• Bulletin of the Korean Chemical Society
• /
• v.18 no.6
• /
• pp.612-618
• /
• 1997

$LiMn_2O_4$ powders were prepared by burning and subsequent calcination of PEG-metal nitrate precursor. After the burning stage of the precursor, some minor phases such as $Mn_2O_3$ (or $Mn_3O_4$), MnO, and carbonate were formed and single phases of $LiMn_2O_4$ were obtained by further calcinations above 400 ℃. From thermal analysis of the precursor, a violent thermal decomposition, which was indicated by a drastic weight loss accompanied by a sharp and strong exothermic peak, was observed and probably caused by an oxidation-reduction reaction between oxidizer and fuel. The formation of the minor phases could be explained in terms of the burning behavior of the precursor by employing valence concepts of propellant chemistry. The calcined powders were composed of submicron-sized but highly agglomerated particles and showed very broad particle size distribution.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.10a
• /
• pp.166-169
• /
• 2004

This paper describes the design, installation and certification activity of a combustion test facility of subscale thrust chambers propelled by pressure-fed liquid oxygen and kerosene, and suggests major key issues considered at each development stage of the facility

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2012.05a
• /
• pp.493-497
• /
• 2012

The rocket engine test facility(ReTF) was improved for hot firing tests of 7 ton-class liquid rocket engine combustion chamber, which will be used for the third stage of the Korea Space Launch Vehicle II(KSLV-II), considering convenience of operation and maintenance, flexibility and safety. In this paper, main modifications and functions of improved ReTF were described. 초 록

• Journal of the Korean Society of Propulsion Engineers
• /
• v.22 no.6
• /
• pp.126-133
• /
• 2018

A liquid rocket engine experiences various static loads in flight, such as high pressures due to propellents, thrust and thermal loads due to cryogenic liquid oxygen and combustion gas with extreme vibration. During the engine development stage, structural analyses and investigation on the strain measured from ground firing tests are necessary for determining the structural reliability of the engine. In this study, the strain characteristics, obtained from the ground firing tests of a 75 tonf-class engine, were analyzed.

• Journal of Korean Society for Atmospheric Environment
• /
• v.25 no.2
• /
• pp.108-121
• /
• 2009

The suspended particulate matters have been collected on membrane filters and glass fiber filters by an 8-stage cascade impactor for 2 years (Sep. 2005${\sim}$Sep. 2007) in Kyung Hee University-Global Campus located on the border of Yongin and Suwon. The 20 chemical species (Al, Mn, Si, Fe, Cu, Pb, Cr, Ni, V, Cd, Ba, $Na^+$, ${NH_4}^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, ${NO_3}^-$, and ${SO_4}^{2-}$) were analyzed by an ICP-AES and an IC after performing proper pre-treatments of each sample filter. Based on these chemical information, the PMF receptor model was applied to identify the source of ambient size-by-size particulate matters. The receptor modeling is the one of the statistical methods to achieve resonable air pollution management strategies. A total of 10 sources was identified in 9 size-ranges such as long-range transport, secondary aerosol, $NH_{4}NO_{3}$ related source, coal combustion, sea-salt, soil, oil combustion, auto emission, incineration, and biomass burning. Especially, the secondary aerosol source assorted in fine and coarse modes was intensively studied.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.11
• /
• pp.874-882
• /
• 2013

Kerosene(Jet A-1), one of the propellants for each stage's engine of the Korea Space Launch Vehicle-II(KSLV-II), functions as coolant at the same time as it flows inside the cooling jacket of the combustion chambers and is injected through the film cooling holes. A physical surrogate mixture model to reproduce the thermophysical characteristics of Jet A-1 has been selected and the thermodynamic/transport properties of the model fuel under high pressure including supercritical conditions have been estimated using SUPERTRAPP(NIST SRD4). Comparisons with the measured properties suggest that proposed database can be used to extract properties of Jet A-1 for conjugate heat transfer analysis of liquid propellant rocket engine thrust chambers. Predicted combustion/cooling performance of regeneratively cooled thrust chambers shall be validated through comparisons with upcoming firing test results.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.21 no.5
• /
• pp.46-53
• /
• 2017

This paper deals with an acoustic model for a lean premixed gas turbine combustor composed of three stages: premixing chamber, nozzle and flame tube. Our model is given as an acoustic transfer function whose input is a heat release rate perturbation and output is a velocity perturbation at a flame location. We have shown that the resonance frequencies are functions of three round-trip frequencies of acoustic wave in each stage, and area ratios between stages. By analyzing poles of the acoustic transfer function, we could characterize resonant frequencies and their dependency on various system parameters of a combustor. It was found that our analytic findings match with existing numerical and experimental results in literature.

• Applied Chemistry for Engineering
• /
• v.19 no.6
• /
• pp.645-651
• /
• 2008

In this study, the new solubility data at high pressure condition applicable to pre-combustion $CO_2$ capture system were found. Experiments were conducted within the temperature range of $40{\sim}80^{\circ}C$ while increasing the pressure from 0 to 50 bar. The effect of MDEA (N-methyldiethanolamine) concentration was studied by varying the concentration from 30 to 50 wt%. In order to improve the absorption rate of MDEA, piperazine was added in ranging of 5~10 wt% into the MDEA solution as a activator. From this experiment, the equilibrium partial pressure was increased with increasing MDEA concentration in absorbent and reaction temperature. Also absorption rate was increased with increasing the reaction temperature. It was noted that the mixture of piperazine and MDEA aqueous solution showed faster absorption rate by 2.5 times than only the MDEA aqueous solution with 40 wt% cencentration at initial reaction stage and also increased absorption capacity by 16%.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.28 no.2
• /
• pp.171-183
• /
• 1992

In this paper, the behaviour of cavitation erosion, influence of corrosion and corrosion control on slide bearing metals for internal combustion engine were investigated, and this experiment was done by the vibratory cavitation erosion tester. The main results obtained are as follows: 1. With decreasing the space between horn and specimen, the weight loss and its rate increased step by step. But the weight loss and its rate of 0.2mm space decreased conversely more than that of 0.4mm space at early stage. 2. The weight loss and its rate with change of pH were appeared to the order of pH2>pH12>pH7>pH4. And the weight loss and its rate at pH 4 decreased at best. 3. The weight loss and its rate by cavitation erosion for bearing metals were shown to the order of W.M7>W.M1>K.M4. 4. There appeared mainly small pit hole at pH2, and appeared the pit of netting thread type at pH12 by the results of the damaged surfaces at pH2 and pH12 environments that were sensitive to cavitation erosion. 5. With increasing the viscosity of lubricating oil, the weight loss rate by cavitation erosion became dull at the space below 0.5mm. 6. The protective efficiency of cavitation erosion-corrosion is superior inhibitor of chormate(25 ppm) to cathodic protection.

• 연구논문집
• /
• s.33
• /
• pp.5-16
• /
• 2003

Fuel distribution, combustion, and flame propagation characteristics of heavy duty engine with the liquid phase LPG injection(LPLI) were studied in a single cylinder engine. Optically accessible single cylinder engine and laser diagnostics system were built for quantifying fuel concentration by acetone PLIF(planar laser induced fluorescence) measurements. In case of Otto cycle engine with large bore size, the engine knock and thermal stress of exhaust manifold are so critical that lean burn operation is needed to reduce the problems. It is generally known that fuel stratification is one of the key technologies to extend the lean misfire limit. The formation of rich mixture in the spark plug vicinity was achieved by open valve injection. With higher swirl strength(Rs=3.4) and open valve injection, the cloud of fuel followed the flow direction and the radial air/fuel mixing was limited by strong swirl flow. It was expected that axial stratification was maintained with open-valve injection if the radial component of the swirling motion was stronger than the axial components. The axial fuel stratification and concentration were sensitive to fuel injection timing in case of Rs=3.4 while those were relatively independent of the injection timing in case of Rs2.3. Thus, strong swirl flow could promote desirable axial fuel stratification and, in result, may make flame propagation stable in the early stage of combustion.