• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.350-350
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• 2011

The spin structure of Fe over layers on Cu (001), especially in region II is one of the unsolved problem for many years. We study the out - of - plane (OP) Fermi surfaces (FSs) of 7 monolayer Fe/Cu (001) films using angle resolved photo emission spectroscopy (ARPES). Ultrathin Fe was grown on Cu (001) substrate at room temperature and the experimental measurements were carried out at room temperature and low temperature. Fermi surfaces measured about $\frac{1}{4}$ of the Brillouin Zone (BZ) using photon energies ranging from 170 eV to 280 eV. Our results confirmed that ferromagnetic signal at 7 ML Fe on Cu (001) is nearly zero. These results are consistent with our recent x-ray magnetic circular dichroism (XMCD) and surface magneto - optic Kerr effect (SMOKE) experiments. Based on our observations we have made a simple model of this system, which explains all the experimental results.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.35-42
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• 2001

The diesel engine exhaust gas is know as one of the causes to produce photochemical smog, which causes damage on environmental. However, due to the high thermal efficiency and low carbon dioxide emission, the usage of a diesel engine is prevailed. In this study, the DC non-thermal plasma technology used to the particulate matter (PM) aftertreatment. The exhaust gas characteristics and energy density were investigated on the dynamometer test bed and chassis dynamometer with CVS-75 mode in a passenger diesel car. It was reported that the smoke removal efficiency has around the 70% in the dynamometer test with 80W energy consumption and the PM removal efficiency has the 68% in the real car test. The NOx also reduced the 20% according to electrode type respectively. Considering these results, plasma technology is one of the ways to simultaneously removing method the particulate matter (PM) and NOx.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.1-11
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• 2000

This study is aimed to develop a proto-type LPG engine for medium-duty commercial vehicles in order to substitute for conventional diesel engine. Recently, it is recognized that diesel engines are main cause for smoke pollution in urban site. So, it is expected to reduce this environmental emission by developing and substituting LPG engine which has the advantage of practical use in a short development period in aspects of infrastructures. For that, after analysing the specifications and performance characteristics of a base diesel engine, parts of combustion chamber, intake system, fuel supply and ignition systems suitable for LPG combustion were re-designed and manufactured. And and engine controller for fuel supply and ignition distributions was matched by feedback mapping based on the speed-load conditions. The torque and power of LPG engine were increased by 6∼12% on the overall driving conditions compared to the base diesel engine, and fuel consumption rate marked the similar level based on the fuel price. Exhaust emissions such as THC, CO, NOx recorded the same order with conventional LPG engine for passenger car.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.138-143
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• 2006

Modification of injector, oil ring tension reduction and oil pump rotor re-matching with optimization of relevant engine control parameters could drive fuel consumption reduction of HSDI diesel engine. A 5 holes injector was replaced with a 6 holes with smaller nozzle hole diameter and 1.5 k factor, and evaluated in a view of fuel economy and emission trade-offs. With introducing smaller nozzle hole diameter injector, PM(Particulate Matter) was drastically decreased for low engine load and low engine rpm. Modification of oil pump and oil ring was to reduce mechanical friction and be proved to better fuel economy. Optimization of engine operating conditions was a great help for the low fuel consumption. Influence of the engine operating parameters· including pilot quantity, pilot interval, air mass and main injection timing on fuel economy, smoke and NOx has been evaluated with 14 points extracted from NEDC(New European Driving Cycle) cycle. The fuel consumption was proved to $7\%$ improvement on an engine bench and $3.7\%$ with a vehicle.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.4
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• pp.459-469
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• 2005

In recent years, concerns have been growing globally regarding greenhouse gases. Open burning of biomass causes emission of a number of greenhouse and other gases and substances. This paper studied an analysis on the characteristics of four types of biomass using duel type cone calorimeter. Cone calorimeter is widely used for assessing combustibility of materials in Europe. As a result, we evaluated several characteristics of biomass, such as heat released rate, smoke production rate, CO, $CO_2$ production and mass loss rate, and so on. $CO_2$ is currently responsible for over $60\%$ of the enhanced greenhouse effect, and may be the most important contributor to future. $CO_2$ production for biomass in the range of $1.74\~1.99kg/kg$ is similar to previous research conducted by Bhattacharya et al. (2002a).

• Fire Science and Engineering
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• v.32 no.2
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• pp.30-37
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• 2018

This study is an analysis of combustion characteristics of synthetic insulation materials such as houses and warehouses. Using combustion cone calorimeter and SEM, the researching has experimented combustion characteristics of four kinds of materials such as flame retardant styrofoam, general styrofoam, urethane and gypsum board. And analyzed. As a result of the test, the ignition time (TTI) for the thermal insulation material was found at 27 s~43 s, and the flame retardant styrofoam was ignited at the lowest TTI at 27 s and disappears at 28 s. In addition, the maximum heat release rate (peak HRR) and average heat release rate (mean HRR) of each material were expressed in the following order: urethane> flame retardant styrofoam> styrofoam> gypsum board. Also, the total smoke release ($m^2/m^2$) was the largest at $30.798m^2/m^2$ in flame-retardant styrofoam. The general CO concentration of styrofoam was 0.275 kg/kg and the emission concentration was 12.807 kg/kg. The residues showed the highest 0.029 g in the gypsum board among the above materials.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.445-449
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• 2005

Present study was designed to evaluate the practical application of triethyl amine(TEA) injection for improving the collection efficiency of electrostatic precipitator(ESP) connected to a real operating plant. The major fuels used at the domestic power stations were bituminous coals imported from Australia, China, South Africa, and USA. Although the values of the electric resistance would be more or less different according to the type of the coals used, the unique electric resistance values of fly ash from the coals were mostly higher than $1{\times}10^{12}\;{\Omega}-cm$ and therefore, back corona problems were always expected to occur in the electrostatic precipitator. The particulates concentrations, smoke concentrations and their electric resistivity measured at the outlet of ESP, and the inspection of collection indicated that the injection of TEA improved the collection efficiency of particulate at collection plates of ESP. The electric resistance for, fly ash with the injection concentration of TEA 15 ppm(Purity 99.7%) was lowered to $2.1{\times}10^{11}\;{\Omega}-cm$ after injection from $1.9{\times}10^{12}\;{\Omega}-cm$ before injection. Under this condition, the dust emission content at the stack was reduced to approximately 80%, lowering the average outlet concentrations of particulates from $70\;mg/Sm^3$ to $14\;mg/Sm^3$.

• Fire Science and Engineering
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• v.34 no.1
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• pp.55-65
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• 2020

In this study, the ISO 5660 and ISO 5659 combustion tests were conducted with synthetic resin conduits (CD, VE) and metal conduit (ST) used for wiring work in electrical facilities, which can be installed in ceiling concealed places. Then, fire spreading and evacuation risks were analyzed based on the measured data. In the ISO 5660 test, CD of 120.5 MJ/㎡, VE of 81.9 MJ/㎡, and ST of 4.9 MJ/㎡ were measured. In the ISO 5659 test, the CD 1320, VE 731, and ST 102 were measured, and then the maximum smoke densities were measured for CD 605 s, VE 740 s, and ST 1,200 s. In terms of fire spreading and evacuation risk, the CD conduit, VE conduit, and ST conduit were in order. In the fire spreading risk analysis, total heat emission was calculated as 4,820 MJ/㎡, 4,267 MJ/㎡, and 196 MJ/㎡ for CD, VE, and ST, respectively. Evacuation risk analysis shows at transmittance of 89%, CD is 127 s, VE is 35 s, and ST is 969 s. At transmittance of 79%, representing almost invisible concentration, CD is 157 s and VE is 50 s. The CD and VE conduits had a high fire spreading and evacuation risks, while the ST conduit had little effect on fire spreading and evacuation risk.

• Advances in nano research
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• v.16 no.2
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• pp.127-140
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• 2024

Upon direct/indirect exposure to flame or heat, composite structures may burn or thermally buckle. This issue becomes more important in the natural fiber-based composite structures with higher flammability and lower mechanical properties. The main goal of the present study was to obtain an optimal eco-friendly composite system with low flammability and high thermal buckling resistance. The studied composite consisted of polypropylene (PP) and short abaca fiber (AF) with eggshell powder (ESP) and halloysite clay nanotubes (HNTs) additives. An optimal base composite, consisting of 30 wt.% AF and 70 wt.% PP, abbreviated as OAP, was initially introduced based on burning rate (BR) and the Young's modulus determined by horizontal burning test (HBT) and tensile test, respectively. The effects of adding ESP to the base composite were then investigated with the same experimental tests. The results indicated that though the BR significantly decreased with the increase of ESP content up to 6 wt.%, it had a very destructive influence on the stiffness of the composite. To compensate for the damaging effect of ESP, small amount of HNT was used. The performance of OAP composite with 6 wt.% ESP and 3 wt.% HNT (OAPEH) was explored by conducting HBT, cone calorimeter test (CCT) and tensile test. The experimental results indicated a 9~23 % reduction in almost all flammability parameters such as heat release rate (HRR), total heat released (THR), maximum average rate of heat emission (MARHE), total smoke released (TSR), total smoke production (TSP), and mass loss (ML) during combustion. Furthermore, the combination of 6 wt.% ESP and 3 wt.% HNT reduced the stiffness of OAP to an insignificant amount by maximum 3%. Moreover, the char residue analysis revealed the distinct differences in the formation of char between AF/PP and AF/PP/ESP/HNT composites. Afterward, dilatometry test was carried out to examine the coefficient of thermal expansion (CTE) of OAP and OAPEH samples. The obtained results showed that the CTE of OAPEH composite was about 18% less than that of OAP. Finally, a theoretical model was used based on first-order shear deformation theory (FSDT) to predict the critical bucking temperatures of the OAP and OAPEH composite plates. It was shown that in the absence of mechanical load, the critical buckling temperatures of OAPEH composite plates were higher than those of OAP composites, such that the difference between the buckling temperatures increased with the increase of thickness. On the contrary, the positive effect of CTE reduction on the buckling temperature decreased by raising the axial compressive mechanical load on the composite plates which can be assigned to the reduction of stiffness after the incorporation of ESP. The results of present study generally stated that a suitable combination of AF, PP, ESP, and HNT can result in a relatively optimal and environmentally friendly composite with proper flame and thermal buckling resistance with no significant decline in the stiffness.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1022-1027
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• 2011

A diesel engine works in high compression ratio due to injection of diesel fuel after compression of air. Therefore the engine has a high thermal efficiency, while nitrogen oxide is produced a lot in high flame temperature regions. In order to solve the problem this study HHO gas is added into the intake air of the industrial diesel engine. The test conditions are loads of 0%, 50% and 100% and engine speeds of 700 to 1900 rpm. The results show the maximum torque and pressure is increased, fuel consumption, smoke and CO emissions are decreased and NOx emission is remained at same level.