• Journal of Korean Society for Atmospheric Environment
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• v.28 no.4
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• pp.384-395
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• 2012

This study was performed to develop the source profiles for fine particles ($PM_{2.5}$) emitted from the biomass burning. The multi-method research strategy included a usage of combustion devices such as field burning, fireplace, and residential wood burning to burn rice straw, fallen leaves, pine tree, and oak tree. The data were collected from multiple sources and measured water-soluble ions, elements, elemental carbon (EC), and organic carbon (OC). From this study, it turned out that OC (34~67%) and EC (1.2~39%) are the major components emitted from biomass burning. In the case of burning rice straw at field burning, OC (66.6%) was the most abundant species, followed by EC (4.3%), $Cl^-$ (3.6%), Cl (2.1%), and $SO^{2-}_4$(1.9%). Burning rice straw, fallen leaves, pine tree, and oak tree at fireplace, the amount of OC was 58.5%, 52.7%, 52.5%, and 61.2%, and that of EC was 1.2%, 18.4%, 36.5%, and 2.7%, respectively. The ratio of OC for the burning of pine tree and oak tree from the residential wood burning device was 56.9% and 34.3%, and that of EC was 25% and 38.6%, respectively. Applying the measured data with respect to the proportion of components emitted from biomass burning to reference model, it turned out that self-diagnosed result was appropriate level, and the result based on the model is in highly corresponding to actual timing of biomass burning.

• Journal of Mechanical Science and Technology
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• v.16 no.12
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• pp.1702-1709
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• 2002

This paper analyzes heterogeneous distribution of branch-like structure at the downstream region of the spray. The liquid and vapor phase of the spray are obtained using a 35㎜ still camera and CCD camera in order to investigate spray structure of evaporating diesel spray. There have been many studies conducted on diesel spray structure but have yet only focused on the analyses of 2-D structure. There are a few information which is concerned with 3-D structure analysis of evaporating spray. The heterogeneous distribution of droplets in inner spray affects the mixture formation of diesel spray and the combustion characteristics of the diesel engines. In this study, the laser beam of 2-D plane was used in order to investigate 3-D structure of evaporating spray The incident laser beam was offset on the central axis of the spray. From the analysis of images taken by offset laser beam, we will examine the formation mechanism of heterogeneous distribution of the diesel spray by vortex flow at the downstream of the spray. The images of liquid and vapor phase of free spray are simultaneously taken through an exciplex fluorescence method. Through this, the branch-like structure consisting of heterogeneous distribution of the droplets forms high concentrated vapor phase at the periphery of droplets and at the spray tip.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.2
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• pp.289-295
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• 1998

Used gasoline engine oils(UGEO) are carcinogenic in long term studies and capable of increasing the number of carcinogen-DNA adducts in short term studies when dermally applied to mice. The carcinogenic risk of UGEO has been attributed to the concentration of polycyclic aromatic hydrocarbons(PAH) which accumulate in the lubricating system during the combustion of gasoline. When dermally exposed to UGEO, the use of hand cleanser was commonly recommended for removing it. But generally workers who dermally exposed oils, use kerosene as cleaner which make skin trouble. During this study, female mice aged 4-6 weeks were utilized to evaluate the efficiency of kerosene, as solvent-based cleanser, following dermal exposure to UGEO. DNA adduct were detected at skin and lung tissues by using the $^{32}P$-postlabeling method. Washing with cleansers were done at two different interval times following dermal application of UGEO. The total DNA adducts in skin and lung tissues were statistically significantly increased in positive control groups, and of which the total adduct level in skin tissues was statistically significant higher than those in lung tissues(p=0.005). When washing kerosene, the DNA adduct level in skin tissues was statistically significantly decreased(p=0.0001). But DNA adducts in lung tissue was statistically increased(p=0.0039), and that washed at 8hr post exposure was more severly increase(p<0.05). The slope of regression between DNA adducts of lung between skin tissues was 1.0802. In conclusion, skin cleaning with kerosene facilitates passage of carcinogens to the lungs of animals dermally treated with used gasoline engine oils(UGEO).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3647-3653
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• 2010

An experimental investigation of the flame appearance and heat transfer characteristics in both unexcited and excited impinging inverse diffusion flames with a loud speaker has been performed. The flame is found to become broader and shorter (in length) with acoustic excitation. The heat flux at the stagnation point is increased with the acoustic excitation. The acoustic excitation is more effective in lean conditions than in rich conditions. The reasons for these behaviors are that acoustic excitation improves the entrainment of surrounding air into the jet. From this study, it is found that the maximum increase of 57% in the total heat flux is obtained at the stagnation point of $\Phi$=0.8. Therefore, it is ascertained that the excitation combustion can be adopted with effective instruments as a method for improving heat transfer in impinging jet flames.

• Journal of the Korean Institute of Gas
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• v.7 no.3 s.20
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• pp.44-50
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• 2003

The axisymmetric methane-air counterflow flame was simulated to investigate changes in the flame structure due to the fuel concentration and to evaluate the numerical method. The global strain rates $a_g=20,\;60,\;90\;s^{-1}$ and the mole fractions of methane $x_m=20,\;50,\;80\%$ in the fuel stream were taken to be numerical parameters. The axisymmetric simulation was conducted by using the Fire Dynamics Simulator (FDS) which employed a mixture fraction combustion model, and the results were compared with those of OPPDIF, which is an one-dimensional flamelet code and includes detail chemical reactions. In all the cases tested, there was good agreement in the temperature and axial velocity profiles between the axisymmetric and one-dimensional simulations. It was shown that the flame thickness and peak flame temperature increase and the flame radius decreases as the fuel concentration increases.

• 대한공업교육학회지
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• v.32 no.2
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• pp.188-198
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• 2007

Platinum nanoparticles loading on carbon nanotube was carried out by impregnation of hexachloro platinate(IV) from hydrogen hexachloro platinate(IV) hydrate dissolved solution without using reduction agents, and heating the hexachloro platinate(IV) impregnated carbon nanotube up to $400^{\circ}C$. The amounts of impregnated hexachloro platinate(IV) on to carbon nanotube were measured with UV-visible spectrophotometer. The TG, XRD, and TEM analysis were performed to confirm the platinum particles loading and distribution on carbon nanotube. The average platinum particles size on carbon nanotube was under 2 nm by heating the hexachloro platinate(IV) up to $400^{\circ}C$ in spite of non-using reduction agents, while the average size increased due to the agglomeration of some particles by heating them up to $800^{\circ}C$. Therefore, uniformly distributed platinum nanoparticles loading on carbon nanotube can be obtained from simple impregnation of hexachloro platinate(IV) from solution and heating it up to $400^{\circ}C$.

• Journal of the Korean Society of Safety
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• v.14 no.3
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• pp.101-109
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• 1999

This study attempts to analyse the solid mixing in the feeder and the packing effect for pressure fluctuations in the fluidized bed. To study the mixing characteristics of solid in vibrating feeder for the stable operations of fluidized combustion, the system consisted of two groups of particles such that fine particles were located on the top of the coarse particles before vibratory mixing had started. The effects of packing materials on the pressure fluctuations in a fluidized bed were analysed by using a statistical method to interpret the behavior of fluidized bed. The experiments were carried out in a fluidized bed of 6.7cm-ID, and the experimental variables were particle sizes, of 115 to 1,015$\mu\textrm{m}$ in diameter and the multi-sized particles haying Rosin-Rammler and Gaussian distributions. The settled bed heights of particles to diameter ratios (L/D) were ranged from 0.5 to 2.0. And fluidizing of particles was carried out by air. The packing materials used were screen packing, and the properties of the pressure fluctuations in the fluidized bed were measured by a differential pressure transducer. The properties of the pressure fluctuations calculated were the mean, the standard deviation, and the major frequency of the power spectral density functions. From the characteristics of fluidizing, it was found that the standard deviation of pressure fluctuations could be effectively used to explain the fluidized phenomena, and the packing materials affected severely the properties of the pressure fluctuations. As a result, from the interpretation by spectral analysis, the effects of measuring radius of pressure fluctuations on standard deviation were constant in the case of the fluidized bed with and without packing materials. However, the effects of measuring the height of pressure fluctuations on standard deviations were linear increasing for the fluidized bed with packing materials, but were constant for the fluidized bed without packing materials at 4.5cm above the gas distributor. The major frequency of pressure fluctuations was found to be nearly independent of fluidized system. Also, the major frequency of pressure fluctuations decreased with increasing packing size, and it had maximum value at 10% of the packing amount.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.176-181
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• 2009

In this work, a new type of DSCs based on nanoporous FTO structure is being developed for research aimed at low-cost high-efficiency solar cell application. The nanoporous FTO materials have been prepared through the sol-gel combustion method followed by thermal treatment at $450{\sim}850[^{\circ}C]$. The properties of the nanoporous FTO materials were investigated by IR spectra, BET and TEM analyses, and the photovoltaic performance of the prepared DSCs were examined. It can be seen from the result that the nanoporous FTO exhibited good transparent conductive properties, well suited for DSCs application.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.148-154
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• 2018

When shooting small arms, the inner surface temperature is heated up to about $700{\sim}1,000^{\circ}C$ by the friction of the bullet and the inner wall of the barrel and the combustion of propellant. High-temperature propellant gas and high-speed movement of the bullet cause corrosion of the inner wall, which is noticeable immediately in front of the chamber. In this study, the mechanical properties of Cr-Mo-V steel, which is the base material, were tested using Taguchi experimental design to find the best nitriding treatment conditions. For the nitriding process, the working time, salt bath temperature, and salt concentration were combined as three conditions and placed in the $L_9(3^4)$, orthogonal array table. The thicknesses of the white layer and the nitrogen diffusion layer were measured after nitriding under each condition in a salt bath furnace. Durability was evaluated by measuring the degree of dispersion through actual shooting because it was difficult to evaluate the mechanical properties of the cylinder inner structure. As a result, it was confirmed that the durability was optimal at $565^{\circ}C$, 1 hour, 0.5%. These optimal conditions were selected by the statistical analysis of the Minitab program(ver.17).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.11
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• pp.1548-1562
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• 2003

This paper is the first of several companion papers which compare the methods of Air-fuel ratio determination. There are many methods which calculate Air-Fuel ratio from exhaust emission. Most of them are based on the simple chemical equations, which use balance of atom, and the error of the calculation is negligible as far as the instrumentation accuracy is guaranteed. They assume homogeneous mixture and complete combustion to the extent of oxygen availability. Because of these simple assumptions, they cannot offer the information about the fuel distribution state and the malfunction of instrument. For these limitations, Eltinge offered new one based on stricter mathematical model. This result coincides with the others very well and gives more information about the mixture state and instrumentation. Consequently this might be a general solution for Air-fuel ratio determination and exhaust composition. The objects of the calculation, however, were not commercial fuels except gasoline and the compensation method of unburned hydrocarbon was not appropriate to recent analyzer. Moreover he did not consider the fuel which contains oxygen, such as methanol, ethanol and blend of gasoline-alcohol. In this paper, Eltinge chart is expanded to the arbitrary fuel composition as the reference exhaust compositions for the purpose of further discussions about Air-fuel ratio determination methods and the charts fur gasoline, diesel, methanol, M85, liquefied petroleum gas(LPG), natural gas(NG), propane, butane are illustrated.