• Journal of the Korean Professional Engineers Association
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• v.32 no.5
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• pp.118-125
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• 1999

Air pollutant emissions from airplane engines are estimated about 2 to 4 % of mobile source of USA and European countries which is not a large portion of current air pollution. But the passengers and airfreights are continuously increasing 5 to 7% annually and potential demands of air transportation services come to present, it could effect air pollutant emissions of USA will increase within 15 years. In case of our country, there has been continuous increase of air transportation service due to considerable economic growth in recent years and increase of air pollutant emissions of major international airports has followed. Rapid increase of air transportation due to launching of Inchon International Airport could effect air pollution dominantly. By this circumstance environmental specialist as well as mass communication raised necessity of air pollutant emission regulation from airplane engines. It is estimated that air pollutant emissions from airplane engines in our country is 2.7% of automobile sources, 10,809 ton, which is the same level as USA and European countries. It is increased by 12,2% compared to air pollutant emissions during 1996 and it will be increased more than a half of current air pollutant emission within 15 years due to our country's economic condition. Therefore implementation of airplane engine emissions regulation as well as test standards and accumulation of technology about characteristics of airplane engine emission and reduction method are needed. And continuous estimation of air pollutant emission from airplane engines and monitoring of increment as well as development of countermeasures by long term are necessary.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.85-91
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• 2003

In this study, the potential possibility of oxygenated fuel such as Methyl tertiary butyl ether (MTBE) was investigated for the sake of exhausted smoke reduction from diesel engine. MTBE has been used as a fuel additive blended into unleaded gasoline to improve octane number, but the study of application for diesel engine was incomplete. Because MTBE includes oxygen content approximately 18%, it is a kind of oxygenated fuel that the smoke emission of MTBE is reduced remarkably compared with commercial diesel fuel. But, the NOx emission of MTBE blended fuel is increased compared with commercial diesel fuel. And, it was tried to analyze not only total hydrocarbon but individual hydrocarbon components from $C_1$ to $C_6$ in exhaust gas using gas chromatography to seek the reason for remarkable reduction of smoke emission. Individual hydrocarbons($C_1$~$C_6$) as well as total hydrocarbon of oxygenated fuel are reduced remarkably compared with diesel fuel. And, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission has been investigated, too. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel and cooled EGR method.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.2
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• pp.98-104
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• 2011

The introduction of a diesel engine into the passenger car and light duty applications in the United States involves significant technical challenges for the automotive makers. This paper describes the SCR System optimization procedure for such a diesel engine application to meet Tier2 Bin5 emission regulation. A urea SCR system, a representative $NO_x$ reduction after-treatment technique, is applied to a 3.0 liter diesel engine. To achieve the maximum $NO_x$ reduction performance, the exhaust system layout was optimized using series of the computational fluid dynamics and the urea distribution uniformity test. Furthermore a comprehensive simulation model for the key factors influencing $NO_x$ reduction performance was developed and embedded in the Simulink/Matlab environment. This model was then applied to the urea SCR system and played a key role to shorten the time needed for SCR control parameter calibration. The potential of a urea SCR system for reducing diesel $NO_x$ emission is shown for FTP75 and US06 emission standard test cycle.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.5
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• pp.401-410
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• 2002

Concerns for energy conservation, environmental pollution, and the fact that organic wastes account for a major portion of our waste materials, have created the interest of biogas, which usually contains about 60 to 70 percent methane, 30 to 40 percent carbon dioxide, and other gases, including ammonia, hydrogen sulfide, mercaptans and other noxious gases. Cyclone combustors are used for homing a wide range of fuels such as low calorific value gas, waste water, sludge. coal, etc. The 3-dimensional swirling flow, combustion and emission in a tangential inlet cyclone incinerator under different inlet conditions are simulated using a standard k-s turbulence model and ESCRS (Extended Simple Chemically-Reacting System) model. The commercial code Phoenics Ver.3.4 was used for the present work. The main parameters considered in this work are inlet velocity and air to fuel ratio. The results showed that the change of operating conditions had an influence on the shape and size of recirculation zones, mixture fraction and axial velocity which are important factors for combustion efficiency and emission behavior. The application of this kind of computer program seams to be promising as a potential tool for the optimum design of a cyclone combustor with low emission.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.169-170
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• 1996

In the past, it. was very difficult to distinguish thermal and non-thermal emission. Broadbent et a1. (1989) has developed a new technique with the help of the IRAS 60 micron emission. The distribution of non-thermal or synchrotron emission in the Galactic disk has been modeled from the 408 MHz all sky survey of Haslam et a1. (1982) after removal of the thermal component.. At. 408 MHz, t.here is very little absorption in the interstellar medium and the distribution along the line-of-sight. is inferred mainly from its presumed relationship to other tracers of spiral structure via a. number of fitted parameters. But. at lower frequencies, free-free absorption becomes important and can give some direct. information on the line of sight. distribution. We have modeled the thermal electron density according to the spiral arm models and the distribution of ionized hydrogen in the Galactic plane by Lockman (1976) and Cersosimo et. al. (1989) and have made predictions to compare with the surveys of Dwarakanath et al. (1990) at. 34.5 MHz and .Jones and Finlay (1974) at 29.9 MHz. The result confirms that the absorption model of the synchrotron emissivity in the Galactic plane is broadly corrected and illustrates the potential of the absorption technique.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.40.2-40.2
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• 2010

Polycyclic aromatic hydrocarbon (PAH) features have emerged as one of the most important infrared (IR) features since these PAH features dominate mid-IR spectra of galaxies and are ubiquitous within galactic and extragalactic objects. These PAH features have the potentials to become reliable star formation rate (SFR) proxies and diagnostics of physical conditions of interstellar medium, such as ionization states of dust grains and grain sizes. While constructing an unbiased library of 44 sample galaxies selected from 5MUSES sample, AKARI mJY Unbiased Survey of Extragalactic Sources in 5MUSES (AMUSES) intends to measure and to calibrate the PAH 3.3 mm emission feature which has not been studied extensively due to its weak strength and dearth of capable instruments. Out of 20 target galaxies, we detected the 3.3mm feature from eight galaxies and measured their line strengths, line widths and line ratios with other PAH emission features. Sample galaxies whose spectral energy distributions (SEDs) are classified as starburst-type have clearly stronger 3.3mm emission features than ones with AGN-type SEDs. We also found that there is a correlation between the PAH 3.3mm luminosity and total IR luminosity within our sample galaxies, albeit a large scatter. We further discuss implications of our results.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.309-312
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• 2002

Triode field emitters with planar-carbon-nanopaticle (CNP) cathodes were successfully fabricated using the conventional photolithography and the hotfilament chemical vapor deposition. Electron emission from a CNP triode emitter with a 12-${\mu}m$-diameter gate hole started at the gate voltage of 45 V, and the anode current reached the level of ${\sim}120$ nA at the gate voltage of 60 V, respectively. For the quantitative analysis of the Fowler-Nordheim (F-N) type emission from a CNP triode emitter, we carried out 2dimensional numerical calculation of electrostatic potential using the finite element method. As it turned out, a radial variation of electric field was very important to account for the emission from a planar emitting layer. By assuming the graphitic work function of 5 eV for CNPs, we were able to extract a consistent set of F-N parameters, together with the radial position of emitting sites.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.3-8
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• 1998

Using GIS and socio-economical data the relationship between human activities and global environmental change Is Analysed from the view point of food productivity and CO2 emission. Under the assumption that the population problem, the food problem and global warming due to energy consumption can be stabilized through managing land use, impacts of human activities such as consumption of food, energy and timber on global environment changes, and global population capacity are Analysed using developed system dynamics model in the research. In the model the world is divided into two groups: OECD countries and the others. Used global land use data set Is land cover map derived from satellite data, and potential distribution of arable land is estimated by the method of Clamor and Solomon which takes into consideration spatial distribution of climate data such as precipitation and evapotranspiration. In addition, impacts of CO2 emission from human activities on food production through global warming are included in the model as a feedback. The results of the analysis for BaU scenario and Toronto Conference scenario are similar to the results of existing models. From the result of this study, the human habitability in 2020 is 8 billion people, and CO2 emission in 2020 based on BaU Scenario and on Toronto Scenario is 1.7 and 1.2 times more than the 1986's respectively. Improving spatial resolution of the model by using global data to distribute the environmental variables and sauce-economical indices is left for further studies.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.2
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• pp.100-104
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• 1992

The research in this paper centers on a comparative risk assessment for nearby air pollution by carcinogenic metal emission from municipal solid waste incinerators. If a substance is identified as a potential human carcinogen, the carcinogenicity may be related to the chemical form of a substance and the route of exposure. This type of information with regard to carcinogenic uncertainty is incorporated into hazard quantification. In addition to the dioxin emission, the metal emission from municipal solid waste incineration is found to be a major contributor to human cancer risk via the inhalation route. The magnitude of risk by metals is about 5 times greater than that of risk by dioxins. Hexavalent form of chromium and cadmium compounds are major contributors to cancer risk from metal emission. In addition, hexavalent chromium is known to be human carcinogen while 2,3,7,8-TCDD is known to be only probable human carcinogen.

• Korean Journal of Environmental Agriculture
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• v.26 no.2
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• pp.131-140
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• 2007

Phospho-gypsum a primary waste by-product in phosphate fertilizer manufacturing industry and a potential source of electron acceptors, such as mainly of sulfate and a trace amount of iron and manganese oxides, was selected as soil amendment for reducing methane $(CH_4)$ emissions during rice cultivation. The selected amendment was added into potted soils at the rate of 0, 2, 10, and 20 Mg $ha^{-1}$ before rice transplanting. $CH_4$ flux from the potted soil with rice plant was measured along with soil Eh and floodwater pH during the rice cultivation period. $CH_4$ emission rates measured by closed chamber method decreased with increasing levels of phospho-gypsum application, but rice yield markedly increased up to 10 Mg $ha^{-1}$ of the amendment. At this amendment level, total $CH_4$ emissions were reduced by 24% along with 15% rice grain yield increment over the control. The decrease in total $CH_4$ emission may be attributed due to shifting of electron flow from methanogenesis to sulfate reduction under anaerobic soil conditions.