• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.21-26
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• 2011

Emissoin of heavy duty vehicle have much positioned in air pollution although its limited number of vehicles. CNG vehicles are coming to the fore as one of the solution of diesel vehicles. CNG vehicles exhaust smaller emission than diesel vehicles on PM and NOx. In this study, aftertreatment technologies are introduced on vehicles which use CNG and hydrogenmixed fuel. Withmixing hydrogen with CNG, combustion efficiency is enhanced, and harmful emission might be decreased, but methane that is main component of CNG brings green house effect. In order to remove methane and NOx in exhaust gas of CNG engine, methane oxidation catalyst and SCR technologies were respectively analyzed.

• Journal of the Korean Institute of Gas
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• v.14 no.4
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• pp.12-17
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• 2010

Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its high thermal efficiency and lower harmful emissions, including $CO_2$. However, the possibility of partial burn and misfire makes the benefits of natural gas fueled engine worse under lean burn operation condition, Hydrogen addition can promote the combustion characteristics while reduces emissions extremely. In this study, the effect of hydrogen addition on an engine performance was investigated. The results showed that thermal efficiency was increased due to the expansion of lean operation range under stable operation. NOx emission can be significantly reduced with the small increase in HC or CO emissions.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.1-10
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• 2023

Due to the development of the industrial revolution, regulations on exhaust emissions have been continuously strengthened to reduce the rapidly increasing greenhouse gas emissions. The use of environmentally friendly fuels is essential to meet these regulations. Hydrogen has been attracting attention as a future environmentally friendly fuel, but due to its material properties, it faces significant challenges in handling and storage. As an alternative, ammonia has been proposed. Ammonia can be easily liquefied at room temperature compared to hydrogen and has a high energy density. In order to examine the applicability of ammonia as an engine fuel, experiments were conducted to investigate the effects of changes in combustion control parameters in a direct injection ammonia combustion engine. The experiments were conducted by varying two variables: spark timing and excessive air ratio. Observations were made on combustion stability and the trends of exhaust emissions such as nitrogen oxides and unburned ammonia under the conditions of an engine speed of 1,500 rpm and medium to high loads (brake torque of 200 Nm). By optimizing the combustion control parameters, conditions for stable combustion even when using ammonia as the sole fuel were identified, and plans are underway to apply strategies for future expansion of the operating range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.696-701
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• 2018

The nitrogen oxides generated during combustion reactions have a great influence on the generation of acid rain and fine dust. As an NOx reduction method, exhaust gas recirculation combustion using Coanda nozzles capable of recirculating a large amount of exhaust gas with a small amount of air has recently been utilized. In this study, for the burner outlet with dual end opening, the use of a recirculation burner was investigated for the distribution of the pressure, streamline, temperature, combustion reaction rate and nitrogen oxides using computational fluid analysis. The gas mixed with the combustion air and the recirculated exhaust gas flow in the tangential direction of the circular cylinder burner, so that there is a region with low pressure in the vicinity of the fuel nozzle exit. As a result, a reverse flow is formed in the central portion of the burner near the center of the circular cylinder burner and the exhaust gas is discharged to the outside region of the circular cylinder burner. The combustion reaction occurs on the right side of the burner and the temperature and NOx distribution are relatively higher than those on the left side of the burner. It was found that the average NOx production decreased from an air flow ratio of 1.0 to 1.5. When the air flow ratio is 1.8, the NOx production increases abruptly. It is considered that the NOx production reaction increases exponentially with temperature when the air ratio is more than 1.5 and the NOx production reaction rate increases rapidly on the right-hand side of the burner.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.9-10
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• 2013

This study reports the results of an experimental investigation of emission and temperatures from the syngas-air premixed flame with a various mixture composition in the region of large equivalence ratios. The effects of hydrogen contents and equivalence ratios on the flame velocity, which reported before, and emission of syngas fuel are examined. In this study, representative syngas mixture compositions ($H_2:CO$) such as $H_2:CO=10:90$, 25:75, 50:50 and 75:25 and equivalence ratios from 0.5 to 5.0 have been conducted. The emissions of syngas fuel were measured by the high precision analyzer with enclosure configuration and the adiabatic temperatures are calculated by used Chemkin basis. The NOx emission level is coincided relatively well with the adiabatic temperature distributions in lean mixture conditions, but for rich mixture conditions NOx level was also increased again even though the adiabatic temperature decreases. Such an increasing characteristics in rich mixture conditions is coincided well with the tendency that rather the flue gas temperature increases.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.1
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• pp.91-98
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• 2008

Purpose: Radio-isotopes (RI) use has been steadily developing due to industrial and technical development in the modern medical society. Particularly, popularization of domestic cyclotrons dramatically enable hospitals to produce and use diagnostic radio-isotopes. Generally, only specific facilities such as hospitals, research institutes, nuclear power plants and universities can use radio-isotopes, they are also responsible for ventilation system. The strength of radioactivity in the air is strongly regulated and controlled by korea atomic energy law in Korea Institue of Nuclear Safety (KINS), so that air radioactivity exposure can lead to environmental pollution surrounding places. In this study, we'd like to find out the investigation and the present condition of the controlled ventilation system in domestic hospitals by an emission standard from KINS, and try to reach an agreement about how to use the ventilation system. Result: Definition of filters, features and structures of pre-filters, hepa-filters, charcol filters, filter exchange procedures and precautions are explained. RI deflation concentration and filter exchange cycle have been presented as a standard prescribed in the rules of KINS. The Radiation Control Management System (RCMS) introduced by Seoul National University Bundang Hospital linking to digital pressure gauge with computer controller in another medical facilities were described in details. Conclusions: The system of medical facilities using RI has been remarkably developing in 21 century. Especially, radiation safety control system has also been grown rapidly into the subdivision, specialization, advanced technology along with international technical improvement. However, As far as current RI ventilation system is concerned, it has nothing better than doing in the past. Preferentially, to reinforce this, more sophisticated system with strict periodic filter exchange and exhaust air control guidance should be introduced by applying brilliant domestic information technology for RCMS and digital gauge method. From personal point of view as a radiation safety manager, I have provide with present problems and improvements. Futhermore, more improved guidance should be conducted.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.379-387
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• 2011

Research and development of LP EGR system for the performance improvement and emission reduction on diesel engine is proceeding at a good pace. LP EGR system seems to be helpful method to further reduce$NO_x$ emissions while maintaining PM emissions at a low level because the boost pressure is unchanged while varying EGR rate. This study is experimentally conducted on a 2.0L common rail DI engine at the medium load condition (2000 rpm, BMEP 1.0 MPa, boost pressure 181.3 kPa) that difficult to use large amount of EGR gas because of deteriorations of performance and fuel consumption. And we investigated the characteristics of performance and fuel consumption while varying EGR systems. The overall results using LP EGR system equipped with ETC identified benefits on reduction of PM and improvement of fuel consumption and thermal efficiency while keep the $NO_x$ level compared to HP EGR and LP EGR with back pressure valve.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1051-1056
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• 2014

Nitrous oxide ($N_2O$) is naturally generated from biological activity, such as bacteria's material exchange. However, recent $N_2O$ concentration in the atmosphere has being increased by the human activities such as industrial growth. One of factors to increase $N_2O$ concentration in the atmosphere is a $N_2O$ emission caused by the combustion of marine fuel oils. The marine transportation presently handles over 99 percent of the international freight cargoes and the number of ship is continuously increasing with increment of cargoes. In this study, author conducted a series of the experimental investigations on which combustion of fuels containing different element concentrations used in a 4-stroke marine diesel engine affect $N_2O$ emissions in the exhaust gas. Moreover, it is assessed on the extent to which fuel combustion patterns in the combustion chamber affect $N_2O$ emissions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.3
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• pp.14-25
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• 2019

From 2019 onwards, more stringent regulations (from Stage 4 to Stage 5) are to be implemented in Europe in order to reduce the air pollutant emissions. In South Korea, the government authorities started to make new regulation to meet the European regulation. As a first step, the air pollutant emissions such as CO, NOx, SOx, TSP, $PM_{10}$, $PM_{2.5}$, VOC, $NH_3$ by agricultural machinery were analyzed based on CAPSS inventory along with the analysis in the general aspect in this study. Three levels of analysis was conducted each in agricultural machinery aspect along with in the general aspect. Per agricultural tractor, all kinds of the air pollutant emissions decreased by 25, 25, 99, 25, 25, 25, 25% for the CO, NOx, SOx, TSP, $PM_{10}$, VOC, $NH_3$ emissions each from the year 2000 to the year 2014. Per combine harvester, all kinds of the air pollutant emissions decreased by 63, 63, 91, 63, 63, 63, 63% for the CO, NOx, SOx, TSP, $PM_{10}$, VOC, $NH_3$ emissions each from the year 2000 to the year 2014.

• Journal of the Korean Institute of Gas
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• v.26 no.5
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• pp.28-34
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• 2022

Since semiconductor factories are located in densely populated areas, safe handling of hazardous materials handled in the manufacturing process is of utmost importance. In particular, the types of hazardous substances discharged after handling in the semiconductor manufacturing process are very diverse, and the treatment methods such as combustion, absorption and adsorption methods for each material are very complicated. Therefore, in recent semiconductor exhaust treatment processes, two or more treatment methods are applied to one treatment facility, and unexpected accidents occur due to the application of such a complex treatment method. In this study, the cause of accidents in treatment facilities that applied both the scrubber method and the electrostatic precipitation method, which are recent accident cases, are identified, and preventive measures are suggested to find out the points to be noted when applying the complex treatment method.