• Journal of the Korean Society of Tobacco Science
• /
• v.6 no.1
• /
• pp.39-49
• /
• 1984

In the tobacco industry, it is important to study the change of mechanical property occurring the expansion process. The purpose of this study is to attain basic data for development of a tobacco expansion method. 1 . Freon gas was adsorbed to tobacco under various conditions of temperature, relative humidity and pressure, and then the amount of freon gas adsorbed was analyzed by GC. Freon adsorption rate of Burley 21 was more than that of By104 at the same condition and about 17 $\pm$ 1% moisture content produced better adsorption rate. 2. Freon adsorbed sample were heated to about $150^{circ}C\;to\;230^{\circ}C$ in a drying oven and recycle duct form about 2 to 30 seconds, and then the change of mechanical property were measured. Heated leaf was damaged when the tissue was pressed by the force of above $0.5x10^8dyn/cm^2$. The optimum condition of no damage of the sample was below the temperature of 15$0^{\circ}C$ and heating time of 10 seconds. It was more economically advantages to treated sample in a recycle duct than to be in a drying oven. By this process, the specific volume of the heated sample was increased from 80 to 110 percent in comparison to that of untreated sample.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.1 no.1
• /
• pp.80-89
• /
• 1993

Performance simulation for a Spark Ignition Wankel rotary Engine is presented in this paper. The volume of chamber at each eccentric shaft angle is evaluated by using geometric models of housing and rotor. A thermodynamic model which includes the first law of thermodynamics, combustion and convective heat transfer from chamber contents to surroundings is imployed. A thermochemical equilibrium model which considers 10 species(CO, $CO_2$, $O_2$, $H_2$, $H_2O$, OH, O, NO, $N_2$) in the burned gas region, is also employed. Four processes of gas exchange, compression, combustion and expansion are considered and the pressure, temperature and composition of chamber gas at each eccentric shaft angle in each process are computed in this performance simulation. This performance simulation must be useful for optimal design of Spark Ignition Wankel Rotray Engine with parametric study for various design parameters and operating conditions.

• 한국연소학회:학술대회논문집
• /
• 2000.12a
• /
• pp.132-139
• /
• 2000

Oxygen enriched incineration can increase the incineration capacity for wastes and dramatically reduce air pollutant emissions such as CO and dioxine by the allowing complete combustion of wastes in incinerator. Furthermore, this technology is proven to have many benefits including an energy-saving, cost-effective, and versatile application for diverse wastes compared with the conventional air incineration technology. The reduced pollutant emissions in flue gas and higher incineration efficiency are also available when the oxygen enriched air is used for the high temperature incineration systems. On the basis of the experimental results the oxygen enrichment system is successfully applied to the rotary kiln incinerator for industrial wastes. The oxygen enriched incineration system could be allowed more compact design of incinerator and flue gas treatment system due to both increasing incineration capacity and reducing flue gas volume. Therefore, oxygen enriched incineration technology is becoming highlighted in the waste incinerator which strongly require more stable efficiency and environmentally friendly and safe operationPut Abstract text here.

• Journal of Advanced Marine Engineering and Technology
• /
• v.30 no.3
• /
• pp.403-412
• /
• 2006

The effect of a wall temperature on the soot deposition process from a diffusion flame to a solid wall was investigated in a microgravity environment to attain in-situ observations of the process. The fuel for the flames was an ethylene ($C_2H_4$). The surrounding oxygen concentration was 35% with surrounding air temperatures of $T_a=600K$. In the study, three different wall temperatures. $T_w$=300, 600, 800K, were selected as major test conditions. Laser extinction was adopted to determine the soot volume fraction distribution between the flame and burner wall. The experimental results showed that the maximum soot volume fractions at $T_w$=300, 800 K were $8.8{\times}10^{-6},\;9.2{\times}10^{-6}$, respectively. However, amount of soot deposition on wall surface was decreased because of lower temperature gradient near the wall with increasing wall temperature. A numerical simulation was also performed to understand the motion of soot particles in the flame and the characteristics of the soot deposition to the wall. The results from the numerical simulation successfully predicted the differences in the motion of soot particles by different wall temperature near the burner surface and are in good agreement with observed soot behavior that is, the 'soot line', in microgravity.

• Journal of environmental and Sanitary engineering
• /
• v.14 no.1
• /
• pp.62-69
• /
• 1999

In this study, the synthesis of PZT powder by bubble column reactor was investigated at various reaction conditions. As a result, the volume % of $NH_3$ gas used as a precipitator had no effect on the synthesis, but the more research is needed to control particle size.As a carrier gas, Ar, $O_2$ and air only increased the stirring effect but had no effect chemically on the synthesis. The calcination temperature of prepared PZT powder was about $500-600^{\circ}C$ and the meanparticle size of synthesized PZT powder was about $0.17{\mu}m$. The grain size of sintered body is about $0.5~3{\mu}m$ and this is similar with the value of commercial products.

• Explosives and Blasting
• /
• v.33 no.3
• /
• pp.1-13
• /
• 2015

Accidents related to gas explosion are frequently happened in foreign countries and in Korea. For the evaluation and the analysis of gas explosions, TNT equivalent methods are used. In this study, the influence of the selection of chemical equation in TNT explosion and the selection of enthalpy of the products on the explosion energy, detonation pressure, velocity of detonation, and temperature was calculated. Depending on the chemical equations, the maximum detonation pressure can be 2 times higher than the minimum. As an example for applying TNT equivalent method, an explosion of methane gas in a confined volume was assumed. With the TNT equivalent, it was possible to predict the variation of peak overpressure and impulse with the distance from the explosion location.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.2
• /
• pp.475-483
• /
• 1993

A computer simulation model of a hermetic reciprocating type of refrigeration compressor has been developed. The compressor simulation model constitutes 6 control volumes, to each of which conservation laws of mass and energy are applied to yield full description of the refrigerant state along its passage. Instead of ideal gas assumption. real gas equation is employed. Some of valve-related input data required for the simulation are acquired from test bench experiments. The refrigerant states such as pressure and temperature, etc., mass flow rates, and valve motions can be predicted by the simulation. The calculated P-V diagram shows a good agreement with experimental result.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.10a
• /
• pp.190-194
• /
• 2007

The forging process design and microstructure evolution for gas turbine disk of a Waspaloy is investigated in this study. Parameters related to deformation are die and preform geometry, and forging temperature of die and workpiece. Die and preform design are considered to reduce the forging load, and to avoid the forging defects. Blocker and finisher dies for multistage forging are designed and the initial billet geometry is determined. The control of hot forging parameters such as strain, strain rate and temperature also is important because the microstructure change in hot working affects the mechanical properties. The dynamic recrystallization evolution has been studied in the temperature range 900-$1200^{\circ}C$ and strain rate range 0.01-1.0s-1 using hot compression tests. Modeling equations are required represent the flow curve, recrystallized grain size, recrystallized volume fraction by various tests. In this study, we used to thermo-viscoplastic finite element modeling equation of DEFORM-2D to predict the microstructure change evolution during thermo-mechanical processing. The microstructure is updated during the entire thermal and deformation processes in forging.

• Transactions of The Korea Fluid Power Systems Society
• /
• v.3 no.4
• /
• pp.8-13
• /
• 2006

The high pressure cryogenic ball valve is used to transfer the liquefied natural gas which temperature is $-196^{\circ}C$, supplied pressure is $168kgf/cm^2$. In the present work, the temperature distribution and thermal deformation is calculated numerically. The CAR and CFD methods are useful to predict the thermal matter and the inner flow field of high pressure cryogenic ball valve. For this reason, to optimum design of the cryogenic ball valve, the theological behavior of the supplied LNG in a cryogenic valve has been studied. The governing equations are discredited and solved numerically by the finite-volume method and finite-element method. In this study, we designed the high pressure cryogenic ball valve that accomplishes zero leakage by elastic seal at normal temperature and metal seal at high temperature.

• Tribology and Lubricants
• /
• v.11 no.5
• /
• pp.108-113
• /
• 1995

Wear and friction behavior of plasma-sprayed coatings in Mo- and Co-based alloy were studied for the application of piston-ring automobile engine. The plasma-sprayed coatings were varied with gun current density, gas flow, and distance. The surface roughness, microhardness, and wear volume were measured depending on the spray distances. The high temperature hardness value were also measured as a function of temperature. Ball-on-disc geometry configuration tribometer was utilized in air. The wear tests were performed in the temperature ranges from room temperature to 825$^{\circ}$C to investigate the tribological trend of the piston-ring materials in the lack of lubricant. The cross sections of wear track were investigated, using microscopy.