• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.338-343
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• 2019

The water transport and water content of the electrolyte membrane greatly affect the performance of the membrane in PEMFC(Proton Exchange Membrane Fuel Cell). In this study, the parameters (electroosmotic coefficient, water diffusion coefficient) of polymer membranes for water transport were measured by a simple method, and water flux and ion conductivity were simulated by using a model equation. One dimensional steady state model equation was constructed by using only the electro-osmosis and diffusion as the driving force of water transport. The governing equations were simulated with MATLAB. The electro-osmotic coefficient of $144{\mu}m$ thick polymer membranes was measured in hydrogen pumping cell, the value was 1.11. The water diffusion coefficient was expressed as a function of relative humidity and the activation energy for water diffusion was $2,889kJ/mol{\cdot}K$. The water flux and ion conductivity results simulated by applying these coefficients showed good agreement with the experimental data.

• Journal of Auto-vehicle Safety Association
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• v.14 no.4
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• pp.43-52
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• 2022

Recently, the government has been expanding the supply of hydrogen vehicles according to the roadmap for vitalizing the hydrogen economy, but is developing safety assessment and inspection technology for the relevant vehicles. This study analyzed the prevention of hydrogen bus accidents' economic effect that arises from the application and development of large-capacity CHSS oil pressure repetition-test assessment technology, hydrogen bus internal chamber pressure transmission and emission volume inspection technology, among various technologies capable of assessing the safety of a hydrogen bus fuel system. To this end, the contingent valuation method (CVM), one of the value evaluation methods of non-market goods, was applied to investigate users' willingness to pay for each inspection technology. The survey for users' willingness to pay was conducted by attaching posters to promote surveys on the internet and within buses to the entire public. As a result of the analysis, the average WTP of the hydrogen bus internal chamber pressure transmission volume inspection technology was 25.3 KRW, the average WTP of the hydrogen bus internal chamber pressure emission volume inspection technology was 18.6 KRW, and the average WTP of the large-capacity CHSS oil pressure repetition-test assessment technology was measured at 16.7 KRW. In addition, the costs and benefits of the introduction of the relevant inspection technology were defined through the interviewing of experts at related research institutions and businesses. As a result of conducting an economic analysis (4.5% discount rate) according to the development of each inspection technology, economic feasibility was seen in all assessment and inspection technologies. As much as the technology is indispensable for the safe use of hydrogen buses, it shows that investment in related technology is very necessary in the future. However, because it was decided that the relevant analysis will differ according to the distribution rate of hydrogen buses, further analysis following this future distribution rate of hydrogen buses is needed, and future users should be made clearly aware of the safety and environmental nature of the technology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.608-613
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• 2019

NOx (Nitrogen oxide) in the exhaust gas from vehicle engines is considered one of the most harmful substances in air pollution problems. NOx is made when combustion occurs under high temperature conditions and EGR (exhaust gas recirculation) is normally used to lower the combustion temperature. As the EGR ratio increases, the NOx level becomes low, but a high EGR ratio makes the combustion unstable and causes further air pollution problems, such as CO and unburned hydrocarbon level increase. This study showed that fuel droplets could move more freely by the radiation of sonic wave for the stable combustion. In addition, the engine performance improved with increasing EGR ratio. As a basic study, the effect of sonic wave radiation on the velocity of fuel droplets was studied using CFD software. The results showed that the velocity of small droplets increased more under high frequency sonic wave conditions and the velocity of the large droplets increased at low frequency sonic wave conditions. In addition, an engine analysis model was used to study the effects of the increased combustion stability. These results showed that a 15% increase in EGR ratio in combustion resulted in a 45% decrease in NOx and a 10% increase in thermal efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.10
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• pp.837-844
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• 2014

Automotive manufacturers have recently developed various technologies for improving fuel economy and satisfying enhanced emission regulations. The ultra-lean direct injection engine is a promising technology because it has the advantage of improving thermal efficiency through the deliberate control of ignition. A conventional LPG engine has been redesigned to an ultra-lean-burn LPG direct injection engine in order to adopt combustion system of ultra-lean-burn. This study is aimed at investigating the effect of a change in the compression ratio on the performance and emission characteristics of a lean-burn LPG engine. The fuel consumption, heat release rate, combustion pressure, and emission characteristics are estimated depending on changing the effect of compression ratio. When the compression ratio is increased, it is difficult to improve the fuel consumption owing to an unstable combustion state, but the total hydrocarbon and nitrogen oxide emissions are reduced.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1972.03a
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• pp.5-6
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• 1972

Noise and air pollution, which accompany the development of industry and the increase of population, contribute to the deterioration of urban environment. The air pollution level of Seoul has gradually increased and the city residents are suffering from a high pollution of noise. If no measures were taken against pollution, the amount of emission of pollutant into air would be 36.7 thousand tons per year per square kilometer in 1975, three times more than that of 1970, and it would be the same level as that of United States in 1968. The main sources of air pollution in Seoul are the exhaust has from vehicles and the combustion of bunker-C oil for heating purpose. Thus, it is urgent that an exhaust gas cleaner should be instaled to every car and the fuel substituted by less sulfur-contained-oil to prevent the pollution. Transportation noise (vehicular noise and train noise) is the main component of urban noise problem. The average noise level in downtown area is about 75㏈ with maximum of 85㏈ and the vehicular homing was checked 100㏈ up and down. Therefore, the reduction of the number of bus-stop the strict regulation of homing in downtown area and a better maintenance of car should be an effective measures against noise pollution in urban areas. Within the distance of 200 metres from railroad, the train noise exceeds the limit specified by the pollution control law in Korea. Especially, the level of noise and steam-whistle of train as measured by the ISO evaluation can adversely affect the community activities of residents. To prevent environmental destruction, many developed countries have taken more positive action against worsening pollution and such an action is now urgently required in this country.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.200-202
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• 2009

본 논문에서는 수소연료전지자동차의 고전압 시스템에서 직 간접접촉에 의한 인체 감전사고를 방지하기 위한 전기안전 평가기법인 절연저항과 전기적연속성 등에 대하여 분석하였다. ISO, UNECE, Japan Attachment 등의 외국 규격에서는 감전보호를 위한 평가 기준을 제시하고 있지만 세부적인 평가방법에 대해서는 명확하게 규정하고 있지 않기 때문에 전기안전 평가를 위한 측정방법 및 측정장비에 대한 최소한의 기준 정립이 필요한 실정이다. 따라서 본 연구에서는 전기안전 평가기법에 대한 HFCV 실차 상태의 실험을 통하여 나타난 문제점 분석을 통하여 감전보호를 위한 전기안전 평가기법 중 전기적 연속성 및 절연저항에 대한 측정방법과 측정장비의 사양에 대하여 제시하고자 한다.

• Proceedings of the Korean Society for Quality Management Conference
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• 2010.04a
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• pp.465-470
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• 2010

Korea government declared that "low carbon, green growth" through green technologies and clean energy to be the new national vision for the next 60 years(President's Liberation Day speech on Aug. 15, 2008). And succeeding "Green New Deal" plan involves nine core projects including energy saving, recycling, clean energy development. It is because hydrogen fuel cell vehicles, using electricity from chemical reaction of hydrogen and oxygen, let out water which is a by-product of such chemical reaction instead of emitting harmful particulate and gases such as NOX, SOX and CO2 that hydrogen fuel cell vehicles and its technology are drawing public attention as one of the sensible solutions in accomplishing "low carbon, green growth" agenda. Nevertheless There are many chances that let the people have a practical experience of hydrogen fuel cell vehicles. Sometimes new products, including hydrogen fuel cell vehicles, made by advanced technology can not penetrate through the market when it faces public skepticism that is stimulated from lack of knowledge and experience. That is the reason why not only cost benefit analyses and scientific risk assessments but also public acceptance studies toward hydrogen fuel cell vehicles have to be performed [Schulte, 2004]. This research address a need for comprehensive study on factors influencing public acceptance of hydrogen fuel cell car, specifically focusing on impacts of personal experience related to governmental science and technology policy toward public acceptance.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.3
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• pp.189-197
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• 2016

Green vehicles include electric vehicles, natural gas vehicles, and fuel cell vehicles (FCVs). In FCVs, pressure vessels have cylinder valves to control hydrogen flow. These valves should be of high quality in terms of safety because hydrogen is stored at ultra-high pressure in pressure vessels. Hence, safety evaluation of these valves is necessary to secure the safety of the FCV. A structural analysis of the cylinder valve was conducted in this study by using a commercial finite element analysis code. The results showed that the safety factor of valve component ranged 1.06-186.44. After categorizing, the stress components at critical points of the cylinder valve parts were evaluated using the corresponding allowable design criteria in the ASME code. The pressurization cycle test was performed as per the regulation to evaluate the safety of the valve.

• Journal of Hydrogen and New Energy
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• v.23 no.6
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• pp.634-639
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• 2012

The contribution levels of emissions from the heavy-duty vehicles have been continuously increased. Among the exhaust emissions, NOx (nitric oxides) have a ratio of 73.2% and particle matters have a proportion of 61.8% in the heavy-duty vehicles. Also, natural gas vehicles have the 78.9% of total registered local buses in Korea. Therefore, the investigation on emission characteristics of heavy-duty vehicles using CNG and diesel fuel according to the various driving cycles was carried out in this study. In order to analyze the emission characteristics, the five kinds of buses by using CNG and diesel fuels with a after-treatment devices (DPF, p-DPF) was used and five test driving schedules were applied for analysis of emission characteristics in a chassis dynamometer. To analyze the exhaust emission, the exhaust emission and PM analyzers were used. From this study, it is revealed that diesel buses with after-treatment had reduced emission of CO, HC, PM but NOx. Also, NMHC emission of CNG bus have a higher level and NOx level was similar with diesel buses. In addition, emissions in NIER06 with slow average speed shows lowest levels compared to other test modes.

• Journal of IKEEE
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• v.21 no.2
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• pp.123-129
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• 2017

Proton Exchange Membrane Fuel Cell (FEMFC) is a strong candidate for future automobile and power generation because of its high power density, low emission and low operation temperature. The major concerns of the gas diffusion layer (GDL) inside a FEMFC is water management. The GDL is typically comprised of carbon for electrical conductivity and PTFE for Hydrophobicity. In this simulation, GDL flooding was investigated using a simplified approach method of an established equation models(Fick' Law, Darcy, Law, Stefan-Maxwell diffusion). The performance of GDL was shown using result of the inner heat, water density and oxygen density of the cell using model equations. The catalyst layer mode in FEMFC showed results of effectiveness factor, Butler-volmer and hydrogen flux density. These results are interesting because the influence of several factors has been shown and the information will be helpful for fuel cell design.