrolysis method at the substrate temperature below 23$0^{\circ}C$. A vertical type hot wall furnace was used as a reactor in the deposition system. Zinc acetate dissolved in methanol was selected as a precursor. The substrate temperature was varied from 18$0^{\circ}C$to 24$0^{\circ}C$. Aluminum (Al) was doped into ZnO films by incorporating anhydrous aluminum chloride (AlCl$_3$) in the zinc acetate solution. The proportion of the Al in the starting solution was varied from 0 wt % to 3.0 wt %. The crystallographic properties and surface morphologies of the films were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The resistivity of the films was measured by the Van der Pauw method, and the mobility and carrier concentration were obtained through the Hall effect measurements Transmittance was measured in the visible region. The effects of substrate temperature and aluminum content in the starling solution on the structural and electrical properties of the AZO films are discussed

• 한국전기전자재료학회논문지
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• 제13권8호
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• pp.658-666
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• 2000

Sb and Sb-Fe doped SnO$_2$film resistors were prepared by spray pyrolysis technique. The effects of Sb and Sb-Fe addition on TCR and electrical properties of SnO$_2$film resistors were studied. Also the dependence of electrical properties on the substrate temperature and substrate-nozzle distance was investigated. The Sn-Sb system with 7.9 mol% SbCl$_3$(STO-406) and Sn-Sb-Fe systems with 7.3 mol% SbCl$_3$+7.3 mol% FeCl$_3$(STO-407) and with 3.4 mol% SbCl$_3$+7.7mol% FeCl$_3$(STO-408) were prepared. Both of the systems Sn-Sb and Sn-Sb-Fe represented nonlinearity of TCR with temperature. As the amount of Fe increased TCR was shifted to positive direction. Decreasing Sb or increasing Fe caused resistivity to increase. Also increasing Fe caused the crystallization degree of rutile structure in SnO$_2$film to decrease. The electrical resistivity decreased with increasing substrate temperature The resistivity decreased with increasing substrate-nozzle distance in the ranges from 15 to 25 cm and increased rapidly at the distance over 25cm.

• 한국세라믹학회지
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• 제26권3호
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• pp.347-360
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• 1989

Spinel, mullite, forsterite and cordierite composition powders were synthesized from Mg(NO3)2.6H2O, Al(NO3)3.9H2O and SiCl4-ethanol solution by spray pyrolysis method and the sinterability of these powders were investigated. The bulk density of spinel and mullite specimens sintered at 1,$700^{\circ}C$ for 1hr was 3.56g/㎤(99.5% relative density) and 3.16g/㎤(99.7% relative density), respectively. (Green compacts were made from powders prepared at 1,00$0^{\circ}C$). The bulk density of forsterite and cordierite specimens sintered at 1,480 and 1,40$0^{\circ}C$ for 2hrs were 3.217 and 2.155g/㎤, respectively. (Green compacts were made from powders prepared at 1,00$0^{\circ}C$). The constituent compositions of spinel and mullite specimens sintered at 1,$700^{\circ}C$ for 1hr were 27.5wt% MgO and 70.5wt% Al2O3, respectively. Vickers microhardness and fracture toughness of spinel sintered at the above condition were 13.7GPa and 2.6MN.m3/2, respectively, and room temperature bending strength, 425MPa, was nearly maintained even at the elevated temperature. In the case ofmullite specimens, those values were 13.5GPa, 2.2MN/m3/2 and 430MPa, respectively.