• International Journal of Automotive Technology
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• v.6 no.2
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• pp.79-85
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• 2005

This work is to investigate the surface heat flux and combustion characteristics of premixed propane mixture in a constant volume chamber. The experiment of heat flux and combustion characteristics of premixed propane mixture are performed with various equivalence ratio and initial pressure conditions. Based on the experimental results, it is found that the maximum instantaneous temperature is increased with the increase of initial pressure in the chamber. There are significant differences in the burning velocity of premixed propane mixture at different measuring points in the constant volume combustion chamber. A]so, the trends of temperature difference at each measuring points are similar to the burning velocity in the combustion chamber. It is concluded that the total heat loss during the combustion period is affected by the equivalence ratio and the initial condition of fuel-air mixture.

• Journal of Radiation Protection and Research
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• v.36 no.2
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• pp.59-63
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• 2011

It is important to reduce indirect scattered neutron beside direct neutron of chosen energy for designing a neutron-reference-field laboratory with neutron produced from a nuclear reaction by a accelerator. Therefore MCNPX simulation was performed with various conditions for obtaining such condition. At first in the original laboratory condition we calculated the direct neutron flux which was inserted in chamber (virtual chamber composed of air) of 0 degree (proton moving direction) for neutron flux measurement and the scattered neutron flux which is inserted in the chamber after scattering wall or bottom. In the result, the scattered neutron which was inserted after scattering bottom is more than that which was inserted after scattering the others. Therefore MCNPX simulation was again performed with removing the concrete bottom and with removing the concrete bottom and digging 1 m in the ground. In the result of removing concrete bottom and digging 1 m in the ground, scattered neutron which was inserted after scattering bottom became less than that which was inserted after scattering the others.

• Journal of the Korean Society for Heat Treatment
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• v.16 no.4
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• pp.216-223
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• 2003

In the production of internal combustion engines, there have been trends to develop the high performance engines with improved fuel efficiency, lighter weights and smaller sizes. This trends help to answer problems related to thermal load and abnormal combustion, etc. in these engines. In order to investigate these problems, a thin film-type probe and its manufacturing method for instantaneously measuring surface-temperatures have been proposed in this study, Instantaneous surface temperature of a constant volume combustion chamber was measured by this probe and heat flux was obtained by Fourier analysis. In order to thoroughly understand the characteristics of combustion, the authors measured the wall temperature of the combustion chamber and computed heat flux through a cylinder wall while varying the protrusion height of the probe have been measured. To achieve the above goals, a instantaneous temperature probe was developed, thereby making possible the analysis of the instantaneous temperature of wall surface and the detection of unsteady heat flux in the constant volume combustion chamber.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.4
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• pp.1-6
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• 2002

A numerical heat transfer analysis and the structural analysis were performed for the design of sub-scale combustion chamber's coolant passage. The heat flux through the combustion chamber wall was estimated by 2-D heat transfer analysis of compressible hot gas and the result was applied as a thermal boundary condition of 3-D analysis. The heat flux estimated by the present method agreed well with the experimental correlation and proved to be insensitive to cooling condition. So the same thermal boundary condition was applied for various operating conditions. The maximum temperature of combustion chamber wall was predicted by 3-D analysis for single coolant passage and the result will be used for the development of a regeneratively cooled combustion chamber. Also estimated were the stress distribution and structural safety of coolant passage through the static structural analysis.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.3
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• pp.170-178
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• 2007

Rapid increases in the concentrations of greenhouse gases and many other chemically important trace gases have occurred over the last several centuries. For understanding the roles of these important gases in global change, it is essential to identify their sources and sinks, to characterize biogenic gas fluxes between the biosphere and atmosphere, and to understand the processes that control them. In this paper, enclosure-based measurements are described in a practical manner for field experiments. Theoretical reviews of mass balance equation in the enclosure and sensitivity of the flow-through dynamic flux chamber technique are presented; specifically for the case of NO flux measurements from soil surface. The physical system and theory behind the flow-through dynamic flux chamber method are examined. New calculation flux formula was introduced by considering NO chemical loss on chamber wall and uncertainties of the NO flux calculation were discussed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.243-246
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• 2008

The combustion characteristic of solid fuel with chamber pressure were experimentally studied in hybrid combustion. This paper was experimental confirmed whether solid fuel affected not only oxidizer mass flux but also chamber pressure. Poly-Ethylene(PE) was used as fuel, GOX was used as oxidizer. Chamber pressure was controled by nozzle throat diameter 6mm and 9mm. In low oxidizer mass flux, solid fuel regression rate was affected not only oxidizer mass flux but also chamber pressure. As well, the regression rate increase as chamber pressure increase with same oxidizer mass flux.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.6
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• pp.749-758
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• 2004

Nitrous oxide ($N_2$O) has been known as an important trace gas due to the greenhouse gas and the major source of stratospheric oxide of nitrogen (NO). Soil is the major source of $N_2$O in nature. The physicochemical characteristics of soils affect the emission of $N_2$O from soil. These physicochemical parameters are soil moisture, soil temperature, and soil N content. Since these parameters are correlated to the flux of $N_2$O from soil individually and compositely, there still remain many unknowns in the mechanism to produce $N_2$O in soil and the roles of such physicochemical parameters which affect the soil $N_2$O emission. Soil $N_2$O fluxes were measured at different levels in water filled pore space (WFPS), soil temperature and soil N contents from the same amounts of soils which were sampled from agriculturally managed upland field in a depth of ～30 cm at Kunsan. The soil $N_2$O flux measurements were conducted in a laboratory with a closed flux chamber system. The optimum soil moisture and soil temperature were observed at 60% of WFPS and ～13$^{\circ}C$. The soil $N_2$O flux increased as soil N contents increases during the whole experimental hours (up to 48 hours). However, average $N_2$O flux decreased after ～30 hours when organic carbon was mixed with nitrogen in the sample soils. It is suggested that organic carbon could be important for the emission of $N_2$O, and that the ratio of N to C needs to be identified in the process of $N_2$O soil emission.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.178-187
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• 1997

For the experimental measurement of heat flux of DI diesel engine combustion chamber, the instantaneous temperature probes and data acquisition system were developed. By the analysis of measured temperatures at the cylinder head, the temperature at the point 3 which is located between intake and exhaust valve was higher than that of the other points. Temperatures at the point located mear the exhaust valve were higher than those of intake valve. The instantaneous and mean temperature at the cylinder head increases proportionally to the increase of the engine speed, while the temperature swing varies inversely. Temperature swings have influence on the maximum heat flux values from gas into head surface. It has been verified that these probes and data acquisition system perform well by the comparison of the trend of instantaneous temperature variation with that of measured combustion chamber pressure variation with respect to crank angle. It is presumed that these probes could be used in the measurement of other parts of combustion chamber as piston, cylinder wall etc. for the future study.

• Journal of the Korean Society of Visualization
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• v.10 no.3
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• pp.25-29
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• 2012

This paper introduces a new parameter to design the $2{\times}2$ microfluidic centrifuge with single flow rotation positioned at the center of microchamber. The dimensional centrifugal acceleration momentum flux which is defined as the interfacial momentum flux divided by distance from the center of the chamber explains the flow rotation and its threshold provides a reference to expect single flow rotation. Through the numerical and experimental visualization of the flow rotation, the number and position of flow rotation in the $2{\times}2$ microfluidic centrifuge were examined. At a channel width of $50{\mu}m$ and chamber width of $250{\mu}m$, single flow rotation was obtained over at a Reynolds number of 300, while at a channel width of $100{\mu}m$ and chamber width of $500{\mu}m$, single flow rotation did not appear. The numerical analysis showed that the threshold centrifugal acceleration momentum flux to obtain single flow rotation was $3500kg/m{\cdot}s^2$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.1
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• pp.60-67
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• 2000

An experimental investigation on transient heat transfer phenomena of impinging diesel-spray on a flat plate in a pressurized chamber is carried out. A diesel spray is injected from a single-hole nozzle and impinges to a heated flat plate in the chamber. A fast-response thermocouple installed in the top surface of the plate measures the transient variation of surface temperature of the plate under various conditions of the chamber pressures. Utilizing the semi-infinite model, the temporal variation of the heat flux on the plate is determined. Effects of various parameters, such as vertical distances between the nozzle and the plate, radial distances from the injection-axis, and the chamber pressures, on the heat flux characteristics of impinging diesel-spray are studied.