• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.123-130
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• 2005

In this study, we evaluated the CH4 and CO conversion efficiencies over the oxidation catalysts for natural gas vehicle with lean-burn system. On the fresh catalyst, the conversion efficiency was increased when the loading of precious metal was increased. On the aged catalyst, the conversion efficiency was decreased as increasing the excess air ratio. We could confirm the measuring conversion efficiency of the unsteady state with the FTIR and that of steady state with the GC The temperature increasing ratio of unsteady state is acceptable from 3$^{\circ}C$/min. to 15$^{\circ}C$/min. for the evaluation of catalyst conversion performance , which has within the 4$\%$ of the difference of conversion efficiency. We observed a physical behavior of the thermal aged catalyst's surface using TEM and BET device. It was found that the precious metal was grown to the micro-scopic size by thermal aging process.

• New & Renewable Energy
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• v.4 no.4
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• pp.37-43
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• 2008

Three properties of food waste are water 80%, ash 3%, volatile matter 17%. When food waste goes through treatment process such as removal of foreign substances, removal of water as well as sodium, dryness, and pulverization, it transforms into 4,000 Kcal/kg purverized fuel if moisture content is below 13%. Fuel ratio (fixed carbon/volatile matter) of purverized fuel is low compared with bituminuous coal. Ignition temperature measured by thermogravimetry analyzer is about $460^{\circ}C$. Combustion test of purverized fuel have been performed using energy recovery facility which include storage tank of dewatered cake, dryer, hammer mill, combuster including burner, boiler, flue gas treatment equipment. When 160-180 kg/hr of fuel is steadily supplied to burner for 3 hours, combustor temperature reaches about $1000^{\circ}C$ and CO is 77-103 ppm at 1.55 excess air ratio and SOx and Cl are under 2 ppm and 1ppm, respectively. This experiment demonstrate that purverized fuel made from food waste could be an alternative clean energy at the age of high oil price.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.149-152
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• 2008

Three properties of food waste are water 80%, ash 3%, volatile matter 17%. When food waste goes through treatment process such as removal of foreign substances, removal of water as well as sodium, dryness, and pulverization, it transforms into 4,000Kcal/kg purverized fuel if moisture content is below 13%. Fuel ratio(fixed carbon/volatile matter) of purverized fuel is low compared with bituminuous coal. Ignition temperature measured by thermogravimetry analyzer is about $460^{\circ}C$. Combustion test of purverized fuel have been performed using energy recovery facility which include storage tank of dewatered cake, dryer, hammer mill, combuster including burner, boiler, flue gas treatment equipment. When 160-180 kg/hr of fuel is steadily supplied to burner for 3 hours, combueter temperature reaches about $1000^{\circ}C$ and CO is 77-103ppm at 1.55 excess air ratio and SOx and Cl are under 2ppm and 1ppm, respectively. This experiment demonstrate that purverized fuel made from food waste could be an alternative clean energy for high oil price era

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.4
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• pp.387-394
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• 2013

Hydrogen-compressed natural gas (HCNG) blend has attracted attention as a fuel that can reduce $CO_2$ emissions because it has low carbon content and burns efficiently. An increase in the compression ratio of HCNG engines was considered as one of the methods to improve their efficiency and reduce $CO_2$ emissions. However, a high combustion rate and flame temperature cause abnormal combustion such as pre-ignition or knocks, which in turn can cause damage to the engine components and decrease the engine power. In this study, the performance and knock characteristics with a change in the compression ratio of an HCNG engine were analyzed. The combustion characteristics of HCNG fuel were evaluated as a function of the excess air ratio using a conventional CNG engine. The effects of the compression ratio on the engine performance were evaluated through the same experimental procedures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.2579-2586
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• 2014

It is crucial to set up early the required performance of surface ship for preventing the risk factors such as an excess of performance, cost and period in development stage. In this study, MOP and MOE are proposed to establish the method for deriving alternatives, MOP represents the defensive effect for anti ship missiles and MOE is the ratio of cost and performance. The 16 engagement scenarios which selectively install RF decoy, RF jammer, CIWS and anti air missile are suggested. The simulation results by using NORAM tool operated by ROK Navy show that the ship survivability is 0.605~0.975 and MOP is 0.301~0.887. The analyzed results represent the operating scenario with RF decoy, RF jammer and short range anti air missile is the best cost and effectiveness measure.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.674-680
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• 2014

Monitoring systems of informations for ship performance have become important gradually for economical management of existing ship. Monitoring of NOx emission from marine diesel engines is one of them. The measurement of NOx emission, however has been many difficulties due to technical and costly problems. A monitoring by prediction method of NOx on-board ship according to sailing condition of ship could be an useful method. In this paper, it is discussed about modified method of one-zone model which has been utilized usually for analyzing the combustion process. The modified method is able to calculate the temperature of burned region from the result by one-zone model. Influences which excess air ratio during combustion process affected for the gas temperature and NOx emission were investigated. From the results variation of excess air ratio during combustion process could be estimated inversely through the comparison with measurement of NOx emission.

• Journal of Advanced Navigation Technology
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• v.14 no.1
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• pp.93-101
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• 2010

In this study, the performance characteristics of turbocharged engine is analyzed. The methods of engine performance improvements are suggested not only for full load characteristics of the engine but also for partial load characteristics of the engine, which is more frequently used in actual driving conditions. The compression ratio of the compressor is increased rapidly in a straight line pattern until 1260 engine rpm, and after that it is increased slowly to 2.5 ratio. Also the brake mean effective pressure increased until 1260 engine rpm and decreased rapidly after 1600 engine rpm. The higher the pressure ratio, the better the fuel consumption, air excess ratio and brake mean effective pressure. But those are higher in the rated revolution range than in the mid-low revolution range. The turbocharger is operated in a stable condition from 1260 rpm and its efficiency is low in the low speed range for the reason of its characteristics. The results of this study can be applied in the fundamental control methods of turbocharged engine for stable load and speed.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.630-638
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• 2009

A computational fluid dynamics(CFD) model is developed and validated with on-site experiments for a urea-based SNCR(selective non-catalytic reduction) process to reduce the nitrogen oxides($NO_x$) in a municipal incinerator. The three-dimensional turbulent reacting flow CFD model having a seven global reaction mechanism under the condition of low CO concentration and 12% excess air and droplet evaporation is used for fluid dynamics simulation of the SNCR process installed in the incinerator. In this SNCR process, urea solution and atomizing air were injected into the secondary combustor, using one front nozzle and two side nozzles. The exit temperature($980^{\circ}C$) of simulation has the same value as in situ experiment one. The $NO_x$ reduction efficiencies of 57% and 59% are obtained from the experiment and CFD simulation, respectively at NSR=1.8(normalized stoichiometric ratio) for the equal flow rate ratio from the three nozzles. It is observed in the CFD simulations with varying the flowrate ratio of the three nozzles that the injection of a two times larger front nozzle flowrate than the side nozzle flowrate produces 8% higher $NO_x$ reduction efficiency than the injection of the equal ratio flowrate in each nozzle.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.132.1-132.1
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• 2010

Anode off-gas of high temperature fuel cells such as MCFC still contain combustible components such as hydrogen, carbon monoxide and hydrocarbon. Thus, it's very important to fully burn anode off-gas and use the generated heat in order to increase system efficiency. In the present study, catalytic combustors have been applied to high temperature MCFC system so that the combustion of anode-off gas can be boosted up. Since the performance of catalytic combustor directly depends on the combustion catalyst, this study has been focused on the experimental investigation on the combustion characteristics of multiple commercial catalysts having different structures and compositions. In order to determine the design conditions of the catalytic combustor, parameters such as inlet temperature, space velocity and excess air ratio have been varied and optimized for combustor design. Results show that $H_2$ in off-gas assists $CH_4$ combustion in a way that it decreases minimum inlet temperature limit and increases maximum space velocity while keeping high fuel conversion efficiency.

• Journal of Energy Engineering
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• v.11 no.4
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• pp.350-358
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• 2002

The present work determined the flame structure characteristics of coal syngas combusted inside swirl burners with various nozzle types. Fuel nozzle types are largely classified into two groups of axial and tangential. Experiments were carried out for investigating the effects of fuel nozzle geometry, fuel composition ratio, heating rate, excess air, and degree of swirl on the turbulent diffusion flame structure. To determine the characteristics of the flame structure, axial type fuel nozzle diameter of laboratory-scale combustor is varied to 1.23, 1.96, and 2.95 ㎜ and the direction of tangential type nozzles are varied to radial, clockwise, and counter-clockwise. The comparison of the experimental results was performed to understand functional parameters relating the flame structure. Data analysis showed that the vertical straight flame height generally decreased with increasing swirl number and decreasing axial type nozzle diameter. Flame height established with tangential type nozzle is 3 times shorter than that with vertical type. The flame structures among the 3 different tangential fuel nozzles relatively showed no particular difference. By increasing the heating rate, the width of flame increased generally in both vertical and tangential flame. Within the present experimental parameters of the investigation, flame structure is mainly depends on the nozzle type of the combustor. The visually investigated flame lengths are confirmed through the analysis of temperature profile of each flame.