• Transactions of the Korean hydrogen and new energy society
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• v.29 no.6
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• pp.654-660
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• 2018

The dependence on global fossil fuels has been gradually reducing all over the world. Some countries which recognized the important of environmental values were joining to carry out international GHG goals. Our country has also participated with high targets (37% reduction compared to BAU 2030 years). So we need to supply materials of lower GHG value such as a bio-diesel. Bio-alcohol is one of the similar bio-fuels that can be reducing GHG. A lot of countries had tried to commercialize through various R&D for bio-alcohol. In this study, we analyzed the fuel characteristics of bio-alcohol fuel produced by domestic technology. And we evaluated a possibility to use as vehicle fuel through mixing of bio-alcohol and gasoline. The mixed fuels were satisfied with 2.3 wt% of oxygen content that is standard of the petroleum and petroleum alternative fuel business Act. We tried to evaluate a emission characteristic of vehicle by mixed fuel. In accordance with the results we tried to find a correlation between fuel and emission.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.289-292
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• 2004

In order to identify the origin and nature of the spilled oil in the potential source, we analyzed the pattern of alkyi PAM(Polynuclear Aromatic Hydrocarbons) in fuel standard and environmental samples. Alkyl PAM patterns are used for fuel-type identification in weathered environmental samples. Detection of alkyl PAH was achieved by operation CC/MS in the SIM mode. We chose ions of naphthalene(m/z 128), C1-naphthalene(m/z 142), C2-naphthalene(m/z 156), C3-naphthalene(m/z 170), C4-naphthalene(m/z 184) for the comparison of this pattern according to the type of fuel. We analyzed tile pattern of alkyl PAH in neat gasoline, kerosene, diesel, and JP-8, and in groundwater samples which were collected in monitoring wells. The distribution map of alkyl-naphthalene shows different patterns among four different fuel types (gasoline, kerosene, diesel, and JP-8). Particularly, tile distribution map of kerosene and JP-8 is found to be of value in identifying fuel type in that the difference is clear. Therefore distribution patterns of alkyl-PAH compounds provide another useful tool for fuel-type identification of petroleum fuels.

• Nuclear Engineering and Technology
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• v.43 no.3
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• pp.309-316
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• 2011

Molybdenum is the most abundant fission product since its fission yield is equivalent to that of xenon, and it has a very special role in the chemistry of nuclear fuel because it influences the oxygen potential of $UO_2$ fuel. In this study, the distribution of molybdenum in spent $UO_2$ fuel specimens with 33.3, 41.0 and 57.6 GWd/tU burnup was measured by a LA-ICP-MS system and the reproducibility of the measured data was obtained. The Mo distribution was almost constant along the radius of a fuel except an increase at the periphery of the fuel. It showed a drop in reproducibility with relatively high deviation of measured values for the highest burnup fuel. To explain this, the state of molybdenum in a $UO_2$ matrix and its effect on the oxidation behavior of $UO_2$ were investigated. The low reproducibility was explained by the segregation of molybdenum, and the inhibition of oxidation by the molybdenum was also observed.

• Journal of ILASS-Korea
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• v.6 no.2
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• pp.16-21
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• 2001

This paper describes the macroscopic behavior and atomization characteristics of the high-pressure gasoline swirl injector in direct-injection gasoline engine. The global spray behavior of fuel injector was visualized by shadowgraph technique. The atomization characteristics of gasoline spray such as mean diameter and mean velocity of droplets were measured by the phase Doppler particle analyzer system. The macroscopic visualization and experiment of particle measurement on the fuel spray were investigated at 7 and 10 MPa of injection pressure under different spray cone angle. The results of this work show that the geometry of injector was more dominant over the macroscopic characteristics of spray than the fuel injection pressure and injection duration. As for the atomization characteristics, the increase of injection pressure resulted in the decrease of fuel droplet diameter and the atomization characteristics differed as to the spray cone angle. The most droplets had under $25{\mu}m$ diameter and for the large droplets(upper $40{\mu}m$) as the spray grew the atomization presses were very slow. Comparison results between the measured droplet distribution and the droplet distribution functions revealed that the measured droplet distribution is very closed to the Normal distribution function and Nukiyama-Tanasawa's function.

• Journal of the Korean Applied Science and Technology
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• v.32 no.1
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• pp.136-147
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• 2015

As it carry out RPS(Renewable Portfolio Standards), power producers are using the power bio-fuel oil to meet their RPS quota. In this study, we test the quality characteristics of raw materials for power bio-fuel oil and the property changes of power bio-fuel oil by the kind of feedstocks. The power bio-fuel oil and feedstocks were analyzed for item of quality standard such as acid number, viscosity and metal contents. And it was analyzed for composition distribution by FT-IT and HPLC. Such as low priced palm oil series has high acid number and ash contents due to high free-fatty acid and metal contents. And by-product of biodiesel have a tendency of high viscosity. The fuel properties of power bio-fuel oil, such as viscosity, acid number and metal contents are correlated with the constituent and the mixing ratio of the feedstocks.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.7-12
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• 2003

Mixture formation in the cylinder of a lean bum engine has been observed by Laser Induced Fluorescence technique. XeCl laser (308nm) was used to produce a laser sheet. 3-pentanone has been added to iso-octane fuel to produce fluorescence, the intensity of which is proportional to the concentration of the fuel. The laser sheet was introduced through the piston window and the fuel distribution in the vertical plane was observed through a side window. Comparison has been made for the cases of selected fuel injection timing as 0, 360, 405, and 450 CA. For the case of 0 and 360 CA injection, uniform fuel distribution in the combustion chamber has been obtained at the ignition time which is favorable for the high load mode. And the late injection cases, 405 and 450 CA, revealed the stratified formation of rich mixture around the spark plug. That extends the lean misfire limit and reduces cyclic variation in the low load mode.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2415-2421
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• 2020

The axial heterogeneous void distribution in a fuel channel is a relevant and important issue during nuclear reactor analysis for LWR, especially for boiling water channel-type reactors. Variation of the coolant density in fuel channel has an effect on the neutron spectrum that will in turn have an impact on the values of absolute reactivity, the void reactivity coefficient, and the fuel isotopic compositions during irradiation. This effect is referring to as the history effect in light water reactor calculations. As the void reactivity effect is positive in RBMK type reactors, the underestimation of water density heterogeneity in 3D reactor core numerical calculations could cause an uncertainty during assessment of safe operation of nuclear reactor. Thus, this issue is analysed with different cross-section libraries which were generated with WIMS8 code at different reference water densities. The libraries were applied in single fuel model of the nodal code of QUABOX-CUBBOX/HYCA. The thermohydraulic part of HYCA allowed to simulate axial water distribution along fuel assembly model and to estimate water density history effect for RBMK type fuel.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.1
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• pp.46-54
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• 2021

This study compared and analyzed the effects of forest tending works on the vertical distribution of wildfire fuel loads on Pinus densiflora stands in Gyeongbuk province. The study sites were located in Youngju and Bonghwa in Pinus densiflora stands. A total of 10 sample trees were collected for the development of the crown fuel vertical distribution model. The 6th NFI (National Forest Inventory) selected a sample point that only extracted from managed and unmanaged stands of Pinus densiflora in the Gyeongbuk province. The fitness index (F.I.) of the two models developed was 0.984 to 0.989, with the estimated parameter showing statistical significance (P<0.05). A s a results, the vertical distribution of wildfire fuel loads range of unmanaged stands was from 1m to 11m with the largest distribution at point 5m at the tree height. On the other hand, the vertical distribution of wildfire fuel loads range of the managed stands was from 1m to 15m with the largest distribution at the point of 8m at the tree height. The canopy bulk density was 0.16kg/㎥ for the managed stands and 0.25kg/㎥ for the unmanaged stands, unmanaged stands were about 1.6 times more than managed stands. This result is expected to be available for simulation through the implementation of the 3D model as crown fuel was analyzed in three dimensions.

• Journal of ILASS-Korea
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• v.18 no.2
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• pp.100-105
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• 2013

While variable valve actuation or variable valve lift (VVL) is used increasingly in spark ignition (SI) engines to improve the volumetric efficiency or to reduce the pumping losses, it is necessary to understand the impact of variable valve lift and timing on the in-cylinder gas motions and mixing processes. In this paper, characteristics of the in-cylinder flow and fuel distribution for various valve lifts (4, 6, 8, 10 mm) were simulated in a GDI engine. It is expected that the investigation will be helpful in understanding and improving GDI combustion when a VVL system is used. The CFD results showed that a increased valve lift could significantly enhance the mixture and in-cylinder tumble motion because of the accelerated air flow. Also, it can be found that the fuel distribution is more affected by earlier injection (during intake process) than that of later injection (end of compression). These may contribute to an improvement in the air-fuel mixing but also to an optimization of intake and exhaust system.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.6
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• pp.629-637
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• 2015

As concern about energy security and global warming many countries have been making effort to reduce fossil fuel. In the case of US, as one of the efforts, the standards of the alcohol vehicle fuels(including blended with gasoline) have been established. Alcohol is known that make some trouble concerning startability, durability and corrosion when using as fuel of a conventional vehicle. For these reason, alcohol usage needs not only the fuel standard, but also a modified car. In the case of Korea, although there are no the standard and the modified vehicle yet, high concentration alcohol blended fuel has being sold at illegal market. In this study, exhaust gas and performance of the conventional vehicle that alcohol(methanol and isopropyl alcohol) blends were fueled were measured to notify danger of using them without preparation of institutional arrangements. Also, to analyze correlation characteristics of the fuels and them, property test of the fuels was conducted. The test result show that bad-startability caused by low RVP and high T10 affected increase in NMOG and CO. NOx was increased under the highest short term fuel trim caused by high Oxygen content and low NHV of alcohol. According to increasing as alcohol content, fuel economy and acceleration ability were decreased but $CO_2$ was not significantly decreased.