• Journal of Environmental Science International
• /
• v.15 no.12
• /
• pp.1087-1091
• /
• 2006

This paper describes the current spatial patterns of the net primary productivity (NPP) of the terrestrial vegetation and carbon emission (C) in the world due to the burning of fossil fuels in order to clarify the amount of expansion of human activity. The C/NPP value varies spatially from almost zero to several tens of thousand times the local NPP. C/NPP is higher under the condition of extensive human activities due to a high human population density or when the local NPP is extremely low in severe climatic zones. In contrast, the low C/NPP areas are distributed mainly in sparsely populated districts, loading to a low impact of human activity. Although the area where C/NPP is less than 10% accounts for about 70% of the entire land area, one-third of these areas cannot contribute to carbon absorption because of low NPP with a shortage of climatic resources. Since more than half of the areas of the remaining areas are agricultural land and forest ecosystems with high NPP, the possible afforestation area was evaluated to be maximum of $30{\times}10^{6}\;km^{2}$; here only sequestrate carbons that correspond to 2% of the global total NPP are present. These analyses revealed that presently most of the areas where the NPP is high are those exclusively used by humans and that it is difficult for large-scale forest plantations to absorb a substantial amount of the carbon emitted annually by humans.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.881-885
• /
• 2004

We report a method for making a device on which semi-conducting single-walled carbon nanotubes are attached selectively between two metal electrodes. This method is divided two processes. First we can connect a rope of single-walled carbon nanotubes(SWNTs) between two electrodes using the electric field. But a SWNTs' rope obtained by the first process was composed of a few of metallic and semi-conducting SWNTs together. The second process is to burn the metallic and semi-conducting nanotubes through applying a voltage. As a result, we can obtain a semi-conducting SWNT device. To make the patterned electrodes, we deposited $SiO_2$(150nm) on a wafer. After then, we made a patterned samples with Ti(200 $\AA$)/Au(300$\AA$). We empirically obtained a electric condition 0.66 $V_{pp}$ /${\mu}{\textrm}{m}$@5MHz. From this result, we verified that most of current go through the metallic nanotubes in this device. When we apply DC voltage between two electrodes, the metallic carbon nanotubes are burnt. Finally, we can obtain a semi-conducting nanotube device which we desire to make. We got the I-V characteristic graph which has shown the semi-conducting property. We hope to apply to the various applications using this selective semi-conducting carbon nanotube deposition method.ethod.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.4
• /
• pp.518-524
• /
• 1997

Experimental studies on combustion phenomena within a porous ceramic burner are reported. Main interest of the present work is to investigate fundamental flame behaviors and their effects on the burner operation. Due to high thermal capacity of the porous ceramic materials, the response of flame to burning condition changes is slow and thus to have a stabilized flame is quite difficult and takes much time. It is found that the temperature profile obtained at downstream of the flame zone is not much sensitive to the movement of flame and the speed of flame movement is less than 0.1 mm/sec for the conditions tested. With the premixed LPG/air flame imbedded within the porous ceramic burner, stable combustion regions and unstable combustion regions leading to blowoff or flashback phenomena are observed and mapped on flow velocity versus equivalence ratio diagram. For the development of burner operation technique which is more practical and safe, intermittent burning technique, where the fuel or/and air is supplied to the burner intermittently, is proposed as one of the flame control methods for the porous ceramic burner and tested in this study. Through the experiment, it is realized that the proposed method is acceptable in respect to burner performance and give much flexibility in the operation of porous ceramic burner.

• Nuclear Engineering and Technology
• /
• v.33 no.1
• /
• pp.83-92
• /
• 2001

The properties of off-gas generated from vitrification process of ion-exchange resin were characterized. Theoretical composition and flow rate of the off-gas were calculated based on chemical composition of resin and it＇s burning condition inside CCM. The calculated off-gas flow rate was 67.9Nm$^3$/h at the burning rate of 40kg/h. And the composition of off-gas was avaluated as $CO_2$(41.4%), steam(40.0%), $O_2$(13.3%), NO(3.6%), and SO$_2$(1.6%) in order. Then, actual flow rate and composition of off-gas were measured during pilot-scale demonstration tests and the results were compared with theoretical values. The actual flow rate of off-gas was about 1.6 times higher than theoretical one. The difference between theoretical and actual flow rates was caused by the in-leakage of air to the system, and the in-leakage rate was evaluated as 36.3Nm$^3$/h. Because of continuous change in the combustion parameters inside CCM, during demonstration tests, the concentration of toxic gases showed wide fluctuation. However, the concentration of CO, a barometer of incompleteness of combustion inside CCM, was stabilized soon. The result showed quasi-equilibrium state was achieved two hours after feeding of resin.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.05a
• /
• pp.138-141
• /
• 2010

A study to reduce the ignition peak pressure of gas generator for the missile launching system was accomplished. The igniter, as the energy release device for igniting the propellant, is aimed at simultaneous ignition of bundled 3-layered propellant grain without unstable burning. In case of our gas generator which must use the double-base propellant with low ignition property, the fast ignition of propellant and reduction of initial peak pressure should be required for the satisfaction of ejection velocity and acceleration condition. By applying MTV ignition charge for the igniter of gas generator, we accomplished all system performance requirements.

• International Journal of Aeronautical and Space Sciences
• /
• v.16 no.2
• /
• pp.247-253
• /
• 2015

The components of an aero-engine gas path cannot be monitored in a timely way due to a lack of real-time monitoring technologies. As an attempt to address this problem, we have conducted research on a condition monitoring technology based on the charging characteristics of particles in an aero-engine gas path, and emphatically analyze the formation of particles in an aero-engine gas path, the charging mechanism of carbon particles and the factors that influence the charge quantity and polarity. The verification experiments are performed on the simulated experiment platform and a turbo-shaft engine test bench. The results show the carbon particles' carry charge, and an obvious change in the total electrostatic charge level in the aero-engine gas path due to the increased carbon particles produced by burning or abnormal metal particles; the charge number is related to the size of particles, and the bigger carbon particles carry a negative charge and metal particles carry a positive charge; the change in engine power can lead to an obvious change in the level of electrostatic charge in the gas path, and the change in electrostatic charge results from the extra carbon particles formed in the rich-oil burning process. The research provides a reference for establishing the baseline of electrostatic charge while the engine runs on different power. The study also demonstrates the validity of the electrostatic monitoring technology and establishes a base for developing the application of electrostatic monitoring technology in aero-engines.

• Journal of the Korean Society of Tobacco Science
• /
• v.26 no.2 s.52
• /
• pp.141-151
• /
• 2004

This study was conducted to evaluate the characterization of the pyrolysis products of tobacco constituents such as cellulose, lignin and tobacco additives. The pyrolysis condition was designed to simulate the pyrolysis/distillation zone$(200\~600^{\circ}C)$ and combustion zone$(700\~950^{\circ}C)$of burning com in the smoking cigarette. The pyrolysis products were determined by GC/MS after pyrolysis using Double-Shot pyrolyzer. In the case of cellulose and lignin, the number of pyrolysis product in the condition that simulate the pyrolysis/distillation zone was much more than the combustion zone simulating one. The major products of cellulose were levoglucosan, furfural, and 1, 6-anhydro-$\beta$-D-glucofuranose and that of lignin were phenol, 2-methoxy phenol, and 1, 2-dimethoxy benzene. In the case of tobacco additives such as 2, 6-dimethyl pyrazine, maltol, and piperonal, the pyrolysis products of these additives were evaporated from the pyrolyszer at least $96\%$ intactly. These results indicate that tobacco constituents such as cellulose and lignin were thermally degraded at the pyrolysis/distillation zone and thoroughly broke down at the combustion zone, but tobacco additives were intactly evaporated from burning com of smoking cigarette.

• Journal of Oral Medicine and Pain
• /
• v.42 no.3
• /
• pp.81-84
• /
• 2017

Oral submucous fibrosis (OSF) is a premalignant condition characterized by juxtaepithelial fibrosis of the oral cavity. The clinical manifestations include burning sensation to spicy food, blanched oral mucosa with palpable fibrous bands, trismus, depapillation of tongue, and dry mouth. As OSF is predominantly seen in people of the Indian subcontinent, cases of this disease have been rarely reported in South Korea. We present a case of OSF in a Sri Lankan man living in South Korea and emphasize the importance of enhancing knowledge of this disease while the number of immigrants is increasing.

• Journal of the Korean Applied Science and Technology
• /
• v.23 no.4
• /
• pp.362-367
• /
• 2006

This paper describes the experiments for investigating the effects of thermal stability of several commercial carpet mate materials. The melting point and thermal decomposition temperature was measured by means of a differential scanning calorimeter(DSC) in air condition. The DSC data and burning test results of nylon bulked continuous filament(N-BCF) yarn 100%, nylon(NY), polypropylene(PP), and a new material named polytrimethyleneterephthalate(PTT) were analysed to obtain the effect on their thermal stability. Conclusively, we observed that PTT and PP were approximately $380^{\circ}C$ and $240^{\circ}C$ to start the thermal decomposition, respectively. In other words, PTT is thermally the most stable material for carpet manufacturing.

• Journal of the Korean institute of surface engineering
• /
• v.36 no.2
• /
• pp.176-184
• /
• 2003

New lubricant film of organic and inorganic composite resin was developed to improve the press formability of galvannealed steel sheets (GA) for automotive body panels. The frictional coefficient of lubricant GA steel sheets is about 20% superior to that of uncoated GA. The current range of spot welding of lubricant GA is similar to that of the uncoated GA, but the burning trace of spot welding is inferior to that of the uncoated GA in the oiling condition. The alkaline degreasability of lubricant GA shows 100% in alkaline degreasing condition of automotive company. The size and shape of the phosphated coating layer are similar to those of the uncoated GA sheet. The powdering property of the lubricant GA gives rise to 20∼50% improved property compared with the uncoated GA sheet.