• Journal of Aerospace System Engineering
• /
• v.10 no.1
• /
• pp.66-73
• /
• 2016

Space propulsion system produces required thrust for satellites and space launch vehicles by using chemical reactions of a liquid fuel and a liquid oxidizer typically. For example, monomethylhydrazine-dinitrogen tetroxide, liquid hydrogen-liquid oxygen and RP-1-liquid oxygen are conventional combinations of liquid propellants used for the liquid propulsion system. Among several liquid propellants, the monomethylhydrazine is expecially preferred for a satellite fuel due to its better storability in liquid phase during a relatively long mission period under a space environment. Thus, a development importance of a bipropellant system using the monomethylhydrazine fuel is recognized recently as the national space program proceeds on a large scale. The objective of the present study is to review a foreign research trend of a thermal decomposition reaction of monomethyhydrazine to understand a fundamental basis of its chemical reaction to prepare for domestic development in future.

• Bulletin of the Korean Chemical Society
• /
• v.10 no.3
• /
• pp.262-269
• /
• 1989

The gas phase thermal decomposition of 1-bromo-3-chloropropane in the presence of radical inhibitor was studied by using the conventional static system. The mechanism of unimolecular elimination channel is shown below. [...] In this scheme, the total molecular dissociation rate constant, ($k_1\;+\;k_2$), for the decomposition of $BrCH_2CH_2CH_2Cl$ was determined by pyrolyzing the $BrCH_2CH_2CH_2Cl$ in the temperature range of $380-420^{\circ}C$ and in the pressure range of 10∼100 torr. To obtain $k_3\;and\;k_4,\;and\;to\;obtain\;k_1\;and\;k_2$ independently, the thermal decompositions of allyl chloride and allyl bromide were also studied. The Arrhenius parameters for each step are as follows; $log\;A_{\infty}\;=\;14.20(sec^{-1}),\;E_a$ = 56.10(kcal/mol) for reaction path 1; $log\;A_{\infty}\;=\;12.54(sec^{-1}),\;E_a$ = 49.75(kcal/mol) for reaction path 2; $log\;A_{\infty}\;=\;13.41(sec^{-1}),\;E_a$ = 50.04(kcal/mol) for reaction path 3; $log\;A_{\infty}\;=\;12.43(sec^{-1}),\;E_a$ = 52.78(kcal/mol) for reaction path 4; Finally, the experimentally observed pressure dependence of the rate constants in each step is compared with the theoretically predicted values that are obtained by the RRKM calculations.

• Journal of Fashion Business
• /
• v.7 no.1
• /
• pp.27-37
• /
• 2003

This study is the first part of the research to reveal the effects of somatotype characteristics on body temperature control reaction as well as thermal sensation. Nine healthy female collegians (classified into 3 body types of thin, normal, and obese according to Rohrer index) living in Busan were chosen as the subjects. The following are the results: Significant differences of skin temperature appeared in the parts of epigastrium (thin/normal>obese), anterior forearm (normal>thin/obese), and anterior leg (obese > thin/normal) as well as mean skin temperature. Mean skin temperature temporarily dropped owing to the exercise but tended to recover as time went by. Skin temperature of normal/thin shows higher than obese type. The change of skin temperature was noticed in the order of forehead > epigastrium > anterior forearm > anterior leg > anterior thigh (obese type) ; epigastrium > forehead > anterior forearm > anterior thigh > anterior leg (normal type) ; epigastrium > forehead > anterior forearm > anterior thigh > anterior leg (thin type, before and after exercise); epigastrium > forehead > anterior forearm > anterior leg > anterior thigh (thin type, during exercise). Significant differences were shown in the temperature change inside clothes according to somatotypes. No significant differences were revealed in thermal sensation, moisture sensation, and comfortable sensation according to body types and time.

• Transactions of the Korean hydrogen and new energy society
• /
• v.14 no.4
• /
• pp.298-304
• /
• 2003

The thermal behavior of $NiFe_2O_4$ prepared by a solid-state reaction was investigated for $H_2$ generation by the thermochemical cycle. The reduction of $NiFe_2O_4$ started from $800^{\circ}C$, and the weight loss was 0.2-0.3 wt% up to $1000^{\circ}C$. In the $H_2O$ decomposition reaction, $H_2$ was generated by oxidation of reduced $NiFe_2O_4$. The crystal structure of $NiFe_2O_4$ maintained during the redox reaction of 5 cycles. From this observation, the lattice oxygen in $NiFe_2O_4$ is released without the structural change during the thermal reduction and oxygen deficient $NiFe_2O_4$ can be restored to the spinel structure of $NiFe_2O_4$.

• Proceedings of the Korean Institute of Resources Recycling Conference
• /
• 2003.10a
• /
• pp.116-121
• /
• 2003

In this study, the thermal degradation process has been investigated at various reaction temperature$(350{\sim}400^{\circ}C)$ and times$(30{\sim}120\;min)$ in order to recycle waste plastic films as solid state wax. Waste plastic films were easily melted by adding a small amount of waxes. The effects of wax addition and nitrogen flow rate on their thermal degradation properties were investigated. FT-IR, GPC and viscometer were used to analyze properties of the solid wax including the structure, molicular weight distribution and melt viscosity. The average molecular weight of solid wax was decreased with increasing the reaction time, temperature and amount of wax added, Also, the viscosity of solid wax decreased with increasing the stirring speed at a constant reaction temperature and time, and its viscosity got close to zero above $390^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.6
• /
• pp.393-400
• /
• 2017

For comparison to the Li-ion battery, evaluating a thermal battery must consider additional variables. The first one is the temperature difference between the battery and its unit cell. Thermal batteries and their unit cells have a temperature difference that is caused by the thermal battery activation mechanism and its shape. The second variable is the electrochemical reaction steps. Most Li-ion batteries have a constant electrochemical reaction at the electrode, and battery voltage is affected when the concentration of Li ions is changed. However, a thermal battery has several steps in its electrochemical reaction, and each step has a different potential. In this study, we used unit cell discharge tests based on interpolating a 4D lookup table to estimate the performance of a thermal battery. From the test results, we derived an estimation algorithm by interpolating the table, which is queried from specified profile groups. As a result, we found less than a 5 percent difference between estimation and experiment at the 1.3 V cut-off time.

• 한국전산유체공학회:학술대회논문집
• /
• 2004.03a
• /
• pp.146-153
• /
• 2004

The Numerical study has been carried out to investigate the effects of chemical reaction and thermal radiation on the rocket plume flow-field at various altitudes. The theoretical formulation is based on the Navier-Stokes equations for compressible flows along with the infinitely fast chemistry and thermal radiation. The governing equations were solved by a finite volume fully-implicit TVD(Total Variation Diminishing) code which uses Roe's approximate Riemann solver and MUSCL(Monotone Upstream-centered Schemes for Conservation Laws) scheme. LU-SGS (Lower Upper Symmetric Gauss Seidel) method is used for the implicit solution strategy. An equilibrium chemistry module for hydrocarbon mixture with detailed thermo-chemical properties and a thermal radiation module for optically thin media were incorporated with the fluid dynamics code. In this study, kerosene-fueled rocket was assumed operating at O/F ratio of 2.34 with a nozzle expansion ratio of 6.14. Flight conditions considered were Mach number zero at ground level, Mach number 1.16 at altitude 5.06km and Mach number 2.9 at altitude 17.34km. Numerical results gave the understandings on the detailed plume structures at different altitude conditions. The diffusive effect of the thermal radiation on temperature field and the effect of chemical recombination during the expansion process could be also understood. By comparing the results from frozen flow and infinitely fast chemistry assumptions, the excess temperature of the exhaust gas resulting from the chemical recombination seems to be significant and cannot be neglected in the view point of performance, thermal protection and flow physics.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.543-546
• /
• 2017

Test equipment was designed and manufactured to evaluate thermal reaction characteristic of internal insulators of solid rocket motor. Test is allowed up to chamber pressure 2,500 psi, burn-time 40 s. It is possible to observe and to compare thermal reaction characteristic for a few materials simultaneously, under the condition that the ablation occurs. In efficient average chamber pressure 878 psi, efficient burn-time 10.7 s and gas velocity 100 m/s, test was executed for confirming safety of equipment, being 4 test materials inserted simultaneously. Basic data for understanding thermal characteristic of internal insulator, that is, pressure-time curve, temperature-time curve in the test sample, and thermal destruction depth of test samples was gained successfully.

• Journal of the Korean Institute of Gas
• /
• v.18 no.4
• /
• pp.27-34
• /
• 2014

In this study, we evaluated an effect of the tempered materials on the thermal runaway characteristics in the resol resin synthesis reaction using the adiabatic calorimetry of vent sizing package 2(VSP2). The kinetic parameters, such as an activation energy and heat of reaction, were estimated using the test results. As the results, the instantaneous characteristics to express the intensity of runaway reaction decreased at the low solid content. However, the sudden loss of the tempered materials triggered the second runaway reaction rapidly. In this condition, the heat of reaction and the activation energy of phenol and p-formaldehyde were about 157 kJ/mol and 60 kJ/mol, respectively.

• Biomedical Science Letters
• /
• v.10 no.2
• /
• pp.129-135
• /
• 2004

The study was carried out through measuring the temperature and humidity of the indoor/outdoor space and the distribution of interior thermal condition, and investigating the effect of loess materials on human body. The purpose of this study is to analyze the change of dry bulb temperature and relative humidity and correlation of thermal reaction of human body with ASHRAE (American Society of Heating, Refrigerating and Air-conditioning) comfort chart in the loess interior space. In the view point of biomedical sciences, loess interior space provides optimum thermal conditions for human thermal sensation.