• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.157-158
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• 2006

A novel nanofabrication process has been developed using two-photon crosslinking (TPC) for the fabrication of three-dimensional (3D) SiCN ceramic microstructures applicable to high functional 3D devices, which can be used in harsh working environments requiring a high temperature, a resistance to chemical corrosion, as well as tribological properties. After sequential processes: TPC and pyrolysis, 3D ceramic microstructures are obtained. However, large shrinkage due to low-ceramic yield during the pyrolysis is a serious problem to be solved in the precise fabrication of 3D ceramic microstructures. In this work, silica nanoparticles were employed as a filler to reduce the amount of shrinkage. In particular, the ceramic microstructures containing 40 wt% silica nanoparticles exhibited relatively isotropic shrinkage owing to its sliding free from the substrate during pyrolysis.

• Bulletin of the Korean Chemical Society
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• 제29권5호
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• pp.1007-1012
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• 2008

Spray pyrolysis has been found as an excellent method for the preparation of mesoporous barium sulfate at higher temperature. Ethylene glycol, a reducing agent, and solvents had good inhibition effect for the preparation of $BaSO_4$ nano particles. The $BaSO_4$ solution was sprayed at 500 & 800 ${^{\circ}C}$ using different solvents such as methanol, ethanol, propanol and n-butyl alcohol. $N_2$ adsorption-desorption isotherm revealed that $BaSO_4$ is micropore free, possessing narrow mesopores size distribution and high BET surface areas of 72.52 $m^2\;g^{-1}$ at 800 ${^{\circ}C}$ using propanol as an additive. Scanning electron microscopy (SEM) indicates that the morphology of $BaSO_4$ nano material shows uniform shell like particles. Transmission electron microscopy (TEM) proved that the resulting BaSO4 nano particles were uniform in size and the average particle size was 4-8 nm. The surface functionality and ethylene glycol peaks were assessed by Fourier transform infrared resonance (FTIR) spectroscopy. Low intensity ethylene glycol specific absorption peak was observed in propanol which proved that propanol had good inhibition effect on the structural morphology of nano particles.

• 한국분말재료학회지
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• 제25권6호
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• pp.482-486
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• 2018

Despite numerous advances in the preparation and use of GaN, and many leading-edge applications in lighting technologies, the preparation of high-quality GaN powder remains a challenge. Ammonolytic preparations of polycrystalline GaN have been studied using various precursors, but all were time-consuming and required high temperatures. In this study, an efficient and low-temperature method to synthesize high-purity hexagonal GaN powder is developed using sub-micron $Ga_2O_3$ powder as a starting material. The sub-micron $Ga_2O_3$ powder was prepared by an ultrasonic spray pyrolysis process. The GaN powder is synthesized from the sub-micron $Ga_2O_3$ powder through a nitridation treatment in an $NH_3$ flow at $800^{\circ}C$. The characteristics of the synthesized powder are systematically examined by X-ray diffraction, scanning and transmission electron microscopy, and UV-vis spectrophotometer.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.1-7
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• 2022

Interest in hydrogen productions that do not emit carbon dioxide and can produce hydrogen at a low price is increasing. Reforming and electrolysis are widely used, but they have limitations, such as carbon dioxide problems and costs. The methane can be decomposed as hydrogen and solid carbon without carbon dioxide emission at high temperatures. In this research, the methane pyrolysis experiment was conducted at 1,200℃ and 1,400℃ in a ceramic tube. The composition of the produced gas was measured by gas chromatography before carbon blocked the tube. The methane conversion rate and hydrogen selectivity were calculated based on the results. The hydrogen selectivity was derived as 60% and 55% at the highest point at 1,200℃ and 1,400℃, respectively. The produced solid carbon was expected to be carbon black and was analyzed using scanning electron microscope.

• Progress in Superconductivity
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• 제13권2호
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• pp.127-132
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• 2011

Many research groups have been manufacturing coated conductor by various processes such as PLD, MOD, and MOCVD, but the methods with production cost suitable for wide and massive application of coated conductor did not develop yet. Spray pyrolysis method adopting ultrasonic atomization was tried as one of the possible option. GdBCO precursor films have been deposited on IBAD substrate by spray pyrolysis method at low temperature and converted to GdBCO by post heat treatment. Ultrasonic atomization was used to generate fine droplets from precursor solution of Gd, Ba, and Cu nitrate dissolved in water. Primary GdBCO films were deposited at $500^{\circ}C$ and oxygen partial pressure of 1 torr. After that, the films were converted at various temperatures and low oxygen partial pressures. C-Axis oriented films were obtained IBAD substrates at conversion temperature of around $870^{\circ}C$ and oxygen partial pressures of 500 mtorr ~ 1 torr in a vacuum. Thick c-axis epitaxial film with the thickness of 0.4 ~ 0.5 ${\mu}m$ was obtained on IBAD substrate. C-axis epitaxial GdBCO films were successfully prepared by ex-situ methods using nitrate precursors on IBAD metal substrate. Converted GdBCO films have very dense microstructures with good grain connectivity. EDS composition analysis of the film showed a number of Cu-rich phase in surface. The precursor solution having high copper concent with the composition of Gd : Ba : Cu = 1 : 2 : 4 showed the better grain connectivity and electrical conductivity.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권2호
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• pp.47-53
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• 2012

In this study, the adsorption of $Cu^{2+}$ and $Cd^{2+}$ from aqueous solution on the biochar derived from used coffee grounds at different pyrolysis temperatures has been investigated as a potential low-cost treatment method for heavy metal-containing waters. Three biochar samples prepared by heating coffee sludge at temperature of $300^{\circ}C$ (B300), $500^{\circ}C$ (B500), and $700^{\circ}C$ (B700) were tested for the adsorption capacity and kinetics of Cd and Cu. Also the influencing factor of heavy metal removal by ion exchange in terms of cation exchange capacity (CEC) of each biochar was measured. Adsorption of Ca and Cu by biochar produced at higher pyrolysis temperature showed higher adsorption capacity but the optimal pyrolysis temperature based on performance and economy was known as $500^{\circ}C$. Sorption of Cu and Cd by biochar followed a Langmuir model at pH 6~6.5, attributing mainly to surface sorption. The biochar was more effective in Cu and Cd sorption than activated carbon (AC), with BC 500 being the most effective, which indicates that sorption of Cd and Cu by coffee sludge biochar is partly influenced by chemical sorption on surface functional group as well as physical sorption.

• 한국산학기술학회논문지
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• 제9권4호
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• pp.1059-1066
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• 2008

열중량반응기와 미분반응기를 이용하여 ABS의 역분해 및 생성물분포 특성을 연구하였으며 미분반응기를 이용한 실험의 열분해온도는 $400\sim450^{\circ}C$이었다. 각 상의 열분해생성물의 수율은 무게측정을 통해 얻었으며 액상생성물의 탄소수분포는 GC-SIMDIS 방법을 통해 측정하였다. 열중량분석실험에서는 측정할 수 없었던 다량의 고상잔류물의 생성을 회분식 미분반응기실험을 통해 확인학 수 있었다. 반응온도와 시간이 증가할수록 액상생성물의 수율과 평균분자량은 감소하였으나 액상생성물 중의 스티렌모노머의 생성은 두드러지게 증가하였다. ABS 열분해 반응에서 말단절단의 속도계수인 활성화에너지 값은 54.1kcal/mole이었다.

• 공업화학
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• 제10권3호
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• pp.432-437
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• 1999

폴리에틸렌 열분해실험을 반응기 크기가 $10cm^3$인 스테인레스 스틸 반응기에서 수행하였으며 이때 반응온도는 $390{\sim}450^{\circ}C$이었다. 열분해생성물인 반응생성물과 기체생성물을 분리하여 채취하였고 각 생성물의 분자량분포는 HPLC-GPC와 GC분석을 통해 얻었다. 열분해반응의 개시-종료, 전파-비전파반응, 즉 수소탈취반응, 사슬절단, 고분자물질과 라디칼과의 결합반응 등을 설명할 수 있는 random, specific 생성물의 분자랑분포에 대한 distribution balance식을 제안하였다. 말단절단 과정에 의해 저분자량의 비응축성 기체생성물 (C1~C5)이 생성되었으며 이 기체생성물의 평균분자량은 38이었다. 무작위절단과 말단절단의 속도매개변수 중의 하나인 활성화에너지는 각각 35, 17 kcal/mole 이었다.

• 청정기술
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• 제5권1호
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• pp.42-48
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• 1999

폐타이어는 환경 문제와 관련하여 오염과 재활용의 양면성을 지니고 있다. 이와 같은 폐타이어를 재활용의 측면에서 고온의 열플라즈마를 이용하여 열분해하여 가연성 가스로의 전환을 시도하였다. 폐타이어를 산소가 배제된 상태에서 열분해하여 $CH_4$, $C_2H_2$, $C_4H_{10}$등과 같은 저분자량의 탄화수소가 주성분인 가연성 가스가 다량 발생함을 GC를 이용하여 확인할 수 있었다. 타이어의 공급량이 증가할수록 가연성 가스의 구성에서 $CH_4$의 비율이 증가하였으며, 플라즈마 전력이 증가할수록 $C_2H_2$가 증가함을 확인하였다. 발생가스는 $C_4H_{10}$ 또는 $C_2H_2$등의 탄화수소가 주를 이루었으며 그 비율은 70%이상이었다. 한편 char의 온도에 따른 질량 감소 경향을 TG로 분석하여 열플라즈마 내에서 타이어의 열분해 경향을 간접적으로 유추할 수 있었다.

• 자원리싸이클링
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• 제19권1호
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• pp.3-12
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• 2010

최근 정부의 저탄소 녹색성장 정책, 신재생에너지의무할당제(RPS)의 시행 추진, 국제 유가의 지속적인 상승 등으로 인해 폐자원 에너지화에 대한 관심이 높아지고 있다. 이와 관련하여 에너지를 많이 소비하는 업계에서는 폐기물 고형연료의 사용을 추진하고 있고, 특히, 폐플라스틱의 열분해유화기술은 중소, 중견기업들이 국내에서 개발된 기술의 상용화를 적극적으로 검토하고 있다. 본 논문에서는 폐플라스틱 열분해 기술의 소개와 폐플라스틱 자원, 기술 개발 및 상업화 등에 대하여 국내의 현황을 소개하였다.