• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.160-167
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• 2000

We investigated a uniform temperature zone, produced by double flame structure of a coflow CH4/air partially premixed flame, to be used as a temperature calibration source for laser diagnostics. A broadband N2 CARS(coherent anti-Stokes Raman spectroscopy) system with a modeless laser was used for temperature measurement. When the stoichiometric ratio was 1.5, we found the uniform temperature zone in radial direction of the flame of which the averaged temperature was 2110 K with standard deviation 24 K. In the stoichiometric ratio range between 2.0 and 2.5, we found very stable temperature-varying zones in vertical direction at the center of the flame. The size of the zone was approximately 15 mm and it covered a temperature range from 300 K to 1900 K. We also suggest that this zone can be used as a calibration source for 2-D PLIF(planar laser induced flurescence) temperature measurement.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.3
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• pp.175-186
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• 2004

In this paper, we developed the dynamic model of a fuel cell system suitable for controller design and system operation. The transient phenomena captured in the model include the flow characteristics and inertia dynamics of the compressor, the intake manifold filling dynamics, oxygen partial pressures and membrane humidity on the fuel cell voltage. In the simulations, we paid attention to the transient behavior of stack voltage and compressor pressure, stoichiometric ratio. Simulation results are presented to demonstrate the model capability. For load current following, stack voltage dynamic characteristics are plotted to understand the Electro-chemistry involved with the fuel cell system. Compressor pressure and stoichiometric ratio are strongly coupled, and independent parameters may interfere with each other, dynamic response, undershoot and overshoot.

• Journal of the korean Society of Automotive Engineers
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• v.8 no.4
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• pp.13-23
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• 1986

The power of an international combustion engine depends on its ability to inhale air whether it is naturally aspirated or turbocharged. The use of fuel injection allows engine efficiency to be increased through a more even distribution of the air/fuel ratio throughout the engine's operation range. The theoretical value for complete combustion in an engine is commonly refered to as stoichiometric, which means that we require 14.7 parts of air to 1 part of gasoline. This stoichiometric ratio can be more closely maintained with electronically controlled fuel injection than it can with carburetion. Because of the greater efficiency of the engine using fuel injection, a horse power increase of at least 10% is produced over its carburetor version. In addition, better fuel economy and less exhaust emissions are also obtained.

• Carbon letters
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• v.4 no.4
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• pp.175-179
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• 2003

It is well established that halogenated fullerene derivatives act as synthetic intermediates for further substitution via replacement with nucleophlies. In the present work, systematic studies were carried out on the synthesis of bromofullerenes under different experimental conditions. The effect of reaction time on the product formed was observed. We observed the formation of new compound of bromofullerenes in a different stoichiometric ratio i.e., $C_{60}Br_{14}$; in addition to previous reported bromofullerenes in the stoichiometric ratio of $C_{60}Br_6$, $C_{60}Br_8$, and $C_{60}Br_{24}$. The new derivative of bromofullerene was isolated and well characterized by various analytical techniques like FT-IR, TGA, DSC, and elemental analysis. In this paper, detail of the synthesis and characterization of the bromofullerene prepared are described. The yields obtained were better than those reported previously.

• Journal of the Korean Chemical Society
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• v.30 no.4
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• pp.394-402
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• 1986

Detonation reaction in L.P.G./$O_2$ mixture gas has been investigated over the L.P.G. concentration range of 3∼45 volume%. The variation of detonation velocity with mixture ratio is very interesting as it shows and inflection point near at the stoichiometric ratio. This might be ascribed to the fact that the detonation reactions at fuel-rich condition and fuel-lean condition proceed via different mechanisms. The maximum detonation velocity of 2.65km/sec occurs not at stoichiometric ratio(${\phi}$=1) but at fuel-rich condition (${\phi}$=1.57). Assuming that a stable detonation wave must propagates with the constant velocity, The upper and lower limit of detonation were determined and found to be 40.0 and 3.40 L.P.G. volume% respectively. The shock-heating technique was also utilized for the measurement of self-ignition temperature onsetting a stable detonation wave at varous mixture ratios. The self-ignition temperature at stoichiometric ratio is $742{\pm}3{\circ}K$ and the self-ignition temperature increases as the mixture ratio deviates from the stoichiometric condition.

• Cement Symposium
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• no.1
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• pp.18-22
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• 1973

A historical review of burning processes on cement manufacture has been made regarding specially to heat efficiency. In addition to these processes, two examples of stoichiometric calculation dealing with combustion such as air fuel ratio and excess air h

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.5
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• pp.402-409
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• 2009

Sodium bicarbonate ($NaHCO_3$) was used as a reactant for the removal of acid gases from a waste incinerator. The removal efficiencies of HCl and $SO_x$ were tested with a reactant mixing apparatus and a distributor installed at the bag filter inlet. It was shown that the stoichiometric ratio of $NaHCO_3$ to the acid gases which allows a removal of over 90% for both HCl and $SO_2$ was about 1.2. When a reactant mixing apparatus was installed on the duct, the removal efficiencies of HCl and $SO_2$ at the end of the duct were increased by approximately 1.5 and 3 times respectively, compared to when the apparatus was not installed. At the end of the bag filter, the removal efficiencies of the both were as high as 98% with a stoichiometric ratio of 1.35. Installing a reactant mixing apparatus on the duct and a distributor at the entrance of the bag filter and using $NaHCO_3$ as a reactant helped overcome the problem of low removal efficiencies of acid gases by dry scrubbing.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.8
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• pp.733-741
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• 2013

This is the first paper on the combustion characteristics of landfill gas in a constant volume combustion chamber for a large displacement volume commercial engine, and it discusses the fundamental characteristics of fuel from the viewpoint of thermochemistry and thermodynamics and compares these results with experimental ones. The results show that the final pressures obtained from theoretical analysis vary under the same heating value owing to the change in the constant volume specific heat owing to the difference in the burned gas composition according to the fuel gas compositions; furthermore, the stoichiometric ratios and trends of analytical and experimental pressures coincide very well, although some minor differences are observed between the two. The root cause of the difference is the heat transfer, which changes the specific heat and lowers the temperature considerably, in the real combustion process. In addition, the large chamber volume and ignition position promote the heat transfer to the wall. Finally, the fuel conversion efficiency increases as the methane mol fraction decreases, and it is maximum when the stoichiometric ratio ranges from 0.8 to 0.9. These increases due to the composition and stoichiometric ratio could sufficiently compensate the decrease due to the specific heat ratio drop, LFG might be more advantageous than pure methane in a real engine.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.177-179
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• 2012

This work presents an experimental investigation to study $NO_x$ emissions under stoichiometric air ratio and elevated pressure (2~10bar) in a High Press Combustor(HPC) equiped with double cone burner which was designed by Pusan Clean Coal Center(PC3). Exaust gas temperature and $NO_x$ emissions were measured at the end of the combustion chamber. The $OH^*$ radical concentration and $NO_x$ emission were decreased as a function of increasing ${\lambda}$ generally. On the other hand, $OH^*$ radical concentration and $NO_x$ emission increased with ${\lambda}$ pressure of the combustion chamber. $NO_x$ emissions which were governed by thermal $NO_x$, were highly increased under the elevated pressure, but slightly increased at sufficiently low fuel concentrations (${\lambda}>2.0$).

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.162-167
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• 1992

Tic and TiN layers were deposited on the stainless steel substrate by the reactive RF sputtering. Ar was used for sputtering gas and CzHz and Nz were used for reaction gas. Deposition rate increased linearly to the applied RF power, and decreased as the partial pressure ratio of sputter gas to reactive gas increased. The thin layers were stoichiometric at the partial pressure ratio of 0.03 for Tic and at partial pressure ratio of 0.05 for TiN. The morphologies and structures of the thin layers were investigated by AES, SEM and TEM. In addition, N+ ion was implanted to Tic and the resulting influence on the film and annealing effects were also examined.