• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.3
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• pp.136-142
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• 2000

With the significant growth of the number of vehicles environmental problems is raised. NOx SOx, and PM emissions in diesel powered vehicles are larger than that in gasoline because the development of pollutants reduction techniques has not been yet achieved. So it is need to develop after-tratment or to convert into alternative fuel to satisfy emission regula-tion. Among the after-treatment systems to reduce the diesel emissions studies with diesel oxidation catalyst(DOC) are done greatly. In this study using DOC reduction efficiency with the change of temperature and catalyst loading was calculated through measurements of CO, HC, PM. and SOX.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.96-101
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• 2005

Cogeneration is an energy conversion process, where electricity and useful heat are produced simultaneously in one process. Also, carbon dioxide emissions can be reduced as well. The cogeneration process may be based on the use of steam, gas turbines or combustion engines. However, there have been few models with an output of less than 100 kilowatt. In the present study, a spark ignited gas engine with generation output of 10 kilowatts was developed for micro cogeneration package. The gas engine shows 29.2$\%$ of thermal efficiency under Stoichiometric combustion and 33.6$\%$ of thermal efficiency under lean combustion. NOx emission shows less than 10ppm at 13$\%$ oxygen under stoichiometric combustion and about 100ppm at 13$\%$ oxygen under lean combustion.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.171-178
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• 2014

From now on, in order to meet more stringer diesel emission standard, diesel vehicle should be equipped with emission after-treatment devices as NOx reduction catalyst and particulate filters. Urea-SCR is being developed as the most efficient method of reducing NOx emissions in the after-treatment devices of diesel engines, and recent studies have begun to mount the urea-SCR device for diesel passenger cars and light duty vehicles. That is because their operational characteristics are quite different from heavy duty vehicles, urea solution injection should be changed with other conditions. Therefore, the number and diameter of the nozzle, injection directions, mounting positions in front of the catalytic converter are important design factors. In this study, major design parameters concerning urea solution injection in front of SCR are optimized by using a CFD analysis and Taguchi method. The computational prediction of internal flow and spray characteristics in front of SCR was carried out by using STAR-CCM+7.06 code that used to evaluate $NH_3$ uniformity index($NH_3$ UI). The design parameters are optimized by using the $L_{16}$ orthogonal array and small-the-better characteristics of the Taguchi method. As a result, the optimal values are confirmed to be valid in 95% confidence and 5% significance level through analysis of variance(ANOVA). The compared maximize $NH_3$ UI and activation time($NH_3$ UI 0.82) are numerically confirmed that the optimal model provides better conversion efficiency of $NH_3$. In addition, we propose a method to minimize wall-wetting around the urea injector in order to prevent injector blocks caused by solid urea loading. Consequently, the thickness reduction of fluid film in front of mixer is numerically confirmed through the mounting mixer and correcting injection direction by using the trial and error method.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.73-81
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• 2006

A commercial diesel engine was converted into a dedicated natural gas engine to reduce the exhaust emissions in a retrofit of a diesel-fueled vehicle. The cylinder head and piston were remodeled into engine parts suited for a spark ignition engine using natural gas. The remodeling of the combustion chamber changed the compression ratio from 21.5 to 10.5. A multi-point port injection(MPI) system for a dedicated natural gas engine was also adopted to increase the engine power and torque through improved volumetric efficiency, to allow a rapid engine response to changes in throttle position, and to control the precise equivalence ratio during cold-start and engine warm-up. The performance and exhaust emissions of the retrofitted natural gas engine after remodeling a diesel engine are investigated. The emissions of the retrofitted natural gas engine were low enough to satisfy the limits for a transitional low emission vehicle(TLEV) in Korea. We concluded that a diesel engine can be effectively converted into a dedicated natural gas engine without any deterioration in engine performance or exhaust emissions.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.7-14
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• 2002

In order to reduce exhaust omissions of spark ignition engine, it is important not only to improve catalyst conversion efficiency but also to directly reduce engine out exhaust emissions, during cold starting and warm up process. Therefore many researchers have been attracted to develop an early fuel evaporator(EFE) by Introducing a ceramic heater fur a solution of engine out exhaust emissions in SI engine. But, the performance of the EFE in MPI engine to reduce the exhaust emissions and to improve the cold startability has not been clarified yet. The purpose of this study is to evaluate the feasibility of a glow plug far EFE. Impinging spray using heated and unheated glow plug helps the vaporization of the fuel and heat up the three way catalyst sufficiently. The amount of CO, and UHC is reduced overall. The amount of NOx is higher at the initial stage, but become lower as time goes on than without glow plug.

• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.540-550
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• 2013

Various efforts have been explored to save the cost in many industrial fields. In order to recover the residual thermal energy from the flue gas, an extreme high efficiency heat exchanger is planning to install at a power plant. The gas temperature will be reduced to $40^{\circ}C$ from $115^{\circ}C$. Thus gas buoyancy decreases, and dispersion of nitrogen oxides is expected to deteriorate as increasing relative humidity. In this study, the conversion of nitrogen monoxide to nitrogen dioxide and dispersion regime are investigated through computational modeling. Nitrogen dioxide which indicates 0.1 ppm at 85 m from the ground could be propagated to 620 m at $115^{\circ}C$ of the flue gas, whilst when cooled down to $40^{\circ}C$, it expands up to 750 m. The ground level influence area showed more expansion of dispersion, approximately to 930 m.

• New & Renewable Energy
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• v.7 no.2
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• pp.10-17
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• 2011

Korea is the 11th largest energy consumption country and 96% of its total energy consumption depends on imports from overseas. Therefore it is a very important task to secure renewable energy sources which can reduce both the carbon-dioxide emission and dependency on overseas energy imports. Among the various renewable energy sources, organic wastes are important sources. In Korea, 113 million toe of methane is generated from organic wastes annually, but only 3.7% is effectively used for energy conversion. Thus, it is very important to make better use of organic wastes, especially for power generation. The goals of this project are to develope the fuel supplying system of Bio Gasturbine (GT) for 5MW-class co-generation system. The fuel supplying system mainly consists of $H_2S$ removal system, Bio Gas compression system, Siloxane removal system and moisture separating systems. The fuel requirement of 5MW-class GT is at around 60% of $CH_4$, $H_2S$ (<30 ppm), Siloxane(<10 mg/$nm^3$) and supply pressure (> 25 bar) from biogas compressor. Main mechnical charateristics of Bio Gasturbine system have the specific performance; 1) high speed turbine speed (12,840 rpm) 2) very clean emmission NOx (<50 ppm) 3) high efficiency of energy conversion rate. This paper focuses on the development of design technology for food waste biogas pretreatment system for 5MW-class biogas turbine. The study also has the plan to replace the fuel of gas turbine and other distributed power systems. As the increase of bioenergy, this system help to contribute to spread more New & Renewable Energy and the establishment of Renewable Portfolio Standards (RPS) for Korea.

• New & Renewable Energy
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• v.6 no.1
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• pp.29-37
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• 2010

Biogas is a carbon neutral energy and consists of mostly methane and carbon dioxide, with smaller amounts of water vapor, and trace amounts of $H_2S$, Siloxane and other impurities. Hydrogen sulfide and Siloxane usually must be removed before the gas can be used for generation of electricity or heat. The goals of this project are to develope the Fuel conditioning system of Land Fill Gas for 30kW-Micro Gas Turbine co-generation system. The fuel conditioning system mainly consists of $H_2S$ removal system, Land Fill Gas compressor, Siloxane removal system and many filtering systems. The fuel requirement of 30kW MGT is at least 32% of $CH_4$, $H_2S$ (<30 ppm), Siloxane (<5ppb) and supply pressure (> 0.6 MPa) from LFG compressor. Main mechnical charateristics of Micro Gas Turbine system by using LFG have the specific performance; 1) high speed turbine speed (96,000 rpm) 2) very clean emmission NOx (<9 ppm) 3) high efficiency of energy conversion rate. This paper focuses on the development of design technology for LFG fuel conditioning system. The study also has the plan to replace the fuel of gas turbine and other distributed power systems. As the increase of Land Fill Gas (LFG), this system help to contribute to spread more New & Renewable Energy and the establishment of Renewable Portfolio Standards (RPS) for Korea.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.101-109
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• 2010

Efficient L-lactic acid production from Jerusalem artichoke tubers, by Lactobacillus casei G-02, using simultaneous saccharification and fermentation (SSF) in a fed-batch culture, is demonstrated. A kinetic analysis of the SSF revealed that the inulinase activity was subjected to product inhibition, whereas the fermentation activity of G-02 was subjected to substrate inhibition. It was also found that the intracellular NADH oxidase (NOX) activity was enhanced by the citrate metabolism, which dramatically increased the carbon flux of the Embden-Meyerhof-Parnas (EMP) pathway, along with the production of ATP. As a result, when the SSF was carried out at $40^{\circ}C$ after an initial hydrolysis of 1 h and included a sodium citrate supplement of 10 g/l, an L-lactic acid concentration of 141.5 g/l was obtained after 30 h, with a volumetric productivity of 4.7 g/l/h. The conversion efficiency and product yield were 93.6% of the theoretical lactic acid yield and 52.4 g lactic acid/l00 g Jerusalem artichoke flour, respectively. Such a high concentration of lactic acid with a high productivity from Jerusalem artichokes has not been reported previously, making G-02 a potential candidate for the economic production of L-lactic acid from Jerusalem artichokes on a commercial scale.

• Clean Technology
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• v.26 no.2
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• pp.145-150
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• 2020

Nitrous oxide (N₂O) is one of the six greenhouse gases, and it is essential to reduce N₂O by showing a global warming potential (GWP) equivalent to 310 times that of carbon dioxide (CO₂). Selective catalytic reduction (SCR) is a technology that converts ammonia into harmless N₂ and H₂O by using ammonia as a reducing agent to remove NOx, one of the air pollutants; the process also produces high denitrification efficiency. In this study, the Fe-BEA catalyst was steam-treated at 100 ℃ for 2 h before Fe ion exchange in the fixed bed reactor in order to investigate the effect of the steam-treated Fe-BEA catalyst on the NH₃-SCR reaction. NH₃-SCR reaction test of synthesized catalysts was performed at WHSV = 180 h^-1, 370 to 400 ℃ in the fixed bed reactor. The Fe-BEA(100) catalyst steam-treated at 100 ℃ showed a somewhat higher activity than the Fe-BEA catalyst at 370 to 390 ℃. The catalysts were characterized by BET, ICP, NH₃-TPD, H₂-TPR, and ²⁷Al MAS NMR in order to determine the cause affecting NH₃-SCR activity. The H₂-TPR result confirmed that the Fe-BEA(100) catalyst had a higher reduction of isolated Fe³⁺ than the Fe-BEA catalyst, and that the steam treatment increased the amount of isolated Fe³⁺ as an active species, thus increasing the activity.