• 한국추진공학회지
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• 제24권6호
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• pp.10-15
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• 2020

본 연구는 동일한 제조법을 가지는 연소촉매 FeOOH와 Fe₂O₃를 제조하여 고체추진제에 적용 후 기계적 물성 및 연소 특성의 변화에 관한 내용이다. 동일한 제조방법을 가지는 FeOOH와 Fe₂O₃를 만들기 위하여 FeOOH를 200, 300, 400, 500℃에서 2시간 동안 소성시킨 후 XRD 결과를 확인하였다. 또한, 제조된 촉매를 고체추진제에 적용 후 기계적 물성 및 연소 특성의 변화를 나타내었다. XRD 결과상으로 FeOOH는 200~300℃사이에서 Geothite에서 Hematite로 결정상이 변화하는 것을 확인하였다. 추진제의 응력은 연소촉매의 소성온도가 높아짐에 따라 변화가 거의 없지만 연신율은 소성을 진행한 촉매를 적용 시 증가하였다. 연소속도는 소성을 하지 않은 FeOOH가 다른 촉매에 비해 약 3~5% 빠르다는 것을 확인하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1998년도 제17회 KOSCI SYMPOSIUM 논문집
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• pp.69-77
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• 1998

In order to meet the stringent emission regulations, fast light-off of a catalyst is essential to reduce the HC and CO emissions during cold start. Cranking Exhaust Gas Ignition (CEGI) method developed in this study showed that the catalyst reaches the light-off temperature in a few seconds after cold start. The CEGI system cuts off the ignition signal for a few seconds during the cranking period. so the unburned fuel-air mixture bypasses the combustion chamber and flows through the exhaust manifold. When the unburned mixture reaches two glow plugs installed upstream of the catalyst, it burns and releases the thermal energy to heat up the catalyst. Results from the FTP-75 tests showed that the exhaust emissions with the CEGI reduced by 47.7% for THC and by 88.6% for CO in the cold-transient phase of the test.

• 한국환경과학회지
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• 제26권1호
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• pp.67-78
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• 2017

Combustion of ethanol (EtOH) at low temperatures has been studied using titania- and silica-supported platinum nanocrystallites with different sizes in a wide range of 1~25 nm, to see if EtOH can be used as a clean, alternative fuel, i.e., one that does not emit sulfur oxides, fine particulates and nitrogen oxides, and if the combustion flue gas can be used for directly heating the interior of greenhouses. The results of $H_2-N_2O$ titration on the supported Pt catalysts with no calcination indicate a metal dispersion of $0.97{\pm}0.1$, corresponding to ca. 1.2 nm, while the calcination of 0.65% $Pt/SiO_2$ at 600 and $900^{\circ}C$ gives the respective sizes of 13.7 and 24.6 nm when using X-ray diffraction technique, as expected. A comparison of EtOH combustion using $Pt/TiO_2$ and $Pt/SiO_2$ catalysts with the same metal content, dispersion and nanoparticle size discloses that the former is better at all temperatures up to $200^{\circ}C$, suggesting that some acid sites can play a role for the combustion. There is a noticeable difference in the combustion characteristics of EtOH at $80{\sim}200^{\circ}C$ between samples of 0.65% $Pt/SiO_2$ consisting of different metal particle sizes; the catalyst with larger platinum nanoparticles shows higher intrinsic activity. Besides the formation of $CO_2$, low-temperature combustion of EtOH can lead to many other pathways that generate undesired byproducts, such as formaldehyde, acetaldehyde, acetic acid, diethyl ether, and ethylene, depending strongly on the catalyst and reaction conditions. A 0.65% $Pt/SiO_2$ catalyst with a Pt crystallite size of 24.6 nm shows stable performances in EtOH combustion at $120^{\circ}C$ even for 12 h, regardless of the space velocity allowed.

• 한국연소학회지
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• 제15권3호
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• pp.25-31
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• 2010

Combined technique of burner and DOC has been used for regeneration of Diesel Particulate Filter. Experiments has been performed to increase the temperature of engine exhaust gas to burn the collected soot in DPF at all conditions of operation of 3 liter diesel engine. Ignition temperature of soot can be successfully obtained by heats of burner flame and residual fuel oxidation at diesel oxidation catalyst even in the condition of oxygen deficiency. It is found that the load of air compressor and heat loss can be reduced to the level of practical application. It is also found that CO and THC emissions are not increase by additional combustion of regeneration burner.

• 한국기계기술학회지
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• 제13권4호
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• pp.101-108
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• 2011

On cold start operation of an SI engine, a catalyst shows poor performance before it reaches activation temperature. Therefore, fast warmup of the catalyst is very crucial to reduce harmful emissions. In this study, an appropriate control strategy is investigated to increase exhaust gas temperature through changes of spark timing. Combustion stability is also considered at the same time. Exhaust gas temperature and pressure of combustion chamber are measured to investigate the effects of spark timings on cold start and idle performance. Experiments showed that retarded spark timing promotes the combustion at the end of expansion stroke and increases exhaust gas temperature during cold start.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.989-994
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• 2001

Numerical simulations of high temperature catalytic combustion have been performed for the application to a gas turbine combustor. Dependences of inlet temperature and pressure on the distributions of temperature and species concentrations were investigated using plug flow model with detailed homogeneous and heterogeneous chemistries of methane-air mixtures. Honeycomb typecombustor deposited with Pt catalyst of 100mm in length and 26mm in diameter is used. The results show that rapid increase of temperature profile occurs earlier with the increase of inlet temperature and the decrease of inlet pressure. The condition which catalytic combustion is stabilized exists at certain range of inlet temperature and pressure. The state of catalytic combustion is also confirmed by the distributions of species concentration.

• 한국대기환경학회지
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• 제19권5호
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• pp.541-549
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• 2003

A basic experimental study was conducted in order to find the optimum combustion control technology to decrease the thermal NO$_{x}$, by applying the catalytic combustion method with natural gas. NO$_{x}$ emission increased with increasing space velocity due to temperature rising in the furnace. In order to overcome the low resistance to high temperature, secondary air was supplied to the CST combustor. The following secondary fuel formed combustible mixture in part, which resulted in steep increase of the exiting temperature of the 2nd catalyst bed. It led to the more generator of NO$_{x}$, 30∼60% of the 1 st catalyst bed. It might be due to the potential increase of thermal NO$_{x}$.

• 한국대기환경학회지
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• 제22권3호
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• pp.373-381
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• 2006

The catalytic combustion of toluene was investigated on the Cu-Mn oxide catalysts prepared by the deposition-precipitation method. Experiment of toluene combustion was performed with a fixed bed flow reactor in the temperature range of $100{\sim}280^{\circ}C$. Among the catalysts, 1.29Cu/Mn showed the most activity at $260^{\circ}C$. The deposition-precipitation method may be showed the potential to enhance the activity of catalysts. The catalysts were characterized by BET, scanning electron microscopy (SEM), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. On the basis of catalyst characterization data, the results showed that the surface of catalysts by deposition-precipitation method had uniform distribution and smaller particle size, which enhanced the reduction capability of catalysts. The XRD results showed that $Cu_{1.5}Mn_{1.5}O_{4}$ spinel phase was made by deposition-precipitation method, and increased catalyst activity and redox characteristic. It was assumed that the reduction step of $Cu_{1.5}Mn_{1.5}O_{4}$ spinel phase progressed $Cu_{1.5}Mn_{1.5}O_{4}\;to\;CuMnO_{2},\;and\;Cu_{2}O\;to\;CuMn_{2}O_{4}\;and\;Cu$.

• 한국수소및신에너지학회논문집
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• 제29권4호
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• pp.324-330
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• 2018

In this study a numerical study was conducted to show flow, temperature and gas distributions in a high temperature CO shift reactor which was designed specially for energy saving and then evaluated with the related experiment. Mole fractions of syngas at the end of the catalyst bed were predicted with various assumed pre-exponential factors, were compared with the corresponding experimental results and $10^8$ was finally selected as the value. With the selection, a base case was examined. It was calculated that the inlet duct attached asymmetrically to the CO shift reactor affects on the distribution of the upward momentum (+z directional). In addition, CO conversion ratio is achieved up to 90% in the catalyst bed and especially it reached up to 70% at the initial part of catalyst bed.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.739-745
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• 2017

ADN 기반 고성능 친환경 단일추진제 추력기는 독성의 하이드라진을 대체하기 위해 유럽 등지의 우주 선진국에서 활발히 연구 중에 있으며, 고성능 친환경 단일추진제 중 유일하게 우주 환경에서 시험을 통해 검증을 수행한 바 있다. 본 연구에서는 ADN 기반 고성능 친환경 단일추진제 추력기의 국내 자체 개발을 위해 추진제 및 분해 촉매를 합성하고, DSC-TG 분석을 통해 추진제의 촉매 연소 성능을 검증했다. 또한 5 N 급 액체 단일추진제 추력기를 활용하여 연소 시험을 수행하여 추진제의 촉매 연소를 확인했다.